Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHODS USABLE IN CONNECTION WITH DISPENSING
FLE~ISLE SHEET MATERIAL FROM A ROLL
FIELD OF THE INVENTIONS
[O1] The present inventions relate to the dispensing of flexible sheet
material from a roll.
In particular, the present inventions relate to various features that may be
advantageously used by themselves or in conjunction with each other, in
connection
with the dispensing of web products (e.g., paper towels or napl~ins) from a
roll in an
institutional setting. A proximity sensing circuit and method in accordance
with one
invention may be advantageously applied in virtually any application where it
is
desired to detect the presence or proximity of a user or object relative to
something
else. The inventions described herein compliment each other as well as: the
powered
dispensing and user sensing related inventions disclosed in co-pending
commonly
owned patent application Serial No. 09/081,637, filed May 20, 1998; and the
powered
feed transfer related inventions described in co-pending commonly owned
application
Serial No. 09/604,811, filed June 28, 2000.
BACKGROUND OF THE INVENTIONS
[02] Dispensers for toweling have primarily fallen into one of three
categories: those that
dispense segments of a continuous (endless) towel, those that dispense
individual
folded paper towels, and those that dispense towel segments separated from a
roll of
paper sheet material. Continuous towels are generally made of a reusable
material
and form a towel loop outside of the dispenser cabinet that may be grasped for
use.
Folded paper towels are generally pre-cut and folded into various
configurations to be
individually dispensed for use. Rolls of paper toweling are generally wound
around a
central core. Upon dispensing, segments of the sheet material are delivered
from the
dispenser and separated from the roll by tearing or cutting performed by the
dispenser
and/or the user.
[03] Continuous web dispensers, such as those disclosed in U.S. Pat. No.
2,930,663 to
Weirs and U.S. Pat. No. 3,858,951 to Rasmussen, require the user to pull on
the loop
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of exposed toweling in order to cause a length of clean toweling to be
dispensed and
the exposed soiled toweling to be correspondingly taken up within the
dispenser.
Although economical, the continuous exposure of the soiled toweling is deemed
unsightly and, therefore, unacceptable to many consumers when compared to the
many available alternatives. Further, the exposure and possible reuse of
soiled
toweling may present additional health hazards and sanitation concerns which
should
be avoided.
[04] The use of interfolded paper towels or C-fold paper towels eliminates the
potential
health risks associated with continuous web toweling. For instance, dispensers
for
folded paper towels, such as disclosed in U.S. Pat. No. 3,269,592 to Slye et
al., allow
a user to dispense the towels by pulling on the exposed end of each new
individual
towel. These dispensers are also easy to refill with folded towels. However, a
number
of the folded towels will sometimes drop out of the lower opening of the
dispenser
when only the exposed towel is pulled, especially when the stack of towels in
the
dispenser is small. This can result in a significant waste of paper towels.
Accordingly,
folded towels are not as economical as other kinds of alternative dispensers.
[OS] Roll towels are cheaper to manufacture and produce less waste than folded
towels.
Roll towels also eliminate the potential health and sanitation problems
associated with
continuous web toweling systems. Dispensers for roll towels may include a
lever,
crank, or other user-activated mechanism for dispensing a length of towel, and
a blade
for severing the length of towel from the remaining roll. However, as can be
appreciated, manual contact with a dispensing lever or the like raises health
concerns
for the user. To alleviate these health concerns, dispensers, such as U.S.
Pat. No.
4,712,461 to Rasmussen, eliminate contact with any part of the dispenser, and
instead
rely upon the user directly pulling the paper towel out of the dispenser. As a
result, the
paper towel must be provided with sufficient strength to effect rotation of
the feed
roller and actuation of the blade without premature tearing. Paper possessing
the
requisite strength to operate the dispenser is limited in the amount of
softness and
absorbency which can be provided to the paper towels.
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[06] Dispensers for roll towels have also been electrically powered. As shown
in U.S. Pat.
No. 5,452,832 to Niada, a light sensitive device is used to detect the
presence of a
user's hand in front of the dispenser and advance the toweling for a
predetermined
length of time. The dispensed length of paper towel is then separated from the
continuous web by pulling the paper against a serrated cutting member. While
the
feed roller is powered, the cutting action still requires the paper to possess
a certain
minimum strength and generally produces a rough, unsightly cut.
[07] U.S. Pat. No. 4,738,176 to Cassia discloses an electrically powered
dispenser which
also includes a reciprocating cutter to produce an individual towel from the
continuous web of paper. While this arrangement enables the use of softer and
more
absorbent paper, the dispenser requires a substantial amount of energy to
drive the
feed mechanism and the reciprocating cutter. Accordingly, the batteries must
be
replaced relatively frequently. Moreover, the system is more complex and
costly with
its use of one-way clutches.
[08] Also, in some electrically powered dispensers, such as U.S. Pat. No.
4,796,825 to
Hawkins, the paper will continually dispense while a hand or other object is
placed in
front of the sensor. Hence, the dispenser is subject to easy abuse and waste
of paper.
Moreover, some dispensers are subject to dispensing paper by the general
proximity
of a person irrespective of whether a paper towel is needed. In an effort to
avoid
abuses, some dispensers, such as U.S. Pat. No. 4,666,099 to Hoffinan, have
incorporated a waiting period where the dispenser will not operate for a brief
time
after each use. However, the need to wait can be frustrating to users under
some
circumstances.
[09] Previously mentioned copending application Serial No. 09/081,637
discloses an
electric motor powered dispenser which overcomes many of the disadvantages of
the
prior art described above. For example, in one aspect, the dispenser
facilitates the
dispensing of a roll of paper with spaced apart transverse lines of tearing
(e.g.
perforation lines) for easily separating individual sheets from the continuous
roll
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without cutting. As a result, paper with a high degree of softness and
absorbency can
be used without the high energy demands required by a reciprocating cutter. W
another aspect, the dispenser senses the leading edge of the continuous web of
paper
material to initiate a control device which controls the length of each
segment of
paper. In this way, the dispenser can always place the transverse tearing line
at the
proper position in relation to the discharge opening for each dispensed sheet,
irrespective of variations of the spacing for the tearing lines within a
tolerance range.
In another aspect, the dispenser includes a sensor for sensing the presence of
a sheet
that has been dispensed, but not removed, in order to prevent the dispenser
from
dispensing any more sheets until the previous sheet has been torn off. In this
way,
abuse of the dispenser and waste of the paper material can be minimized
without
requiring the use of a waiting period wherein the dispenser will not operate.
Accordingly, the dispenser is always ready for use.
[10] Other systems have been developed for sensing the proximity of, for
example, a hand
to a dispenser for controlling dispensing of an item, such as paper towels,
water, hand
soap, etc. For example, U.S. Pat. No. 5,694,653 to Harald discloses a system
that
senses the proximity of a person's hands to a water faucet, thereby providing
hands-
free operation of the faucet. According to Harald, the spout of a water faucet
is
coupled to an oscillator and functions like a transmitting antenna by emitting
a time-
varying primary electrostatic field. When a person's hands are placed in the
primary
electrostatic field in proximity of the spout, the person's body begins to
radiate a
secondary field in syncopation with the primary field. A receiver antenna
located
away from the spout, such as behind the front panel of a vanity, receives the
secondary field, which is processed for turning on the water. Several
different
receiver antennas can be used for detecting the relative position of a hand
with respect
to a particular receiver antenna for controlling, e.g., the temperature of the
water. To
provide sufficient sensitivity so that proximity of a hand with respect to the
Harald
sensor system open ates reliably, the signal driving the faucet spout must be
shielded
from the receiving antennas. Additionally, the receiving antennas must be
oriented
and shielded to avoid detecting the primary field.
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[11] U.S. Pat. No. 6,279,777 Bl to Goodin et al. discloses another hands-free
proximity
sensing system for a dispenser. According to Goodin et al., a proximity
sensing
system includes a theremin sensor and a second sensor, such as a conventional
infrared, ultrasonic, heat, light, proximity or audio sensor detector, for
detecting the
presence of a human body part in proximity to the dispenser. The theremin
sensor
includes two closely-spaced antenna panels that establish a capacitance
therebetween
independent of a ground connection. The antenna panels are coupled to an
oscillator
circuit that oscillates at a frequency related to the capacitance established
between the
two panels. When a person's hand comes into close proximity of the panels, the
capacitance provided by the persons' hands increases the capacitance between
the two
antenna panels, and thereby changes the frequency of oscillation and a first
output
signal is generated. The second sensor independently senses the presence of
the
person's hand and also generates a second output signal. The dispenser, in
response
to the first and second output signals, performs a dispensing operation. While
the
Goodin et al. sensing system purports to provide high reliability in avoiding
false
sensing situations, it is apparent that the stray capacitance provided by the
environment in which a Goodin et al. sensor is installed may adversely affect
the
frequency of oscillation of the oscillator such that the oscillator circuit
must be
calibrated so that the sensitivity of the theremin sensor can reliably sense
the change
in capacitance provided by a person's hand.
[12] As described above, roll towel dispensers may utilize a manual drive
mechanism such
as a user operated crank or lever to drive a feed mechanism to dispense the
towels, or
alternatively a powered drive mechanism. In either case, the feed mechanism
typically will include a drive roller and a pressure roller, also known as a
pinch roller,
which form a nip. When the rolled paper runs out in a conventional roll
dispenser, an
attendant must replace the roll and manually insert the leading edge of the
new roll
into the nip. This can require complex towel threading and loading sequences.
After
the attendant has placed the leading edge of the roll into the nip, the feed
mechanism
is operated in order to advance the leading edge through the feed mechanism,
thereby
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causing a length of paper towel to be unwound from the roll core and delivered
to the
user.
[13] In contrast to folded paper towel dispensers, conventional roll towel
dispensers do not
provide an economical way to replenish the towel supply when a partially
depleted
roll, i.e., a "stub" roll, remains within the dispenser. In some prior art
dispensers, a
new roll must be substituted for the stub roll, thereby resulting in the waste
of
whatever paper remains on the stub roll. This can result in increased
operational costs
as a significant amount of paper may be wasted in facilities with many
dispensers. To
overcome the problem of stub roll waste, other roll dispensers have been
designed to
dispense two rolls of web material sequentially such that upon depletion of a
primary
roll, feeding from a reserve roll is commenced.
[14] Prior art systems have accomplished this transfer by either modifying the
end of the
web material or modifying the roll core upon which the web material is wound,
such
as the system disclosed in U.S. Pat. No. 3,288,387 to Craven, Jr.
Alternatively, the
systems of U.S. Patent No. 3,628,743 to Bastian et al. and U.S. Patent No.
5,294,192
to ~mdoll et aI. sense the diameter of the primary roll in order to activate
the transfer
to the reserve roll, and the system of U.S. Pat. No. 3,917,191 to Graham, Jr.
et al.
senses the tension in the primary roll in order to detect when it is nearly
exhausted.
Unfortunately, tension responsive transfers are not particularly reliable
since
conditions other than reaching the end of the roll can trigger their
operation, such as
the slackening of the web or a break in the web material. Diameter responsive
transfers also have a drawback in that the reserve web begins dispensing prior
to the
complete exhaustion of the primary roll. Thus, for a short time web material
is
dispensed simultaneously from both rolls and again results in a waste of
material.
[15] In efforts to overcome these disadvantages, the systems of U.S. Patent
No. 4,165,138
to Hedge et al., U.S. Patent No. 4,611,768 to Voss, et al., and U.S. Patent
No.
4,378,912 to Perrin et al. provide transfer mechanisms that sense the absence
or
presence of paper from around a feed roll. In one system, this is accomplished
by a
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sensing finger which rides along the top surface of the web material and then
drops
down into a groove in the feed roll which is exposed when the trailing end of
the
primary web has been unwound from the roll. In response to the sensing finger
moving into the groove, the reserve web is introduced into the feed nip
between the
drive roller and the pressure roller, and the dispenser begins to feed the
reserve roll to
the user. This type of transfer mechanism generally eliminates the false
transfers
associated with tension responsive systems and reduces the amount of double
sheet
dispensing which occurs in diameter sensing transfer systems. The use of
sensing
fingers on the web material, however, produces extra friction which can
inadvertently
tear the web. Moreover, the introduction of additional components to sense the
absence of the web and transfer the reserve web to between the feed rollers
creates
opportunities for a transfer failure to occur.
[16] A need has therefore existed for a flexible sheet dispenser having an
automatic
transfer mechanism which, in addition to substantially eliminating
simultaneous
dispensing from both primary and reserve rolls, requires few additional parts
within
the dispenser and which is not prone to interference with the proper
dispensing of
either the working or reserve roll web material. A transfer mechanism that, to
a large
extent, fulfills this need is described in commonly assigned U.S. Patent No.
5,526,973
to Boone et al. Therein, movement and interengagement of one grooved feed
roller
relative to the other upon depletion of a stub roll, actuates a transfer
mechanism that
introduces a reserve web into the feed nip. While generally quite effective,
the
movement and spring biasing of a relatively high mass feed roller can lead to
difficulties. The feed roller spring bias force must be within a relatively
narrow
window. If the spring bias is set too high, the biasing force may inhibit
smooth
feeding of the web material through the rollers, and result in tearing of the
web
material. If it is set too low, the mechanism may not actuate effectively to
cause a
hansfer of feed to the reserve roll immediately upon depletion of the stub
roll. Over
time, the spring bias provided to move one roll relative to the other is prone
to
eventually decrease, e.g., due to fatigue of the spring, such that ultimately
the spring
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force may fall below the required relatively narrow range and thus be
insufficient to
properly actuate a web transfer.
