JP2000010371A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute a number of pieces of duplex copy or duplex print at high speed by providing a regulating means for correcting the oblique or horizontal slippage of a transfer material before it is guided to a first image forming part and a second image forming part. SOLUTION: A first carrying passage 11 is provided in such a manner that it is substantially horizontal in the position from the paper feeding position of a transfer material carried from a paper feed port 18 communicating with a paper feed part 2 to the transfer position 20 of a first image forming part 12, and the distance between the both is longer than the length of a maximum size transfer material. A second carrying passage 14 guides the transfer material fixed to a fixing device 37a to the transfer position 20b of a second image forming part 15. The second carrying passage 14 has a looped carrying passage 41 for carrying the transfer material so that the first surface is down, and a second regulating means 13 provided so as to be substantially horizontal from the position where the second surface of the transfer material is turned up to the transfer position 20b of the second image forming part 15, which regulates the horizontal slippage of the transfer material caused between them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to an image forming apparatus such as a printer, and more particularly to an image forming apparatus capable of forming an image on both sides of a transfer material.

[0002]

2. Description of the Related Art As a model of an image forming apparatus such as a copying machine or a printer, there has been proposed an apparatus capable of forming an image on both the front and back surfaces of one transfer material. Such an apparatus, which is generally known, forms a first image on one surface of a transfer material, and temporarily stores the transfer material in a tray for reversing the front and back called an intermediate tray provided in the image forming apparatus. Then, the transfer material is re-fed from the intermediate tray at an appropriate timing, and is sent along the same route to the same image forming unit as that on which the first image was formed, where the second image is transferred onto a different surface of the transfer material. Is formed and then discharged outside the image forming apparatus.

Such an apparatus may be used in a relatively slow manner in which two developments are reproduced one by one on the front and back surfaces of one transfer material, but a large number of originals may be used. Is not suitable for continuous reproduction on both sides, or when a large number of different originals are reproduced as double-sided copies or prints at high speed, and there are some problems to be solved. .

Further, as disclosed in Japanese Patent Application Laid-Open No. 9-43912, two image forming means are vertically arranged, and each image forming means is opposed to the front surface and the back surface of the transfer material, and both sides are formed in one pass. 2. Description of the Related Art An image forming apparatus configured to form a copy is known. Each of the image forming units has a fixing device at the subsequent stage, and the toner image is fixed after forming. The transfer path of the transfer material from the first image forming unit to the second image forming unit is substantially U
It is shaped like a letter. Compared to the image forming apparatus having the above-described intermediate tray, it is suitable for a case where a large number of originals are continuously reproduced on both sides, or a case where a large number of originals are reproduced as a double-sided copy or print at a high speed. In addition, there are still problems that cannot be solved when the process speed is further increased or maintenance is improved.

For example, if the process speed is 300 mm / sec
In the case of the above-described high speed, image formation is caused by a lateral shift due to a pick-up for transporting the transfer material to the image forming unit one by one and a skew of the transfer material caused by a slip of a transport belt or a transport roller in a transport path of the transfer material. The timing of the transfer material to be inserted into the transfer position of the copy unit is shifted, or the transfer material is inserted into the image forming unit while being skewed, so that a toner image can be formed at a desired place of the transfer material. Disappears. In addition, there is a problem in that high-speed image formation of a large amount of transfer material causes rapid consumption of components and frequent replacement of components.

[0006] Further, in the case of forming a two-sided color image or a two-color image, the above-described image forming apparatus has not been used yet.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and enables high-speed double-sided copying and double-sided printing on a large number of sheets. It is an object of the present invention to provide an image forming apparatus capable of performing satisfactory image formation without any problem, and to provide an image forming apparatus capable of improving operability such as maintenance and inspection with a simple configuration.

[0008]

In order to solve the above-mentioned problems, an image forming apparatus according to the present invention comprises a first image forming section for forming a first toner image with a first surface of a transfer material facing upward. A conveyance path formed in a loop for conveying the first surface downward so that the first surface faces downward, and a second toner having a second surface of the transfer material facing upward. A transfer material conveyed from a paper supply unit in an image forming apparatus having a second image forming unit for forming an image, wherein the first image forming unit and the second image forming unit each have a fixing device. And a first regulating unit that regulates the lateral displacement of the transfer material by providing a substantially horizontal distance between the sheet feeding position and the transfer position of the first image forming unit so as to be longer than the maximum size of the transfer material. The first transport path and the loop-shaped transport path are used to transfer the transfer material. Is provided in a substantially horizontal direction from the position where the surface is downward to the transfer position of the second image forming unit, and is provided so as to be longer than the transfer material of the maximum size. And a second transport path provided with a second regulating means for regulating.

[0009] Further, the first and second regulating means both regulate on the basis of one side edge of the transfer material, and the image forming apparatus further comprises a second image forming section. Downstream of the second fixing device, a third conveyance path for discharging the transfer material to the outside of the device so that the first surface of the transfer material faces downward.

Further, the first restricting means and the second restricting means are unitized, and a drive transmitting means for driving these units is detachably provided on either end of a drive shaft of the unit. The drive transmission means is provided on at least one of the two ends so that the drive transmission means can be connected to a drive source provided on the same side of the apparatus main body, so that the first restriction means and the second restriction means are interchangeable. The first image forming unit and the second image forming unit are unitized, and a drive transmission unit for driving these units can be detachably attached to either end of a drive shaft of the unit. The first image forming unit and the second image forming unit are provided with the drive transmission means on at least one of both ends thereof so as to be connectable to a drive source provided on the same side of the apparatus main body. Compatible It is characterized in.

With such a configuration, the transfer material picked up by the paper supply unit is transferred by the first conveyance path provided with the substantially horizontal first regulating means until it reaches the first image forming unit. The sheet is aligned on one side of the sheet and guided in a straight state toward the first image forming unit. The transfer material on which the first toner image has been formed on the first surface by the first image forming unit is fixed. Next, the transfer material is conveyed through the loop-shaped conveyance path so that the second surface of the transfer material faces upward, and is aligned by the first restriction means by the second conveyance path including the second restriction means. The transfer material is guided toward the second image forming unit in a straight state with one side of the transfer material in the same direction as the reference being aligned. The transfer material on which the second toner image has been formed on the second surface by the second image forming unit is fixed. Next, the transfer material is conveyed through the third conveyance path toward a discharge port to an accumulation unit provided at a position opposite to a position where the transfer material is fed.

Further, the first image forming unit and the second image forming unit, and the first regulating unit and the second regulating unit are unitized, and the respective units can be easily replaced. Further, a drive transmission means for driving these units is detachably provided on any of both ends in the axial direction of the unit, and a drive transmission means is provided on at least one end thereof and provided on the same side of the apparatus main body. Because it can be connected to the drive source, the insertion into the apparatus main body can be performed on only one side using any unit.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the image forming apparatus 1 of the present invention. The image forming apparatus 1 includes a paper feed unit 2 that feeds transfer materials that have been roughly grouped one by one, an image forming unit 3 that forms images on the front and back surfaces of the transfer material, and a transfer material on which images are formed on at least both sides. Stacking unit 4 for orderly stacking
And each unit is unitized and separable. Each unit has, for example, a size that can be carried into a normal-sized elevator.

The paper supply unit 2 includes paper supply tables 5a, 5b, and 5c on which transfer materials having different sizes are placed, and paper supply tables 5a, 5b, and 5c.
Paper feed rollers 6a, 6b, 6c for picking up the uppermost sheet of the transfer material selected from 5b, 5c, and lifts 7a, 7b, 7 as an elevator mechanism such that the height of the upper surface of the transfer material is always constant. 7c. Each paper feed table 5
From a, 5b, and 5c, a transporting unit 9 that transports a selected transfer material by a transporting roller or a transporting belt toward a common outlet provided in the paper feeding unit 2 is provided. In the illustrated example, the paper feed rollers 6a, 6b, and 6c each have a perforated paper feed belt provided with a suction unit, and the leading end of the paper feed belt contacts the uppermost surface of the loaded transfer material and is suctioned by the suction unit. Then, the uppermost one of the transfer materials is separated from the second and subsequent transfer materials and picked up, and the transfer means 9 is moved by moving the belt.
It is guided to. The picked up transfer material is the paper feed unit 2
Is conveyed through the conveying means 9 toward the outlet 8 communicating with the image forming section 3. The elevator mechanism moves the stacking tables 5a, 5b, and 5c on which the transfer materials are stacked upward by the lifts 7a, 7b, and 7c in an elevator manner in accordance with the amount (height) of the transfer material consumed by image formation. The top end of the material is kept at a certain height that allows the pickup.

Transfer materials can be accumulated in units of thousands of sheets. For example, the doors provided on the side of the apparatus main body are opened and the accumulation tables 5a, 5b, 5c are set outside the sheet feeding section 2 via a rail mechanism or the like. It is provided so that drawers and new transfer materials can be easily accumulated. For the selection of the transfer material, the transfer path of the first transfer means 9 is appropriately selected through the operation panel in accordance with the instruction of the operator, and the transfer material of a desired size is fed to the image forming unit 3. The transfer material may be of a type that cuts and uses roll paper in addition to every sheet,
A plurality of paper cassettes or paper decks may be provided therein, and transfer materials of different sizes may be stacked in the cassettes or on the upper surface of the deck.

The image forming section 3 forms a toner image on a first surface of a transfer material, including a first conveyance path 11 provided with a first restricting means 10 for restricting a lateral shift of the transfer material during pickup. A first image forming unit 12 for fixing, a second conveying path 14 formed in a loop including a second regulating unit 13 for preventing skew of the transfer material during conveyance, and a second surface of the transfer material A second image forming unit 15 that forms and fixes an image on the image forming unit, and a third conveying path that conveys the transfer material toward an outlet 16 that is provided in the image forming unit 3 and communicates with a stacking unit 4 described below. Having.

The first conveying path 11 is substantially horizontal between a sheet feeding position of the transfer material conveyed from a sheet feeding port 18 communicating with the sheet feeding section 2 and a transfer position 20a of the first image forming section 12. And a longer distance than the maximum size transfer material. The paper feed position is a position where the rear end of the transfer material is apart from a paper feed roller or the like provided at the paper feed port, and the transfer position is
This is a position where the first surface of the transfer material passes between the image carrier and the transfer roller. By transferring the transfer material in a substantially horizontal state, the deflection and lateral displacement of the transfer material are minimized, the transfer of the transfer material is stabilized, and the timing of image formation performed by the first image forming unit 12 is improved. It is assumed. First
Of the transfer material from the position where the rear end of the transfer material is separated from the sheet feeding roller pair 19, the first image forming unit 12
Is provided until the transfer position 20 is reached. Preferably, the rear end of the transfer material is provided between a position distant from the sheet feeding roller pair 19 and a detection sensor 21a that detects the front end of the transfer material.

The detection sensor 21a is composed of a photo sensor or the like, and a distance from a detection position of the detection sensor 21a to a transfer position 20a of the first image forming unit 12 and an image projection device provided in the first image forming unit 12. The distance from the lighting position of the LED array 22a to the transfer position 20a is provided to be substantially the same. The detection sensor 21a detects the leading end of the transfer material, and the LED as the image projection device 22a according to the detection signal. By starting to turn on the array, printing can be performed at a desired position with good timing without stopping the transfer material.

As shown in FIGS. 2 and 3, the first regulating means 10 has, for example, a conveying roller 23 or a conveying belt 24 provided obliquely with respect to the image carrier 25, so that the transfer material at the time of pick-up is removed. The transfer material that is laterally displaced at the time of pulling out or during conveyance is conveyed obliquely to the image carrier 25a of the first image forming unit 12. These transport rollers 23 or, in order to drive the transport belt 24, are provided with a drive transmission unit and a drive source as described later. In the illustrated example, a gear 80 as drive transmission means is attached to one end of a support shaft that supports the transport roller 23 or the transport belt 24, and the gear 80 is connected to a drive source 90 of the apparatus main body. The transport roller 23 or the transport belt 2
For example, a plurality of balls 26 or rollers 27 that slightly press the transfer material conveyed onto the transfer material 4 are rotatably provided, and further abut on one side surface of the transfer material to restrict further oblique conveyance of the transfer material. A plate-like guide member 28 is provided. The guide member 28 is provided on the moving direction side of the transfer material conveyed obliquely and in a direction orthogonal to the axial direction of the image carrier 25. The transfer material having a lateral shift caused by the first regulating means 13 having such a configuration is transferred to the transfer belt 2.
The transfer material is conveyed obliquely by the transfer roller 4 or the conveyance roller 23, one side of the transfer material abuts the guide member 28, and the transfer position of the transfer material is regulated so as to be in a direction orthogonal to the axial direction of the image carrier 25. The sheet is conveyed toward the image forming section 12. The transfer material that abuts against the guide member 28 slides due to the ball 26 or the roller 27 that weakly contacts the transfer material, so that the transfer material can be transported in a straight state without further transporting the transfer material obliquely.

The first image forming section 12 is for forming a first toner image with the first surface of the transfer material facing upward, and has a configuration utilizing electrophotography. It has an image carrier 25a such as a photosensitive belt. One or a plurality of charging devices 29a such as a corona charger or a charging roller for uniformly charging the surface of the image carrier 25a around the image carrier 25a, and the first original data read by a scanner or the like are displayed by an LED. An image projection device 22a for projecting the latent image on the image carrier 25a to form a latent image on the image carrier 25a, a developing device 30a for supplying a charged toner to the latent image to form a first toner image, A transfer device 31a for transferring the first toner image on the image carrier 25a onto the first surface of the transfer material sent from the transfer member 2;
A cleaning device 32a for removing the toner remaining on the surface of the image carrier 5a and an eraser lamp 33a for uniformly removing the surface potential of the surface of the image carrier 25a are provided so that they sequentially act on the image carrier 25a. And image formation is performed as is well known. An image is formed by a known image forming method. When a polymerized toner is used as the developer, the cleaning device 32a may be omitted.

The transfer device 31a has a plurality of transfer rollers 34 having different widths, and is provided so as to be rotatable about a fulcrum 35. One of the transfer rollers 34 corresponding to the width of the transfer material to be used is provided. One of them is selected and positioned at a position where it comes into contact with the image carrier 25a or comes into contact with the image carrier 25a via a transfer material. Further, the transfer roller 34 having a width slightly shorter than the width of the transfer material is selected according to the size of the transfer material to be used. In the illustrated example, for example, A4,
Although transfer rollers having different widths corresponding to five types of sizes such as A3, B5, B4, and B3 are provided, the number is not limited.

Reference numeral 36a denotes a fixing device 37 for transferring a transfer material carrying an unfixed first toner image formed on the first surface.
4A shows a transport belt that transports toward a. For example, a single wide endless belt extending over the entire width of the largest transfer material in the width direction or a transport belt 36a composed of a plurality of endless belts appropriately divided in the width direction of the transfer material and arranged in parallel And a suction means 38a which acts to transport the transfer material in close contact with the transport belt 36a and transports the same. A plurality of intake ports are provided at predetermined positions on the peripheral surface of the conveyor belt 36a, and an intake box having a number of intake holes on the upper surface arranged in a space surrounded by the conveyor belt 36a is suctioned by suction means 38a such as a blower.
The transfer material is conveyed to the transfer belt 36a in close contact with the peripheral surface of the transfer belt 36a by suctioning air from the intake ports toward the inside of the transfer belt 36a.

The role of the transport belt 36a is important. As described above, the transfer material having the unfixed toner image on the upper surface must be transported to the next portion without disturbing or destroying the toner image. Must. Since transfer materials to be used have different sizes, for example, when a small-size transfer material is used, the suction port (hole) of the belt portion (and the suction box) not covered with the transfer material is used. Unnecessary useless suction is performed from the above, and efficient suction of the transfer material cannot be sufficiently expected. Therefore, depending on the size (width) of the transfer material to be suctioned, the suction width of the suction box is appropriately changed from the (both) ends to the center of the suction box between the upper surface of the suction box and the conveyor belt 22a. A movable (a pair of) shielding plates may be provided to change the position in the width direction. In such a case, the shielding plate is set when the size of the transfer material is set in advance, or
When the size is detected in the transport path sent to the first image forming unit 3, the image is automatically moved to an optimum position according to the size of the transfer material.

The transfer material on which the first toner image is formed is
Next, the sheet is sent to the fixing device 37a. In the illustrated example, the first fixing device 37a is a so-called heat fixing roller device comprising a heating roller 39a and a pressure roller 40a which are in pressure contact with each other, and the first toner image is transferred by the transfer material passing between these rollers. The material is heated and fixed.

The temperature of the first fixing device 5 is set to a low fixing temperature at which the first toner image does not scatter at least. The fixing temperature is controlled by the second image forming unit 1.
5 and the second transport path 14, the peripheral devices are not contaminated and the first toner image is not disturbed. The first toner image is transferred to a second fixing device 37b set to a normal fixing temperature described later.
Is fixed between the heating roller 24b and the pressure roller 25b. In addition to the suction of the transfer material, the transport belt 36a has a function of sucking heat generated from the fixing device 37a and discharging the heat to the outside of the device.

The second conveying path 14 transfers the transfer material fixed on the fixing device 37a to the transfer position 20b of the second image forming unit 15.
First, a loop-shaped transport path 41 that transports the first surface downward, and a second image forming unit from a position where the second surface of the transfer material faces upward. There is provided a second regulating means 13 which is provided in a substantially horizontal direction between the 15 transfer positions 20b and is provided so as to be longer than the transfer material of the maximum size, and restricts a lateral displacement of the transfer material that may occur therebetween. .

The second regulating means 13 has the same structure as that of the first image forming section 12 described above, that is, the second regulating means 13 passes through the loop-shaped conveyance paths 41a and 41b, and the second surface of the transfer material faces upward. It is provided so as to be substantially horizontal between the position and the transfer position 20b of the second image forming unit 15 and longer than the transfer material of the maximum size. By transporting the transfer material in a substantially horizontal state, the deflection and lateral displacement of the transfer material are minimized, the transfer of the transfer material is stabilized, and the timing for forming an image with the second image forming unit 15 is good. It is assumed that. The second regulating means 13 is provided between a position where the rear end of the transfer material is away from the conveyance roller of the loop-shaped conveyance path 41 and a time when the front end of the transfer material reaches the transfer position 20b. Preferably, the rear end of the transfer material has a loop-shaped conveyance path 41.
It is preferably provided between a position distant from the printer and a detection sensor 21b that detects the leading end of the transfer material.

The detection sensor 21b comprises a photo sensor or the like. The distance from the detection position of the detection sensor 21b to the transfer position 20b of the second image forming unit 15 and the image projection device 22b provided in the second image forming unit 15 The distance from the lighting position of the LED array to the transfer position 20b is provided to be substantially the same, and the detection sensor 21b detects the leading end of the transfer material, and the second image forming unit 15 By starting to turn on the LED array as the image projection device 22b provided, printing can be performed at a desired position on the transfer material without stopping the transfer material.

The second image forming section 15 has the same configuration as the first image forming section, that is, forms the second toner image with the second surface of the transfer material facing upward. It has a configuration using electrophotography, and has an image carrier such as a photosensitive drum or a photosensitive belt at the center thereof. Image carrier 25b
And one or more corona chargers or charging rollers 29b, which are charging rollers, for uniformly charging the surface of the image carrier 25b, and project the second document data read by a scanner or the like using an LED or the like. Image forming device 22b for forming a latent image on image carrier 25b, developing device 30b for supplying a charged toner to the latent image to form a second toner image, and first image forming unit 12 Device 31b for transferring the first toner image on the image carrier 25b to the second surface of the transfer material sent from the printer, and a cleaning device for removing the toner remaining on the surface of the image carrier 25b after the transfer 32b, and an eraser lamp 33b for uniformly eliminating the surface potential of the surface of the image carrier 25b. These are arranged so as to sequentially act on the image carrier 25b. Divide. An image is formed by a known image forming method. When a polymerized toner is used as the developer, the cleaning device 32b may be omitted.

The transfer device 31b has a plurality of transfer rollers 34 having different widths, and is provided so as to be rotatable about a fulcrum 35. The transfer roller 34 corresponds to the length of the transfer material to be used in the width direction. To contact the image carrier 25b or to contact the image carrier 25b via the transfer material. Further, the transfer roller 34 having a width slightly shorter than the width of the transfer material is selected according to the size of the transfer material to be used. In the illustrated example, five transfer rollers 34 are provided, but the number is not limited.

Reference numeral 36b denotes a fixing device 37 for transferring a transfer material carrying an unfixed second toner image formed on the second surface.
4A shows a transport belt that transports toward b. For example, a single wide endless belt extending over the entire width in the width direction of the transfer material of the maximum size, or a transport belt 36b including a plurality of endless belts appropriately divided in the width direction of the transfer material and arranged in parallel And a suction means 38b which acts to bring the transfer material into close contact with the transport belt 36b and transports it. A plurality of intake ports are provided at predetermined positions on the peripheral surface of the transport belt 36b, and an intake box having a large number of intake holes on an upper surface arranged in a space surrounded by the transport belt 36b is provided with suction means 38b such as a blower.
The transfer material is conveyed to the transfer belt 36b in close contact with the peripheral surface of the transfer belt 36b.

The transfer material on which the second toner image has been formed is
Next, the sheet is sent to the fixing device 37b. In the illustrated example, the fixing device 37b is a so-called heat fixing roller device including a heating roller 24b and a pressing roller 25b that are in pressure contact with each other, and the second transfer member is formed by passing a transfer material between these rollers.
Is heated and fixed on the transfer material.

The third transport path 17 is for discharging the transfer material fixed by the fixing device 37b from the image forming unit 3 toward the collecting unit 4, and in the illustrated example, after passing through the fixing device 37b. The transfer material is U-turned in the transport path, and then the transfer material is transported horizontally by the transport belt 42,
The stacking unit is further turned vertically upward to convey the transfer material in the vertical direction to the vicinity of the fixing device 37a, and then turned so as to be in the horizontal direction. The transfer material that has been double-sided copied is conveyed toward a discharge port 16 for discharging the transfer material to the outside. A common transport belt 43 is used for a part of the third transport path 17 so as to transport the back surface of the loop-shaped transport path.

The position of the discharge port 16 is the same as the position of the paper supply port so that the paper supply port 18 and the discharge port 16 can be easily connected when the image forming section 3 is unitized and a plurality of image forming units are connected. Provided at height. In the case of single-sided copying, after the transfer material has passed through the fixing device 37a, the transfer path 4 is switched by a switching unit (not shown) such as a switching claw.
1a is switched so that the path is short-cut, and the sheet is directly conveyed toward the discharge port 16 without passing through the second image forming section.

The stacking section 4 includes a first stacking table 44 provided above the stacking section 4 and a second stacking table 45 provided inside the stacking section 4.
And the inlet roller 4 communicating with the outlet 16 of the image forming section 3
6 and an upper transport path 47 and a lower transport path 48 for transporting the transfer material to the first stacking table 44 and the second stacking table 45. The transfer material discharged from the discharge port 16 of the image forming unit 3 passes through the inlet roller 46 and further passes through the upper transport path 47 or the lower transport path 48 in the stacking unit 4 so that the first surface is directed downward. The first stacking table 44 or the second
Is conveyed toward the stacking table 45.

At least one of the upper transport path 47 and the lower transport path 48 is provided with a transport path changing means 49 for changing the transport path in the width direction of the transfer material. The transport path changing means 49
For example, as shown in FIG. 4, a plurality of rollers 23 are provided obliquely with respect to the transfer direction of the transfer material, and a guide for contacting and guiding one side surface of the transfer material. It has a member 28. The transfer material is conveyed over rollers 23 provided diagonally, moves the transfer material in the horizontal direction, and after a predetermined amount of movement, the guide member 28 abuts against the side surface of the transfer material and moves further in the horizontal direction. Is regulated.

For example, the transport path changing means 4 is connected to the upper transport path 47.
When the number 9 is provided, the upper conveyance path 47 and the lower conveyance path 48 are switched by the desired number of sheets by the conveyance path switching means 49 provided near the entrance of the stacking section 4 and the first stacking table 44 or the second stacking means. It is discharged to the table 45. By this operation, the transfer material is discharged so as to be alternated for each set bundle, and the handling of the transfer material is improved.

The second stacking table 45 abuts the leading end of the transfer material against a guide plate 50 provided on the stacking table 45 to align the transfer materials at the time of stacking with the heads aligned. When the transfer material is ejected from the exit roller of the conveyance path when using a small-size transfer material, the driving force of the conveyance roller or the like is lost, and the leading end of the transfer material does not reach the guide plate and is accumulated on the way. Having. In particular, the leading end of the next transfer material abuts against the trailing end of the previously transferred small-sized transfer material, and stacking in a state where the leading ends are aligned is not performed. For this purpose, a suction conveyance unit 51 for suctioning and transferring the transfer material output from the discharge port with a suction belt, and a swingable pressing unit 52 for pressing the transfer material are provided. Also, the second stacking table 45
Has an elevator mechanism for adjusting the height of the uppermost surface due to the accumulation of the transfer material, and detects a change in the tip position due to the swing of the pressing means 52, and moves the mounting table downward.

The suction / conveying means 51 may be a single wide endless belt extending over the entire width of the maximum-size transfer material or a plurality of parallel-divided and suitably arranged in the width direction of the transfer material. The transfer belt 54 includes an endless belt, and a suction unit 55 that works so as to bring the transfer material into close contact with the transfer belt 54 and transports the transfer material. A plurality of intake ports are provided at predetermined positions on the peripheral surface of the conveyor belt 54, and an intake box having a number of intake holes on a lower surface arranged in a space surrounded by the conveyor belt 54 and a suction unit 55 such as a blower being ducted. Then, air is sucked from the air inlets toward the inside of the conveyor belt 54 to convey the transfer material in close contact with the peripheral surface of the conveyor belt 54. At this time, by providing the transport distance between the upper transport path 47 and the lower transport path 48 to be the same, the above-described suction of the transfer material can be performed at the same timing.

The first and second images to be reproduced in the first image forming unit 12 and the second image forming unit 15 are:
It may be based on image information stored in advance in storage means such as a computer, or may be based on read data obtained by reading an individual document by an image reading means such as an image scanner or OCR.

When the image reading means is used, for example, a scanner equipped with an automatic document feeder is used.
The automatic document feeder sends the document placed on the tray to the
These are supplied to the image reading unit of the scanner in order one by one.
The sent document is sequentially read by the reading section, and is output to the first image forming section 12 and the second image forming section 15 by a control section via an appropriate storage means or directly.

Normally, image data of an odd-numbered document is sent to and output from the image projecting device 22a, and image data of an even-numbered document is sent to the optical projecting device 22b.
As a result, the transfer material output to the first stacking table 44 or the second stacking table is stacked with the pages aligned.

The image forming section 3 includes a first regulating means 1.
0, the first image forming unit 12, the second regulating unit 13, the second
The image forming units 15 are unitized, and drive transmission means such as a gear mechanism or a belt pulley mechanism for driving the unit is detachably provided on either end of the drive shaft at both ends of the unit. , At least one of which is provided with a drive transmission means and is connected to a drive source provided on the same side of the apparatus main body. Such drive shafts include first and second drive shafts.
For example, in the image forming section, the drum shaft of the drum-shaped image carrier is used, and in the first and second regulating means, the transport roller shaft or the support shaft of the transport belt is used. With such a configuration, the first image forming unit 12 and the second image forming unit 15 are interchangeable, and the first regulating unit 10 and the second regulating unit 13 are interchangeable. Has become. In addition, the fixing devices 37a and 37b and the transport belts 36a and 36b may be provided as a unit so that they can be replaced in the same manner as described above.

For example, when exchanging the units of the regulating means 10 and 13, the driving means provided on one of the drive shafts of the first regulating means 10 is provided so as to be able to be pulled out in the axial direction from the side of the apparatus main body. A guide plate for aligning one side of the laterally displaced transfer material is replaced with a shaft, and the guide plate is replaced with a position on the opposite side, and arranged at the position of the second regulating means 13. The first regulating unit 10, the second regulating unit 13, the first image forming unit 12, the second image forming unit 15, the fixing devices 37a and 37b, the transport belts 36a and 3
6b and the like can be replaced from one side surface of the apparatus main body, so that handling is improved.

The operation of such a configuration will be described. The transfer material selected from the paper feed unit 2 in accordance with an instruction from a control unit (not shown) based on an operator's instruction is picked up one by one by one of the paper feed rollers 6a, 6b, and 6c and passed through the transport unit 9. The sheet is conveyed to the image forming unit 3. The transfer material conveyed to the image forming unit 3 is corrected by the first restricting means 10 to correct a lateral shift at the time of pick-up of the paper feed rollers 6a (6b, 6c) or a transfer material skewed during the conveyance period of the conveyance means 9. While transporting the first image forming unit 1
The sheet is conveyed to the first image forming unit 12 in a direction orthogonal to the second image carrier 25a.

In the first image forming section 12, a first toner image formed on the image carrier 25a by a known image forming method is transferred to a first surface of a transfer material via a transfer roller. In order to match the registration between the toner image formed on the image carrier 25a and the transfer material, the leading end of the transfer material is detected by the detection sensor 21a provided in the middle of the conveyance path, and the image projection device 22a is activated at a predetermined timing. Let it. As the transfer roller 34, a transfer roller having a width slightly shorter than the size of the transfer material in the width direction is selected in advance. Next, the transfer material on which the first toner image is formed is conveyed while being suctioned onto the conveyance belt 36a by the suction means 38a, and is conveyed to the fixing device 37a to be fixed. In addition to the suction of the transfer material, the transport belt 36a has a function of sucking heat generated from the fixing device 37a and discharging the heat to the outside of the device. Discharge of such heat is also important for protection of the image carrier.

The transfer material on which the first toner image has been fixed passes through the loop-shaped conveyance path 41, passes through the second regulating means 13 with the second surface as the upper surface, and is transferred to the second image forming section 15. It is conveyed toward. The skew of the transfer material is corrected by the second regulating unit 13, and the transfer position 20 b of the second image forming unit 15 is adjusted.
Will be guided to. To match the registration between the toner image formed on the image carrier 25b and the transfer material, the leading end of the transfer material is detected by a detection sensor 21b provided in the middle of the conveyance path, and the image projection device 2 is activated at a predetermined timing.
2b is operating. As the transfer roller 34, a transfer roller having a width slightly shorter than the size of the transfer material in the width direction is selected in advance.

Next, the surface of the transfer material on which the second toner image has been formed is conveyed to the fixing device 37b while being conveyed by the conveyance belt 36b by suction means 38b. The transfer material has the first toner image and the second toner image fixed thereon by the fixing device 37b, and then is transported by the third transport path 17 to be transported from the image forming unit 3 to the stacking unit 4.

The transfer material guided to the stacking section 4 is transported by an operator to a transport path of either the upper transport path 47 or the lower transport path 48, and the transfer material is transferred to either the first stacking table 44 or the second stacking table 45. Crabs are collected neatly. When it is desired to stack transfer materials alternately, the upper transport path 47 and the lower transport path 48 are switched for each desired number of sheets and the upper transport path 47 is switched.
The transfer direction of the transfer material is shifted in the width direction by the
At the first stacking table 44 or the second stacking table.
Is discharged to the collecting table 45. The second stacking table 45 holds the upper surface of the transfer material discharged by the suction conveyance unit with the suction unit 55.
The sheet is conveyed by the conveying belt 54 and is guided by the swinging of the pressing means 52 so as to abut against the guide plate 50 provided on the stacking table to be stacked.

The image forming section 3 having the first image forming section 12 and the second image forming section 15 is connected to the sheet feeding section 2 and the stacking section 4.
And a plurality of them, and pass through the above-described transport path,
A color image is formed on both sides of the transfer material and discharged to the stacking unit. If necessary, the transfer material may be discharged from a discharge port in the middle and collected on a collecting tray provided above the image forming unit.

FIG. 1 is an example of the arrangement of the main constituent elements of the present invention, and the sizes and the ratios of the dimensions shown in the drawings are not limited. The first toner image on the transfer material may be fixed at a normal fixing temperature by the fixing device 37a.

[0052]

According to such a configuration, the regulating means for correcting the skew or lateral displacement of the transfer material before being guided by the first image forming unit and the second image forming unit is provided, so that it is always constant. The printing position can be ensured, the possibility of occurrence of jam is extremely reduced, the image forming speed can be maximized, and high-speed double-sided copying or double-sided printing can be performed on a large number of sheets. Further, by providing the regulating means so as to be substantially horizontal and longer than the length of the maximum size transfer material, the deflection of the transfer material can be minimized, and skew or lateral displacement can be corrected at high speed. .

Further, the first image forming unit and the second image forming unit, the first regulating unit and the second regulating unit, the transport path, and the like are unitized, and the same unit can be replaced so that maintenance can be performed. Operability such as inspection can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an image forming apparatus according to the present invention.

FIG. 2 is a schematic diagram showing an example of a regulating unit.

FIG. 3 is a schematic view showing an example of another regulating means.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 image forming apparatus 2 paper feeding unit 3 image forming unit 4 stacking unit 5a, b, c paper feeding table 6a, b, c paper feeding roller 7a, b, c lift 8 exit 9 transport means 10 first regulating means 11th 1 transport path 12 first image forming unit 13 second regulating means 14 second transport path 15 second image forming unit 16 discharge port 17 third transport path 18 paper feed port 19 paper feed roller pair 20a b Transfer position 21a, b Detection sensor 22a, b Image projection device 23 Conveying roller 24 Conveying belt 25a, b Image carrier 26 Ball 27 Roller 28 Guide member 29a, b Charging device 30a, b Developing device 31a, b Transfer device 32a, b cleaning device 33a, b eraser lamp 34 transfer roller 35 fulcrum 36a, b transport belt 37a, b fixing device 38a, b suction means 39a, b heating roller 40a, b Pressure rollers 41a, b Conveying path 42 Conveying belt 43 Conveying belt 44 First collecting table 45 Second collecting table 46 Inlet roller 47 Upper conveying path 48 Lower conveying path 49 Conveying path changing means 50 Guide plate 51 Suction Conveying means 52 Pressing means 53 Mounting table 54 Conveying belt 55 Suction means 56 Discharge port 80 Gear 90 Drive source

Claims (5)

[Claims] 1. A first image forming unit for forming a first toner image with a first surface of a transfer material facing upward, and the first surface facing downward on the downstream side of the first image forming unit. And a second image forming section for forming a second toner image with the second surface of the transfer material facing upward, and a first image. Forming part and second
In the image forming apparatus in which each of the image forming units has a fixing device, the position between the sheet feeding position of the transfer material conveyed from the sheet feeding unit and the transfer position of the first image forming unit is substantially horizontal and has a maximum size. A first conveying path provided with a longer distance than the transfer material and having first regulating means for restricting the lateral displacement of the transfer material, and a first surface of the transfer material formed by the loop-shaped conveying path. Is provided in a substantially horizontal direction from the position where the is downward to the transfer position of the second image forming unit, and is provided so as to be longer than the transfer material of the maximum size, thereby restricting the lateral displacement of the transfer material that may occur therebetween. An image forming apparatus comprising: a second conveyance path including a second regulating unit. 2. The image forming apparatus according to claim 1, wherein each of the first and second regulating units regulates one side edge of the transfer material as a reference. 3. The image forming apparatus further comprises a third conveying path for discharging the transfer material to the outside of the second image forming unit so that the first surface of the transfer material faces downward downstream of the second fixing device. The image forming apparatus according to claim 1, further comprising: 4. The first restricting means and the second restricting means are unitized, and a drive transmitting means for driving these units is detachably provided on either end of a drive shaft of the unit. The drive transmission means is provided on at least one of the two ends so that the drive transmission means can be connected to a drive source provided on the same side of the apparatus main body, so that the first restriction means and the second restriction means are interchangeable. The image forming apparatus according to claim 1, wherein: 5. The first image forming section and the second image forming section are formed as a unit, and a drive transmitting means for driving these units can be detachably attached to either end of a drive shaft of the unit. The first image forming unit and the second image forming unit are provided with the drive transmission means on at least one of both ends thereof so as to be connectable to a drive source provided on the same side of the apparatus main body. The image forming apparatus according to claim 1, wherein the image forming apparatus is interchangeable.