JP2849442B2 - Double-sided image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of stacking a transfer sheet having an image formed on one side thereof once in an intermediate tray and re-feeding the transfer sheet to the other side. The present invention relates to a double-sided image forming apparatus capable of forming an image on a surface.

[Conventional technology]

As described above, a double-sided image apparatus capable of forming an image on both sides of a transfer sheet is disclosed in, for example,
There is a copying machine described in JP-A-140363.

In this copying machine, an intermediate tray used for two-sided copying is arranged below the image forming system of the main body, and a gate and a reversing device are provided on the downstream side of the conveyance of the fixing unit. Guides the transfer paper having an image formed on one side in the direction of the intermediate tray, stacks it on the intermediate tray in a state where it is inverted, and then re-feeds it to form an image on the other side I do.

[Problems to be solved by the invention]

However, in an image forming apparatus such as a copying machine in which the intermediate tray is disposed in the apparatus main body, the size of the intermediate tray is determined by the size of the transfer paper on which double-sided image formation is possible. If the A3 large-sized transfer paper can be stacked on the intermediate tray in the state of being fed vertically (the transport direction is the long hand side), the intermediate tray becomes larger and the entire image forming apparatus becomes larger. However, there has been a problem that the demand is going against the miniaturization of the device, which is increasing in recent years.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has an image forming apparatus in which an intermediate tray smaller than the size of a large-sized transfer paper for forming an image on both sides of the transfer paper is provided in the apparatus main body. An object of the present invention is to make it possible to form a double-sided image on a large-sized transfer sheet while reducing the size of the entire apparatus.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, an image is not formed by temporarily stacking a transfer sheet having an image formed on one side in an apparatus main body on an intermediate tray and re-feeding the transfer sheet. In a double-sided image forming apparatus mounted on an upper surface of an apparatus capable of forming an image on a side surface and serving as a gantry or the gantry, a large-sized medium tray in which the length of the intermediate tray in the conveying direction is set in advance is provided. The transfer paper is formed to be shorter than the length of the transfer paper in the conveying direction and is built in the apparatus main body close to the bottom thereof, and the large-size transfer paper stacked on the intermediate tray protrudes from the bottom of the apparatus main body to the outside. An external guide passage is provided to allow a part of the large-size transfer paper protruding from the external guide passage to the outside of the apparatus main body. It is designed to be stacked on a board.

(Operation)

According to the double-sided image forming apparatus configured as described above, when an image is formed on both sides of a preset large-size transfer sheet, when the large-size transfer sheet is fed onto the intermediate tray, the leading end side thereof is moved to the intermediate tray. Since the stacking is performed while protruding from the bottom of the apparatus main body to the outside from the intermediate tray through the external guide passage, even if the size of the intermediate tray is smaller than that of the large-size transfer paper on which double-sided image formation is to be performed, the stacking is performed. You can stack.

Accordingly, the entire image forming apparatus is reduced in size as much as the intermediate tray can be made smaller.

〔Example〕

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

FIG. 1 is a block diagram showing a two-sided copying apparatus which is a two-sided image forming apparatus according to the present invention, and FIG. 2 is an example in which the two-sided copying apparatus is similarly combined with a multi-stage paper feeder and an automatic document feeder to form a copying system. FIG.

In this copying system, as shown in FIG. 2, a double-sided copying apparatus 2 as a double-sided image forming apparatus is mounted on an upper part of a multi-stage sheet feeding apparatus 1 which also functions as a stand, and an automatic document feeder 3 is mounted on the upper side. It is equipped with.

The multi-stage paper feeder 1 includes a first paper feed unit 11 and a second paper feed unit.
12, a third paper supply unit 13, and a fourth paper supply unit 14 are provided in the paper supply device main body 4, and the fourth paper supply unit 14 can supply a large amount of transfer paper. It can also be used as a large-volume feeder (LCT).

Each paper feed unit is provided with a call roller 5 and a paper separation unit 6 composed of a paper feed roller and a separation roller. The transfer paper sent out by the call roller 5 of each paper feed unit is provided. P is conveyed into the duplex copying apparatus 2 by a roller pair 7 provided on the upper part of the paper feeding apparatus main body 4.

Each of the paper feed units 11, 12, 13, and 14 is provided with a paper size detection switch 8 for detecting the size of the transfer paper housed in each paper feed cassette.