[17] Previously mentioned co-pending application Serial No. 09/604,11
discloses a
dispenser having an electric motor powered transfer mechanism that overcomes
many
of the disadvantages of the prior art described above. That dispenser can
provide
hands flee, automatic feeding of a first sheet of a primary web roll, such as
a paper
towel roll, into a feed mechanism when its cover is closed. The dispenser can
also
automatically transfer its web feed supply from a working roll to a reserve
roll upon
the exhaustion of the working roll. The design eliminates the need for an
attendant to
thread the leading edge of a roll into the feed mechanism of the dispenser. It
also
reduces wasted paper because it does not begin to feed from a reserve roll
until the
working roll has been fully depleted. The dispenser includes a chassis having
a web
discharge opening and a feed mechanism for advancing the web to the web
discharge
opening. The dispenser also includes a sensor for determining when a portion
of the
web is absent from a side of the feed mechanism proximate the web discharge
opening. When such an absence is sensed, an automatic, powered web transfer
mechanism contacts the web located in front of the feed mechanism and
positions it in
the feed nip, i.e., between the rollers of the feed mechanism. The transfer
mechanism
includes a web transfer member and a motor for driving the transfer member in
the
direction of the feed mechanism. The dispenser also includes a retraction
mechanism
for returning the transfer bar to a rest position after the web has been
introduced into
the feed mechanism.
SUMMARY OF THE INVENTIONS
(18] The present inventions arose out of efforts to develop a "next
generation" sheet
material dispenser providing increased convenience and simplicity of use and
maintenance. In particular, it was an object of the inventors to provide a
dispenser
capable of carrying out dispensing operations in a reliable and controlled
manner that
would avoid the need for a user to make physical contact with the dispenser.
The
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inventors also sought to develop a dispenser that would, by virtue of its
various
features, minimize dispenser downtime due to depletion of the dispensed roll
material
or the dispenser power supply, or due to jams of the feed mechanism. Moreover,
the
inventors sought to develop a dispenser that would improve the efficiency of
institutional/building maintenance operations, by facilitating dispenser
maintenance
by unskilled personnel.
[19] It is an object of one of the present inventions to provide a proximity
sensing system
that senses the proximity of a person's hand or other body part, based on the
capacitance provided by the body part, and that automatically compensates for
environmental changes by adjusting the sensitivity of the sensor so that
changes in
capacitance provided by a person's hand (or other body part) are reliably
sensed,
regardless of the variations in stray capacitance provided by the environment
in which
the proximity sensor is placed.
[20] One or more of the above, and/or other objects, are achieved by the
various inventions
disclosed and claimed herein.
[2I] According to a first one of the inventions, a dispenser is provided for
dispensing
flexible sheet material. The dispenser includes a support for rotatably
supporting a
roll of sheet material. A feed mechanism is provided for advancing the sheet
material
out of the dispenser. A drive member is provided for driving the feed
mechanism.
The drive member is movably mounted for movement into and out of engagement
with the feed mechanism. A hold mechanism is provided for holding the drive
member in engagement with the feed mechanism. The hold mechanism is manually
releasable to pennit the drive member to be moved out of engagement with the
feed
mechanism.
[22] According to a second one of the inventions, a drive mechanism assembly
is provided
for selectively engaging with and driving a feed mechanism of a flexible sheet
material dispenser. The drive mechanism assembly includes a motor having a
drive
shaft, and a drive member attached to the drive shaft for drivingly engaging
the feed
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mechanism in an engagement position. A carrier retains therein the motor and
the
drive member. The carrier includes a rotatable mounting member for rotatably
mounting the motor and drive member to a dispenser chassis fox rotation as a
unit into
and out of the engagement position.
[23] According to a third one of the inventions, a method of removing a jam
from a
dispenser for dispensing flexible sheet material is provided. A sheet material
jam is
detected. A drive mechanism of the dispenser is disengaged from a feed
mechanism
of the dispenser. The jam is cleared from the path of the feed mechanism by
rotating
the feed mechanism while it is disengaged from the drive mechanism. The drive
mechanism is then reengaged with the feed mechanism.
[24] According to a fourth one of the inventions, a dispenser for dispensing
flexible sheet
material includes a feed mechanism, a drive mechanism for selectively driving
the
feed mechanism, and a control device for controlling the drive rmechanism. A
battery
container is provided for removably holding at least one battery for powering
at least
one of the drive mechanism and the control device. A power line input port is
provided, to which a power line may be connected to supply power to at least
one of
the drive mechanism and the control device in lieu of battery power. The power
line
input port is arranged in relation to the battery container such that (1) when
the battery
container is loaded with the at least one battery to supply power to at least
one of the
drive mechanism and the control device, the line input port is prevented from
being
connected to the power line; and (2) when the battery container is unloaded,
the
power line input port is readily accessible for connection of the power line.
[25] According to a fifth one of the inventions, a dispenser for dispensing
flexible sheet
material includes a support for rotatably supporting a roll of sheet material,
a feed
mechanism for advancing the sheet material from the roll, and a motor for
driving the
feed mechanism. A structure defines a discharge chute of the dispenser
downstream
of the feed mechanism. A sensor is provided for detecting the presence and
absence
of sheet material in the discharge chute and outputting respective first
signals
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indicative thereof. A proximity sensing system including an RF antenna is
provided
for detecting the presence of a user's hand in close proximity to the
dispenser, and
outputting a second signal indicative thereof. A control device is provided
for
receiving the respective first signals, and the second signal, and for
controlling the
motor to selectively drive the feed mechanism in response thereto. The sensor
is
mounted on a first printed circuit board mounted on the structure adjacent to
the
discharge slot. The antenna is mounted on a second printed circuit board
mounted on
the structure and positioned in overlying relation to the first printed
circuit board.
[26] According to a sixth one of the inventions, a dispenser for dispensing
flexible sheet
material includes a support for rotatably supporting a roll of sheet material.
A feed
mechanism is provided for advancing the sheet material from the roll. A motor
is
provided for driving the feed mechanism, and a structure defines a discharge
chute of
the dispenser downstream of the feed mechanism. A transfer mechanism is
provided
for contacting a leading segment of sheet material extending from a roll, and
for
moving the sheet material into a feed nip of the feed mechanism. A sensor is
provided for detecting the presence and absence of sheet material in the
discharge
chute and outputting respective signals indicative thereof. A control device
is
provided for receiving the respective signals, and for controlling the motor
to
selectively drive the feed mechanism in response thereto, to dispense a
predetermined
length of the sheet material from the point at which a leading edge portion is
detected
by one of the plurality of sensors. The control device further determines,
based upon
the signals, a condition wherein a working roll of sheet material is either
absent or
depleted, and in response to that determination controls the transfer
mechanism to
attempt a transfer of feed to a new roll of sheet material.
[27] According to a seventh one of the inventions, a dispenser for dispensing
flexible sheet
material includes a support for rotatably supporting a roll of sheet material,
a feed
mechanism for advancing the sheet material from the roll, and a motor for
driving the
feed mechanism. A plurality of sensors are spaced along a width of the sheet
material
for detecting respective leading edge portions of the sheet material and
outputting
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respective signals indicative thereof. A control device is provided for
receiving the
respective signals and controlling the motor to drive the feed mechanism to
dispense a
predetermined length of the sheet material from the point at which a leading
edge
portion is first detected by one of the plurality of sensors.
[28] According to an eighth one of the inventions, a dispenser for dispensing
flexible sheet
material includes a support for rotatably supporting a roll of sheet material,
a feed
mechanism for advancing the sheet material from the roll, and a motor for
driving the
feed mechanism. A sensor is provided for detecting a leading edge portion of
the
sheet material and outputting a signal indicative thereof. A measurement
device is
provided for measuring a first interval of advancement of the feed mechanism
teizninating with a detection of a leading edge portion by the sensor. A
control device
is provided for receiving signals from the sensor and the measurement device,
and for
controlling the motor to drive the feed mechanism to dispense a predetermined
length
of the sheet material from a determined initialization point. The control
device
includes a storage device for storing a nominal measure of the first interval
of
advancement, a comparator for comparing a measurement of the measurement
device
with the nominal value, and determination means for determining the
initialization
point for a given dispense cycle based upon an output of the comparator.
[29] According to a ninth one of the inventions, a dispenser includes a
housing having a
discharge opening. A support is provided within the housing for supporting a
continuous strip of sheet material having a plurality of spaced tear lines
defining
leading and trailing edges of individual removable segments, with an outer
segment
having a free leading edge and inner segments which in turn become outer
segments
as adjoining outer segments are removed. A feed mechanism is provided for
repeatedly moving the sheet material in advancement and retraction intervals.
The
advancement intervals serve to advance successive outer ones of the segments
through the discharge opening and out of the housing. The retraction intervals
serves
to initialize the sheet material for the advancement interval. A sensor is
provided for
repeatedly detecting arrival of a leading edge of retracting sheet material at
a first
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position defining the end of the retraction interval and the beginning of the
advancement interval, as sheet material is repeatedly retracted back into the
discharge
opening. A control device is provided for receiving a signal from the sensor
indicating an arnval of a leading edge at the first position, and for
initiating the
advancement interval from the first position. The advancement interval
terminates
when the leading edge of the sheet material has advanced from the first
position a pre-
determined amount, to repeatedly place the spaced tear Iines at a second
position that
is variable downstream of the first position in relation to variations in the
lengths of
the segments. The second position defines the beginning of a retraction
interval for a
next adjacent segment, when it is in turn initialized for an advancement
interval.
[30] According to a tenth one of the inventions, a dispenser for dispensing
flexible sheet
material from a roll includes a chassis defining a web discharge opening and a
feed
mechanism for advancing the sheet material to the discharge opening. A
detection
system is provided for detecting an absence of sheet material within the feed
mechanism. A transfer mechanism is provided for contacting a leading seg-~nent
of
sheet material extending from a roll and moving the sheet material info a feed
nip of
the feed mechanism. The transfer mechanism includes a transfer member biased
toward the feed nip and into contact with the leading segment of sheet
material. A
transfer link is movable between a first position wherein the transfer link
retains the
transfer bar away from the feed nip, against the bias, and a release position
wherein
the transfer link permits the transfer member to move toward the feed nip
under the
bias and into contact with the leading segment of sheet material. An actuator,
e.g., a
motor, is provided for driving the transfer link from the first position to
the release
position. Control means are provided for electrically activating the actuator
to drive
the transfer link from the first position to the release position in response
to the
detection system detecting an absence of sheet material within the feed
mechanism.
[31] According to an eleventh one of the inventions, a dispenser for
dispensing flexible
sheet material includes a chassis defining a gap for passage of a sheet
material roll
core therethrough. At least one finger-operable, releasable support mechanism
is
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connected to the chassis for rotatably supporting the core above the gap. The
support
is movable from a core retention position to a core release position for
releasing the
core into the gap. A dispenser cover is movably mounted to the chassis for
movement
between a closed position and an open position. The cover is situated, when in
the
open position, to receive a core dropped through the gap.
[32] In a twelfth one of the present inventions, a proximity sensor circuit
includes an
antenna, an oscillator circuit and an automatic sensitivity control circuit.
The antenna
has a baseline stray capacitance. The oscillator circuit is coupled to the
antenna and
generates an oscillation signal having a predetermined oscillation amplitude
corresponding to the baseline stray capacitance of the antenna. Preferably,
the
oscillator circuit has a Colpitts oscillator-type topography. The oscillation
amplitude
of the oscillation signal increases in response to an increase in stray
capacitance from
the baseline stray capacitance of the antenna and decreases in response to a
decrease
in stray capacitance from the baseline stray capacitance of the antenna. The
automatic
sensitivity control circuit is coupled to the oscillator circuit and detects a
change in the
oscillation amplitude of the oscillator signal.
[33] According to preferred embodiments of this invention, the automatic
sensitivity
control circuit controls the amplitude of the oscillator signal by controlling
a current
in the oscillator circuit, thereby counteracting a change in stray capacitance
from the
baseline stray capacitance of the antenna and maintaining the oscillation
amplitude of
the oscillator signal at the predetermined oscillation amplitude, to provide a
substantially constant sensitivity to changes in stray capacitance from the
baseline
stray capacitance of the antenna. The proximity sensor circuit preferably
generates a
detect signal when the automatic sensitivity control circuit detects an
increase in the
oscillation amplitude of the oscillator signal, such as when a hand is placed
in
proximity to the antenna. A shield is preferably coupled to and driven by the
oscillator circuit, thereby reducing the baseline stray capacitance of the
antenna by an
amount that may be about two orders of magnitude greater than an increase in
stray
capacitance sensed by the proximity sensor circuit for generating the detect
signal.
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[34] In a thirteenth one of the present inventions, a method is provided for
providing
substantially constant sensitivity for sensing changes in a baseline stray
capacitance to
an antenna. According to this invention, an oscillation signal is generated by
an
oscillator circuit, preferably having a Colpitts oscillator-type topography,
and coupled
to the antenna. The oscillation signal has a predetermined oscillation
amplitude
corresponding to the baseline stray capacitance of the antenna. The
oscillation
amplitude of the oscillation signal increase in response to an increase in
stray
capacitance from the baseline stray capacitance of the antenna and decreases
in
response to a decrease in stray capacitance from the baseline stray
capacitance of the
antenna. A change~in the oscillation amplitude of the oscillator signal is
preferably
detected and the amplitude of the oscillator signal is preferably controlled
by
controlling a current in the oscillator circuit to counteract the detected
change in stray
capacitance from the baseline stray capacitance of the antenna. The
oscillation
amplitude of the oscillator signal is maintained at the predetermined
oscillation
amplitude to provide a substantially constant sensitivity to changes in stray
capacitance from the baseline stray capacitance of the antenna. A detect
signal is
preferably generated when an increase in the oscillation amplitude is
detected, such as
when a hand is placed in proximity to the antenna. The oscillator circuit may
include
a shield that is driven with a signal related to the oscillation signal,
thereby reducing
the baseline stray capacitance of the antenna by an amount that may be about
two
orders of magnitude greater than an increase in stray capacitance that
generates the
detect signal.
