JPH06100193A - Feeder - Google Patents

Abstract

(57) [Abstract] [Purpose] When the feed roller is fed to the pressure contact surface between the feed roller and the retard roller that receives a rotational force in the opposite direction from the feed roller via the torque limiter, when the sheets are separated and fed, Separately feed the sheet so that it does not become contaminated by the developer adhering to the sheet. [Structure] When a protrusion is provided on the surface of the retard roller and a plurality of sheets are about to be fed to the pressure contact surface between the conveying roller and the retard roller, the protrusion provided on the retard roller causes the sheet on the retard roller side to move. By locking and pushing back this sheet, a plurality of sheets are prevented from being pressed against each other at the pressing surface, and the occurrence of dirt on the sheets is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for feeding and feeding sheets, and more specifically, it separates and feeds sheets on which images are formed to prevent double feeding of sheets. Regarding the feeding device.

[0002]

[Prior art]

<Prior Art 1> An image forming apparatus such as a copying machine has heretofore been provided with an apparatus having a double-sided mode for forming an image on both sides of a sheet or a multiplex mode for forming a plurality of images on the same side. There is. FIG. 9 is a schematic cross-sectional view of the image forming apparatus, which includes an image forming unit 1, a sheet feeding unit 2 that feeds a sheet to the image forming unit 1, and an image of a sheet formed by the image forming unit 1. A fixing unit 3 for fixing the sheet, a sheet discharge unit 4 for discharging the sheet on which the image formation is completed, an intermediate tray 5 for temporarily storing the sheet once image-formed and fed to the image forming unit 1, a sheet to be re-fed Re-feed sheet guiding section 6 for guiding the sheet to the intermediate tray 5, and the intermediate tray 5
A sheet re-feeding unit 7 that re-feeds the sheets stored in the image forming unit 1 and a document replacement device 8 that places a document on the platen glass are arranged.

In the above structure, when the image forming apparatus selects the double-sided mode in which images are formed on both sides of the sheet or the multiplex mode in which images are formed on the same side a number of times, the sheet once image-formed by the image forming unit 1 is selected. When the image is fixed in the fixing section 3, the sheet is not ejected as it is, but is stacked and stored on the intermediate tray 5 by the re-feed sheet guide section 6, and when a predetermined number of sheets are stored, the sheet re-feed section 7 is used. The sheets are separated and fed one by one, and fed again to the image forming unit 1. Then, when the next document is placed on the document table by the document exchange device 8, a second image is formed, the image is fixed by the fixing unit 3, and then the sheet is discharged to the sheet discharge unit 4.

Further, as a method for separating and feeding the stacked sheets one by one like the sheet re-feeding section 7,
A plurality of sheets have been fed to a separation unit (not shown) by a retard roller (not shown) that receives a rotational driving force opposite to the conveying direction via a feed roller that rotates in the forward direction and a predetermined torque limiter. In this case, the retard separation system is generally used in which the sheet on the retard roller side is returned in the reverse direction and only the sheet on the paper feed roller side is fed.

As the double-sided sheet re-feeding system, the sheets on which the first side is image-formed are successively stacked on the intermediate tray 5, and the sheets in the lower part of the stacked sheets are separated and fed one by one. The lower separation method is known. In the image formation using the above method, the stacked sheets are separated one by one as described later. That is, FIG.
As shown in FIG. 2, the sheet stacked by hitting the intermediate tray 5 along the surface of the sheet stopper 13 is conveyed in the downstream direction by the half-moon roller 9 from the lowest sheet as shown in FIG. Then, the transport roller 10 that rotates in the transport direction
And a retard roller 11 that is brought into contact with the transport roller 10 and is driven by the transport roller 10 while receiving a rotational driving force opposite to the transport direction via a predetermined torque limiter.
The sheet is conveyed to the nip portion n formed by and. if,
When a plurality of sheets are fed to the nip portion n, the sheets on the retard roller 11 side are returned in the direction opposite to the conveying direction, whereby only the sheet on the conveying roller 10 side is separated and fed as shown in FIG. Then, it is sent to the image forming unit 1 by the pair of carrying rollers 12. <Prior Art 2> A prior art 2 will be described with reference to the drawings. FIG. 11 is a side view showing the schematic configuration of the image forming apparatus.
A document exposure light 20 is attached to a document placed on the document table 20c.
The image irradiated by a is an optical system 20 such as a lens and a mirror.
A latent image is formed on the photosensitive drum 20d through b. The latent image is visualized (toner image) by attaching the toner in the toner hopper 21a to the toner from the developing device 21b. The sheets fed from the sheet stacking means 29a, 29b, 29c are sent by the registration roller pair 28 in time with the toner image, and the toner image is transferred.
After that, the sheet is conveyed to the fixing device 23 via the conveying unit 22. In the fixing device 23, the toner is fixed on the sheet by heat and pressure fixing. The sheet on which the toner is fixed is discharged onto the discharge tray (or sorter) 24c by the discharge roller 24b.

