US3883132A

US3883132A - Paper feed control mechanisms

Info

Publication number: US3883132A
Application number: US379549A
Authority: US
Inventors: John L Swanson
Original assignee: AB Dick Co
Current assignee: AB Dick Co
Priority date: 1973-07-16
Filing date: 1973-07-16
Publication date: 1975-05-13
Anticipated expiration: 1992-05-13
Also published as: FR2237828A1; DE2433505C2; NL7409527A; JPS5043926A; GB1475342A; JPS5337225B2; CA1024538A; DK379574A; DE2433505A1; FR2237828B1; BR7405885D0

Abstract

A duplicating machine of the type employing a table for holding a stack of paper sheets. The machine includes feed mechanisms which engage the top sheet of the stack and thereby feed the sheets one at a time to the duplicating mechanisms of the machine. The particular improvement of the invention involves an automatic control means for the operation of the feed member, the control means being dependent upon the location of the top of the stack. The control means include a latch lever connected to a support for feed rollers or other feed members, and the latch lever moves with the feed member support as the feed member changes position in response to a change in the height of the stack. When the height of the stack reaches a predetermined position, the latch lever engages the means for driving the feed member to automatically stop the feeding operation. The automatic operation occurs whenever the amount of paper in the stack is reduced beyond a predetermined level or when the table is deliberately lowered. The latch lever is automatically released for resumption of the feeding operation when the stack height is raised above the predetermined level.

Description

[ May 13, 1975 PAPER FEED CONTROL MECHANISMS for holding a stack of paper sheets. The machine int L cludes feed mechanisms which engage the top sheet of [75] lnvemor' John L Swanson Llber yvlne the stack and thereby feed the sheets one at a time to [73] ASSigneeI c Comp y, Niles. the duplicating mechanisms of the machine. The particular improvement of the invention involves an auto- }l22] Flled' July 1973 matic control means for the operation of the feed [21] Appl. No.: 379,549 member, the control means being dependent upon the location of the top of the stack. The control means in- [52] U 5 Cl 27l/ll0 271/116 271/117 clude a latch lever connected to a support for feed rol- [51] B65h 3/06 lers or other feed members, and the latch lever moves [58] Fieid 116 I17 with the feed member support as the feed member 10 l l changes position in response to a change in the height of the stack. When the height of the stack reaches a References Cited predetermined position, the latch lever engages the means for driving the feed member to automatically UNITED STATES PATENTS stop the feeding operation. The automatic operation 6/1940 271/] 17 c s whenever the amount of paper in the stack is United States Patent Swanson PATENTED HAY 1 3975 3,883,132

SHEET 10F 3 FIG: 1

FIG. 2

PAPER FEED CONTROL MECHANISMS This invention is directed to improvements in duplicating equipment. In particular, the invention relates to duplicators, printing presses, and related equipment incorporating feeding mechanisms which are adapted to feed individual sheets from a stack of sheets located in or adjacent the equipment.

In typical duplicating machines, a table is provided for supporting a stack of paper sheets. Feeding mem bers, usually feed rollers, are provided for engaging the top sheet in a stack for thereby feeding the sheet into position for a copying operation. The feeding mechanisms are driven in a repetitive fashion so that a continuous movement of the individual sheets is achieved.

In previous duplicating equipment, the operator would locate a stack of paper on the feed table and then turn a knob or perform some other operation which would raise the table and the associated stack of paper to the feed level. Once the feed level is reached, the operator then turned on the feeding mechanisms. This could result in a misfeed if the operator accidentally turned on the paper feed first and then operated the table raise mechanism.

After operation of the duplicating machine for a period of time, it becomes necessary to replenish the supply of paper. In previous equipment, this is accomplished by turning off the feed mechanisms at which time the feed table can be lowered, the paper replenished, the feed table raised to the feed position, and the feed mechanism then turned back on.

It is a general object of this invention to provide improvements over previous duplicating equipment with respect to the mechanisms employed for achieving operation of paper feeding mechanisms.

It is a more specific object of this invention to provide improvements in feeding mechanisms for duplicating machines whereby requirements'for turning feeding mechanisms on and off in order to supply and replenish paper are significantly reduced.

