US3586317A

US3586317A - Sheet feed mechanism for paper

Info

Publication number: US3586317A
Application number: US749436A
Authority: US
Inventors: Louis A Smitzer
Original assignee: Stromberg Datagraphics Inc
Current assignee: ANACOMP Inc 11550 NORTH MERIDAN STREET CARMEL INDIANA 46032 A CORP OF INDIANA; Stromberg Datagraphics Inc
Priority date: 1968-08-01
Filing date: 1968-08-01
Publication date: 1971-06-22
Anticipated expiration: 1988-06-22

Abstract

Apparatus is described for individually feeding flexible sheets from a stack thereof. Roller means drive the top sheet of the stack off the remainder of the stack while a pair of hinged and weighted pressure members, in frictional engagement with the top sheet, produce displacement of the trailing corners of the sheet toward each other and thereby cause the top sheet to buckle and separate from the sheet below.

Description

United States Patent [72] Inventor Louis A. Smitzer 3.408.064 10/1968 Johnson et al. 271/61 San Diego, Calif. 2,266,068 12/1941 Peterson et a1 271/61 {21] Appl. No. 749.436 3,369,804 2/1968 Schulze et a1 271/21 [22] Filed Aug. 1,1968 3,285,601 11/1966 Zeuthen 271/17 [45] Patented June 22,1971 3,260,521 7/1966 Moxness... 271/39 [73] Assignee Stromberg Datagraphics lnc. 1.l96,36l 8/1916 Howell 271/22 San Diego, Calif. 2,827,288 3/1958 Geisler 271/24 FOREIGN PATENTS 1,127,374 41962 G 27119 54 SHEET FEED MECHANISM FOR PAPER I many 2 Claims, 4 Drawing Figs. Primary Examiner-Evon C. Blunk Assistant ExaminerH. B. Lane [52] US. Cl 22771103691, Anomey Anderson Luedeka Fitch Even and Tabin [51] lnt.Cl B65h U013 Field of Search 27H, ABSTRACT: Apparatus is described for individually feeding 36, 61, 62 flexible sheets from a stack thereof. Roller means drive the top [56] R f (Tied sheet of the stack 05 the remainder of the stack while a pair of e emnces I hinged and weighted pressure members, in frictional engage- UMTED STATES PATENTS ment with the top sheet, produce displacement of the trailing 2,285,224 6/1942 Nigra et al. 271/61 UX corners of the sheet toward each other and thereby cause the 3,104,873 9/1963 Benson et a1. 271/61 top sheet to buckle and separate from the sheet below.

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LOUIS SMITZER SHEET FEED MECHANISM FOR PAPER This invention relates to feeding apparatus and, more particularly, to apparatus for individually feeding flexible sheets from a stack thereof, such as may be incorporated in printing machines and copying machines.

in some types of machines, it is desirable to provide apparatus for individually feeding flexible sheets from a stack thereof. Thus, in many types of printing machines and copying machines, a supply of paper is provided in the form of a stack of sheets of uniform length and width. Since only one sheet is used at a time, apparatus is provided for automatically separating one sheet from the stack and feeding it into the remainder of the machine for processing. For reliable operation, such feeding apparatus should be capable of individually feeding sheets from a stack which may vary in height from only two sheets to a convenient maximum capacity, which may be a hundred or more. Generally, the sheets should be fed in singly and with a proper and consistently uniform orienta tion. It is frequently desireable that the apparatus be capable of feeding sheets of a variety of thicknesses or surface qualities.

Heretofore, apparatus capable of operating as described above has frequently been of complex construction. Not only does high complexity tend to diminish reliability, but it also tends to maintain the cost of the apparatus at a relatively high level. This may be a substantial factor in maintaining the total cost of the machine, of which the feeder apparatus is a part, undesirably high.

It is an object of this invention to provide improved apparatus for individually feeding flexible sheets from a stack thereof.

Another object of the invention is to provide feeding apparatus which is of simple construction and is reliable in operation.

A further object of the invention is to provide feeding apparatus capable of operation with a variety of stack heights and with sheets of varying thicknesses and surface qualities.

Other objects of the invention will become apparent to those skilled in the art from the following description, taken in connection with the accompanying drawings wherein:

FIG. 1 is a full section side view of a preferred form of apparatus constructed in accordance with the invention, showing an alternate position of a portion of the apparatus in phantom;

FIG. 2 is a front view of the apparatus, with part broken away, and also showing an alternate position of a portion of the apparatus;

FIG. 3 is a top view ofa part of the apparatus and;

FIG. 4 is a view of the back edge of the stack of paper which the apparatus feeds taken along the line 4-4 of FIG. 3.

Very generally, the apparatus of the invention comprises means for supporting the stack 11 of sheets and roller means 12 disposed to be in frictional engagement with the top sheet 13 of the stack. A pair of pressure members, l4, 15, are disposed to be in frictional engagement with the top sheet of the stack at regions toward the trailing edge of the top sheet at the side edges thereof. The region of engagement between the roller means and the top sheet is located toward the lead edge of the top sheet inwardly from the side edges thereof a distance sufficient to cause the pressure members to produce inward displacement of the sides of the sheet toward each other near the trailing edge when the roller means are turned to feed the top sheet. This causes the top sheet to buckle further and separate from the sheet beneath it.

Referring now more particularly to the drawings, the apparatus illustrated therein is useful in connection with an automatic copying machine. In its illustrated form, the apparatus of the invention provides a supply of copy paper in the form of a stack 11 of sheets of uniform length and width, feeding only one sheet at a time by separating one sheet from the stack and feeding it into the copying portion of the machine (not shown). The mechanism operates reliably with a stack of any height from two sheets to the maximum capacity depending upon the sheet thickness. Sheets are not double fed or fed in improper orientation, and the apparatus is capable of operating with papers of different thicknesses and surface quality.

The stack ill of paper is supported on support means consisting of a tray 10, disposed at about a 30 angle to the horizontal. The tray 10 includes a floor 16, a back 17, and two sides l9 and 21. The side 19 is provided with two out out

sections

23 and 25. Similarly, the side 21 is provided with two out out

sections

27 and 29. The tray may be made wide enough and long enough to receive 8 1% by 13 inch sheets. An adapter, not shown, may be placed in the tray to reduce its interior dimensions if a different sheet size is to be used.

The top sheet 13 of the paper stack 11 is disposed in engagement, near its forward or leading edge 33, with the roller means l2. The roller means comprise a pair of

cylinders

37 and 39 mounted on axle 41 and spaced from each other and from the outer edges of the tray such that the outer most edges of the rollers are at a position about one-third of the distance in from the sides of the tray. The cylinders are each about 1 52 inches in diameter. The axle 41 is rotatably driven by a motor, not shown, and is intermittently coupled to the motor by a clutch, also not shown. The outer surfaces of the

cylinders

37 and 39 are coated with a resilient material, such as resilient polyurethane, which is capable of gripping the top sheet of the paper with a frictional force for a wide variety of surface qualities.

As will be explained, the axle 41 is rotated to cause the

cylinders

37 and 39 to turn in the direction of the arrows indicated and feed the top sheet 13 toward a pair of

takeup rollers

43 and 45. The takeup rollers, which may be constantly rotating in the direction of the arrows indicated, grip the leading edge of the top sheet as it is fed therebetween and pass it on to the remainder of the copy machine for processing in a suitable manner.

The tray 10 is supported by a base 47 having a horizontal plate joining a pair of side plates 49 and 51. The tray is secured to the base at the sideplates plates 49 and 51 thereof by means of a pair of pivot assemblies 53. The side plates 49 and 51 of the base d7 are supported by suitable drawer slide assemblies, not shown, to be horizontally movable in the frame or cabinet of the copy machine. This facilitates loading, as will be described in detail below.

A retainer plate 57 is also supported by the base 47, being pivotally secured to the side plates 49 and 51 thereof by the pivot assemblies 53. The end of the retainer plate 57 opposite the pivot assemblies 53 is supported between a pair of latch plates 59 by a pair of latch pins 63. The latch plates are bolted to the sideplates 49 and 51 of the base 47 and extend upwardly therefrom. Each latch plate has an aperture formed therein for receiving the ends of the latch pins. The latch pins are carried in a latch tube 62 and are biased against the latch plates by a suitable spring or springs, not shown. Knobs 64, extending through a slot in the tube 62, enable the latch pins to be manually pulled toward each other and away from the latch plates. When released from the latch plates 59, the latch pins support the retainer plate by retaining on a pair of brackets 61 which are secured to the side plates 49 and 51 so that the retainer plate is disposed at about a l0 angle with respect to the horizontal. At the upper or latched position, the retainer plate 57 is disposed at about a 20 angle to the horizontal.

in order to urge the top sheet 13 of the paper stack lil against the

cylinders

37 and 39 of the feed roller means 12, the biasing means 65 are provided. The biasing means include a plate 67 which depends downwardly from the retainer plate 57 near the unpivoted end thereof. The plate 67 is provided with a plurality of holes 69 along the opposite vertical edges thereof. A pair of levers 71 are pivotally secured in openings near the unpivoted end of the retainer plate 57 by pivots 75.

The levers are L-shaped, being pivoted at the juncture of their two generally perpendicular sections or portions. The upper portions of the levers engage the underside of the floor 16 of the tray near their ends. The lower sections of the levers are provided with a plurality of holes 77 therein.

In order to urge the upper ends of the levers 71 against the underside of the floor 16, a pair of coil-type tension springs 79 are provided. Each of the springs extends from one of the holes 77 in the levers 71 to one of the holes 69 at the nearest edge of the plate 67. The size of the springs is selected to provide the desired biasing force of the top sheet 13 of the paper stack 11 against the

cylinders

37 and 39. This force may be adjusted by selecting the

proper holes

77 and 69 for securing the ends of the springs 79. The force which the springs supply is selected to exceed the weight of the paper by the required amount. The scale or spring constant of each spring is selected so that, as paper is consumed and both the weight and the height of the stack is reduced, the springs maintain, at an approximately constant pressure, the top sheet against the

cylinders

37 and 39.

Two

separator arms

83 and 85 are secured by

pivots

87 and 89, respectively, to the

sides

19 and 21 of the tray 10. A pair of supporting

brackets

91 and 93 are mounted to the ends of the

arms

83 and 85, respectively, and support a pair of pressure members or

wedges

14 and 15, respectively. The wedges are of triangular cross section and are of a resilient plastic material. The supporting brackets are of a configuration such that the wedges are supported inclined at an angle of about 30 to the vertical. The upper end of each wedge is above the top sheet 13 of the stack 11 and slightly inside the edge of the top sheet. The lower end of the wedges are below the top sheet of the stack and are outside of the outer edges of the top sheet. The wedges press on the corner of the stack in a region near the lower or trailing edge of the sheets, that is, the end of the sheets farthest from the feed roller means 12. The arms are of a sufficient weight as to urge the wedges downwardly such that they contact the upper corners of the stack of paper and cause the upper sheets to buckle slightly. The top sheet will buckle more than the other sheets because of the slant of the wedges, thereby effecting separation. A pair of legs 99 are provided on the arms 83 and-85, respectively to support the arms well above the tray 10 (show in phantom in FIG. 1) and thereby remove the wedges from contact with the paper when the apparatus is being loaded.

In operation, the clutch (not shown) may be engaged to cause the motor (also not shown) to rotate the axle 41 and the

cylinders

37 and 39. Although because of buckling produced by weight on the wedges l4 and 15, the top sheet may be separated somewhat from the sheet immediately below it due to greater buckling of the top sheet, the separation may be insufficient to insure reliable operation. In accordance with the invention, reliability is enhanced by producing forces which cause further buckling of the top sheet without buckling the sheets below it. Because the

cylinders

37 and 39 engage the top sheet further inwardly from its edges than the wedges l4 and 15, lines or vectors of tension in the top sheet are produced by the cylinders. These vectors extend from the point of engagement of each wedge with the top sheet to the point of engagement of the respective cylinders. As may be seen in FIG. 3, there is an inwardly directed component to each of the vectors, 95 and 97 so the trailing corners of the paper are forced slightly toward each other as seen in FIG. 4. Since the top sheet is buckled more than the sheets below it, the top sheet is cleanly separated from the stack so that only the top sheet is fed to the

takeup rollers

43 and 45.

The angle at which the tray 10 is supported during operation also assists in the separation of sheets, as sheets below the top sheet are urged downward by gravity, and hence toward the back 17 of the tray.

When a new stack of sheets is to be loaded in the apparatus,

the latch pins 63 are moved by squeezing the knobs 64 toward each other to release the latch pins from the latch plates 59. The retainer plate 57 is then lowered until it is supported by the pins 63 on the brackets 61 (as shown in phantom in FIG. 1). The tray 10 also moves about its pivots 53 to a smaller angle with respect to the horizontal. This enables the tra to clear the

cylinders

37 and 39 and the

rollers

43 and 45. he

assembly is then withdrawn, by sliding the base 47 out of the copying machine cabinet on the drawer slide assemblies. A new stack of paper may then be placed in the tray under the wedges l4 and 15 on arms 83 and 85 (as shown in phantom in FIG; ll). The inclined position of the tray 10 assists in the proper location of the stack of paper in the tray, as the stack is urged by gravity toward the back 17. When loaded, the apparatus is returned to its original position within the frame or cabinet of the copy machine. The retainer plate 57 is then raised until the latch pins 63 are again supported by the latch plates 59. This causes the tray to be pushed upwardly by the biasing means 65 so that the top sheet is urged against the

cylinders

37 and 39. The apparatus is thereby ready for operation.

It may therefore be seen that the invention provides improved feeding apparatus which is of simple construction and which is reliable in operation. The apparatus is capable of operation with a variety of stack heights and with sheets of various thickness and surface quality. By causing an initial buckling of the top sheet due to the downward force of the wedges l4 and 15, and by producing a further operational buckling of the top sheet due to the position of the

cylinders

37 and 39 with respect to the wedges, the top sheet is cleanly separated from the remainder of the stack for consistently reliable operation.

Various modifications of the invention, in addition to those shown and described herein, will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Such modifications are intended to fall within the scope ofthe appended claims.

What I claim is:

1. Apparatus for individually feeding flexible sheets from a stack thereof, comprising, means for supporting the stack, roller means disposed to be in frictional engagement with the top sheet of the stack toward one edge of the top sheet intermediate the side edges thereof, and a pair of pressure members disposed to be in frictional engagement with the top sheet of the stack toward the edge of the top sheet opposite said one edge and at the opposite side edges thereof and to produce forces thereon exerted toward each other, said roller means engaging the top sheet at a region displaced inwardly of the side edges of the sheet at a distance sufficient to produce inward displacement of the side edges of the sheet in the region of said pressure members when said roller means are turned to feed the top sheet, thereby separating the top sheet from the sheet below, said supporting means including a tray positioned below said roller means for receiving the stack, means for resiliently biasing said tray upwardly toward said roller means, a retainer plate disposed below said tray and supporting said biasing means, and a slidable base supporting the said retainer plate and said tray, said retainer plate being pivotally mounted to said base.

2. Apparatus according to claim 1, wherein said biasing means include at least one pivotal lever having a fulcrum fixed with respect to said retainer plate and having a first portion displaced from said fulcrum and engaging the underside of said tray, said biasing means further including a spring secured to a second portion of said lever displaced from said fulcrum and said first portion.