On the other hand, when images are formed on both sides, after the image is fixed on one side of the sheet, the conveying direction is reversed by the reversing section 24a and the sheet is conveyed to the discharge gate device 25 described later according to the size of the sheet. Further, the sheet is sent to the sheet stacking unit 26 (where surrounded by the one-dot chain line). Then, after being stacked on the sheet stacking unit 26, the sheet is the second registration roller pair 27,
The toner image is transferred again by the registration roller pair 28, is transferred again by the transfer unit 22, is fixed by the fixing unit 23, and is discharged onto the tray 24c by the discharge roller 24b.

Further, a manual sheet feeding unit 40 capable of manually feeding a plurality of sheets is arranged above the sheet stacking means 29a capable of feeding a large amount of sheets. FIG. 12 is a top view of the manual paper feeding unit 40. 10 to 14
2, the manual feed unit 40 is a tray 41 made of a resin material for stacking sheets, and a supporting plate 42 is fixedly provided on the tray 41, and the supporting plate 42 fixes the manual feeding unit 40 to the apparatus main body. To be done. A feed roller 43 is rotatably provided so as to be supported by the support plate 42, and a retard roller 44 is provided so as to face the feed roller 43. This retard roller 44
Is pressed against the feed roller 43 by urging means (not shown). A transmission member 45 such as a gear for transmitting the driving force from the apparatus body is provided at one end of the shaft of the feed roller 43. A support plate 47 is rotatably provided on the shaft of the feed roller 43, and a pickup roller 46 for feeding a sheet to the roller pair of the feed roller 43 and the retard roller 44 is rotatably provided. ing. Then, a pulley 49 integrally formed with a sleeve (not shown) fitted in the feed roller 43.
Is transmitted to the pickup roller 46 via the belt 50. Further, the pickup roller 46 moves up and down at the timing of paper feeding. This up-and-down movement is caused by ON / OFF control of the support plate 47 by drive means (not shown) such as a solenoid via the lever 51.

Further, the tray 41 is provided with a pair of side guides 52 which are movable according to the sheet size.
The pair of side guides 52 are designed to cooperate with each other by a rack built in the tray 41 and a pinion gear. Further, the tray 41 has an upper cover 53 having a shaft portion 53a.
Is rotatably supported around the auxiliary tray 54 and the auxiliary tray 54 is
It is rotatably supported by 4a. As shown in FIG. 14, a paper stopper 55 is provided on the upper cover 53 and a shaft portion 55a.
A Corui spring 56 is provided between the upper cover 53 and the paper stopper 55 to urge the paper stopper 55 counterclockwise.

When the manual feed unit 40 is not used, the auxiliary tray 54 is bent around the shaft portion 54a and placed on the upper cover 53 as shown in FIG. Has been done. When the manual feed unit 40 is used, the auxiliary tray 54 is unfolded as shown in FIG. 12, and then the upper cover 53 is opened in the arrow direction. The upper cover 53 is provided with locking means (not shown) that maintains the released state at a predetermined open position. Note that when the upper cover 53 is opened upward, the coil spring 56
The one end of the paper stopper 55 urged by means of this comes into contact with the stacking surface of the tray 41. After that, the coil spring 56 is simply twisted.

After the above operation, the sheet is placed on the tray 41, pushed in until the leading edge of the sheet hits the sheet stopper 55, and the side guide 52 is moved along the sheet width to set the sheet placing position. regulate. afterwards,
When the upper cover 53 is closed, the paper stopper 55, which is in contact with the stacking surface of the tray 41, is separated from and in contact with the tray 41, and the sheet can be fed.
Further, a micro switch (not shown) for detecting that the upper cover 53 is closed is provided on the tray 41, the upper cover 53 is open, and the paper stopper 55 is in contact with the stacking surface of the tray 41. It cannot be fed as it is.

[0011]

[Problems to be Solved by the Invention]

<Problem of the first invention> However, in the conventional technique 1, when a plurality of sheets are conveyed to the nip portion n, a sheet positioned above the lowest sheet (upper sheet) is also nipped in the nip portion. Therefore, the portion corresponding to the nip portion n of the upper sheet is inspected while being pressed against the lowermost sheet. If images are formed on both sides, the nip portion n on the back side of the upper sheet is partially soiled, and if images are to be formed in multiple layers, the upper surface of the upper sheet is thin and streaky stains are attached. There was a problem.

The cause of this stain generation will be described using a simple model shown in FIGS. FIG. 15 is a model showing a state in which multiple images are formed, and black dots g represent toner in the image. When the sheet is fed while being separated at the nip portion n at the time of re-feeding, when the leading edge of the upper sheet enters the nip portion n, the upper sheet is pressed against the lowermost sheet by the pressure contact force of the roller pair 10 and 11. Therefore, the leading end portion of the upper sheet is pressed against the lowermost sheet at the nip portion n and is inspected. At this time, the toner at the tip of the upper sheet peels off and adheres to the back surface of the lowermost sheet (the image side is the front side), and the surface of the lowermost sheet becomes thinly streaked and the image of the leading edge of the upper sheet is imaged. Will fade.

When images are formed on both sides as shown in FIG. 16, when sheets are fed at the time of re-feeding as in the case of multiple sheets, the upper sheet is detected as the lowermost sheet and the toner of the lowermost sheet is detected. Attached to the back surface of the upper sheet, tip nip n
Is partially soiled.

Therefore, it is an object of the first invention to provide a sheet feeding device which prevents double feeding of sheets and prevents the sheets from being soiled or the image becoming thin. <Problem of the Second Invention> In Prior Art 2, after the sheet is placed on the manual feed unit 40, the upper cover 53 is placed.
Even if is closed, the trailing edge of the sheet is exposed from the auxiliary tray 54, and the user may press the trailing edge of the sheet to confirm the sheet position just before the image formation. As described above, when the rear end of the sheet is pushed after the upper cover 53 is closed, the leading end of the sheet is pushed into the roller pair of the feed roller 43 and the retard roller 44, and as a result, the sheet is double-fed. Or it was causing a jam.

Therefore, in the second invention, when the sheet is placed, the sheet is fed by the feed roller 43 even if the rear end of the sheet is pushed.
It is an object of the present invention to provide a sheet feeding device capable of preventing double feeding of sheets and occurrence of jam by preventing the roller pair of the retard roller 44 from reaching the roller pair.

[0016]

A conveyance rotary body (10) for conveying a sheet is pressed against the conveyance rotation body (10) while receiving a rotational driving force opposite to the conveyance direction via a torque limiter, And a retard rotating body (11) driven by the conveying rotating body (10), and a plurality of sheets are conveyed to a pressure contact surface between the conveying rotating body (10) and the retard rotating body (11). When this occurs, the torque limiter operates, the retard rotating body (11) rotates in the direction opposite to the conveying direction, and the sheet on the retard rotating body (11) side is pushed back to prevent double feeding of sheets. In the feeding device configured as above, the surface of the retard rotary body (11) is made of an elastic body, and a large number of protrusions (11b) are provided on the surface, and the protrusions (11b) are the rotary conveyor (10). ) Seats other than Made to prevent double feeding of the sheet engaged locks in, characterized in that.

For example, the protrusion height (s) of the protrusion (11b) provided on the surface of the retard rotating body (11).
Is set to be equal to or larger than the thickness of the sheet.

Further, in the feeding device for placing a sheet on the surface of the sheet placing table (40) and manually feeding the sheet, the surface of the placing table described above is opened when the sheet is placed, and the sheet placed after the sheet is placed. And a cover (62) for covering.

Further, the cover (62) is slidably provided on the sheet mounting table (40), and when the sheet is mounted, the cover (62) is slid to open the surface of the stacking table (40), After the sheet is placed, the placed sheet is slid so that the cover (62) covers it.

Further, when the cover (62) opens the surface of the sheet placing table (40), the leading end portion of the sheet to be placed is restricted, and the sheet placed with the cover (62) closed is set to the above-mentioned state. When the cover (62) covers, it has a regulation means (55) in which regulation of the sheet front end portion is released.

[0021]

[Action]

<Operation of the First Invention> According to the present invention, a plurality of protrusions are provided on the surface of the retard roller (11) in pressure contact with the conveying roller (10), and a plurality of sheets are locked to the protrusions and the pressure contact surface is formed. By preventing a plurality of sheets from being sandwiched between the sheets, it is possible to prevent the sheets from being double-fed, and to prevent the sheets from being contaminated due to the sliding friction of the pressure contact surface. <Operation of Second Invention> According to the present invention, the cover (6) which can cover the entire surface of the sheet is provided on the manual feed unit (40).
2) is provided, and when the cover (62) is opened and the sheet is placed, the leading end portion of the sheet is regulated, and when the cover (62) is closed, the regulation of the leading end portion of the sheet is released (55). ) Is provided to prevent double feeding of sheets and occurrence of jam.

The reference numerals in each of the above-mentioned items are for the purpose of contrasting with the drawings, but do not limit the structure of the present invention.

[0023]

【Example】

<First Embodiment of the Invention> The present invention will be described below with reference to the accompanying drawings. Since the basic structure of the image forming apparatus is substantially the same as that of the conventional technique 1, the same reference numerals are given and only different points will be described.

FIG. 1 shows a lower separation type sheet re-feeding unit using a retard roller, which is a conveying roller 10 (feeding rotary member) for conveying a sheet in the downstream direction (right side in FIG. 1) and a retard roller 11 ( Retard rotator).
The conveying roller 10 has a surface made of an elastic body 10a such as rubber and is rotationally driven in the direction of arrow a, and the rotor roller 11 is in a direction opposite to the conveying direction (direction of arrow b) via a torque limiter (not shown). While receiving the rotational driving force of
It follows (rotates in the direction of arrow c when rotating together). The surface is made of the elastic body 11a. On the other hand, as shown in FIG. 1, the retard roller 11 has a protrusion 11b on the entire surface, and the step s of the protrusion 11b is slightly larger than the thickness t of the sheet.

With this configuration, the stacked sheets are separated and fed one by one as described below. That is, the sheets stacked by hitting the intermediate tray 5 along the surface of the sheet stopper 13 as shown in FIG. 10 are conveyed downstream from the lowest sheet by the half-moon roller 9 as shown in FIG. Then, a transport roller 10 that is rotationally driven in the transport direction, and a retard roller 11 that rotates while being contacted with the transport roller 10 while receiving a rotational driving force opposite to the transport direction via a predetermined torque limiter.
Is conveyed to the nip portion n formed by.

When a plurality of sheets are conveyed, the second and subsequent sheets are locked by the protrusions 11b of the retard roller 11 as shown in FIG. 1, and
It is pushed back in the opposite direction. In other words, unlike the conventional example, the second sheet is always held in the nip portion n and pressed against the first sheet, and thus the double feeding of the sheets is not blocked. By making contact with the protrusion 11b, double feeding is prevented. Therefore, the first sheet is not conveyed while being pressed by the second sheet. That is, it is possible to prevent the occurrence of stains on the sheets due to the rubbing between the sheets as shown in FIGS. in this way,
The sheet on the retard roller 11 side is returned in the opposite direction while being blocked by the protrusion 11b, and eventually only one sheet on the transport roller 10 side is separated and fed as shown in FIG. Sent to Part 1.

The step s of the protrusion 11b may be equal to or larger than the thickness of the sheet, but the outer diameter d of the retard roller 11 is not limited to this.
Was 32 [mm], good results could be obtained in the range of s = 0.3 to 3 [mm].

In this embodiment, the shape of the protrusion as shown in FIG. 1 has been described, but the present invention is not limited to this, and the same effect can be obtained even if the shape is as shown in FIG. Becomes <Embodiment of the Second Invention> The present invention will be described below with reference to the accompanying drawings. Since the basic configuration of the image forming apparatus is substantially the same as that of the conventional technique 2, the same reference numerals are given and only different points will be described.

In FIG. 5, an upper cover 61 of the manual feed unit 40 (sheet mounting table) is rotatably supported on the tray 41 by a shaft portion 61a. Also, this top cover 6
1, an auxiliary upper cover 62 is provided, and shaft portions 62a protruding at both ends are fitted into grooves 61b provided on both sides of the upper cover 61, whereby the auxiliary upper cover 62 is provided.
The (cover) can slide to the right (to the right in FIG. 5). When the sheet is fully pulled out to the right, the entire sheets stacked on the auxiliary tray 54 can be covered.

A shaft portion 60a is arranged on the upper cover 61 coaxially with the shaft portion 61a, and a paper stopper 60 (regulating means) is pivotally supported so as to be rotatable around the shaft portion 60a. Then, it is urged to rotate clockwise by an urging member (not shown) such as a coil spring.

In the above structure, when the manual feed unit 40 is not used, the auxiliary tray 54 and the auxiliary upper cover 62 are housed on the upper cover 61 as shown in FIG. At this time, the paper stopper 60 is projected on the sheet stacking surface in such a manner that the projection 60b is pushed by the auxiliary upper cover 62. When the hand unit 40 is used, the auxiliary tray 54 is first rotated to the state shown in FIG. 5, and then the upper covers 61 and 62 are both opened upward as shown in FIG. To load. At this time, lock means (not shown) for fixing the upper cover 61 to the open position is provided. Then, after closing the upper cover 61, the auxiliary upper cover 62 is slid to the right to release the pressing force of the auxiliary upper cover 62 against the protrusion 60b of the paper stopper 60, and the sheet is loaded as shown in FIG. Evacuate above the placement surface. At the same time, the auxiliary upper cover 62 can cover the entire surface of the sheet on the auxiliary tray 54.

With the above construction, when the auxiliary upper cover 62 can slide to the right after the sheets are stacked, the image forming operation cannot be performed because the paper stopper 60 is in contact with the sheet mounting surface. For this reason, in order to detect that the auxiliary upper cover 62 is securely closed before the image forming operation is started, as shown in FIG.
A micro switch 64 and a rotatable detection lever 63 are provided so that the protruding end of the detection lever 63 becomes the opening 61c of the upper cover 61 and projects. When the auxiliary upper cover 62 is slid, the auxiliary upper cover 62 turns on / off the lever protruding from the opening 61c of the upper cover 61.
You may make it detect by setting. And
This detection switch position may be provided separately from the switch for detecting the opening of the upper cover 61 similar to that in the conventional device.

[0033]

【The invention's effect】

<Effect of the First Invention> As described above, according to the present invention, even if a large number of sheets try to enter the pressure contact surface between the transport roller and the retard roller by providing a plurality of protrusions on the retard roller, The protrusions prevent the sheets other than those on the conveying roller side from locking and preventing this, so that the rubbing between the sheets on the pressure contact surface is prevented and the occurrence of stains on the sheets can be prevented. <Effect of Second Invention> As an effect of the second invention, the manual feed unit is provided with a cover capable of covering the entire surface of the sheet, and when the cover is opened and the sheet is placed, the leading end portion of the sheet is By providing the regulation means that regulates and releases the regulation of the sheet front end portion when the cover is closed, even an inexperienced operator can prevent the sheet from being double-fed or jammed.

