US20170258278A1 - Electronically controlled dispenser for dispensing flexible sheet material - Google Patents

Abstract

A method of grounding a dispenser. A low impedance path is connected to elements internal to the dispenser. The low impedance path is also connected to a surface contact spring which is adapted to contact an external mounting surface when the dispenser is affixed thereto. Static electrical charge accumulated on the elements is discharged through the low impedance path and the surface contact spring to the external mounting surface.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. application Ser. No. 14/185,172 filed Feb. 20, 2014, now U.S. Pat. No. 9,661,958, which is a continuation of U.S. application Ser. No. 12/131,368 filed Jun. 2, 2008, now U.S. Pat. No. 8,684,297, which is a continuation of U.S. application Ser. No. 11/329,766 filed Jan. 10, 2006, now U.S. Pat. No. 7,387,274, which is a continuation of U.S. application Ser. No. 10/807,988 filed Mar. 23, 2004, now U.S. Pat. No. 7,017,856, which is a continuation of U.S. application Ser. No. 09/966,124 filed Sep. 27, 2001, now U.S. Pat. No. 6,871,815, which is a continuation-in-part of U.S. application Ser. No. 09/780,733, filed Feb. 9, 2001, now U.S. Pat. No. 6,592,067. The priorities of the foregoing applications are hereby claimed and the entirety of their disclosures incorporated herein by reference.
FIELD OF THE INVENTION
• This invention relates to the field of grounding for static electricity build-up in dispensing systems.
BACKGROUND
• As is readily apparent, a long-standing problem is to keep paper towel available in a dispenser and at the same time use up each roll as completely as possible to avoid paper waste. As part of this system, one ought to keep in mind the person who refills the towel dispenser. An optimal solution would make it as easy as possible and as “fool-proof” as possible to operate the towel refill system and have it operate in such a manner as the least amount of waste of paper towel occurs. This waste may take the form of “stub” rolls of paper towel not being used up.
• Transfer devices are used on some roll towel dispensers as a means of reducing waste and decreasing operating costs. These transfer devices work in a variety of ways. The more efficient of these devices automatically begin feeding from a reserve roll once the initial roll is exhausted. These devices eliminate the waste caused by a maintenance person when replacing small rolls with fresh rolls in an effort to prevent the dispenser from running out of paper. These transfer devices, however, tend to be difficult to load and/or to operate. Consequently, these transfer devices are less frequently used, even though they are present.
• The current transfer bar mechanisms tend to require the maintenance person to remove any unwanted core tube(s), remove the initial partial roll from the reserve position, and position the initial partial roll into the now vacant stub roll position. This procedure is relatively long and difficult, partly because the stub roll positions in these current paper towel dispensers tend to be cramped and difficult to get to.
• In order to keep a roll available in the dispenser, it is necessary to provide for a refill before the roll is used up. This factor generally requires that a “refill” be done before the current paper towel roll is used up. If the person refilling the dispenser comes too late, the paper towel roll will be used up. If the refill occurs too soon, the amount of paper towel in the almost used-up roll, the “stub” roll, will be wasted unless there is a method and a mechanism for using up the stub roll even though the dispenser has been refilled. Another issue exists, as to the ease in which the new refill roll is added to the paper towel dispenser. The goal is to bring “on-stream” the new refill roll as the last of the stub roll towel is being used up. If it is a task easily done by the person replenishing the dispensers, then a higher probability exists that the stub roll paper towel will actually be used up and also that a refill roll be placed into service before the stub roll has entirely been used up. It would be extremely desirable to have a paper towel dispenser which tended to minimize paper wastage by operating in a nearly “fool proof” manner with respect to refilling and using up the stub roll.
• As an enhancement and further development of a system for delivering paper towel to the end user in as cost effective manner and in a user-friendly manner as possible, an automatic means for dispensing the paper towel is desirable, making it unnecessary for a user to physically touch a knob or a lever.
• It has long been known that the insertion of an object with a dielectric constant into a volume with an electrostatic field will tend to modify the properties which the electrostatic field sees. For example, sometimes it is noticed that placing one hand near some radios will change the tuning of that radio. In these cases, the property of the hand, a dielectric constant close to that of water, is enough to alter the net capacitance of a tuned circuit within the radio, where that circuit affects the tuning of the RF signal being demodulated by that radio. In 1973 Riechmann (U.S. Pat. No. 3,743,865) described a circuit which used two antenna structures to detect an intrusion in the effective space of the antennae. Frequency and amplitude of a relaxation oscillator were affected by affecting the value of its timing capacitor.
• The capacity (C) is defined as the charge (Q) stored on separated conductors with a voltage (V) difference between the conductors:
• 
  C=Q/V.
• For two infinite conductive planes with a charge per unit area of σ, a separation of d, with a dielectric constant, of the material between the infinite conductors, the capacitance of an area A is given by:
• 
  C=∈Aσ/d
• Thus, where part of the separating material has a dielectric constant ∈₁and part of the material has the dielectric constant ∈₂, the net capacity is:
• 
  C=∈₁A₁σ/d+∈₂A₂σ/d
• The human body is about 70% water. The dielectric constant of water is 7.18×10⁻¹⁰farads/meter compared to the dielectric constant of air (STP): 8.85×10⁻¹²farads/meter. The dielectric constant of water is over 80 times the dielectric constant of air. For a hand thrust into one part of space between the capacitor plates, occupying, for example, a hundredth of a detection region between large, but finite parallel conducting plates, a desirable detection ability in terms of the change in capacity is about 10⁻⁴About 10⁻²is contributed by the difference in the dielectric constants and about 10⁻²is contributed by the “area” difference.
• Besides Riechmann (1973), other circuits have been used for, or could be used for proximity sensing.
• An important aspect of a proximity detector circuit of this type is that it be inexpensive, reliable, and easy to manufacture. A circuit made of a few parts tends to help with reliability, cost and ease of manufacture. Another desirable characteristic for electronic circuits of this type is that they have a high degree of noise immunity, i.e., they work well in an environment where there may be electromagnetic noise and interference. Consequently a more noise-immune circuit will perform better and it will have acceptable performance in more areas of application.
• The presence of static electric charges on a surface, which is in proximity to electronic systems, creates a vulnerability to the presence of such charges and fields. Various approaches to grounding the surfaces are used to provide a pathway for the static electric charges to leave that surface. Since static electric charges may build up from one or two kilovolts to 30 or more kilovolts in a paper-towel-dispensing machine, the deleterious effect on electronic components can be very real. An approach involves using an existing ground such as an AC ground “green wire” in a three-wire 110-volt system. The grounding is achieved by attaching to the ground wire or conduit. The grounding wire is ultimately connected to an earth ground. This approach is widely used in the past and is well known. However, many locations where a motorized paper towel dispenser might be located do not have an existing AC system with ground.
• In cases where grounded receptacles are not present, a ground may be produced by driving a long metal rod, or rods, into the earth. Another method for grounding utilizes a cold water pipe, which enters and runs underground. Roberts (U.S. Pat. No. 4,885,428) shows a method of grounding which includes electrical grounding receptacles and insulated ground wire connected to a single grounding point, viz., a grounding rod sunk into the earth. This method of Roberts avoids grounding potential differences. Otherwise grounding each grounding receptacle to a separate grounding rod likely finds in-ground variation of potential. Soil conditions such as moisture content, electrolyte composition and metal content are factors that can cause these local variations in grounding potential. The cost and inconvenience of installing a grounding rod system may be prohibitive to support an installation of a motorized paper towel dispenser.
• However, in many instances it may not be possible to have either of these approaches available. Therefore, a desirable grounding approach would be to ground to a local surface, termed a local ground, which may be a high impedance object, which is only remotely connected to an earth ground. In particular, dispensing paper towels, and other materials, can produce static electric build up charge during the dispensing cycle. In the past the static electricity build up, when it was produced on a lever crank or pulled-and-tear type systems paper towel dispensers, had little or no effect on the performance of the dispensing system. The most that might happen would be the user receiving a “static-electric shock.” Although unpleasant this static electric shock is not injurious to the person or to the towel dispenser.
• Today, however, dispensing systems are often equipped with batteries. These batteries may operate a dispensing motor. However, in addition there may other electronic circuitry present, for example, a proximity sensing circuit might utilize low power CMOS integrated circuits. These CMOS integrated circuits are particularly vulnerable to static electric charge build up. It is desirable to protect these electronic from the static electric discharge.
• In analyzing the static charge build up one may look at the charge separation occurring during a ripping operation of the towel or from the action of the paper on rollers or other items in the dispensing pathway.
• A ground may be regarded as a sink of charge. This sink may be large as in the case of an actual earth ground. On the other hand, this grounding may relate to a relatively smaller sink of charge, a local ground. The sink of charge may be a wall or a floor or a part of such objects. The static charge build up may be in one sense regarded as a charge in a capacitor separated from a ground (as the second surface of the capacitor) by a high impedance material. The charge can't reach an earth ground as the wall material does not conduct electricity well.
• There is, however, another mode of dispersing the charge on the surface. The isolated charges are of the same sign. The charges tend to repel each other. Therefore, the tendency is to spread out on the surface. Where the surface is completely dry and of a non-conductive material, then the actual conduction is very low. The motion of the charges, whether electrons or positive or negative ions, may be impeded by surface tension (Van der Waal) forces between the charges (electrons, negative ions or positive ions). Therefore, in the case where the surface is somewhat damp, even at a low 5% to 10% relative humidity, it is likely that various impurities are present in the water so as to form a weak, conducting electrolyte solution. At higher humidity this provides for an even more efficient way of dispersing the charges on the surface.
SUMMARY OF THE INVENTION
• The present invention is directed toward a method of grounding a dispenser to control the build-up of static electricity. A low impedance path is connected to elements internal to the dispenser. The low impedance path is also connected to a surface contact spring which is adapted to contact an external surface to which the dispenser is mounted. Static electrical charge which accumulates on the internal elements of the dispenser is discharged through the low impedance path and the contact spring to the external surface.
BRIEF DESCRIPTION OF THE DRAWINGS
• For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
• FIG. 1 is a side elevation of the dispenser with the cover closed, with no internal mechanisms visible;
• FIG. 2 is a perspective view of the dispenser with the cover closed, with no internal mechanisms visible;
• FIG. 3 shows a view of the carousel support, the locking bar and the transfer bar;
• FIG. 4A is a perspective view of the of the dispenser with the carousel and transfer bar, fully loaded with a main roll and a stub roll;
• FIG. 4B is a side view of the locking bar showing the placement of the compression springs;
• FIG. 4C shows the locking mechanism where the locking bar closest to the rear of the casing is adapted to fit into a mating structure in the rear casing;
• FIG. 5 is a perspective, exploded view of the carousel assembly;
• FIG. 6A is a side elevation view of the paper feeding from the stub roll while the tail of the main roll is positioned beneath the transfer bar;
• FIG. 6B is a side elevation view of the stub roll is completely exhausted, so that the transfer bar tucks the tail of the main roll into the feed mechanism;
• FIG. 7A is a side elevation view of the carousel ready for loading when the main roll reaches a specific diameter;
• FIG. 7B is a side elevation view of the locking bar being pulled forwardly to allow the carousel to rotate 180°, placing the main roll in the previous stub roll position;
• FIG. 7C shows the location of the extension springs which tend to maintain the transfer bar legs in contact with the stub roll;
• FIG. 7D shows the cleanable floor of the dispenser;
• FIG. 8A shows a schematic of the proximity circuit;
• FIG. 8B (prior art) shows the schematic for the National Semiconductor dual comparator LM393;
• FIG. 9 shows the U1 waveforms at pin 1 (square wave A), pin 5 (exponential waveform B) and pin 6 (exponential waveform C);
• FIG. 10A is a perspective view of a paper towel dispenser with an access hole for the grounding wire and shows a molded rib which prevents the low impedance grounding wire from contacting an idler gear;
• FIG. 10B is a perspective view a screw boss and molded ribs for attaching the wall contact spring grounding clip to the chassis of the dispenser;
• FIG. 10C is another perspective view of the screw boss and ribs for attaching the wall contact spring grounding clip to the chassis;
• FIG. 11A is a perspective view of the gear cover with a molded rib that holds the spring contact in place;
• FIG. 11B is a perspective view of the grounding wire contacting the spring clip and entering an access hole toward its other end;
• FIG. 11C is a side elevational view of the towel dispenser showing the grounding wire, the spring contact which connects to the grounding wire and also connects to the wall contact spring grounding clip;
• FIG. 12 is a perspective view of the path of the grounding wire after it enters the access hole;
• FIG. 13A is a rear, perspective view of the opening for the wall contact spring grounding clip of the towel dispenser;
• FIG. 13B is a perspective view of the wall contact spring grounding clip in place in the back of the paper-towel-dispensing unit;
• FIG. 14 is a perspective view of the static charge flow path including the nib roller to the nib roller shaft, the compression spring, the spring contact, and the grounding wire; and
• FIG. 15 is an elevational view showing the compression spring.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is merely made for the purpose of describing the general principles of the invention. The scope of the invention should be determined with reference to the claims.
• An embodiment of the invention comprises a carousel-based dispensing system with a transfer bar for paper towels, which acts to minimize actual wastage of paper towels. As an enhancement and further development of a system for delivering paper towel to the end user in a cost effective manner and in as user-friendly manner as possible, an automatic means for dispensing the paper towel is desirable, making it unnecessary for a user to physically touch a knob or a lever. An electronic proximity sensor is included as part of the paper towel dispenser. A person can approach the paper towel dispenser, extend his or her hand, and have the proximity sensor detect the presence of the hand. The embodiment of the invention as shown here, is a system, which advantageously uses a minimal number of parts for both the mechanical structure and for the electronic unit. It has, therefore, an enhanced reliability and maintainability, both of which contribute to cost effectiveness.
• An embodiment of the invention comprises a carousel-based dispensing system with a transfer bar for paper towels, which acts to minimize actual wastage of paper towels. The transfer bar coupled with the carousel system is easy to load by a service person; consequently it will tend to be used, allowing stub rolls to be fully utilized. In summary, the carousel assembly-transfer bar comprises two components, a carousel assembly and a transfer bar. The carousel rotates a used-up stub roll to an up position where it can easily be replaced with a full roll. At the same time the former main roll which has been used up such that its diameter is less than some p inches, where p is a rational number, is rotated down into the stub roll position. The tail of the new main roll in the upper position is tucked under the “bar” part of the transfer bar. As the stub roll is used up, the transfer bar moves down under spring loading until the tail of the main roll is engaged between the feed roller and the nib roller. The carousel assembly is symmetrical about a horizontal axis. A locking bar is pulled out to unlock the carousel assembly and allow it to rotate about its axis, and is then released under its spring loading to again lock the carousel assembly in place.
• A side view,FIG. 1, of thedispenser20 with thecover22 in place shows an uppercircular bulge24, providing room for a full roll of paper towel, installed in the upper position of the carousel. The shape of the dispenser is such that the front cover tapers inwardly towards the bottom to provide a smaller dispenser volume at the bottom where there is a smaller stub roll of paper towel. The shape tends to minimize the overall size of the dispenser.FIG. 2 shows a perspective view of thedispenser20 withcover22 in place and the circular (cylindrical)bulge24, together with the sunrise-like setback26 on thecover22, which tends to visually guide a hand toward thepseudo-button28, leading to activation of a proximity sensor (not shown). A light emitting diode (LED)130 is located centrally to thepseudo-button28. The LED130 (FIG. 3) serves as an indication that thedispenser20 is on, and dispensing towel. TheLED130 may be off while the dispenser is not dispensing. Alternatively, theLED130 may be lit (on), and when thedispenser20 is operating, theLED130 might flash. TheLED130 might show green when thedispenser20 is ready to dispense, and flashing green, or orange, when thedispenser20 is operating to dispense. Any similar combination may be used. The least power consumption occurs when theLED130 only lights during a dispensing duty cycle. The sunrise-like setback26 (FIG. 2) allows a hand to come more closely to the proximity sensor (not shown).
• FIG. 3 shows the main elements of thecarousel assembly30. Thecarousel arms32 have friction reducing rotating papertowel roll hubs34, which are disposed into the holes of a paper towel roll (66,68,FIG. 4A). The lockingbar36 serves to lock and to release the carousel for rotation about itsaxis38. The lockingbar36 rides on one of the corresponding bars40. The twocorresponding bars40 serve as support bars. Cross-members42 serve as stiffeners for thecarousel assembly30, and also serve as paper guides for the paper to be drawn over and down to thefeed roller50 and out thedispenser20. These cross members are attached in a rigid fashion to the correspondingbars40 and in this embodiment do not rotate.
• Thelegs46 of thetransfer bar44 do not rest against the friction reducing rotating papertowel roll hubs34 when there is nostub roll68 present but are disposed inward of theroll hubs34. Thebar part88 of thetransfer bar44 will rest against a structure of the dispenser, for example, the top ofmodular electronics unit132, when nostub roll68 is present. Thebar part88 of thetransfer bar44 acts to bring the tail of a new main roll of paper towel66 (FIG. 4A) down to thefeed roller50 which includes intermediate bosses146 (FIG. 3) andshaft144. The carousel assembly is disposed within the fixedcasing48. The cover is not shown.
• Feed roller50 serves to feed thepaper towels66,68 (FIG. 4A) being dispensed onto thecurved dispensing ribs52. Thecurved dispensing ribs52 are curved and have a low area of contact with the paper towel dispensed (not shown). If thedispenser20 gets wet, thecurved dispensing ribs52 help in dispensing the paper towel to get dispensed by providing low friction and by holding the dispensing towel off of the wet surfaces it would otherwise contact.
• Thefeed roller50 is typically as wide as the paper roll, and includes driverollers142 andintermediate bosses146 on thedrive shaft144. The working drive rollers or drive bosses142 (FIG. 3) are typically an inch or less in width, with intermediate bosses146 (FIG. 3) located between them.Intermediate bosses146 are slightly less in diameter than the drive rollers or drivebosses142, having a diameter 0.015 to 0.045 inches less than the drive rollers or drivebosses142. In this embodiment, the diameter of theintermediate bosses146 is 0.030 inches less than thedrive roller142. This configuration of drive rollers or drivebosses142 andintermediate bosses146 tends to prevent the dispensing paper towel from becoming wrinkled as it passes through the drive mechanism and reduces friction, requiring less power to operate thefeed roller50.
• Acontrol unit54 operates amotor56.Batteries58 supply power to themotor56. Amotor56 may be positioned next to thebatteries58. A light60, for example, a light-emitting diode (LED), may be incorporated into a low battery warning such that the light60 turns on when the battery voltage is lower than a predetermined level.
• Thecover22 of the dispenser is preferably transparent so that the amount of the main roll used (see below) may be inspected, but also so that the batterylow light60 may easily be seen. Otherwise an individual window on anopaque cover22 would need to be provided to view thelow battery light60. Another approach might be to lead out the light by way of a fiber optic light pipe to a transparent window in thecover22.
• In a waterproof version of the dispenser, a thin piece of foam rubber rope is disposed within a u-shaped groove of the tongue-in-groove mating surfaces of thecover22 and thecasing48. Thedispensing shelf62 is a modular component, which is removable from thedispenser20. In the waterproof version of thedispenser20, thedispensing shelf62 with the molded turningribs52 is removed. By removing the modular component, dispensingshelf62, there is less likelihood of water being diverted into thedispenser20 by thedispensing shelf62, acting as a funnel or chute should a water hose or spray be directed at thedispenser20, by the shelf and wetting the paper towel. The paper towel is dispensed straight downward. A most likely need for a waterproof version of the dispenser is where a dispenser is located in an area subject to being cleaned by being hosed down. Thedispenser20 has an on-off switch which goes to an off state when thecover22 is pivoted downwardly. The actual switch is located on the lower face of thenodule54 and is not shown.