The automatic document feeder (ADF) 3 includes a document tray 16, a document feeder 15 having a pickup roller, a separation roller, a blocking roller, and the like, and an endless transport belt that is stretched between a plurality of rollers and rotates. 18, a pair of pull-out rollers 19, a transport unit 17 having various transport rollers and the like, a reversing roller 23 and a deflecting claw 22.
And a paper discharge unit 21 provided with various paper discharge rollers such as a reverse paper discharge roller 24.

To obtain a copy from a one-sided original using the automatic original feeder 3, first, the originals D are set on the original tray 16 in page order from the top with the original surface facing upward.

Then, the document D is conveyed by being separated into one sheet in order from the upper page by the document feeder 15 and the upper part of the duplex copying apparatus 2 by the endless conveyance belt 18 rotating counterclockwise. Is transported to a predetermined position on the contact glass 9.

Then, when the exposure by the optical system 30 described later in the duplex copying apparatus 2 is completed, the endless transport belt 18 rotates counterclockwise again, and the document D on the contact glass 9 moves rightward in FIG. The sheet is conveyed, inverted by a pull-out roller 19, and conveyed to the left in a conveying path in the conveying section 17, and is inverted by an inverted sheet discharging roller 24, and the image surface is lowered by a sheet discharging section 21. In this state, the original is discharged onto an original receiver 25 provided below the original tray 16.

When a copy is obtained from a two-sided original, the original D is placed on the original tray such that one page is at the top in page order from the upper side.
16 and is conveyed onto the contact glass 9 in order from the first page by the same operation as in the case of copying a single-sided original.

When the copying of the first side is completed by the same operation as described above, the endless transport belt 18 is rotated clockwise in FIG.
To the reversing unit 20.

The document D is inverted by the reversing roller 23 and the deflection claw 22 rotated to the position shown by the solid line in FIG. 2, and is again conveyed onto the contact glass 9 and set.

When the copy on the second side (back side) is completed, the original D is sent to the reversing unit 20 in the same manner as when the copy on the first side is completed, and the deflecting pawl 22 is switched to the position shown by the broken line in FIG. The document is discharged from the paper output unit 21 onto the document receiver 25 through
The originals subsequent to the first sheet are sequentially stacked with the first surface (front surface) facing downward.

As shown in FIG. 1, the double-sided copying apparatus 2 stacks transfer paper P on which an image is formed on one side in the apparatus main body 27 once on an intermediate tray 28, and re-feeds the transfer paper P. An image can be formed on the surface on which no image is formed, and the length of the intermediate tray 28 in the transport direction (first
(Length in the left-right direction in the figure) is set shorter than the length in the transport direction of a large-size transfer paper of, for example, A3, and is built in the apparatus main body 27, and the large-size transfer paper P is An external guide passage 29 is formed so as to protrude from the intermediate tray 28 to the outside of the apparatus main body 27, and a part thereof is stacked on a top plate 63 of the multi-stage paper feeder 1, and a pressure driving roller is provided near the entrance of the passage. 57 are provided.

In this embodiment, the external guide passage 29, the pressure driving roller 57, and the top plate 63 of the multi-stage paper feeder 1 stack large transfer paper out of the intermediate tray to the outside of the apparatus main body. Means.

A photoreceptor drum 31 rotatable in the direction indicated by an arrow shown in FIG. 1 is provided at a substantially central portion in the apparatus main body 27, and a charging charger 32 and first and second developing devices are provided therearound. 33, 34, transfer charger 35, separation charger 36, cleaning device
There are 37 mag each.

The optical system 30 is for imagewise exposing the photosensitive drum 31. The optical system 30 is disposed below the contact glass 9 so as to be able to scan an original image, and is constituted by a light source, a plurality of movable mirrors, lenses, and the like. ing.

On the other hand, on the right side of FIG. 1 of the apparatus main body 27, there is provided a feeder provided with separate feed rollers for separating and feeding the transfer paper P in the paper feed cassettes 38 and 39 into one sheet. Paper units 40 and 41 are provided, respectively, and the transfer paper P fed from the paper units is a pair of registration rollers 42, a suction conveyance roller 43, a fixing device 44,
The sheet is discharged onto a sheet discharge tray 47 through a fixing discharge roller pair 45 and a main body discharge roller 46.

In addition, a registration roller front sensor 48 is provided in front of the registration roller pair 42.

A manual paper feed unit 50 is provided above the paper feed unit 40, so that paper can be fed from either manual paper feed or cassette paper feed.