It is a still further object of this invention to provide automatic paper feed on-off mechanisms which can be efficiently incorporated in duplicating equipment whereby the operator time required for duplicating is reduced.

These and other objects of this invention will appear hereinafter and for purposes of illustration, but not of limitation, specific embodiments of the invention are shown in the accompanying drawings in which:

FIG. 1 is a side elevation of a duplicating machine;

FIG. 2 is a plan view of the duplicating machine shown in FIG. 1;

FIG. 3 is an enlarged detail view illustrating the feed and automatic latch mechanisms employed in the construction of the invention;

FIG. 4 is a further detail view illustrating portions of the feed and latch mechanisms;

FIG. 5 is a fragmentary view ofa feed roller and associated support and drive mechanisms taken about the line of 5-5 of FIG. 3; and,

FIGS. 6, 7 and 8 comprise additional detail views of portions of the feed and latch mechanisms utilized in the construction.

The apparatus of the invention generally comprises a duplicating machine having a table for holding a stack of paper sheets. At least one feed roller or other feed member is provided for engaging the top sheet of a stack and drive means are employed for operating the feed member so that the sheets are fed one at a time to a duplicating position.

A latch lever is operatively connected to a support for the feed member, and this support moves with the feed member as the height of the paper stack changes. Thus, the support will gradually drop as the sheets are removed one at a time from the table. In addition, the feed member support will drop whenever the table is lowered, for example when the stack of sheets is being replenished.

The latch lever associated with the feed member support is adapted to move into engagement with the drive means for the feed member whenever the support has moved to a predetermined position. Engagement of the latch lever with the drive means operates to disable the drive means whereby the feeding operation is automatically stopped when the predetermined level is reached, there being no requirement for an operator to independently actuate a stop mechanism. In cases where the feeding operation is stopped with the table being lowered to enable replenishing of paper supply, the latch lever will be automatically disengaged when the table is raised to the operating position. Again, there is no necessity for independent action by an operator to restart the mechanism once the paper supply has been replenished.

The accompanying drawings illustrate a duplicating machine 10 which may be any one of several existing types of machines. A table top machine is illustrated; however, the concepts of the invention are applicable to larger machines and to printing presses and duplicating equipment of many other types. I

In accordance with the design of previous equipment, the machine includes a feed table 12 which will support a stack of paper sheets. A pair of feed rollers 14 are mounted on a shaft 16 of rectangular cross section, and this shaft is journalled at one end to the support member 18. The opposite end of the shaft is received within the support housing 20, this housing including drive mechanisms to be described.

The paper sheets fed into the duplicating machine are moved by appropriate conveyor means to a duplicating position and are then discharged onto the table 22. A knob 24 is provided for controlling the movement of the table 12 with a ratchet and pinion arrangement, for example of the type shown in Zahradnik US. Pat. No. 3,273,884, being suitably employed for achieving a raising and lowering operation. A main control knob 26 is employed for starting the various op erating mechanisms including the feed drive mechanisms.

The details of the drive and latch mechanisms comprising a preferred form of the invention are illustrated in FIGS. 3 through 8. These mechanisms include a drive cam 28 which is tied to a continuously rotating shaft connected to a main drive motor for the machine. The lobe 30 of the cam is adapted to engage the roller 32 mounted at the end of drive lever arm 34. The lever arm 34 is pivoted about stub shaft 36 which may be attached to the duplicator housing.

A drive arm 38 is tied to lever 34 through sleeve 40 whereby pivoting movement of the lever 34 about shaft 36 results in swinging reciprocal movement of the drive arm 38. A drive link 42 is connected to the arm 38 by means of an adjustable pin 44 received in the slot 46 defined at the end of the drive arm. The adjustability of the position of the pin 44 relative to the slot 46 permits adjustment of the drive stroke imparted by the arm 38.

The opposite end of link 42 is attached to crank arm 48 by means of a pin 50, the pin being rotatable relative to the link. Accordingly, the reciprocal movement which is imparted to the link 42 results in a swinging reciprocal movement for the crank arm 48.

A shaft 52 supporting crank arm 48 also supports a segment gear 54, the latter being integrally formed with the crank arm. This segment gear meshes with idler gear 56 which in turn drives gear 58. The latter, as shown in FIG. 5, fits around the end 60 of the shaft 16, and pins 62 secure this gear to a one-way over-running clutch 64.

In the feeding operation of the mechanisms illustrated, the cam 28 continuously pivots the lever 34, and the resulting swinging movement of drive arm 38 causes swinging movement of segment gear 54 through the operation of link 42 and crank arm 48. The

gears

56 and 58 rotate back and forth in response to the movement of the segment gear. Since the gear 58 is not tied to the shaft 16, the movement of this gear affects only the clutch 64 and, therefore, the shaft 16 and associated feed rollers 14 rotate in only one direction. Considering FIGS. 3 and 4, this feed roller rotation is clockwise whereby a sheet in paper stack 66 is fed into the duplicating machine during each revolution of the cam The supports 18 and for the opposite ends'of the shaft 16 are connected to the machine housing for pivoting movement about opposing stub shafts 68. The shaft 52 supporting segment gear54 and the integrally formed crank arm 48 comprises an extension of the stub shaft 68 which carries the support 20. The supports 18 and 20 move about their respective connections depending upon the height of the paper stack so that the rollers 14 will continue to engage the top sheet in a stack as the height of the stack decreases during feeding.

An outwardly extending ear 70 is formed in the support 20 and a nut 72 is secured to this ear. Adjusting screw 74 is received by the nut whereby the end of the screw can be moved toward and away from the ear. A lever 76 is also mounted on stub shaft 68, and a tab 78 at one end of this lever provides a connection for tension spring 80. A pin 82 which is attached to the machine frame secures the opposite end of the spring, and spring action serves to force the tab 19 at the other end of the lever 76 into engagement with the end of the screw 74. Accordingly, the lever 76 will follow the movement of the

supports

18 and 20 with the specific relationship of the lever 76 and the supports being determined by the position of the adjusting screw 74.

An additional tension spring 84 has one end connected to pin 86 carried by the lever 76. The opposite end of this spring is attached to pin 88 carried by lever 90. The lever 90 is pivotally mounted on a stub shaft 92 which is carried by latch lever 94. A tab 96 at the end of lever 90 engages the end of adjusting screw 98 which is threadably received by the nut 100 carried on the car 102 formed in the latch lever 94. The latch lever 94 defines a hook end 106 which is maintained in spaced relationship relative to the ear 108 formed in drive arm 34 during the feeding operation.

A third spring 110 is connected at one end to pin 112 carried by lever 76 and the other end of this spring is connected to a tab 114 carried by the lever 90. The spring 110, therefore, urges the lever 90 into engagement with the spring pin 112 (see FIG. 4). At the same time, the spring 84 urges the latch lever 94 to pivot in a counterclockwise direction toward the lever 90 thereby normally urging the screw 98 into engagement with the ear 96.

The roller 32 which bears against the cam 28 is normally urged into engagement with the cam by means of spring 118. This spring has one end connected to pin 120 located on the arm 38, and the other end is connected to pin 122 which is secured to the machine frame. The spring 118 operates to urge the assembly of the drive lever 34 and the arm 38 in a counterclockwise direction so that the roller 32 will always bear against the cam 28 unless the lever arm 34 is latched against pivoting movement.

In the operation of the construction illustrated, the

supports

18 and 20 will pivot in a clockwise direction either gradually during the course of a feeding operation or abruptly if the table 12 is lowered. In either case, the adjusting screw 74 will bear against lever 76 to pivot this lever clockwise relative to the drive lever 34. This, in turn, will cause the spring 110 to pull the lever 90 for pivoting of this lever clockwise about shaft 92. This action causes the lever 90 to bear downwardly on adjusting screw 98 which causes the hook end 106 of the latch lever 94 to move toward the ear 108.

In the illustrated embodiment, the roller 32 is engaged with the lobe of cam 28 whereby the ear 108 of lever 34 is in its lowest position. As the cam movement continues, the roller 32 will follow the cam surface thereby moving the ear 108 upwardly as the lever 34 pivots about the axis 36. If, however, the hook end 106 of the latch lever 94 is moved sufficiently to engage the car 108, the ear and the associated lever 34 will be restrained against pivoting movement. The cam 28 will continue to rotate; however, the lever 34 will remain stationary thereby shutting off any drive to the rollers 14. This latching action occurs automatically in response to lowering of the height of the paper stack since the height of the stack controls the position of the

supports

18 and 20 which, in turn, control the position of the latch lever 94. Disabling of the drive movement occurs automatically when the supports are lowered,

' and it will be appreciated that disengagement of the latch lever with the ear 108 will also occur automatically when the position of the top of the paper stack is raised to the extent that pivoting movement of the support will move the latch lever out of contact with the ear 108.

With the arrangement shown, the operator need only operate the main control knob 26 at the outset of a duplicating operation. If the duplicating operation is al lowed to progress to the point that the paper is depleted or the height thereof has dropped below an operating level, then the feeding operation will automatically stop even though the cam 28 will continue to rotate. In this connection, an audio or visual signal may be utilized to advise the operator that a replenishing of the paper supply is necessary.

After replenishing the paper supply, the operator simply raises the table to the desired height, and the feeding operation will commence as soon as the top of the paper stack reaches a predetermined position. In other circumstances, it may be desirable to lower the table before the paper stack has been depleted to the extent that the feeding mechanisms are disabled. Under these circumstances, the lowering of the table by means of the knob 24 will itself result in shutting off of the feeding operation.

The

levers

76 and 90 operate as position control le vers in the arrangement described. Thus, the adjusting screw 74 varies the relative positions of the lever 76 and support while the adjusting screw 98 varies the relative positions of the lever 90 and latch lever 94. These relative positions determine the point at which the latch lever will engage the drive lever 34 as the support 20 moves downwardly in accordance with the paper height.

The described arrangement also provides for adjustment of the feed roller action. Specifically, adjustment of the pin 44 along the slot 46 changes the effective lever arm of the arm 38 thereby affecting the angular motion imparted to the segment gear 54 which controls the feed roller rotation. With this arrangement, the distance of movement of the topmost sheet into the machine is readily controlled.

The lever arm 90 defines a hooked end 124 which is connected to the table raising mechanism. The construction of the invention may utilize a standard paper stack height sensing mechanism. Specifically, the lever 90 normally is latched to a table raising power lever (not shown) which is periodically released by movement of the lever 90 as the latter pivots in response to lowering of the paper stack height. Such power lever permits a drive for the paper stack table to operate and raise the table until the lever 90 is again latched.

The construction illustrated includes a latch 116 which is adapted to engage an additional car 119 carried by the drive lever 34. The latch 116 is connected to control knob 26, and pivoting of the latch in a counterclockwise direction from the position shown in FIGS. 3 and 4 will operate to free the drive arm for feeding movement. Thus, release of the latch 116 is required at the outset of the duplicating operation with the control of the feeding being thereafter determined by the position of the

supports

18 and 20. It will be appreciated that the position of the latch 116 in FIGS. 3 and 4 will prevent any feeding operation since this latch will hold the drive lever 34 stationary so that the roller 32 cannot follow the cam 28.

It will be understood that various changes and modifications may be made in the above described construction which provide the characteristics of the invention without departing from the spirit thereof particularly as defined in the following claims.

' That which is claimed is:

1. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed member for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising secondary control means for automatically con trolling the feeding operation of the feed member depending upon the location of the top of said stack, said control means including a latch lever, means operatively connecting said latch lever to said feed member, said latch lever moving with said feed member as the feed member changes position in response to a change in the height of said stack, the movement of the latch lever resulting in engagement of the latch lever with the means for driving said feed member when the top of the stack reaches a predetermined position, the engagement of the latch lever with the means for driving the feed member stopping the driving of the feed member.

2. A mechine in accordance with claim 1 including a support for said feed member, said means operatively connecting said latch lever including said support, and said support being movable with said feed member as the feed member moves in response to changes in location of the top of said stack.

3. A machine in accordance with claim 2 wherein said feed member comprises at least one feed roller, said support comprising means for journalling the feed roller, said drive means including a clutch whereby said feed roller is adapted to rotate in only one direction for achieving successive feeding of the individual sheets.

4. A construction in accordance with claim 3 wherein said drive means include a cam and a drive lever, the cam engaging one end of said drive lever, said cam imparting pivoting movement to said drive lever during each rotation of the cam, gear means operatively connected to said drive lever whereby rotary movement is imparted to said gear means during pivoting movement of the drive lever, said gear means being connected to,

said feed roller through said clutch means.

5. A machine in accordance with claim 4 wherein said latch lever is adapted to move into engagement with said drive lever, said latch lever preventing pivoting movement of said drive lever when engaged with the drive lever.

6. A machine in accordance with claim 1 wherein said feed member gradually follows the top of said stack as the location of the top of said stack changes upon removal of successive sheets from the stack.

7. A machine in accordance with claim 1 wherein said table is adjustably mounted, said feed member moving in response to lowering of the table during replacement of paper on the table whereby said feed member stops operation when the table is lowered, and wherein said latch lever is automatically disengaged when the table is raised after replacement of paper on the table.

8. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed member for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising means for automatically controlling the feeding operation of the feed member depending upon the location of the top of said stack, said control means ineluding a latch lever, a support for said feed member, said latch lever being connected to the support and said support and latch lever being movable with said feed member as the feed member moves in response to V changes in location of the top of said stack, the movethereby vary the predetermined position at which said latch lever engages said means for driving said feed member.

9. A machine in accordance with claim 8 wherein said position control lever means include a first lever, spring means urging said first lever against said support, and an adjustable screw carried by the support for varying the relative position of said first lever and the support.

l0.-A machine in accordance with claim 9 including an additional adjusting screw carried by said latch lever, a second position control lever engaging said additional adjusting screw, and additional spring means connecting said second position control lever and said latch lever, said additional adjusting screw operating to vary the relative positions of said second position control lever and said latch lever in opposition to said additional spring means.

11. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed member for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising means for automatically controlling the feeding operation of the feed member depending upon the location of the top of said stack, said control means including a latch lever, a support for said feed member, said latch lever being connected to the support and said support and latch lever being movable with said feed member as the feed member moves in response to changes in location of the top of said stack, said feed member comprising at least one feed roller, said support comprising means for journalling the feed roller, said drive means including a clutch whereby said feed roller is adapted to rotate in only one direction for achieving successive feeding of the individual sheets, the movement of the latch lever resulting in engagement of the latch lever with the means for driving said feed member when the top of the stack reaches a predetermined position, the engagement of the latch lever with the means for driving the feed member stopping the driving of the feed member, said means for driving including a cam and a drive lever, the cam engaging one end of said drive lever, said cam imparting pivoting movement to said drive lever during each rotation of the cam, gear means operatively connected to said drive lever whereby rotary movement is imparted to said gear means during pivoting movement of the drive lever, said gear means being connected to said feed roller through said clutch means, said gear means including a reciprocally movable segment gear, a drive arm connected to said drive lever for imparting driving force to the segment gear, and means for adjusting the effective length of said drive arm to thereby vary the angular rotation of the segment gear for in turn varying the feed rotation of said feed roller.

12. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed member for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising secondary control means for automatically controlling the feeding operation of the feed member depending upon the location of the top of said stack, said control means including a latch lever, means operatively connecting said latch lever to said feed member, said latch lever moving with said feed member as the feed member changes position in response to a change in the height of said stack, the movement of the latch lever resulting in disengagement of the latch lever with the means for driving said feed member when the top of the stack reaches a predetermined position, the disengagement of the latch lever with the means for driving the feed member starting the driving of the feed member.

13. A machine in accordance with claim 12 including a support for said feed member, said means operatively connecting said latch lever including said support, and said support being movable with said feed member as the feed member moves in response to changes in location of the top of said stack.

14. A machine in accordance with claim 13 wherein said feed member comprises at least one feed roller, said support comprising means for journalling the feed roller, said drive means including a clutch whereby said feed roller is adapted to rotate in only one direction for achieving successive feeding of the individual sheets.

15. A construction in accordance with claim 14 wherein said drive means include a cam and a drive lever, the cam engaging one end of said drive lever, said cam imparting pivoting movement to said drive lever during each rotation of the cam, gear means operatively connected to said drive lever whereby rotary movement is imparted to said gear means during pivoting movement of the drive lever, said gear means being connected to said feed roller through said clutch means.

16. A machine in accordance with claim 15 wherein said latch lever is adapted to move into engagement with said drive lever, said latch lever preventing pivoting movement of said drive lever until disengaged from the drive lever.

17. A machine in accordance with claim 12 wherein said feed member gradually follows the top of said stack as the location of the top of said stack changes upon removal of successive sheets from the stack,

18. A machine in accordance with claim 12 wherein said table is adjustably mounted, said feed member moving in response to lowering of the table during replacement of paper on the table whereby said feed member stops'operation when the table is lowered, and wherein said latch lever is automatically disengaged when the table is raised after replacement of paper on the table.

19. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed member for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising means for automatically controlling the feeding operation of the feed member depending upon the location of the top of said stack, said control means including a latch lever, a support for said feed member, said latch lever being connected to the support and said support andlatch lever being movable with said feed member as the feed member moves in response to changes in location of the top of said stack, the movement of the latch lever resulting in disengagement of the latch lever with the means for driving said feed member when the top of the stack reaches a predetermined position, the disengagement of the latch lever with the means for driving the feed member starting the driving of the feed member, and wherein said means connecting said latch lever to said support comprises position control lever means movable with said support, said position control lever means including adjusting means for varying the relative positions of said support and said latch lever to thereby vary the predetermined position at which said latch lever engages said means for driving said feed member.

20. A machine in accordance with claim 19 wherein said position control lever means include a first lever, spring means urging said first lever against said support, and an adjustable screw carried by the support for varying the relative position of said first lever and the support.

21. A machine in accordance with claim 20 including an additional adjusting screw carried by said latch 1ever, a second position control lever engaging said additional adjusting screw, and additional spring means connecting said second position control lever and said latch lever, said additional adjusting screw operating to vary the relative positions of said second position control lever and said latch lever in opposition to said additional spring means.

22. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed memher for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising means for automatically controlling the feeding operation of the feed member depending upon the location of the top of said stack, said control means including a latch lever, a support for said feed member, said latch lever being connected to the support and said support and latch lever being movable with said feed member as the feed member moves in response to changes in location of the top of said stack, said feed member comprising at least one feed roller, said support comprising means for journalling the feed roller, said drive means including a clutch.whereby said feed roller is adapted to rotate in only one direction for achieving successive feeding of the individual sheets, the movement of the latch lever resulting in disengagement of the latch lever with the means for driving said feed member when the top of the stack reaches a predetermined position, the disengagement of the latch lever with the means for driving the feed member starting the driving of the feed member, said means for driving including a cam and a drive lever, the cam engaging one end of said drive lever, said cam imparting pivoting movement to said drive lever during each rotation of the cam, gear means operatively connected to said drive lever whereby rotary movement is imparted to said gear means during pivoting movement of the drive lever, said gear means being connected to said feed roller through said clutch means, said gear means including a reciprocally movable segment gear, a drive arm connected to said drive lever for imparting driving force to the segment gear, and means for adjusting the effective length of said drive arm to thereby vary the angular rotation of the segment gear for in turn varying the feed rotation of said feed roller.

Claims

1. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed member for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising secondary control means for automatically controlling the feeding operation of the feed member depending upon the location of the top of said stack, said control means including a latch lever, means operatively connecting said latch lever to said feed member, said latch lever moving with said feed member as the feed member changes position in response to a change in the height of said stack, the movement of the latch lever resulting in engagement of the latch lever with the means for driving said feed member when the top of the stack reaches a predetermined position, the engagement of the latch lever with the means for driving the feed member stopping the driving of the feed member.

4. A construction in accordance with claim 3 wherein said drive means include a cam and a drive lever, the cam engaging one end of said drive lever, said cam imparting pivoting movement to said drive lever during each rotation of the cam, gear means operatively connected to said drive lever whereby rotary movement is imparted to said gear means during pivoting movement of the drive lever, said gear means being connected to said feed roller through said clutch means.

8. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed member for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising means for automatically controlling the feeding operation of the feed member depending upon the location of the top of said stack, said control means including a latch lever, a support for said feed member, said latch lever being connected to the support and said support and latch lever being movable with said feed member as the feed member moves in response to changes in location of the top of said stack, the movement of the latch lever resulting in engagement of the latch lever with the means for driving said feed member when the top of the stack reaches a predetermined position, the engagement of the latch lever with the means for driving the feed member stopping the feeding operation, and wherein said means connecting said latch lever to said support comprises position control lever means movable with said support, said position control lever means including adjusting means for varying the relative positions of said support and said latch lever to thereby vary the predetermined position at which said latch lever engages said means for driving said feed member.

10. A machine in accordance with claim 9 including an additional adjusting screw carried by said latch lever, a second position control lever engaging said additional adjusting screw, and additional spring means connecting said second position control lever and said latch lever, said additional adjusting screw operating to vary the relative positions of said second position control lever and said latch lever in opposition to said additional spring means.

17. A machine in accordance with claim 12 wherein said feed member gradually follows the top of said stack as the location of the top of said stack changes upon removal of successive sheets from the stack.

18. A machine in accordance with claim 12 wherein said table is adjustably mounted, said feed member moving in response to lowering of the table during replacement of paper on the table whereby said feed member stops operation when the table is lowered, and wherein said latch lever is automatically disengaged when the table is raised after replacement of paper on the table.

19. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed member for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising means for automatically controlling the feeding operation of the feed member depending upon the location of the top of said stack, said control means including a latch lever, a support for said feed member, said latch lever being connected to the support and said support and latch lever being movable with said feed member as the feed member moves in response to changes in location of the top of said stack, the movement of the latch lever resulting in disengagement of the latch lever with the means for driving said feed member when the top of the stack reaches a predetermined position, the disengagement of the latch lever with the means for driving the feed member starting the driving of the feed member, and wherein said means connecting said latch lever to said support comprises position control lever means movable with said support, said position control lever means including adjusting means for varying the relative positions of said support and said latch lever to thereby vary the predetermined position at which said latch lever engages said means for driving said feed member.

21. A machine in accordance with claim 20 including an additional adjusting screw carried by said latch lever, a second position control lever engaging said additional adjusting screw, and additional spring means connecting said second position control lever and said latch lever, said additional adjusting screw operating to vary the relative positions of said second position control lever and said latch lever in opposition to said additional spring means.

22. In a duplicating machine including a table for holding a stack of paper sheets, at least one feed member for engaging individual sheets to feed the sheets to the duplicating mechanisms, means for driving the feed member for achieving the feeding operation, and primary means for controlling the operation of the means for driving the feed member, the improvement comprising means for automatically controlling the feeding operation of the feed member depending upon the location of the top of said stack, said control means including a latch lever, a support for said feed member, said latch lever being connected to the support and said support and latch lever being movable with said feed member as the feed member moves in response to changes in location of the top of said stack, said feed member comprising at least one feed roller, said support comprising means for journalling the feed roller, said drive means including a clutch whereby said feed roller is adapted to rotate in only one direction for achieving successive feeding of the individual sheets, the movement of the latch lever resulting in disengagement of the latch lever with the means for driving said feed member when the top of the stack reaches a predetermined position, the disengagement of the latch lever with the means for driving the feed member starting the driving of the feed member, said means for driving including a cam and a drive lever, the cam engaging one end of said drive lever, said cam imparting pivoting movement to said drive lever during each rotation of the cam, gear means operatively connected to said drive lever whereby rotary movement is imparted to said gear means during pivoting movement of the drive lever, said gear means being connected to said feed roller throUgh said clutch means, said gear means including a reciprocally movable segment gear, a drive arm connected to said drive lever for imparting driving force to the segment gear, and means for adjusting the effective length of said drive arm to thereby vary the angular rotation of the segment gear for in turn varying the feed rotation of said feed roller.