JPS5978016A - Sheet feeder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a friction feeding device for feeding paper sheets from a stack. More particularly, the present invention relates to a feeding device characterized by an endless flexible friction belt at one end that sits or "floats" over the sheet under its own weight.

The geometrical relationship and normal force between the belt and the top of the paper stack are important in achieving good feeding motion. Although conventional feeders such as those illustrated in the aforementioned patents have been used with some success in combination with today's high speed copiers, their effectiveness is limited by the underlying mechanism. There is. Some use sophisticated mechanisms to hold the feed belt offset in contact with the paper stack, but these mechanisms limit the belt's freedom of movement and therefore interfere with the paper stack condition. often limits the belt's ability to adapt to changes in For example, the mere fact that the belt is rotatably mounted on two pulleys limits the belt's freedom of movement to one axis. Furthermore, contact between the belt and the stack is constrained and often intentionally limited in conventional feeding devices to a small area on the stack by the orientation of the feed belt and pulleys and their placement with respect to the stack.

If the belt's movement is restricted to one axis, the belt will not be able to follow the paper stack and will be sensitive to changes in stack height. As a result, undesirable misfeeds often occur.

Such a feeding device is typically shown in Stan, GE, US Pat. No. 3,768,803 (noted above). In the standge version, the feed belt removes the top sheet of paper from the stack and also (in conjunction with the blocking member on which it rides) forms an alignment slot in which the sheets are separated and aligned. Features a composition. The Stange version minimizes bonding between sheets and limits contact between the feed belt and the stack to a single point at the stack edge so that the belt acts on the sheets over the longest distance.

This configuration relies on such minimal contact between the stack and the sheets and also because the movement of the feed belt itself is restricted to its path around the pulleys to which it is attached. The standge configuration is relatively sensitive to changes in paper type and quality as well as changes in stack height. Stange U.S. Pat. No. 3,941,373 shows a similar arrangement.

Lindquist U.S. Patent No. 3
No. 485,489 also teaches a belt feeding device in which the belt is arranged on a pair of pulleys to form a so-called tractor, which is arranged to move paper sheets from a stack to an adjacent horizontal surface. In this configuration, the triter is able to pivot from an engaged position with the stack to a disengaged position flf, but the belt's freedom of movement and its contact with the stack is restricted.

U.S. Pat. No. 3,734,490 to Park illustrates a feed mechanism in which a belt is threaded over a pair of pulleys and passes through an idler wheel disposed between the pulleys in a beltway. The pulley to which the belt is attached is spaced apart from the stack, but the idle wheel can move up and down to force the belt into engagement with the upper document in the stack. Lindquist and Parker indicate other drawbacks of conventional friction belt feeding devices. That is, the belt is often biased during sheet stacking using elaborate mechanisms that are costly and subject to mechanical failure of their own.

Bottom feeders, ie, feeders configured to remove sheets from the bottom of a stack, sometimes take greater advantage of the flexibility of the belt and its ability to follow sheet conditions. (5trobel
), U.S. Pat. No. 3,934,869, and Kyh
l), US Pat. No. 3,988,017. However, these configurations have their own drawbacks, particularly as the normal force between the stack and the belt changes as the amount of paper in the stack decreases. Thus, although friction feed belts are widely used in paper feed devices, there is still a need for improvement. In particular, there is a need for a feeding device that is well-adapted and insensitive to changes in stack height and paper condition.

The main object of this invention is to provide a friction belt feeding device in which the belt readily adapts to changes in stack height and follows the surface conditions of the paper.

Another object of the invention is to provide a friction belt feeder in which the normal force is uniformly distributed over the belt surface, where high pressure point loads are avoided and sheet-to-sheet bonding is minimized. It is.