Further, a first gate claw 51 and a second gate claw 52 are provided between the fixing discharge roller pair 45 and the main body discharge roller 46, respectively, to transfer the transfer paper P passing through the fixing discharge roller pair 45 to both sides. To the path 53, or through the guide surface 26a of the guide member 26 through the second gate pawl 52, and to the stack surface 2 of the intermediate tray 28.
8a.

At the end of the double-sided conveyance path 53, a double-sided pull-out roller pair 58 is provided, and a sensor 61 is provided in front of the pair, and a sensor 56 is provided on the right side of the second gate claw 52 in FIG.

Also, the intermediate tray 28 is indicated by broken lines in FIG. 1 which guides the yoga 64 and the leading end side of the transfer paper P sent from the second gate claw 52 side onto the intermediate tray 28 to the back surface discharge turn section 55. A pressurizing drive roller 57 and a pick-up roller which are provided with a rotatable paper guide gate claw 54 at a position above the stack surface 28a of the tray provided with the 59 are provided at intervals in the transport direction.

Further, to the right of FIG.
Re-feed roller 65 and separation roller that are pressed against each other in the vertical direction
66, and a pair of transport rollers 67 are provided on the downstream side of the transport.

Hereinafter, using this two-sided copying apparatus 2, a one-sided copy for transferring an image to one side of a transfer sheet, a two-sided copy for transferring an image to both sides, and a combined copy for transferring an image to one side of a transfer sheet a plurality of times, respectively. Each of the copying steps in the case where the copying is performed will be described.

Single-sided copy process The transfer paper P fed from the manual paper feed unit 50 or the paper feed units 40 and 41 shown in the first time is conveyed by the registration roller pair 42 in synchronization with the toner image on the photosensitive drum 31. Then, the toner image is transferred to the upper surface in FIG. 1 by the transfer charger 35, and is separated from the photosensitive drum 31 by the separation charger 36.

The transfer paper P is sent from the suction conveyance roller 43 to the fixing device 44, where the toner image is fixed, and reaches the fixing paper discharge roller pair 45.

When the number of originals is one, it is not necessary to discharge the transfer paper by turning over the paper and then discharging the reverse side. The first gate claw 51 and the second gate are located at positions shown by solid lines in FIG.
The paper passes through 52 and is discharged onto a paper discharge tray 47 by a paper discharge roller 46 of the main body.

Further, when a plurality of documents are to be transferred and the image of the document is to be transferred to a plurality of transfer papers P, it is necessary to discharge the transfer papers P in reverse order in order to discharge them in a page order. After exiting the fixing discharge roller pair 45, the transfer paper P is conveyed onto the intermediate tray 28 with the first gate claw 51 at the position shown by the solid line in FIG. 1 and the second gate 52 at the position shown by the broken line. .

In this embodiment, in the case of a transfer sheet of a large size (B4 size or more) larger than the A4 vertical size, the paper guide gate pawl 54 is set to the position shown by the broken line in FIG. The leading end side of the paper P is made to enter the back discharge turn section 55, and the pressure driving roller 57 at the lower position shown by the imaginary line in FIG. 1 is rotated counterclockwise until the rear end of the transfer paper P passes the sensor 56. The transfer roller P is conveyed in the direction of rotation and the rotation of the pressure driving roller 57 is stopped at the moment when it passes therethrough, and then it is rotated clockwise to discharge the transfer paper P by the main body discharge roller 46. Stacking is performed on the tray 47 with the image surface facing down.

At this time, the pressure driving roller 57 is moved to the leading end of the transfer paper P (first
When (the left side in the figure) reaches the main body discharge roller 46, the pressurizing drive is stopped and the next transfer paper is awaited.

As described above, in this copying system, the document D is fed in the page order by the automatic document feeder 3 described with reference to FIG. 2, so that when copying only one side, the transfer sheet P is placed with the image side down. The pages are arranged in the page order by discharging the sheets.

Double-sided copying process The transfer paper P is subjected to a copying process similar to the one-sided copying process described above.
When the sheet passes through the fixing discharge roller pair 45, the transfer paper P is sent to the double-sided conveyance path 53 and passes through the double-sided pull-out roller pair 58 because the first gate claw 51 is at the position shown by the broken line in FIG. The sheet is fed onto the intermediate tray 28 while being inverted.

At this time, the attracting roller 59 is at the ascending position indicated by the solid line in FIG. 1, and when the rear end of the transfer paper P passes through the sensor 61, the pressing drive roller 57 at the descending position rotates clockwise,
It stops when a predetermined rotation time elapses according to the size of the transfer paper.