[35] According to a fourteenth one of the inventions, a dispenser for
dispensing flexible
sheet material from a roll includes a support for rotatably supporting a roll
of sheet
material having a plurality of spaced apart tear lines defining individual
segments of
sheet material, a feed mechanism for advancing sheet material from the roll,
and a
motor for driving the feed mechanism. A transfer mechanism is provided for
transferring a leading portion of a leading segment of the sheet material into
the feed
mechanism, such that the leading portion is folded over during the transfer to
form a
folded-over edge portion. A sensor is provided for detecting a leading edge of
the
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sheet material. A control means is provided for controlling application of
power to
the motor to drive the feed mechanism so as to carry out dispensing operations
wherein predetermined lengths of sheet material are dispensed from leading
edges of
the sheet material detected by the first sensor. The control means further
controls
operation of the transfer mechanism. In a first dispensing operation carried
out by the
control device following an operation of the transfer mechanism, the control
device
controls the motor so as to carry out an initial dispensing operation wherein
a first
predetermined length of sheet material is dispensed from the point at which
the
leading edge is detected by the sensor, and to carry out subsequent dispensing
operations wherein a second predetermined length of sheet material larger than
the
first predetermined length is dispensed from the point at which subsequent
leading
edges are detected by the sensor, the difference between the first
predetermined length
and the second predetermined length corresponding approximately to a length of
the
folded-over portion, such that a tear line between the first segment of sheet
material
and a second segment of sheet material is, following the initial dispensing
operation,
positioned between the feed mechanism and the first sensor, and subsequent
tear lines
between subsequent segments of the sheet material are positioned between the
feed
mechanism and the first sensor, following subsequent dispensing operations.
[36] According to a fifteenth one of the inventions, a dispenser for
dispensing flexible
sheet material includes a chassis, a support for rotatably supporting a roll
of sheet
material within the chassis, a feed mechanism for advancing the sheet
material, and a
motor for driving the feed mechanism. A dispenser cover is movably mounted
with
respect to the chassis for movement between a closed position and an open
position.
The cover has a surface defining a dispensing slot. The surface moves into
overlying
registry with a discharge slot-defining portion of the chassis when the cover
is moved
into the closed position such that a leading segment of sheet material
extending from
the discharge slot when the cover is in the open position may become lodged
between
the cover and the chassis when the cover is moved to the closed position. A
sensor
for sensing when the cover is in the open position and when the cover is in
the closed
position. The sensor outputs a signal indicative thereof. A control device is
provided
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for controlling the motor to drive the feed mechanism so as to dispense a
predetermined length of the sheet material in response to the sensor
indicating that the
cover has been moved to the closed position. The predetennined length of sheet
material is sufficient to cause a leading segment of sheet material lodged
between the
chassis and the cover to loop out of the dispensing slot formed in the cover.
[37] The above and other objects, features and advantages of the present
inventions will be
readily apparent and fully understood from the following detailed description
of
preferred embodiments, taken in connection with the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[38] Figure 1 is a perspective view of a roll towel dispenser embodying many
of the
present inventions, with a cover thereof pivoted to an open position.
[39] Figure 2 is a perspective view of a chassis assembly of the dispenser
shown in Fig. 1,
with parts exploded therefrom.
[40] Figure 3 is a rear side perspective view of the chassis assembly and
parts shown in
Fig. 2.
[41] Figure 4 is a right side elevational view of the dispenser shown in Fig.
1, with the
cover thereof pivoted to an open position.
[42] Figures 5 and 6 are pautially broken-away close-up side elevational views
of a
releasable drive mechanism of the dispenser shown in Fig. 1, in engagement and
disengagement, respectively, with a driven gear of a feed mechanism of the
dispenser.
[43] Figure 7 is an exploded perspective view of the releasable drive
mechanism of Fig. 5.
[44] Figure 8 is a diagrammatic perspective view showing, in isolation, the
releasable drive
mechanism engaged with the driven gear.
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[45] Figure 9 is a partially broken-away left side elevational view of the
dispenser shown
in Fig. 1, with the cover thereof pivoted to an open position and a roll core
contained
within the cover.
[46] Figure 10 is a cross-sectional view taken on line 10-10 in Fig. 9,
illustrating an
inventive power line input port/battery compartment lock-out arrangement.
[47] Figure 11 is an exploded view of a front shield assembly of the dispenser
shown in
Fig. 1, including overlying printed circuit boards providing, respectively,
mounting
surfaces for a pair of sheet detection sensors, and a proximity sensing system
antenna.
[48] Figure 12 is a cross-sectional view taken on line 12-12 in Fig. 11,
showing a
discharge chute of the dispenser.
[49] . Figure 13 is a diagrammatic front elevational view of a leading segment
of sheet
material extending within the discharge chute of Fig. 12 and out of the
dispenser,
illustrating various "tabbing" scenarios.
[50] Figure 14 is a perspective view showing, a powered web feed transfer
mechanism of
the dispenser of Fig. 1 in relation to the feed and pressure rollers of the
dispenser.
[51] Figure 15 is a side elevational view of the web feed transfer mechanism
and feed
mechanism of Fig. 14.
[52] Figures 16A-16E are diagrammatic side elevational views showing,
sequentially,
operation of an alternative web feed transfer mechanism providing a powered
release
of a sprang biased transfer bar.
[53] Figure 17 is a top plan view of the dispenser shown in Fig. 1, with the
cover thereof
pivoted to the open position.
[54] Figure 18 is a cross-sectional view illustrating a finger releasable roll
core support
mechanism in accordance with one of the present inventions.
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[55] Figure 19 shows a schematic diagram of a proximity sensor system used for
sensing
the proximity of a user's hand, according to one of the present inventions.
[56] Figure 20 is a block diagram of an electrical control system that may be
implemented
in the dispenser of Fig. 1.
[57] Figure 21A and 21B are respective parts of a control flow diagram for
program logic
that may be implemented in conjunction with the electrical control system of
Fig. 20.
[58] Figure 22 is a bottom plan view of the dispenser of Fig. 1, with the
cover thereof
pivoted to a closed position.
[59] Figure 23 is a diagrammatic side elevational view of the dispenser of
Fig. l,
illustrating a loop of sheet material generated upon cover closure, in
accordance with
one of the present inventions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[60] Referring first to Figs. 1-3, a paper towel dispenser I according to the
present
invention comprises a chassis assembly 3 that includes a right side chassis
member 5,
a left side chassis member 7, and a middle chassis member 9 extending between
the
side chassis members. Dispenser 1 further includes a back panel member 11 and
a
pivotal front cover 13 attached, by a pin 15, hinge or other convenient
attachment
mechanism, to back panel member 11. Front cover 13 may be opened and pivoted
away from chassis assembly 3 to a web loading position (as shown) allowing a
roll I7
of a web material 18 to be loaded into dispenser 1.
[61] In the illustrated exemplary embodiment, roll 17 comprises a continuous
web 18 of
flat segments of paper towel material wound upon a hollow cylindrical core.
Dispenser 1 could, of course, dispense other flexible webs, paper or
otherwise. The
web could, e.g., be in the form of folded sheet segments wound onto a roll and
separable from each other along lines of perforation to form folded napkins.
In the
illustrated preferred embodiment, web 18 of roll 17 includes a series of
spaced apart,
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transverse tear lines 19 (one shown) which subdivide the web into flat sheet
(towel)
segments of a predetermined length. Roll 17 is rotatably supported between an
upper
pair of supports. One of the supports comprises an inwardly directed hub 21
attached
to the free end of a spring arln 23 extending upwardly and inwardly along an
inside of
right side chassis member 5 from a cantilever mounting point 25. An opposite
hub 27
(see Fig. 3) protrudes inwardly directly from an inside of left side chassis
member 7.
Each inwardly directed hub 21, 27 is loosely received within a core of roll I7
to
permit free rotation of roll 17. Of course, numerous other roll mounting
arrangements
could also be used.
[62] To load a roll into dispenser 1, the attendant first opens front cover I3
to the position
shown in Fig. 1. Dispenser 1 is designed to accommodate a working roll and a
reserve roll. In the interest of dispenser size reduction, the space defined
between a
lower pair of roll supports 29, 31 of dispenser I is restricted such that a
full roll (as
may be positioned in the upper pair of supports) cannot be placed therein
until after it
has been depleted by about 60%. At such time, the partially depleted working
roll
(now a stub roll) may be transferred by an attendant to lower set of supports
29, 31.
As will be described in detail, this can be done while a leading portion of
the towel
web remains fed through the dispenser feed mechanism. Thereafter, a new
(reserve)
roll may be loaded into the upper pair of roll supports. In other possible
embodiments
(having a larger space defined between lower roll supports 29, 31), the
attendant can
have the option to initially load both rolls into the dispenser at the same
time.
[63] Middle chassis member 9 provides forms a foundation for a feed mechanism
serving
to dispense web I8 from roll 17 in incremental sheet segments. While the feed
mechanism could be driven by a lever or the like, it is preferably (and is
shown)
driven by an electric motor, generally in the manner described in copending
application Serial No. 09/081,637. In the illustrated preferred construction,
the feed
mechanism includes a mating feed (dove) roller 33 and pressure roller 35 which
cooperate to dispense the web material. Feed roller 33 and pressure roller 35
are
mounted upon axles rotatably supported at their ends by side chassis members
5, 7.
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Pressure roller 35 is preferably biased against feed roller 33 by a spring
(not shown)
to define a feed nip 37. A gear (or other drive rnernber) secured to a drive
shaft of the
motor is engageable with a driven gear (or other driven member) secured to an
axle of
feed roller 33 to rotate the same. When web 18 is fed into nip 37, rotation of
feed
roller 33 causes web 18 to be advanced through nip 37, around feed roller 33.
Middle
chassis member 9 provides at its rear side an arcuate guide plate 39 (see Fig.
3) to
direct web 18 about the rear side of feed roller 33 and into a discharge chute
41 (see
Fig. 12) formed between middle chassis member 9 and a face plate structure 43
attached thereto (seen in its entirety in Fig. 2). A discharge opening 45 is
formed
between a bottom forward edge of middle chassis member 9 and a corresponding
lower portion of face plate structure 43 (see Figs. 22-23).
Releasable Feed Roller Drive Mechanism
[64j Referring to Figs. 4-8, a feed roller drive mechanism 47 according to the
present
invention is now described in detail. Drive mechanism 47 generally includes an
electric motor 49, a drive member (in this case, a worm gear 51) and a carrier
53.
Motor 49 is retained within carrier 53 and has a drive shaft 55 to which worm
gear SI
is attached. Carrier 53 is pivotally connected to an outside of right side
chassis
member 5, in a manner permitting worm gear 51, which is also retained by
carrier 53,
to be moved into and out of driving engagement with a driven member (in this
case, a
spur gear 57) of feed roller 33. In an engagement position, worm gear 51 mates
with
spur gear 57 for driving the same. A worm gear/spur gear set as illustrated
provides a
quiet, smooth and compact output system. In addition, by its inherent design,
worm
gear 51 cannot be driven by spur gear 57. This one-way drive set-up
advantageously
avoids an overdrive of the feed mechanism due to a user pull on a leading
segment of
the sheet material being dispensed. Utilization of a worm gear also allows the
motor
drive shaft 55 to be oriented orthogonally with respect to feed roller 33,
which allows
for a more compact dispenser design; it also permits easy
engagement/disengagement
with spur gear 57. Other meshing gear sets may be used, as may other known
means
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for transmitting rotary motion from one shaft to another, such as pressure
rollers,
belts, etc.
(65] A pivotal mount of carrier 53 to right side 'chassis member 5 allows
motor 49, drive
shaft 55 and worm gear 51 to rotate as a unit into and out of driving
engagement with
spur gear 57, as shown by the arrow in Fig. 4. Although carrier 53 is shown
pivotally
attached to right side chassis member 5, carrier 53 may be translatably or
otherwise
movably mounted to side chassis member 5, or to other suitable structure of
dispenser
1.
[66] As best seen in Fig. 7, the pivotal carrier mount is provided by a
cylindrical sleeve 59
attached to a lower forward corner of a main body portion 61 of carrier 53.
Sleeve 59
extends parallel to feed roller 33, and orthogonal to drive shaft 55 and
attached worm
gear 51. A bolt, screw rivet or like fastener 63 is passed through sleeve 59
and
connected to right side chassis member 5 to provide a carrier pivot axis
extending
within and along sleeve 59. Obviously, other known rotatable mounting
arrangements may be used.
[67] A spring clip arrangement 65 provides a releasable hold mechanism for r
emovably
holding carrier 53 in a position, as shown in Fig. 5, wherein worm gear 51 is
placed in
driving engagement with spur gear 57. Spring clip aiTangement 65 is manually
releasable (preferably forger operable) to allow carrier 53 to rotate worm
gear 51 out
of engagement with spur gear 57. As illustrated, spring clip arrangement 53
includes
a spring arm 67 extending forwardly from an upper part of carrier body portion
6I,
and a stationary (female) retention clip 69 attached to an adjacent wall
surface of right
side chassis member 5. The free end of spring arm 67 forms a (male) catch
member
71 insertable into retention clip 69. Catch member 71 is offset relative to a
primary
lever portion 72 of spring arm 67 so as to form at its rear side a shoulder
73. On its
front side, catch member 71 arcs downwardly such that a leading edge thereof
is
situated below the lever portion 72.
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[68] As illustrated, female retention clip member 69 is formed as a U-shaped
frame
attached to side chassis member S to thereby form a generally rectangular
opening
that receives male catch member 6S. As catch member 6S is advanced into female
clip member 69, the upper arcuate surface of catch member 71 slidably engages
the
top inner surface of clip member 69. A cam action causes spring ann 67 to
elastically
deflect downwardly, thereby permitting catch member 71 to continue to advance
into
clip member 69. Once fully inserted, an upper downstream edge 7S of the
rectangular
frame acts as a latch surface that engages with shoulder 73. This engagement
may be
readily manually released by an attendant using his/her finger 77 to press
downwardly
on male clip melnber 69, to thereby elastically deflect spring arm 67
downwardly. As
shown in Fig. 8, a scored, knurled or otherwise textured surface can be
provided on
the top side of catch member 71 to increase the friction between a pressing
finger and
catch member 71 to thereby facilitate a releasing displacement of spring arm
67.
