Towel DispenserFree Patent Search

Hands-free paper towel dispenser

Towel Dispenser Abstract
A towel dispenser comprising an electronic power system, which includes an array of one or more photovoltaic cells for energizing a control circuitry which, in turn, controls operation of the dispenser. The control circuitry is responsive to a sensing device, comprised of a motion detector, which senses rapid changes in light, which in turn, activates the dispensing of a length of paper towels when an object, such as a user's hand, is moved in front of the sensing device.

Towel Dispenser Claims
We claim:

1. A hands-free towel dispenser comprising:

(a) a housing means for containing at least one roll of towels;

(b) a sensing means for detecting an object;

(c) a dispensing means for dispensing a predetermined length of towel when said sensing means detects the object;

(d) an electric power source for powering said dispensing means;

(e) control circuitry for controlling the dispensing means and controlling said predetermined length of towel; and

(f) an array of one or more photovoltaic cells for energizing said control circuitry.

2. The hands-free paper towel dispenser of claim 1 wherein said control circuitry provides for a delay between cycles of towel dispensing.

3. The hands-free towel dispenser of claim 1 wherein said sensing means comprises a variable resistor which changes in response to changes in light levels.

4. The hands-free towel dispenser of claim 1 wherein said electric power source is a battery.

5. The hands-free towel dispenser of claim 4 wherein said electric power source is a rechargeable battery.

6. The hands-free paper towel dispenser of claim 5 wherein said array of one or more photovoltaic cells also charges said rechargeable battery.

7. The hands-free towel dispenser of claim 1 wherein said housing means comprises a movable front cover.

8. The hands-free towel dispenser of claim 7 wherein said dispensing means includes means for detecting when said cover is open and preventing dispensing of a towel until said cover is closed.

9. The hands-free towel dispenser of claim 1 wherein said dispensing means comprises a drive roller mounted in said housing means and a motor inside said drive roller.

10. A hands-free towel dispenser comprising:

(a) a housing structured to contain at least one roll of towel;

(b) a sensor connected to said housing;

(c) a dispensing mechanism comprising a drive roller mounted in said housing and a motor mounted inside said drive roller;

(d) an electric power source connected to said housing and structured to power said dispensing mechanism; and

(e) a control circuitry structured to control the dispensing mechanism and providing a delay between cycles of towel dispensing;

wherein said dispensing mechanism is structured to dispense a predetermined length of towel when said sensor detects an object and said control circuitry is structured to control said predetermined length of said towel.

11. A method of dispensing paper towel from at least one roll of paper from a hands-free paper towel dispenser comprising a housing, a dispensing mechanism for dispensing paper from the dispenser, a sensing mechanism for

sensing the presence of an object, a control circuitry for controlling the dispensing mechanism, a power source for powering the dispensing mechanism, and an array of one or more photovoltaic cells, comprising the steps of:

sensing when an object is within a predetermined distance from the sensing mechanism;

energizing the control circuitry from the array of one or more photovoltaic cells; and

dispensing a predetermined amount of paper from the dispenser.

12. A hands-free towel dispenser comprising:

(a) a housing;

(b) a sensing mechanism connected to said housing;

(c) a dispensing mechanism connected to said sensing mechanism;

(d) an electric power source for powering said dispensing mechanism; and

(e) a control circuitry for controlling the dispensing mechanism;

wherein the dispensing mechanism is structured to dispense a predetermined length of towel when the sensing mechanism detects an object and the control circuitry provides a delay between cycles of towel dispensing and said control circuitry is energized by an array of one or more photovoltaic cells.

13. The hands-free towel dispenser of claim 12 wherein said dispensing mechanism comprises a drive roller mounted in said housing and a motor mounted in said drive roller.

14. The hands-free towel dispenser of claim 12 wherein said control circuitry is structured to not operate said dispensing mechanism when a door of said housing is open.

15. A hands-free towel dispenser comprising:

(a) a housing;

(b) a sensing mechanism connected to said housing;

(c) a dispensing mechanism connected to said sensing mechanism;

(d) an electric power source for powering said dispensing mechanism; and

(e) a control circuitry for controlling the dispensing mechanism;

wherein said control circuitry is energized by an array of one or more photovoltaic cells.

16. The hands-free towel dispenser of claim 15 wherein said control circuitry is structured to not operate said dispensing mechanism when a door of said housing is open.

17. The hands-free towel dispenser of claim 15 wherein said dispensing mechanism comprises a drive roller mounted in said housing and a motor inside said drive roller.

18. The hands-free towel dispenser of claim 15 wherein the control circuitry provides for a delay between cycles of towel dispensing.