The method of stacking the transfer paper P on the intermediate tray 28 depends on the size of the transfer paper, and up to the A4 size vertical feed (length in the transport direction is 297 mm) as shown by a virtual line in FIG. The transfer sheet is stacked on the stack surface 28a of the intermediate tray 28. However, if the transfer sheet is a larger size, for example, B4 or A3 size transfer paper, the length in the transport direction is longer.
Left side (tip side when stacking) as shown by the solid line in the figure
However, while sliding on the stack surface 28a, the transfer paper itself enters into the external guide passage 29 communicating with the outside of the apparatus main body 27 by its own weight.

That is, A3 size vertical feed (420 mm length in the transport direction)
When stacking a long transfer sheet P as shown in FIG. 1, the leading end of the transfer sheet P is protruded from the external guide passage 29 formed at the bottom of the apparatus main body 27 to the outside of the apparatus main body, and the multi-stage paper feeder is provided below the apparatus main body 27. Stack on the top plate 63 of the apparatus 1.

At this time, the pressure driving roller 57 rotates clockwise in FIG. 3 and descends as indicated by the imaginary line, thereby assisting the transfer of the large-sized transfer paper P to the left.

Since the upper surface of the top plate 63 is in a horizontal plane state in a normal case, it is suitable for stacking the transfer paper P.
Further, since the position of the hand of the operator hardly touches the transfer sheet P, the transfer is not easily hindered, which is convenient.

When stacking such large-size transfer paper on the intermediate tray, a part of the transfer paper P is stacked outside the apparatus main body 27 of the copying apparatus. It is also more convenient to confirm.

The guide member 26 on the left side of the intermediate tray 28 in FIG.
Since the guide surface 26a is higher than the stack surface 28a of the intermediate tray 28, the leading end of the transfer paper P that moves while sliding on the stack surface 28a to the left from the right in FIG. It comes into the outside guide passage 29.

In this way, the transfer paper P stacked on the intermediate tray 28, even if it is one or a plurality of sheets, is aligned with the side edges regulated by the joggers 64 shown in FIG. The paper is fed between the paper re-feed roller 65 and the separation roller 66 by a take-up roller 59 rotating clockwise, and if there are a plurality of sheets, they are separated into one and the conveyance rollers shown in FIG. The sheet is fed again to the pair of registration rollers 42 via the pair 67.

Then, the transfer paper P is temporarily stopped, and then the photosensitive drum is stopped.
The image is conveyed again at the same timing as the image for the second side on the first side 31, and the image is transferred to the second side by the same operation as the above-described one-sided copy, and passes through the fixing device 44 to the fixing discharge roller pair 45. Proceed until:

At this time, since the first gate claw 51 and the second gate claw 52 are both at positions shown by solid lines in FIG. 1, the transfer paper P is stacked on the paper discharge tray 47 by the main body paper discharge roller 46 as it is. Is done. Thus, the stack is completed with the first surface facing downward and the second surface facing upward.

As described above, in this embodiment, when a plurality of sheets of transfer paper are copied on both sides, the transfer paper after the image has been transferred to the second side is discharged without turning over the first side without turning over the first side. Since the distance between the transfer papers can be shortened, copy productivity twice or more than that of a normal copying paper is obtained.

Synthetic copying process An image is formed on one side (first side) and the fixing and discharging rollers 45
The transfer paper P that has exited the first position is located at the position indicated by the solid line in FIG.
The guide surface 26 shown in FIG. 3 of the guide member 26 being guided by the gate claw 51 and the second gate claw 52 at the position indicated by the broken line.
The sheet is fed onto the stack surface 28a of the intermediate tray 28 through a.

Even if the transfer paper P is one or more,
The positions of both side edges are regulated by 64, and the paper is fed between the paper feed roller 65 and the separation roller 66 by the take-in roller 59, and when there are a plurality of sheets, they are separated one by one and are shown in FIG. The sheet is fed again to the pair of registration rollers 42 via the pair of conveying rollers 67 shown.

The image is then fed again at a predetermined timing with the image to be combined on the photosensitive drum 31 and reaches the fixing discharge roller pair 45 by the same operation as in the case of single-sided copying.

Thereafter, in the case of a single composite copy, both the first gate claw 51 and the second gate claw 52 are at the positions indicated by the solid lines, and the transfer paper P is directly transferred to the discharge tray by the main discharge roller 46. Stacked.

When a composite copy is to be made on a plurality of transfer papers, it is necessary to arrange the pages in the same order as in the case of single-sided copy.

That is, the transfer sheet P after exiting the fixing discharge roller pair 45 after re-feeding and completing the composite copy is moved to the first gate claw 51 shown by the solid line in FIG. 1 and the position shown by the broken line in FIG. The transfer paper P is conveyed onto the intermediate tray 28 by a certain second gate claw 52, and is conveyed by rotating the pressure driving roller 57 in the counterclockwise direction until the rear end of the transfer paper P passes the sensor 56. At the moment of passing, stop the rotation of the pressure drive roller 57,
This time, it is rotated clockwise, and is stacked on the paper output tray 47 by the main body paper output roller 46 with the image surface facing down.

In this embodiment, when only one composite copy is to be obtained (1to1 composition), the maximum size of the A3 size can be set.
A4 size vertical feed or less.

However, when the discharge position from the second gate claw 52 is set on the left side of FIG. 1 (the apparatus becomes large), a plurality of sheets can be combined even for a large-size transfer paper such as A3. Will be possible.

FIG. 4 is a block diagram showing a control system for controlling a copying system composed of a multi-stage paper feeder 1, a duplex copying machine 2, and an automatic document feeder 3 according to the present embodiment, and a related configuration thereof.

This copying system includes a sequence controller 70, an operation controller 71, an AC controller 72, a motor controller 73, and an ARDF controller 74.

The sequence controller 70 performs timing control of input and output operations of various sensors and loads relating to image formation and transfer of transfer paper, and mode control based on input data obtained by pressing a key switch obtained from the operation controller 71. And serial communication between them to control the entire copying system.

The operation controller 71 transmits key input data from the key switch to the sequence controller 70, and performs control for performing various displays based on the mode data received from the sequence controller 70.

The AC controller 72 controls the surface temperature of the fixing heat roller of the fixing device 44 (FIG. 1) and the exposure lamp voltage of the optical system 30 (FIG. 1) by PI control.

The motor controller 73 controls the speed of the scanner motor of the optical system 30 and the position of the lens and mirror motor for moving the lens and the mirror, and the ARDF controller 74
In accordance with a command from the sequence controller 70, each control of document feeding, stopping, and discharging is performed.

Each of these controllers has a central processing unit (CP
U), peripheral LSIs, drivers, etc., each of which receives signals from various sensors, performs control for driving various loads such as motors and solenoids, and performs synchronous control by serial communication between controllers. Is going.

〔The invention's effect〕

As described above, according to the present invention, when stacking large-size transfer paper on the intermediate tray, a part of the transfer paper protrudes outside the apparatus main body and is stacked.
Even if the entire image forming apparatus is made smaller by making the length of the intermediate tray in the transport direction shorter than a preset length of the large-size transfer paper in the transport direction, the large-size transfer paper can be stacked on the intermediate tray and placed on both sides. Image formation can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a two-sided copying apparatus which is a two-sided image forming apparatus according to the present invention, and FIG. 2 shows a copying system similarly constituted by the two-sided copying apparatus, a multi-stage paper feeder and an automatic document feeder. FIG. 3 is a cross-sectional view showing the vicinity of an external guide passage used when a large-size transfer sheet protrudes from the intermediate tray to the outside of the apparatus main body and is stacked, and FIG. 4 is a view of FIG. FIG. 2 is a block diagram showing a control system for controlling the copying system and its related configuration. DESCRIPTION OF SYMBOLS 1 ... Multi-stage paper feeder, 2 ... Duplex copying machine 3 ... Automatic document feeder, 27 ... Main body 28 ... Intermediate tray, 29 ... External guide passage 51 ... First gate claw, 52 ... … Second gate claw 53… Dual-sided conveyance path, 57… Pressure drive roller 63… Top plate, P… Transfer paper

Claims (1)

(57) [Claims] A transfer sheet having an image formed on one side in an apparatus main body is stacked once on an intermediate tray, and the transfer sheet is re-fed so that an image is formed on a surface on which an image is not formed. In a double-sided image forming apparatus which can be formed and is mounted on a frame or a device serving as the frame, the length of the intermediate tray in the direction of conveyance is set in advance in the direction of conveyance of large-size transfer paper. An external guide formed to be shorter than the length and built in near the bottom of the apparatus main body and allowing the large-sized transfer paper stacked on the intermediate tray to protrude from the bottom of the apparatus main body to the outside. A passage is provided, and a part of the large-sized transfer paper protruding from the external guide passage to the outside of the apparatus main body is stacked on the gantry or on the top plate of the apparatus serving as the gantry. A double-sided image forming apparatus characterized in that: