Note: Descriptions are shown in the official language in which they were submitted.
CA 02342260 2001-03-27
MICROPROCESSOR CONTROLLED HANDS-FREE PAPER TOWEL
DISPENSER _
FIELD
The invention disclosed herein relates to towel dispensers and methods for
dispensing towels. More particularly, the invention disclosed herein relates
to
electric "hands-free" towel dispensers and methods for dispensing towels
without
use of the hands.
BACKGROUND
Towel dispensers are known and are shown in U.S. Patent Nos. 3,647,159,
4,131,044 and 4,165,138. For example, Bump, U.S. Patent No. 3,647,159 shows a
towel dispenser having an automatic towel length controlling means and roll
support
tensioning means. The towel dispenser disclosed generally comprises a shell,
means
within the shell for rotatably supporting a roll of paper toweling, a
frictional power
roller engaging a paper web from the roll, and means for limiting the length
of
individual paper towels withdrawn from the dispenser. The latter means
includes a
first gearlike member rotatable with the power roll, a second gearlike member
rotatable in response to rotation of the first gearlike member, a finger
carried by the
second gearlike member, a strap mounted for linear movement on the dispenser
between a first position and a second position, an abutment surface carried by
the
strap in a position intersecting the excursion path of the finger when the
strap is in a
first position, a limit abutment carried by the strap in a position
intersecting the
excursion path of the finger when the strap is in the second position, means
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CA 02342260 2001-03-27
temporarily holding the strap in the second position and means urging the
strap
toward the first position. The strap is moved toward the second position by
contact
of the finger with the abutment surface in response to rotation of the second
gearlike
member.
Electronic towel dispensers are also known. U.S. Patent Nos. 3,730,409,
3,971,607, 4,738,176, 4,796,825 and 4,826,262 each disclose electronic towel
dispensers. For example, in Ratti, U.S. Patent No. 3,730,409, a dispenser
comprises
a cabinet having a supply roll of paper towel therein and an electric motor-
driven
dispensing roll frictionally engaging the towel web for advancing it through a
dispensing opening past a movable cutter. The cutter is biased to a normal
rest
position and is movable to a severing position in response to the manual
cutting
action by a user. The dispenser further comprises a control circuit including
a
normally closed start switch and a normally open ready switch connected in a
series
between the motor and an associated power source. The normally open stop
switch
is in parallel with the ready switch. Program apparatus is coupled to the
cutter, the
motor and the control circuit and is responsive to movement of the cutter to
its
severing position for opening the start switch and closing the ready switch.
Movement of the cutter back to its normal rest position recloses the start
switch to
energize the motor. The program apparatus is responsive to operation of the
motor
for sequentially closing the stop switch then reopening the ready switch and
then
reopening the stop switch to de-energize the motor.
Finally, "hands-free" systems for controlling the operation of washroom
fixtures such as water faucets, soap dispensers and towel dispensers are
known.
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CA 02342260 2001-03-27
Examples of such hands-free systems are disclosed in U.S. Patent Nos.
4,796,825,
5,031,258, 5,060,323, 5,086,526, and 5,217,035. In Hawkins, U.S. Patent No.
4,796,825, an electronic paper towel dispenser is shown which permits paper
towels
to be dispensed from a supply roll by placing a hand or other object in front
of a
sensor located on the front of the supply cabinet. Dispensing of the paper
towels is
stopped when the hand is removed or when normal room lighting is not
available.
The dispensing of towels is controlled by a touchless switch for energizing a
motor
means.
The problem with prior hands-free electronic dispensers is that they require a
lo source of electricity such as AC current from a plug-in wall outlet to
power the
hands-free mechanism. This can be dangerous to a user, especially when the
dispenser is near a sink or other source of water. Another problem is that
many prior
hands-free dispensers are complicated devices which are expensive to
manufacture
and difficult to maintain in working order. Still another problem is that
prior hands-
free dispensers continue to dispense paper so long as the user's hand remains
in front
of the sensor. Also, if a change in ambient light occurs, prior hands-free
dispensers
have to be manually reset to adjust to a new light reference.
Therefore, it would be advantageous to provide improved towel dispensers
for automatically dispensing a length of towel in response to the movement of
an
object such as a user's hands. In this manner, a user can avoid contact with
viruses
or bacteria on the dispenser left by prior users' hands. It would be further
advantageous to provide energy-efficient hands-free dispensers which utilize
light
energy. It would also be advantageous to provide hands-free dispensers which
are
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CA 02342260 2001-03-27
simple in design, safe and easy to use. It would be even further advantageous
to
provide hands-free dispensers which are inexpensive to manufacture and free
from
problems such as inoperability due to jamming or changes in ambient light
conditions.
SUMMARY
A hands-free towel dispenser is provided which utilizes an active sensing
system, preferably an infra-red system, for detecting when a dispense of
toweling
should occur. The control for the dispenser is designed for low power use,
thereby
1o allowing the dispenser to be battery powered. The dispenser can also be
powered by
a solar panel, either in addition to or in place of, the batteries. Thus, the
dispenser
can be used in all lighting conditions.
