Abstract:
A dispenser for rolled absorbent web material is disclosed. A carriage is rotatable between at least two orientations. The carriage includes a first roll holder, which holds a first roll of absorbent web material in a primary position when the carriage is in a first orientation and in a secondary position when the carriage is in a second orientation, and a second roll holder, which holds a second roll of absorbent web material in the secondary position when the carriage is in the first orientation and in the primary position when the carriage is in the second orientation. A roll sensor senses the amount of absorbent web material remaining on the roll in the primary position. A feed mechanism dispenses absorbent web material from at least one of the rolls. A transfer mechanism feeds absorbent web material from the roll in the secondary position into the feed mechanism when the absorbent web material on the roll in the primary position is nearly depleted.

Description:
PRIORITY  
       [0001]     Priority is claimed as a continuation to U.S. patent application Ser. No. 11/052,496, filed Feb. 3, 2005, which is a divisional of U.S. Pat. No. 6,871,815, filed Sep. 27, 2001, which is a continuation-in-part of U.S. Pat. No. 6,592,067, filed Feb. 9, 2001, the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to the field of dispensers which dispense absorbent web material stored in a roll.  
         [0004]     2. Background of the Invention  
         [0005]     As is readily apparent, a long-standing problem is to keep paper towels 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.  
         [0006]     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.  
         [0007]     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.  
         [0008]     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.  
         [0009]     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.  
         [0010]     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.  
         [0011]     The capacity (C) is defined as the charge (Q) stored on separated conductors with a voltage (V) difference between the conductors: 
 
 C=Q/N.  
 
         [0012]     For two infinite conductive planes with a charge per unit area of σ, a separation of d, with a dielectric constant ε of the material between the infinite conductors, the capacitance of an area A is given by: 
 
 C=εAσ/d  
 
         [0013]     Thus, where part of the separating material has a dielectric constant ε 1  and part of the material has the dielectric constant ε 2 , the net capacity is: 
 
 C=ε   1   A   1   σ/d+ε   2   A   2   σ/d  
 
         [0014]     The human body is about 70% water. The dielectric constant of water is 7.18×10 −10  farads/meter compared to the dielectric constant of air (STP): 8.85×10 −12  farads/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 −4 .  
         [0015]     About 10 −2  is contributed by the difference in the dielectric constants and about 10 −2  is contributed by the “area” difference.  
         [0016]     Besides Riechmann (1973), other circuits have been used for, or could be used for proximity sensing.  
         [0017]     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.  
         [0018]     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.  
         [0019]     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.  
         [0020]     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.  
         [0021]     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.  
         [0022]     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.  
         [0023]     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&#39;t reach an earth ground as the wall material does not conduct electricity well.  
         [0024]     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  
       [0025]     The invention comprises to a carousel-based dispensing system for absorbent web material stored in a roll, in particular, which acts to minimize actual wastage of such absorbent web material. The invention comprises a carriage which is rotatable between at least a first orientation and a second orientation. The carriage includes two roll holders, each for holding a roll of absorbent web material. The first roll holder is adapted to hold the first roll of absorbent web material in a primary position when the carriage is in the first orientation and in a secondary position when the carriage is in the second orientation. The second roll holder is adapted to hold the second roll of absorbent web material in the secondary position when the carriage is in the first orientation and in the primary position when the carriage is in the second orientation. A roll sensor senses the amount of absorbent web material remaining on the roll held in the primary position. A feed mechanism dispenses absorbent web material from the roll held in the primary position. A transfer mechanism is adapted to feed absorbent web material from the roll held in the secondary position into the feed mechanism when the roll sensor senses that the absorbent web material on the roll held in the primary position is depleted to less than a predetermined diameter. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]     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:  
         [0027]      FIG. 1  is a side elevation of the dispenser with the cover closed, with no internal mechanisms visible;  
         [0028]      FIG. 2  is a perspective view of the dispenser with the cover closed, with no internal mechanisms visible;  
         [0029]      FIG. 3  shows a view of the carousel support, the locking bar and the transfer bar;  
         [0030]      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;  
         [0031]      FIG. 4B  is a side view of the locking bar showing the placement of the compression springs;  
         [0032]      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;  
         [0033]      FIG. 5  is a perspective, exploded view of the carousel assembly;  
         [0034]      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;  
         [0035]      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;  
         [0036]      FIG. 7A  is a side elevation view of the carousel ready for loading when the main roll reaches a specific diameter;  
         [0037]      FIG. 7B  is a side elevation view of the locking bar being pulled forwardly to allow the carousel to rotate  1800 , placing the main roll in the previous stub roll position;  
         [0038]      FIG. 7C  shows the location of the extension springs which tend to maintain the transfer bar legs in contact with the stub roll;  
         [0039]      FIG. 7D  shows the cleanable floor of the dispenser;  
         [0040]      FIG. 8A  shows a schematic of the proximity circuit;  
         [0041]      FIG. 8B  (prior art) shows the schematic for the National Semiconductor dual comparator LM393;  
         [0042]      FIG. 9A  shows the square wave output at U1A, pin  1 ;  
         [0043]      FIG. 9B  shows the RC exponential waveforms at pins  5 ; and  
         [0044]      FIG. 9C  shows the RC exponential waveforms at pin  6 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0045]     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.  
         [0046]     An embodiment of the invention comprises a carousel-based dispensing system with a transfer bar for dispensing absorbent web material stored on a roll. In the embodiment shown, the absorbent web material is paper which is advantageously separated into paper towels at the time of dispensation. The embodiment shown and described helps 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.  
         [0047]     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.  
         [0048]     A side view,  FIG. 1 , of the dispenser  20  with the cover  22  in place shows an upper circular bulge  24 , 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 the dispenser  20  with cover  22  in place and the circular (cylindrical) bulge  24 , together with the sunrise-like setback  26  on the cover  22 , which tends to visually guide a hand toward the pseudo- button  28 , leading to activation of a proximity sensor (not shown). A light emitting diode (LED)  130  is located centrally to the pseudo-button  28 . The LED  130  ( FIG. 3 ) serves as an indication that the dispenser  20  is on, and dispensing towel. The LED  130  may be off while the dispenser is not dispensing. Alternatively, the LED  130  may be lit (on), and when the dispenser  20  is operating, the LED  130  might flash. The LED  130  might show green when the dispenser  20  is ready to dispense, and flashing green, or orange, when the dispenser  20  is operating to dispense. Any similar combination may be used. The least power consumption occurs when the LED  130  only lights during a dispensing duty cycle. The sunrise-like setback  26  ( FIG. 2 ) allows a hand to come more closely to the proximity sensor (not shown).  
         [0049]      FIG. 3  shows the main elements of the carousel assembly  30 . The carousel arms  32  have friction reducing rotating paper towel roll hubs  34 , which are disposed into the holes of a paper towel roll ( 66 ,  68 ,  FIG. 4A ). The locking bar  36  serves to lock and to release the carousel for rotation about its axis  38 . The locking bar  36  rides on one of the corresponding bars  40 . The two corresponding bars  40  serve as support bars. Cross-members  42  serve as stiffeners for the carousel assembly  30 , and also serve as paper guides for the paper to be drawn over and down to the feed roller  50  and out the dispenser  20 . These cross members are attached in a rigid fashion to the corresponding bars  40  and in this embodiment do not rotate.  
         [0050]     The legs  46  of the transfer bar  44  do not rest against the friction reducing rotating paper towel roll hubs  34  when there is no stub roll  68  present but are disposed inward of the roll hubs  34 . The bar part  88  of the transfer bar  44  will rest against a structure of the dispenser, for example, the top of modular electronics unit  132 , when no stub roll  68  is present. The bar part  88  of the transfer bar  44  acts to bring the tail of a new main roll of paper towel  66  ( FIG. 4A ) down to the feed roller  50  which includes intermediate bosses  146  ( FIG. 3 ) and shaft  144 . The carousel assembly is disposed within the fixed casing  48 . The cover is not shown.  
         [0051]     Feed roller  50  serves to feed the paper towels  66 ,  68  ( FIG. 4A ) being dispensed onto the curved dispensing ribs  52 . The curved dispensing ribs  52  are curved and have a low area of contact with the paper towel dispensed (not shown). If the dispenser  20  gets wet, the curved dispensing ribs  52  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.  
         [0052]     The feed roller  50  is typically as wide as the paper roll, and includes drive rollers  142  and intermediate bosses  146  on the drive shaft  144 . The working drive rollers or drive bosses  142  ( FIG. 3 ) are typically an inch or less in width, with intermediate bosses  146  ( FIG. 3 ) located between them. Intermediate bosses  146  are slightly less in diameter than the drive rollers or drive bosses  142 , having a diameter 0.015 to 0.045 inches less than the drive rollers or drive bosses  142 . In this embodiment, the diameter of the intermediate bosses  146  is 0.030 inches less than the drive roller  142 . This configuration of drive rollers or drive bosses  142  and intermediate bosses  146  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 the feed roller  50 .  
         [0053]     A control unit  54  operates a motor  56 . Batteries  58  supply power to the motor  56 . A motor  56  may be positioned next to the batteries  58 . A light  60 , for example, a light-emitting diode (LED), may be incorporated into a low battery warning such that the light  60  turns on when the battery voltage is lower than a predetermined level.  
         [0054]     The cover  22  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 battery low light  60  may easily be seen. Otherwise an individual window on an opaque cover  22  would need to be provided to view the low battery light  60 . Another approach might be to lead out the light by way of a fiber optic light pipe to a transparent window in the cover  22 .  
         [0055]     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 the cover  22  and the casing  48 . The dispensing shelf  62  is a modular component, which is removable from the dispenser  20 . In the waterproof version of the dispenser  20 , the dispensing shelf  62  with the molded turning ribs  52  is removed. By removing the modular component, dispensing shelf  62 , there is less likelihood of water being diverted into the dispenser  20  by the dispensing shelf  62 , acting as a funnel or chute should a water hose or spray be directed at the dispenser  20 , 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. The dispenser  20  has an on-off switch which goes to an off state when the cover  22  is pivoted downwardly. The actual switch is located on the lower face of the module  54  and is not shown.  
         [0056]     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.