Abstract:
A paper towel dispenser which provides for hands free, automatic feeding of the first sheet of a primary web roll, such as a paper towel roll, into a feed mechanism when its cover is closed. The dispenser also automatically transfers its web feed supply from a primary roll to a reserve roll upon the exhaustion of the primary roll. The present invention eliminates the need for an attendant to thread the leading edge of a primary or reserve roll into the feed mechanism of the dispenser. The dispenser also eliminates wasted paper because it does not begin to feed the reserve roll until the primary roll has expired. The dispenser can include either a manual feed mechanism or a powered feed mechanism. The dispenser relies on a sensor for determining when a portion of the web is absent from a side of the feed mechanism proximate a web discharge opening. When such an absence is sensed, an automatic, powered web transfer mechanism contacts the web located in front of the feed mechanism and positions it between the rollers of the feed mechanism. The transfer mechanism includes a web transfer member and a motor for driving the transfer member in the direction of the feed mechanism. The dispenser also includes a retraction mechanism for returning the transfer bar to a rest position after the web has been introduced into the feed mechanism.

Description:
The present invention relates generally to a flexible web dispenser that includes a powered, hands-free web transfer mechanism and, more particularly, to a paper towel dispenser having a automatic, power transfer mechanism for introducing a primary towel roll into a towel feeding mechanism and for transferring the feed supply of a paper towel dispenser from a primary roll to a reserve roll upon the sensed exhaustion of the primary roll. 
     BACKGROUND OF THE INVENTION 
     Industrial dispensers are widely used in public lavatories for dispensing paper towels to users. These dispensers can be designed to dispense either rolled paper towel sheets or folded paper towels arranged in a linear bundle. Rolled paper towels are continuous webs of paper toweling that are wound around a central core and, upon dispensing, are separated into and delivered as individual lengths of material. Folded towels are individual lengths of a paper web that have been pre-cut, folded into a predetermined configuration and arranged in a vertical or horizontal bundle for being individually dispensed. 
     Rolled paper towel dispensers typically include a user operated crank or lever that drives a feed mechanism to dispense the paper towels. However, as can be appreciated, these dispensers can also include an automatically operated feed mechanism as disclosed in copending U.S. Pat. applications Ser. Nos. 09/081,637 and 09/453,794 to Formon et al. titled “Paper Towel Dispenser” which are hereby expressly incorporated by reference. The automatic feed mechanism includes a drive roller and a pressure roller, also known as a pinch roller, which form a nip. When the rolled paper runs out in a conventional roll dispenser, an attendant must replace the roll(s) and manually insert the leading edge of the rolled towel into the nip. This can require complex towel threading and complicated loading sequences. After the attendant has placed the leading edge of the roll into the nip, the feed mechanism is operated in order to advance the leading edge through the feed mechanism, unwind the paper towel from the roll core and deliver the paper towel to the user. The feed mechanism can be either manual or automatic. 
     In contrast to folded paper towel dispensers, there is no economical way to replenish a roll towel dispenser when only a portion of the reserve roll, or “stub” roll, remains within the dispenser. In some prior art dispensers, a new roll must be substituted for the stub roll, thereby wasting whatever paper remains on the stub. This can result in increased operational costs as a significant amount of paper maybe be wasted in facilities with many dispensers. To overcome the problem of stub roll waste, roll dispensers have been designed to dispense two rolls of web material sequentially such that upon depletion of a primary roll, feeding from a reserve roll is commenced. 
     Prior art systems have included different types of transfer systems to change between the primary and reserve rolls. One such transfer system uses the diameter of the primary roll as a gauge for activating a transfer mechanism when it reaches a predetermined size. U.S. Pat. No. 5,294,192 to Omdoll et al. discloses a system which includes a mechanical sensor that detects the amount of paper towel on a primary roll. When the primary roll is depleted to a predetermined level, the sensor mechanically activates a transfer apparatus which drives the free end of the reserve roll into the nip of a dispenser using a transfer bar. However, since the sensor detects the size of the primary roll, not the end of the rolled web, the reserve web may begin dispensing prior to the complete exhaustion of the primary roll. Thus, for a period of time, paper towel is simultaneously dispensed from both rolls. This results in wasted paper towels. Additionally, these types of mechanical sensors can become stuck within the dispenser and fail to operate. 
