BACKGROUND
This invention relates generally to a method and apparatus for dispensing individual sheets from a continuous web of material, and more particularly for a dispenser housing with a motorized roller transport mechanism for loading and dispensing the material.
Known electrically powered dispensers for paper towels and the like typically include a drive roller and an associated pinch roller formed on conductive metal shafts which are supported by a molded plastic chassis, with the pinch roller being spring biased into the drive roller. Other known dispensers support the shaft ends on separate metal plates that are attached to a common housing, and typically include a separate low friction bearing material between the metal plates and the metal shafts. The known electrically powered dispensers may also be provided with a separate special purpose grounding connection between the pinch roller shaft and an external ground terminal and with motorized roller transport mechanisms utilizing a proximity detector for dispensing single sheets from a continuous web. See for example commonly assigned Moody et al U.S. Pat. No. 6,871,815 entitled Static Build Up Control in Electronic Dispensing Systems and Denen et al U.S. Pat. No. 6,838,887 entitled Proximity detection circuit and method of detecting small capacitance changes, which are both incorporated by reference in their entirety.
SUMMARY
The present invention represents an improvement over known electrically powered dispensers for paper towels or the like.
According to one aspect of the invention, a special roller bracket provides not only proper positioning of the drive and pinch roller shafts, but also tension and grounding between the drive and pinch rollers, thereby producing a dispenser that is potentially both reliable to operate and simple to assemble. the roller bracket includes a first side plate for supporting a first respective end of each of the two shafts, a second side plate for supporting a second respective end of each of the two shafts. and a mounting bar attached between the two side plates, and is integrally formed from a single sheet of conductive material. Preferably the mounting bar includes an integrally formed tear bar portion for cutting the material after it has been transported past the rollers.
In one embodiment, each side plate portion of the roller bracket includes a stationary bearing portion supporting the drive roller shaft and a moveable bearing portion supporting the pinch roller shaft, with a flexible bridge (or arm) portion connecting the stationary bearing portion to the moveable bearing portion and having a major surface parallel to the two longitudinal axes such that the pinch roller shaft is free to move laterally with respect to the drive roller shaft. Since the stationary and moveable bearing portions are integrally formed from the same sheet of conductive material, a conductive path exists from the mounting bar to each of the bearing portions. Moreover, since the flexible bridge portion is in tension when the two shafts are supported by the two side plates with the drive roller in contact with the pinch roller, each of the two conductive shafts is biased against a respective conductive bearing portion to thereby complete a static discharge path from the rollers to the mounting bar without requiring any separate springs, contacts or wires. The mounting bracket may function as a grounding terminal, or may be connected to a separate grounding terminal. In either case, a simple and reliable static electricity discharge path is provided from each of the rollers to the grounding terminal through the respective shafts and bearing surfaces.
According to another aspect of the invention, a mounting bracket including a pair of side plates separated by a connecting tear bar is formed from a single sheet of conductive material and includes a pair of fixed bearing surfaces for supporting a drive roller shaft and a pair of flexible spring arms each terminated by a moveable bearing surface for supporting a pinch roller shaft, the spring arms being formed and positioned to provide a tension force for urging the pinch roller into contact with the drive roller. The tear bar is attached to a housing and the drive roller assembly is installed into a separate chassis with the drive roller shaft inserted into a pair of chassis end plates and with a gear train coupling the drive roller shaft to a motor mounted on the chassis. The chassis assembly is then inserted into the housing between the side plates of the mounting bracket such that the drive roller shaft is free to make ohmic contact with the fixed bearing surfaces and the chassis assembly is securely attached to the housing and to the mounting bracket. The spring arms are then temporarily displaced away from the chassis assembly and the pinch roller assembly is inserted into the end plates, with moveable bearing surfaces aligned with the respective ends of the pinch roller shaft such that the tension force is applied between the pinch roller and the drive roller.
In a preferred embodiment, a respective slot in each chassis end plate constrains the drive roller shaft of the assembled transport mechanism in one lateral direction and the adjacent fixed bearing surface cooperates with the tension force from the spring arms to constrain the drive roller shaft in a second lateral direction.