[69] Referring to Fig. 7, carrier body portion S3 defines a motor chamber 79
and a drive
member chamber 81. A dividing wall structure 83 separates the two chambers and
has a hole 8S formed through it. Drive member chamber 81 is defined between
dividing wall structure 83 and an opposite end wall structure 87. A second
hole 89 is
formed in end wall structure 87, in alignment with hole 8S. Drive shaft SS
extends
through, and is rotatable within, aligned holes 8S and 89. Dividing wall
structure 83
and end wall structure 87 thus serve to rotatably support drive shaft SS.
Motor 49 and
drive shaft SS may be restrained from backing out of carrier S3 by suitable
means
such as an e-clip 91 or other retention device fixedly secured on the end
drive shaft
SS, outside of (and below) end wall structure 87.
[70] Worm gear S 1 is coaxially fixed on motor drive shaft SS between dividing
wall
structure 83 and end wall structure 87. To permit driving engagement of worm
gear
S1 and spur gear S7, the sidewall wall structure defining drive member chamber
81
forms a side port 93 sized and positioned to allow ingress and egress of a
portion of
spur gear S7 to/from carrier S3 as carrier S3 is rotated into and out of its
engagement
position.
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[71] Releasable drive mechanism 47 facilitates the clearing of jams that may
occur in
operation of dispenser 1, by permitting ready disengagement of feed roller 33
from
motor 49. This functionality is accomplished with a simple structure having
few
parts, which are easily assembled. Carrier 53 may be injection molded as a
unitary
thermoplastic component. Motor 49, drive shaft 55 and worm gear 51 are readily
engaged with each other and within carrier 53 to complete the mechanism.
[72] An attendant can readily disengage drive mechanism 47 by pressing
downwardly on
catch member 71 to deflect spring arm 67 such that catch member 71 is released
from
retention clip 69. Carrier 53 is then pivoted such that worm gear 51 moves out
of
engagement with spur gear 57. The attendant may then rotate feed roller 33
and/or
pressure roller 35 as necessary to clear a jarn. Once the jam is cleared,
dispenser 1
may be restored to an operative state by simply re-engaging worm gear 51 with
spur
gear 57, by rotating carrier 53 in the opposite direction until catch member
71 is
reengaged with female clip member 69. In contrast, with known motorized
dispensers
lacking provision for ready disengagement of the drive motor from the feed
roller,
jams must be removed with the motor engaged, or a complicated procedure must
be
undertaken to disengage the drive motor and feed roller. Left engaged, a drive
motor
may impart significant additional drag inhibiting free rotation of the feed
roller. As a
result, manual rotation of the feed roller to remove a jaln of web material
may be
rendered more difficult. As previously explained, utilizing a worm gear in the
drive
train as in the present system precludes manual rotation of the feed roller
without
disengagement of the drive motor.
Power Supply System
[73~ Refen-ing now to Figs. 9-10, a power supply system of dispenser 1
includes a battery
compartment 95 and a power line input port 97: Power line input port 97 and
battery
compartment 95 are configured to provide power to the electrical systems and
components of dispenser l, to the mutual exclusion of each other.
Specifically,
battery compartment 95 can only receive a full complement of batteries (to
complete a
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power supply circuit) when power line input port 97 is not connected to a
power
line/plug 99. Conversely, power line input port 97 can only receive a power
line plug
99 when battery compartment 95 is not fully loaded arid operatianal.
[74] As shown, battery compartment 95 is integrally formed as part of left
side chassis
member 7 to receive standard size batteries, e.g., D-size dry cells, arranged
in a series
connection between a pair of terminals 101, 103. The compartment is closeable
by
way of a removable cover 105. Power line input port 97 is located directly
adjacent to
battery compartment 95, at a lower side thereof. Access to port 97 is
provided,
preferably exclusively, through (from the inside of) battery compartment 95.
In the
illustrated exemplary embodiment, power line input port 97 is a conventional
DC
input jack designed to receive output plug 99 of a conventional AC/DC power
converter (adapter).
[75] In accordance with the invention, power line input port 97 is configured
relative to
battery compartment 95 such that a power line 105 when extending to plug 99 is
engaged with power line input port 97 extending from plug 99 naturally
occupies a
portion of battery compartment 95 and thereby precludes insertion of one or
more
batteries into the compartment. Conversely, when battery compartment 95 is
fully
loaded with batteries, access to power line input port 97 is blocked and part
97 is
prevented from being connected to power plug/line 99, 105.
(76] The above-described power supply arrangement of dispenser 1 provides a
facility
owner/operator with the option to choose two dispenser power sources --
battery and
line power. This allows greater flexibility in the use and location of the
dispenser. At
the same time, potential damage to or malfunction of the dispenser electronics
or
alternative power supplies, due to inadvertent simultaneous connection of the
alternative power supplies in parallel with each other, is avoided. A reliable
power
lock-out functionality is provided with a simple and inexpensive mechanical
arrangement.
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[77j As a further safeguard, battery compartment 95 and selected terminals
thereof lnay be
configured to prevent connection of the batteries with the wrong polal-ity.
For
example, terminal 101, if set to be a positive terminal, may be inset slightly
relative to
adjacent flanking shoulders 102 such that only the protruding positive
terminal of the
battery (e.g., D-size dry cell) will make contact with terminal 101. If the
battery is
inserted with the wrong (reverse) orientation, the flat negative battery
terminal will
abut against shoulders 102 and remain spaced from (and out of electrical
contact with)
terminal 101. Similar terminal arrangements may be provided at any of the
other
positive terminals within battery compartment 95.
Dispenser Set-up and Dispensing Control
[78] Upon engagement of drive mechanism 47, and the provision of power (via
battery
compartment 95 or power line input port 97), dispenser 1 need only be loaded
with a
roll of the sheet material to be readied for use. As with the dispenser
described in
application Serial No. 09/081,637, dispenser 1 is preferably used for
dispensing from
a roll of web material having spaced apart tearing lines, such as prescored
lines of
perforation, resulting in sheet segments of a desired length, e.g., nine
inches. By using
a pre-perforated web material, the sheet segments can be easily separated from
the
web without requiring cutting. The perforation tensile strength can be made
light
enough such that the web material can be easily separated along the
perforation lines.
By power feeding web 18 and providing pre-formed tear lines, the web does not
need
to have sufficient strength to draw out additional portions as a leading
portion is
removed (as required by many known dispensers), and less pull force is
required to
detach a leading segment. Thus, the paper or other material of which the web
is made
can be better optimized for softness and absorbency.
[79] When a roll 17 (see Fig. 1 ) is initially loaded into dispenser 1, the
leading edge of web
18 may be manually fed rearward into feed nip 37 formed between feed roller 33
and
pressure roller 35. Preferably, however, a feed transfer mechanism (as will be
described) is utilized, such that it is only necessary for the attendant to
place a leading
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edge portion of the web in a cradle 107 formed by face plate structure 43 (see
Figs. I
and 23). When front cover 13 is closed, a cover switch I09 (see Figs. 1 and
20) may
be engaged to activate drive mechanism 47 and automatically drive feed roller
33 in a
direction (i.e., counterclockwise as viewed in Fig. 4) to advance the web
around feed
roller 33 and into discharge chute 41 (see Fig. 12) formed below feed roller
33,
between middle chassis member 9 and face plate structure 43.
[80] In the event a feed transfer mechanism is utilized, closure of cover 13
may also
actuate the feed transfer mechanism, to press a leading edge portion of web
18, which
is draped over feed nip 37 and retained in cradle 107, into feed nip 37 as
feed roller 33
is driven by drive mechanism 47. The leading edge of web 18 is advanced, and
ultimately detected by one or both of a pair of towel sensors 111, 113 (see
Figs. 11-
13) positioned to sense the presence of sheet material in discharge chute 41.
Sensors
111 and 113 are coupled with a microprocessor 115 (see Fig. 20) forming part
of a
micro-controller or the like, which is programmed to detect as a leading edge
of
dispensed web material, a transition from a web absent to a web present
condition.
Once a leading edge has been detected in this manner, microprocessor 115
causes
drive mechanism motor 49 to continue to run for a second interval, initialized
at the
point of leading edge detection, to dispense a predetermined length of towel.
Removal of the leading sheet segment places a next leading edge of web 18 in
discharge chute 41, downstream of the feed mechanism, but upstream of sensors
111,
113. While the sensors could be any one of a variety of suitable mechanisms,
for
example, mechanical limit switches or acoustical sensors, the illustrated
preferred
embodiment utilizes a pair of optical sensors 111, 113, each comprising an
emitter
115 and a photo-detector 117, e.g., a photo-diode or photo-transistor (see
Fig. 12).
Light emitted from emitter 115 is reflected and received by associated photo-
detector
117 in a certain intensity when web material is present. This intensity is
reflected in
the output signals of the photo-detectors 117, which are supplied to
respective input
pins of microprocessor 115.
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[81] Referring to Figs. 12 and 23, discharge chute 45 preferably defines an
access that is
narrow enough to prevent a user's fingers from reaching a free leading edge of
web
18 located therein, e.g., while dispenser 1 is waiting for a sheet request
signal
generated by a user proximity sensor (to be described). Sensors I 11, I 13 are
located
in discharge chute 41 between discharge outlet 45 and the upstream blind end
119
(see Fig. 23) of chute 41 defined by a feed-through formed between feed roller
33 and
an arcuate guide plate 121 of middle chassis member 9. With this arrangement,
towel
sensors 111, 1I3 are substantially shielded from ambient light and potential
interference caused thereby. Adverse effects caused by ambient light can be
further
minimized by pulsing the emitter and high-pass filtering the output of the
photo-
detector, under the control of microprocessor 115. In conjunction with pulsing
the
emitter, microprocessor 115 can be used to carry-out known synchronous
defection
techniques to further filter out any motor brush and optical noise from the
photo-
detector output, which may not be removed by the high-pass filtering. Such a
technique may involve subtraction of a value representative of a photo-
detector On
time when the emitter is Off, from a photo-detector On time when the emitter
is
pulsed On. This can be done digitally, by decrementing and incrementing a
stored
count value, or using analog techniques, e.g., by charging and discharging a
capacitor.
[82] By appropriately controlling the feed of web 18, successive perforation
lines 19 are
located in discharge chute 41 such that each leading sheet segment can be torn
away
from the remaining web 18, leaving a new free leading edge (formerly an intact
perforation line 19) slightly above the towel sensing location of sensors 111,
113.
The (new) free leading edge will remain there until the next dispensing
operation is
carried out. As mentioned, this may be upon receipt by microprocessor I45 of a
sheet
request signal generated by a user proximity sensor (to be described).
Alternatively,
in a "sheet hanging" mode, a sheet segment may be immediately dispensed upon
the
sensing of an absence of sheet material in the discharge chute, by sensors
111, 113.
Either way, towel sensors 111, 113 will register the position of the leading
edge
shortly after the feed mechanism starts feeding sheet forward, and before a
second
predetermined interval of advancement is carried out. As an alternative to
carrying
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out the frst interval of advancement as a frst step upon receipt of a sheet
request, the
first interval may be carried out inunediately following removal of a sheet
segment
dispensed in a preceding dispense cycle. In this case, the free leading edge
begins the
second predetermined interval of advancement immediately upon receipt of a
sheet
request signal, initialization of the leading edge having been previously
performed.
[83] In lieu of triggering a second predeteumined internal of advancement by
the direct
sensing of a segment leading edge (free or otherwise), one or more web sensors
could
be utilized to detect indicia (e.g., a mark or the like) located in relation
to a leading
edge. In this case, detection of the indicia by the sensors) would indicate
arrival of
the leading edge at a first position spaced from the sensor, marking the end
of the frst
interval of advancement and the beginning of the second predetermined interval
of
advancement.
[84.] As a further variation, a dispense cycle may comprise an interval of
sheet
advancement and a sheet retraction interval. More specifically, a first
interval of
advancement may be used to dispense a leading segment and to place the adj
acent tear
line downstream of the sensors) a short distance. Once the leading segment is
removed, an interval of retraction may begin and continue until the sensors)
detect
the free leading edge (e.g., as a transition from a web present to a web
absent
condition). This interval of retraction serves to initialize the start of the
next interval
of advancement, to be carried out in a subsequent dispense cycle. In this
embodiment, a switch or sensor separate from sensors 111, 113 may be used to
detect
removal of the leading segment by a user, and control circuitry/logic may be
provided
for providing alternating forward and reverse drive cycles of feed roller
drive motor
49.
[85] Dispensed web exits discharge chute 41 through discharge outlet 45 where
it hangs
externally of dispenser 1. A user may grasp the dispensed sheet segment and
pull on
it, causing it to tear off along the adjacent perforation line 19 (see Fig. 1)
positioned
upstream of sensors 111, I13. This returns sensors 111, 113 to a web absent
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condition. If a sheet segment is dispensed, but the user does not remove it,
sensors
111, 113 will ordinarily both detect the presence of web 18. In this case,
microprocessor 115 will preferably prevent further activation of motor 49.
Such feed
inhibition serves to discourage abusive excessive dispensing, as well as to
prevent
potential inadvertent triggering of a dispensing operation, e.g., as a result
of spurious
signals generated by a user detection sensor (and interpreted as a sheet
request signal).
In addition, energy savings may be realized by activating and monitoring
(e.g.,
polling) the user detection sensor only when sensors 111, 113 indicate a web
absent
condition. The pair of sensors 111, 113 spaced across the width of web
material 18
are advantageously utilized to cause activation of motor 49 to carry out a
dispense
cycle in the event the leading towel segment is irregularly torn apart from
the tearing
line, uncovering only one of the two towel sensors. In lieu of a pair of
spaced sensors
11 I, 113, a single centrally positioned sensor may be provided in discharge
chute 41.
[86] With reference to Figs. 11-12, sensors 111, 113 are mounted on an
elongated printed
circuit board (PCB) 123 that clips into and out of a seat defined within a
recess 125 of
face plate structure 43. PCB 123 is retained within recess I25 by a plurality
of bosses
127. Sensors 11 l, I 13 are mounted to face discharge chute 41, adjacent
opposite ends
of PCB 123. Apertures are provided in the floor of recess 125 at positions
corresponding to sensors 111, 113, to provide windows through which the
sensors
may "loole" into discharge chute 41. Signal lines (not shown) extend from
sensors
111, I 13 to a connector 129 attached to the end of a ribbon cable 131 that
extends to a
main circuit board 133 (see Figs. 2 and 9).
[87) As mentioned, microprocessor 115 preferably controls dispenser 1 to feed
a sheet
segment only after detecting that a previously fed sheet segment has been
separated
from the remaining web 18 (and, optionally, only after receipt of a sheet
request
signal from a switch or sensor). To control the amount of web 18 fed so that
only one
sheet segment is fed per dispense cycle, and to assure a proper placement of
successive tear lines in discharge chute 41, dispenser I employs a
displacement
detector 135 (see Fig. 20), the output of which can be used to establish a
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predetermined interval of web feed during each dispensing cycle, i.e., each
time motor
49 is activated. Displacement detector 135 may be a shaft encoder, either
electromechanical or optical, mounted to generate a pulse for each small
increment of
rotation of feed roller 33. In the illustrated exemplary embodiment, an
optical shaft
encoder comprises a slotted wheel 137 mounted on an axle 139 of feed roller
33, in
overlying relationship with main PCB 133 retained within left side chassis
member 7.
A sensor (emitter-photo-detector pair) of the encoder may be mounted on PGB
133 so
as to output a pulse train corresponding to rotation of the wheel slots past
the sensor.
An alternative to encoding successive incremental displacements of feed roller
33 is
to detect the difference in transmissivity of web 18 when a perforation Iine
I9 crosses
an optical interrupter. That is, an emitter-photo-detector combination may be
used to
provide a signal that indicates a first level of light reception as web is
fed, and a
second level when a perforation line crosses the light path. A pulse may be
generated
by the presence of the perforations.
[88] Microprocessor 115 preferably will count the pulses generated by sheet
displacement
detector 135 starting from the point at which a leading edge is detected by
microprocessor 115 (e.g., as transition from a web absent to a web present
condition).
Dispenser 1 may be set to dispense from rolls with sheet segments of various
length.
For instance, with perforated tear lines spaced nine inches apart,
microprocessor 115
counts the corresponding number of pulses to dispense nine inches of web 18. A
switch, dial, button or other means nay be provided to adjust the displacement
per
dispensing cycle to accommodate rolls having different segment lengths, and/or
to
cause dispensing of multiple sheet segments, if desired. Although, other
counting
arrangements, or a time based dispense cycle, could be used for controlling
the
dispense interval, calculation of sheet displacement from a detected leading
edge is
preferred to avoid cumulative error, i.e., error accumulated over a series of
consecutive dispense cycles. Such cumulative error could result in
misplacement of a
tear line for a leading segment, either downstream of sensors 111, I I3, or
upstream of
blind end 119 (see Fig. 23) of discharge chute 41, thus resulting in a system
fault
condition.
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[89] "Overshoot" may occur following an On-interval of motor 49, due to
inertia of the
feed mechanism. To avoid this potential problem, conventional circuitryllogic
can be
provided to directly short the power terminals of the motor at the end of each
operation interval, to thereby provide a known dynamic braking effect.
[90] As a further protective measure, microprocessor 115 may be prograrmned to
compensate for any overshoot that does occur, by subtracting from the desired
displacement amount a predicted or anticipated overshoot amount. An
appropriate
value may be obtained from historical data representative of overshoot amounts
measured as the ~ number of encoder pulses occurring after power-down of the
motor,
e.g., a moving average value. For example, a memory may store, for a
predetermined
number of recent dispense cycles; a moving average of the number of counts of
displacement detector 135 occurring after power-down of motor 49. As a further
example, an updated running average value may be maintained by a recursive
calculation averaging a most recent overshoot count value with a preceding
average
value (which itself was calculated by averaging the penultimate count value
with a
preceding count value, etc.) The running calculation may be initiated upon
power-up
of the dispenser or closure of cover I3, and may continue until operation of
the
dispenser is inten-upted, e.g., by opening of the cover or battery depletion.
A starting
"average" value (for use in the initial dispense cycle) may be chosen based
upon
empirical data.
[91] Accommodation of "Tabbing" With reference now to Fig. 13, it is explained
how the
web sensing system of dispenser I may handle various possible scenarios in
which
tearing occurs other than strictly along tear line I9. Broken lines 141 and
143 both
depict internal "tabbing" tears, that is, tears that result in an irregular
tab of web
material 18 remaining wholly within discharge chute 41, upstream of sensors
111,
1 I3. Broken line 145 depicts an external "tabbing" tear, wherein an irregular
tab of
web material extends over at least one of sensors 111, 113 (and generally
outside of
discharge chute 41). Through utilization of two spaced sensors 11 l, 113, and
as has
been described, removal of a leading segment can be detected notwithstanding
this
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external tabbing condition, by sensing the absence of web material at either
one of the
two sensors. '
[92] Tear line 141 may be said to result in downstream internal tabbing, in
the sense that
the irregular tab that results is downstream of tear line 19 (yet still
upstream of
sensors 111, 113). Tear line 143 may be said to result in upstream internal
tabbing, in
the sense that the irregular tab that results is upstream of tear line 19.
With a single
centrally located web sensor, these two scenarios would not cause a problem,
as the
sensor would be positioned to detect the tear along tear line 19 as the
leading edge,
and initialize further feed fiom that point. On the other hand, these
conditions may
cause a problem when a pair of spaced sensors, such as sensors 111, 113, are
utilized,
in that detection of a leading edge will occur along the irregular tear line
141 or 143
downstream or upstream of tear line 19, with the result that the
initialization of sheet
feed occurs either upstream or downstream of tear line 119; such improper
initialization would result in successive misplacement of subsequent tear
lines.
[93] A "first edge detection" system may be employed to avoid a dispenser
fault condition
arising as a result of upstream internal tabbing. In this system,
microprocessor 115
initializes a second interval of advancement based upon the first edge
detected by
sensors 111, 113, on the assumption that the first detected edge is an edge
formed
along tear line 19. Tabbing that occurs downstream of tear line 19 is
generally of the
"external" kind illustrated with Line 145, leaving a tab which extends
externally of
discharge chute 41, or at least downstream of one of sensors 111, 113, such
that the
sensor at the tabbed side continues to detect the presence of web material. In
this
instance, and as has been described, the uncovering of at least one of sensors
111, 113
(sensor 113 as illustrated in Fig. 13) signals removal of a leading segment of
sheet
material, satisfying a web absent condition for microprocessor 115 to initiate
a
dispense cycle. Upon initiation of a dispense cycle, initialization of the
dispense
counter (for starting the second interval of advancement) occurs upon the same
sensor
detecting a leading edge.
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[94] In accordance with one of the present inventions, microprocessor 115 may
be
programmed to avoid the above-mentioned initialization problem that may arise
as a
result of the internal tabbing scenarios depicted by tear lines 141 and I43. A
memory
may store a nominal measure of the first interval of sheet advancement. This
may be
a constant value, e.g., set to correspond to one half the distance between the
blind
upstream end 119 of discharge chute 41 (see Fig. 23) and sensors III, I13.
Alternatively, the memory rnay store, for a predetermined number of recent
dispense
cycles, a moving average of the number of counts of displacement detector 135
occun-ing from activation up to the point that a leading edge is detected (the
first
variable interval of advancement). The moving average may be computed by other
known techniques, such as recursively in the manner previously described in
connection with prediction of a feed mechanism overshoot amount. The nominal
value (e.g., a set value or a moving average value) may then be compared
against the
count corresponding to a first edge detection by one of sensors 111, 113. If
the latter
count differs significantly from the nominal value, then it may be concluded
that the
detected edge is a bad edge, i.e., one not along tear line 19, in which case
microprocessor may similarly validity check the count corresponding to a
second
edge detection by the other sensor. If the comparison shows that detection to
be valid,
then initialization may be properly carried out from that point. If neither
sensor sees a
good edge, then initialization of the dispense cycle may be carried out at a
point
corresponding to the stored nominal value. In this manner, successive
placements of
tear lines 19 may be properly maintained within discharge chute 41, upstream
of
sensors l l 1, 113, thereby avoiding a dispenser fault condition.
[95] If a user pulls on the leading edge of the sheet segment being dispensed
before the
cycle has been completed, motor 49 may stall due to the increased load placed
on
worm gear 51. (As mentioned, worm gear 51 cannot be reverse driven by spur
gear
57; thus, a user pull will not cause motor 49 to accelerate.) Web I 8
generally will be
prevented from slipping about feed roller 33 when pulled because of the
pinching
engagement of feed nip 37. When the motor stalls, microprocessor 115 may store
the
cumulative displacement (to the point of the stall) and reactivate motor 49 to
dispense
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the remaining portion of the sheet segment after a short pause. Alternatively,
motor
49 may be reversed so that the sheet segment is pulled upstream of towel
sensors 1 I I,
1 I3 and fed forward again to register the leading edge again in preparation
for a new
dispensing cycle.
Dispenser Feed Transfer Mechanism
[96] As previously mentioned, web 18 may be introduced into the feed mechanism
by a
transfer mechanism. With reference to Figs. I, ~, 4, 9 and 14-15, the transfer
mechanism may include a transfer bar 147 pivotally mounted between side
chassis
members 5, 7 and a transfer drive system 149 for driving transfer bar 147 by
way of
an electric transfer motor 151 located within left side chassis member 7.
Transfer
drive system 149 utilizes a series of linkages to convert rotation of the
output shaft of
transfer motor 151 to pivotal movement of transfer bar 147, and fingers 153
thereof,
in the direction of feed nip 37, to position a leading portion of web 18 in
nip 37 while
feed roller drive motor 49 is being operated. Similar to drive motor 49,
transfer motor
15I preferably has low DC power requirements and is powered by batteries
loaded in
compartment 95, or by a line/plug connected to power line input port 97.
Obviously,
a separate power supply for motor 151 could instead be provided.
[97] Under the control of microprocessor 115, transfer motor 151 is preferably
activated in
response to a determination being made either that a working roll is not
present, or
that one that is present is completely depleted. Such a determination may be
made
using sensors 1 I 1, 113 to detect the presence or absence of web 18 within
discharge
chute 41. If a web absent condition is detected and sustained for a
predetermined
operation interval of drive motor 49, this is indicative of the working roll
being
depleted, or the absence of one in the dispenser. Under this condition,
transfer motor
151 is activated to carry out a first transfer attempt. If the first transfer
attempt does
not result in detection by sensors 111, 113 of web material in discharge chute
41, a
second transfer attempt is preferably carried out. If, after the second
transfer attempt,
web material is still not detected, it may be assumed that a reserve roll (to
which feed
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would ordinarily be transferred) is not present in upper roll support hubs 21,
27.
Accordingly, an alarm or indicator, such as a flashing LED 154 (see Fig. 1)
may be
activated to alert the attendant to the need to replenish the dispenser with
roll material.
[98] To facilitate maintenance of a reserve roll in dispenser l, a sensor can
be provided to
detect when a working roll held in the upper pair of supports 21, 27 has been
depleted
sufficiently for it to be moved to lower pair of supports 29, 31. In one
embodiment,
and as shown in Fig. 1, this sensor is provided in the form of a pivotal arm
155 lightly
spring-biased against the outer circumference of the roll placed in the upper
pair of
support hubs 21, 27. Ann 155 may have a pivotal attachment 157 to baclc panel
member 11, and be positioned to actuate a switch that changes state (e.g.,
closes)
when the diameter of the roll is reduced to a certain extent, to activate LED
indicator
154. The switch may, e.g., be incorporated into left side chassis member 7.
Alternatively, in accordance with one of the present inventions, program logic
can be
used in conjunction with microprocessor 115 to determine when the roll has
been
depleted sufficiently for it to be transferred to lower pair of supports 29,
31. For
example, the amount of roll depletion may be determined by subtracting a
cumulative
dispense amount (e.g., calculated from the output of displacement detector
135) from
a stored initial nominal roll length. LED indicator 154 may be activated upon
the
calculated roll depletion reaching or exceeding a stored target transfer
value.
[99] As best seen in Fig. 14, transfer bar 147 is an elongated member having a
plurality of
cross braces that provide extra rigidity. Transfer bar 147 is pivotally
connected to
side chassis members 5, 7 and extends between those members along the length
of
feed nip 37. Transfer bar 147 also includes cover engaging members 157 having
rounded upper shoulders 159 that will slide smoothly along the inside of fiont
cover
13, as cover 13 is closed. Ultimately, engaging members 157 will rest against
the
inside of a front panel of cover 13 to place transfer bar 147 in the set,
transfer ready
position depicted in Fig. 15.
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[100] A pair of sleeve bearings formed at opposite sides of face plate
structure 43 pivotally
support respective stub shafts 161 protruding outwardly from opposite ends of
transfer bar 147. This pivotal mount permits transfer bar 147 to rotate
(counterclockwise in Fig. 15) when cover 13 is pivoted to an open position. In
this
maimer, transfer bar 147 and cover 13 can both rotate to respective web
loading
positions, e.g., as shown in Figs. 1 and 4, in which they are conveniently out
of the
way of the attendant loading the dispenser. The pivotal mount also permits
transfer
bar 147 to rotate about shafts 161 in the direction of nip 37 (cloclcwise in
Fig. 15)
when the transfer drive mechanism is activated, as discussed below.