     To overcome these disadvantages, the systems of U.S. Pat. No. 4,165,138 to Hedge et al., U.S. Pat. No.4,611,768 to Voss, et al., and U.S. Pat. No. 4,378,912 to Perrin et al. provide a transfer mechanism which is based on the feed rolls themselves. These systems utilize a transfer mechanism which senses the absence or presence of paper from around a feed roll. In one system, this is accomplished by a sensing finger which rides along the top surface of the web material and then drops down into a groove in the feed roll which is exposed when the trailing end of the primary web has been unwound from the roll. In response to the sensing finger moving into the groove, the reserve web is introduced into the feed nip between the drive roller and the pressure roller, and the dispenser begins to feed the reserve roll to the user. This type of transfer mechanism generally eliminates the false transfers associated with tension responsive systems and reduces the amount of double sheet dispensing which occurs in diameter sensing transfer systems. The use of sensing fingers on the web material, however, produces extra friction which can inadvertently tear the web. Moreover, the introduction of additional components to sense the absence of the web and transfer the reserve web to between the feed rollers creates opportunities for a transfer failure to occur. 
     The object of the present invention is to overcome the drawbacks of the prior art paper towel dispensers. 
     It is also an object of the present invention to provide a web dispenser that includes a powered web transfer mechanism which eliminates the need for an attendant to feed a leading edge of a rolled web into the nip. 
     It is further an object of the present invention to provide a web dispenser having a powered web transfer mechanism that automatically and reliably feeds a leading edge of a reserve roll into a nip. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a paper towel dispenser which provides hands free, automatic feeding of the first sheet of a primary web roll, such as a paper towel roll, into a feed mechanism when its cover is closed. The dispenser also automatically transfers its web feed supply from a primary roll to a reserve roll upon the exhaustion of the primary roll. The present invention eliminates the need for an attendant to thread the leading edge of a primary or reserve roll into the feed mechanism of the dispenser. The dispenser also eliminates wasted paper because it does not begin to feed the reserve roll until the primary roll has expired. 
     The dispenser includes a chassis having a web discharge opening and a feed mechanism for advancing the web to the web discharge opening. The dispenser can include either a manual feed mechanism or a powered feed mechanism. The dispenser also includes a sensor for determining when a portion of the web is absent from a side of the feed mechanism proximate the web discharge opening. When such an absence is sensed, an automatic, powered web transfer mechanism contacts the web located in front of the feed mechanism and positions it between the rollers of the feed mechanism. The transfer mechanism includes a web transfer member and a motor for driving the transfer member in the direction of the feed mechanism. The dispenser also includes a retraction mechanism for returning the transfer bar to a rest position after the web has been introduced into the feed mechanism. 
     A method of positioning a web in a feed mechanism of a dispenser according to the present invention includes the steps of positioning a leading edge of a web proximate a first side of the feed mechanism, sensing the absence of the web on a second side of the feed mechanism and activating a powered transfer drive mechanism in response to the sensed absence. The method further includes the steps of automatically advancing a transfer bar in the direction of the feed mechanism when the drive mechanism is activated, engaging the web with a plurality of web positioning members on the transfer bar and advancing the web into the feed mechanism. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a side view of a dispenser according to the present invention; 
     FIG. 2 is a side view of the dispenser with the cover and transfer bar in web loading positions; 
     FIG. 3 is a perspective view of the transfer mechanism according to the present invention; and 
     FIG. 4 is a side schematic view of the transfer mechanism and a portion of the feed mechanism according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 and 2 illustrate a paper towel dispenser  10  according to the present invention comprising a chassis  12  which includes a back panel  14 , side panels  16 , and a pivotal front cover  20  attached by a pin, hinge or other convenient attachment mechanism  20   a . Front cover  20  is opened and pivoted away from chassis  12  to a web loading position so that a primary roll  25  and a reserve roll  25  of a web  27  can be loaded into the dispenser  10 . In a preferred embodiment, each roll consists of a continuous web  27  of a paper towel wound upon a hollow, cylindrical core  38 ′. However, the dispenser  10  could dispense other flexible webs. The web  27  can include flat or folded sheet segments. In the preferred embodiment, the web  27  includes a series of spaced apart, transverse tear lines which subdivide the web into the sheet segments of a predetermined length. Rolls  25  are rotatably supported by a pair of arms  35  extending forwardly from back panel  14 . Each of the arms  35  includes an inwardly directed hub  35 ′ loosely received within the core  38 ′ of the rolls  25  to permit free rotation of the rolls  25 . However, other mounting arrangements could also be used. 