19. A hands-free towel dispenser comprising:

(a) a housing means for containing at least one roll of towels;

(b) a sensing means for detecting an object;

(c) dispensing means for dispensing a predetermined length of towel when said sensing means detects the object, said dispensing means comprising a drive roller mounted in said housing means and a motor inside said drive roller;

(d) an electric power source for powering said dispensing means; and

(e) a control circuitry for controlling the dispensing means, providing a delay between cycles of towel dispensing, and controlling said predetermined length of towel.

20. The hands-free towel dispenser of claim 19 wherein said dispensing means further includes means for sensing when said drive roller has dispensed a predetermined amount of paper.

21. The hands-free towel dispenser of claim 19 wherein said control circuitry is energized by an array of one or more photovoltaic cells.

22. The hands-free towel dispenser of claim 19 wherein said control circuitry is structured to not operate said dispensing means when a door of said housing is open.

Patent Information Search Body

Towel Dispenser Description
FIELD OF THE INVENTION

The invention relates to towel dispensers and methods for dispensing towels. More particularly, the invention relates to electric "hands-free" towel dispensers and methods for dispensing towels without use of the hands.

BACKGROUND OF THE INVENTION

Towel dispensers are well known and are shown in U.S. Pat. Nos. 3,647,159, 4,131,044 and 4,165,138. For example, Bump, U.S. Pat. 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 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 well known. U.S. Pat. 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. Pat. 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. Examples of such hands-free systems are disclosed in U.S. Pat. Nos. 4,796,825, 5,031,258, 5,060,323, 5,086,526, and 5,217,035. In Hawkins, U.S. Pat. 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 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 is an object of the present invention 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 is a further object to provide energy-efficient hands-free dispensers which utilize light energy. It is another object to provide hands-free dispensers which are simple in design, safe and easy to use. It is yet another object 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 OF THE INVENTION

The invention comprises a hands-free towel dispenser comprising a unique electronic power system. The electronic power system comprises a an array of one or more photovoltaic cells which energizes a unique control circuitry which in turn controls operation of the dispenser. The control circuitry is responsive to a sensing device which activates the dispensing of a length of paper towels when an object such as a user's hand is moved in front of the sensing device.

The hands-free dispenser of the invention comprises:

(a) a housing means for containing towels;

(b) a sensing means for detecting an object such as a person's hand;

(c) a dispensing means for dispensing a towel when said sensing means detects the object;

(d) an electric power source for powering said dispensing means;

(e) control circuitry for controlling the dispensing means; and

(f) an array of one or more photovoltaic cells for energizing said control circuitry.

Preferably, the sensing means comprises a motion detector which senses rapid changes in light. Also, preferably, the electric power source is a rechargeable battery which is in turn recharged by the array of one or more photovoltaic cells.

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;

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.

DETAILED DESCRIPTION OF THE INVENTION

The term "hands-free" means control of a dispensing means without the need for use of hands.

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 means for dispensing length of towel to the outside of the dispenser 10. Such dispensing means may comprise drive roller 32, pinch roller 34, transfer bar 36 and roll support cup 38a and roll support arm 38b. The dispensing means 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 means 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. Pat. No. 4,165,138, the disclosure of which is incorporated by reference herein.

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.

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 roll 30 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 roll 30 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. Pat. 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 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, Ill. 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.

An array of one or more photovoltaic cells 96, is located on the top 20 of the dispenser 10 as shown in FIG. 1. The array of one or more photovoltaic cells 96 shown is made by Solarex Corporation in Frederick, Md. The array of one or more photovoltaic cells 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 array of one or more photovoltaic cells 96 provides power to control circuitry 98 for controlling the dispensing means of the dispenser 10. In a preferred embodiment, the array of one or more photovoltaic cells 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 array of one or more photovoltaic cells 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 array of one or more photovoltaic cells 96 is not exposed to light, the array of one or more photovoltaic cells 96 does not supply power to the control circuitry 98 and the motor 88 cannot be turned on. The array of one or more photovoltaic cells 96 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 array of one or more photovoltaic cells 96, 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 and/or performs the following functions: (1) sensing when an object such as a person's hand is in front of 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 solar panel 96.

The values of the components shown in the schematic diagram of FIG. 5 are as listed below:

______________________________________ RESISTORS R1 = 1 .times. 10.sup.6 ohm R7 = 1 .times. 10.sup.6 ohm R2 = 520 .times. 10.sup.3 ohm R8 = 20 .times. 10.sup.3 ohm R3 = 1 .times. 10.sup.6 ohm R9 = 680 ohm R4 = 3 .times. 10.sup.6 ohm R10 = 8 ohm R5 = 3.3 .times. 10.sup.6 ohm R11 = 1 .times. 10 ohm R6 = 10 .times. 10.sup.6 ohm R12 = 1 .times. 10.sup.6 ohm CAPACITORS C1 = 1 .times. 10.sup.-6 Farad C4 = 104 .times. 10.sup.-6 Farad C2 = 1 .times. 10.sup.-6 Farad C5 = 1 .times. 10.sup.-6 Farad C3 = 104 .times. 10.sup.-6 Farad C6 = 1 .times. 10.sup.-6 ______________________________________ Farad

OTHER COMPONENTS

All diodes are part nos. IN4148 or IN914 from Diodes, Inc.

