JP2001088946A - Double face unit for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent failure in feeding transfer paper at paper refeeding without generation of skew. SOLUTION: This unit is provided with a pair of movable side fences 7, 8 and a movable end fence 43 to regulate a position of the transfer paper P in a double face tray 2 to be a specified position adequate for paper refeeding. This unit is also provided with a control device 60 to move the side fences 7, 8 to a stand-by position apart from a side edge of the transfer paper P while moving the end fence 43 to a stand-by position apart from a rear end edge of the transfer paper P before a bottom plate 15 is raised at the time of starting the paper refeeding. The side fences 7, 8 are thereby prevented from giving sliding resistance against the transfer paper P where the end side is raised.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided unit of an image forming apparatus provided with a double-sided tray for temporarily storing a transfer sheet for forming an image again on a transfer sheet having an image formed on one side.

[0002]

2. Description of the Related Art For example, an electrophotographic image forming apparatus such as a copying machine or a printer is provided with a double-sided tray for temporarily storing transfer paper on which an image is formed on one side in order to form an image thereon again. Some have double-sided units.

FIG. 12 shows an example of a color copying machine having such a duplex unit. This color copier includes an optical system 72 at an upper portion of an apparatus main body 71, and a paper feeding section in which paper feeding cassettes 73A, 73B, and 73C are arranged at three lower levels. Is provided with an image forming unit 74 for forming an image. Further, a duplex unit 75 is provided below the image forming unit 74.

The duplex unit 75 includes a duplex tray 7
A pair of side fences 77 and 78 for regulating both side edges of the transfer paper P fed onto the paper 6 at a predetermined position, and an end fence 7 for regulating the rear end of the transfer paper P in the feed direction to a predetermined position.
9 and a bottom plate 81 serving as a transfer paper pressing member that pushes up the leading end side of the transfer paper P on the double-sided tray 76 and presses the transfer paper P against the feed roller 80 to enable refeeding.

In this color copying machine, when the image forming operation is started by selecting double-sided image formation, the transfer paper P corresponding to the selected size is selected from one of the paper feed cassettes 73A, 73B, 73C of the paper feed section. Is supplied to the image forming unit 74.
Thus, an image is formed on the upper surface in FIG. The transfer paper P
Is conveyed to the double-sided unit 75 side by the branching unit 82, and is discharged onto the double-sided tray 76 of the double-sided unit 75 with the image surface facing upward, and temporarily stored therein.

When the transfer paper P on which the image is formed is stored on the double-sided tray 76, the pair of side fences 7
7, 78, the fences of the transfer paper P are separated from the standby position where the fences are wider than the width of the transfer paper P.
The jogging operation is performed so as to approach each other to a position where both side edges of the transfer paper P are regulated to a predetermined position, thereby aligning the positions of the transfer paper P.

At the time of refeeding the paper, the bottom plate 81 is rotated to raise its leading end, and the leading end of the transfer paper P is pressed against the feed roller 80. Then, by rotating the feed roller 80 in the direction indicated by the arrow A, the re-feeding operation of feeding the transfer paper P in the duplex unit 75 toward the image forming unit 74 is started.

The re-transferred transfer paper P is transferred to an image forming section 74.
The next image is formed on the surface on which the image is not formed, and this is guided to the branch portion 82 whose position has been switched to the linear discharge side, and is discharged from the discharge port 85 to the discharge tray or the like. Is discharged.

[0009]

However, a pair of side fences 77, 7 approaching / separating from each other as described above.
8 is such that if the distance between them is wider than the width of the transfer paper P, the position of both side edges of the transfer paper P cannot be regulated. In some cases, the paper is inclined obliquely to the feeding direction and easily skewed as shown in FIG. FIG.
When the position of the end fence 79 is shifted to the left in the figure with respect to the regular set position, the rear end position of the transfer paper P is located to the left in the figure as much as shown in FIG. As a result, the leading end of the transfer sheet P may not be pressed against the feed roller 80, and non-feeding may occur.

However, the pair of side fences 7
When the fence intervals of 7, 78 are made to approach a position where the width W of the transfer sheet P becomes tight as shown in FIG. 15B, this time, FIGS. ), When the bottom plate 81 is raised, the sliding resistance between the side fences 77 and 78 and the transfer paper P
Is raised only to a position where the leading end of the sheet does not press against the feed roller 80, and the sheet is not fed. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a double-sided unit in which transfer paper does not become non-feed when re-feeding and skew does not occur. .

[0011]

In order to achieve the above object, the present invention provides a double-sided tray for temporarily storing transfer paper having an image formed on one side to form an image again, and a double-sided tray for storing the transfer paper on the double-sided tray. A paper re-feeding unit having a separating member and a paper re-feeding member for separating and re-feeding the transfer paper one by one, and enabling the paper fed in the double-sided tray to be re-fed by the paper re-feeding member. Transfer paper pressing member for pressing and moving to a certain position, a plurality of movable fences for regulating the position of the transfer paper in the double-sided tray to a predetermined position, and approaching / separating the fence from a side edge of the transfer paper. A fence moving means for moving the transfer paper pressing member in a direction in which the fence moves away from the side edge of the transfer paper at least until the transfer paper pressing member starts moving each time the transfer paper pressing member presses and moves the transfer paper. To move to the position Provided with fences movement control means for driving and controlling the fence moving means constituting a duplex unit of an image forming apparatus.

In the double-sided unit, the fence movement control means responds to a decrease in the number of transfer papers after all the transfer papers have been stored in the double-sided tray and a refeeding operation is started by the refeeding means. The fence moving means may also be controlled to move the fence to the standby position.

The timing of moving the fence to the standby position may be a timing when the re-feeding operation of the transfer paper by the re-feeding means is stopped.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a duplex unit of an image forming apparatus according to an embodiment of the present invention;
FIG. 2 is a perspective view showing a mechanism for moving a pair of side fences provided on the double-sided unit, and FIG. 3 is a perspective view showing a mechanism for moving an end fence provided on the double-sided unit.

A duplex unit 1 of the image forming apparatus shown in FIG.
Is a separation tray in which the transfer paper P on which an image is formed on one side is temporarily stored in order to form an image again, and the transfer paper P stored in the double-sided tray 2 is separated one by one and re-fed. A sheet re-feeding unit including a separation roller 42 as a member and the feed roller 13 as a sheet re-feeding member is provided.

Further, there is provided a bottom plate 15 which is a transfer paper pressing member for pressing and moving the transfer paper P stored in the double-sided tray 2 to a position indicated by a virtual line in FIG. . Furthermore, this double-sided unit 1
Is a pair of movable side fences 7 and 8 and an end fence 43 for regulating the position of the transfer paper P in the double-sided tray 2 to a predetermined position suitable for refeeding the paper. A side fence driving device 10 shown in FIG. 2 and an end fence driving device 20 shown in FIG. 3, which are fence moving means for moving in a direction approaching and leaving the side edge, respectively, are also provided.

Further, each time the bottom plate 15 presses and moves the transfer paper P, the pair of side fences 7 and 8 are moved to a standby position, which will be described later, at which the pair of side fences 7 and 8 are separated from the side edge of the transfer paper P at least until the bottom plate 15 starts moving. A control device 60 that drives and controls the side fence driving device 10 and the end fence driving device 20 such that the end fence 43 is moved to a standby position away from the trailing edge of the transfer paper P while moving.
Is provided.

In this embodiment, each time the transfer paper pressing member presses and moves the transfer paper, the control device 60 causes the fence to move at least until the transfer paper pressing member starts moving. It functions as fence movement control means for driving and controlling the fence movement means so as to move to a standby position away from the side edge.

The side fence driving device 10 shown in FIG.
Is a set of racks 51 and 52, and the racks 51 and 52
And a pinion 53 which is disposed between and meshes with them, a gear 54 which meshes with a rack formed along the outer side edge of the rack 52, and a gear 56a via the idle gear 55 on the gear 54. And a side fence drive motor 56 which is a stepping motor that meshes.

The rack 51 is fixed to the lower surface of the side fence 7, and the rack 52 is fixed to the lower surface of the side fence 8. Therefore, when the side fence drive motor 56 is rotated forward, the rotational force is changed to the gear portion 56a,
When the rack 52 is transmitted to the rack 52 via the idle gear 55 and the gear 54, the rack 52
Together with the arrow B.

Then, the rack 52 is provided with a pinion 53
Is meshed with the rack 51 via the
Moves in the direction of arrow C together with the side fence 7. When the side fence drive motor 56 is rotated in the reverse direction,
Similarly, the torque of the gear portion 56a, the idle gear 55,
By being transmitted to the rack 52 via the gear 54,
The rack 52 moves together with the side fence 8 in the direction opposite to the arrow B.

Then, the rack 52 is provided with a pinion 53
Is meshed with the rack 51 via the
Moves together with the side fence 7 in the direction opposite to the arrow C. Therefore, the pair of side fences 7 and 8 can be moved closer to or away from each other according to the number of pulses given to the side fence drive motor 56.

The end fence driving device 20 shown in FIG.
Is composed of pulleys 61, 62, 63, a timing belt 64 stretched between the pulleys, an end fence drive motor 65 in which a gear portion 65a meshes with a gear portion formed on the pulley 61, and the like. Belt 6
4, an end fence 43 is fixed. The end fence drive motor 65 is a stepping motor, and rotates the timing belt 64 by an amount corresponding to the number of pulses given thereto, so that the end fence 43 is rotated by an amount corresponding to the amount of rotation of the timing belt 64. Moves in the direction of arrow E or in the opposite direction.

The pair of side fences 7 and 8 and the end fence 43 are in a standby position corresponding to the transfer paper size selected from the home position before the transfer paper P enters the duplex tray 2 (FIG. 1). Go to As shown in FIG. 4, for example, the side fences 7 and 8 are located at a distance of 10.5 mm from both side edges of the transfer sheet P, and the end fence 43 is 7 mm from the rear edge of the transfer sheet P.
Move to a remote location.

The transfer paper P on which an image is formed on one side
Each time is stored in the double-sided tray 2 shown in FIG. 1, the side fences 7 and 8 and the end fence 43 are moved to the transfer paper regulating position, that is, the position corresponding to the size of the transfer paper P (the side fences 7 and 8 are J is moved to a position where the end fence 43 comes into contact with both side edges of the transfer paper P and the rear end edge of the transfer paper P comes into contact with the transfer paper P, and the transfer paper P is regulated to a predetermined position. Repeat the operation.

Next, a mechanism for rotating the bottom plate 15 will be described with reference to FIG. The mechanism shown in FIG. 5 includes a feed roller 13 and a bottom plate moving unit 11 for rotating the bottom plate 15.
Are driven by a motor 22 which is the same drive source. The bottom plate moving means 11 transmits the rotational force from the motor 22 to the lever holding shaft 39 via the speed reduction mechanism 23, rotates the pressure lever 37 fixed thereto, and moves the bottom plate 15 to the fulcrum 21.
(FIG. 1).

When the motor 22 rotates to rotate the feed roller 13 in the direction of arrow G, the speed reduction mechanism 23
, The bottom plate moving means 11 is actuated, and the bottom plate 15 is raised by the speed reduction mechanism 23 as indicated by the imaginary line in FIG. 1 (the position changes depending on the number of transfer papers stacked on the bottom plate 15).
Go to

The speed reduction mechanism 23 is composed of a number of gears arranged in a train as shown in FIG. 5, and a drive gear 24 fixed to the rotating shaft of the motor 22 has a large size of the first idle gear 25. The large diameter portion of the second idle gear 26 meshes with the small diameter portion of the first idle gear 25.

Further, a third idle gear 27 meshes with a small diameter portion of the second idle gear 26, and an input gear 28 meshes with the third idle gear 27. The input gear 28 is meshed with a gear 31 for sequentially transmitting the rotational force from the motor 22 to another drive system, and the gears 32 and 33 are sequentially meshed with the gear 31.

A cam 29 is mounted on the input gear 28 via a clutch 30 that idles when a predetermined load or more is applied. A pin 34 is attached to the cam 29 at a position eccentric from the center of rotation. One end of a pressure spring 35 is attached to the pin 34.

The other end of the pressure spring 35 is attached to an arm 36 fixed to one end of a lever holding shaft 39 rotatably held at a fixed portion of the duplex unit. The lever holding shaft 39 fixes one end of a pressure lever 37 for rotating the bottom plate 15 at a position substantially corresponding to the transfer center of the transfer sheet.

On the other hand, a roller drive gear 38 meshes with a small diameter portion of the second idle gear 26. The roller drive gear 38 is connected to one end of the feed roller shaft 16 rotatably held by a fixed portion of the duplex unit. Fixed
The feed roller 13 is attached to the feed roller shaft 16.

A mechanism for rotating the bottom plate 15, and FIG.
The drive control of the pair of side fences 7 and 8 and the end fence 43 shown in FIG. The control device 60 includes a central processing unit (CPU) having various judgment and processing functions, a ROM storing each processing program and fixed data, a RAM serving as a data memory for storing processing data, and an input / output circuit (I / O).

The control unit 60 receives various signals output from sensors provided in each unit of the duplex unit 1. And this control device 60
A signal for rotating it is transmitted to a motor 22 for driving the speed reduction mechanism 23, a signal for rotating it to a side fence drive motor 56 for moving the pair of side fences 7 and 8, and an end fence 43. A signal for rotating the end fence drive motor 65 to be moved is output at a predetermined timing.

In the image forming apparatus provided with the duplex unit 1 shown in FIG. 1, when the duplex image forming mode for forming an image on both sides of the transfer paper is selected and the image forming operation is started, an image forming unit (not shown) To form a toner image on one side of the transfer paper P, and transport it to the fixing unit 17 in an unfixed state,
Then, the toner image is fixed.

The transfer paper P is transported by the branch claw 18 switched to the position shown by the phantom line in FIG.
It is conveyed to the double-sided tray 2 by the conveying force of the feed roller 13 and the separation roller 42 through the horizontal conveying path 41 in the double-sided unit 1.

At this time, the cam 29 is at the position shown in FIG. 6, and the bottom plate 15 is at the pivot position lowered as shown.
Immediately after the transfer paper P is fed onto the double-sided tray 2 shown in FIG. 1, the side fences 7 and 8 and the end fence 43 align the positions of the both side edges and the rear edge. Then, in the case of forming a plurality of double-sided images,
This series of operations is repeatedly performed.

When all of the designated number of sheets are stored on the double-sided tray 2 in this manner, the cam 29 rotates to the position shown in FIG. Transfer paper P on tray 2
, And rotates to a rising position indicated by an imaginary line to be brought into contact with the feed roller 13 rotating in the direction opposite to the arrow J of FIG. As a result, the transfer paper P is re-fed sequentially from the topmost paper.

When the bottom plate 15 is rotated to the raised position after all the transfer paper P on which an image is formed on one side is stored in the double-sided tray 2, the side fences 7, 8 are moved to the transfer paper P. When the end fence 43 is set to the restricting position in contact with the rear edge of the transfer paper P, the sliding resistance between the side fences of the transfer paper P and the side fences 7 and 8 is maintained. As a result, the leading end of the transfer sheet P may not be pressed against the feed roller 13 by the pressing force necessary for re-feeding (the transfer sheet P is not sufficiently lifted), and the sheet is likely to be rejected. Was.

However, as described above, this double-sided unit 1 has a pair of side fences 7, 8 at least until the bottom plate 15 starts moving each time the bottom plate 15 presses and moves the transfer sheet P. Is moved to a standby position away from both side edges of the transfer paper P as shown in FIG. 8B, and the end fence 4 is moved as shown in FIG.
The side fence driving device 10 and the end fence driving device 20 are respectively driven and controlled so as to move the transfer sheet 3 to a standby position away from the rear edge of the transfer sheet P.

Accordingly, the transfer paper P does not rub against the side fences 7 and 8 on both sides and the rear edge does not rub against the end fence 43, so that the transfer paper P is prevented from rising from the side fences 7 and 8. And no sliding resistance. Therefore, as shown in FIGS. 9A and 9B, the transfer paper P is raised by the bottom plate 15 until the transfer paper P is smoothly pressed against the feed roller 13 by the pressing force required for re-feeding. Therefore, the paper is not fed.

When the bottom plate 15 is lifted and the transfer paper P is sufficiently pressed by the feed roller 13, FIG.
As shown in (b), the side fences 7, 8 and the end fence 43 are moved to the positions where the side edges and the rear edge of the transfer paper P are regulated. Thereby, it is possible to prevent the transfer paper P from becoming non-feedable and to prevent skew.

In this manner, the plurality of transfer sheets P stored on the double-sided tray 2 are re-fed sequentially from the topmost one, but if the re-feed operation is continued, the transfer sheets P The number of P is reduced, and the stacking height is reduced. Therefore, in this double-sided unit 1, the bottom plate 15 is raised by rotating the motor 22 shown in FIG. 1 by a height corresponding to the reduced number of the transfer sheets P, and the transfer sheet P located at the highest position is again moved. The feed roller 13 is pressed with a pressing force suitable for re-feeding.

At this time, in this double-sided unit 1, FIG.
After the storage device 60 shown in (1) completes the storage of all the transfer papers P in the double-sided tray 2 and starts the refeeding operation by the feed roller 13, the control device 60 responds to the decrease in the number of transfer papers P. The side fence drive motor 56 described with reference to FIG. 2 and the end fence drive described with reference to FIG. 3 move the side fences 7 and 8 from the side edge of the transfer paper to the standby position where the end fence 43 is separated from the rear edge. The motors 65 are driven at predetermined timings.

Thus, when the bottom plate 15 is raised, the side fences 7, 8 and the end fence 43 do not become a resistance. When the side fences 7 and 8 are separated while the transfer paper P is moving (during re-feeding), the side fences 7 and 8 are moved away.
Skew is likely to occur due to the removal of the restrictions on the both side edges of the transfer paper P by 8.

Therefore, in the double-sided unit 1, the timing at which the side fences 7, 8 are separated from the side edge of the transfer sheet P to the standby position as described above is determined by the re-feeding operation of the transfer sheet P by the feed roller 13. The control device 60 controls so that the timing at the time of the stop is reached.

That is, the transfer paper P is intermittently re-fed and sent to the image forming unit for registration with the image on the photoconductor at the registration unit. During the timing between them, the side fences 7 and 8 are separated from each other so as to be spread to the standby position, and the bottom plate 15 is raised so that the transfer paper P is sufficiently pressed by the feed roller 13. Fence 4
3 is moved to a position where the transfer paper P is regulated. As a result, the transfer sheet P can be fed again without causing skew as shown in FIG.

[0048]

As described above, according to the present invention, the following effects can be obtained. According to the duplex unit of the image forming apparatus of the present invention, when the transfer sheet pressing member is pressed and moved to a position where the transfer sheet can be re-fed, the plurality of fences are separated from the side edges of the transfer sheet. The transfer paper that has been re-fed does not rub against the fence and receive resistance, so the transfer paper pressing member presses the transfer paper to a position where the transfer paper can be reliably re-fed. Can be moved. Therefore, it is possible to prevent the transfer paper from being rejected when re-feeding paper, and to prevent skew.

According to the two-sided unit of the image forming apparatus of the present invention, when the number of transfer sheets stored in the double-sided tray is large, the height of the transfer sheets decreases as re-feeding is performed. It is necessary to press and move the transfer paper pressing member toward the re-feeding member by an amount corresponding to the reduced number of transfer papers, and at this time, by moving the fence to the standby position away from the side edge of the transfer paper, In addition, smooth movement of the transfer paper pressing member and the transfer paper can be ensured by eliminating friction between the fence and the edge of the transfer paper. As a result, it is possible to prevent the transfer sheet from being rejected during refeeding,
Skew can be prevented.

According to the double-sided unit of the image forming apparatus of the third aspect, the movement of the fence to the standby position is a timing when the re-feeding operation of the transfer paper by the re-feeding means is stopped. Since the fence does not separate from the side edge of the transfer sheet while the transfer sheet re-fed from the tray is moving, skew can be prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing a duplex unit of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a mechanism for moving a pair of side fences provided in the double-sided unit.

FIG. 3 is a perspective view showing a mechanism for moving an end fence provided in the double-sided unit.

FIG. 4 is a plan view for explaining standby positions of a pair of side fences and end fences provided in the duplex unit of FIG. 1;

FIG. 5 is a perspective view showing a mechanism for operating a feed roller and a bottom plate provided in the double-sided unit.

FIG. 6 is a front view showing a state in which a bottom plate provided in the double-sided unit is in a lowered rotation position together with a cam.

FIG. 7 is a front view showing a state in which the bottom plate is at a raised position together with a cam.

FIG. 8 is a schematic diagram showing a state in which a pair of side fences are separated from each other to be in a standby position and an end fence is also in a standby position, from the front and the side, respectively.

FIG. 9 is a schematic diagram illustrating a state in which the leading end side of the transfer paper is pressed against a feed roller with a pressing force suitable for re-feeding, from the front and the side.

10 is a schematic diagram showing a state where the side fence and the end fence are moved from the position of FIG. 9 to a position for regulating both side edges and a rear edge of the transfer sheet, from the front and the side, respectively.

FIG. 11 is a plan view illustrating a state in which transfer paper is re-fed without causing skew.

FIG. 12 is a schematic configuration diagram showing an example of a conventional color copying machine having a duplex unit.

FIG. 13 is a plan view showing a state in which the transfer paper is skewed during re-feeding.

FIG. 14 is a schematic diagram for explaining a situation in which non-feeding occurs when the position of an end fence is shifted from a regular set position.

FIG. 15 is a schematic diagram showing a state where the end fence is brought into tight contact with the rear end of the transfer sheet and the pair of side fences is brought into contact with both side edges of the transfer sheet from the front and the side, respectively. .

FIG. 16 is a schematic diagram showing a state in which the leading end of the transfer paper is not pressed against the feed roller due to sliding resistance between both side edges of the transfer paper and the side fence, from the front and the side, respectively.

[Explanation of symbols]

 1: Double-sided unit 2: Double-sided tray 7, 8: Side fence 10: Side fence driving device (fence moving means) 13: Feed roller (refeeding member) 15: Bottom plate (transfer paper pressing member) 20: End fence driving Device (fence moving means) 42: separation roller (separation member) 43: end fence 60: control device P: transfer paper

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H028 BA06 BA14 3F343 FA02 FB01 FC01 FC12 GA03 GB01 GC01 GD01 HA12 HB01 HC30 HD18 HE04 HE08 HE12 HE14 HE23 HE26 JA01 JD03 JD09 LA04 LA13 LC03 LC19 LD04 MB03 MB10 MC05 MC08 MC10 MC19 MC21 MC23

Claims (3)

[Claims] 1. A double-sided tray for temporarily storing transfer paper having an image formed on one side to form an image again, and a separation member for separating the transfer paper stored in the double-sided tray one by one and re-feeding the same. Paper re-feeding means comprising: a re-feeding member; a transfer paper pressing member for pressing and transferring the transfer paper stored in the double-sided tray to a position where re-feeding can be performed by the re-feeding member; A plurality of movable fences for regulating the position of the transfer paper in the tray to a predetermined position; a fence moving means for moving the fence in a direction to approach / separate from a side edge of the transfer paper; Each time the pressure member presses and moves the transfer sheet, the drive control of the fence moving means is performed so as to move the fence to a standby position separated from a side edge of the transfer sheet at least until the transfer sheet press member starts moving. Fence movement control hand A double-sided unit for an image forming apparatus, comprising a step. 2. The fence movement control means according to a decrease in the number of transfer papers after all the transfer papers have been stored in the double-sided tray and a refeeding operation is started by the refeeding means. The image forming apparatus according to claim 1, further comprising a control unit that drives the fence moving unit to move the fence to the standby position. 3. The timing according to claim 2, wherein the timing of moving the fence to the standby position is a timing when the re-feeding operation of the transfer sheet by the re-feeding unit is stopped. Image forming device.