JPH11327220A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device where the jamming of sheet material is reduced, by which double-sided copying and double-sided printing can be performed at a high speed and which is excellent in handleability. SOLUTION: This device is equipped with a 1st image forming part 3 forming a 1st toner image for one surface of the sheet material, a 1st carrying means 4 carrying the sheet material while carrying the surface of the sheet material being an opposite side to the surface where the 1st toner image is formed, a 1st fixing device 5 fixing the 1st toner image, a 2nd image forming part 6 forming a 2nd toner image for the other surface of the sheet material, a 2nd carrying means 7 carrying the sheet material while sucking the surface of the sheet material being a side where the 1st toner image is formed and a 2nd fixing device 8 fixing the 2nd toner image. A sheet material carrying path is provided to be nearly linear and also a 2nd carrying path 33 is provided at the poststage of the 1st fixing device 5 separately from the sheet material carrying path so that it can be switched by a switching means 32.

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 sheet material.

[0002]

2. Description of the Related Art As a model of an image forming apparatus such as a copying machine and a printer, an apparatus capable of forming an image on both the front and back surfaces of one sheet material has been proposed. Such an apparatus generally known includes forming a first image on one surface of a sheet material, and temporarily storing the sheet material in a tray for turning over the sheet, called an intermediate tray, provided in the image forming apparatus. Then, the sheet 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 where the first image was formed, where the second image is formed on a different surface of the sheet material. Is formed and then discharged outside the image forming apparatus.

Such an apparatus may be used for a relatively slow operation in which two developments are reproduced one by one on the front and back surfaces of one sheet 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. .

One of them is a jam at the time of re-feeding from the intermediate tray. When a large number of originals are continuously copied on both sides, first, even originals among the originals to be reproduced are skipped. Only the image of the odd document is formed on one side of the sheet material, the sheet material having the image formed on one side thereof is temporarily loaded on the intermediate tray, and then re-fed for forming the image of the odd document. However, in many cases, when forming an odd-numbered document, the sheet material is attracted to adjacent sheet materials by electrostatic attraction by a corona charger or the like at the time of image formation. When the paper is re-fed, the paper is often double-fed and jams easily occur.

Further, in the above-described configuration, open timing control is required during the stage of temporarily loading and storing the sheet material in the intermediate tray and then re-feeding the sheet material. It is not suitable for continuous copying and printing, and is difficult to cope with. Further, when the sheet material is a large-sized sheet, an intermediate tray having a size corresponding to the large-sized sheet is required, and there is a restriction on the compactness of the apparatus.

On the other hand, 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 an upper surface and a lower surface of a sheet material so that 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 sheet material conveyance path is substantially U-shaped.

In the image forming apparatus having such a configuration, the conveying path of the sheet material is U-shaped by a conveying roller or the like. For this reason, especially when high-speed copying is performed, there are problems to be solved such as displacement of the sheet material and registration with the next image forming means. Also,
In the case where a paper jam occurs at the time of speeding up image formation, the image forming apparatus cannot be immediately stopped because the next sheet material continuously performs the image forming operation. In some cases, only one side of a two-sided copy is output as a test.

Further, in the transfer section of the image forming means, as the diameter of the image carrier increases, the curvature of the image carrier increases, and a means for separating the passing sheet material from the image carrier is required. For example, it is necessary to provide a plurality of separation claws in contact with the image carrier and to peel off the transfer material. As a result, a case may occur in which the peeling claw on the image carrier causes a scratch or a sheet material jams.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems, and has an advantage in that a sheet material is extremely free of jams, high-speed double-sided copying and double-sided printing are possible, and single-sided printing is possible. It is an object of the present invention to provide an image forming apparatus capable of minimizing the influence on the next sheet material even when test printing or a jam occurs.

[0010]

In order to solve the above problems, an image forming apparatus according to the present invention is provided with a first conveying path for a sheet material in a substantially horizontal direction from an input port to an output port of the sheet material.
A first image forming unit that forms a first toner image on one surface of the sheet material along the first conveyance path;
A first conveying unit configured to support and convey a surface of the sheet material opposite to a surface on which the first toner image is formed;
A first fixing device for fixing the first toner image, a second image forming section for forming a second toner image on the other surface of the sheet material, and a first fixing device for fixing the first toner image. A second conveying unit that receives and conveys the surface of the sheet material and a second fixing device that fixes the second toner image are sequentially arranged, and the sheet material that has passed through the first fixing device is further disposed. A second transport path switchably provided with the first transport path for discharging to a tray outside or inside the apparatus without being sent to the second image forming unit, and for one side or both sides of a copying machine or print And a switching unit for switching between the two transport paths.

The first image forming section and the second image forming section each include an image carrier for forming a toner image and a transfer roller opposed via the first transport path. The first image forming section and the second image forming section each include an image carrier that forms a toner image, and a toner image that is in contact with the image carrier and is placed on one surface of a sheet material. And a transfer roller that conveys the transfer roller and a transfer roller that faces the intermediate transfer roller via the first conveyance path.

Further, the second conveyance path extends upward with respect to the first conveyance path, and discharges a sheet material to an upper portion of the apparatus main body. When a jam occurs in any of the second conveying unit and the second fixing device, the sheet material to be conveyed next is switched to the second conveying path and discharged to a tray outside or inside the device. It is characterized by having switching control means for performing the switching.

Still further, the image forming apparatus includes a first unit including a first image forming unit, a first conveying unit, and a first fixing device, a second image forming unit, and a second conveying unit. Means and a second unit including a second fixing device, wherein the first unit and the second unit are provided so as to be separable, and the second unit is provided in the second unit. A transport path and the tray are provided.

With this configuration, the sheet material forms the first toner image on one surface by the first image forming hand along the first transport path having the linear transport path.
After passing through the first fixing device, the first toner image is fixed. Next, the sheet material is conveyed to the second image forming section to form a second toner image on the other surface, and is conveyed to the second fixing device by the second conveying means to be fixed. The sheet material on which the first and second toner images have been formed on the front and back surfaces is discharged to the outside of the image forming apparatus.

On the other hand, when a trouble such as a paper jam occurs in the process after the second image forming section or when it is desired to perform test printing on only one side, the switching control means causes the second conveying path to move from the first conveying path to the second conveying path. Switch to the transport path, and the sheet material is
Without passing through the process after the image forming section.

[0016]

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 is roughly divided into a sheet feeding unit 2 for sheet material, a first image forming unit 3 for forming a first toner image on one surface of the sheet material, and a first conveyance for conveying the sheet material. Means 4, a first fixing device 5 for fixing the first toner image, a second image forming unit 6 for forming the second toner image on the other surface of the sheet material, and a second image forming unit 6 for conveying the sheet material. A second fixing unit 8 for fixing the second toner image, and a stacking unit 9 for stacking sheet materials on which front and back images have been formed. The first image forming unit 3, the first conveying unit 4, the first fixing device 5, the second image forming unit 6, the second conveying unit 7, and the second fixing device 8 have a sheet material conveying path. They are arranged so as to be substantially straight. Further, in addition to these components, it is desirable to arrange the sheet feeding unit 2 and the stacking unit 9 linearly, and the sheet material conveyance path is the first conveyance path.

In this example, the sheet feeding unit 2 shows a sheet type configuration, and moves a sheet material stacking table 11 on which a large number of sheet materials 10 are stacked in the direction of an arrow A in an elevator manner as it is consumed by image formation. Thus, the top end of the sheet material is kept at a constant height. Further, a type in which roll paper is cut and used may be used, or a configuration in which a plurality of paper feed cassettes or paper feed decks are provided in the image forming apparatus, and different types are provided in the cassettes or on the upper surfaces of the decks, respectively. A type in which sheet materials of a size are stacked may be used.

The sheet material is fed in accordance with a command from a control unit based on an operator's command. For feeding the sheet material, a sheet feeding roller 12 is disposed so as to face the uppermost sheet material of the stacked sheet materials, and the sheet feeding roller 12 is driven to drive the uppermost sheet material of the sheet material. Is separated from the second and subsequent sheet materials and fed to the first image forming unit 3.

The sheet material fed by the feed roller 12 is conveyed to a pair of registration rollers 14 that have stopped rotating through a pair of conveyance rollers 13, and the pair of registration rollers 14.
The registration roller pair 14 starts to rotate at the timing of the toner image on the rotating image carrier 15a of the first image forming unit, which will be described in the next order, and the first image formation is performed. It is sent to the transfer section 29 of the section 3. Alternatively, the conveying roller pair 13 and the registration roller pair 14 may be used together.

In the illustrated example, the first image forming section 3 has a configuration utilizing electrophotography, and has an image carrier such as a photosensitive drum or a photosensitive belt at the center thereof. A corona charger 16a or a charging roller for uniformly charging the surface of the image carrier 15a around the image carrier 15a, and the first document data read by a scanner or the like are projected by an LED or the like to project the image carrier. Optical projection device 1 for forming a latent image on 15a
7a, a developing device 18a for supplying a charged toner to the latent image to form a first toner image, and one surface of the sheet material sent from the paper feeding unit 2 (the lower surface in the figure) A transfer roller 19a for transferring the first toner image on the image carrier 15a, a cleaning device 20a for removing toner remaining on the surface of the image carrier 15a after the transfer, and a surface potential of the surface of the image carrier 15a. And an eraser lamp 21a for uniformly removing the charges, and these are arranged so as to sequentially act on the image carrier 15a, and an image is formed as is well known.

The first conveying means 4 conveys a sheet material having a first toner image formed on the lower surface thereof to a first fixing device 5 to be described later.
a and suction means 23a for conveying the sheet material in such a manner as to be brought into close contact with the conveying belt 22a. A plurality of air inlets are provided at predetermined positions on the peripheral surface of the conveyor belt 22a, and are connected to suction means 23a such as a blower via a duct, and air is sucked from these air inlets toward the inside of the conveyor belt 22a to perform sheet suction. Is transported in close contact with the peripheral surface of the transport belt 22a. In particular, when the sheet material passes through the transfer unit 29 of the first image forming unit 3, a downward force is applied due to the weight of the sheet material and the sheet material tends to move along the surface of the image carrier. It is desirable to provide a means near the transfer unit 29, and the sheet material is conveyed while being sucked immediately after the sheet material has passed through the transfer roller 19a.

The sheet material on which the first toner image is formed on the lower surface is then sent to the first fixing device 5. In the illustrated example, the first fixing device is a heating roller 2 pressed against each other.
The first toner image is heated and fixed to the sheet material by passing the sheet material between these rollers, which is a so-called heat fixing roller device including the pressure roller 4a and the pressure roller 25a.

The temperature of the first fixing device 5 is set to a low fixing temperature at which the first toner image does not scatter. The fixing temperature is controlled by the second image forming unit 6 and the second image forming unit 6.
Are set to such an extent that they do not contaminate these peripheral devices and do not disturb the first toner image. The first toner image is fixed together with the second toner image in a state where there is no problem when passing through a second fixing device 8 described later.

The second image forming section 6 has the same structure as the first image forming section 3, that is, a corona charger for uniformly charging the surface of the image carrier 15b around the image carrier 15b. 16b or a charging roller, and an optical projection device 17b for projecting the second document data read by a scanner or the like with an LED or the like to form a latent image on the image carrier 1;
A developing device 18b for supplying a charged toner to the latent image to form a second toner image and the other surface (upper surface as viewed in the drawing) of the sheet material sent from the first fixing device 5 A transfer roller 19b for transferring the second toner image on the image carrier 15b, a cleaning device 20b for removing toner remaining on the surface of the image carrier 15b after the transfer, and a surface potential of the surface of the image carrier 15b. And an eraser lamp 21b for uniformly removing charges, which are arranged so as to sequentially act on the image carrier 15b, and perform image formation as is well known.

The second conveying means 7 has the same structure as the first conveying means 4, and conveys the sheet material having the second toner image formed on the upper surface thereof to the second fixing device 8. . For example, a conveying belt 22b and a suction unit 2 that acts to convey the sheet material in close contact with the conveying belt 22b and convey the sheet material.
3b. A plurality of suction ports are provided at predetermined positions on the peripheral surface of the conveyor belt 22b, and suction means 23b such as a blower is provided.
Then, air is sucked from these air inlets toward the inside of the transport belt 22b, and the sheet material is transported in close contact with the peripheral surface of the transport belt 22b.

The second fixing device 8 has the same structure as the first fixing device 5. In the illustrated example, the second fixing device comprises a heating roller 24b and a pressure roller 25b which are in pressure contact with each other.
A second toner image is heat-fixed to the sheet material by passing the sheet material between the rollers, and the first toner fixed by the first fixing device 5 to such an extent that the second toner image does not scatter. The image is heat-fixed again and discharged outside the apparatus.

The first and second images to be reproduced in the first image forming unit 3 and the second image forming unit 6 may be based on image information previously stored in storage means such as a computer. Alternatively, each original may be read by image reading means such as an image scanner or an OCR, and based on the read data.

When the image reading means is used, for example, a scanner having 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 3 and the second image forming section 6 by a control section via appropriate storage means or directly.

Normally, the image data of the odd-numbered original is sent to the optical projection device 17a for output, and the even-numbered image data is sent to the optical projection device 17b.

In this example, the sheet material stacking section 9 stacks the sheet materials discharged after the completion of image formation. For example, the stacking section 9 is capable of vertically moving the continuously discharged sheet materials. The stacking table 26 is moved to the direction indicated by the arrow B so that the height of the stacked sheets is constant. At the time of image formation, the stacking platform 11 of the sheet feeding unit 2 and the stacking platform 26 of the stacking unit 9 are interlocked, and one of the stacking platforms is moved and used based on a signal obtained by adjusting one of the heights. . Reference numeral 30 denotes an abutting member that abuts the leading edge of the sheet material during ejection to align the leading edge of the sheet material.

Further, the image forming apparatus 1 includes a first unit 27 including a first image forming unit 3, a first conveying unit 4, and a first fixing unit 5, a second image forming unit 6, A second unit 28 including the second transport unit 7 and the second fixing device 8
And a first unit 27 and a second unit 28
And are provided in a separable manner, and can be treated as separate bodies. Thus, when two-sided copying is desired, the first unit 27 and the second unit 28 are used in combination.

On the other hand, a first conveying path which is switchably provided with a first conveying path for discharging the sheet material passing through the first fixing device 5 to a tray outside or inside the apparatus without sending the sheet material to the second image forming section 6. Switching means 3 for switching between two transport paths according to two transport paths 33 and one side or both sides of a copier or a print machine.
And 4. In the illustrated example, the switching unit is located behind the first fixing device 5, and a known method can be applied. For example, the tip of the substantially triangular switching unit is rotated by a predetermined angle and the conveyance path is rotated. Has changed. Second transport path 33
Extends upward with respect to the first transport path, and continues to a tray 34 provided on an upper portion of the apparatus main body for loading sheet materials. The switching means switches via the operation panel in accordance with an operator's instruction when performing only one side of copying or printing. Alternatively, the switching control means (not shown)
If a trouble such as a paper jam occurs in the image forming section of
A sensor provided on the first transport path detects an abnormality and switches from the first transport path to the second transport path.

The operation of the above configuration will be described. The sheet material is fed from the sheet feeding unit 2 in accordance with an instruction from a control unit (not shown) based on an operator's instruction, and the registration roller pair 14 rotates with the timing of the first toner image in the first image forming unit 3. And sheet material first
Is conveyed to the image forming unit 3. In the first image forming unit 3, the first toner image formed on the image carrier 15a by a known image forming method is transferred to the lower surface of the sheet material via the transfer roller 19a. Next, the upper surface of the sheet material on which the first toner image is formed is conveyed to the first fixing device 5 while being conveyed by the conveyer belt 22a serving as the first conveyer unit 4 by the suction unit 23a.

The sheet material is fixed by the first fixing device 5 at a fixing temperature at which the first toner image is not scattered, and is conveyed from the first unit 27 to the second unit 28. In the second image forming section 6, the second toner image formed on the image carrier is transferred onto the upper surface of the sheet material by a known image forming method at a timing at which the sheet material is conveyed. Next, the surface of the sheet material on which the first toner image has been formed is conveyed to the second fixing device 8 while being conveyed by the conveyance belt 22b as the second conveyance means 7 by suction means 23b.

In the second fixing device 8, the second toner image formed on the sheet material by sufficient heat and the first toner image in an incomplete state that has passed through the first fixing device 5 are fixed. It is discharged toward the stacking unit 9 provided outside the second unit 28.

On the other hand, when only one side of copying or printing is performed, switching is performed so that the sheet material is guided from the first conveying path to the second conveying path in accordance with an instruction from a control panel or the like by the operator, or a second image is formed. When a trouble such as a paper jam occurs in the forming unit, a sensor (not shown) detects an abnormality and switches from the first conveyance path to the second conveyance path. The sheet material is conveyed along the second conveyance path, and is discharged to a tray 34 provided at an upper portion of the apparatus main body.

FIG. 2 shows another embodiment. FIG. 2 illustrates a configuration including an intermediate transfer roller in the configuration of the first and second image forming units illustrated in FIG. 1. In the illustrated example, the intermediate transfer roller 31a that presses the image carrier 15a to move the first toner image on the image carrier 15a, and the image carrier 1
An intermediate transfer roller 31b that moves the second toner image on the image carrier 15b by pressing the intermediate transfer roller 31b is provided.

The intermediate transfer rollers 31a and 31b have a smaller diameter than the image carriers 15a and 15b.
a and 19b have substantially the same diameter. The sheet material is supplied to the intermediate transfer rollers 31a and 3a set at an appropriate pressing force.
The first toner image on the intermediate transfer rollers 31a and 31b is transferred between the transfer rollers 1a and the transfer rollers 19a and 19b. Even if the leading edge of the sheet material passes through the sheet material, the diameter of both rollers is small.
a, 31b or the transfer rollers 19a, 19b.
It is carried on.

In FIG. 2, the sheet material that has passed through the first first fixing device is not sent to the second image forming section but is fed to the outside of the apparatus or to the inside of the apparatus with respect to the linearly provided first conveyance path. And a switching means for switching between two transport paths according to one side or both sides of a copier or a print machine.
In the illustrated example, a switching unit 32 for switching the transport path from the first transport path behind the first fixing device 5 and a second unit 2 extending downward with respect to the first transport path.
A second transport path 33 extending toward the sheet feeding unit 8 and a tray 34 provided in the second unit 28 for stacking sheet materials are provided. The sheet materials accumulated on the tray 34 can be obtained by, for example, being provided so as to be able to be pulled out to the near side as viewed in the drawing.

The switching means 33 switches via the operation panel in accordance with an operator's instruction when performing only one side of copying or printing. Alternatively, when a trouble such as a paper jam occurs in the second image forming unit as a switching control unit, this state is detected by a sensor (not shown) and the first conveyance path is switched to the second conveyance path.

Although the first toner image is formed on the lower surface of the sheet material and the second toner image is formed on the upper surface of the sheet material, the first toner image is formed by the first image forming unit. May be formed on the upper surface of the sheet material, and then the second image forming unit forms the second toner image on the lower surface of the sheet material. FIG. 1 is an example of the arrangement of the components, and the size of each component is not limited.

[0041]

As described above, when only one side of copying or printing is performed, switching can be performed according to the instruction of the operator. Alternatively, when a trouble such as a paper jam occurs in the second image forming unit as a switching control unit, this state is detected by a sensor (not shown) and the state is switched from the first conveyance path to the second conveyance path. With the configuration in which the sheet material is transported along the second transport path and accumulated on the tray,
An easy-to-use image forming apparatus can be provided. In particular, even if a trouble occurs in the second image forming unit, the next sheet material is not adversely affected. Further, since the sheet material is conveyed almost linearly in the image forming apparatus, the sheet material can be conveyed without forcing the sheet material, thereby greatly reducing the possibility of jamming and reducing the image forming speed. Can be as fast as possible.

[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 sectional view showing another example of the image forming apparatus according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image forming apparatus 2 paper feeding unit 3 first image forming unit 4 first transport unit 5 first fixing device 6 second image forming unit 7 second transport unit 8 second fixing device 9 stacking unit 10 Sheet material 11 Stacking table 12 Paper feed roller 13 Transport roller pair 14 Register roller pair 15a, b Image carrier 16a, b Corona charger 17a, b Optical projection device 18a, b Developing device 19a, b Transfer roller 20a, b Cleaning device 21a, b Eraser lamp 22a, b Conveyor belt 23a, b Suction means 24a, b Heating roller 25a, b Pressure roller 26 Stacker 27 First unit 28 Second unit 29 Transfer unit 30 Abutment member 31a, b Intermediate Transfer roller 32 switching means 33 second transport path 34 tray

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 29, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Image forming apparatus

[Claims]

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 sheet material.

[0002]

2. Description of the Related Art As a model of an image forming apparatus such as a copying machine and a printer, an apparatus capable of forming an image on both the front and back surfaces of one sheet material has been proposed. Such an apparatus, which is generally known, forms a first image on one surface of a sheet material, and then temporarily stores the sheet material in a tray for inverting the sheet called an intermediate tray provided in the image forming apparatus. Then, the sheet 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 formed on a different surface of the sheet material. Is formed and then discharged outside the image forming apparatus.

Such an apparatus may be used for a relatively slow operation in which two developments are reproduced one by one on the front and back surfaces of one sheet 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. .

One of them is a jam at the time of re-feeding from the intermediate tray. When a large number of originals are continuously copied on both sides, first, even originals among the originals to be reproduced are skipped. Only the image of the odd document is formed on one side of the sheet material, the sheet material having the image formed on one side thereof is temporarily loaded on the intermediate tray, and then re-fed for forming the image of the odd document. However, in many cases, when forming an odd-numbered document, the sheet material is attracted to adjacent sheet materials by electrostatic attraction by a corona charger or the like at the time of image formation. When the paper is re-fed, the paper is often double-fed and jams easily occur.

Further, in the above-described configuration, open timing control is required during the stage of temporarily loading and storing the sheet material in the intermediate tray and then re-feeding the sheet material. It is not suitable for continuous copying and printing, and is difficult to cope with. Further, when the sheet material is a large-sized sheet, an intermediate tray having a size corresponding to the large-sized sheet is required, and there is a restriction on the compactness of the apparatus.

On the other hand, 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 an upper surface and a lower surface of a sheet material so that 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. Further, the sheet material conveyance path is defined by the first image forming unit and the second image forming unit.
It has a substantially U-shape between conveyance rollers and the like.

In an image forming apparatus having such a configuration,
Especially in the case of high-speed copying, in the U-shaped transport path
There is a problem to be solved, such as displacement of the sheet material at the time of registration, registration with the next image forming means, and the like. Further, in the case where a paper jam occurs at the time of increasing the speed of image formation, the image forming operation cannot be immediately stopped because the next sheet material is continuously performing the image forming operation. In some cases, only one side of a two-sided copy is output as a test.

Further, in the transfer section of the image forming means, the larger the diameter of the image carrier, the smaller the curvature of the peripheral surface of the image carrier.
This requires a means for separating the passing sheet material from the image carrier. For example, place the separation claw near the image carrier.
At a plurality of places, the transfer material is to be peeled off, but there is a problem that the sheet material is caught by the peeling claw and paper jam occurs.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems, and has an advantage in that a sheet material is extremely free of jams, high-speed double-sided copying and double-sided printing are possible, and single-sided printing is possible. It is an object of the present invention to provide an image forming apparatus capable of minimizing the influence on the next sheet material even when test printing or a jam occurs.

[0010]

In order to solve the above problems, an image forming apparatus according to the present invention is provided with a first conveying path for a sheet material in a substantially horizontal direction from an input port to an output port of the sheet material.
A first image forming unit that forms a first toner image on one surface of the sheet material along the first conveyance path;
A first conveying unit configured to support and convey a surface of the sheet material opposite to a surface on which the first toner image is formed;
A first fixing device for fixing the first toner image, a second image forming section for forming a second toner image on the other surface of the sheet material, and a first fixing device for fixing the first toner image. A second conveying unit that receives and conveys the surface of the sheet material and a second fixing device that fixes the second toner image are sequentially arranged, and the sheet material that has passed through the first fixing device is further disposed. A second transport path switchably provided with the first transport path for discharging to a tray outside or inside the apparatus without being sent to the second image forming unit, and for one side or both sides of a copying machine or print And a switching unit for switching between the two transport paths.

The first image forming section and the second image forming section each include an image carrier for forming a toner image and a transfer roller opposed via the first transport path. The first image forming section and the second image forming section each include an image carrier that forms a toner image, and a toner image that is in contact with the image carrier and is placed on one surface of a sheet material. And a transfer roller that conveys the transfer roller and a transfer roller that faces the intermediate transfer roller via the first conveyance path.

Further, the second conveyance path extends upward with respect to the first conveyance path, and discharges a sheet material to an upper portion of the apparatus main body. When a jam occurs in any of the second conveying unit and the second fixing device, the sheet material to be conveyed next is switched to the second conveying path and discharged to a tray outside or inside the device. It is characterized by having switching control means for performing the switching.

Still further, the image forming apparatus includes a first unit including a first image forming unit, a first conveying unit, and a first fixing device, a second image forming unit, and a second conveying unit. Means and a second unit including a second fixing device, wherein the first unit and the second unit are provided so as to be separable, and the second unit is provided in the second unit. A transport path and the tray are provided.

With this configuration, the sheet material forms the first toner image on one surface by the first image forming unit along the first transport path having the linear transport path, and And fixes the first toner image.
Next, the sheet material is conveyed to the second image forming section to form a second toner image on the other surface, and is conveyed to the second fixing device by the second conveying means to be fixed. The sheet material on which the first and second toner images have been formed on the front and back surfaces is discharged to the outside of the image forming apparatus.

On the other hand, when a trouble such as a paper jam occurs in the process after the second image forming section or when it is desired to perform test printing on only one side, the switching control means causes the second conveying path to move from the first conveying path to the second conveying path. Switch to the transport path, and the sheet material is
Without passing through the process after the image forming section.

[0016]

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 is roughly divided into a sheet feeding unit 2 for sheet material, a first image forming unit 3 for forming a first toner image on one surface of the sheet material, and a first conveyance for conveying the sheet material. Means 4, a first fixing device 5 for fixing the first toner image, a second image forming unit 6 for forming the second toner image on the other surface of the sheet material, and a second image forming unit 6 for conveying the sheet material. A second fixing unit 8 for fixing the second toner image, and a stacking unit 9 for stacking sheet materials on which front and back images have been formed.

The transfer position of the first image forming unit 3, the first transfer
The feeding position of the sheet material of the feeding means 4 and the setting of the first fixing device 5
Landing position, transfer position of second image forming unit 6, second transporter
The conveying position of the sheet material in the stage 7 and the fixing position of the second fixing device 8
The sheet material is arranged so that the
Are arranged in such a manner that the transport path is substantially straight. In addition to these configurations, it is desirable to arrange the sheet material of the sheet feeding unit 2 linearly including the entrance of the sheet material and the position where the sheet material of the stacking unit 9 is stacked . 1
Of the transport path.

In this example, the sheet feeding section 2 shows a sheet-sheet type configuration, and moves a sheet stacking table 11 on which a large number of sheets 10 are stacked in the direction of arrow A in an elevator manner as it is consumed by image formation. Thus, the top end of the sheet material is kept at a constant height. Further, a type in which roll paper is cut and used may be used, or a configuration in which a plurality of paper feed cassettes or paper feed decks are provided in the image forming apparatus, and different types are provided in the cassettes or on the upper surfaces of the decks, respectively. A type in which sheet materials of a size are stacked may be used.

The sheet material is fed in accordance with a command from a control unit based on an operator's command. For feeding the sheet material, a sheet feeding roller 12 is disposed so as to face the uppermost sheet material of the stacked sheet materials, and the sheet feeding roller 12 is driven to drive the uppermost sheet material of the sheet material. Is separated from the second and subsequent sheet materials and fed to the first image forming unit 3.

The sheet material fed by the paper feed roller 12 is conveyed to a registration roller pair 14 that has stopped rotating after passing through a conveyance roller pair 13, and the registration roller pair 14.
The registration roller pair 14 starts to rotate at the timing of the toner image on the rotating image carrier 15a of the first image forming unit, which will be described in the next order, and the first image formation is performed. It is sent to the transfer section 29 of the section 3. Alternatively, the conveying roller pair 13 and the registration roller pair 14 may be used together.

In the illustrated example, the first image forming section 3 has a configuration utilizing electrophotography, and has an image carrier such as a photosensitive drum or a photosensitive belt at the center thereof. A corona charger 16a or a charging roller for uniformly charging the surface of the image carrier 15a around the image carrier 15a, and the first document data read by a scanner or the like are projected by an LED or the like to project the image carrier. Optical projection device 1 for forming a latent image on 15a
7a, a developing device 18a for supplying a charged toner to the latent image to form a first toner image, and one surface of the sheet material sent from the paper feeding unit 2 (the lower surface in the figure) A transfer roller 19a for transferring the first toner image on the image carrier 15a, a cleaning device 20a for removing toner remaining on the surface of the image carrier 15a after the transfer, and a surface potential of the surface of the image carrier 15a. And an eraser lamp 21a for uniformly removing the charges, and these are arranged so as to sequentially act on the image carrier 15a, and an image is formed as is well known.

The first conveying means 4 conveys a sheet material having a first toner image formed on the lower surface thereof to a first fixing device 5 to be described later. Conveyor belt 22a composed of one wide endless belt extending in the entire width in the direction or a plurality of endless belts which are appropriately divided in the width direction of the sheet material and arranged in parallel.
And suction means 23a for sucking the sheet material to the conveying belt 22a and conveying the sheet material. A plurality of air inlet at a predetermined position of the peripheral surface of the conveyor belt 22a, enclosed in the conveyor belt 2 2a
Has a number of intake holes on the lower surface arranged in the space to be filled
An intake box and a suction means 23a such as a blower through a duct
To the inside of the conveyor belt 22a from these air inlets.
And suck the air to transfer the sheet material to the peripheral surface of the conveyor belt 22a.
It is transported in close contact. In particular, the sheet material is used for the first image forming.
Due to the weight of the sheet material when passing through the transfer section 29 of the section 3
Moving downward along the surface of the image carrier
Therefore, the first transport means is provided near the transfer section 29.
Preferably, the sheet material passes through the transfer roller 19a.
The sheet material is conveyed while being sucked immediately after passing. Take
Peeling of sheet material from image carrier 15a and subsequent conveyance
Is performed sufficiently and effectively, for example, the transfer unit 29
The peeling nail is placed at the position immediately after exiting from the image carrier 15a.
Does not damage the surface of the image carrier 15a in close proximity to the surface
(Image carrier 15a is in contact with
When it has sufficient hardness, such as a facsimile silicon photoreceptor
Etc.), and the leading edge of the sheet material that slips out of the transfer unit 29
Is effectively guided to the transport belt 22a. Also
Instead of the peeling claw, the sheet material and the image at the side edge of the sheet material
A release tape may be provided so as to be interposed between the carrier and the carrier.
No.

The role of the first conveying means 4 is important. As described above, the sheet material on which the unfixed toner image is placed on the lower surface can be transferred to the next portion without disturbing or destroying the toner image. Must be transported to Since the sheet material to be used will be different in size, for example,
When a small-sized sheet material is used, unnecessary and unnecessary suction is performed from the suction port (hole) of the belt portion (and the suction box) that is not covered with the sheet material, and sufficient suction of the sheet material is sufficiently performed. Can not hope. Therefore, depending on the size (width) of the sheet material for which the suction width of the suction box is to be suctioned, between the lower surface of the suction box and the conveyor belt 22a from the (both) end sides of the suction box toward the center side as appropriate. A movable (a pair of) shielding plates may be provided to change the position in the width direction.
In such a case, when the size of the sheet material is set in advance, or when the size is detected in the conveyance path fed to the first image forming unit 3, the shielding plate is moved to the optimum position according to the sheet material size. Move automatically. At this time, the suction means 23a sucks heat generated from the first fixing device 5 and discharges the heat out of the device . The discharge of such heat is
It is also important for protection.

The sheet material on which the first toner image is formed on the lower surface is then sent to the first fixing device 5. In the illustrated example, the first fixing device is a heating roller 2 pressed against each other.
The first toner image is heated and fixed to the sheet material by passing the sheet material between these rollers, which is a so-called heat fixing roller device including the pressure roller 4a and the pressure roller 25a.

The temperature of the first fixing device 5 is set at least.
Also, the fixing temperature is set low enough not to scatter the first toner image. The fixing temperature is controlled by the second image forming unit 6.
Also, the setting is made to such an extent that these peripheral devices are not contaminated even after passing through the second conveying means 7 and the first toner image is not disturbed. The first toner image is applied to a heating roller 24b and a pressure roller 2 of a second fixing device 8 described later.
5b and is fixed.

The second image forming section 6 has the same structure as the first image forming section 3, that is, a corona charger for uniformly charging the surface of the image carrier 15b around the image carrier 15b. 16b or a charging roller, and an optical projection device 17b for projecting the second document data read by a scanner or the like with an LED or the like to form a latent image on the image carrier 1;
A developing device 18b for supplying a charged toner to the latent image to form a second toner image and the other surface (upper surface as viewed in the drawing) of the sheet material sent from the first fixing device 5 A transfer roller 19b for transferring the second toner image on the image carrier 15b, a cleaning device 20b for removing toner remaining on the surface of the image carrier 15b after the transfer, and a surface potential of the surface of the image carrier 15b. And an eraser lamp 21b for uniformly removing charges, which are arranged so as to sequentially act on the image carrier 15b, and perform image formation as is well known.

The second conveying means 7 has the same structure as the first conveying means 4, and conveys a sheet material having a second toner image formed on the upper surface thereof to the second fixing device 8. . For example, a conveying belt 22b and a suction unit 2 that acts to convey the sheet material in close contact with the conveying belt 22b and convey the sheet material.
3b. A plurality of suction ports are provided at predetermined positions on the peripheral surface of the conveyor belt 22b, and suction means 23b such as a blower is provided.
Then, air is sucked from these intake ports toward the inside of the conveyor belt 22b, and the sheet material is adsorbed on the peripheral surface of the conveyor belt 22b and conveyed.

The second fixing device 8 has the same configuration as the first fixing device 5. In the illustrated example, the second fixing device comprises a heating roller 24b and a pressure roller 25b which are in pressure contact with each other.
A second toner image is heat-fixed to the sheet material by passing the sheet material between the rollers, and the first fixing device 5 fixes the first toner image to at least an extent not to be scattered. The toner image is heated and fixed again, and is discharged out of the apparatus.

The first and second images to be reproduced in the first image forming section 3 and the second image forming section 6 may be based on image information previously stored in storage means such as a computer. Alternatively, each original may be read by image reading means such as an image scanner or an OCR, and based on the read data.

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 3 and the second image forming section 6 by a control section via appropriate storage means or directly.

Normally, the image data of the odd-numbered document is sent to the optical projection device 17a for output, and the even-numbered image data is sent to the optical projection device 17b.

In this example, the sheet material stacking section 9 stacks the sheet materials discharged after the completion of image formation in an orderly manner. For example, the stacking section 9 is capable of vertically moving the continuously discharged sheet materials. The stacking table 26 is moved to the direction indicated by the arrow B so that the height of the stacked sheets is constant. At the time of image formation, the stacking platform 11 of the sheet feeding unit 2 and the stacking platform 26 of the stacking unit 9 are interlocked, and one of the stacking platforms is moved and used based on a signal obtained by adjusting one of the heights. . Reference numeral 30 denotes an abutting member that abuts the leading edge of the sheet material during ejection to align the leading edge of the sheet material.

Further, the image forming apparatus 1 includes a first unit 27 including a first image forming unit 3, a first transporting unit 4, and a first fixing device 5, a second image forming unit 6, A second unit 28 including the second transport unit 7 and the second fixing device 8
And a first unit 27 and a second unit 28
And are provided in a separable manner, and can be treated as separate bodies. Thus, when two-sided copying is desired, the first unit 27 and the second unit 28 are used in combination.

On the other hand, a first conveying path which is switchably provided with a first conveying path for discharging the sheet material passing through the first fixing device 5 to a tray outside or inside the apparatus without sending the sheet material to the second image forming section 6. Switching means 3 for switching between two transport paths according to two transport paths 33 and one side or both sides of a copier or a print machine.
And 4. In the illustrated example, the switching unit is located behind the first fixing device 5, and a known method can be applied. For example, the tip of the substantially triangular switching unit is rotated by a predetermined angle and the conveyance path is rotated. Has changed. Second transport path 33
Extends upward with respect to the first transport path, and continues to a tray 34 provided on an upper portion of the apparatus main body for loading sheet materials. The switching means switches via the operation panel in accordance with an operator's instruction when performing only one side of copying or printing. Alternatively, the switching control means (not shown)
If a trouble such as a paper jam occurs in the image forming section of
A sensor provided on the first transport path detects an abnormality and switches from the first transport path to the second transport path.

The operation of the above configuration will be described. The sheet material is fed from the sheet feeding unit 2 in accordance with an instruction from a control unit (not shown) based on an operator's instruction, and the registration roller pair 14 rotates with the timing of the first toner image in the first image forming unit 3. And sheet material first
Is conveyed to the image forming unit 3. In the first image forming unit 3, the first toner image formed on the image carrier 15a by a known image forming method is transferred to the lower surface of the sheet material via the transfer roller 19a. Next, the upper surface of the sheet material on which the first toner image is formed is conveyed to the first fixing device 5 while being conveyed by the conveyer belt 22a serving as the first conveyer unit 4 by the suction unit 23a.

The sheet material is fixed by the first fixing device 5 at a fixing temperature at which the first toner image does not scatter, and is conveyed from the first unit 27 to the second unit 28. In the second image forming section 6, the second toner image formed on the image carrier is transferred onto the upper surface of the sheet material by a known image forming method at a timing at which the sheet material is conveyed. Next, the surface of the sheet material on which the first toner image has been formed is conveyed to the second fixing device 8 while being conveyed by the conveyance belt 22b as the second conveyance means 7 by suction means 23b.

In the second fixing device 8, the second toner image formed on the other surface of the sheet material and the first toner image which has not been sufficiently fixed and passed through the first fixing device 5 are fixed. And is discharged toward the stacking unit 9 provided outside the second unit 28.

On the other hand, when only one side of copying or printing is performed, switching is performed so that the sheet material is guided from the first conveyance path to the second conveyance path by an instruction from a control panel or the like by the operator, or the second image is formed. When a trouble such as a paper jam occurs in the forming unit, a sensor (not shown) detects an abnormality and switches from the first conveyance path to the second conveyance path. The sheet material is conveyed along the second conveyance path, and is discharged to a tray 34 provided at an upper portion of the apparatus main body.

FIG. 2 shows another embodiment. FIG. 2 illustrates a configuration including an intermediate transfer roller in the configuration of the first and second image forming units illustrated in FIG. 1. In the illustrated example, the intermediate transfer roller 31a that presses the image carrier 15a to move the first toner image on the image carrier 15a, and the image carrier 1
An intermediate transfer roller 31b that moves the second toner image on the image carrier 15b by pressing the intermediate transfer roller 31b is provided.

The intermediate transfer roller 30a is connected to the image carrier 15a
And preferably has substantially the same diameter as the diameter of the transfer roller 19a. The transfer sheet material includes an intermediate transfer roller 30a and a transfer roller 19a set at an appropriate pressing force.
To transfer the first toner image on the intermediate transfer roller 30a.

The intermediate transfer roller is, for example, an adhesive sheet.
The image carrier 15 is composed of a rubber roller such as a recon.
a, the toner image formed on
And then reverse the toner from a power source (not shown).
By the action of the transfer roller to which a predetermined voltage of polarity is applied
The sheet material passing between them is formed on the intermediate transfer roller.
The first toner image formed is electrostatically attracted and transferred.
doing. The intermediate transfer roller 30a is thereafter moved to the intermediate transfer roller 30a.
Cleaning means (not shown) in contact with the surface of the roller 30a.
More toner remaining on the intermediate transfer roller is removed, and the next
Prepared for image transfer.

In addition to the adhesive intermediate transfer roller as described above, for example, the intermediate transfer roller is a roller having an insulating surface, and the roller is pre-charged to a polarity opposite to that of the toner by a corona discharger and charged. Then, the toner image on the image carrier is transferred to the intermediate transfer roller by electrostatic attraction.
Next, use an AC corona discharger or the like to
And neutralize the toner adhering to it, or
Forcibly reverse the polarity so that the toner has the opposite polarity.
Transfer with a polarity opposite to this inverted toner polarity
Roller transfers the toner image onto the sheet material
You may do it. The toner remaining on the transfer roller after transfer is
It is cleaned by a cleaning blade or the like. Smell above
Has been described as an intermediate transfer `` roller ''.
It may be a belt supported by a rubber. This place
If at least one roller supporting the belt has a small diameter
Then, the small-diameter roller faces the transfer roller 19a.
And thereby facilitate the peeling of the sheet material as described above.
Sex can be obtained. In addition, such a belt body
Even, it has the same properties as the above-mentioned intermediate transfer "roller"
Materials and peripheral devices can be applied.

Even if the leading edge of the sheet material passes through the sheet material, the diameter of both rollers is small, so that the sheet material is separated from the intermediate transfer roller 30a without being caught by the intermediate transfer roller 30a or the transfer roller 19a, and the first conveyance is performed. Carried by the means 4. The intermediate transfer roller 30b is formed of
This is the same as the description of the inter-transfer roller 30a.

In FIG. 2, the sheet material that has passed through the first first fixing device 5 is not sent to the second image forming unit 6 with respect to a first conveying path that is linearly provided. It has a second transport path switchably provided with a first transport path for discharging to a tray inside the apparatus, and switching means 32 for switching between two transport paths according to one side or both sides of a copier or print. . In the illustrated example, a switching unit 32 that switches the transport path from the first transport path behind the first fixing device 5;
A second conveyance path 33 extending downward with respect to the first conveyance path and extending toward the second unit 28; and a tray 3 provided in the second unit 28 for accumulating sheet materials.
And 4. The sheet materials accumulated on the tray 34 can be obtained by, for example, being provided so as to be able to be pulled out to the near side as viewed in the drawing.

The switching means 32 switches via the operation panel in accordance with an operator's instruction when performing only one side of copying or printing. Alternatively, when a trouble such as a paper jam occurs in the second image forming unit as a switching control unit, this state is detected by a sensor (not shown) and the first conveyance path is switched to the second conveyance path.

In the above description, the first toner image is formed on the lower surface of the sheet material and the second toner image is formed on the upper surface of the sheet material. The image may be formed on the upper surface of the sheet material, and then the second toner image may be formed on the lower surface of the sheet material by the second image forming unit 6. FIG. 1 is an example of the arrangement of the components, and the size of each component is not limited.

[0047]

As described above, when only one side of copying or printing is performed, switching can be performed according to the instruction of the operator. Alternatively, when a trouble such as a paper jam occurs in the second image forming unit as a switching control unit, a sensor (not shown) detects this state and switches from the first conveyance path to the second conveyance path. With the configuration in which the sheet material is transported along the second transport path and accumulated on the tray,
An easy-to-use image forming apparatus can be provided. In particular, even if a trouble occurs in the second image forming unit, the next sheet material is not adversely affected. Further, since the sheet material is conveyed almost linearly in the image forming apparatus, the sheet material can be conveyed without imposing a stiff posture. Can be as fast as possible.

[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 sectional view showing another example of the image forming apparatus according to the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper feed unit 3 First image forming unit 4 First transport unit 5 First fixing device 6 Second image forming unit 7 Second transport unit 8 Second fixing Apparatus 9 Stacking unit 10 Sheet material 11 Stacking table 12 Paper feed roller 13 Transport roller pair 14 Registration roller pair 15a, b Image carrier 16a, b Corona charger 17a, b Optical projection device 18a, b Developing device 19a, b Transfer roller 20a, b Cleaning device 21a, b Eraser lamp 22a, b Conveyor belt 23a, b Suction means 24a, b Heat roller 25a, b Pressure roller 26 Stacking table 27 First unit 28 Second unit 29 Transfer unit 30 Member 31a, b Intermediate transfer roller 32 Switching means 33 Second transport path 34 Tray

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

Claims (6)

[Claims] A first conveying path for a sheet material is provided in a substantially horizontal direction from an input port to an output port of the sheet material, and a first toner image is formed along one of the first conveying paths on one side of the sheet material. A first image forming unit for forming the first toner image, a first conveying unit for supporting and conveying a surface of the sheet material opposite to the surface on which the first toner image is formed, and the first conveying unit; A first fixing device that fixes a toner image, a second image forming unit that forms a second toner image on the other surface of the sheet material, and a sheet on which the first toner image is formed A second conveying unit that receives and conveys the surface of the material, and a second fixing device that fixes the second toner image, are sequentially arranged, and further, the sheet material that has passed through the first fixing device is transferred to the second fixing unit. The first transporting unit that discharges the sheet to a tray outside or inside the apparatus without sending the sheet to the second image forming unit; An image forming apparatus comprising: a second transport path provided to be switchable with a transport path; and a switching unit configured to switch between the two transport paths according to one side or both sides of a copying machine or print. 2. The image forming apparatus according to claim 1, wherein each of the first image forming unit and the second image forming unit includes an image carrier that forms a toner image and a transfer roller that faces the first image forming unit through the first conveyance path. The image forming apparatus according to claim 1, wherein: 3. The image forming section according to claim 1, wherein the first image forming section and the second image forming section each include an image carrier for forming a toner image, and a toner image which is in contact with the image carrier to form a toner image. The image forming apparatus according to claim 1, further comprising: an intermediate transfer roller that conveys the sheet to a surface; and a transfer roller that faces the intermediate transfer roller via the first transport path. 4. The apparatus according to claim 1, wherein the second transport path extends upward with respect to the first transport path, and discharges the sheet material to an upper portion of the apparatus main body. Image forming apparatus. 5. When a jam occurs in any of the second image forming section, the second conveying means, and the second fixing device, a sheet material conveyed next is second conveyed. 5. The image forming apparatus according to claim 1, further comprising a switching control unit that switches to a path and discharges the sheet to a tray outside or inside the apparatus. 6. An image forming apparatus comprising: a first unit including a first image forming unit, a first conveying unit, and a first fixing device; a second image forming unit; and a second conveying unit. And a second unit including a second fixing device, wherein the first unit and the second unit are provided so as to be separable, and the second conveyance unit is provided in the second unit. A road and said tray are provided.
The image forming apparatus according to any one of the above.