Note: Descriptions are shown in the official language in which they were submitted.
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Hybrid Towel Dispenser
Field of the Invention
[0001] This invention relates generally to towel dispensers and particularly
to away-from-home type paper towel dispensers.
Background of the Invention
[0002] Different types of single-use paper towel dispensers are available
for the away-from-home market. For example, folded paper towel dispensers
contain a stack of folded individual paper towel segments that are dispensed
through a slot. Other dispensers dispense paper towel segments from a tightly
wound paper roll. Such dispensers can dispense paper towel segments from
perforated or continuous paper rolls. Perforated roll dispensers contain a
continuous paper roll with longitudinally-spaced, transversely-extending
perforations that define individual paper towel segments. In continuous roll
dispensers, a continuous paper roll is cut into individual segments by a
cutting
device located in the dispenser.
[0003] There are continuous roll dispensers which require a user to
manually sever a paper segment from the continuous roll by pulling the paper
against a serrated cutting blade. Such dispensers cannot control the length of
the paper segment dispensed, and are thus susceptible to paper wastage.
Another type of continuous roll dispenser is known as a portion control
dispenser,
which automatically cuts the paper roll into paper towel segments as the paper
is
being dispensed from the dispenser. In one type of portion control dispenser,
the
paper roll is rotatably mounted inside the dispenser and a leading edge of the
paper is fed through a cutting roller and out of the dispenser through a slot.
The
paper is advanced manually by a user operating a paper advance mechanism or
pulling on the leading edge of the paper roll. When the paper advances through
the dispenser, the cutting roller rotates and a knife in the cutting roller
extends
radially outwards and punctures the paper, thereby severing a paper towel
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segment from the roll. The dispenser is designed to cut the paper into
segments
of defined length and only one at a time, thereby reducing paper wastage.
[0004] The continuous roll dispenser can be a "hands-free" (touchless)
type, i.e. designed to dispense paper towel segments without requiring the
user
to touch any part of the dispenser other than the leading edge of the paper
roll.
Such a design is particularly desirable as the user is not exposed to germs or
contaminants on other parts of the dispenser.
[0005] Hands-free dispensers can be manually operated or motorized.
Motorized hands-free dispensers typically have a proximity or motion sensor
that
detects a user's hand or hand movement. When the sensor detects a user, a
motor inside the dispenser is activated. The motor is coupled to the paper
roll
and advances a paper segment out of the dispenser. Examples of such
motorized hands-free dispensers are disclosed in US Pat nos. 5,772,291,
6,412,679, 6,695,246, 6,892,620, and 6,903,654. All of the dispensers
disclosed
in these patents require the user to manually sever a segment from the paper
roll
by applying the paper surface against a cutting knife, or as in the case of
patent
no, 6,412,679, tear a segment from a perforated paper towel roll. In other
words,
there are no known paper towel dispensers that automatically advance and cut
paper towel segments.
[0006] One problem with known motorized paper towel dispensers is that
such dispensers are rendered inoperable when the motor fails or when the
batteries die. Also, such dispensers do not allow the user to withdraw paper
from
the dispenser at a rate faster than the rate at which the paper is being
automatically advanced. Impatient users may become frustrated while waiting
for the paper to be dispensed, or worse, may damage the dispenser by pulling
on
the paper towel as it is being dispensed. Therefore, it would be desirable to
provide an automated hands-free towel dispenser that solves at least some of
these problems.
Summary of the Invention
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[0007] It is a general objective of the invention to provide an automated
hands-free towel dispenser that solves at least some of the problems in
present
towel dispensers. A particular objective of the invention is to provide an
improved hands-free towel dispenser that can automatically advance and cut a
paper towel segment for the user. A further objective of the invention is to
provide a paper towel dispenser that can operate in both an automated
dispensing mode and a manual dispensing mode.
[0008] According to one aspect of the invention, there is provided a towel
dispenser comprising: a rotatable drum having a retractable knife that extends
out of the drum when the drum rotates past a selected position; a motor
coupled
to the drum and operable to rotate the drum; and a paper guide that guides a
towel sheet onto the drum such that rotation of the drum past the selected
position advances a portion of the towel sheet out of the dispenser and severs
the portion from the towel sheet. This dispenser is thus particularly useful
for
automatically dispensing a towel sheet portion to the user without the user
having
to manually tear the portion from the towel sheet. The towel dispenser can
further comprise a sensor for detecting a user, a controller communicative
with
the sensor and motor and programmed to activate the motor when the sensor
detects a user and automatically dispense the towel sheet portion.
(0009] The dispenser can further comprise a one-way coupling which
couples the motor to the drum in a first direction (drive direction) and
decouples
the motor in an opposite second direction, thereby enabling the motor to
rotate
the drum in an automatic dispensing mode and a user to rotate the drum in a
manual dispensing mode. Example of such couplings include one-way bearings,
one-way clutches, and floating ratchets. Such a dispenser is particularly
useful
when power is unavailable to the motor, as the user can still operate the
dispenser in the manual dispensing mode. The user can rotate the drum in a
hands-on manual dispensing mode by engaging a manual advance assembly
that is rotationally coupled to the cutting drum. The manual advance assembly
can comprise a push bar or a rotary dial coupled to the cutting drum; the user
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pushes the push bar or rotates the dial to manually rotate the cutting drum
and
operate the manual advance assembly. Therefore, even if the manual advance
assembly is used (push bar or dial) or the user manually pulls the sheet from
the
dispenser, the cutting drum will rotate and knife will extend to produce a cut
sheet portion.
[0010] The drum can further comprise a cam assembly coupling the knife
to the drum such that rotation of the drum from the start position to the
selected
position extends the knife out of the drum. The drum can further comprise a
spring that is unloaded when the drum is in a start position and loaded when
the
drum is in the selected position. The spring stores suffrcient energy when
loaded
to rotate the drum from the selected position back to the start position; in
this
sense, the selected position is the drum's top dead centre position. The
dispenser can further comprise a motor-off switch that is communicative with
the
controller. The controller is programmed to stop the motor when the motor-off
switch detects the drum passing the top dead centre position; the drum returns
back to the start position by the release of spring energy.
[0011] A DC power supply can be electrically coupled to the motor. This
power supply can include at least one battery. Or, the power supply can
comprise an electrical connector for connecting to an external AC power
outlet,
and an inverter electrically coupled to the electrical connector and to the
motor.
[0012] According to another aspect of the invention, there is provided a
towel dispenser comprising: a rotatable roller drum; a motor coupled to the
roller
drum and operable to rotate the drum; a paper guide that guides a towel sheet
onto the roller drum such that rotation of the roller drum advances a portion
of the
towel sheet out of the dispenser; and, a one-way rotational coupling which
couples the motor to the drum in a first direction and decouples the motor
from
the drum in an opposite second direction, thereby enabling the motor to rotate
the drum in an automatic dispensing mode and a user to rotate the drum in a
manual dispensing mode.
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Brief Description of the Drawings
[0013] Figure 1 is a perspective view of a hands-free paper towel
dispenser according to one embodiment of the invention.
[0014] Figure 2 is a perspective view of the dispenser with its front housing
opened.
(0015] Figure 3 is a perspective, partially disassembled view of the
dispenser, illustrating the front and back housings and internal components in
assembled form.
[0016] Figure 4 is a perspective, partially disassembled view of some of
the internal components of the dispenser.
(0017] Figure 5 is a perspective partially disassembled view of a cutting
drum assembly of the dispenser.
[0018] Figures 6(a) and (b) are transparent side views of the dispenser,
with the cutting drum in a starting position (Figure 6(a)), and in a cutting
position
(Figure 6(b).
[0019] Figure 7 is a perspective partial view of the cutting drum assembly.