[101] Rigid transfer fingers 153 are placed along the length of transfer bar
147 for engaging
web 18 and positioning it in the nip 37 formed by feed roller 33 and pressure
roller
35. The number of transfer fingers 153 can be varied depending on the length
of the
transfer bar and/or the strength of the web to be dispensed. With a relatively
weak
web material, a closer spacing of the transfer fingers can be used to reduce
stress
concentrations at the transfer finger contact points, so as to avoid web
perforation or
tearing. As shown, e.g., in Fig. 15, fingers 153 extend away from the transfer
bar in
the direction of nip 37. These fingers 153 include rounded web contacting ends
that
are directed at nip 37 when transfer bar 147 is in its set position. The
forward edge of
each finger 153 is rounded and sized so that it will engage and position web
18
between the rollers 33, 35 without tearing or perforating the web, when
transfer bar
147 is advanced from the set position to the web transfer position.
[102] Referring to Figs. 14-15, the transfer drive system includes an output
gear 163 which
is connected to the output shaft of transfer motor 151, and a transfer gear
165 that
meshes with output gear 163 so that transfer gear 165 will rotate when
transfer motor
151 is operated. Transfer gear 165 forms an arc sector of a circle. A
plurality of gear
teeth are formed along the outer circumference of transfer gear 165. These
teeth mesh
with the teeth of output gear 163. Output gear 163 drives transfer gear 165 in
a
clockwise direction (as shown in Fig. 15) when transfer motor 151 is operated.
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Transfer gear 165 rotates about an axis 167 that is located at the center of
the circle
from which the arc sector of transfer gear 165 is taken.
[103] A rigid transfer link 169 extends between transfer gear 165 and transfer
bar 147 for
imparting movement to transfer bar 147 in relation to the rotation of transfer
gear 165.
Transfer linlc 169 is, at a first end 171, rotatably mounted on an enlarged
inwardly
directed hub portion 173 of transfer gear 165, by a linkage plate 175. Hub
portion
173 is eccentrically located relative to transfer gear rotation axis 167, as
best seen in
Fig. 15. As transfer gear 165 is driven in a clockwise direction by output
gear 163, as
shown in Fig. 15, linkage plate 175 is displaced slightly upwardly and then
rearwardly, following the corresponding translation of eccentric hub 173. Due
to the
freely rotatable mount of linkage plate 175 on hub 173, the clockwise rotation
of hub
175 is not transmitted to transfer lime 169. The first end 171 of transfer
link 169 rises
and moves rearwardly with the translatory movement of linkage plate 175.
[104] At a second end 177, transfer link 169 includes an open bottom hook 179
that engages
a post 181 extending outwardly from one side of transfer bar 147 in the
direction of
one of left side chassis member 7, in spaced relation to the pivot axis of
transfer bar
147. As first end 17,1 of transfer link 169 moves with linkage plate 175 in
response to
rotation of transfer gear 165, hook 179 remains engaged with post 181 and
causes it to
be pulled rearwardly, as transfer link 169 both rotates and translates. As a
result,
transfer bar 147 is rotated about its pivot axis and fingers 153 begin to move
toward
nip 37. With continued rotation of transfer gear 165, transfer bar 147 is
positioned
immediately in front of nip 37 so that transfer fingers 153 contact web 18 and
position
it within nip 37. A resistance to further rotation of transfer gear 165,
resulting from a
pressing contact of fingers 153 against one or both of feed roller 33 and
pressure
roller 35, or resulting from a stop member 183 suitably placed on a backside
of
transfer gear 165 abutting with a suitably placed stop structure 185 of left
side chassis
member 7, can be used to trigger a deactivation of transfer motor 151 by known
means. For example, a high current associated with a stall condition of motor
151 can
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be sensed by appropriate circuitry provided on main PCB 133 (see Figs. 2 and
9) and
used to deactivate motor 151.
[105] As seen in Figs. 14-15, the bottom of hook 179 is open and the front,
inner edge 187
of hook 179 is beveled so that post 181 can move in and out of hook 179
depending
on the positions of front cover 13. Edge 187 forms at its top a peak 189 for
engaging
post 181 and urging it into a seat 191 formed thereabove when transfer link
169
moves toward the rear of dispenser 1 in response to rotation of transfer gear
165.
When cover 13 is opened, post 181 falls out of hook 179 through the open
bottom and
transfer bar 147 rotates downwardly, as discussed below. As cover 13 is
closed, post
181 moves into the open, lower side of hook 179 by passing along beveled edge
187.
The inner, open area of hook 179 is larger than the diameter of post 181 so
that post
181 has adequate clearance to drop out of hook 179 and away from transfer link
169
when cover 13 is opened, and to return into hook 179 as cover 13 is closed.
The
rearward inside of hook 179 includes a recessed portion forming a seat 193 for
receiving post 181 and returning it with transfer bar 147 to its set position.
[106] The transfer mechanism also preferably includes a return mechanism for
returning
transfer bar 147 to its set position. In a preferred embodiment, this
mechanism
comprises a spring retaining member 195 which secures a first end of a coil
spring
197, or other type of resilient return member, to transfer gear 165. The
second end of
coil spring 197 is suitably secured to left chassis member 7 or another part
of
dispenser 1. When transfer bar 147 is in its set position, coil spring 197 is
relaxed or
just lightly tensioned. When transfer gear 165 rotates in response to
operation of
transfer motor 151 and rotation of gear 163, coil spring 197 is extended,
transfer link
169 is caused to move toward the rear of the dispenser and transfer bar 147
rotates in
the direction of nip 37. After transfer gear 165 has rotated to its limit
(thus causing a
leading edge portion of web 18 to be transferred into nip 37), transfer motor
151 is
deactivated. The output shaft of deactivated transfer motor 151 free-wheels in
its
reverse direction, allowing spring 197 to return to its rest state while
returning transfer
gear 165 to its set position (the same position it was in before transfer
motor 151 was
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activated). During the return strolce, seat 193 engages post 181 and returns
it and
transfer bar 147 to their set positions. Instead of a spring-biased return
mechanism,
the motor control circuitry could provide a reverse drive of transfer motor
151 serving
to drive transfer bar 147, transfer link 169 and transfer gear 165 to their
set positions
after web 18 has been introduced and fed through nip 37.
(107] To load a roll in dispenser 1, or to transfer a partially depleted roll
from upper
supports 21, 27 to lower supports 29, 31, an attendant unlocks or unlatches
dispenser
cover 13 and rotates it downwardly to the web loading position shown in Fig.
1. In its
open position, the front panel of cover 13 will no longer abut against
transfer bar 147
and support it in its set position. As a result, transfer bar 147 will fall
out of hook
179. Transfer bar 147 pivots downwaxdly away from nip 37 about stub shafts 161
as
has been described. Both cover 13 and transfer bar 147 assume respective web
loading positions where they will not interfere with an attendant installing a
roll in the
dispenser l and positioning a leading edge portion of web 18 for transfer into
feed nip
37.
[108] In a preferred embodiment, upon loading a reserve roll into upper pair
of supports 21,
27, the attendant will position the leading edge portion of web 18 in cradle
107
located in front of, and below, feed nip 37. After positioning web 18 in
cradle 107,
the attendant will close cover 13 by rotating it upward toward the chassis
assembly
and back panel member 11. As the cover is rotated upwardly, an inner front
surface
of cover 13 contacts cover engaging members 159 on transfer bar 147 and
rotates
transfer bar 147 to its set position, as has been described. As cover 13 is
being closed
and transfer bar 14 is rotated to its set position, post 181 is pivoted
upwardly into
hoolc 179.
[109] As cover 13 is closed, cover switch 109 (see Figs. 1 and 20) is engaged
to activate
feed roller drive motor 49, to advance any sheet material present in the feed
mechanism. Concurrently, sensors 11 l, 113 detect the presence or absence of
web 18
in discharge chute 12. When an absence of web continues to be detected by
sensors
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111, 113 for a predetermined advancement interval, the feed transfer mechanism
is
actuated, as feed roller 33 continues to be driven. With reference again to
Fig. 15,
transfer motor 151 drives output gear 163 in a counter-cloclcwise direction,
which in
turn drives transfer gear 165 in a clockwise direction. This results in
transfer link 169
moving rearwardly. As transfer link 169 moves rearwardly, hook 179 engages
post
181 and imparts the movement of link 169 thereto. As post 181 is pulled
rearwardly,
transfer bar 147 pivots toward feed nip 37 about stub shafts 161. Fingers 153
engage
the leading portion of web 18 hanging in front of nip 37. Fingers 153 rotate
until they
abut against, or reside in close proximity to, feed roller 33 and/or pressure
roller 35.
As this occurs, web 18 is introduced into nip 37 and talcen up by the feed
mechanism,
and transfer motor 151 is deactivated. Once motor 151 stops, return spring 197
(or
another return mechanism) causes transfer link 169 and transfer bar 147 to
return to
their set positions.
[110] After a transfer of feed to a reserve roll rotatably supported between
upper supports
22, 27, dispensing from that roll (now the working roll) may continue until
the web
sensing system detects that that roll has been fully depleted. (As previously
described, a sensor may, in the interim, signal a partial depletion condition
permitting
transfer of the roll from upper supports 21, 27 to lower supports 29, 31.)
When
depletion of the working roll is sensed, e.g., by the continued absence of web
material
at the sensing position following advancement of the feed roller a
predetermined
amount, the transfer mechanism is activated for introduction of a leading
portion of
the reserve roll material into the feed nip. This introduction is accomplished
in the
manner discussed previously with respect to the introduction and feeding of an
initial
roll loaded into the dispenser following closure of cover 13. In carrying out
an
automatic feed transfer, fingers 153 position the reserve web in nip 37
without cover
13 being opened, so that the reserve web is introduced into, and picked up by,
the feed
mechanism immediately following depletion of the prior roll. The feed transfer
operation may thus be carried out in a manner that is substantially
transparent to the
user.
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Electrically Actuated Release Of Spring Biased Transfer Bar
[111] An alternative arrangement for effecting a transfer of feed to a new or
reserve roll is
now described with reference to Figs. 16A-16E. In this embodiment, an
electrically
actuated device, e.g., a motor 199, is utilized to actuate release of a
transfer bar 200,
which is biased toward feed nip 371 by a spring 201, or the like.
[112] Referring to Fig. 16A, a dispenser 1' is shown in a condition where web
material 203
has been fed from a stub roll 204 through a feed mechmism formed by a feed
roller
33', a pinch roller 3S', a middle chassis member 9' and a face plate structure
43'. A
reserve roll mounted in an upper pair of supports (not shown) has a leading
portion of
sheet material 18' hanging down in front of a feed nip 37'. Pivotally mounted
transfer
bar 200 is spring loaded rearwardly by spring 201, which is braced against an
inside
front surface of closed cover 13'. Transfer bar 200 is held in a set position
by a
pivotally mounted transfer Iink 205. Transfer link 20S is biased to its most
counter-
clockwise position by a tension spring 207. The pivotal motion of transfer
link 20S is
limited in both directions by pins 209, 211. When the web 203 from stub roll
207 is
completely depleted, the dispenser control system senses this (in a manner as
has been
described), and power is applied to transfer motor 199.
(113] Referring to Fig. 16B, dispenser 1' is shown after stub roll 204 has
been completely
depleted and transfer motor 199 has been activated to rotate transfer linl~
20S
clockwise, overcoming the pull of spring 207. This rotation of transfer link
20S frees
transfer bar 200 to rotate counter-clockwise under the bias of spring 201,
pushing the
leading portion of web 1 ~' into feed nip 37'.
[114] In Fig. 16C, dispenser 1' is shown just after a feed transfer has been
completed. The
leading sheet segment has been fed through nip 37' and has emerged from
discharge
chute 41' and outlet 4S' in a folded-over state. Transfer motor 199 is turned
off once
transfer linlc 20S has been pivoted to its limit. This can be effected by
having the
dispenser electronics detect a stall condition as transfer link 20S bottoms on
travel
limiting pin 209. Once motor 199 is switched off, transfer link 207 is
permitted to
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relax into its counter-clockwise position against pin 21 l, under the bias of
spring 207.
In place of motor 199, an electric solenoid or the like may be suitably
arranged to
move transfer link 205 to its transfer bar setting and/or release positions.
[115] Referring now to Fig. 16D, dispenser 1' is shown with dispenser cover
13' open so
that it may be refilled. Having cover 13' open allows transfer bar 200 to fall
open
(pivot forwardly) by virtue of its over-center position. Empty stub roll core
204 has
been released to fall through a gap 213 formed between middle chassis member
9'
and back panel member 11' into cover 13' where it can be easily removed by the
attendant. The roll of paper held in the upper supports (not shown), from
which web
18' extends, has been depleted to the point that it may be transferred from
the upper
pair of supports to the lower position, as illustrated in Fig. 16E, while web
18'
remains fed through the feed mechanism.
[116] Fig. 16E shows dispenser 1' in a reload condition. Working roll 17' has
been moved
to the lower stub roll position while web 18' remains fed through the feed
mechanism.
A new full roll (not shown) has been placed in the upper supports and a
leading
segment 18" drapes down over feed nip 37'. The web can be placed in a clip or
cradle, as has been described, or transfer bar 200 itself may serve to hold
the web.
Upon closing cover 13', transfer bar spring 201 is loaded and dispenser 1'
assumes
once again the condition shown in Fig. 16A.
Roll Core Removal
[lI7] Referring now to Figs. l, 4, 9, 17 and 18, a system permitting highly
efficient removal
of spent stub rolls (roll cores) from dispenser 1 is described. Lower roll
support 29
connected to right side chassis member 5, together with opposing support hub
31
connected to left side chassis member 7, provide a releasable rotatable mount
for a
web material roll transferred down from upper supports 21, 27. So mounted, a
transferred "stub" roll, from which material may continue to be fed, is
positioned in
alignment with an elongated, generally rectangular gap 215 (see Fig. 17)
defined
between dispenser back panel member 11 and middle chassis member 9. Support 29
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is made movable by finger operation between a core retention position and a
core
release position. Displacement of support 29 to its release position moves a
mounting
hub 217 thereof away from opposing (fixed) support hub 31, thereby increasing
the
distance between the opposed roll core hubs to the point where the core 219
(see Fig.
18) is no longer supported. Upon support 29 being moved to its'release
position,
retained core 219 is thus released to fall directly through gap 215. In its
open
position, e.g., as seen in Fig. 9, dispenser cover 13 is positioned to receive
roll core
219 dropped through gap 215, and to place it where a custodian can easily
remove it.
[118) As seen clearly in Fig. 18, releasable support 29 includes a spring arm
221, a forger
graspable release handle 223, and roll core mounting hub 217. At its upper end
225,
spring arm 221 is cantilever mounted to an inner side of a wall 225 of right
side
chassis member 5. In its rest position, a major lower portion of spring arm
221 is
angled inwardly with respect to the inner side 225, toward roll core 219.
Release
handle 223 and mounting hub 217 are each disposed adjacent the lower end of
spring
arm 221, protruding laterally from opposite sides thereof.
[119) Release handle 223 is provided in the form of a slightly curved tab with
a built-up
outer edge 227. Handle 223 extends through a passage 229 formed in wall 225
such
that it is readily graspable by an attendant from the outside of right side
chassis
member 5, once cover 13 is opened.
[120) A catch arm 231 is also preferably attached to the lower end of spring
arm 221. Catch
arm 231 extends laterally from spring arm 221, below release handle 223,
through a
passage 232 provided chassis wall 225. Catch arm 231 has a downwardly directed
catch member 233 proximate its outer end 235. Catch member 233 and passage 229
are sized and configured such that catch member 233 abuts with an outside
surface of
chassis wall 225 to limit the inward deflection of spring arm 221 when no roll
core
219 is present. As such, catch member 233 serves to maintain spring arm 221 in
a set
position, facilitating roll insertion by mere dropping of the roll in between
support
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hubs 217, 31; the need for separate manual retraction of roll support 29 using
release
handle 223 is not required to load a roll.
[121] Cover 13 is pivotally mounted at its lower rear corner to back panel
member 11, and
opens by rotating away from the chassis assembly to the open position shown,
e.g., in
Fig. 9. In the open position, a cavity 235 formed by the cover front panel and
sidewalls extends below gap 215 to catch a core 219 released from lower
supports 29,
31 and dropped through gap 215. As best seen in Fig. 9, in the open position,
the
cover front panel forms a cavity floor 237 which is inclined slightly
forwardly. This
incline serves to encourage a core dropped thereon to roll, under
gravitational force,
into a forward portion of the open cover, where it may be readily removed by
an
attendant.
Proximity Sensing System
[122] Referring to Fig. 20, dispenser 1 preferably includes, as a sheet
request switch/sensor
237, a proximity sensing system for detecting the presence of a user's hands
or the like
as they approach the front of dispenser 1. As generally described in
application Serial
No. 09/081,637, the sensor may be of any suitable type, and preferably is a
non-
contact sensor such as a capacitive or IR sensor. In the illustrated preferred
embodiment, a proximity sensor antenna plate 239 (see, e.g., Figs. 11-12) is
driven by
an oscillator circuit. The oscillator circuit is coupled with microprocessor
115, which
detects the presence of a user's hand based upon a voltage related to the
amplitude of
the oscillations. Microprocessor 115 activates motor 49 when a hand is
detected, so
as to drive feed roller 33 and thereby dispense a length of the material.
[123] As best seen in Figs. 11-12, antenna plate 239 rnay be formed as a
metalized front-
facing surface of an elongated printed circuit board (PCB) 241 that may be
clipped
into place on faceplate structure 43, in overlying relation with PCB 123. This
may be
accomplished with a deflectable spring ann 243 located on faceplate structure
43, to
the right side of recess 125, amd a pair of shoulder-forming bosses 245, 247
positioned
one above the other at a left side of recess 125.
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[I24] Figure 19 shows a schematic diagram of a preferred embodiment of a
proximity
sensing system 249 that is used for sensing the proximity of user's hand as
the user's
hand approaches the front of the dispenser 10. Proximity sensing system 249
includes
an oscillator circuit 251 and an automatic sensitivity control circuit 253.
Oscillator
circuit 251 includes an inductor LI, capacitors C15, C16 and C17, npn
transistors Q16
and Q14, and resistors R35 and R17 that are connected in a Colpitts oscillator-
type
topology, that is, having a split capacitor configuration (capacitors C16 and
C17).
Automatic sensitivity control circuit 253 includes transistors Q12, QS and
Q15.
[125] In oscillator circuit 251, the base of transistor Q16 is connected to
one terminal of
inductor Ll and to one terminal of capacitor C17. The other terminal of
capacitor
C17 is connected to one terminal of capacitor C16. The other terminal of
capacitor
C16 is connected to the remaining terminal of inductor LI. Antenna plate 239
is
connected to the base of transistor Q16 at the point in the resonant circuit
formed by
inductor L1 and capacitors C16 and G17 that is normally connected to ground. A
shield 255 is physically positioned between antenna plate 239 and optical
sensors 115,
117, and is connected to the junction of capacitors C16 and C17. The collector
of
transistor Q I4 is connected to the emitter of transistor Q 16 and to the
junction of
capacitors C16 and C17. The base of transistor Q14 is connected to the emitter
of
transistor Q16 through resistor R3S, and to ground through capacitor CIS. The
emitter of transistor Q 14 is connected to an automatic sensitivity control
circuit
formed by transistors Q12, Q5 and Q1S, and which will be described below.
[126] As shown in Figure 19, transistors Q16 and QI4 are each preferably
MMBT3904 npn
transistors. Preferably, inductor Ll is a 330 p.H inductor, capacitor C16 is a
1500 pF
capacitor, capacitor C17 is an 1800 pF capacitor, and capacitor C15 is an 0.01
p.F
capacitor. Preferably, resistor R35 is a 100 kS2 resistor. The collector of
transistor
Q16 is connected to a suitable power supply voltage, such as +5 Vdc, and the
base of
transistor Q16 is connected to a drive voltage signal PROX EN that is output
from
microprocessor 115 through resistor R37. Resistor R37 is preferably 332 kS2.
Test
point T6 is connected to signal PROX EN for convenience in troubleshooting.
When
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drive voltage signal PROX_EN is low, oscillator circuit 251 is disabled. When
drive
voltage signal PROX EN is high, oscillator circuit 251 is enabled.
[127] Transistor Q16 is the active element of oscillator circuit 2000, and
transistor Q14 is an
active load for transistor Q16. Transistor Q14 allows the necessary current to
flow
through transistor Q16, while not loading down the output of transistor Q16.
Transistor Q14 also stabilizes the amplitude of the oscillator output by
adjusting the
current through transistor Q16. In the absence of oscillation, transistor Q14
is biased
fully on by resistor R35, allowing maximum current to flow through transistor
Q16.
Transistor Q16 receives base drive through resistor R37. The transistor noise
that
starts oscillation is coupled to ground through antenna plate 239. There is
always
sufficient stray capacitance through the sensor field to antenna plate 239 for
oscillation to occur, even when no hand is in the sensing field of antenna
plate 239.
[128] In the illustrated preferred arrangement of antenna plate 239 and
optical sensors 115,
117, the optical sensors contribute a stray capacitance that is approximately
two
orders of magnitude greater that the stray capacitance of a hand. That is, the
stray
capacitance between antennal plate 239 and optical sensors is about 100 pF and
the
stray capacitance of a hand is about 1 pF. Ita. the illustrated preferred
arrangement of
the invention, oscillator circuit 249 drives shield 255 (see Figs. 12 and 19),
which is
fomned as a metalized layer on a back-side of PCB 241 (which has antenna plate
239
formed on its front surface). This reduces the baseline stray capacitance of
antenna
plate 239, and minimizes the stray capacitance to antenna plate 239 caused by
optical
sensors 115, 117, thereby improving sensitivity for detecting the presence of
a hand
near antenna plate 239.
[129] As depicted in Fig. 22, a relatively large ground plate 257 is
preferably mounted on
the bottom surface of middle chassis member 9. Ground plate 257 may be
provided,
e.g., in the form of an adhesively applied metal foil/plastic laminate. Ground
plate
257 serves to direct downwardly and render more predictable the sensing field
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generated by the oscillation applied to antenna plate 239, as the signal
naturally seeks
the most direct path to ground.
[130] Once oscillation begins, the base-to-collector junction of transistor
Q14 becomes
forward biased, draining some charge off capacitor C15, and causing transistor
Q14 to
reduce the current drawn through transistor Q 16 in order to maintain a fixed
oscillation amplitude. The positive peak of oscillation at the emitter of
transistor Q16
is approximately Vcc (+5 Vdc), while the negative peak is approximately the
voltage
on capacitor C15 minus about 0.6 V. The voltage on capacitor C15 is held
constant
because the emitter voltage of transistor Q14 is held constant by the
automatic
sensitivity control circuit formed by transistors Q12, QS and Q15.
[131] When a hand is placed near antenna plate 239, the stray capacitance of
antenna plate
239 increases from a baseline stray capacitance of antenna plate 239 caused
the
dispenser components and the ambient environment in which dispenser is
positioned.
As the stray capacitance increases, the path that the sensing field must
travel in order
to return to ground is shortened, and the oscillator tries to oscillate at an
increased
amplitude. The increased oscillation amplitude drains off additional charge
from
capacitor C15, reducing the current through transistor Q16, and thereby
counteracting
the increased amplitude of oscillation. The change in current is sensed across
resistors R33 and R36 and is amplified by Q12 and QS to a usable level and
sent to an
analog input of microprocessor 115 as a V PROX_OUT signal, where it is used to
trigger a dispensing operation. The sudden drop in voltage at the collector of
QS is
interference filtered and detected by firmware and, if considered a valid
trigger event,
starts the dispenser. Test point T1 is connected to signal V_PROX OUT for
convenience in troubleshooting.
[132] Automatic sensitivity control circuit 253 includes transistors Q12, Q5,
Q15 and Q6,
resistors R18, R21, R22, R25, R26, R31, R33 and R36, diode D8 and capacitors
C10
and C12. The base of transistor Q12 is connected to the emitter of transistor
Q14.
The collector of transistor Q12 is connected to the power supply voltage
through
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resistor R21 and to the base of transistor Q5. The emitter of transistor QS is
connected to the power supply voltage, and the collector of transistor QS is
connected
to the emitter of transistor Q12 through resistor R25, to the anode of diode
D8, and to
one terminal of capacitor C10. The cathode of diode D8 is connected to the
gate of
transistor Q15 and to one terminal of capacitor C12. The drain of transistor
Q15 is
connected to the emitter of transistor Q14 through resistor R33 and to ground
through
resistor R36. The collector of transistor Q6 is connected to the gate of
transistor Q16
through resistor R 22. The emitter of transistor Q6 is connected to ground,
and the
base of transistor Q6 _is connected to a PROX SH signal that is output from
microprocessor 115.
[l33] As shown in Figure 19, transistors Q12 and Q6 are each preferably
MMBT3905 npn
transistors, transistor QS is preferably an MMBT3906 pnp transistor,
transistor Q15 is
preferably an MMBF170 MOSFET. Preferably, the resistance values of resistor
R18
is 221 kSZ, R21 is 100 kS~,, resistor R22 is 475 kSZ, resistor R25 is 22.1
kSZ, resistor
R26 is 100 S~, resistor R31 is 499 S~, resistor R33 is 332 SZ and resistor R36
is
4.75 kS~. Preferably, diode D8 is a DL4148 diode, and preferably capacitor C10
is an
0.01 ~.F capacitor. Capacitor C12 is preferably a 10 ~,F capacitor.
[134] The automatic sensitivity control circuitry formed by transistors Q12,
QS and Q15
compensates for the reduction in sensitivity for sensing a hand when more
stray
capacitance is added to the dispenser's sense environment, that is, when the
baseline
stray capacitance of antenna plate 239 is relatively large because, e.g., a
large metal
object is located near antenna plate 239. The reduction in sensitivity for
sensing a
hand in an environment providing a relatively larger baseline stray
capacitance is due
to the fact that the change in capacitance due to a hand in the sensing field
is a
relatively smaller percentage of the overall capacitance sensed by antenna
plate 239.
[135] In operation, the automatic sensitivity control circuitry maintains
approximately 3 V
at the collector of transistor QS and approximately 0.6 V at the emitter of
transistor
Q14. When, e.g., a large metal object is brought near dispenser 10, transistor
Q14
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will reduce the current flow through transistor Q16, thereby correcting an
increase in
the oscillation amplitude caused by the increased stray capacitance sensed by
antenna
plate 239. The reduction in current through transistor QI6 lowers the voltage
on the
emitter of transistor QI4. The voltage at the collector of transistor QS
begins to
decrease due to the gain of transistors Q12 and QS (as set by resistors R31
and R25).
As a result, capacitor C 12 discharges through its own leakage or through
resistor R22
(depending on firmware mode) and causes transistor Q15 to conduct less.
Because
transistor Q15 is a MOSFET, the resistance of transistor QIS increases,
thereby
increasing the resistance between the emitter of transistor Q14 and ground and
effectively increasing the proximity detection circuit gain, while lowering
the
oscillator current by an corresponding amount. Resistors R33 and R36 limit the
adjustment range of the control loop in order to keep the automatic
sensitivity control
loop stable. Transistor Q6 and resistor R22 function as an AGC pull-down
circuit for
speeding recalibration of proximity sensor circuit 251 under control of
microprocessor
115 through the PROX_SH signal. Test point T14 is connected to signal PRO SH
for convenience in troubleshooting.
[136] When a hand is removed from the sensing field, readjustment of the
control loop for
maximum sensitivity occurs rapidly due to diode D8. Reduction of proximity
sensitivity, such as when a hand is in the sensing field, is much slower and
is
determined by the leakage in capacitor C12 and whether transistor Q6 is turned
on.
[137] While proximity sensor system 249 has been described in the context of
sheet
material dispenser I, it should be understood that the proximity sensor system
of the
present invention can be used in virtually any application where it is desired
to detect
the presence or proximity of a user, or other object, relative to something
else. This
includes (but is not limited to) various types of hands-free or automatic
dispenser
devices, such as water faucets or fountains, soap dispensers and drink
dispensers.
