JP2840636B2 - Paper feeder for image forming equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for an image forming apparatus such as an electrostatographic copying machine or a printer.

[Conventional technology]

For example, in an electrostatographic copying machine, a device that feeds an uncopied sheet one by one to a transfer unit each time a paper feed signal is input, or a two-sided copy that refeeds a sheet after one-sided copying to a transfer unit. Sheet feeder for feeding a sheet document to a predetermined position on the platen every time a paper feed signal is input to the document feeder (DF) or from the intermediate tray There is.

As such a paper feeder, a double feed prevention type in which a double feed prevention member such as a friction pad or a pad roller is disposed in contact with a rotating paper feed member to prevent double feeding of sheets by so-called friction separation, A part of the pad roller and the rotating sheet feeding member are superposed and arranged, and the sheet is corrugated between the two members so as to prevent the sheet from being fed twice by utilizing the so-called stiffness of the sheet. There is a double feed prevention type.

[Problems to be solved by the invention]

By the way, in the above-described sheet feeding device, at the time when the image forming operation is completed, the sheet for which double feed prevention has been performed is fed from a sheet storage unit such as a sheet feeding cassette or a sheet feeding deck. Is located near (residual to) the double feed prevention member formed by the double feed prevention member and the rotary sheet feeding member, and is sometimes sandwiched between the double feed prevention portions.

In such a state, when the sheet cassette is pulled out or the sheet mounting plate of the sheet deck is lowered to replenish sheets to the sheet cassette or the sheet deck, the double feed is prevented. The sheet remains in the double feeding prevention unit, and when the sheet feeding cassette or the sheet feeding deck is set next time, the sheet remaining in the sheet feeding unit is crushed and wasted, and the crushed sheet is lost. There is a problem that a jam occurs due to the sheet that has been damaged.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned inconvenience caused by the position of a sheet at the double feed prevention unit.

[Means for solving the problem]

According to the present invention, in order to achieve the above-described object, a first rotating paper feeding member, a second rotating paper feeding member downstream of the first rotating paper feeding member in a paper feeding direction, and a double feeding preventing member are provided. A double feed prevention unit which constitutes a feed prevention unit; and a sheet return movably provided from a downstream side to an upstream side of the double feed prevention unit for returning a sheet located near the double feed prevention unit to the sheet storage unit. A member, first sheet return means for moving the sheet return member in the sheet return direction in response to a predetermined sheet return signal, and A sheet feeding device for an image forming apparatus, comprising: a second sheet returning device that is driven to rotate in a reverse direction. Provided via anti-feeding Only made rotatable pad roller countercurrent, the sheet feeding device of an image forming apparatus is provided, characterized in that and is provided with the seat back member to the reciprocating rotation shaft.

[Action]

According to the present invention, when a sheet return signal is transmitted, the sheet return member moves in the sheet return direction,
The first and second rotating paper feed members rotate in the sheet return direction,
The sheet located near the double feed prevention unit is returned to the sheet storage unit.

The above-mentioned sheet return signal is, for example, a detection signal of the end of the image forming operation, a signal for replenishing the sheet to the sheet storage unit, or a lowering of the sheet storage unit of the sheet mounting plate in the inside for replenishing the sheet. It is transmitted based on a detection signal or the like of a descending operation of the sheet storage unit when moving.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic view of a two-sided copying machine showing an example of an image forming apparatus, in which a document holder 2 provided with an automatic document feeder 1 is disposed in a copying machine main body 3 and a photosensitive member 4 In addition, a charging device 5, a developing device 6, a transfer device 7, a sheet separating device 8, and a cleaning device 9 are sequentially arranged, and an optical system movable exposure device 10 is provided in an upper space of the copying machine main body 3.
And a second transport device 15 that transports the sheet in the manual feed unit 11 or the paper feed cassette 12 to the transfer device 7, and a second transport device 15 that transports the transferred and separated sheet to the fixing device 14. And a discharge roller pair 17 for discharging the fixed sheet to the tray 16.