(0020] Figure 8 is a schematic front elevation view of parts of the paper
guide and cutting drum assembly, wherein the cutting knife is fully deployed
from
the drum assembly.
[0021] Figure 9 is a perspective partially disassembled view of the
dispenser, illustrating a motor rotatably coupled to the cutting drum
assembly.
[0022] Figure 10 is a perspective partially disassembled view of the
dispenser showing parts of the motor in exploded view.
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[0023] Figure 11 is a perspective view of the dispenser illustrating the
motor and a battery pack.
[0024] Figure 12 is a schematic diagram of automatic dispensing
components of the dispenser.
[0025] Figure 13 is a perspective view of a hands-free paper towel
dispenser according to a second embodiment of the invention.
[0026] Figure 14 is a perspective view of the dispenser shown in Figure 13
with its front housing opened.
[0027] Figure 15 is a perspective, partially disassembled view of the
dispenser shown in Figure 13, illustrating a back housing and internal
components in assembled form.
(0028] Figures 16-18 are perspective, partially disassembled views of the
dispenser shown in Figure 13, illustrating some of the internal components of
the
dispenser.
Detailed Description of Embodiments of the Invention
[0029] Directional terms such as "top", "bottom", "right", and "left" are used
in this description merely to aid in describing the embodiments of the
invention
and are not to be construed as limiting the embodiments to any particular
orientation during operation or in connection to another apparatus.
[0030] According to one embodiment of the invention and referring to
Figure 1, a hands-free paper towel dispenser 10 is provided for dispensing
paper
towel segments. The dispenser 10 can operate in an automatic hands-free mode
wherein the dispenser 10 detects the presence of a user and automatically
dispenses a paper towel segment. The dispenser 10 can also operate in a
manual hands-free mode wherein the user can, by pulling on the leading edge of
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a paper towel segment, cause the dispenser to dispense the paper towel
segment. Further, the dispenser can also operate in a manual hands-on mode
wherein the user can cause the dispenser to dispenser the paper towel segment
by operating a manual advance assembly on the dispenser. In addition, the
dispenser 10 is provided with a manual override mechanism that enables the
user to manually operate the dispenser even while the dispenser is
automatically
dispensing the paper towel segment. In this sense, the dispenser 10 is a
"hybrid
dispenser" which can operate in different manual and automatic modes.
[0031] Referring to Figures 2 and 3, the dispenser 10 has a housing
comprising a front door 12 and a rear cabinet 14; the door and cabinet 12, 14
are
hingedly interconnected, enabling the front door 12 to be swung open to
provide
access to the internal components of the dispenser 10. A locking mechanism 15
is provided to lock the door and cabinet 12, 14 together. The dispenser 10
dispenses paper towel segments cut from a paper towel roll (not shown)
rotatably
mounted on a roll holder 16 at an upper portion inside the dispenser 10. The
leading edge of a continuous sheet of paper from the paper towel roll is
threaded
through a roller assembly 18 mounted at a lower portion inside the dispenser
10
and out of the dispenser 10 through a paper slot 19 at the bottom of the
dispenser 10.
(0032] Referring to Figure 4, the roller assembly 18 comprises a number
of parts which collectively serve to feed paper from the roll holder 16 to the
slot
19, and cut the paper into uniform sized paper towel segments. In particular,
the
roller assembly 18 comprises a cutting drum 20 rotatably coupled to left and
right
side panels 22, 24. Paper threaded through the roller assembly 18 contacts
part
of the drum's surface; the cutting drum 20 operates to advance the paper
through
the roller assembly 18 and to sever power towel segments from the paper towel
roll.
(0033] Referring to both Figures 4 and 5, the cutting drum 20 comprises a
cylindrical rolling surface 21 and right and left end caps 27, 29. A drum pin
26 is
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mounted to the right end cap 27 and to the right side panel 24. A crank arm 28
is
mounted to a left end cap 29 of the cutting drum 20 and to the left side panel
22.