In one aspect of the invention, as claimed, a hands-free towel dispenser is
provided. The hands-free dispenser comprises a housing for containing at least
one
roll of towels, a sensor for detecting an object, a dispensing mechanism for
dispensing a towel when the sensor detects the object, an electric power
source for
powering the dispensing mechanism, and control circuitry for controlling the
dispensing mechanism, where the control circuitry includes a microprocessor.
In another aspect of the invention, as claimed, a hands-free towel dispenser
is
provided. The dispenser comprises a housing for containing at least one roll
of
towels, a sensor for detecting an object, a dispensing mechanism for
dispensing a
towel when the sensor detects the object, an electric power source powering
the
dispensing mechanism, and control circuitry for controlling the dispensing
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mechanism. In this version, the sensor comprises a source of infra-red light
and a
sensor for sensing infra-red light reflected by the object.
These and various other advantages and features of novelty which
characterize the invention are pointed out with particularity in the claims
annexed
hereto and forming a part hereof. However, for a better understanding of the
invention, its advantages and objects obtained by its use, reference should be
made
to the drawings which form a further part hereof, and to the accompanying
description, in which there is described a preferred embodiment of the
invention.
DESCRIPTION OF THE DRAWINGS
These and other features of the invention will now be described with
reference to the drawings of preferred embodiments, which are intended to
illustrate
and not to limit the invention and in which:
FIG. 1 is a perspective view of an embodiment of the towel dispenser of the
invention;
FIG. 2 is a perspective view of the towel dispenser of FIG. 1 with the towel
roll removed;
FIG. 3 is a sectional view of a side elevation of the towel dispenser of FIG.
2;
FIG. 4 is a board layout for a mechanical plate used in the dispenser of the
invention;
FIG. 5 is a schematic diagram for the electric circuit of the invention;
FIG. 6 is a block diagram describing operation of the hands free dispenser;
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FIG. 7 is a block diagram describing operation of the safety shut off feature
of the dispenser; and
FIG. 8 is a block diagram describing how the battery is charged by the array
of one or more photovoltaic cells.
FIG. 9A is a sectional view of a side elevation of an alternative towel
dispenser.
FIG. 9B is a bottom view of the alternative towel dispenser.
FIG. 10 is another sectional side elevation view of the alternative towel
dispenser showing the location of the active sensing system and battery pack.
FIG. 11 is a sectional view looking down towards the bottom wall of the
cabinet, showing the relative positions of the LED and IR sensor.
FIG. 12 is a schematic diagram of the control circuit for the dispenser in
FIGS. 9 and 10.
FIGS. 13A and 13B illustrate the electrical circuitry used with the dispenser
of FIGS. 9 and 10.
FIG. 14 illustrates the battery pack used with the dispenser of FIGS. 9 and
10.
DETAILED DESCRIPTION
As used throughout the specification, including the claims, the term "hands-
free" means control of a dispensing mechanism without the need for use of
hands.
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In addition, as used throughout the specification, including the claims, the
term
"towel" refers generally to an absorbent paper or other suitable material used
for wiping
or drying.
As shown in FIG. 1, in a preferred embodiment of the invention, a hands-free
towel dispenser 10 comprises a cabinet 12 comprising a back wall 14, two side
walls
16, 18, a top wall 20, a bottom or base wall 22, and an openable and closeable
front
cover 24. The front cover 24 may be pivotally attached to the cabinet, for
example, by
hinge 26, for easy opening and closing of the cover 24 when a supply of towels
such as
main roll 28 is placed in the cabinet 12. The towel dispenser 10 may be
mounted to a
wall or other supporting member by any convenient means such as brackets,
adhesives,
nails, screws or anchors (not shown).
As shown in more detail in FIGS. 2, 3 and 4, the hands-free dispenser 10
further
comprises a dispensing mechanism for dispensing a length of towel to the
outside of the
dispenser 10. Such dispensing mechanism may comprise drive roller 32, pinch
roller
34, transfer bar 36 and roll support cup 38a and roll support arm 38b. The
dispensing
mechanism enables dispensing of a predetermined length of towel to the outside
of the
towel dispenser 10 through slot 40, where the towel can be grasped by the user
and torn
off along a serrated edge 43 of a blade 42.
The dispensing mechanism operates to dispense towels either from a main roll
28 or a stub roll 30. The means for controlling dispensing of paper from the
main roll
28 once the stub roll 30 has been depleted comprises a transfer bar 36, which
is
described in detail in U.S. Patent No. 4,165,138.
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As shown in FIGS. 1, 2 and 3, main roll 28 is first loaded into the cabinet 12
onto roll support cup 38a and roll support arm 38b located opposite each other
on
side walls 16, 18, respectively, and forming main roll station 48 (FIG. 1). A
length
of towel from main roll 28 is then threaded behind transfer bar 36 including a
fork
37a and a cam 37b, and over drive roller 32 so that towel sheeting 50 will be
pulled
between the drive roller 32 and the pinch roller 34 in a generally downward
motion
when the drive roller 32 is rotated by operation of a motor 88 shown in FIG.
4. As
the towel sheeting 50 is pulled downwardly, it is guided along a wall 52 of
the
serrated blade 42 and out slot 40.