• In one embodiment, the user may actuate the dispensing of a paper towel by placing a hand in the dispenser's field of sensitivity. There can be adjustable delay lengths between activations of the sensor.
• There is another aspect of the presence of water on or near thedispenser20. A proximity sensor (not visible) is more fully discussed below, including the details of its operation. However, as can be appreciated, the sensor detects changes of capacitance such as are caused by the introduction of an object with a high dielectric constant relative to air, such as water, as well as a hand which is about 70% water. An on-off switch140 is provided which may be turned off before hosing down and may be turned on manually, afterwards. Theswitch140 may also work such that it turns itself back on after a period of time, automatically. Theswitch140 may operate in both modes, according to mode(s) chosen by the user.
• A separate “jog” off-onswitch64 is provided so that a maintenance person can thread thepaper towel66 by holding a spring loadedjog switch64 which provides a temporary movement of thefeed roller50.
• FIG. 4A shows thedispenser case48 with thecarousel assembly30 andtransfer bar44. Thecarousel assembly30 is fully loaded with amain roll66 and astub roll68, both mounted on thecarousel arms32 to rotate on the rotating reduced friction paper towel roll hubs34 (only shown from the back of the carousel arms32). In thecarousel assembly30, the twocarousel arms32, joined by correspondingbars40 andcross members42, rotate in carousel fashion about a horizontal axis defined by the carouselassembly rotation hubs38. The lockingbar36 is supported, or carried, by a correspondingbar40. The correspondingbar40 provides structural rigidity and support. The lockingbar36 principally serves as a locking mechanism. Eachpaper towel roll66,68 has an inner cardboard tube which acts as a central winding core element, and which provides in a hole inpaper towel roll66,68 at each end for engaging thehubs34.
• FIG. 5 shows thecarousel assembly30 in exploded, perspective view. The number of parts comprising this assembly is small. From a reliability point of view, the reliability is increased. From a manufacturing point of view, the ease of manufacture is thereby increased and the cost of manufacture is reduced. The material of manufacture is not limited except as to the requirements of cost, ease of manufacture, reliability, strength and other requirements imposed by the maker, demand.
• When the main roll,66 (FIG. 4A) and thestub roll68, (FIG. 4A) are in place, thecarousel arms32 are connected by theserolls66 and68 (FIG. 4A). Placingcross-members42 to connect thecarousel arms32 with the locking36 and corresponding40 bar results in better structural stability, with racking prevented. The lockingbar36, which was shown as a singleunit locking bar36 in the previous figures, acts as a lockingbar36 to lock thecarousel assembly30 in the proper orientation. It acts also as the release bar, which when released, allows thecarousel assembly30 to rotate. Two compression springs70,72 are utilized to center the lockingbar36.
• FIG. 4B is a side view of the locking bar showing the placement of the compression springs. The compression springs70,72 also tend to resist the release of the lockingbar36, insuring that a required force is needed to unlock the lockingbar36. The required force is typically between 0.5 lbf and 3.0 lbf, or more. In this embodiment, the force is 2.0 lbf when the spring in a fully compressed position, and 1.1 lbf when the spring is in the rest position. In the rest position, the forces of the opposing springs offset each other.
• The actual locking occurs as shown inFIG. 4C. The lockingbar36 closest to the rear of thecasing48 is adapted to fit into a generallyu-shaped mating structure118 which is adapted to hold the lockingbar36 and prevent it and thecarousel assembly30 from rotating. When the lockingbar36 is pulled away from the rear of thecasing48, the lockingbar36 is disengaged from themating structure118. The mating structure has an upper “high”side120 and a lower “low”side122, where the low side has a “ramp”124 on its lower side. As the lockingbar36 is pulled out to clear thehigh side120, thecarousel assembly30 is free to rotate such that the top of thecarousel assembly30 rotates up and away from the back of thecasing48. As thecarousel assembly30 begins to rotate, the user releases the lockingbar36 which, under the influence of symmetrically placed compression springs70,72 returns to its rest position. As the carousel assembly rotates, the end of thesymmetrical locking bar36 which originally was disposed toward the user now rotates and contacts theramp124. A locking bar spring, e.g.,70 or72, is compressed as the end of the lockingbar36 contacting theramp124 now moves up theramp124. The end of the lockingbar36 is pressed into the space between thelow side122 and thehigh side120, as the end of the lockingbar36 slides past thelow side122. A locked position for thecarousel assembly30 is now reestablished.
• FIG. 5 shows thecarousel arms32 adapted to receive the loading of a new roll of towel66 (FIG. 4A). Thearms32 are slightly flexible and bent outward a small amount when inserting a paper towel roll66 (FIG. 4A) between twoopposite carousel arms32. A friction reducing rotating papertowel roll hub34 is inserted into a hole of a paper towel roll66 (FIG. 4A), such that oneroll hub34 is inserted into a hole on each side of the paper towel roll66 (FIG. 4A). Also shown inFIG. 5 are the tamperresistant fasteners74, which attach the friction-reducing rotating papertowel roll hubs34 to thecarousel arms32.
• FIG. 5 shows thesurface76 of theroll hubs34 and thesurface78 of thecarousel arms66, which contact each other. These contact surfaces76,78 may be made of a more frictionless material than that of which thecarousel arms32 and theroll hubs34 are made. For example, a plastic such as polytetrafluoroethylene (PTFE), e.g., TEFLON®, may be used, as a thin layer on each of the contacting surfaces. Thepaper towel dispenser20 and its components may be made of, including but not limited to, plastic, metal, an organic material which may include but is not limited to wood, cardboard, treated or untreated, a combination of these materials, and other materials for batteries, paint, if any, and waterproofing.
• FIG. 6A shows thepaper80 feeding from thestub roll68 while thetail82 of themain roll66 is positioned beneath thetransfer bar44. The legs (visible leg46, other leg not shown) of thetransfer bar44 rests against the stub roll. When the diameter of thestub roll68 is larger by a number of winds of paper towel than theinner roll84, thelegs46 of thetransfer bar44 dispose thebar88 of thetransfer bar44 to be rotated upward from thefeed roller50.
• FIG. 6B shows the situation where thestub roll68 is exhausted, so that thetransfer bar44 tucks thetail82 of themain roll66 into thefeed mechanism86.FIG. 6B shows thestub roll68 position empty, as the stub roll has been used up. Thestub roll core84 is still in place. As thestub roll68 is used up, thelegs46 of thetransfer bar44 move up toward the stub roll core (inner roll)84, and thebar88 of the transfer bar is disposed downward toward thefeed roller50 and toward the top of a structural unit of the dispenser20 (FIG. 2), such as the top of the electronics module132 (FIG. 3). Initially themain roll66 is in reserve, and itstail82 in an “idling” position such that it is under thetransfer bar44. Themain roll66 and itstail82 are not initially in a “drive” position. However, as thestub roll68 is used up, the downward motion of the bar transfer bar,44 driven by its spring loading, brings thebar88 of thetransfer bar44 down to engage themain roll tail82 with thefeed roller50.