[Brief description of drawings]

FIG. 1 is a side view of a feeding unit of a feeding device applied to an embodiment of the first invention.

FIG. 2 is an explanatory view of the feeding principle of the feeding device applied to the embodiment of the first invention.

FIG. 3 is an explanatory view of the feeding principle of the feeding device applied to the embodiment of the first invention.

FIG. 4 is a side view of a feeding unit of the feeding device applied to the embodiment of the first invention.

FIG. 5 is a side view of a manual feeding unit applied to the embodiment of the second invention.

FIG. 6 is a side view of a manual feeding unit applied to the embodiment of the second invention.

FIG. 7 is a side view of a manual feeding unit applied to the embodiment of the second invention.

FIG. 8 is a side view of a switch portion of the manual feed unit applied to the embodiment of the second invention.

FIG. 9 is a side view of the image forming apparatus applied to the description of the related art 1.

FIG. 10 is a feeding principle diagram of a feeding device applied to the description of the related art 1.

FIG. 11 is a side view of the image forming apparatus applied to the description of the related art 2.

FIG. 12 is a top view of a manual feed unit applied to the description of conventional technique 2.

FIG. 13 is a side view of a manual feed unit applied to the description of the related art 2.

FIG. 14 is a side view of a manual feed unit applied to the description of the related art 2.

FIG. 15 is a side view of the feeding device for explaining the problems of the conventional technique 1.

FIG. 16 is a side view of a feeding device for explaining the problems of the conventional technique 1.

[Explanation of symbols]

 10 Conveyance Roller (Conveying Rotating Body) 11 Retard Roller (Retarding Rotating Body) 11b Projection 40 Manual Feeding Unit (Sheet Placement Table) 60 Paper Stopper (Regulating Means) 62 Auxiliary Upper Cover (Cover)

Claims (5)

[Claims] 1. A conveyance rotating body which conveys a sheet, and a retard rotation which is pressed against the conveyance rotating body while receiving a rotational driving force opposite to a conveying direction through a torque limiter and is driven by the conveyance rotating body. When a plurality of sheets having a body are conveyed to the pressure contact surface between the conveyance rotating body and the retard rotating body, a torque limiter works, and the retard rotating body moves in a direction opposite to the conveying direction. In a feeding device that rotates and pushes back the sheet on the side of the retard rotating body to prevent double feeding of sheets, a surface of the retard rotating body is made of an elastic body and a large number of protrusions are provided on the surface. The sheet feeding device is characterized in that the projecting portion locks a sheet other than the sheet on the conveying rotary member side and pushes back the sheet material to prevent double feeding of the sheet. 2. The feeding device according to claim 1, wherein the protrusion height of the protrusion provided on the surface of the retard rotary member is set to be equal to or larger than the thickness of the sheet to be fed. 3. A sheet feeding device for placing a sheet on a surface of a sheet placing table and manually feeding the sheet, the cover for opening the surface of the placing table when the sheet is placed, and for covering the placed sheet after the sheet is placed. A feeding device comprising: 4. The cover is slidably provided on the sheet mounting table, and when the sheet is mounted, the cover is slid to open the stacking table surface, and after the sheet is mounted, the mounted sheet is covered by the cover. The feeding device according to claim 3, wherein the feeding device is slid so as to cover. 5. The sheet mounting table has a restricting means for restricting the leading end portion of the sheet in association with the movement of the cover, and when the cover opens the surface of the sheet mounting table, the restricting means When the front end portion of the sheet to be placed is regulated and the cover is covered with the cover closed,
5. The feeding device according to claim 3, wherein the regulation unit releases the regulation of the sheet leading end portion to feed the placed sheet.