Then, an intermediate tray 18 for stacking sheets after one-sided copying is arranged in a lower space of the copying machine main body 3 and a double feed preventing sheet feeding device 19 is provided in a re-feeding section of the intermediate tray 18.
And a switchback mechanism 20 for selectively discharging the fixed sheet to the intermediate tray 18, and for re-feeding the paper from the double feed preventing paper feeder 19 to the transfer device 7. A transfer device 21 is provided.

Further, an elevator-type paper feed deck 22 capable of storing a large amount of sheets is provided below the arrangement portion of the paper feed cassette 12, and the sheets stored in the elevator type paper feed deck 22 are re-fed. A double feed prevention device 23 for merging with a transfer device 21 is provided.

Thus, a single-sided copying mode in which an image is transferred to one side of a sheet fed from the manual feed unit 11, the sheet cassette case 12, or the sheet feeding deck 22, and the single-sided copy sheet is discharged to the tray 16 An image is formed on the back side of the single-sided copied sheet fed from the intermediate tray 18 at a predetermined timing, and the double-sided copying mode of discharging the double-sided copied sheet to the tray 16 is selected. I can do it.

Next, the multi-feed prevention paper feeder 23 in the paper feed deck 22
Will be described.

As shown in FIG. 1 and FIGS. 3 to 5, the double feed preventing sheet feeding device 23 feeds a pair of upper and lower sheet feeding guides 24 and 25 having openings a and b respectively to the sheet feeding deck 22. A part of a rubber paper feed roller (constituting a second rotating paper feed member) 26 having a plurality of roller portions c and being provided on the paper portion is moved downward from the opening a of the paper feed guide 24 on the upper side. And a rubber double-feed prevention pad roller (constituting a double-feed prevention member) having a plurality of roller portions d.
Is arranged so as to protrude upward from the opening b of the lower sheet feeding guide plate 25 in a state of being superposed on the roller portion c, and is advanced by a forward feed roller (constituting the first rotating sheet feeding member) 28. Both rollers are used when the fed-out sheets are stacked
When the sheet is fed to the wavy path of 26, 27, the leading end of the sheet on the pad roller 27 side is brought into contact with the pad roller 27 side to feed only the sheet on the sheet feeding roller 26 side (upper side). It is made to let. That is, a part of the rollers 26 and 27 is overlapped in a wave shape to constitute a double feed prevention unit for preventing the sheet from being fed twice.

Then, the pad roller 27 with respect to the paper feed roller 26
(A part of the roller portions c and d of both rollers 26 and 27 is overlapped and arranged when both rollers 26 and 27 are overlapped as described above.)
a mechanism 29, which can adjust the overlap dimension of c and d) and the gap allowance (the gap dimension between the end faces of the two roller portions c and d when the two roller portions c and d are partially overlapped). A drive means 31 is provided to rotate the pad roller 27 by a predetermined angle in a direction opposite to the sheet feeding direction, so as to suppress uneven wear of the double feed prevention roller 27 in the double feed prevention unit. When a detection signal of a lowering operation when lowering the paper loading plate 22A inside the paper feeding deck 22 for replenishing the sheet is issued, the sheet positioned near the double feeding prevention unit is fed. First sheet returning means 55 for returning to deck 22
Are configured using the drive system of the drive means 31 (to be described in detail later).

In detail, the rotating shaft 47 provided with the paper feed roller 26,
It is supported by brackets 33, 33 provided continuously to the copying machine main body 3, and is driven and connected in the sheet feeding direction at a predetermined timing via a motor M1 and gears 53, 54.

On the other hand, the pad roller 27, the overlap margin and gap margin adjustment mechanisms 29, 30 and the drive means 31 are unitized and configured as follows. That is, a pair of brackets 35, 35 are cut and raised on a rising plate portion 34a of a base 34 mounted and fixed on the copying machine main body 3, and are continuously provided.
The bracket 35, 35 is pivotally connected to the brackets 35, 35 via a support shaft 36 parallel to the pad roller 27, and the holding member 37 is connected in the axial direction.
38, and at one end of the reciprocating rotary shaft 38,
The pad roller 27 is provided via one-way transmission means 39 which allows only rotation in the direction opposite to the sheet feeding direction.

Then, the screw shaft e is inserted through the rising plate portion 37a of the holding member 37 and the rising plate portion 34a of the base 34.
And a screw member f is screwed onto the screw shaft e,
In addition, a biasing means 41 composed of a compression coil spring is interposed between the two rising plate portions 37a, 34a, so that the support shaft 36 of the holding member 37 is rotated by rotating the screw member f.
It is configured such that the margin of overlap of the pad roller 27 with respect to the paper feed roller 26 can be adjusted by swinging around.

Further, a screw portion g is formed on one end side of the support shaft 36, and a screw member h is screwed to the screw portion g, so that the support shaft 36 can be freely moved in one axial direction. Urging means for applying an urging force in the anti-screw direction to the holding member 37
42 is interposed between the bracket 35 and the holding member 37, so that the spindle is rotated by rotating the screw member h.
By moving the holding member 37 in the axial direction of 36, the clearance of the pad roller 27 with respect to the paper feed roller 26 can be adjusted.

Further, a sheet return member 43 made of relatively hard resin (for example, polyacetal) is fixed to the reciprocating rotation shaft 38 on both sides of the pad roller 27, and a worm is attached to the other end of the reciprocation rotation shaft 38. A motor M1 having a worm G2 fixed to the wheel G1 and meshing with the worm wheel G1 is attached to the holding member 37, and the motor M1
The sheet return member 43 can be reciprocally rotated (moved) by the forward / reverse rotation of.

Note that the sheet return member 43 is provided with the reciprocating rotation shaft thereof.
The dimension from the rotation center to the free end of 38 is larger than the radius of the pad roller 27, and the free end has a curved surface, and the free end does not come into contact with the rotating shaft 47. Set to length.

Here, the motors M1 and M2 are provided with a reciprocating rotation control unit 46.
Are electrically connected, and are based on a detection signal of a lowering operation of the paper loading plate 22A by a level switch (see FIG. 2) S1 for detecting a level of the paper loading plate 22A in the paper feeding deck 22. The sheet return signal transmitted in the
, The first sheet return means 55 is driven.
That is, the motor M1 is driven to rotate in the reverse direction a predetermined number of times.
The worm wheel G1, the worm G2, and the motor are controlled so that the worm wheel G1 and the worm G2
The driving means 31 for reciprocatingly rotating the reciprocating rotation shaft 38 over substantially one rotation is constituted by M1.

On the other hand, when a sheet return signal is similarly input to the control unit 46, the second sheet return means 56 is driven. That is, the motor M2 is reversely rotated a predetermined number of times. As a result, the feed roller 26 and the feed roller 28 that is driven and transmitted from the rotary shaft 47 via the ladder chain 57 are rotated in the reverse direction via the gears 53 and 54 and the rotary shaft 47.

Therefore, the first sheet returning means 55 and the second sheet returning means 56 operate as follows.

That is, as shown in FIG. 6, the sheet return member 43 is rotated integrally with the reciprocating rotation shaft 38 in the direction opposite to the sheet feeding direction.
The sheet return member 43 protrudes upward from the opening b on the downstream side of the double feed unit, moves over the upstream side of the double feed prevention unit, and is integrated with the rotation shaft 47, and the sheet feed roller 26, and By the reverse rotation of the forward feed roller 28 that is transmitted by the rotation shaft 47, even if a sheet remains near the double feed prevention unit, the sheet can be returned to the sheet feeding deck 22, Accordingly, when the sheet stacking plate 22A is lowered to replenish the sheets and the sheet stacking plate 22A is raised to a predetermined position, the sheet located near the double feed prevention unit is crushed. Or the occurrence of a jam due to the sheet can be prevented.

Thereafter, the sheet return member 43 is integrally rotated with the reciprocating rotation shaft 38, is rotated forward to return to the initial position, and waits for the next sheet return.

Thus, each time the sheet feeding deck 22 is lowered, the reciprocating rotation shaft 38 is reciprocated and rotated, and the pad roller 27 is moved only in the reverse sheet feeding direction with the reciprocating rotation of the reciprocating rotation shaft 38. By performing less than one rotation, uneven wear of the pad roller 27 is prevented.

A sensor S for detecting the occurrence of a jam between the double feed prevention unit and the pair of conveying rollers 44 is provided immediately downstream of the double feed prevention unit.

In the embodiment, the free end of the sheet return member 43 is configured not to abut on the rotating shaft 47. However, as shown in FIG. 7, the sheet return member 43 is thin and elastically deformed. An easy configuration may be adopted in which the free end portion is brought into contact with the rotating shaft 47 when the double feed prevention portion moves from the downstream side to the upstream side.

Further, in the embodiment, the sheet feeding deck 22 is used as a sheet accommodating section, and a double feed preventing sheet feeding apparatus for the sheet accommodating section is used.
Although 23 has been described, it is also possible to implement the sheet feeding unit of the manual feeding unit 11 or the sheet feeding cassette 12 or the intermediate tray 18 for re-feeding for double-sided copying as the sheet storage unit.
Further, the present invention is not limited to a copying machine, and it is also possible to apply a sheet feeding device in various image forming apparatuses such as a printer and a facsimile.

Further, a sheet return signal for moving the sheet return member 43 in the sheet return direction is transmitted based on a detection signal of a descending operation of the sheet mounting plate.
It is possible to make a change such as transmitting a sheet return signal based on a sheet replenishment signal or the like to the sheet storage portion or by detecting a jam with the sensor S described above. [Effects of the Invention] As described above, according to the present invention, a sheet which has been prevented (is left) in the vicinity of the double-feed preventing portion can be returned to the sheet accommodating portion. In addition, it is possible to reliably prevent the sheet located in the vicinity of the double feed prevention unit from being crushed or jammed due to the sheet.

[Brief description of the drawings]

FIG. 1 is a side view of a multi-feed prevention sheet feeder, FIG. 2 is a schematic longitudinal sectional view of an electrostatographic copying machine according to an embodiment of an image forming apparatus, and FIG.
FIG. 4 is a front view of the multi-feed prevention paper feeder, FIG. 4 is a plan view of the double-feed prevention paper feeder in which a rotary paper feed member is developed and shown, and FIG. Side view of the
FIG. 6 is an explanatory view of the operation, and FIG. 7 is a side view of a main part showing another embodiment of the sheet returning member. 11,12,18,22 ... sheets (manual feed section, intermediate tray, paper feed deck), 26 ... second rotary paper feed member (paper feed roller),
28: first rotating sheet feeding member (forward feed roller), 27: double feed preventing member (pad roller), 31: driving means, 38: reciprocating rotary shaft, 39: one-way transmission means, 43 ... sheet return member, S ... jam detection sensor.

Claims (4)

(57) [Claims] A double feed prevention unit comprising a first rotary paper feed member, a second rotary paper feed member downstream of the first rotary paper feed member in the paper feed direction, and a double feed prevention member. A sheet return member movably provided from a downstream side to an upstream side of the double feed prevention unit for returning a sheet located near the double feed prevention unit to the sheet storage unit, and a predetermined sheet return signal. First sheet return means for moving the sheet return member in the sheet return direction; and second driving means for rotating the first and second rotary sheet supply members in a direction opposite to the sheet conveyance direction by a predetermined sheet return signal.
A sheet feeding device for an image forming apparatus, comprising a sheet returning unit, wherein the double feed preventing member is provided with a reciprocating pivot shaft reciprocally rotatable and a re-feeding member provided on the reciprocating pivot shaft via a one-way transmission unit. A sheet feeding device for an image forming apparatus, comprising: a pad roller rotatable only in a paper direction; and the sheet return member provided on the reciprocating rotation shaft. 2. The sheet feeding means of an image forming apparatus according to claim 1, wherein said sheet return signal is transmitted based on a detection signal of a descending operation of a sheet mounting plate in a sheet storage section. 3. The sheet feeding device according to claim 1, wherein the sheet return signal is transmitted based on a detection signal indicating completion of an image forming operation. 4. The sheet feeder of an image forming apparatus according to claim 1, wherein said sheet return signal is transmitted based on a sheet supply signal to a sheet storage section.