Additional Electrical System/Control Aspects
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[138] The various electrical component's of dispenser 1, and their
interrelationship with each
other, are shown in the block diagram of Fig. 20. In addition to receiving
input
signals from proximity sensing system 249, optical sensors 111, 113, sheet
displacement detector (encoder) 135, and cover switch 109, microprocessor 115
may
also optionally receive input fiom a manual reset button 259 effectively
serving to
return the state of microprocessor 115 to the initial state assumed upon
closure of
cover 13. In addition, microprocessor 115 may be used to pulse power on and
off to
optical sensors 111, 113, and to displacement detector 135, as an energy
saving
measure. As a further energy saving measure, program logic (e.g., a watch-dog
timer)
may be provided to place microprocessor 11 S in a sleep mode after a
predetermined
period of inactivity, and to periodically wake the system from the sleep mode.
In a
preferred embodiment, proximity sensing system 249 is powered down, and not
polled, so long as optical sensors 111, 113 indicate the presence of web
material in
discharge chute 19.
[139] Microprocessor 115 and/or associated circuitry preferably comprise a
voltage detector
for detecting a low battery condition of the dispenser and indicating the
same, e.g., by
flashing a low battery indicator LED 260 (see Figs. 1 and 20). Microprocessor
115
may also be used in conjunction with the voltage detector to provide pulse
width
modulation (PWM) control of drive motor 49 and/or transfer motor 151, in order
to
maintain a substantially constant motor speed despite fluctuations in the
output
voltage of the batteries over their lifetime. In this manner, a desirable
consistency of
dispense (and transfer) cycle times can be achieved; in addition, potential
for the
previously described feed mechanism overshoot problem can be reduced.
[140] An option switch may be provided for switching dispenser 1 to a "towel
hanging"
mode. Upon closure of cover 13, microprocessor 115 may check the option switch
and if set to the "towel hanging" mode, the proximity sensing system may be
disabled
entirely until the next system reset (such as by a subsequent cover closure,
or
actuation of reset switch 259). In this mode, optical sensors 111, 113 may be
polled
at a reduced rate (e.g., two times per second) to cause a dispensing operation
to be
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carried out upon the detection of a web absent condition. Alternatively,
optical
sensors 11 l, 113 may be powered down and not polled until after
microprocessor 115
is awakened by an interrupt generated by the proximity sensing system
detecting a
hand in close proximity to the dispenser (a sheet request). Instead of waking
microprocessor 115 by interrupt, a watch dog timer may be employed to
periodically
wake microprocessor 115 to poll the proximity sensing system, e.g., at a rate
of five
times per second.
Electrostatic Discharge Protection
[141] Operation of the electronic control circuitry of dispenser 1 may be
adversely affected
by the build-up of static electricity on feed roller 33 and/or pressure roller
35. This is
particularly so due to the proximity of the circuitry to the feed and pressure
rollers.
Advancement of paper or other insulative web materials across the rollers
ordinarily
would result in the build-up of a considerable amount of static electricity on
the
rollers, thus placing the electronic control circuitry at risk of malfunction
or damage.
[142] An approach utilized in dispenser 1 for ,avoiding electrostatic
discharge build-up on
feed roller 33 and pressure roller 35 is now described with reference to Fig.
4. In
accordance with the teachings of co-pending, commonly owned U.S. patent
application Serial No. 09/966,124, filed September 27, 2001, a conductive path
may
be formed by a wire, cable, metal strap and/or other conductor that extends
from
pressure roller 35 to a dispenser supporting structure (e.g., a mounting
Wall). The
supporting structure may act as a local ground for discharging static
electricity
generated as web material (typically, but not necessarily, paper) is passed
through
feed nip 3 7.
[143] As illustrated in Fig. 4, pressure roller 35 may include a pair of
opposing support pins
261 (one shown) protruding outwardly from its opposite ends, which seine to
rotatably mount pressure roller 35 between side chassis members 5, 7. Pins 261
are
preferably formed of metal, e.g., aluminum, or other highly conductive
material, as is
roller 35 itself. A wire, cable, metal strap, etc. may be used to establish a
conductive
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path which extends from roller pin 261 to a terminal, such as a screw or
spring
contact, that can be connected to a wall or other supporting structure upon
which
dispenser 1 is mounted. Metal pin 261 and metal pressure roller 35 complete
the
conductive path from the supporting structure (e.g., wall) serving as a local
ground, to
feed nip 37, whereby static electricity built-up on the rubber or like
insulative
gripping surface of feed roller 33 may be continuously discharged.
[144] In order to provide a reliable, uninterrupted contact between a wire 263
extending to
the rear side of back panel member 11 and rotatable pressure roller pin 261, a
metal
strap 265 forms a contact arm that is spring biased into sliding contact with
an outer
circumferential surface of pin 26. The contact ann thus remains in contact
with pin
26 as it rotates. Strap 265 is secured within right side chassis member 5 by a
pair of
guides 267. Contact arm is elastically bent around guides 267 to form a leaf
spring
serving to bias the end of the thus formed arm into reliable sliding
electrical contact
with roller pin 261. An opposite end of metal strap 265 connects with wire
263. Wire
263 is threaded along an outer perimeter of right side chassis member 5 to a
back side
of back panel member 11 where it may be connected to the dispenser support
structure (e.g., a wall), such as by a screw or spring contact.
[145] Use of elongated conductors, such as wire 263 and metal strap 265, is
just one of
many possible approaches for providing a conductive path from roller 265 to
the
dispenser support structure. In lieu of a separate wire or like discrete
elongated
conductor, the desired conductive path could be established by interconnected
metal
or other conductive structural components incorporated into or directly
forming
chassis assembly 3 and/or back panel member 11. In the event the dispenser
support
structure is highly insulative (e.g., a ceramic tile wall), it has been found
desirable to
provide an increased contact surface area, such as through use of a foil or
metal plate
placed in contact with the supporting structure.
Dispenser Operation Control Logic
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[146] Referring now to Figs. 2IA and 21B, exemplary control logic for
operation of towel
dispenser 1 is described. Control may begin with the detection of an open
cover or
towel request, at step 267. If the cover is closed and a sheet request occurs,
such as
by detection of a hand by proximity sensing system 249, control proceeds to
step 269
where it is determined if a towel segment is present in discharge chute 41
(see Fig.
12), that is, if a previously fed towel has not been torn off. If a towel is
present,
control returns to step 267; control loops between steps 267 and 269 until a
towel
absent condition is detected. Once a towel absent condition is detected in
step 269,
control proceeds to step 271 where a sheet detection timer is initialized. If
a "sheet
hanging" mode is selected, the sheet request check of step 267 is skipped.
[147] In following step 273, feed motor 49 is started in the forward feed
direction to attempt
a first interval of sheet advancement. Control then proceeds to step 275 where
a
check is made to see if a leading edge of sheet is detected. As has been
described, a
leading edge may be determined based upon a transition from a web present to a
web
absent condition, at either one of sensors 11 l, 113. Upon detection of a
leading edge,
a counter associated with sheet displacement sensor 135 is initialized, in
step 277. In
step 279, feed motor 49 continues to run for a predetermined (second) dispense
interval, whereby a leading segment of sheet material is fed out to a position
where it
may be removed by a user. This may be carried out by counting the number of
pulses
of displacement detector 135 and comparing the count accumulated (from the
initialization of step 277) with a preset count value corresponding to the
sheet
segment length. In particular, the preset count value is set such that it,
together with
the amount of sheet displacement that occurs (in step 273) prior to
initialization of the
sheet displacement detector, provides a total displacement serving to position
successive tear lines 19 within discharge chute 41, downstream of the feed
mechanism but upstream of the sensors 111, 113. As has been described, the
preset
count value may be an adjusted count value obtained by subtracting from the
desired
displacement a predicted "overshoot" of the feed mechanism once the motor is
turned
off. Although variable, the pre-initialization feed-out of sheet material
preferably
nominally equals one-half of the distance between the feed mechanism and
sensors
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111, 113, based upon a target placement of successive tear lines midway
between the
feed mechanism and sensors 111, 113.
[148] Motor operation is continued in step 279 until the cumulative count
value reaches the
preset count value. In step 81, sensors I'I1, I13 are polled to detect removal
of the
dispensed sheet segment by a user. Control loops at step 281 until removal of
the
dispensed sheet is detected. Although not illustrated, microprocessor 115 may
implement sleep modes to reduce power consumption during prolonged periods of
inactivity, as has been described. If removal of the dispensed sheet segment
is
detected, control flow returns to Start.
[149] If, in step 275, a leading edge of the sheet is not detected, the sheet
detection timer
initialized in step 271 is decremented, in step 283, and then checked to see
if it has
timed out, in step 285. So Iong as the sheet detection timer is not timed out,
control
proceeds to step 287 where a checlc for detection of a leading edge is once
again
carried out. If a leading edge is not detected, control loops back to step
283. If a
leading edge is detected, control proceeds to step 277, and thereafter in the
manner as
has been described.
[150] If, in step 285, the sheet detection timer has timed out, control
proceeds to step 289
where a first feed transfer is attempted, by actuation of the feed transfer
mechanism.
Then, in step 291, the sheet detection timer is reinitialized. Next, in step
293 (Fig.
2I B), sensors I 11,113 are once again checked to see if a leading edge of
towel has
been detected. If yes, control returns to step 277 (Fig. 21A) and thereafter
proceeds as
has been described. If not, the sheet detection timer is decremented, in step
295 and
checked to see if it has timed out, in step 297. So long as it has not,
control proceeds
to step 299 where another check is made fox detection of a leading edge. If a
leading
edge has been detected, this indicates that the first feed transfer attempt
was
successful, and control returns to step 277 (Fig. 21A). From there, control
proceeds
as has been described.
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[151] If a leading edge is not detected in step 299, control loops baclc to
sheet detection
timer decrementing step 295 and time-out detection step 297. If a leading edge
is not
detected before the sheet detection timer times out, control proceeds to step
301 where
a second transfer attempt is carried out, by actuation of the transfer
mechanism. Next,
in step 303, the sheet detection timer is reinitialized and another check for
detection of
a leading edge of towel is made, in step 305. Upon detection of a Leading
edge,
control returns to step 277 (Fig. 21A) and proceeds as has been described. If
a
leading towel edge is not detected in step 305, the sheet detection timer is
decremented in step 307 and a check is made in step 309 to see whether the
sheet
detection timer has timed out. So long as it has not, another check for a
leading edge
is made in step 311. If a leading edge is detected, control returns to step
277 (Fig.
21A) and thereafter proceeds as has been described. If not, control loops back
to step
307 and then step 309. Once it is detected, in step 309, that the sheet
detection timer
has timed out, the system assumes that the roll material within the dispenser
is
depleted, or that a malfunction has occurred. Accordingly, control proceeds to
step
313 (Fig. 21A) where feed motor 49 is stopped and LED indicator light 153 is
blinked.
[152] If a cover-open condition is detected in step 267, this indicates that
the dispenser is
being serviced, such as by an attendant replenishing the dispenser and setting
up the
web material for transfer into feed nip 37 (step 315). The program pauses at
step 317
until a cover closure is detected, whereupon control proceeds to step 271, and
thereafter as has been described.
(153] In the above exemplary control embodiment, upon closure of cover 13 the
dispenser
waits for a sheet request signal before dispensing a sheet segment.
Alternatively, a
sheet segment is immediately dispensed upon the cover being closed (whether or
not
the "sheet hanging" mode is selected). With reference to Fig. 23, an advantage
of this
system will now be described. If cover 13 of dispenser 1 is opened while a
leading
sheet segment extends out of the discharge opening, when the cover is again
closed a
leading portion 319 the leading segment may become lodged between the inside
of
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cover 13 and the bottom side of middle chassis member 9. When this happens,
the
leading segment may not protrude from the discharge opening sufficiently to be
easily
grabbed by a user or attendant. By automatically carrying out a dispense
operation
upon cover closure (notwithstanding that web sensors 111, 113 detect the
presence of
sheet material), a sufficient amount of sheet material will be advanced out of
the
dispenser to form a sheet material loop 321 that may readily grasped and
pulled-on to
free lodged leading portion 319. In addition, an attendant receives immediate
feedback indicating that the roll material is properly loaded and the
dispenser is
operating properly.
[154] Relatedly, the dispense amount of an initial dispense operation
following a feed
transfer operation is preferably adjusted (decreased) to compensate for the
effective
shortening of the leading segment resulting from transfer bar 147 (or 200)
pressing
the leading portion of web 18 into nip 37 (see, e.g:, Figs. 15 and 16B). As
seen
clearly in Fig. 16C, this action typically will form a folded-over edge
portion 323
which is carried around the feed roller and into the discharge chute (41 or
41'). As a
result, web sensors 111, 113 will detect the fold-line 325 of folded-over edge
portion
323 as the free leading edge segment, and will trigger (at that point) the
second
predetermined interval of advancement, to dispense the leading sheet segment
and
properly place the adjacent tear line in the discharge chute (41 or 41'),
upstream of
sensors 111, 113 and downstream of the feed mechanism. Since the first segment
is
effectively shortened by the fold-over amount, e.g., 1 inch, the predetermined
second
interval of advancement is preferably commensurately shortened for this
initial cycle,
so as to assure proper placement of the adjacent tear line in the discharge
chute.
[155] In the above-described control embodiments, a routine may be included to
prevent
more than a predefined number of sheets from being dispensed within a
specified time
interval. If more than this predefined number of requests is made, the
controller may
be programmed to ignore the request until the lapse of a timer. So, for
example, if
more than three requests are made in a ten second period, the processor can
wait until
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the expiration of the ten second interval or for the expiration of a new ten
second
interval after the third request. This provides an additional dispenser abuse
deterrent.
(156] The present inventions have been described in terms of preferred and
exemplary
embodiments thereof. Numerous other embodiments, modifications and variations
within the scope and spirit of the appended claims will occur to persons of
ordinary
skill in the art from a review of this disclosure.
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