The length of towel sheeting 50 dispensed from towel dispenser 10 can be set
to any desired length. Preferably, the dispenser 10 releases about ten to
twelve
inches of towel sheeting 50 per dispensing cycle. The towel sheeting 50 is
then
removed by tearing the length of dispensed towel sheeting 50 at the serrated
edge 43
of blade 42.
When the main roll 28 has been partially depleted, preferably to about a four-
inch diameter as indicated by low paper indicator 56, the dispenser cover 24
is
opened by an attendant, and the main roll 28 is moved down to a stub roll
station 54.
The main roll 28 then becomes stub roll 30 and enables a new main roll 28 to
be
loaded onto roll support cup 38a and roll support arm 38b in main roll station
48.
When stub roll 30 is completely depleted the new main roll 28 begins feeding
paper
50 between the drive roller 32 and pinch roller 34 out of the dispenser 10
when the
motor 88 is activated.
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When the low paper indicator 56 indicates that the new main roll 28 is low,
the attendant opens cover 24, an empty core (not shown) of stub ro1130 is
removed
from the stub roll station 54 and discarded, and new main roll 28 is dropped
into
position into the stub roll station 54 where it then becomes stub ro1130 and
continues
feeding. A main roll 28 is then positioned on the roll support cup 38a and
roll
support arm 38b. The basic transfer mechanism for continuously feeding towels
from a stub roll until completely used and then automatic transfer to a main
roll is
described in detail in U.S. Patent No. 4,165,138.
Hands-free operation of the dispenser 10 is effected when a person places an
object such as their hands in front of a photo sensor 82 shown in FIG. 4. The
photo
sensor 82 activates the motor 88 to dispense a predetermined length of towel
sheeting 50. The dispenser 10 has electric circuitry which, as will be
described
below with reference to FIGS. 4-8, ensures safe, efficient and reliable
operation of
the dispenser 10.
Referring now to FIG. 4, a cutaway view of a portion of the dispenser 10 is
shown. In FIG. 4, a circuit board 81 is mounted to a mechanical plate 80 of
the
dispenser 10. Note that the circuit board is mounted between the mechanical
plate
80 and the wall 16 of the cabinet 12. The photo sensor 82 is seated within a
mounting tube 83 and is coupled to the circuit board 81 by leads or wires 84,
85. As
will be described below with reference to FIG. 5, the photo sensor 82 reacts
to
changes in light intensity. Light passes from a room, through an opening 86 in
the
movable front cover 24 of the dispenser 10, to the photo sensor 82. A clear
plastic
lens 87 is fitted into the opening 86. The lens 87 prevents debris from
clogging or
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blocking the opening 86 which might prevent light from reaching the sensor 82.
The
lens 87 also prevents debris from falling into the dispenser 10 which might
cause the
dispenser 10 to malfunction.
Also shown in FIG. 4 is the motor 88 which is attached to the drive roller 32.
The motor 88, including a gearbox (not shown), are available from Skil
Corporation
in Chicago, Illinois. The motor 88 is placed partially within the drive roller
32 and
is powered by a rechargeable battery 90, also available from Skil Corporation.
The
battery 90 is coupled to the motor 88 via the circuit board 81 by wires or
leads 92,
94 which are connected or soldered to the circuit board 81.
A solar panel 96, is located on the top 20 of the dispenser 10 as shown in
FIG. 1. The solar panel 96 shown, which comprises an array of one or more
photovoltaic cells, is made by Solarex Corporation in Frederick, Maryland. The
solar panel 96 is coupled to the battery 90 and control circuitry 98 via the
circuit
board 81 by wires or leads 100, 102 which are connected or soldered to the
circuit
board 81 also.
The solar panel 96 provides power to control circuitry 98 for controlling the
dispensing mechanism of the dispenser 10. In a preferred embodiment, the solar
panel 96 provides power to control circuitry 98 (FIG. 5) which will manage
motion
sensing, rotation control, safety features, and recharging of the battery 90.
In a
second embodiment, the solar panel 96 provides power to the control circuitry
98
which will manage motion sensing, rotation control and safety features, but
the
battery 90 will be replaced at desired intervals and will not be recharged by
the
control circuitry 98. When the solar panel 96 is not exposed to light, the
solar panel
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96 does not supply power to the control circuitry 98 and the motor 88 cannot
be
turned on. The solar pane196 functions as an on-off switch for the dispenser
10 and
thereby prevents the battery 90 from becoming unnecessarily discharged when
the
lights are off. If the control circuitry 98 is not powered by the solar
pane196, the
motor 88 cannot be turned on.
Referring now to FIG. 5, a schematic diagram of the control circuitry 98 is
shown. The control circuitry 98 controls the "hands-free" operation of the
dispenser
10. More specifically, the control circuitry 98 controls andlor performs the
following functions: (1) sensing when an object such as a person's hand is in
front of
lo the photo sensor 82 and turning the motor 88 on; (2) sensing when the
proper length
of towel sheeting 50 has been dispensed and then turning the motor 88 off;
(3) sensing when towel sheeting 50 has jammed inside of the dispenser 10 and
turning the motor 88 off; (4) sensing when the front cover 24 of the dispenser
10 is
open and preventing operation of the motor 88; (5) creating a short delay,
preferably
about two seconds, between dispensing cycles; and (6) charging of the battery
90 by
the array of one or more photovoltaic cells 96.
The values of the components shown in the schematic diagram of FIG. 5 are
as listed below:
RESISTORS
R1= 1x106ohm R7= 1x106ohm
R2 = 520 x 103 ohm R8 = 20 x 103 ohm
R3 = 1 x 106 ohm R9 = 680 ohm
R4 = 3 x 106 ohm R 10 = 8 ohm
R5= 3.3x106ohm R11= 1x10ohm
R6 = lO x 106 ohm R12 = 1 x 106 ohm
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CAPACITORS
C l= 1 x 10-6 Farad C4 = 104 x 10-6 Farad
C2= 1 x 10-6 Farad C5 = 1 x 10-6 Farad
C3 = 104 x 10-6 Farad C6 = 1 x 10-6 Farad
Other Components
All diodes are part nos. IN4148 or IN914 from Diodes, Inc.
Operational Amplifiers ICIA and ICIB are on circuit board ICL7621DCPA
from Maxim.
Transistors Q1 and Q2 are part no. 2N3904 from National.
Transistor Q3 is part no. 2N3906 from National.
The solar panel is part nos. NSL-4532 or NSL-7142 from Solarex.
Reed switches RDl and RD2 are part no. MINS1525-052500 from CP-
CLAIRE.
Relay RLY1 is part no. TF2E-3V from AROMAT.
The photo sensor 82 shown is a Cadmium Sulfide ("CDS") motion detector
manufactured by Silonex Corporation located in Plattsburg, New York. The photo
sensor 82 is a variable resistance resistor. The resistance of the photo
sensor 82
changes depending on the amount of light to which the photo sensor 82 is
exposed.
If the amount of light on the photo sensor 82 is high, the photo sensor's
resistance
becomes relatively low. If the amount of light on the photo sensor 82 is low,
the
photo sensor's resistance becomes relatively high.
In ambient light, the photo sensor 82 has a certain resistance which causes
voltage VA to be less than a reference voltage VB. Voltage VA and reference
voltage
VB are the positive and negative inputs, respectively, of operational
amplifier IC1A.
When voltage VA is less than reference voltage VB, the operational amplifier
IC1A
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CA 02342260 2001-03-27
output voltage VMõ goes to negative, i.e., VM, is at zero voltage. When
voltage VM,
is at zero voltage, the motor 88 will not operate.
Note that the reference voltage VB is determined by and adjusts according to
the ambient light level in a room. Therefore, the reference voltage VB is not
preset
to any particular light level. A reference voltage circuit 104 sets the
reference
voltage VB according to the ambient light level of a room. Because the
reference
voltage circuit 104 sets the reference voltage VB according to the ambient
light level
in a room, no adjustments need to made to the dispenser 10 based on how high
or
low the ambient light level is for a particular room. Furthermore, the
combination of
the photo sensor 82 and the reference voltage circuitry 104 permit the photo
sensor
82 to trigger the dispenser 10 when a person's hand comes within approximately
10-
12 inches from the sensor 82.
The reference voltage circuit 104 includes resistors R2 and R3 and capacitor
Cl. Resistors R2 and R3 are connected to the positive terminal, SOLAR PANEL+,
of the solar panel 96 which provides a voltage B+ when the solar panel 96 is
exposed
to light. In ambient light, voltage VA is approximately .5(B+).
When a person places an obtrusion such as their hand within a predetermined
distance of the photo sensor 82, preferably within 10-12 inches, the amount of
light
reaching the photo sensor 82 is decreased sufficiently to cause the photo
sensor's
resistance to increase to a level where voltage VA becomes greater than
voltage VB
and thereby causes the output VM, of operational amplifier IC1A to be a
positive
voltage.
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The operational amplifier IC1A output voltage VM, is passed through diode
D1 and is coupled to the positive input of operational amplifier IC1B.
Reference
voltage Vc is provided between resistors R5 and R6 and is the negative input
of
operational amplifier IC1B. If voltage Vm, is greater than reference voltage
Vc, then
the output of the operational amplifier IC1B, VM2, is at a positive voltage.
When the
output voltage VMZ is at positive voltage, n-p-n transistor Ql is closed,
thereby
causing a current to flow through coil CL1 which in turn closes coil relay
RLY1.
When RLYI is closed, the motor 88 runs because the motor's positive terminal,
MOTOR+, is connected to the battery's positive terminal, BATTERY+.
In order to stop the motor 88 from turning after a predetermined amount of
towel sheeting 50 has been dispensed, a roller sensing circuit 106 is
provided. The
roller sensing circuit 106 includes a magnet, 108, an n-p-n transistor Q3, a
capacitor
C6, resistors R7 and R8 and a reed switch RD1. The magnet 108 is mounted on
drive roller 32. The magnet 108 activates or closes the reed switch RD1 when
the
magnet 108 is aligned with the reed switch RD1. When the reed switch RD1 is
closed, a one time voltage drop is made across capacitor C6. The voltage drop
across capacitor C6 turns on transistor Q3 which causes voltage VM, to drop to
less
than reference voltage Vc and therefore produces a negative output or zero
voltage
output VM, from operational amplifier ICIB and stops the motor 88 from
operating.
2o By changing the radius of the drive roller 32, the length of paper 50 that
is dispensed
can be varied.
The time it takes for the motor 88 to turn the drive roller 32 one full turn,
i.e.,
the time it takes for the magnet 108 to become aligned with reed switch RD1,
is
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CA 02342260 2001-03-27
approximately 0.47 seconds. When the drive roller 32 has made one full turn,
the
predetermined amount of towel sheeting 50 has been dispensed and the magnet
108
is aligned again with the reed sensor RD 1 to stop operation of the motor 88,
as
described above. Preferably, the motor 88 will power an approximately 3-4 inch
diameter roller for one revolution, sufficient to dispense approximately 10-12
inches
of paper towe150. If the reed sensor RD1 is not activated within 1.0 second,
e.g., if
a paper jam occurs, a safety timer circuit 110 turns the motor 88 off.
The safety timer circuit 110 includes capacitor C2 and resistor R4. If the
reed switch RD1 does not sense the magnet 108 within 1.0 second, the safety
timer
circuit 110 causes voltage Vn,,, to drop below reference voltage Vc and
thereby
causes output voltage VMZ to be at zero volts and turns the motor 88 off.
When the front cover 24 is open, e.g., to add towel sheeting 50 in the
dispenser 10, the motor 88 is prevented from operating by a door safety
circuit 120.
The door safety circuit 120 includes resistors R5 and R6, a reed switch RD2
and a
magnet 121. One lead 122 of the reed switch RD2 is attached to resistor R5 and
the
other lead 124 is attached to ground G2. Reference voltage Vc is created
between
resistors R5 and R6. When the front cover 24 is open, the reed switch RD2 is
open
and causes voltage Vc to be higher than voltage VM, and therefore causes the
output
voltage, Vr,1z, of operational amplifier IC1B to be at zero voltage. Note that
voltage
VM2 is never higher than voltage B.
When the front cover 24 is closed, the magnet 121 causes the reed switch
RD2 to close and allows reference voltage Vc to be less than voltage VM,,
which in
CA 02342260 2001-03-27
turn causes the output voltage VM2 of operational amplifier IC1B to be at
positive
voltage and turns the motor 88 on.
In ambient room light, the solar panel 96 generates enough current to power
the control circuitry 98. In the preferred embodiment (shown in FIG. 5), the
solar
panel 96 generates enough current to also charge the battery 90. In this
preferred
embodiment, a positive lead, SOLAR PANEL+, of the solar panel 96, is connected
to battery charging circuitry 126.
The battery charging circuitry 126 includes a diode D5, resistors R11 and
R16, a capacitor C4 and a p-n-p transistor Q2. The positive lead, SOLAR
PANEL+,
of the solar panel 96 charges capacitor C4 through resistor R16. When
capacitor C4
is charged to a certain voltage level, preferably approximately 1.2 volts
higher than
the battery voltage B+, resistor R11 biases the capacitor C4 to discharge
through the
p-n-p transistor Q2 and into the positive terminal, BATTERY+, of the battery
90.
As long as light reaches the solar panel 96, the battery charging process will
be
repeated and the solar panel 96 continually charges the capacitor C4 and
battery 90.
In the second embodiment, the solar panel 96 only provides power to the
control circuitry 98. Disposable, D-cell batteries or other disposable
batteries can be
used to power the motor 88, instead of the rechargeable battery 90. Because
the
control circuitry 98 is powered by the solar panel 96, the motor 88 will not
operate
unless there is light in the room, thus preventing the disposable batteries
from
becoming unnecessarily discharged. After the disposable battery has been fully
discharged, the disposable battery can be replaced.
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CA 02342260 2001-03-27
The control circuitry 98 also includes delay circuitry 112 to prevent the
dispenser 10 from starting a new cycle of dispensing towel sheeting 50 until a
predetermined time after the motor 88 has turned off from a prior dispensing
cycle.
The predetermined time is preferably approximately 2 seconds. The delay
circuitry
122 includes a diode D2, resistor R3, and capacitor Cl.
When voltage Vn,1z is high, the motor 88 is running and causing towel
sheeting 50 to be dispensed from the dispenser 10. When Vn,,z is high,
capacitor Cl
is charge to a very high level, forcing reference voltage VB very high. It
takes
approximately 2 seconds for VB to return to its ambient light level setting.
During
lo that time, if a person places their hand in front of the photo sensor 82,
voltage VA
will not be forced higher thanVB. As a result, the motor 88 cannot be turned
on
again until approximately 2 seconds after it has been turned off. This
prevents a
continual discharge of towel sheeting 50 from the dispenser which could cause
the
battery 90 to discharge and the motor 88 to burn out.
The manner in which the motor 88 is turned on is described in the flowchart
of FIG. 6. The motor 88 cannot be turned on if there is not enough ambient
light in
the room to power the control circuitry 98. The solar panel 96 acts as an "on-
off'
switch for the dispenser 10 and will not permit the dispenser 10 to dispense
towel
sheeting 50 unless there is sufficient light in the room. If there is
sufficient light in
the room to power the control circuitry 98, the various checks, which have
been
described above with reference to the circuitry in FIG. 5, are shown in the
flowchart
of FIG. 6. These checks are performed before the motor 88 is turned on.
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CA 02342260 2001-03-27
The manner in which the motor 88 is turned off, which has been explained
above with reference to FIG. 5, is described in the flowchart in FIG. 8.
Similarly,
the charging of the battery 90 by the solar pane196, which has been explained
above
with reference to FIG. 5, is described in the flowchart of FIG. 8.
Figures 9-14 illustrate another embodiment of a hands-free towel dispenser
200 according to the principles of the invention. The dispenser 200 utilizes
active
infra-red (IR) sensing to trigger a dispense of paper toweling. The dispenser
200
also incorporates additional unique features that operate together with the
active IR
to provide an improved dispenser.
The use of active IR permits very short range sensing, such as within a range
of about 5 inches to about 10 inches. It is important that the sensing
distance not be
too great, in order to prevent sensing of an individual or object from far
away and
thereby prevent an unintended dispense of paper toweling. The dispenser 200 of
this
embodiment floods a target area with IR light and then senses only that IR
reflected
by an object, such as a user's hand(s). The IR is emitted in short pulses at a
predetermined frequency, which not only requires low energy, but prevents the
dispenser from being activated by ambient lighting since the ambient lighting
is
unable to synchronize with the pulses and frequency of the IR light emitted by
the
dispenser.
Turning to Figures 9 and 10, the dispenser 200 includes a cabinet 12 and
front cover 24 as in the dispenser 10. Other elements in the dispenser 200
corresponding to similar elements in the dispenser 10 are referenced by the
same
numerals.
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CA 02342260 2001-03-27
The dispenser 200 further includes a spray door 202 that is slideably
mounted on the bottom wall 22 for sliding movement in the direction of the
arrows
in Fig. 9 between a first position, shown in Fig. 9, covering the slot 40, and
a second
position (not shown) to the left of the first position shown in Figure 9 in
which the
slot 40 is uncovered. The door 202 is slideably supported at each end thereof
in rails
205a, 205b formed on the bottom wall 22 whereby the door can be actuated
manually between the first and second positions. The door 202 includes a
magnet
204 thereon that interacts with a spray door switch 206 located on the cabinet
12.
The switch 206 is part of control circuitry (to be later described) for the
dispenser 200. The magnet 204 and switch 206 function in such a manner that
when
the door 202 is in the position shown in Fig. 9 covering the slot 40, the
switch 206 is
closed and the dispenser 200 is prevented from operating. When the door 202 is
slid
backward to its second position with the slot uncovered, the switch 206 opens
and
permits operation of the dispenser 200. Thus, the door 202 permits the
dispenser
200 to be cleaned without getting the paper towels wet and without the
dispenser
200 dispensing towel.
Referring now to Figure 10, the dispenser 200 includes a circuit board 208
that is mounted to the plate 80. As in the previous embodiment, the circuit
board
208 is mounted between the plate 80 and the wall 16 of the cabinet 12. A
battery
pack 210 for powering the dispenser 200 is further provided and is coupled to
the
board 208 by leads or wires 212a, 212b, 212c. The battery pack 210 supplements
the solar panel 96, and in low lighting conditions at which the solar panel 96
is
ineffective, the battery pack 210 will totally support the electronics in the
dispenser
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CA 02342260 2001-03-27
200. Thus, the dispenser is able to function in all light conditions,
including in the
dark. A motor 214, similar to the motor 88, is also provided, and is coupled
to the
circuit board 208 via leads or wires 216a, 216b.
The dispenser 200 further includes an IR sensor 218 disposed on a sensor
board 220. The IR sensor 218 is seated at the base of a sensor tube 222 which
projects forwardly from the cabinet 12 so that the open end of the sensor tube
222 is
disposed proximate the front cover 24. The front cover 24 is formed from a
material
that is transparent to IR thereby allowing IR light to pass through the cover.
Since
the cover 24 allows IR light to pass therethrough, a hole to permit passage of
IR
light need not be formed in the cover. In addition, as seen in Figure 11, an
LED 224
for emitting IR light is connected to the sensor board 220. The LED 224 is
disposed
within a tube 226 disposed next to the tube 222, with the tube 226 projecting
forwardly so that the open end thereof is disposed adjacent the opening in the
front
cover whereby IR light is projected out from the dispenser 200. As shown in
Figure
10, the sensor board 220 is coupled to the circuit board 208 by a pair of
leads or
wires 228.
The IR sensor 218 and LED 224 form a portion of an active IR sensing
circuit that is used to trigger a dispense of paper towels from the dispenser
200. The
LED 224 emits IR light at a predetermined frequency. The light pulses will
reflect
off of a user's hand when the user's hand is sufficiently close and in proper
position.
The reflected light is picked up by the IR sensor 218 which causes the control
system of the dispenser to dispense a predetermined length of paper towels.
---- ---------
CA 02342260 2001-03-27
Figure 10 further illustrates the position of a magnet 230 (shown in dashed
lines) that, like the magnet 121, is positioned in the front cover 24 for
interaction
with a reed switch 232. The switch 232 is activated by the magnet 230, with
the
switch being closed by the magnet when the front cover is closed. When the
switch
is closed, the dispenser 200 is able to dispense toweling when triggered by
the IR
sensing circuit. Otherwise, when the front cover is open, the switch 232 is
open and
the dispenser cannot dispense paper toweling. In addition, a reed switch 234
(shown
in dashed lines) is provided which interacts with a magnet 236 (shown in
Figure 11)
on the roller for sensing the revolutions of the roll. Moreover, Figure 10
shows the
location of a low battery LED 238 that is illuminated when a low battery
condition
exists in the battery pack 210 or when a paper jam occurs.
Figure 12 is a schematic illustration of the control circuitry 250 used to
control the dispenser 200. A microprocessor 252 receives inputs from Delay 1
switch 254, Delay 2 switch 256, towel length switch 258, sensor length switch
260,
IR sensing circuit 262, and the switches 206, 232, 234. The use of a
microprocessor
reduces costs and adds flexibility and functionality.
The input from the Delay 1 switch 254 causes the microprocessor 252 to wait
a predetermined length of time, such as 1 or 2 seconds, between accepting
input
from the IR sensing circuit 262. The input from the Delay 2 switch 256 is
similar to
the input from the Delay 1 switch, except that the predetermined length of
time is
greater, such as 3 seconds. Both Delay 1 and Delay 2 specify the amount of
time
that a user has to wait before a second dispense of paper toweling can occur.
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CA 02342260 2001-03-27
The towel length switch 258 causes the microprocessor 252 to look for a
predetermined number of activations, such as 1 or 2 activations, of the switch
234 to
thereby control the length of the paper towel that is dispensed.
The sensor length switch 260 increases the power to the LED 224, thereby
sending more IR light out of the LED. An increase in IR light makes detection
by
the sensing circuit 262 easier, and effectively increases the distance that
the sensing
circuit 262 can detect a user's hand or the like.
The length of toweling dispensed, the delay between cycles, and the LED
power (i.e. sensitivity) can be changed by a dip switch 261 located on the
circuit
Io board 208.
The switch 206 associated with the spray door 202 must be open to permit
operation of the dispenser 200. When the switch 206 is open, the spray door
202 is
open, so that the slot 40 is uncovered and paper toweling can be dispensed
therethrough. However, if the switch 206 is closed, a signal is sent to the
microprocessor 252 which prevents the microprocessor from cycling the motor
214.
Likewise, the switch 232 associated with the front cover 24 must be closed by
the
magnet 230 in order to permit operation of the dispenser. If the switch 232 is
open,
a signal is sent to the microprocessor 252 which prevents the microprocessor
from
cycling the motor 214
The switch 234 is designed to close when the magnet 236 in the roller passes
nearby, which sends a signal letting the microprocessor 252 know that the roll
has
completed one rotation. When this signal is sent, the microprocessor 252 shuts
the
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CA 02342260 2001-03-27
motor off 214. The switch 234 then opens waiting for the next activation by
the IR
sensing circuit 262.
In addition to receiving signals, the microprocessor sends out a signal to the
motor 214 to control the operation thereof. The signal is sent to the motor
214 when
the microprocessor 252 receives a signal from the IR sensing circuit 262,
provided
all necessary inputs, such as from the switches 262, 232 and the proper amount
of
delay has expired, are provided.
Further, the microprocessor 252 cycles the LED 224 at a predetermined
frequency, preferably 7Hz. The LED 224 emits IR light at that frequency, which
reflect off of the user's hand for detection by the sensor 218. The IR sensing
circuit
262 amplifies and/or filters the signal as necessary before sending the signal
to the
microprocessor. As indicated above, the sensor length switch 260 can be used
to
alter the power sent to the LED 224. The amount of power sent to the LED
determines how close the user's hand needs to be to the IR sensor 218 in order
to
properly reflect light to the sensor 218.
Moreover, the microprocessor 252 will also count the signal inputs from the
IR sensing circuit 262 and determine whether the time delay between signal
inputs is
roughly equivalent to the LED frequency. The microprocessor 252 preferably is
designed to cycle the motor 214 only if two signals at the prescribed
frequency have
2o been received by the IR sensing circuit 262 and microprocessor 252.
Further still, the microprocessor 252 turns on the low battery LED 238 when
a low battery condition of the battery pack 210 is indicated. A low battery
condition
is indicated by determining the cycle time between turning the motor 214 on
and
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CA 02342260 2001-03-27
receiving input from the switch 234. If the cycle time is greater than a
predetermined time, such a between 1-2 seconds, preferably 1.2 seconds, the
low
battery LED is illuminated, thereby providing an indication that the battery
pack 210
needs replacement.
It is important that the dispenser 200 be designed to operate with low power
and with high reliability, because the dispenser 200 has to be able to be in
operational use for one or more years without intervention on the part of a
user.
Therefore, the control circuitry 250 further includes an oscillator circuit
264 that
provides an input to the microprocessor 252. The oscillator circuit 264 is
designed
lo to turn the power to the microprocessor 252 on/off at a predetermined
frequency
thereby reducing the power consumption by the microprocessor. The preferred
frequency is 7 Hz, although a higher or lower frequency could be used as well.
In addition to reducing power consumption, the oscillator circuit 264 resets
the microprocessor logic so that if the microprocessor gets into a faulted
state, the
logic will be reset, thereby allowing the microprocessor to restart from a
stored
program, which is similar to rebooting a computer when the software stops
functioning properly. This resetting operation happens at the oscillating
frequency,
such as 7 times per second, and thus the program can never stay in a faulty
condition.
Figures 13A and 13B illustrate the details of the control circuitry 250, with
Figure 13A illustrating the circuitry on the circuit board 208 and Figure 13B
illustrating the details of the IR sensing circuit 262 on the sensor board
220.
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CA 02342260 2001-03-27
In the sensing circuit 262, the LED 224 that provides the IR light is driven
by
a transistor driver 266 located on the board 208. The remainder of the
circuitry in
Figure 13B is for amplifying and/or filtering the signal received by the IR
sensor 218
which is preferably a photodiode.
As shown in Figure 13A, the oscillator circuit 264 includes a plurality of
Schmitt triggers that form a very low frequency oscillator so that the
oscillator
circuit 264 is able to oscillate all the way down to an applied voltage of
about 1 volt.
Therefore, as the battery pack dies down, the oscillator keeps running. The
oscillator circuit 264 is preferably oscillated at a frequency of about 7 Hz
so that it
wakes up the microprocessor 252 seven times a second from being asleep and
resets
it. Further, the circuit 264 provides all the basic timing of the control
circuitry 250
so the microprocessor 252 does not have to do any timing itself. Therefore,
the
microprocessor does not have to be awake to keep track of time, which means
that it
can go asleep and reduce power consumption radically. The circuit 264 is
coupled
to the reset of the microprocessor 252 on pin 1.
The control circuitry 250 further includes a processor clock 268. The clock
268 preferably operates at 8 MHz. This fast clock speed allows the
microprocessor
252 to complete all of its functions as fast as possible, so that the
microprocessor
252 can go back to sleep, via the oscillator circuit 264, as soon as possible.
The
result is that very little energy is consumed. Previously, processor clocks
have been
designed to operate slow so they consume less energy. However, the inventor's
have
discovered that running a processor clock, such as the clock 268, as fast as
it can
CA 02342260 2001-03-27
allows the microprocessor to return to its sleep state faster, thereby
consuming less
energy.
The control circuitry 250 further includes a circuit 270 that forces the
microprocessor 252 to awaken when the roller is turning during a paper
toweling
dispense. The circuit 270 includes a lead FRS that is coupled to the switch
234 and
receives a signal therefrom each time the magnet 236 on the roller turns past
the
switch 234. When the roller turns and the magnet 236 rotates past the switch
234, a
signal is received over FRS and into a trigger 272 which generates a pulse
that is
sent via IRQ to wake-up the microprocessor 252 and shut the motor 214 off.
A motor control circuit 274 is also included for controlling operation of the
motor 214.
An options control circuit 276 is further provided for controlling Delay 1,
Delay 2, towel length and sensor length as described above with respect to
Figure
12. The dip switch 261 permits adjustment of these options.
The solar power control circuit 278 controls operation of the solar panel 96.
The circuit 278 includes a diode 280 that prevents the power from the battery
pack
210 from damaging the solar cells. The circuit 278 further includes a diode
282 that
limits the voltage that is supplied by the solar panel 96. The inventors have
discovered that in bright lighting conditions, the solar panel may produce too
much
voltage that could overpower the circuitry 250. The diode 282 limits the
voltage
supplied by the panel 96 and thereby prevents overpowering of the circuitry
250.
The LED 238 further acts as a paper jam indicator, in addition to the low
battery indicator. As indicated above, a low battery state is determined by
the cycle
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CA 02342260 2001-03-27
time of the roll that dispenses paper. Thus, timing how long it takes for the
paper to
come out provides an indication of how weak the battery pack 210 is. When it
takes
too much time, a low battery state is indicated and the LED flashes when the
door 24
is opened. A paper jam condition is triggered when the magnet 236 in the
roller is
not sensed. If the magnet 236 does not return in about 2 seconds, the motor
214 will
shutoff. After three consecutive "no magnet returns", the dispenser 200 will
shut
down to further sensor input, until the dispenser has been reset. The
dispenser is
reset by opening and closing the cover 24.
Thus, the dispenser 200 is able to work in all light conditions. Further, the
dispenser consumes low power, so that batteries can be used to power the
dispenser,
with the dispenser being able to operate for long periods of time between
servicing
without frequent battery changes.
The battery pack 210 is illustrated in detail in Figure 14. The battery pack
210 includes a plurality of D cells 290, in this case six D cells, with an AA
cell 292
disposed on top of the D cells and connected in series therewith. The D cells
290 are
stacked two each in series to get 3V, with three stacks in parallel to obtain
enough
amperage. The A cell gets the voltage of the pack 210 up to 4.5V which is
sufficient
to operate the circuitry 250. Other battery pack configurations could be used
instead
of the pack 210, provided the battery pack provided sufficient voltage to
operate the
circuitry.
The embodiments of the inventions disclosed herein have been discussed for
the purpose of familiarizing the reader with novel aspects of the invention.
Although preferred embodiments have been shown and described, many changes,
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CA 02342260 2001-03-27
modifications, and substitutions may be made by one having skill in the art
without
necessarily departing from the spirit and scope of the invention.
28