The crank arm 28 includes a crank bushing 30 mounted off the drum axis, and
attaches to one end of a return spring 32; the other end of the return spring
32
attaches to the left side panel 22. The return spring 32 serves to rotate the
cutting drum 20 enough to advance the leading edge of the paper roll through
the
slot 19 that the user can easily grasp the paper. Because the crank bushing 30
is mounted off the drum axis, rotation of the drum 20 (e.g. caused by the user
pulling on the paper or by a motor 60 coupled to the drum 20) loads up the
spring
32 until the spring 32 reaches a top dead centre position wherein the spring's
longitudinal axis extends through the drum centreline. That is, the spring 32
is
unloaded when the drum 20 is in a start position, and is fully loaded when the
drum 20 is in the top dead centre position. When the spring 32 passes the top-
dead centre position, the spring 32 releases its stored energy and rotates the
drum 20 through the rest of a single revolution and returns the cutting drum
20
back to the start position (as shown Figure 6(a)).
[0034] The right end cap 27 includes circumferentially-disposed teeth 33
which engage with a manual advance assembly 34. The manual advance
assembly 34 comprises a push button 35 connected at either end to left and
right
advance levers 36. The right advance lever 36 engages the teeth 33; when a
user pushes the push button 35, the lever 36 rotates the cutting drum 20 a
circumferential distance proportional to the push stroke. Such manual advance
is useful when an insufficient amount of paper extends from the slot 19 or
when
automatic dispensing operation is unavailable. Manual advance springs 38 serve
to return the advance assembly 34 back to its start position.
[0035] A knife actuator 40 extends from the right end cap 27 (off-drum
axis) and engages a cam path (not shown) located in the right side panel 24.
The knife actuator 40 is coupled to a knife holder 42, which holds a saw-tooth
cutting knife 44 having multiple teeth that extend across the width of the
knife 44.
The knife holder 42 is pivotally coupled to the rim of the right and left end
caps
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27, 29 such that the knife holder 42 and knife 44 can be pivoted between a
retracted position inside the cutting drum 20 (see Figure 6(a)), and an
extended
position wherein the knife extends radially out of the rolling surface 21
through a
knife slot 46 (see Figure 6(b)). The knife 44 is fully retracted when the
cutting
drum 20 is in the start position. Because the cutting drum 20 and knife 44 are
located inside the dispenser housing, the user is protected from the knife;
this
design is particularly safer than those dispensers that require the user to
manually sever a sheet portion from the roll by using an exposed or partially
exposed knife.
[0036] Referring now to Figures 4, 6(a) and 6(b), a front cover 48 is
mounted to the left and right side panels 22, 24 in front of the cutting drum
20.
The front cover 48 has an inside surface facing the rolling surface 21.
Fingers 49
protrude from the inside surface and terminate close to rolling surface 21;
the
fingers 49 separate the paper from the rolling surface 21 and direct the paper
downwards through the slot 19. Top and bottom pinch roller 50 are rotatably
mounted to the left and ride side panels 22, 24, and serve to guide the paper
into
and out of the roller assembly 18. A transfer mechanism 51 is pivotally
attached
to the left and right panels 22, 24 and serves to transfer paper from a stub
roll
into the roller assembly 18, in a manner well known in the art.
[0037] A paper guide 52 is mounted to the left and right side panels 22, 24
behind the cutting drum 20. The paper guide 52 comprising a plurality of ribs
54
facing the rolling surface 21, that serve to keep the paper from "bunching up"
between the paper guide 52 and rolling surface 21, and to hold the paper in
place
for cutting by the cutting knife 44. The ribs 54 are transversely spaced and
span
the width of the cutting drum 20; the spaces in between the ribs 54 are hereby
defined as "rib cavities" 55. The ribs 54 are curved and generally conform to
the
curvature of the rolling surface 21: The radial spacing between the ribs 54
and
rolling surface 21 is at a minimum at the top of the paper guide 52, which is
located at the start position of the cutting knife 44 (shown in Figure 6(a)),
and
hereby referred to as the "0 degree" position. The radial spacing widens to a
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maximum at around 135 degrees from the start position, then narrows to the
minimum at the bottom of the paper guide 52, i.e. at the finish position
around
180 degrees from the start position. This spacing between the start and finish
positions is hereby referred to as a "cutting zone" 56, and serves to provide
sufficient space for the cutting knife 44 to extend out from the cutting drum
20 but
insufficient space for the paper to bunch up. When the cutting drum 20 rotates
(clockwise in Figures 6(a) and (b)), the knife actuator 40 moves through the
cam
path, which is configured to cause the knife actuator 40 to pivot and extend
the
cutting knife 44 through the rolling surface opening 46 when the knife 44
passes
through the cutting zone 56 (as shown in Figure 6(b)), and retracts the knife
44
when the cutting drum 20 rotates out of the cutting zone 56 (as shown in
Figure
6(a)). The cutting zone 56 is shown in detail in Figure 7.
[0038] When the cutting knife 44 is fully extended and as shown in Figure
8, the knife teeth (i.e. the tips of the saw-tooth knife 44) extend between
the ribs
54 and into the rib cavities 55 in between the ribs 54, and the ribs 54 extend
into
the valleys between the knife teeth. In other words, the ribs 54 and knife
teeth
overlap in the drum's radial direction when the knife 44 is fully extended.
Note
that the radial extension of the knife 44 is less than the knife's lengthwise
extension out of the drum 20, since the knife 44 pivots out of the drum 20 at
an
angle to the drum's radial direction. This angle increases the further the
knife
pivots out of the drum 20.
[0039] When the knife 44 extends into the cutting zone 56, the knife 44
contacts the paper therein. If the knife 44 is extending with sufficient
momentum,
the knife teeth will puncture the paper upon contact, and a paper towel
segment
will be severed from the paper roll. However, if the knife does not extend
with
sufficient momentum, the knife 44 will not immediately cut the paper upon
contact, and the paper will be pushed radially against the ribs 54; as the
knife
teeth continue to extend, the teeth will puncture the paper (which is being
held
radially in place by the ribs 54) and the teeth will continue to extend into
the rib
cavities 55, severing a paper towel segment.
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[0040] The function of the ribs 54 is particularly important when the user
pulls strongly on the paper roll and causes the paper to pass quickly through
the
rolling assembly 18 - in conventional rolling assemblies, the paper tends to
become separated from the rolling surface when the paper is pulled strongly,
and
the knife often fails to completely sever the paper on the first revolution of
the
rolling drum. The knife 44 will eventually cut through the paper when the
rotation
of the drum 20 has slowed sufficiently, but uncut "double sheeted" paper towel
segments tend to be dispensed. In contrast, the ribs 54 of the dispenser 10
maintain the paper in position for cutting by the cutting knife 44 regardless
of how
strongly the user pulls the paper roll, thereby resulting in the knife 44
severing
the paper into segments in each and every rotation of the cutting drum 20.
Additionally, the rotational drag caused by the cutting action is sufficient
to slow
the rotation of the cutting drum 20 to a stop without the need of a mechanical
stopper. For typical-strength pulls on the paper roll, the drag will cause the
cutting drum 20 to stop after one full revolution. A particularly strong pull
on the
paper roll may result in the roller drum 20 rotating twice before stopping;
however, the dispenser 10 ensures that a paper towel segment will be cut and
dispensed in each revolution, thereby dispensing two paper towel segments
instead of one double-sheeted segment. This is preferable over using a
mechanical stopper, which tends to be noisy, or allowing the rolling drum and
paper roll to free-spin to a stop, which tends to cause paper to un-roll and
collect
inside the dispenser, increasing the chances of paper jamming.
[0041] Advantageously, a cut paper towel segment is provided each time
paper is dispensed using the advance lever 36. The drum 20 operates to sever a
paper towel segment from the sheet each time the drum 20 completes a
revolution; therefore, the user cannot "spool" paper using the advance
mechanism.
(0042] This embodiment features nine ribs 54 transversely spaced across
the width of the cutting roller 20; a corresponding number of knife teeth are
provided that cooperate with the rib cavities 55. A different number of ribs
and
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knife teeth can be provided within the scope of the invention so long that
there
are a sufficient number of ribs to hold the paper in place to ensure that the
paper
is cut by the knife 44. Also, the depth of the ribs 54 is selected to provide
enough
radial clearance for the rib cavities to receive the knife teeth.
[0043] Furthermore, the width of each rib can be varied within the scope of
the invention; for example, the rib width can be increased with the rib cavity
width
decreased accordingly. The knife teeth widths should also be decreased
accordingly to avoid the teeth coming into contact with the ribs.
[0044] Paper threaded through the roller assembly 18 contacts part of the
drum's surface; tension means inside the roller assembly 18 keep the paper in
sufficient tension against the drum's surface that pulling the paper through
the
roller assembly 18 will cause the cutting drum 20 to rotate. When a user pulls
the
leading edge of the paper towel roll out of the dispenser 10, the cutting drum
20
is rotated and severs a paper towel segment from the roll. Similarly, rotating
the
cutting drum 20 will cause the paper to move through the roller assembly 18.
Referring now to Figures 9 to 11, an electrical motor 60 is rotatably coupled
to
the cutting drum 20 and can be operated to rotate the cutting drum 20, thereby
advancing the paper through the roller assembly 18 and severing the paper
towel
roll into segments.
[0045] The motor 60 is a DC-powered gear head motor mounted on the
inside surface of the right side panel 24. A suitable motor is a Jameco
Reliapro
model 151440 with 4.5-12VDC operating range and a no load speed of 69 RPM;
however, other motors with similar specifications can be readily substituted.
The
motor 60 has a drive shaft 61 which extends through an opening 64 in the right
side panel 24 and connects to the inside surface of a one-way bearing 66. The
outside surface of the one-way bearing 66 is in turn coupled to a motor drive
gear
68. The motor drive gear 68 is rotatably coupled to a cutting drum drive gear
70
by an intermediate drive gear 72. The cutting drum drive gear 70 is mounted to
a shaft (not shown) coupled to the cutting drum 20 and extending along the
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rotational axis of the cutting drum 20. The drive gears 68 and 72 serve as a
reduction gears between the motor 60 and cutting drum 20.
[0046] The one-way bearing 66 is aligned to transfer torque from the motor
60 to the cutting drum 20 and yet allow the cutting drum 20 to rotate freely
in the
drive direction. Therefore, when the motor 60 is not operating, the dispenser
10
can still be operated as a manual hands-free or hands-on dispenser. In other
words, a user can pull on the leading edge of the paper towel roll, causing
the
paper to advance through the roller assembly 18 and rotate the cutting drum
20,
thereby causing the cutting drum 20 to sever a paper towel segment from the
paper towel roll. Or, the user can cause the dispenser 10 to dispense paper
towel segments by activating the manual advance assembly 34. This is
particularly useful when power is unavailable to the motor, e.g. power outage
or
dead batteries. Without such one-way bearing 66, the rotational resistance
presented by the reduction gears 68, 72 and motor 60 would make it very
difficult
to rotate the cutting drum 20. Additionally, the one-way bearing 66 allows the
cutting drum 20 to rotate at a faster rate than the rate as driven by the
motor 60.
This permits a user to manually advance the paper out of the dispenser 10 at a
faster rate than is being advanced by the motor 60.
[0047] Although the use of a one-way bearing is described here, other
one-way rotational couplings as known in the art can be substituted. Other
suitable one-way couplings include one-way clutches and one-way ratchets.
[0048] Referring to Figure 12, the motor 60 is one component of an
automatic dispensing assembly that enables the dispenser 10 to automatically
dispenser paper towel segments to the user. These components include the
motor 60, a DC power supply 80, a motor power control circuit 82, a user
sensor
84, a door open disconnect switch 86, and a motor off signal switch 88.
[0049] The DC power supply 80 is electrically coupled to the motor 60 by
the door open disconnect switch 86 and the control circuit 82. In this
embodiment, the DC power supply 80 is a battery pack comprising eight D-Cell
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batteries. Alternatively or additionally (but not shown), the DC power supply
80
can be an inverter that connects to an AC power source, e.g. a building's AC
power outlet. The inverter converts the AC power into DC for use by the motor
60. The door open disconnect switch 86 is located on the dispenser 10 such
that
the switch 86 opens when the door 12 is opened. This prevents the motor 60
from operating the cutting drum 20 and causing injury when the dispenser 10 is
being serviced.
[0050] The control circuit 82 includes a programmable logic controller
(PLC) programmed to control the automatic dispensing operation of the
dispenser 10. The control circuit 82 is electrically coupled and communicative
with the user sensor 84, the motor 60, the power supply 80 via door open
disconnect switch 86, and the motor off switch 88. The motor off switch 80 is
also
communicative with the motor 60. The sensor 84 can be any type of sensor that
detects the presence of the user, and can for example be a proximity sensor
such as an IC digital capacitance sensor, a motion sensor, or an infrared
sensor
such as a pyroelectric sensor that detects the user's body heat. The sensor 84
is
powered by the battery 80 via the control circuit 82. When the sensor 84
detects
the user, it sends a user detected signal to the control circuit 82. The PLC
of the
control circuit 82 is programmed to check the sensor 84 and when detecting the
user detected signal, to send a motor actuation signal to the motor 60. In
response to the motor actuation signal, the motor 60 activates and rotates the
cutting drum 20. When the cutting drum 20 reaches the top dead centre
position,
the motor off switch 88 is triggered and sends a stop motor signal to the
control
circuit 82; triggering the motor switch 88 at top dead centre can be
accomplished
in a variety of ways known in the art, e.g. by placing a contact on the drum
20
such that the contact triggers the switch 88 at the top dead centre position.
When the control circuit 82 receives the stop motor signal, the PLC is
programmed to stop the motor 60 by terminating the motor actuation signal. As
described above, the spring 32 is loaded when the cutting drum 20 reaches the
top dead centre position, and will release its stored energy to advance the
cutting
drum through the rest of the revolution and back to the start position. The
PLC is
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programmed to wait for a selected period of time before checking the sensor 84
again; this wait period provides the user with enough time to obtain the
dispensed towel segment and leave the vicinity of the dispenser 10.
[0051] The cutting operation performed by the cutting drum 20 through
one revolution is now described in detail, and in reference again to Figures
6(a)
and (b). The paper roll is mounted in the roll holders 16, and the leading
edge of
the paper roll is fed over the top pinch roller 50, into the space in between
the
cutting drum 20 and the paper guide 52, past the bottom pinch roller 50, and
out
of slot 19. The cutting drum 20 is in a start position wherein the cutting
knife 44
is retracted and in approximately the 0 degree position inside cutting drum
20.
When a user pulls on the leading edge of the paper roll or presses the manual
advance assembly, or the motor 60 rotates the cutting drum 20, the paper roll
will
rotate as paper is dispensed. The pinch rollers 50 keep the paper taut against
the rolling surface 21; movement of the paper causes the cutting drum 20 to
rotate, or, rotation of the drum 20 pulls paper through the roller assembly
18. As
the cutting drum 20 rotates clockwise in Figures 6(a) and 6(b), the knife
actuator
40 travels through the cam path and causes the knife holder 42 to pivot and
the
knife 44 to extend out of the rolling surface 21. When the cutting drum 21
reaches the position shown in Figure 6(b), the knife 44 is fully extended and
punctures the paper. The paper is severed, and a paper towel segment is
dispensed through the slot 19. At the position shown in Figure 6(b), the
return
spring 32 has passed top-dead-centre, and releases its energy, rotating the
cutting drum 20 back into its start position, and advancing the leading edge
of the
paper through the slot 19.
[0052] When the dispenser is dispensing paper towel segments in
automatic dispensing mode, the user can still manually operate the dispenser
in
either hands-free or hands-on manual dispensing mode. This may be desirable
when the user wishes to obtain paper at a rate that faster than the rate at
which
paper towel segments are dispensed in automatic dispensing mode. The one
way bearing enables the user to manually advance the cutting drum 20 at a
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CA 02550357 2006-06-14
faster rate than the rotational rate provided by the motor 60. When the
cutting
drum reaches top dead center position, either by the motor or by the user, the
motor off switch 88 will be triggered, and the control circuit 82 will stop
operation
of the motor 60. Similarly, the one-way bearing enables the user to rotate the
cutting drum 20 when the motor 60 is not operating.
[0053] Referring now to Figures 13-18 and according to a second
embodiment of the invention, a motorized hands-free paper towel dispenser 100
is provided that automatically advances a selected length of towel sheet from
the
dispenser. A user manually tears the towel sheet length from the towel roll.
This dispenser 100 differs primarily from the dispenser 10 of the first
embodiment
by utilizing a roller drum 120 instead of the cutting drum 20, and including a
row
of cutting teeth 130 at the paper slot 19.
[0054] The roller drum 120 has a sufficient coefficient of friction that the
towel sheet applied thereon will be advanced through the dispenser 100 when
the roller drum 120 rotates. The components for feeding the towel sheet to the
roller drum 120 and out of the dispenser 100 are substantially the same as in
the
first embodiment of the dispenser 10. Since the roller drum does not contain
any
cutting mechanism, the paper is dispensed uncut through the paper slot 19. The
control circuit 82 is programmed so that the motor 60 advances the towel sheet
an appropriate length for a user's use; such length can be adjusted depending
on
the operator's preference.
[0055] As there is no retractable cutting knife 44, the roller drum 120 is not
connected to a return spring 32, and there is no cam path in the roller
assembly
18.
[0056] The cutting teeth 130 are located sufficiently deep inside the paper
slot that it is difficult for a user to inadvertently injure himself when
using the
dispenser 100. When the motor 60 advances a portion of the towel sheet out of
the dispenser, the user can tear a towel segment from the towel sheet using
the
cutting teeth 130.
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CA 02550357 2006-06-14
[0057] Referring particularly to Figure 16, right and left guides 140 are
shown which receives the right and left manual advance levers (not shown).
These levers are connected to a floating ratchet 150 and to a push button (not
shown). The floating ratchet 150 engages a set of teeth on an intermediate
drive
gear 160. The intermediate drive gear 160 rotatably couples the motor drum
drive gear 70 to a roller drum drive gear 170. When the push button is pushed,
the manual advance levers slide inwards along the guides 140, and move the
ratchet 150 such that the intermediate drive gear 160 is rotated clockwise as
shown in Figure 16 (drive direction). When the push button is returned back to
its start position, the ratchet 150 disengages from the intermediate drive
gear
160, in a manner that is well known in the art.
[0058] Like the first embodiment of the dispenser and referring particularly
to Figure 17, the motor drive gear 70 is provided with a one-way bearing 66
that
enables the motor 60 to drive the motor drive gear 70 in the drive direction,
and
allows the motor drive gear 70 to rotate freely in the opposite (counter
clockwise)
direction relative to the motor drive shaft. This enables the roller drum 120
to be
rotated by the push button even when the motor 60 is not operating, or allow
paper to be advanced by the push button at a faster rate than being advanced
by
the motor 60.
[0059] While the present invention has been described herein by the
preferred embodiments, it will be understood to those skilled in the art that
various changes may be made and added to the invention. The changes and
alternatives are considered within the spirit and scope of the present
invention.
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