Operational Amplifiers IC1A and IC1B 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 array of one or more photovoltaic cells are part nos. NSL-4532 or NSL-7142 from Solarex.

Reed switches RD1 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, N.Y. 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 V.sub.A to be less than a reference voltage V.sub.B. Voltage V.sub.A and reference voltage V.sub.B are the positive and negative inputs, respectively, of operational amplifier IC1A. When voltage V.sub.A is less than reference voltage V.sub.B, the operational amplifier IC1A output voltage V.sub.M1, goes to negative, i.e., V.sub.M1 is at zero voltage. When voltage V.sub.M1 is at zero voltage, the motor 88 will not operate.

Note that the reference voltage V.sub.B is determined by and adjusts according to the ambient light level in a room. Therefore, the reference voltage V.sub.B is not preset to any particular light level. A reference voltage circuit 104 sets the reference voltage V.sub.B according to the ambient light level of a room. Because the reference voltage circuit 104 sets the reference voltage V.sub.B 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 C1. Resistors R2 and R3 are connected to the positive terminal, Photovoltaic Cell, of the array of one or more photovoltaic cells 96 which provides a voltage B.sub.+ when the solar panel 96 is exposed to light. In ambient light, voltage V.sub.A is approximately 0.5 (B.sub.+)

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 V.sub.A becomes greater than voltage V.sub.B and thereby causes the output V.sub.M1 of operational amplifier IC1A to be a positive voltage.

The operational amplifier IC1A output voltage V.sub.M1 is passed through diode D1 and is coupled to the positive input of operational amplifier IC1B. Reference voltage V.sub.C is provided between resistors R5 and R6 and is the negative input of operational amplifier IC1B. If voltage V.sub.M1 is greater than reference voltage V.sub.C, then the output of the operational amplifier IC1B, V.sub.M2, is at a positive voltage. When the output voltage V.sub.M2 is at positive voltage, n-p-n transistor Q1 is closed, thereby causing a current to flow through coil CL1 which in turn closes coil relay RLY1. When RLY1 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 V.sub.M1 to drop to less than reference voltage V.sub.C and therefore produces a negative output or zero voltage output V.sub.M1 from operational amplifier IC1B and stops the motor 88 from operating. 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 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 RD1 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 towel 50. 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 V.sub.M1 to drop below reference voltage V.sub.C and thereby causes output voltage V.sub.M2 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 V.sub.C is created between resistors R5 and R6. When the front cover 24 is open, the reed switch RD2 is open and causes voltage V.sub.C to be higher than voltage V.sub.M1 and therefore causes the output voltage, V.sub.M2, of operational amplifier IC1B to be at zero voltage. Note that voltage V.sub.M2 is never higher than voltage B.sub.+.

When the front cover 24 is closed, the magnet 121 causes the reed switch RD2 to close and allows reference voltage V.sub.C to be less than voltage V.sub.M1, which in turn causes the output voltage V.sub.M2 of operational amplifier IC1B to be at positive voltage and turns the motor 88 on.

In ambient room light, the array of one or more photovoltaic cells 96 generates enough current to power the control circuitry 98. In the preferred embodiment (shown in FIG. 5), the array of one or more photovoltaic cells 96 generates enough current to also charge the battery 90. In this preferred embodiment, a positive lead, Photovoltaic Cell, of the 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, Photovoltaic Cell, of the array of one or more photovoltaic cells 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.sub.+, 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 array of one or more photovoltaic cells 96, the battery charging process will be repeated and the array of one or more photovoltaic cells 96 continually charges the capacitor C4 and battery 90.

In the second embodiment (not shown), the array of one or more photovoltaic cells 96 only provides power to the control circuitry 98. Disposable, D-cell batteries (not shown) 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 array of one or more photovoltaic cells 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.

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 C1.

When voltage V.sub.M2 is high, the motor 88 is running and causing towel sheeting 50 to be dispensed from the dispenser 10. When V.sub.M2 is high, capacitor C1 is charge to a very high level, forcing reference voltage V.sub.B very high. It takes approximately 2 seconds for V.sub.B to return to its ambient light level setting. During that time, if a person places their hand in front of the photo sensor 82, voltage V.sub.A will not be forced higher than V.sub.B. 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 array of one or more photovoltaic cells 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.

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 array of one or more photovoltaic cells 96, which has been explained above with reference to FIG. 5, is described in the flowchart of FIG. 8.

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, modifications, and substitutions may be made by one having skill in the art without necessarily departing from the spirit and scope of the invention.

 

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