Although these objectives are achieved by this invention, the-
An example configuration is such that one end of the belt is held by a belt holding device around a drive pulley that drives the belt in rotation, and the other end of the belt is free-floating under its own weight over the stack of sheets or documents to be fed. A sheet feeding apparatus is provided which is characterized by a cantilevered endless feeding belt with a friction surface that frictionally engages the topmost sheet. A positioning device is provided to support the floating end of the belt out of engagement with the stack when no sheets are to be fed, and to allow the belt to float over the stack during feeding operations.

In another embodiment of the invention, the sheet feeding device uses a blocking member on the upper part of which the belt also floats, which blocking member prevents the uppermost sheet of the stack from occasionally touching the uppermost sheet during the feeding operation. By blocking the progress of a certain second sheet, two or more sheets are prevented from being fed by the belt at the same time. Preferably, the friction surfaces of the belt and the blocking member are such that the belt has a higher coefficient of friction against the paper than the blocking member.

Because the feed belt of the present invention floats freely in the paper stack, it immediately responds to and is virtually insensitive to changes in paper condition or stack height.

That is, when the stack height fluctuates during the feeding operation, since the belt is seated on the stack due to its own weight, it automatically moves along with the stack to provide continuous and reliable feeding. Furthermore, according to the invention, the belt is not actively pushed into the stack by an external actuator and is not applied. As a result, the normal force is uniformly distributed over the plane of the sheet and no points of high pressure load are formed between the stack and the sheets for paper feeding.

Bonding forces between sheets are minimized because the forces directed down the stack are not so great that the sheets often become mechanically bound together.

The invention will be more fully understood from the following description of the drawings.

The apparatus of the invention is indicated generally by the numeral 10 in FIGS. The device is characterized by a cantilevered feed belt 12 which floats freely over a stack 14 of documents or paper sheets when the unsupported end is in the feed position (FIG. 2).

The feed belt 12 is connected to a drive pulley 16 which is spaced apart from the stack 14 in the configuration shown in FIGS.
It's being investigated above. A blocking member 18 is arranged between it and the stack 14. At the feed position,
The unsupported portion of the belt 12 also floats freely on the blocking member 18''.

In both figures, the feed belt 12 is wound around the drive pulley 16 by a second belt 20, which is guided by a system of three gooses 22.24 and 26 arranged against the drive pulley 16. and is driven by the drive pulley 16. Other wrapping or engagement devices may also be suitable. For example, belt 12 may be pressed against drive pulley 16 by one or more support rolls.

The feed belt 12 is moved between a non-feeding position (FIG. 1) and a feeding position (FIG. 2) by means of a positioning device a, which in the case of FIGS. 1 and 2 is an idler wheel 28.

In the non-feeding position of FIG. 1, the idle wheel 28 supports the feed belt 12 out of contact with the paper stack 14. In this position, it is desirable that the belt also not contact the stop to prevent wear. From the position shown in FIG. 1, the idler wheel 28 pivots or moves to the position shown in FIG. 2, where the belt 12 is unsupported and floats freely above the paper stack 14. Belt 12 is sufficiently stiff to retain the general shape shown in FIG. 2, but also sufficiently flexible to allow it to sag and impinge on paper stack 14 as shown, so that the height of the stack can be reduced. Adapt to fluctuations. It will be appreciated that the idle wheel 28 may be replaced by other isometric positioning devices.

In the feed position, the unsupported end of the belt 12 is connected to the paper stack 1.
4 It's on top. As the drive wheel 16 rotates the belt, the belt pulls paper sheets from the stack 14 and advances them past the blocking member 18 and into the delivery guide 30. The paper sheet, still in contact with belt 12, is guided by delivery guide 30 to a contact point 32 formed between a pair of pinch rollers 34 and 36. pinch roller 3
4 and 36 feed the sheets removed from the stack 14 to a processing device used in conjunction with this feeding device. As discussed in more detail below, the belt must be of sufficient size, weight, and stiffness to provide the necessary frictional force to advance the paper from the stack without bending or losing its alignment. Must be.

As previously mentioned, the feed belt 12 floats over the block 18 in the feed position. Although the blocking member 18 can take many shapes, sizes and arrangements, it is preferred that the blocking member 18 also include a resilient pad 40 with a curved leading edge.

Blocking member 18 functions in a manner described below to prevent more than one sheet from being fed into the processing device at the same time. It has been found that loosely stacked papers are easily fed by the feed belt 12 and no blocking mechanism is required. If the sheets are frictionally connected, separation is effected by the cooperative action of the feed belt and the blocking member.

Besides fixed pads, the blocking member can also take other forms, such as rollers, shoes, endless belts, etc. A suitable resilient material for the blocking member is a soft vulcanized rubber having a durometer rating of about 40. Suitable elastomers include polyurethane, poly(vinyl chloride), natural rubber, styrene-butadiene rubber, nitrile rubber, butyl rubber, etc.

U.S. Pat. No. 4,192,497 also teaches microporous elastomers having a hardness of at least 25 durometers suitable for this invention.

The feed belt 12 must be capable of providing the necessary frictional force to advance the sheets from the stack without losing their alignment. This means that the belt must be of minimum weight and stiffness depending on the size and weight of the sheets or documents to be fed. Preferably, the belt comprises a molded elastic material bonded to the surface of an inelastic woven substrate. Various kinds of materials can be made in Europe.

Dacron and rayon cords are suitable substrates.

The molded elastic material may be a conventional rubber formulation such as natural rubber, neoprene, styrene-butadiene rubber, polyacrylonitrile, and imprene. A preferred belt elastic material is the imprene rubber formulation disclosed in US Pat. No. 3,931,090, which contains polyisoprene, metal oxides, and fatty acids among other ingredients. The belt should be abrasion resistant and have the frictional properties described below.

Belt 12 has an annular length sufficient to convey sheets from stack 14 past blocking member 18 to the sheet transport device. Also, since the length of the belt does not affect the weight of the unsupported portion, the length of the belt can be one factor that is adjusted to provide the necessary frictional force. In other words, the frictional force acting on the seat is the belt normal force 4 on the seat.
Proportional to 4. This normal force is bell!・Equal to the weight of the unsupported part of That is, the portion of belt 120 that rests on stack 14 must be sufficient for the type of belt used to provide the necessary frictional force to advance the sheets. The following belt dimensions have been found to be satisfactory for belts with the preferred formulations described above.

Annular length 22 CTn (B,, Bn) thickness
0.318 cnl (0,125”) width
Typically, the coefficient of friction of a belt of such material against paper is on the order of about 17.

Unlike conventional devices, the device of the present invention uses induced thimbling (1st
uced shingling) or [fanning out] J is not used.

Individual sheet feeding is accomplished by the floating belt applying a normal force 44 uniformly over a large area of the stack 14. This prevents high pressure point loads from being transmitted downward through the top sheet of the stack and reduces mechanical coupling between sheets, which typically results in double and multiple feeds. However, if the second underlying sheet of paper is also advanced, the blocking member 40 exerts a frictional separation force.

It functions as a wiper. In order to function in this manner, the coefficient of friction of the surface of the blocking member against the paper must be higher than the coefficient of friction between sheets of paper (and lower than the coefficient of friction of the belt 12 against the paper). A paper hopper used as a paper hopper is equipped with a lifting device that responds to changes in the stack height or paper height within the hopper.

A typical lift control device includes a stack height detector 51, a speed controller 52, and a motor 5, as schematically illustrated in FIG.
3 and a cable assembly 54. If the lift control is good, the change in stack height relative to the belt is not significant, but some variation is always present.

Because the belt of this invention is free-floating above the surface of the stack, it readily accommodates such changes in stack height.
．． It can be used to feed a variety of paper types, including very thin paper weighing up to 8 kg (approximately 15 lbs.) to very thick paper weighing over 14 kg (32 lbs.).

If the sheet or document being fed has an unusually large area, more than one cantilever belt may be used.

Although the present invention has been described in detail with respect to specific configurations thereof, it will be appreciated by those skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the claims. It should be obvious.

[Brief explanation of drawings]

1 and 2 are schematic diagrams illustrating one configuration of the apparatus of the present invention, with the belt shown in the non-feeding position and the fed position, respectively. In these drawings, 10 is a sheet feeding device, 12 is a feeding vent, 14 is a stack of sheets, 16 is a drive pulley, 18 is a blocking member, 20 is a second belt, 22, 24
．． 26 is a pulley, 28 is an idle wheel (positioning device)
, 34 and 36 are pinch rollers, and 40 is a pad. Patent applicant: The Mead Corporation (4 others)

Claims (1)

Claims: (1) A sheet feeding device (10) for feeding individual sheets from a stack (14), having (12) an endless sheet feeding bell with a friction surface; (12) being cantilevered around a drive pulley (16) for drive rotation about an endless path; said bell in drive engagement with said drive pulley (16); ) (12) Belt holding device for holding (2)
0) and said cantilevered bell) (1, 2) are free floating in contact with said stack of sheets (14) and are frictionally engaged with the topmost sheet in said stack. a first position in which said belt (12) is supported by a movable positioning device (28) so as not to come into contact with said stack (14); A sheet feeding device as described above, characterized in that said movable positioning device (28) is provided for locating said belt. (2) positioned adjacent said stack in contact with said sheet transport belt in said first position for separating the topmost of said sheets from other sheets fed therewith; 2. The device according to claim 1, further comprising a blocking member (18). (3) a pair of pinch rollers (34, 36) are further provided, the belt pulling the topmost sheet in the stack past the blocking surface (42); ). Apparatus according to claim 2, adapted to be sent to: (4) The bell 1-(12) and the blocking member (1)
8) is formed of a resilient material which provides said belt with a coefficient of friction against paper that is greater than a coefficient of friction against paper of said blocking surface. (5) The device according to claim 1, wherein the positioning device (28) is an idle vehicle. (6) The belt holding device has a series of pulleys (22,
24, 26) second belt (20) mounted on
said series of pulleys are arranged relative to said drive pulley (16) so as to surround said feed belt (12) around a substantial portion of said drive pulley (16); Apparatus according to claim 1. (7) The device according to claim 3, further comprising a device for raising and lowering said stack of sheets. (8) Said blocking member (18) comprises a pad (40) with a curved leading edge.
Equipment described in Section. (9) The above-mentioned feed bell) (12) is the above-mentioned drive boo'
) (16) to at least the stack of said sheets (1
4). The device according to claim 1, wherein the device extends to the center of 4). 10. The device according to claim 1, wherein said positioning device (28) is arranged inside said endless path. an endless sheet conveying belt (12) with a friction surface, a blocking member (1) arranged adjacent to the stack of sheets (14) and in contact with said belt (12);
8) and a lifting device for adjusting the height of said stack so that the top of said stack is maintained in contact with said belt during subsequent sheet feeding operations. , in a sheet feeding device (10) for feeding individual sheets from a stack, said belt (12) is driven by a drive boo! such that said belt (12) is driven into rotation along an endless path. It is supported in a cantilevered manner around J (16) and is adapted to float above said stack and feed the sheets from thereon, and said bell I-(12) is held by a belt holding device (20). Said driving boo! The sheet feeding device as described above, wherein the sheet feeding device is held in driving engagement with J(16). (12) Said sheet feeding belt) A movable positioning device arranged inside said sheet feeding belt for lifting said sheet feeding belt (12) out of contact with said stacking (14) and said blocking member (18). 12. The device of claim 11, further comprising (28). (13) The belt holding device has a series of pulleys (22
, 24, 26) attached to the second belt (20
), said series of pulleys surround said drive boob IJ (12) around a substantial portion of said drive boob IJ (16). J(
Claim 11, arranged against 16)
The device according to item 1 or item 12.