• FIG. 7A shows thecarousel assembly30 ready for loading when themain roll66 reaches a specific diameter. The diameter of themain roll66 may be measured by comparison of that diameter with the widened “ear” shape122 (FIG. 4A) on each end of thecarousel arms32. That part of eachcarousel arm32 is made to measure a critical diameter of amain roll66. Thecarousel assembly30 is tilted forward when it is locked. Thecarousel assembly30 may rotate unassisted after the lockingbar36 is released, due to the top-heavy nature of the top roll. That is, the torque produced by the gravitational pull on the main-roll66 is larger than that needed to overcome friction and the counter-torque produced by the nowempty stub roll68.
• FIG. 7B shows the process of loading where the service person pulls the lockingbar36 and allows the carousel to rotate 180°, placing themain roll66 in theprevious stub roll68 position. Now a new fullsized roll66 can be loaded onto themain roll66 position. Thetransfer bar44 automatically resets itself. Thetransfer bar44 is spring loaded so as to be disposed with thetransfer bar legs46 pressed upward against thestub roll68 or thestub roll core84. Thetransfer bar legs46 are adapted to be disposed inward of theroll hubs34 so thebar88 of thetransfer bar44 will have a positive stop at a more rigid location, in this case, the top of the electronics module132 (FIG. 2).
• FIG. 7C shows the extension springs126,128 which tend to maintain thetransfer bar legs46 in contact with thestub roll68 orstub roll core84. Thetransfer bar44 contains the two extension springs126,128. The spring forces are typically 0.05 lbf to 0.5 lbf in thebar44 lowered position and 0.2 lbf to 1.0 lbf in thebar44 raised position. In this embodiment, the spring forces are 0.2 lbf in the lowered position and 0.43 lbf in the raised position. The force of the twosprings126,128 is additive so that thetransfer bar44 is subject to a total spring force of 0.4 lbf in the lowered position and 0.86 lbf in the raised position.
• While modular units (FIG. 7D) such as theelectronics module132, themotor56 module, and thebattery case150, are removable, they fit, or “snap” together so that the top of theelectronics unit132, the top of themotor56 module and remaining elements of the “floor”148 of the dispensingunit20 form a smooth, cleanable surface. Paper dust and debris tend to accumulate on thefloor148 of thedispenser20. It is important that thedispenser20 is able to be easily cleaned as part of the maintenance procedure. A quick wiping with a damp cloth will sweep out and pick up any undesirable accumulation. The removablemodular dispensing shelf64 may be removed for rinsing or wiping.
• Thefeed roller50 may be driven by amotor56 which in turn may be driven by a battery orbatteries58, driven off a 100 or 220V AC hookup, or driven off a transformer which is run off an AC circuit. The batteries may be non-rechargeable or rechargeable. Rechargeable batteries may include, but not be limited to, lithium ion, metal hydride, metal-air, nonmetal-air. The rechargeable batteries may be recharged by, but not limited to, AC electromagnetic induction or light energy using photocells.
• Afeed roller50 serves to feed the paper towel being dispensed onto thecurved dispensing ribs52. A gear train (not visible) may be placed under housing86 (FIG. 3) for driving the feed roller. A control unit54 (FIG. 3) for a motor56 (FIG. 3) may be utilized. A proximity sensor (not shown) or a hand-operatedswitch64 may serve to turn themotor56 on and off.
• As an enhancement and further development of a system for delivering paper towel to the end user in as cost effective manner and user-friendly manner as possible, an automatic means for dispensing the paper towel is desirable, making it unnecessary for a user to physically touch a knob or a lever. Therefore, a more hygienic dispenser is present. This dispenser will contribute to less transfer of matter, whether dirt or bacteria, from one user to the next. The results of washing ones hands will tend to be preserved and hygiene increased.
• An electronic proximity sensor is included as part of the paper towel dispenser. A person can approach the paper towel dispenser, extend his or her hand, and have the proximity sensor detect the presence of the hand. Upon detection of the hand, a motor is energized which dispenses the paper towel. It has long been known that the insertion of an object with a dielectric constant into a volume with an electromagnetic field will tend to modify the properties, which the electromagnetic field sees. The property of the hand, a dielectric constant close to that of water, is enough to alter the net capacitance of a suitable detector circuit.
• An embodiment of the invention comprises a balanced bridge circuit. SeeFIG. 8A. Thecomponent U1A90 is a comparator (TLC3702158) configured as an oscillator. The frequency of oscillation of this component,U1A90, of the circuit may be considered arbitrary and non-critical, as far as the operation of the circuit is concerned. The period of the oscillator is set by theelements C_ref92,R_hys94, the trim resistance,R_trim96, where the trim resistance may be varied and the range resistors R_range152 are fixed. The resistors R_range152 allow limits to be placed on the range of adjustment, resulting in an easier adjustment. The adjustment band is narrowed, since only part of the total resistance there can be varied. Consequently a single potentiometer may be used, simplifying the adjustment ofR_trim96. A value forR_range152 for the schematic shown inFIG. 8A might be 100 kΩ.R_trim96 might have an adjustment range of 10 kΩ to 50 kΩ. The output signal atpin 198 ofcomponent U1A90 is a square wave, as shown at line A ofFIG. 9.C_ref92 is charged by the output along withANT100, both sustaining the oscillation and measuring the capacitance of the adjacent free space. The signals resulting from the charging action are applied to a second comparator,U1B102, atpin 5104 andpin 6106 (FIG. 8A). These signals appear as exponential waveforms, as shown at lines B and C ofFIG. 9.
• The simplest form of a comparator is a high-gain differential amplifier, made either with transistors or with an op-amp. The op-amp goes into positive or negative saturation according to the difference of the input voltages because the voltage gain is typically larger than 100,000, the inputs will have to be equal to within a fraction of a millivolt in order for the output not to be completely saturated. Although an ordinary op-amp can be used as comparator, there are special integrated circuits intended for this use. These include the LM306, LM311, LM393154 (FIG. 8A), LM393V, NE627 andTLC3702158. The LM393V is a lower voltage derivative of theLM393154. TheLM393154 is an integrated circuit containing two comparators. TheTLC3702158 is a micropower dual comparitor with CMOS push-pull156 outputs.FIG. 8B (prior art) is a schematic which shows the different output structures for the LM393 and the TLC3702. The dedicated comparators are much faster than the ordinary op-amps.
• The output signal atpin 198 ofcomponent U1A90, e.g., aTL3702158, is a square wave, as shown inFIG. 8A. Two waveforms are generated at the inputs of the second comparator,U2B102. Thefirst comparator90 is running as an oscillator producing a square-wave clocking signal, which is input, to the clock input of the flip-flop U2A108, which may be, for example, a Motorola D flip-flop, No. 14013.
• Running the first comparator as a Schmitt trigger oscillator, thefirst comparator U1A90 is setup to have positive feedback to the non-inverting input, terminal 3110. The positive feedback insures a rapid output transition, regardless of the speed of the input waveform.R_hys94 is chosen to produce the required hysteresis, together with the bias resistors R_bias1112 andR_bias2114. When these two bias resistors,R_bias1112,R_bias2114 and the hysteresis resistor,R_hys94, are equal, the resulting threshold levels are ⅓ V+ and ⅔ V+, where V+158 is the supply voltage. The actual values are not especially critical, except that the threeresistors R_bias1112,R_bias2114 andR_hys94, should be equal, for proper balance. The value of 294 kΩ may be used for these three resistors, in the schematic shown inFIG. 8A.
• An external pull-up resistor,R_pullup1116, which may have a value, for example, of47052, is only necessary if an open collector comparator such as anLM393154 is used. Thatcomparator154 acts as an open-collector output with a ground-coupled emitter. For low power consumption, better performance is achieved with a CMOS comparator, e.g., TLC3702, which utilizes a CMOS push-pull output156. The signal atterminal 3110 of U1 A charges acapacitor C_ref92 and also charges anANT sensor100 with a capacitance whichC_ref92 is designed to approximate. A value for C_reffor the schematic ofFIG. 8A, for the most current board design, upon which it depends, is about 10 pF. As the clocking square wave is effectively integrated byC_ref92 and the capacitance ofANT100, two exponential signals appear atterminals 5104 and 6106 of the second comparator U1B, through theR_protect160 static protection resistors.R_protect160 resistors provide limiting resistance which enhances the inherent static protection of a comparitor input lines, particularly for the case ofpin 5104 ofU1B102. In the schematic shown inFIG. 8A, a typical value forR_protect160 might be 2 kΩ. One of the two exponential waveforms will be greater, depending upon the settings of theadjustable resistance R_trim96,C_ref92, andANT100. Thecomparator U1B102 resolves small differences, reporting logic levels at its output,pin 7118. As the waveforms may initially be set up, based on a capacitance atANT100 of a given amount. However, upon the intrusion of a hand, for example, into the detection field of theantenna ANT100, the capacitance ofANT100 is increased significantly and the prior relationship of the waveforms, which were set withANT100 with a lower capacitance, are switched over. Therefore, the logic level output atpin 7118 is changed and the D flip-flop108 state is changed via the input onpin 5 of the D flip-flop108.
• Thesecond comparator102 provides a digital quality signal to the D flip-flop108. The D flip-flop,U2A108, latches and holds the output of thecomparator U1B90. In this manner, the second comparator is really doing analog-to-digital conversion. A suitable D flip-flop is a Motorola 14013.
• The presence, and then the absence, of a hand can be used to start a motorized mechanism on a paper towel dispenser, for example. An embodiment of the proximity detector uses a single wire or a combination of wire and copper foil tape that is shaped to form a detection field. This system is very tolerant of non-conductive items, such as paper towels, placed in the field. A hand is conductive and attached to a much larger conductor to free space. Bringing a hand near the antenna serves to increase the antenna's apparent capacitance to free space, forcing detection.
• The shape and placement of the proximity detector's antenna (FIG. 8A, 100) turns out to be of some importance in making the proximity sensor work correctly. Experimentation showed that a suitable location was toward the lower front of the dispenser unit. The antenna (FIG. 8A, 100) was run about two-thirds the length of the dispensing unit, in a modular, replaceable unit above the removable dispensing shelf62 (FIG. 3). This modular unit would be denoted onFIG. 3 as120.
• A detection by the proximity detection circuit (FIG. 8A) in themodule120 sets up a motor control flip flop so that the removal of the hand will trigger the start of the motor cycle. The end of the cycle is detected by means of a limit switch which, when closed, causes a reset of the flip-flop and stops the motor. A cycle may also be initiated by closing a manual switch.
• A wide range of sensitivity can be obtained by varying the geometry of the antenna and coordinating the reference capacitor. Small antennae have short ranges suitable for non-contact pushbuttons. A large antenna could be disposed as a doorway-sized people detector. Another factor in sensitivity is the element applied as R_trim. IfR_trim96 is replaced by an adjustable inductor, the exponential signals become resonant signals with phase characteristics very strongly influenced by capacitive changes. Accordingly, trimming with inductors may be used to increase range and sensitivity. Finally, circuitry may be added to theantenna100 to improve range and directionality. As a class, these circuits are termed “guards” or “guarding electrodes,” old in the art, a type of shield driven at equal potential to the antenna. Equal potential insures no charge exchange, effectively blinding the guarded area of the antenna rendering it directional.
• The antenna design and trimming arrangement for the paper towel dispenser application is chosen for adequate range and minimum cost. The advantages of using a guarded antenna and an adjustable inductor are that the sensing unit to be made smaller.
• From a safety standpoint, the circuit is designed so that a detection will hold the motor control flip-flop in reset, thereby stopping the mechanism. The cycle can then begin again after detection ends.
• The dispenser has additional switches on thecontrol module54.FIG. 3 shows a “length-of-towel-to-dispense-at-one-time” (‘length”)switch134. Thisswitch134, is important in controlling how long a length of paper towel is dispensed, for each dispensation of towel. It is an important setting for the owner of the dispenser on a day-to-day basis in determining cost (to the owner) versus the comfort (to the user) of getting a large piece of paper towel at one time.
• A somewhat similarsecond switch136 is “time-delay-before-can-activate-the-dispensing-of another-paper-towel” (“time-delay”)switch136. The longer the time delay is set, the less likely a user will wait for many multiple towels to dispense. This tends to save costs to the owner. Shortening the delay tends to be more comfortable to a user.
• Athird switch138 is the sensitivity setting for the detection circuit. This sensitivity setting varies the resistance of R_trim96 (FIG. 8A). Once an effective antenna100 (FIG. 8A) configuration is set up, the distance from the dispenser may be varied. Typical actual use may require a sensitivity distance out to one or two inches, rather than four or six inches. This is to avoid unwanted dispensing of paper towel. In a hospital setting, or physician's office, the sensitivity setting might be made fairly low so as to avoid unwanted paper towel dispensing. At a particular work location, on the other hand, the sensitivity might be set fairly high, so that paper towel will be dispensed very easily.
• While it is well known in the art how to make these switches according to the desired functionality, this switch triad may increase the usefulness of the embodiment of this invention. The system, as shown in the embodiment herein, has properties of lowering costs, improving hygiene, improving ease of operation and ease of maintenance. This embodiment of the invention is designed to consume low power, compatible with a battery or battery pack operation. In this embodiment, a 6 volt DC supply is utilized. A battery eliminator may be use for continuous operation in a fixed location. There is a passive battery supply monitor that will turn on an LED indicator if the input voltage falls below a specified voltage.
• The most spectacular example of a build-up of static electric charge caused by mechanical separation of charge is the giant thunderstorm, with violent displays of lightning and the associated thunder. A more quiet but more pernicious static buildup problem is that associated with the destruction of electronic integrated circuit chips by unwanted static discharge to susceptible circuit leads. A common occurrence of the discharge of a mechanically-caused static charge buildup happens when a person becomes charged-up walking on a rug on a dry, typically cold, day and has an unpleasant but non-injurious experience of discharging that charge by contacting a grounded object.
• A similar situation occurs on a paper towel dispenser. Here, however, the separation of charge tends to be caused as a paper towel is separated from the main roll by being ripped-off along a guide bar, or a smooth or serrated blade. Some mechanical charge separation may also occur from the action of the paper towel web sliding along rib-structures and rollers of the dispenser. In many places where a paper towel dispenser is placed there is no, or no convenient access, to a ground wire or conduit of a 110V or 220 V electrical supply system or grounding rods or other ground-to-earth conductor.
• Consequently, the approach of this invention is used instead. To ground static electricity buildup on a paper towel dispenser, a high conductivity grounding wire connects internal components of the dispenser that are subject to accumulating static electric charge. The high conductivity grounding wire connects to an electrical mechanical contact on the outside of the dispenser. A metal contact between the high conductivity pathway, and for example, the wall against which the dispenser is mounted, provides an electrical pathway for the dissipation of the static electrical build up on the dispenser to a local electrical ground.
• The first step is to provide a low impedance pathway for collecting the static electric charge on the dispenser and bringing it to a wall contact.FIG. 10A shows a side of apaper towel dispenser2002 with anaccess hole2004 for the grounding wire (not shown) and shows a moldedrib2006 which prevents the low impedance grounding wire (not shown) from contacting an idler gear. The idler gear is not shown. Thisrib2006 may be molded into the structure. The rib helps to route the grounding wire out of the way of a potentially interfering mechanism. Thegrounding wire2016 may be seen inFIG. 11B. The access hole provides a convenient entrance so as to allow the routing of the low impedance grounding wire to the rear wall contact.
• Features of the chassis structure provide an approach to securing both the grounding wire2016 (FIGS. 11B, 11C, 14) to the rear wall contact2020 (FIGS. 11C, 12, 13B) and securing themetal wall contact2020 to the chassis of the dispenser. For the wall contact (not shown) there is a screw2008 (FIG. 10C) and ribs2010 (FIG. 10C) for attaching the wall contact to the chassis. This is seen inFIG. 10B and in a different view fromFIG. 10C. The wall contact may be screwed to the chassis and the grounding wire secured to the wall contact with the same screw.
• Since the nib rollers tend to pick up the initial static electric charge, the grounding wire is run from the nib rollers to the wall contact. ThusFIG. 11A shows thegear cover2012 with arib2014 molded into it, which holds the spring clip2018 (FIGS. 11C, 12, 13B) in place. Keeping the grounding wire in a relatively straight line from the charge collection near the charge generation source allows a minimum length for the grounding wire2016 (FIGS. 11B, 11C).
• The actual contacting is of thegrounding wire2016 to aspring clip2018, by a spring clip attachment means (2026,FIG. 11C). The spring has a spring clip means as part of its structure.FIG. 11B shows thegrounding wire2016 and its connection to the spring clip2018 (FIGS. 11C, 12, 13B). A compression spring2019 (FIG. 15) contacts the metal nib roller shaft (2022,FIG. 14) by spring pressure, providing a mechanical and electrical contact. The static electricity accumulated on the nib rollers may transfer from the nib rollers to the metal nib roller shaft (2022,FIGS. 11B, 11C, 14). Then the static electricity may transfer through thespring clip2018 to thegrounding wire2016. Theground wire2016 is held by a spring clip means (2026,FIG. 14) to the spring clip2018 (FIGS. 11C, 12, 13B).
• FIG. 12 is a perspective view showing the wall contactspring grounding clip2020 and theground wire2016, which is partially hidden as it enters theaccess hole2004. The wall contactspring grounding clip2020 is on the rear side of the paper towel dispenser. It is connected to thegrounding wire2016, which is hidden by part of the structure of thedispenser2002. InFIG. 11C, toward the front side of thedispenser2002, thegrounding wire2016 is connected to thespring clip2018 that electrically and mechanically connects to thenib roller shaft2022 by spring pressure. AsFIG. 11C shows, the grounding contact runs from the nib roller (not shown) to the metalnib roller shaft2022 through a spring clip2018 (FIGS. 11C, 12, 13B). The ground contact continues through thegrounding wire2016 to the wall contactspring grounding clip2020. When thedispenser2002 is mounted on a wall, the wall contactspring grounding clip2020, acting as a partially compressed spring, presses against the wall to maintain a mechanical pressure contact which provides an electrical conduction path to the wall from the static build up areas on thetowel dispenser2002.
• FIG. 12 shows the pathway of thegrounding wire2016 from where it enters theaccess hole2004 toward the interior of thedispenser2002. Thegrounding wire2016 continues until it contacts the wall contactspring grounding clip2020. Theground wire2016 is attached to the wall contactspring grounding clip2020 by screw, bolt, soldering or other common methods of affixing a grounding wire to a metal contact which serves to complete a grounding path.
• It may be appreciated that a dispenser may be made of alternative materials or combinations of materials. For example, in the case where the rear chassis of the dispenser is made of galvanized steel or stainless steel, the chassis itself may be formed with one or more integral spring wall contacts. The grounding wire, in these embodiments, may be attached by a means including, but not limited to, screw, bolt, soldering, brazing, or welding. In another embodiment, the rear chassis may be of a plastic, but having metal straps. These metal straps may also be formed with one or more integral spring contacts. The grounding wire may then be attached to the metal straps. Again, the dispenser may be made completely of metal, for example, stainless steel. In this embodiment, the grounding wire system may be used, or, the electrical grounding path may be from the spring contact, which presses against the nib roller, to the metal paper towel dispenser casing to the rear wall, by way of one or more integral spring wall contacts.
• FIG. 13A shows theopening2026 in therear cover2028 for the wall contact spring grounding clip. The placement of the opening tends to be determined by keeping a shortest grounding wire, together with structural manufacturing considerations for the paper towel dispenser chassis.
• FIG. 13B shows the wall contactspring grounding clip2020 in place, ready for the papertowel dispensing unit2002 to be mounted in such a way as to press that wall contact spring grounding clip against the wall and maintain a good mechanical and electrical contact.
• FIGS. 14 and 15 illustrate thedispenser2002 with the front cover removed, shows further details of the connection from the nib roller (not shown) to the metalnib roller shaft2022 and then through aspring clip2018 which connects to the nib roller compression spring (not shown) and a spring clip attachment means2026 connected to thegrounding wire2016 and to the wall contact spring grounding (not shown) clip to the wall (not shown).
• Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims (19)

What is claimed is:

1. A dispenser for dispensing flexible sheet material, comprising:

a support adapted to hold a roll of flexible sheet material;

a cover adapted to move from a closed position covering the roll to an open position allowing access to the roll;

a motor driven feed mechanism adapted to receive and dispense flexible sheet material from the roll;

an electronic proximity sensor adapted to detect the presence of a user;

an electronic control unit in operable communication with the electronic proximity sensor and the motor driven feed mechanism and adapted to control dispensation of the flexible sheet material, the electronic control unit comprising a jog off-on switch adapted to provide movement of the motor driven feed mechanism upon depression of the jog off-on switch.

2. The dispenser ofclaim 1, wherein the jog off-on switch is adapted to provide temporary movement of the motor driven feed mechanism while the jog off-on switch is maintained in a depressed state.

3. The dispenser ofclaim 1, wherein the jog off-on switch is adapted to allow the flexible sheet material to be threaded through the motor driven feed mechanism while the jog off-on switch is maintained in a depressed state.

4. The dispenser ofclaim 1, wherein the cover covers the jog off-on switch when the cover is in the closed position, and wherein the cover allows access to the jog off-on switch when the cover is in the open position.

5. The dispenser ofclaim 1, wherein the electronic control unit further comprises an on-off switch adapted to move from an on position when the cover is in the closed position to an off position when the cover is in the open position.

6. The dispenser ofclaim 1, wherein the electronic control unit further comprises a length switch adapted to control a length of the flexible sheet material being dispensed by the motor driven feed mechanism.

7. The dispenser ofclaim 6, wherein the cover covers the length switch when the cover is in the closed position, and wherein the cover allows access to the length switch when the cover is in the open position.

8. The dispenser ofclaim 1, wherein the electronic control unit further comprises a time delay switch adapted to set a time delay between successive dispense cycles of the flexible sheet material being dispensed by the motor driven feed mechanism.

9. The dispenser ofclaim 8, wherein the cover covers the time delay switch when the cover is in the closed position, and wherein the cover allows access to the time delay switch when the cover is in the open position.

10. The dispenser ofclaim 1, wherein the electronic control unit further comprises a sensitivity switch adapted to control a sensitivity of the electronic proximity sensor.

11. The dispenser ofclaim 10, wherein the cover covers the sensitivity switch when the cover is in the closed position, and wherein the cover allows access to the sensitivity switch when the cover is in the open position.

12. A dispenser for dispensing flexible sheet material, comprising:

a support adapted to hold a roll of flexible sheet material;

a motor driven feed mechanism adapted to receive and dispense flexible sheet material from the roll;

an electronic proximity sensor adapted to detect the presence of a user;

an electronic control unit in operable communication with the electronic proximity sensor and the motor driven feed mechanism and adapted to control dispensation of the flexible sheet material, the electronic control unit comprising a sensitivity switch adapted to control a sensitivity of the electronic proximity sensor, and a jog off-on switch adapted to provide movement of the motor driven feed mechanism upon depression of the jog off-on switch; and

a cover adapted to move from a closed position to an open position, wherein the cover covers the sensitivity switch when the cover is in the closed position, and wherein the cover allows access to the sensitivity switch when the cover is in the open position.

13. The dispenser ofclaim 12, wherein the electronic control unit further comprises a length switch adapted to control a length of the flexible sheet material being dispensed by the motor driven feed mechanism.

14. The dispenser ofclaim 13, wherein the cover covers the length switch when the cover is in the closed position, and wherein the cover allows access to the length switch when the cover is in the open position.

15. The dispenser ofclaim 12, wherein the electronic control unit further comprises a time delay switch adapted to set a time delay between successive dispense cycles of the flexible sheet material being dispensed by the motor driven feed mechanism.

16. The dispenser ofclaim 15, wherein the cover covers the time delay switch when the cover is in the closed position, and wherein the cover allows access to the time delay switch when the cover is in the open position.

17. The dispenser ofclaim 12, wherein the jog off-on switch is adapted to provide temporary movement of the motor driven feed mechanism while the jog off-on switch is maintained in a depressed state.

18. The dispenser ofclaim 12, wherein the jog off-on switch is adapted to allow the flexible sheet material to be threaded through the motor driven feed mechanism while the jog off-on switch is maintained in a depressed state.

19. The dispenser ofclaim 12, wherein the cover covers the jog off-on switch when the cover is in the closed position, and wherein the cover allows access to the jog off-on switch when the cover is in the open position.

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