GB2034670A - Positive-traction Sheet Finder - Google Patents

Abstract

Apparatus for feeding individual sheets of paper from a stack(s) such as contained in the copy sheet magazine of an electrostatic copier in which a pair of transversely spaced rotary saw blades are biased against the uppermost sheet of the stack and are intermittently driven to separate the uppermost sheet from the stack and initiate its movement toward a location at which an operation is to be performed on the sheet. Preferably, the teeth (102) of the saw blade are so constructed as to penetrate only a single sheet of the stack. Shoulder portions adjacent to the teeth limit the maximum penetration by the teeth. <IMAGE>

Description

SPECIFICATION Positive-traction Sheet Feeder Background of the Invention This invention relates to apparatus for individually feeding sheets of paper and, more particularly, to apparatus for individually feeding sheets of copy paper to an electrostatic copier.

There are many instances in the prior art in which the sheets of a stack must successively be fed to a predetermined location at which an operation is to be performed on a sheet. For example, sheets of copy material must be fed successively from a stack of sheets to a copy machine transfer station whereat a developed image is transferred from the surface of a photoconductor onto the surface of the copy sheet. Sheet feeding systems of the prior art for feeding copy sheets to a copy machine transfer station, for example, usually incorporate a friction feed roller and means for urging the stack and roller to move toward each other to bring the uppermost sheet in the stack into engagement with the roller with a predetermined pressure.

When a sheet is to be fed, the roller is driven to feed the uppermost sheet off the stack.

While the sheet feeding systems of the type described above have successfully fed sheets, they incorporate a number of defects. The operation of the friction roller used reiies on the existence of a greater coefficient of friction between the top sheet and the rollers than between the top and second sheets. Where the two top sheets are for one reason or another stuck together, however, the differential coefficient of friction may not be sufficient to ensure reliable separation of the sheets. Further, as friction rollers are used and their surfaces become dirty, their frictional characteristics change, resulting in a less reliable feed. Even when the friction rollers are new, their operation is highly sensitive to the particular force used to bias the rollers against the sheet being fed.

In my copending application Serial No.

898,139, filed April 20, 1978,1 describe a large capacity combination magazine and sheet feeder designed to be substituted for the existing smaller capacity copy sheet cassette of an electrostatic copier. Because of its large capacity of 1000 sheets, for example, the stack itself is disposed entirely outboard of the feeder associated with the smaller cassette. A feed roller incoporated in the magazine advances the top sheet of the stack the necessary distance to become engaged in the copy sheet transport system of the copier. To maximise its compatibility with existing machines, the magazine employs a mechanical servo system powered from an accessible feed roller shaft of the copier for positioning the top of the paper stack at the proper feed level.

The problem of reliable feed is especially acute with magazines of the type described which are disposed entirely outboard of the copier body, owing to the special geometrical constraints involved. That is while the magazine must advance the top sheet a certain minimum distance to ensure that the sheet is accepted by the sheet transport system of the copier, the magazine feed rollers must not be actuated so long that they begin to advance the second sheet.

In the magazine described in my copending application, the minimum required sheet advance is quite close to the maximum allowable advance for short sheets, so that any slippage between the magazine feed rollers and the paper becomes critical.

Summary of the Invention One of the objects of my invention is to provide a sheet feeder which reliably feeds sheets of paper one by one from a stack of sheets.

Another object of my invention is to provide a sheet feeder the performance of which does not deteriorate after a substantial period of operation.

Still another object of my invention is to provide a sheet feeder which is safe to use.

A further object of my invention is to provide a sheet feeder which minimizes the possibility of double feeds.

Still another object of my invention is to provide a sheet feeder which is not excessively sensitive to the particular biasing force used.

A further object of my invention is to provide a sheet feeder especially suitable for sheet magazines disposed entirely outboard of an electrostatic copier.

Other and further objects of my invention will become apparent from the following description.

In general, my invention contemplates apparatus for feeding individual sheets of paper from a stack in which a rotary saw blade is biased against a sheet at one end of the stack and is driven to separate that sheet from the stack.

Preferably the blade is paired with another blade transversely spaced therefrom. Shoulders adjacent to the blade teeth limit the maximum penetration by the teeth. The blade construction and biasing force are such that the teeth of the blade penetrate only a single sheet of the stack.

By relying on the positive gripping action of the saw blades rather than on friction I virtually ensure that sheets are reliably fed from the stack without any undesirable slipping. Furthermore, since the teeth of the saw blade readily penetrate the top sheet even with very little biasing force, the magnitude of biasing force is not critical.

Finally, the extreme hardness of the teeth of the saw blade relative to the paper sheets being fed ensures that the operation of the feeder will not deteriorate even after a long period of time in use.

Brief Description of the Drawings In the accompanying drawings to which reference is made in the instant specification and in which like reference characters are used to indicate like parts in the various views: Figure 1 is a fragmentary front elevation of a copy sheet magazine incorporating my sheet feeder showing the manner of its attachment to an existing electrostatic copier.

Figure 2 is an enlarged fragmentary top plan of the sheet feeder shown in Figure 1.

Figure 3 is a fragmentary section of the sheet feeder shown in Figure 2, taken along line 3-3 of Figure 2.

Detailed Description of the Preferred Embodiment Referring now to the drawings, my positivetraction sheet feeder may be used in a large capacity copy sheet magazine indicated generally by the reference numeral 10. As is fully described in my copending application Serial No. 898,139, the magazine 10 is designed to be substituted for the existing smaller capacity copy sheet cassette of an electrostatic copier indicated generally by the reference numeral 12.

Magazine 10 includes a rear wall 14 and a front wall 16. A unitary support 1 8 located between walls 1 4 and 1 6 is biased upwardly by springs 20. Support 18 receives a stack S of copy sheets to be fed. A servomechanism of any suitable type (not shown) controls the ascent of the support 18 in such a manner as to maintain the top of the stack of sheets S at the level shown in Figure 3, with the uppermost sheet just above the upper edge of a retaining wall 22 extending between rear wall 14 and front wall 1 6 at the left end of the magazine 10.While the particular servomechanism used forms no part of the present invention, an especially suitable mechanism is the mechanical servo system shown and described in the previously identified application Serial No. 898,139. Such a mechanism is located behind a cover plate 24 outside the left end of front wall 16.

My magazine includes a lower paper exit guide 26, the edges of which are formed with respective brackets 28 and 30 spaced upwardly from the upper surface of the lower guide 26. The assembly includes an upper guide 32 and respective pivot arms 34 and 36, each of which is formed with a laterally extending tongue 38. Any suitable means such as screws 40 or the like secure the edges of the upper guide and the tongues 38 of the pivot arms 34 and 36 to the brackets 28 and 30 to form an assembly which guides a sheet of paper being fed out of the magazine inwardly and generally upwardly with respect to the copier 12 in a manner to be described. Respective pivot pins 42 and 44 in walls 1 6 and 14 receive the upper ends of the pivot arms 34 and 36 swingably to support the paper exit guide assembly on the walls.

I form the central portion of the upper paper guide 32 with a generally horizontally extending bent portion 46. 1 employ any appropriate means such as screws or the like to secure a paper feed bracket 48 having spaced uprights 50 and 52 to the portion 46 of the upper guide 32. Uprights 50 and 52 rotatably support the paper feed shaft 54.

I form the base of a power takeoff bracket 56 with a pair of slots 58 which receive screws 60 for adjustably mounting the bracket 56 on the upper guide 32. Bracket 56 rotatably supports a shaft 62 carrying a sleeve 64. Shaft 62 carries for rotation therewith a power takeoff gear 66 adapted to mesh with a split gear comprising gear halves 134 and 136, which split gear is secured to an existing shaft 138 of the copier 12 which carries a paper feed roller (not shown) for rotation therewith. Shaft 62 also carries for rotation therewith a drive pulley.68 which drives a belt 70 which engages an idler belt tensioning pulley 72 on a pin 74 carried by upright 52. Upright 52 also carries a pin 75 supporting a belt roller 76. A gear 78 which rotates with pulley 76 engages a gear 80 secured to the paper feed sheet 54 for rotation therewith.Shaft 54 also carries a paper feed drive pulley 82 and a spacer 84 which cooperates with a paper feed guide arm 94 supported on the shaft to locate the gear 80 and the drive pulley 82 along the shaft. A paper feed pivot arm 86 carries a bearing housing 88 which receives a bearing (not shown) for rotatably supporting a drive roll shaft 90. A second guide arm 92 is pivoted about shaft 54 in spaced relation to arm 94 to cooperate with arm 86 to support shaft 90.

The ends of shaft 90 which extend beyond guide arms 92 and 94 in the direction of side walls 1 6 and 14 carry respective saw blade feed rollers indicated generally by reference characters 96 and 98. Each of the rollers 96 and 98 is coupled to shaft 90 through a one-way clutch 99 which couples the roll to shaft 90 upon clockwise rotation thereof as seen in Figure 3. Each feed roller 96 and 98 comprises a rotary saw blade 100 sandwiched between an outer cylindrical portion 104 and an inner cylindrical portion 1 06.

For safety reasons, the teeth 102 of the saw blade 100, which are preferably raked in the direction of feed as shown in Figure 3, extend only about 0.2 millimeter outside the periphery of portions 104 and 106. Portions 104 and 106 also limit the maximum penetration of the teeth 102 into the top sheet of the stack, which is typically about 0.09 to 0.10 millimeter thick. Since the region adjacent to the point of actual penetration is also depressed slightly by the teeth 102, cylindrical shoulder portions 104 and 106 virtually ensure that the teeth 102 penetrate only a single sheet.

Any suitable means such as snap rings (not shown) or the like may be employed to hold blades 100 parts 102 and 106 in position on shaft 90.

A belt 110 driven by pulley 82 drives a pulley 108 carried by shaft 90. Arm 86 also carries a belt idler roller 112. A traverse rod 114, which may act as a handle, passes through arm 86 and moves up and down with it. A stop in 11 6 in wall 14 limits downward movement of the traverse rod 114. The other end of the rod 114 as viewed in Figure 2 is adapted to strike the inner end of pin 118 upon a predetermined movement downward of the rod 114 to actuate the servomechanism.

The support 18 will then move upwardly, lifting the rollers 96 and 98. This lifts the traverse rod 114 out of engagement with the inner end of pin 11 8, deactuating the servomechanism. The details of this construction and the manner in which it operates are described in more detail in my copending application referred to hereinabove.

I provide my magazine with a locating bracket 120 having a pair of side arms 122 and a pair of spaced tongues 1 24 at the left edge thereof as viewed in Figures 2 and 3. My assembly also includes a pair of magazine bracing brackets 126 and 128. The cassette locating bracket side arms 122 and the bracing brackets 126 and 128 are secured to the walls 16 and 14 by any suitable means, such as screws, rivets, or the like.

To attach the sheet magazine 10 to the copier 12, the arms 122 of the bracket 120 are inserted in the cassette opening of the machine shown in Figure 1 so that braces 1 26 extend to positions at which their ends underlie a reinforcing channel 132. At the same time, each of the tongues 124 rides over a spring-loaded roller 1 30 so as properly to locate my magazine on the copy machine 1 2. Next, one or more spring-loaded rollers 131 normally at an inactive position 131' out of engagement with the underside of the lower guide 26 are moved manually or otherwise to an active position 131 pressing upwardly against the lower guide.

Arms 34 and 36, supported on pins 42 and 44 on the frame, swingably support guides 26 and 32 for movement relative to the frame. Guide 32 supports bracket 48, which carries shaft 54, which pivotally supports bracket 86, which supports the bearing housing 88 of shaft 90. This shaft supports rod 114. A cover 140 is provided with three dependent lugs 142, 144, and 146.

Lug 142 is centrally located, while lug 144 is positioned adjacent side frame 1 6 and lug 1-46 is positioned adjacent side frame 14. The rod 114 passes through lugs 144 and 146. When cover 140 is swung to the broken-line position 140' shown in Figure 3, rod 114 and rollers 96 and 98, carried by shaft 90, swing together with the cover 140 around the axis of shaft 54.

As has been described above, in the operative position of the magazine 10, rollers 131 act on the underside of guide 26. In this position, the assembly of guides 32 and 26 is swung to a position to enable saw blades 100 to engage the uppermost sheet of the stack S in the magazine 10. Gravity biases the saw blades 100 into this engagement with a total force of approximately 300 grams. Spring 1 50 limits downward movement of rollers 96 and 98 when cover 140 is raised. My apparatus also includes a back cover 148 pivoted to move through a position 148'.

While I use a biasing force of about 300 grams in the apparatus shown and described, the operation of saw blade rollers 96 and 98 is relatively insensitive to the particular value of the biasing force. Thus, if desired, the biasing pressure may be lowered to reduce the friction between the first and second sheets and hence the force tending to retard the first sheet.

In operation, where a magazine 10 provided with my positive traction feed is to be used with an existing copier, such for example as that shown in Suzuki eft at U.S. Patent 1,977,666,1 first assemble the split gear halves 134 and 136 on the copier feed roller shaft 138. Next, the magazine 10 is assembled in position in the manner previously described to replace the lower of the two cassettes of the Suzuki et al patent, for example. In this relative position of the parts, the split gear comprising halves 134 and 136 is brought into operative engagement with the gear 66. Preferably, gear halves 134 and 136 and gear 66 are formed with triangular teeth to ensure proper meshing.

It will readily be appreciated that the magazine 10 may be used independently of the copier 12 shown in the Suzuki eft at patent. That is to say, in a copier of another design, the rollers 96 and 98 can be made an integral part of the feed mechanism, with the remainder of the magazine structure being removable from the machine with which it is used. In such an arrangement, when the magazine is assembled on the copier, the saw blade feed rollers 96 and 98 would automatically be brought into engagement with the uppermost sheet in the magazine. Furthermore, my magazine may be furnished as original equipment for a copier.

It is to be emphasized that my positive traction feeding system is not limited to use with any particular machine. I have shown its use in connection with the magazine and feeder shown in my copending application for convenience and since it has some special utility in connection with such a system in addition to its general utility.

Considering the arrangement in which my magazine is used with an existing copier, after it has been assembled thereon in the manner described hereinabove, in the loading of the magazine with sheets, the cover 140, the rollers 96 and 98, the feedback actuating rod 114, and the idler 112 are pivoted around the axis of shaft 54 to the position 140' illustrated in dot-dash lines in Figure 3. Next, the rear cover is pivoted to a position at which the interior of the magazine is accessible. When this has been done, the magazine may be loaded by placing any desired number of sheets, up to the full capacity of the magazine, on the support 18. The sheets and the support may then be pushed downwardly to any intermediate position or to the bottom limit position. In either case, a brake (not shown) associated with the servomechanism and described in my copending application Serial No.

898,139, which is set, ensures that the assembly will not move upwardly under the action of the relatively heavy driver springs 20.

After the magazine has been loaded, the rear cover 148 is moved to its closed position shown in Figure 3. The rod 114 will be in its down limit position and release the brake. The stack of paper S will move up until the feed rolls 96 and 98 are thus restored to their paper-feeding position and the teeth 102 of blades 100 bite into the uppermost sheet in the stack of sheets under the influence of gravity. When a copying operation takes place, the uppermost sheet in the stack is driven through a distance sufficient along a feed path A to move its leading edge between opposing feed rollers 152 and 1 54 of the copy sheet transport system of the copier 12. One-way ciutches 99 permit rollers 96 and 98 to be overdriven, thus preventing any possible tearing of the sheet surface.

It will be seen that I have accomplished the object of my invention. My sheet feeder reliably feeds individual sheets of paper even after a substantial period of operation and is safe to use.

My sheet feeder is relatively insensitive to the particular biasing force used. Finally, because of its positive gripping action, my feeder is especially suitable for sheet magazines disposed outboard of an electrostatic copier.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Claims (11)

Claims

1. Apparatus for feeding individual sheets of paper from a stack including in combination means for supporting a stack of individual sheets of paper to be fed, a sawtooth blade, means for mounting said blade for rotary movement, means for biasing said blade into engagement with a sheet at one end of said stack to cause a blade tooth to penetrate into said sheet, and means for driving said blade to separate said sheet from said one end of said stack and to feed said sheet away from said stack, said mounting and biasing means comprising a shaft, means mounting said blade on said shaft, a frame, an arm, means mounting said shaft on one end of said arm, and means mounting the other end of said arm for pivotal movement on said frame to permit swinging movement of said blade toward and away from said sheet at said end of said stack.

2. A copy sheet magazine for use with an electrostatic copier having a copy sheet entrance port, said magazine including means for positioning a stack of copy sheets outboard of said copier with the top sheet adjacent to said entrance port, a saw blade, means mounting said blade for rotary movement, means for biasing said blade into engagement with the sheet at the top of said stack to cause a blade tooth to penetrate said sheet, and means for driving said blade to separate said sheet from said stack and to advance said sheet through said entrance port.

3. Apparatus for feeding individual sheets of paper from a stack including in combination for supporting a stack of individual sheets of paper to be fed, a sawtooth blade having raked teeth, means mounting said blade for rotary movement, means for biasing said blade into engagement with a sheet at one end of said stack to cause a blade tooth to penetrate into said sheet, and means for driving said blade in the direction of said teeth to separate said sheet from said one end of said stack and to feed said sheet away from said stack.

4. Apparatus for feeding individual sheets of paper from a stack including in combination means for supporting a stack of individual sheets of paper to be fed, a sawtooth blade, means mounting said blade for rotary movement, means for biasing said blade into engagement with a sheet at one end of said stack to cause a blade tooth to penetrate into said sheet, means for driving said blade to separate said sheet from said one end of said stack and to feed said sheet away from said stack, and cylindrical shoulder portions disposed adjacent to each side of said blade coaxially therewith, the teeth of said blade extending about 0.2 millimeter radially outwardly of said shoulder portions.

5. Apparatus for feeding individual sheets of paper from a stack including in combination means for supporting a stack of individual sheets of paper to be fed, a sawtooth blade, means mounting said blade for rotary movement, means for biasing said blade into engagement with a sheet at one end of said stack to cause a blade tooth to penetrate into said sheet, means for driving said blade to separate said sheet from said one end of said stack and to feed said away from said stack, and cylindrical shoulder portions disposed adjacent to each side of said blade coaxially therewith, the teeth of said blade extending no more than about 0.2 millimeter radially outwardly of said shoulder portions.

6. Apparatus for feeding individual sheets of paper from a stack including in combination means for supporting a stack of individual sheets of paper to be fed, a sawtooth blade, means mounting said blade for rotary movement, means for biasing said blade into engagement with a sheet at one end of said stack to cause a blade tooth to penetrate into said sheet, means for driving said blade to separate said sheet from said one end of said stack and to feed said sheet away from said stack, and a cylindrical shoulder portion disposed adjacent to a side of said blade coaxially therewith, said shoulder portion being of such a diameter as to limit the penetration by teeth of said blade.

7. Apparatus for feeding individual sheets of paper from a stack including a combination means for supporting a stack of individual sheets of paper to be fed, a sawtooth blade, means mounting said blade for rotary movement, means for biasing said blade into engagement with a sheet at one end of said stack to cause a blade tooth to penetrate into said sheet, means for driving said blade to separate said sheet from said one end of said stack and to feed said sheet away from said stack, and means adjacent to said teeth for limiting the penetration by the teeth of said blade.

8. Apparatus for feeding individual sheets of paper from the upper end of a stack including in combination means for supporting a stack of individual sheets of paper to be fed, a sawtooth blade, means mounting said blade for rotary movement, means for biasing said blade into engagement with a sheet at one end of said stack to cause a blade tooth to penetrate into said sheet, and means for driving said blade to separate said sheet from said one end of said stack and to feed said sheet away from said stack, said stack supporting means being so constructed as to maintain the upper end of the stack at a fixed reference level as sheets are successively fed therefrom.

9. Apparatus for feeding individual sheets of paper from a stack including in combination means for supporting a stack of individual sheets of paper to be fed, a sawtooth blade, means mounting said blade for rotary movement, means for biasing said blade into engagement with a sheet at one end of said stack to cause a blade tooth to penetrate into said sheet, the construction of said blade and the force exerted by said biasing means being such that the said blade tooth penetrates only a single sheet of said stack, and means for driving said blade to separate said sheet from said one end of said stack and to feed said sheet away from said stack.

10. Apparatus for feeding individual sheets of paper from a stack including in combination means for supporting a stack of individual sheets of paper to be fed, a pair of saw-tooth blades, means mounting said blades for rotary movement at axially spaced locations, means for biasing said blades into engagement with a sheet at one end of said stack to cause blade teeth to penetrate into said sheet, and means for driving said blades to separate said sheet from said one end of said stack and to feed said sheet away from said stack.

11. Apparatus for feeding individual sheets of paper from a stack including in combination means for supporting a stack of individual sheets of paper to be fed, a sawtooth blade, means mounting said blade for rotary movement, means for biasing said blade into engagement with a sheet at one end of said stack to cause a blade tooth to penetrate into said sheet, and means for driving said blade to separate said sheet from said one end of said stack and to feed said sheet away from said stack.