Other novel aspects of the invention, including but not limited to those set forth in the appended claims, will be apparent to those skilled in the art from the referenced Drawings and from the various described Embodiment(s). In particular, the housing of a described Preferred Embodiment of a paper towel dispenser includes not only a roller-based transport mechanism, but also a door mounted projection blade for assisting paper loading, a removable top cover that also functions as a universal mounting bracket, and flexible paper protection fingers that discourage unwanted contact between the paper and the tear bar.
DRAWINGS
FIG. 1 is a perspective view of one embodiment of an exemplary dispenser housing in use.
FIG. 2 shows how a symmetric cover over the upper rear portion of the housing of FIG. 1 may function as a universal mounting bracket for attaching the housing either to a vertical or to a horizontal surface.
FIG. 3 is a cross sectional schematic view through an exemplary roller based transport mechanism, showing how web-like material such as paper may be transported from a supply roll around a drive roller, past a tear bar, and out through a discharge opening of a housing.
FIG. 4 shows an exemplary insertion blade with several projecting teeth formed on the hinged door of FIG. 3, which assist in the paper loading process.
FIG. 5 is an isometric view of one embodiment of a unitary transport roller bracket.
FIG. 6 shows how the drive roller and pinch roller of an exemplary transport mechanism may be supported by the roller bracket of FIG. 5.
FIG. 7 shows how the roller bracket of FIG. 5 may be secured to the interior of the housing of FIG. 1.
FIG. 8 shows how the drive roller of FIG. 6 may be installed into an exemplary chassis and the chassis may then be positioned between the two side plates of the secured roller bracket of FIG. 7, with a slot in the chassis cooperating with an intersecting bearing surface of the roller bracket of FIG. 5 to constrain the drive roller shaft of FIG. 6.
FIG. 9 shows how an exemplary motor and gear train may be installed on the chassis assembly of FIG. 8 after the chassis assembly has already been already installed in the housing.
FIG. 10 illustrates an inferior alternative to the embodiment of FIG. 3 with undesirable interference between a cut end of the paper and the tear bar.
FIG. 11 shows how the embodiment of FIG. 3 contains flexible curved guide fingers lacking in the embodiment of FIG. 10.
FIG. 12 shows how the teeth on the insertion blade of FIG. 4 guide the exposed folded edge of the paper roll into the nip between the drive roller and the pinch roller,
FIG. 13 shows how the folded edge of FIG. 12 may then be transported by the rollers and guided by the guide fingers towards and through the discharge opening of FIG. 3 such that the guide fingers are deflected when the user pulls on the exposed paper, thereby permitting the paper to be penetrated by the adjacent cutting teeth of the tear bar.
PREFERRED EMBODIMENT(S)
FIG. 1 is a perspective view of one embodiment of an exemplary dispenser housing 2 in use. In particular housing is provided with a rearwardly hinged lower door 4 and a discharge front opening 6 through which a predetermined length 8 from a roll 10 of paper toweling (FIG. 3) is dispensed, waiting to be torn off by the hand 12 of a user against the cutting teeth of a concealed tear bar 14 (see also FIG. 5).
FIG. 2 shows how a removable cover 16 over a battery compartment 18 provided in the upper rear portion of the housing 2 of FIG. 1 may function as a universal mounting bracket for attaching the housing 2 either to a vertical or to a horizontal surface by means of four mounting screws 20. It will be noted that except for the four holes 22, the upper 24 and rear 26 surfaces of cover 16 are mirror images of each other and are symmetrically disposed about a 45 degree axis 28, with upper surface 24 being disposed at an angle which is 90° from rear surface 26, whereby cover 16 may be installed on housing 2 with screw holes 22 exposed upwardly (to facilitate horizontal mounting under a cabinet or rearwardly (to facilitate mounting on a vertical wall. Also visible in FIG. 2 is a latch 30 which is biased forwardly and upwardly towards a corresponding one of a pair of stop ribs 32 projecting from the underside of cover 16, as well as a slot 34 on each corner of cover 16, such that the two slots 34 which are at the upper front corners of the attached cover 16 are mated with two corresponding rearwardly facing tabs 36 in at the top of housing 2. To mount the dispenser, cover 16 is first screwed or otherwise attached to a support surface, and then the housing 2 is slid rearwardly into engagement with cover 16 with the two rearwardly facing tabs 36 inserted in the two forwardly facing slots 34, until forwardly facing latch 30 has slid past and engaged the rear surface of the upper stop rib 32.
Reference should now be made to FIG. 3, which is a cross sectional schematic view through an exemplary roller based transport mechanism 38, showing how a elongated web 40 of absorbent paper toweling or other flexible material may be transported from supply roll 10, around a drive roller 42, past tear bar 14, and out through discharge opening 6 of housing 2. In the illustrated embodiment, drive roller 42 is sectioned which not only saves on material and reduces any need for a perfectly round roller, but also reduces static generation.
In particular, it should be noted that the paper material 40 is advanced from supply roll 10 to discharge opening 6 by virtue of being kept in intimate contact with the outer periphery 44 of drive roller 42 by means of a pinch roller 46, at a speed corresponding to the surface velocity of drive roller 42. Exemplary performance specifications for paper towel stock weighing 18 to 60 pounds per ream and supplied in a roll form with a nominal diameter of 3 to 6 inches would be 25 to 30 feet per minute. Also visible in FIG. 3 is the battery compartment 18 and a hinge 48 which permits door 4 to drop down for loading a replacement roll 10 of paper toweling.
FIG. 4 shows an exemplary insertion blade 50 (shown in cross section in FIG. 3) with several projecting teeth 52 formed on the hinged door 4 which cooperate with the drive roller 42 and the pinch roller 46 to assist in the paper loading process, as will be described in more detail hereinafter with respect to FIG. 12.
FIG. 5 is an isometric view of an exemplary unitary mounting bracket 54 suitable for use with one preferred embodiment of the present invention. As will become more apparent from the subsequent discussion of FIG. 6 mounting bracket 54 includes a first side plate 56A for supporting a first respective end of each of two shafts 58,60 (see FIG. 6). a second side plate 56B for supporting a second respective end of each of the two shafts 58,60, and a mounting bar 62 attached between the two side plates 56A,56B, and is integrally formed from a single sheet of conductive material such as 304 Stainless Spring Steel of 24 gauge (0.0239″). No heat treatment would be required and it could be made from rolled steel. Preferably the mounting bar 62 includes integrally formed (die stamped and then appropriately bent) tear bar portion 14 which as mentioned previously, is used for cutting a predetermined length of material after it has been transported past the rollers 42,46
Each side plate portion 56A,56B of the mounting bracket 54 includes a stationary bearing portion 64 for supporting the drive roller shaft about a longitudinal drive roller axis 66 (see also FIG. 6) and a moveable bearing portion 68 for supporting the pinch roller shaft about a longitudinal pinch roller axis 70. As shown stationary bearing portion 64 is in the shape of a half loop, to facilitate assembly, with the loop preferably being closed by a slotted plastic end wall of a separate chassis (see FIG. 8) which provides an additional bearing surface that opposes any pulling on the material as it exits the dispenser. A flexible bridge (or arm) portion 72 connects the stationary bearing portion 64 to the moveable bearing portion 68. A major surface 74 of each arm 72 is parallel to the two longitudinal axes 66,70 such that pinch roller shaft 60 is free to move laterally (arrow 76) with respect to the drive roller shaft 58, spring arms 72 being formed and positioned to provide the required tension force (on the order of 3 pounds) for urging the pinch roller 46 toward the drive roller 42 so as to prevent any undesired slippage between material 40 and drive surface 44.
Since the stationary and moveable bearing portions 64,68 are integrally formed from the same sheet of conductive material, a conductive path exists from the mounting bar 62 to each of the bearing portions 64,68. Moreover, as best seen in FIG. 6, since the flexible bridge portion 72 is in tension when the two shafts 58,60 are supported by the two side plates 56A,56B with the drive roller 42 in contact with the pinch roller 46, drive roller shaft 58 is thrust against a stationary bearing portion 64, and pinch roller shaft 60 is thrust against a moveable bearing portion 68, to thereby complete a static discharge path from rollers 42,46 to the mounting bar 62 without requiring any separate springs, contacts, rolling shafts or wires. The mounting bracket 54 may function as a grounding terminal, or may be connected to a separate grounding terminal (not shown). In either case, a simple and reliable static electricity discharge path is provided from each of the rollers 42,46 to the grounding terminal through the respective shafts 58,60 and bearing surfaces 64,68.
A preferred method of assembly will now be described with specific reference to FIG. 7, FIG. 8, and FIG. 9.
First, as shown in FIG. 7, tear bar 14 is heat staked to housing 2 using a series of pegs molded into housing 2 that protrude though respective holes 78 (FIG. 5) in mounting bar 62. Concurrently, as shown FIG. 8, drive roller assembly 42 is installed into a separate chassis 80 with the two ends of drive roller shaft 58 inserted into respective slots 82 provided in chassis end plates 84A,84B.
Next, as best seen in FIG. 8, the assembled chassis including the drive roller assembly 42 is slid between the two side plates 56A,56B of previously installed mounting bracket 54, and pushed upwardly into the housing 2 until it is properly positioned against appropriately located tabs and slots. Preferably, slots 82 in chassis end plates 84A,84B constrains the drive roller shaft 58 of the assembled transport mechanism in one lateral direction 86 (FIG. 8) and the adjacent fixed bearing surface 88 of the adjacent stationary bearing portion 64 of side plate 56 cooperates with the tension force 90 (FIG. 5) from the adjacent spring arm 72 (FIG. 5) to constrain the drive roller shaft 58 in a second lateral direction 76 (FIG. 5).
As shown in FIG. 9, spring arms 72 are temporarily displaced sideways to permit pinch roller assembly 46 to be inserted between the two arms 72, which are then released with the two ends of pinch roller shaft 60 inserted into corresponding bearing portions 68 such that tension from the spring arms 72 forces the pinch roller 46 into engagement with drive roller 42, in a direction constrained by a slot 98 in end plates 84.
To complete the assembly of chassis 80, a worm gear 86A is attached to one end of drive roller shaft 74 to thereby couple shaft 74 to a previously mounted motor and pinion assembly 88,86B, and the chassis 80 may be more rigidly secured in its operative position relative to bracket 54 by means of self tapping screws (not shown) through appropriately positioned clearance holes 90 in the side plates 56A,56B into corresponding pilot holes (not shown) in the chassis 80.
Loading of paper will now be described with reference to FIG. 4, FIG. 12 and FIG. 11. A roll 10 of paper is first loaded above door 4 (in different embodiments, it may be supported by the upper surface of door 4 or by conventional hubs and/or shafts (not shown) attached to door 4 or to the stationary interior of housing 2), and with its exposed end 100 draped over teeth 52 or insertion blade 50 framed in the still open door 4. When the door is closed (FIG. 12) insertion blade teeth 52 forces the now folded leading edge 102 into nip 104 between drive roller 47 and pinch roller 46. The motor 86 is now activated for a predetermined period of time (for example, about 3 seconds), either by means of a manual switch, or preferably by means of a timing circuit in response to automatic detection of the closing of the door 4 and the accompanying insertion of the folded paper edge 102 into nip 104 Alternatively, the motor activation can be limited to a predetermined number of rotations and/or until the folded edge 102 has been detected at a predetermined location in the vicinity of discharge opening 4.
As the paper 40 is transported from nip 104 to discharge opening 4, it is guided by a plurality of springy semicircular guide fingers 106 which are normally oriented towards drive roller 42 such that the exiting end of paper 100 is protected from any contact with teeth 108 of tear bar 14. However, as best seen in FIG. 11, when the user pulls on the exposed paper, the resultant tension causes the guide fingers 106 to be displaced away from drive roller 42 and the paper 40 is forced into penetrating contact with the teeth 108 of tear bar 14. Thus each springy finger 106 normally keeps the paper 40 off the tear bar 14, but is still sufficiently flexible to allow the tensioned paper 40 to be cut by tear bar 14.
Patent Application
20080105780