     A feed mechanism  37  is mounted within the housing defined by chassis  12  to dispense the web  27  in incremental sheet segments. The feed mechanism  37  can be either manually operated using a lever or other well known devices, or it can be operated using an automatically activated motor as discussed in the copending U.S. patent applications to Formon et al. that were previously incorporated by reference. In the preferred construction, feed mechanism  37  includes a feed (drive) roller  22  and a pressure roller  24  which cooperate to dispense the web  27 . Feed roller  22  and pressure roller  24  are mounted upon axles  45 ,  46 , respectively, rotatably supported by side panels  16 . The pressure roller  24  is preferably biased against the feed roller by a spring (not shown) to define a feed nip  47  for dispensing the web  27  through a discharge opening  48 . 
     When the dispenser  10  includes a powered feed mechanism  37 , the feed roller  22  is driven in a direction (i.e. clockwise as viewed in FIG. 1) by an electric motor  30  mounted within the dispenser and powered by batteries  58 . A worm gear secured to a drive shaft of motor  30  engages a drive gear secured to axle  45  and rotates feed roller  22 . When the paper web  27  is fed into the nip  47  as discussed below, the rotation of the feed roller  22  causes the web  27  to be advanced around feed roller  22 , and out through discharge opening  48 . A guide plate  87  is provided to direct the web  27  along the desired path. Low power requirements for motor  30  insure that the batteries  58  need only infrequent replacement. Other feed mechanisms having other roller and gear arrangements, or other power supplies, such as a step down AC to DC power supply, could also be used. 
     The web  27  is introduced into the feed mechanism  37  by power transfer system  50  which includes a transfer bar  51  pivotally mounted within the dispenser  10 . The powered transfer system  50  also includes a transfer drive system  60  which operatively connects the transfer bar  51  to an electric transfer motor  61  located within the dispenser chassis  12 . The drive system  60  imparts the rotary movement of the output shaft of the transfer motor  61  to the transfer bar  51  so that the transfer bar  51  and finger  52  rotate in the direction of the nip  47  and position the web  27  in the nip  47  when the motor  61  is operated. The electric motor  61  has low power requirements and, in a preferred embodiment, is powered by the same batteries  58  as electric motor  30 . Alternatively, the transfer motor  61  can be powered by a dedicated DC power supply or a step down AC to DC power supply. 
     As shown in FIG. 3, transfer bar  51  is an elongated member having a plurality of cross braces that provide rigidity. The transfer bar  51  extends between the side panels  16  of the chassis  12  and along the length of the nip  47 . It is contemplated that the nip  47  can extend a greater or lesser distance between the side panels  16  than the transfer bar  51 . The transfer bar  51  also includes cover engaging members  53  with rounded upper shoulders  54  that rest against the inside of the front cover  20  when the cover  20  is closed and the transfer bar  51  is at rest. The cover engaging members  53  can include any shape that support the transfer bar  51  on the front cover  20 . 
     A set of bearings  71  pivotally support the transfer bar  51  on a shaft  70  which extends between the side panels  16 . These bearings  71  permit the transfer bar  51  to rotate in a direction (counter clockwise in FIG. 1) about the shaft  70  when the cover  20  is pivoted to an open position so that the transfer bar  51  and cover  20  can both rotate to a web loading position in which they are conveniently out of the way of the attendant loading the dispenser as shown in FIG.  2 . The bearings  71  also permit the transfer bar to rotate about shaft  70  in the direction of the nip  47  (clockwise in FIG. 1) when the transfer mechanism  50  is activated, as discussed below. The transfer bar  51  can also be mounted to the chassis using hinges or other convenient attaching mechanisms which will allow it to pivot or move away from the nip so that the primary and/or secondary rolls of web  27  can be installed. In another preferred embodiment, the transfer bar  51  could experience both translational and arcuate movement when traveling from its rest position against cover  20  to its web loading position. The shaft  70  includes a groove  72  which engages an elongated member (not shown) secured within the dispenser. When engaged, the elongated member prevents the shaft  70  from translational motion when the transfer bar  51  rotates. Other well known ways of restraining (locking) the shaft  70  against translational motion can also be used. 
     The transfer bar  51  also includes a plurality of the rigid transfer fingers  52  spaced along its length for engaging the paper web  27  and positioning it in the nip  47  formed by the feed roller  22  and the pressure roller  24 . FIGS. 3 and 4 show the transfer bar  51  including fingers  52 . The number of transfer fingers  52  can depend on the length of the transfer bar  51  or the strength of the paper web. The longer the transfer bar  51  or the weaker the paper web  27 , the more transfer fingers  52  that will be spaced along the transfer bar  51 . As shown in FIG. 4, the fingers  52  extend away from the transfer bar in the direction of the nip  47 . These fingers  52  include paper contacting ends  57  which have a rounded forward edge that is directed at the nip  47  when the transfer bar  51  is in its rest position. The forward edge of each finger  52  is rounded and sized so that it will engage and position the paper web  27  between the rollers  22 ,  24  without tearing it. 
     The motor  61  is activated by a sensor  28  located within the dispenser  10  for detecting the presence or absence of the web  27  at the discharge side of the feed mechanism  37 . The sensor  28  is coupled with a microprocessor  29  or the like so that the motor  61  is activated immediately after the trailing edge of a roll  25  of the web  27  passes the sensor  28  or when no web  27  is sensed. The sensor  28  may be any suitable mechanism, for example, a limit switch (not shown), an acoustical sensor (not shown) or an optical sensor that includes an emitter and a photo diode that is occulated by the web  27 . In the latter example, the emitter may be pulsed and the output of the photodiode high-pass filtered. In this way, the effect of ambient light on the photo diode is compensated. This may be implemented directly through the microprocessor  29 . 
     The transfer drive system  60  includes an output gear  62  which is connected to the output shaft of the transfer motor  61  and a transfer gear  65  which meshes with the output gear  62  so that the transfer gear  65  will rotate when the transfer motor  61  is operated. As seen in FIG. 4, the transfer gear  65  forms a portion of a circle. A plurality of gear teeth are positioned along the outer circumference of transfer gear  65 . These teeth mesh with the teeth of output gear  62  and drive the transfer gear  65  in a clockwise direction (as shown in FIG. 4) when the transfer motor  61  is operated. The gear teeth extend along the outer circumference of the transfer gear  65  which is equal to or greater than the length of the arc that the transfer bar  51  sweeps when it moves from its rest position to a web insertion position where it engages the web and introduces it into the nip  47 . The distance the teeth extend along the transfer gear  65  can be changed to meet the needs of a particular dispenser, so long as they extend over a distance which is sufficient to move the transfer bar  51  between its rest position and its final, web insertion position. 
     A transfer link  63  extends between the transfer gear  65  and the transfer bar  51  for imparting the movement of the transfer gear  65  to the transfer bar  51 . The transfer link  63  is formed of a rigid material, such as a plastic, so that the movement of the transfer gear  65  will be efficiently transferred to the transfer bar  51 . The transfer link  63  is secured at a first end  67  to the transfer gear  65  by a linkage plate  64 . As the transfer gear  65  is driven in a clockwise direction by output gear  62 , as shown in FIG. 4, the linkage plate  64  is rotated and the transfer link  63  moves linearly and arcuately upwardly in the direction of the transfer gear  65 . This is in part due to the position of link  63  on transfer gear  65 . At a second end  68 , the transfer link  63  includes an open bottom hook  69  that engages a post  66  extending outwardly from one side of the transfer bar  51  in the direction of one of the side panels  16 . As the transfer link  63  moves linearly and arcuately in response to the movement of the transfer gear  65 , the hook  69  engages post  66  and causes it to move along a path which extends between the front and rear of the dispenser. As a result, the transfer fingers  52  begin to move in the direction of the nip  47 . After the transfer gear  65  has been rotated, the amount of rotation can vary depending on the location of fingers  52  relative to nip  47 , the transfer bar  51  is positioned in front of nip  47  so that the transfer fingers  52  contact the web  27  and position it within the nip  47  as the transfer gear  65  continues to rotate along its toothed portion. Pressure between the fingers  52  and the rollers  22 ,  24  can stop the transfer gear  65  from rotating. 
     As seen in FIG. 4, the bottom of the hook  69  is open and the front, inner edge  80  of the hook  69  is beveled so that the post  66  can move in and out of the hook  69  depending on the position of the front cover  20 , the transfer bar  51  and the transfer link  63 . The edge  80  includes an upper, pointed portion  86  for engaging the rod  66  when the transfer link  63  moves toward the rear of the dispenser  10  in response to the rotation of transfer gear  65 . When the cover  20  is opened, the post  66  falls out of the hook  69  through the open bottom and the transfer bar  51  rotates downwardly, as discussed below. As the cover  20  is closed, the post  66  moves into the open, lower side of hook  69  by passing along the beveled edge  80 . The inner, open area  81  of the hook  69  is also larger than the diameter of the post  66  so that the post  66  has adequate clearance to drop out of the hook  69  and away from the transfer link  63  when the cover is opened and return into the hook  69  as the cover is closed. The inside of hook  69  proximate the transfer link  63  includes a recessed portion  88  for receiving post  66  and returning it with transfer bar  51  to their rest positions. It is also contemplated that the transfer mechanism can operate with a dispenser which has a cover that pivots to its open position along a top edge. In such a dispenser, the transfer system  50  would be appropriately located within the chassis  12 . 
     The transfer mechanism  50  can also include a return mechanism for returning the transfer bar  51  to its rest position. In a preferred embodiment, this mechanism comprises spring retaining member  84  which secures a first end of a coil spring  85  or other type of resilient or gear return member to the transfer gear  65 . The second end of the coil spring  85  is secured to the chassis  12  or another part of the dispenser. The transfer gear  65  could also include a pair of spring retaining members  84  and a pair of coil springs  85 , each attached to one of the retaining members  84 . When the transfer bar  51  is at rest, the coil spring(s)  85  is also at rest. However, when the transfer gear  65  rotates in response to the movement of gear  62 , the coil spring  85  is extended, the transfer link  63  moves toward the rear of the dispenser and the transfer bar  51  rotates in the direction of the nip  47 . After the web  27  has been transferred to the nip  47 , the coil spring  85  returns to its rest state while returning the transfer gear  63  to its rest position—the same position it was in before the transfer motor  61  was activated. During this return stroke, the recessed portion  88  engages post  66  and returns it and transfer bar  51  to their rest positions. When such a return mechanism is used with transfer gear  65 , the output shaft of the transfer motor  61  free wheels in its reverse direction. 
     In another preferred embodiment, the return mechanism can include a reverse drive mechanism of motor  61 . This reverse drive mechanism powers the transfer bar  51 , the transfer link  63  and the transfer gear  65  to their rest positions after the web  27  has been introduced and fed through the nip  47 . In this embodiment, the coil springs  85  are not needed because the motor  61  performs their operation. However, they may be used to assist the motor  61  when operating in its reverse direction, thereby reducing the amount of power consumed by the reverse drive mechanism. 
     The transfer system  50  eliminates the need for an attendant to go through the complicated process of feeding or threading the web  27  into the nip  47 . The operation of this dispenser  10  will be described with reference to a paper web, however, other dispensable webs could be used. When a dispenser according to the present invention is new or is otherwise without paper, the attendant must open the front cover  20  and load at least one paper towel roll. If the dispenser is designed to accommodate a primary roll and a reserve roll, the attendant will normally load both rolls within the dispenser while the cover  20  is open. When loading the paper, the attendant unlocks the dispenser and rotates the cover downwardly away from the chassis  12  to its web loading position as shown in FIG.  2 . However, as discussed above, the cover  20  can also be rotated in an upward direction. As the cover  20  is opened and pivoted to its web loading position, it will no longer abut and support the transfer bar  51  in its rest position as shown in FIG.  1 . As a result, the bar  66  falls out of hook  69  and the transfer bar  51  pivots about shaft  70  and rotates downwardly away from the rollers  22 ,  24  along the same or a similar path as the cover  20 . This causes both the cover  20  and the transfer bar  51  to assume their web loading positions where they will not interfere with the attendant installing the paper towel rolls in the dispenser. As discussed above, it is possible for the transfer bar  51  to experience both translational and rotational motion before reaching web loading position shown in FIG.  2 . 
     After loading the primary roll, the attendant can either feed the leading edge of the primary roll into the nip  47  or position the leading edge of the web  27  in front of the nip  47 . In a preferred embodiment, the attendant positions the leading edge in a cradle  91  located in front of the nip  47 . After positioning the web  27  in front of the nip  47 , the attendant will close the cover  20  by rotating it upward toward the chassis  12 . As the cover is rotated upward, the inner surface of cover  20  contacts the cover engaging members  53  on the transfer bar  51 , supports transfer bar  51  and rotates the transfer bar  51  toward the chassis  12 . As the cover is being closed, the post  66  moves upwardly into hook  69 . When the cover  20  is closed, the transfer bar  51  will be located in its rest position and the finger  52  will be aligned and extending in the direction of the nip  47 , as shown in FIGS. 1 and 3. 
     As the cover  20  is closed, a switch (not shown) may be engaged to activate the sensor  28  which detects the presence or absence of a leading edge of the paper web  27  on the discharge side of the feed mechanism  37 . When the absence of a web  27  is detected by the sensor  28 , the transfer system  60  and feed mechanism  37  are activated. Motor  61  drives the output gear  62  in a counter clockwise direction (as shown in FIG.  4 ). The rotating output gear  62  drives the transfer gear  65  in a clockwise direction (as shown in FIG.  4 ). This results in the transfer link  63  moving toward the rear of the chassis  12 . As the transfer link moves, hook  69  engages rod  66  and imparts the movement of the link  63  to rod  66 . As rod  66  is pulled toward the rear of the chassis  12 , the transfer bar  51  pivots toward the rear of the chassis  12  about shaft  70 . Fingers  52  move in the direction of the web  27  and engage the portions of the web  27  hanging in front of the nip  47 . The fingers  52  rotate until they abut against the driven feed roller  22  and the pressure roller  24 . As this occurs, the web is introduced into the nip  47  and taken up by the feeding mechanism  37 . When the presence of the web  27  is sensed on the discharge side of the feed mechanism  37 , the motor  61  is stopped. The return mechanism then causes the transfer mechanism  50  and the transfer bar  51  to return to their rest positions. As discussed above, this can be accomplished by using one or more coil springs or a motor  61  with a reverse drive mechanism that rotates the output gear  62  and the transfer gear  65  in the reverse direction so that transfer link  63  moves towards the closed cover  20 , thereby causing hook  69  to return the post  66  and the transfer bar  51  to their rest positions. The transfer mechanism  50  and transfer bar  51  can be activated when the cover  20  is closed by a switch located on the exterior of the dispenser. The use of a switch permits the transfer mechanism to be operated without the cover being opened and closed. When a dispenser includes supports for both a primary and a reserve roll of the web  27 , the leading edge of the reserve roll is positioned in front of the nip  47  and possibly in the cradle after the leading edge of the primary web  27  has been transferred to the feeding mechanism. When the trailing edge of the primary roll is sensed, the transfer mechanism  50  is activated for introduction of the reserve roll. This introduction is accomplished in the same manner as discussed above with respect to the introduction and feeding of the primary roll. The fingers  52  position the reserve web in the nip  47  without the cover being opened so that the reserve web is introduced into and picked up by the feeding mechanism  37  and dispensed to the user. This creates a smooth, almost instantaneous transition between the primary and reserve rolls loaded within the dispenser  10 . 
     Numerous characteristics, advantages and embodiments of the invention have been described in detail in the foregoing description with reference to the accompanying drawings. However, the disclosure is illustrative only and the invention is not limited to the illustrated embodiments. Various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention.