JP2002214974A - Image forming device and image formation system provided with the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an image forming speed faster in an image forming device which forms images on both faces of a recording medium by transferring image formed on a first image carrier on an intermediate transferring body and by transferring the image on the intermediate transferring body on the face of one side of the recording medium and also by transferring image formed next on the first image carrier on the face of the other side of the recording medium. SOLUTION: In this image forming device a second image carrier 2 different from a first image carrier body 2A is made attachable and a first image on the second image carrier 2 is transferred on an intermediate transferring body 3 and the image is transferred on the face of one side of a recording medium P and, moreover, a second image formed on the first image carrier 2A is transferred on the face of the other side of the same recording medium P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus capable of forming an image on one surface and the other surface of a recording medium, respectively, and an image forming system provided with the image forming device.

[0002]

2. Description of the Related Art Electronic copiers, printers, facsimile machines,
An image forming apparatus of the above type configured as a printing machine or a multifunction machine having at least two of these functions has been conventionally known. Generally, this type of conventional image forming apparatus transfers a first image formed on an image carrier to one surface of a recording medium, fixes the transferred image, reverses the recording medium, and again An image is formed on both sides of the recording medium by feeding the image onto the image carrier, transferring the second image formed on the image carrier to the other surface of the recording medium, and fixing the second image. Is configured. However, according to the image forming apparatus of this method, it is necessary to feed the recording medium twice to the image carrier, so that it takes a long time to form an image on both sides of the recording medium, and the productivity is reduced. You can't escape the drawbacks.

Therefore, the image formed on the image carrier is transferred to an intermediate transfer member, the transferred image is transferred to one surface of a recording medium, and the image formed next on the image carrier is transferred to the intermediate transfer member. An image forming apparatus has been proposed in which an image is formed on both sides of a recording medium by directly transferring the image to the other side of the same recording medium without using an intermediate transfer member (for example, Japanese Patent Application Laid-Open No. Hei 1-209470). reference). According to this type of image forming apparatus, an image can be formed on both sides of the image carrier only once by sending the recording medium to the image carrier, so that the productivity of a two-sided image can be improved. However, also in this image forming apparatus, the image transferred on the intermediate transfer body is
After the start of the transfer of the first image formed on the image carrier to the intermediate transfer body, so that the next image formed on the image carrier can be transferred to one surface and the other surface of the same recording medium, respectively.
Since the intermediate transfer body is rotated once, and then the image formed on the image carrier is started to be transferred to the recording medium, it takes a considerably long time to finish transferring the image to both sides of the recording medium. And the productivity of double-sided images has not been sufficiently improved. This type of image forming apparatus is referred to as a first conventional image forming apparatus.

On the other hand, the first and second image carriers are brought into contact with the intermediate transfer member, an image formed on the second image carrier is transferred to the intermediate transfer member, and the transferred image is recorded on a recording medium. An image forming apparatus has been proposed which transfers an image formed on a first image carrier to the other surface of the same recording medium and forms an image on both sides of the recording medium while transferring the image to one surface of the recording medium. See JP-A-9-269616). This type of image forming apparatus is referred to as a second conventional image forming apparatus. According to the second conventional image forming apparatus, it is possible to produce a two-sided image more than the first conventional image forming apparatus described above. The image forming properties can be further improved, and an image can be formed on each surface of the recording medium in a short time. However, this second conventional image forming apparatus is
It is necessary to provide a plurality of image carriers for the purpose of forming images on both sides of the recording medium.

[0005]

There are various demands for a user for an image forming apparatus, and it is desired to obtain an image forming apparatus capable of obtaining a double-sided image at a high speed even if the product price is somewhat high. Some users think that it is preferable to lower the product price if a two-sided image can be obtained, even if the image forming speed is somewhat slow. The former user obtains the second conventional image forming apparatus, and the latter user uses the first conventional image forming apparatus, but starts using the first conventional image forming apparatus. In some cases, the user later needs an image forming apparatus that can form images on both sides of the recording medium at a higher speed.
In such a case, the user has to obtain the second conventional image forming apparatus again, which imposes a great economic burden on the user.

A first object of the present invention is to provide an image forming apparatus capable of forming a double-sided image which can eliminate the above-mentioned conventional problems.

A second object of the present invention is to provide an image forming system provided with an image forming apparatus capable of forming a double-sided image, which can eliminate the above-mentioned conventional problems.

[0008]

In order to achieve the first object, the present invention provides an image carrier on which an image is formed, and an intermediate transfer member on which the image formed on the image carrier is transferred. The image transferred to the intermediate transfer body is transferred to one surface of a recording medium, and the image formed next on the image carrier is transferred to the other surface of the recording medium to form a recorded image. In the obtained image forming apparatus, the image carrier is a first image carrier,
When the image forming mode is the first mode, an image carrier mounting portion for mounting a second image carrier different from the first image carrier to the image forming apparatus main body is provided. When the second image carrier is mounted, the image formed on the second image carrier is transferred to the intermediate transfer member, and the transferred image is transferred to one surface of a recording medium. An image forming apparatus, wherein an image formed on a first image carrier is transferred to the other surface of the recording medium to form an image in a second mode for obtaining a recorded image. We propose (Claim 1).

At this time, when the second image carrier is mounted on the image forming apparatus main body, it is advantageous to provide a mode switching means for automatically switching the image forming mode to the second mode by the mounting. (Claim 2).

[0010] In the image forming apparatus according to the first or second aspect, it is advantageous that a third mode in which only an image formed on the first image carrier is transferred to a recording medium can be selected. (Claim 3).

Further, in the image forming apparatus according to the third aspect, the second image carrier is mounted on the main body of the image forming apparatus to perform an image forming operation, whereby the second image carrier is formed.
It is advantageous that the third mode is selected when the toner for forming an image on the image carrier runs out.

Further, in the image forming apparatus according to any one of claims 1 to 4, an image formed on the second image carrier is transferred to an intermediate transfer member, and only the image is transferred to a recording medium. It is advantageous to configure the fourth mode to be selectable (claim 5).

Further, in the image forming apparatus according to the fifth aspect, when the toner for forming an image on the first image carrier runs out, the fourth mode is selected. It is advantageous (claim 6).

In the image forming apparatus according to any one of claims 1 to 6, it is advantageous that the first mode can be selected even when the second image carrier is mounted. Claim 7).

Further, in the image forming apparatus according to the present invention, it is advantageous that the first mode can be selected when the toner for forming an image on the second image carrier runs out. (Claim 8).

Further, in the image forming apparatus according to any one of claims 1 to 8, the first image carrier and the second
It is advantageous that the image bearing members are formed in substantially the same shape and substantially the same size (claim 9).

Further, in the image forming apparatus according to any one of claims 1 to 9, the first image carrier,
At least one image forming member for forming an image on the first image carrier;
Two image forming means are configured as a first image forming unit,
The second image carrier and at least one image forming unit for forming an image on the second image carrier are configured as a second image forming unit, and the first and second image forming units are formed as a second image forming unit. The image forming unit is configured to be attached to and detached from the image forming apparatus main body from the same surface side, and the second image forming unit is configured to be mounted on the image carrier mounting portion. (Claim 10).

Further, in the image forming apparatus according to the tenth aspect, the first and second image forming units are configured to be attached to and detached from a main operation surface of the image forming apparatus main body. It is advantageous (claim 11).

Further, in the image forming apparatus according to any one of claims 1 to 11, the first image carrier and at least one image forming device for forming an image on the first image carrier. Means is configured as a first image forming unit, wherein the second image carrier and at least one image forming means for forming an image on the second image carrier are included in a second image forming unit. And a first image forming unit and a second image forming unit.
So that one of the image forming units can be mounted also at the mounting position of the other image forming unit.
It is advantageous that the image forming unit and the second image forming unit are configured (claim 12).

In the image forming apparatus according to the twelfth aspect, the first image forming unit and the second image forming unit are configured to have substantially the same size and substantially the same shape. It is advantageous (claim 13).

Further, in the image forming apparatus according to any one of claims 1 to 13, after the image on the intermediate transfer body is transferred to a recording medium, transfer residual toner attached to the intermediate transfer body is removed. A cleaning device for an intermediate transfer member having a cleaning member, wherein the cleaning member is always in contact with the intermediate transfer member when the second image carrier is mounted on the image forming apparatus main body. It is advantageous (claim 14).

The image forming apparatus according to any one of claims 1 to 14, wherein the image transferred from the second image carrier to an intermediate transfer member and the image formed on the first image carrier. It is advantageous to have transfer means for simultaneously transferring the data to one surface and the other surface of the recording medium, respectively.

Further, in the image forming apparatus according to the present invention, the transfer means may include an image on the intermediate transfer member charged to the first polarity and a second polarity opposite to the first polarity. It is advantageous that the image on the charged first image carrier is transferred to one surface and the other surface of the recording medium, respectively.

In the image forming apparatus according to the present invention, an image charged to the second polarity is formed on each of the first and second image carriers and transferred to an intermediate transfer member. It is advantageous to provide a polarity conversion unit for converting the charged polarity of the image into the first polarity.

Further, in the image forming apparatus according to any one of claims 1 to 17, a fixing device arranged to fix an image transferred to a recording medium superimposed on the intermediate transfer body is provided. It is advantageous to have it (claim 18).

20. The image forming apparatus according to claim 18, wherein the fixing device has a fixing member for fixing an image by contacting a recording medium superimposed on the intermediate transfer member, and wherein the second image is fixed. Advantageously, when the carrier is mounted on the image forming apparatus main body, the fixing member is always in direct contact with the intermediate transfer body or via a recording medium (claim 19).

The image forming apparatus according to claim 18 or 19, wherein the fixing device is configured to fix the image on the recording medium at least by the action of heat, and Cooling means is provided for cooling an intermediate transfer body portion downstream of the fixing position where the fixing is performed and upstream of the transfer position where an image is transferred from the second image carrier to the intermediate transfer body. (Claim 20).

Further, in the image forming apparatus according to any one of claims 1 to 20, an indication that the second image carrier is attached to the image forming apparatus main body may be displayed.
It is advantageous that the image is displayed on at least one of a display unit of the image forming apparatus itself and a host device connected to the image forming apparatus (claim 21).

Further, in order to achieve the second object, the present invention proposes an image forming system in which the image forming apparatus according to any one of claims 1 to 21 and a host device are connected. Item 22).

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic vertical sectional view of the image forming apparatus of this embodiment, and the image forming apparatus shown here is configured as a printer. In the main body 1 of the image forming apparatus, there are provided an image carrier 2A configured as a drum-shaped photoreceptor and an intermediate transfer member 3. A part of the peripheral surface of the image carrier 2A is Is in contact with The intermediate transfer member 3 illustrated here is an endless belt that is wound around a plurality of rollers 4 and 5 and is driven to travel in the direction of arrow A. However, a drum-shaped intermediate transfer member that is rotationally driven is used. Can also.
Similarly, an endless belt that is wound around a plurality of rollers and driven to travel can be used as the image carrier 2A. This corresponds to a second image carrier 2 described later (see FIG. 2).
The same applies to the case of. In the example shown in the figure, the image forming apparatus main body 1 forms a housing of the image forming apparatus.

Around the image carrier 2A, there are arranged respective image forming means of a static eliminator 6A composed of a static elimination lamp, a charging device 7A, a developing device 8A and a cleaning device 9A. The body 2A is integrally assembled to a unit case 10A (see FIGS. 5 and 9) not shown in FIG. 1 to form an image forming unit 11A. The image carrier 2A is rotatably supported by the unit case 10A. This image forming unit 11A
As described below, along the guide stay 52A fixed to the image forming apparatus main body 1, the image forming apparatus is supported so that it can be pulled out toward the near side of the image forming apparatus main body.

An exposing device 12A is arranged near the image carrier 2A. In the illustrated example, the exposing device 12A does not constitute an element of the image forming unit 11A. It is configured as a separate element from the image forming unit 11A.

A fixing device 20 is disposed at a position downstream of the image carrier 2A in the direction of movement of the surface of the intermediate transfer member.
The fixing device 20 shown here includes a case 21 detachably supported by the image forming apparatus main body 1, a fixing roller 22 rotatably supported by the case 21 and driven to rotate in the direction of arrow E, and an inner portion thereof. And a heater 23 provided for the When the heater 23 is energized, the heater 23
Generates heat, whereby the fixing roller 22 is maintained at a temperature suitable for fixing the image transferred to the recording medium, and the image transferred to the recording medium can be fixed as described later. The fixing roller 22 constitutes an example of a fixing member that fixes an image transferred to a recording medium by at least the action of heat on a surface of the recording medium, and a fixing member other than the fixing roller, for example, a plurality of rollers. It is also possible to use a fixing belt stretched over the belt.

Further, in the image forming apparatus of this embodiment, a heating means 24 is provided inside the intermediate transfer member 3 so as to face the fixing roller 22. The heating means 24 shown as an example in the figure is constituted by a heating roller 49 rotatably supported and abutting on the back surface of the intermediate transfer member 3 and a heater 50 disposed inside the heating roller 49. Is heated.

A cleaning device 29 for the intermediate transfer member 3 is provided further downstream than the fixing device 20 in the direction of movement of the surface of the intermediate transfer member. The cleaning device 29 illustrated here includes a cleaning roller 30 which is an example of a cleaning member that rotates and abuts on the surface of the intermediate transfer member to remove transfer residual toner attached to the surface of the intermediate transfer member. A blade 31 for scraping and removing the removed toner, a cleaning case 32 for supporting the toner, and a toner conveying device 32a for conveying the toner removed by the blade 31 to the outside of the cleaning case 32. Any type of cleaning device may be used. The toner transported outside the cleaning case is collected in a toner storage unit (not shown).

At a position further downstream than the cleaning device 29 in the direction of movement of the intermediate transfer member surface, the intermediate transfer member 3
Is provided with a cooling means 33 for cooling the air. As a cooling unit, a blower that blows cool air onto the intermediate transfer body can be adopted, but in the illustrated example, a plurality of heat pipes 34 that contact the front and back surfaces of the intermediate transfer body and take heat from the intermediate transfer body are used. Cooling means 33 is configured.

The image forming apparatus main body 1 is provided with a fan 35. The fan 35 discharges the air inside the image forming apparatus main body to the outside and prevents the temperature inside the image forming apparatus main body from excessively rising. You. Reference numerals 36 and 36a in FIG. 1 denote electrical equipment and a control device provided in the image forming apparatus main body 1.

Next, an operation example of forming an image on both sides of a recording medium by the above-described image forming apparatus will be described. During this image forming operation, the intermediate transfer member 3 is driven to rotate in the direction of arrow A, and the image carrier 2A is driven to rotate in the direction indicated by arrow B1. At this time, the surface of the image carrier 2A is
Then, the surface is uniformly charged to a predetermined polarity by the charging device 7A, that is, a negative polarity in the example of FIG. The charged surface is selectively irradiated with light corresponding to the write information from the exposure device 12A, and the image carrier 2A
An electrostatic latent image corresponding to the information is formed on the surface of the. In this example, the image carrier portion irradiated with light from the exposure device 12A and having a reduced absolute value of the surface potential becomes an electrostatic latent image, that is, an image portion. This electrostatic latent image is visualized as a toner image by the developing device 8A, and an image with toner is formed on the image carrier 2A.

The developing device 8A shown here uses the developer DA
And a developing roller 72A that carries and transports the developer DA. Developer D
As A, for example, a two-component developer formed by mixing a powdery toner and a carrier, a one-component developer containing no carrier, or the like can be used. In either case,
The toner stored in the developing case 71A has a predetermined polarity,
In the illustrated example, the image carrier 2A is charged to the same negative polarity as the charged polarity, and the toner electrostatically transfers to the electrostatic latent image formed on the image carrier 2A, and the electrostatic latent image is Visualized. As described above, in this example, the electrostatic latent image is visualized by the reversal development, but the electrostatic latent image may be developed by the regular development method.

Assuming that the image formed on the image carrier 2A as described above is the first image, the first image is transferred to the image carrier by the transfer means 13A disposed on the back side of the intermediate transfer body 3. It is electrostatically transferred to the surface of the intermediate transfer body 3 that moves in synchronization with the body 2A. A positive transfer voltage having a polarity opposite to the charging polarity of the toner on the image carrier 2A is applied to the transfer unit 13A, whereby the image on the image carrier 2A is electrostatically transferred onto the intermediate transfer body 3. Is done. The toner remaining on the surface of the image carrier 2A after the image transfer is removed by the cleaning device 9A, and the surface of the image carrier 2A after cleaning is irradiated with light from the static eliminator 6A to initialize the surface potential, Prepare for the next imaging cycle.

The intermediate transfer member 3 carries a first image made of toner on its surface and moves in the direction of arrow A. When this image passes through the portions of the fixing device 20 and the heating means 24,
The fixing device 20 and the heating means 24 are in a non-operating state. For example, the power supply to the heaters 23 and 50 is turned off, or the on / off of the heaters 23 and 50 is controlled, so that the fixing roller 22 and the heating roller 49 are maintained at a temperature lower than a temperature suitable for fixing an image. 22 and the heating roller 49 are separated from the intermediate transfer body 3. The heaters 23 and 50 may be set at a low temperature as described above, and at least the fixing roller 22 may be separated from the surface of the intermediate transfer body 3. This prevents the image transferred from the image carrier 2 </ b> A to the intermediate transfer member 3 from being fixed on the intermediate transfer member 3 and being prevented from being disturbed by the fixing roller 22.

The unfixed image on the intermediate transfer body 3 that has passed through the portion of the fixing device 20 further passes through the cleaning roller 30 of the cleaning device 29 and the heat pipe 34 in this order. ,
The heat pipe 34 located on the surface side of the intermediate transfer body 3
It is separated from the surface of the intermediate transfer member 3. This prevents the unfixed first image on the intermediate transfer member from being disturbed.

At an appropriate time after the rear end of the first image on the intermediate transfer member 3 has passed the cleaning roller 30, the cleaning roller 30 comes into contact with the surface of the intermediate transfer member 3. The heat pipe 34 abuts on the surface of the intermediate transfer member 3 at an appropriate time after the rear end of the first image on the third transfer member 3 has passed the portion of the heat pipe 34.

The first image on the intermediate transfer member 3 subsequently passes through a charger 14 which is an example of a polarity conversion means arranged at a distance from the intermediate transfer member 3. At this time,
Due to the discharging action of the charger 14, the charging polarity of the first image carried on the surface of the intermediate transfer member 3 is reversed. In this example, the toner constituting the first image is charged by the charger 14 and its polarity is inverted to positive.

On the other hand, the next image composed of toner is formed on the image carrier 2A by charging, exposing, and developing in the same manner as described above. If this image is referred to as a second image as necessary, the leading end of the first image transferred onto the intermediate transfer member 3 is moved more than the image carrier 2A with the movement of the surface of the intermediate transfer member. When a predetermined position is reached, a next image writing operation to the image carrier 2A is started. The toner constituting the second image formed on the image carrier 2A is also charged to the same polarity as the first image formed on the image carrier 2A, that is, the negative polarity.

A sheet feeding device 1 is provided at a lower portion of the image forming apparatus main body 1.
The paper feeding device 15 includes a paper feeding cassette 16 for storing a recording medium P made of, for example, sheet-shaped transfer paper or a resin sheet, and a paper feeding roller 17. Is rotated in the direction of arrow C while contacting the upper surface of the uppermost recording medium, whereby the uppermost recording medium P is sent out in the direction of arrow DP.

The sent recording medium P is rotated at a predetermined timing by the rotation of the registration roller pair 18 so that the intermediate transfer member 3
Is transferred to a transfer position between the image carrier 2A and the image carrier 2A. Also at this time, a transfer voltage having a polarity opposite to the charge polarity of the second image formed on the image carrier is applied to the transfer unit 13A. Thereby, the first image carried on the surface of the intermediate transfer member 3 is electrostatically transferred to one surface of the recording medium, that is, the recording medium surface that is in contact with the surface of the intermediate transfer member,
The next second image formed on the outer peripheral surface of the image carrier 2A is:
The image is electrostatically transferred to the other surface of the same recording medium, that is, the surface of the recording medium in contact with the outer peripheral surface of the image carrier 2A. By applying a positive charge to the transfer unit 13A, the positive polarity toner on the intermediate transfer body repels, the negative polarity toner on the surface of the image carrier is sucked, and the first and second images are transferred to each of the recording media P. Each is electrostatically transferred to the surface. The timing to start writing the next image onto the image carrier 2A and the timing to start feeding the recording medium P are adjusted so that the first and second images are correctly transferred to one surface and the other surface of the recording medium. Controlled.

The image forming apparatus shown in FIG. 1 is provided with a manual paper feeder 19, from which a recording medium is fed.
The first and second images can be transferred to the respective surfaces in the same manner as described above.

The toner remaining on the image carrier 2A without being transferred to the recording medium is removed by the cleaning device 9A of the image forming unit 11A, and the surface of the image carrier after the removal is subjected to a charge removing operation by the charge removing device 6A. This is no different from the previous image forming operation.

The recording medium on which the image has been transferred to each surface by the transfer means 13A passes between the intermediate transfer member 3 and the fixing roller 22 while being carried on the surface of the intermediate transfer member 3. At this time, the fixing roller 22 and the heating roller 49
The heaters 23 and 50 maintain a temperature suitable for fixing an image formed of toner on a recording medium, and the rollers 22 and 49 rotate while contacting the front and back surfaces of the intermediate transfer body 3 respectively. ing. Intermediate transfer member 3
The recording medium carried on the surface of the fixing roller 22
At this time, heat and pressure are applied to the first and second images respectively transferred to one surface and the other surface of the recording medium, whereby the toner constituting each image is melted and Is fixed on each side. Thus, a recorded image is obtained on each surface of the recording medium. The heating unit 24 applies heat to the recording medium from the back side of the intermediate transfer body 3, and the recording medium P is cooperated by the heating unit 24 and the fixing roller 22.
The first and second images transferred to the respective surfaces can be efficiently fixed. The heating unit 24 assists the fixing device 20. In this way, the first and second images transferred to each side of the recording medium P are simultaneously fixed to each side of the recording medium.

After the recording medium that has passed the fixing position is separated from the intermediate transfer member 3, while being guided by the guides 25 and 26, an arrow F is directed to a discharge stack 28 on the upper portion of the image forming apparatus main body by a pair of discharge rollers 27. Is discharged as indicated by.

On the other hand, untransferred toner remaining on the surface of the intermediate transfer member 3 without being transferred to the recording medium P is removed by the cleaning roller 30 in contact with the surface of the intermediate transfer member 3, and passes through the cleaning device 29. The transferred intermediate transfer member portion is connected to a heat pipe 34 in contact with the surface of the intermediate transfer member 3.
Cooling.

By repeatedly performing the above-described operation, a large number of recording media are stacked on the discharge stack unit 28 one above the other. When the paper discharge unit is configured as described above, the recording medium is placed on the paper discharge stack unit 28 with the other surface onto which the second image has been transferred from the image carrier 2A facing down. In order to align the page order of the images formed on a large number of recording media placed on the image carrier, first, the first image of the second page is formed on the image carrier 2A, and this image is Transfer to one surface of the recording medium, and the image carrier 2
A second image of the first page is formed on A, and this is transferred to the other surface of the recording medium. Similarly, the first image of the fourth page formed on the image carrier 2A is transferred to one surface of the next recording medium via the intermediate transfer member 3 on one surface of the next recording medium. The second image of the third page formed on the image carrier 2A is transferred to the other surface of the recording medium. By repeating such an operation, the page order of the images formed on each surface of the recording medium stacked on the discharge stack unit 28 can be aligned.

The first image formed on the surface of the image carrier 2A is a normal image. When this first image is transferred onto the intermediate transfer member 3, it becomes a reverse image, that is, a mirror image. Is transferred to one surface of the recording medium, so that the image becomes a normal image. The second image formed on the image carrier 2A is a reverse image, which is transferred to the other surface of the recording medium and becomes a normal image.

Each of the first and second image carriers 2A is placed on the image carrier 2A so that the page order of the image formed on the recording medium is aligned as described above.
In order to form a second image, a known method of storing image data in a memory is employed. Further, in order to form a normal image and a reverse image on the image carrier 2A, a known image carrier is used. Processing technology is adopted.

As described above, the image forming apparatus shown in FIG. 1 includes the image carrier 2A on which an image is formed and the intermediate transfer member 3 on which the image formed on the image carrier is transferred. ,
The image transferred to the intermediate transfer member 3 is transferred to one surface of a recording medium P, and the image formed next on the image carrier 2A is transferred to the other side of the same recording medium without the intermediate transfer member 3 interposed therebetween. And a recording image is obtained by transferring the image onto the surface. This image forming mode will be referred to as a first mode.

When the image forming operation is performed in the above-described first mode to form an image on both sides of the recording medium, the intermediate transfer member 3
And the image carrier 2A, it is only necessary to send the recording medium P once to the transfer position where an image is formed on each surface of the recording medium, so that the same recording medium is sent twice to the transfer position. The productivity of double-sided images can be increased. However, as described above, also in the first mode, after the transfer of the first image formed on the image carrier 2A to the intermediate transfer member 3 starts, the intermediate transfer member 3 makes one rotation. Thereafter, the second image formed on the image carrier 2A starts to be transferred to the recording medium P, so that the productivity of the two-sided image is not sufficiently improved.

Therefore, in the image forming apparatus of this embodiment,
As shown in FIG. 2, when the above-described image carrier 2A is a first image carrier, a second image carrier 2 different from the first image carrier 2A is attached to the image forming apparatus main body 1. An image carrier mounting portion for mounting is provided. The second image carrier 2 is mounted on an image forming apparatus of a user who desires to form an image on both sides of a recording medium at a higher speed. The second image carrier 2 is mounted on the image forming apparatus main body 1 in an optional format according to a user's request.

FIG. 2 shows a state in which the second image carrier 2 is mounted in the image forming apparatus main body 1. At this time, the first image carrier 2A and the second image carrier are used. 2 are located opposite to each other, and a part of the outer peripheral surface of the second image bearing member 2 is also in contact with the surface of the intermediate transfer member 3. Intermediate transfer member 3
Is disposed between the first image carrier 2A and the second image carrier 2 in a state of contact with the first image carrier 2A and the second image carrier 2.

The second image carrier 2 is located downstream of the cleaning device 29 and the cooling means 33 with respect to the moving direction of the surface of the intermediate transfer member 3, and transfers an image from the first image carrier to a recording medium. It is located upstream of the transfer position where the image is transferred, and is located at a position sandwiching the recording medium transport path with respect to the first image carrier 2A.

Further, the image forming means of the charge removing device 6, the charging device 7, the developing device 8 and the cleaning device 9 are also provided around the second image carrier 2 in the same manner as in the case of the first image carrier 2A. Are arranged respectively. This developing device 8 also has a developing case 71 containing a one-component or two-component developer D.
And a developing roller 72 that carries and transports the developer D. These image forming means and the second image carrier 2
However, the image forming unit 11 is configured integrally with a unit case 10 (see FIG. 9) not shown in FIG. 2, and the second image carrier 2 is rotatable with respect to the unit case 10. It is supported by. First image carrier 2A
The image forming unit 11A having the second image carrier 2 is referred to as a first image forming unit.
The first image forming unit 11A and the second image forming unit 11 have substantially the same configuration.

An exposure device 12 different from the second image forming unit 11 is also arranged near the second image carrier 2.

The second image forming unit 11 also includes a guide stay 52 fixed to the image forming apparatus main body 1 as described later.
Is set by being pushed into the back side of the image forming apparatus main body 1 along the line, and pulled out toward the front side of the image forming apparatus main body. By setting the second image forming unit 11 in the image forming apparatus main body 1 in this way, the second image carrier 2 is mounted on the image forming apparatus main body 1. As described above, the guide stay 52 constitutes an example of an image carrier mounting portion for mounting the second image carrier 2 to the image forming apparatus main body 1, but an image carrier mounting portion of another form is used. Can be appropriately adopted.

In the following description, if necessary, each image forming means for forming an image on the first image carrier 2A, and the element directly related to this means "first" language. Each of the image forming means for forming an image on the second image carrier 2 and these directly related elements will be referred to with the word "second".

The image forming apparatus according to the present embodiment includes a second image carrier 2
Is attached as shown in FIG.
It is configured so that image formation can be performed in the mode.

Also in this case, the intermediate transfer member 3 is driven to rotate in the direction of arrow A as shown in FIG. 2, and the first and second image carriers 2A and 2 rotate in the directions indicated by arrows B1 and B2, respectively. Driven. At this time, the first mode in the first mode is used.
An image is formed on the second image carrier 2 in exactly the same manner as when an image is formed on the image carrier 2A. That is, the second image carrier 2 is neutralized by the static eliminator 6, the surface of the second image carrier 2 is negatively charged by the second charger 7, and the charged surface of the second image carrier 2 is changed to the second exposure device. Exposure is performed by 12 to form an electrostatic latent image, and the electrostatic latent image is reverse-developed by a negative polarity toner of the developing device 8 to be visualized as a toner image. An image is formed on the second image carrier in this way, but this image will be referred to as a first image here.

The first image formed on the second image carrier 2 is transferred in the direction of arrow A by the second transfer means 13 disposed on the back side of the intermediate transfer member 3. 3
Is electrostatically transferred to the surface of the substrate. The transfer residual toner remaining on the second image carrier after the image transfer is removed by the second cleaning device 9, and the surface of the second image carrier 2 after the cleaning is neutralized by the second neutralization device 6. The operation is the same as when an image is formed on the first image carrier 2A in the first mode.

The second transfer means 13 is also provided in an image forming apparatus in which the second image carrier 2 is not mounted as shown in FIG. 1, and performs image formation in the first mode described above. Is performed, the transfer means 13 serves exclusively as a tension roller for the intermediate transfer body 3, and when image formation is performed in the second mode, the transfer means 13 is mounted on the The transfer unit 13 is connected to a power supply (not shown), and a positive-polarity transfer voltage is applied to the transfer unit 13.

When the first image carried on the surface of the intermediate transfer member 3 passes through the portion of the charger 14 with the movement of the surface of the intermediate transfer member 3, the charge polarity of the first image is reversed to a plus.

On the other hand, on the first image carrier 2A, charging, exposure, and exposure are performed by the first charging device 7A, the first exposing device 12A, and the first developing device 8A in the same manner as described above. By performing the development processing, an image composed of the toner of the negative polarity is formed. Here, this image is
Image.

The recording medium P is fed from the paper feeder 15 or 19 in exactly the same manner as described above, and is fed between the first image carrier 2A and the intermediate transfer body 3. Also at this time, a positive transfer voltage is applied to the first transfer means 13A, whereby the first image on the intermediate transfer body 3 is transferred to one surface of the recording medium, and the first image is transferred to the other surface. The second image on the image carrier is transferred. The timing to start writing the second image on the first image carrier 2A and the timing of the recording medium P so that the first and second images are correctly transferred to one surface and the other surface of the recording medium P, respectively. The feeding start timing is controlled.

The first image carrier 2 without being transferred to the recording medium
The transfer residual toner adhered to A is removed by the first cleaning device 9A, and the surface of the image carrier after the removal is removed by the first cleaning device 9A.
, And the surface potential is initialized.

The recording medium P, on which the first and second images have been transferred to the respective surfaces, passes through the fixing device 20 and the heating means 24 while being carried on the surface of the intermediate transfer member 3. At this time, the fixing roller 22 and the heating roller 49 are heated to a temperature suitable for fixing an image, and are rotating while being in contact with the intermediate transfer body 3. As a result, the first and second images transferred to the recording medium P passing therethrough are simultaneously fixed to each surface of the recording medium P. Thus, a recorded image is obtained on each surface of the recording medium P.

The recording medium having passed through the fixing device 20 is separated from the intermediate transfer member 3 and guided by guides 25 and 26.
The arrow F is applied to the discharge stack 28 through the discharge roller pair 27.
Is discharged as indicated by.

The transfer residual toner adhering to the intermediate transfer member without being transferred to the recording medium is removed by the cleaning roller 30 in contact with the surface, and the intermediate transfer member portion after the cleaning is in contact with the surface. Heat pipe 34
Cooled by.

Also in the case of the above-mentioned second mode, first, the first image of the second page is formed on the second image carrier 2, and this image is formed on one side of the recording medium via the intermediate transfer member 3. The second image of the first page is formed on the first image carrier 2A, and is transferred to the other surface of the recording medium, and this operation is repeated. The page order of the images formed on each side of the recording medium stacked on the recording medium 28 can be aligned. Further, the first image formed on the surface of the second image carrier 2 is a normal image, and is transferred to the intermediate transfer member 3 to become a reverse image. By being transferred to one surface of the recording medium, a normal image is formed, and the second image formed on the first image carrier 2A is formed as a reverse image, which is transferred to the other surface of the recording medium. It becomes a normal image.

As described above, in the image forming apparatus of this embodiment, when the second image carrier 2 is mounted, the second image carrier 2
Is transferred to the intermediate transfer member 3, the transferred image is transferred to one surface of the recording medium P, and the image formed on the first image carrier 2A is transferred to the same recording medium P. It is configured so that image formation can be performed in a second mode in which a recorded image is transferred to the other surface to obtain a recorded image.

In the above-described second mode, before the first transfer of the first image on the second image carrier 2 onto the intermediate transfer member 3 and before the intermediate transfer member 3 makes one rotation, Since the transfer of the second image on the first image carrier to the recording medium is started, the time until the image is completely formed on both sides of the recording medium P can be shorter than in the first mode, and the productivity can be reduced. It can be even higher.

In the second mode, while the above-mentioned advantages are obtained, the first and second image carriers 2A and 2 are required. Accordingly, the cost of an image forming apparatus capable of forming an image in the second mode, and consequently, the price thereof, increase. Therefore, such an image forming apparatus is not suitable for a user who wants a low-cost image forming apparatus. However, the image forming apparatus of the present embodiment is configured so that the second image carrier 2 can be added in an optional manner. Therefore, if a two-sided image can be obtained, the image forming apparatus is less expensive than the image forming speed. A user who wants the apparatus may obtain an image forming apparatus without the second image carrier 2. Moreover, if the user later needs an image forming apparatus capable of forming an image in the second mode, the user can add the second image carrier 2 to the image forming apparatus that has been used so far. We can meet that demand. A user who wants an image forming apparatus capable of forming an image in the second mode from the beginning may obtain an image forming apparatus in which the second image carrier 2 is mounted in advance.

Further, in the image forming apparatus of the present embodiment, the second image carrier 2 and the image forming means for forming an image on the image carrier are constituted as the second image forming unit 11, The second image forming unit 11 and the second exposure device 12 are added as an option, and the second image forming unit 11 is mounted on an image carrier mounting portion including a second guide stay 52, and a second Second exposure apparatus 1
2 can be mounted and used, so that the cost of the image forming apparatus shown in FIG. 1 without such an image forming unit 11 and the exposure device 12 can be reliably reduced.

Here, when the second image carrier 2 is mounted on the main body 1 of the image forming apparatus and the mode switching means for automatically switching the image forming mode to the second mode is provided by the mounting, the complexity is increased. Image formation can be performed in the second mode without performing an operation. For example, a sensor (not shown) is provided on the back side of the image forming apparatus main body 1, and the second image forming unit 11 is pushed from the near side of the image forming apparatus main body 1 to the back side, and the second image carrier 2 is moved. Image forming apparatus main body 1
When the image forming mode is set at a predetermined position, the sensor detects the mounting of the second image forming unit 11 and automatically switches the image forming mode to the second mode based on the detection signal. . By switching the mode, the second transfer unit 13 is connected to the high voltage power supply.

In the illustrated image forming apparatus, the second image carrier 2 is formed on the first image carrier 2A regardless of whether the second image carrier 2 is mounted on the image forming apparatus main body 1 or not. The third mode in which only the transferred image is transferred to the recording medium P can be selected. In this case, even when the second image carrier 2 is mounted, no image is formed on the second image carrier 2 and only the first image carrier 2A described above is formed. An image is formed in exactly the same way. Although the second transfer means 13 does not operate, the intermediate transfer member 3 is driven to rotate in the direction of arrow A, and when the second image carrier 2 is mounted, the image carrier 2 is also rotated as shown in FIG. Is driven to rotate in the direction indicated by the arrow B2. In the third mode, the second image carrier 2 may be separated from the intermediate transfer member 3.

Also in the third mode, the recording medium P sent from the paper feeder 15 or 19 as described above rotates the registration roller pair 18 to rotate the image formed on the first image carrier 2A. The image formed on the first image carrier 2A is transferred to the recording medium P by the first transfer means 13A. Is done. The recording medium on which the image has been transferred is carried on the intermediate transfer body 3 and moves together with the intermediate transfer body 3, and the image transferred on the recording medium is formed by the cooperation of the fixing device 20 and the heating unit 24. It is fixed on a recording medium. Thereafter, the recording medium is separated from the intermediate transfer body 3, is guided by guides 25 and 26, is discharged onto a discharge stack 28 through a pair of discharge rollers 27, and is stacked here. At this time, the recording medium is placed on the discharge stack unit 28 with the surface on which the image is formed facing downward. Therefore, when a document of several pages is processed in order from one page, and the recording medium on which each image is formed is stacked on the discharge stack unit 28, the page order of each image is aligned. Third
The switching to the mode is performed, for example, by operating the operation unit 51 of the image forming apparatus shown in FIGS. 3 and 4 or by operating the host computer 61 connected to the image forming apparatus. The same applies to a later-described fourth mode or switching to the first mode.

Here, the second image forming unit 11 and the second exposing device 12 are mounted on the main body 1 of the image forming apparatus, and the image is formed in the above-described second mode. When no toner is left in the developing case 71 of No. 8,
The image forming operation in the second mode may be prohibited by the user operating the operation unit 51 or the host computer 61 or automatically, and the above-described third mode may be selected. According to this configuration,
When the toner in the second developing device 8 runs out, the first
An image can be formed on one side of the recording medium P using the image carrier 2A, and the image forming operation can be continued. Even when there is no spare toner at hand, there is no need to interrupt the image formation itself. In this case, the third
Is displayed on the display unit of the operation unit 51 and the display of the host computer 61.

As described above, when the second image carrier 2 is mounted on the image forming apparatus main body 1 and the image forming operation is performed, the toner for forming the image on the second image carrier 2 is discharged. By configuring so that the third mode is selected when there is no more, the image forming apparatus can be used more effectively.

Further, the image formed on the second image carrier 2 may be transferred to the intermediate transfer member 3 and a fourth mode in which only the image is transferred to the recording medium P may be selectable. In this case, an image is formed only on the second image carrier 2 without forming an image on the first image carrier 2A as described above, and this is transferred to the intermediate transfer member 13 by the second transfer means 13. Transfer to 3. The transfer residual toner adhering to the second image carrier 2 after the image transfer is removed by the second cleaning device 9, and the second image carrier 2 after the removal is removed by the second charge removing device 6.
To eliminate the charge.

After the polarity of the image transferred on the intermediate transfer member 3 is reversed by the charger 14, the image is transferred to a recording medium sent between the intermediate transfer member 3 and the first image carrier 2A. The image is transferred by the first transfer unit 13A. The image is fixed by the fixing device 20 and the heating unit 24, and the recording medium is discharged to the discharge stack unit 28. Thus, an image is formed only on one side of the recording medium.

Here, when the developing device 8A of the first image forming unit 11A runs out of toner, the user operates the operation unit 51 or the host computer 61, or automatically, the second or the second. The image forming operation in the third mode is prohibited, and the above-described fourth mode can be selected. Also in this case, the fact that the fourth mode is selected is displayed on the display unit of the operation unit 51 and the display of the host computer 61. As described above, when the toner for forming an image on the first image carrier 2A runs out, the fourth mode is selected so that the image forming apparatus can be stopped without stopping.
The operation of forming an image on one side of the recording medium P can be continued.

Further, the first mode can be selected even when the second image carrier 2 is mounted on the main body 1 of the image forming apparatus. As a result, when the toner for forming an image on the second image carrier 2 runs out, the first mode is selected by a user's operation or automatically, and the recording medium is formed only by the first image forming unit 11A. An image can be formed on both sides of P.

When the first mode is executed by mounting the second image carrier 2 on the main body 1 of the image forming apparatus, the image transferred from the first image carrier 2A to the intermediate transfer body 3 is fixed.
When the image passes through the cleaning roller 30 and the heat pipe 34, the fixing device 20 and the heating unit 24 become inactive as described above.
0 and the heat pipe 34 on the intermediate transfer member surface side is separated from the surface of the intermediate transfer member 3 as described above.
In addition, when the image on the intermediate transfer body passes through the second image carrier 2, the second image carrier 2 is also configured to be separated from the surface of the intermediate transfer body 3, and the image is formed on the second image carrier 2. It is preferable that the image bearing member 2 is configured not to be disturbed.

Whether or not each of the above modes can be executed depends on whether or not the first and second image carriers 2A and 2 are mounted and whether or not the first and second developing devices 8A and 8 have toner. Is summarized in Table 1 below. In the table, the circles indicate that the respective modes can be executed, and the print prohibition indicates that the image forming operation in any of the modes is prohibited. The “first toner” indicates whether the first developing device 8A has toner, and the “second toner” indicates whether the second developing device 8 has toner.

[0093]

[Table 1]

Further, as shown in FIG. 2, it is preferable that the first image carrier 2A and the second image carrier 2 are formed in substantially the same shape and substantially the same size. By sharing the first and second image carriers 2A and 2 in this way, the types of components of the image forming apparatus can be reduced, and when the image carriers 2A and 2 reach the end of their life and are replaced. Can also be simplified.

Here, when the image forming operation in each mode described above is being performed, the recording medium P may be jammed in the transport path. When such a recording medium jam occurs, the image forming operation is interrupted, the rotation of the first and second image carriers 2A and 2 and the intermediate transfer body 3 is stopped, and the recording medium jammed by the user is removed. Will do. Further, the image carriers 2A and 2 and the intermediate transfer member 3 or other elements are repaired.
Inspections may need to be performed, or even end-of-life elements may need to be replaced. In the illustrated example, when the first and second image forming units 11A and 11 reach the end of their life, each of the units can be replaced with a new image forming unit.

A front door 37 is provided on the main operation surface side of the image forming apparatus main body 1 as shown in FIGS. 3 and 5 so that the above various maintenance operations can be performed. By opening, the inside of the image forming apparatus main body can be opened. As shown in FIGS. 1 and 2, an upper part of the upper part of the image forming apparatus main body 1 is rotatably opened and closed with respect to another image forming apparatus main body part via a support shaft 38. By opening the upper door 39 as shown by a chain line in FIGS. 1 and 2, the upper part of the image forming apparatus main body 1 can be opened. When the front door 37 or the upper door 39 is opened during the operation of the image forming apparatus, a switch (not shown) is turned off, and the image forming operation is automatically stopped.

As described above, the upper door 39 is opened to remove the jammed recording medium, or the front door 39 is opened to remove the jammed recording medium, the intermediate transfer member 3 and the image forming units 11A and 11A. And the like can be removed from the image forming apparatus main body.
When the above-described maintenance work is performed in a state where the intermediate transfer members A and 2 are in contact with each other as shown in FIG. 2, the jammed recording medium strongly hits the image carrier 2A and the intermediate transfer member 3, or There is a possibility that the intermediate transfer member 3 and the image carriers 2A and 2 come into strong contact with each other, and their surfaces may be damaged.

Therefore, in the image forming apparatus of this embodiment,
The first position at which the intermediate transfer member 3 contacts the first and second image carriers 2A, 2 as shown in FIG. 2, and the first and second image carriers 2A as shown in FIG. , 2 are operably supported between a second position remote from the second position. This allows
After the upper door 39 and the front door 37 are opened to stop the image forming operation, the intermediate transfer body 3 is moved to the first and second image carriers 2.
A, 2 so that the image carrier 2
The above-described maintenance work can be performed easily without damaging the surfaces of the A, 2 and the intermediate transfer body 3. After the work is completed, the image forming operation can be restarted by bringing the intermediate transfer body 3 into contact with the first and second image carriers 2A and 2 again and closing the upper door 39 and the front door 37.

Further, in the image forming apparatus of this embodiment, as can be seen from FIGS. 2 and 7, the intermediate transfer member 3 is swung in the direction of arrow H so that the intermediate transfer member 3 is moved to the first position ( The intermediate transfer body 3 is supported so as to operate between the second position (FIG. 7) and the second position (FIG. 7), whereby the intermediate transfer body 3 is rotated by a slight angle in the direction of arrow H. Then, the intermediate transfer member 3 and the first and second image carriers 2A,
2 or the intermediate transfer member 3 and the first and second image carriers 2A and 2 can be brought into contact with each other, so that the work of contact and separation can be easily performed.

Further, in the illustrated image forming apparatus, as shown in FIG.
The intermediate unit 41 is constituted by the support 40 that supports the intermediate transfer body 3. In the example shown in FIG.
The support body 40 includes front and rear side plates 42 and 43 and these side plates 4.
And a connecting plate 44 for integrally connecting the rollers 4, 5 for supporting the intermediate transfer member 3 to the side plates 42, 43, respectively.
Are rotatably supported.

In the image forming apparatus of the present embodiment, although not shown in FIG. 5, the first and second transfer means 13A and 13 comprising the transfer roller shown in FIG. A plurality of heat pipes 34 are provided on both side plates 42 and 43.
, And the case 32 of the cleaning device 29 is integrally assembled with the support 40, and these elements 13A, 13, 49, 34, and 29 also constitute components of the intermediate unit 41.

As shown in FIGS. 5 and 6, a base end portion of a support shaft 46 extending toward the front side of the image forming apparatus main body is fixed to the rear side plate 45 of the image forming apparatus main body 1.
The front end of the support shaft 46 is free, and is supported in a cantilever manner with respect to the image forming apparatus main body 1. The support shaft 46 is provided with holes 4 formed in both side plates 42 and 43 of the support 40 constituting the intermediate unit 41.
7, 48, and as can be seen from FIGS. 1, 2 and 6, the whole of the intermediate unit 41 is supported by the support shaft 46.
It is swingably supported. The support shaft 46 traverses the inside of the intermediate transfer body 3 formed of a belt.

Even if the support shaft 46 is supported on the image forming apparatus main body 1 so as to be rotatable around the center axis of the support shaft 46, the intermediate unit 41 is supported so as to be unable to rotate relative to the support shaft 46. In short, the point is that the intermediate unit 41 is supported by the support shaft 46 so that the intermediate unit 41 can swing around the central axis of the support shaft 46.

At this time, as shown in FIGS. 5 and 6, guide plates 70 (FIGS. 1, 2 and 7) concentric with the respective holes 47 and 48 are formed in both side plates 42 and 43 of the support 40. Is not shown)
Can be fixed, and the support shaft 46 can be inserted into the guide tube 70.

As described above, since the intermediate unit 41 is supported by the support shaft 46 provided in the main body of the image forming apparatus, by swinging the intermediate unit 41 around the center axis of the support shaft 46, The transfer body 3 can be operated between a first position (FIG. 2) and a second position (FIG. 7), and an intermediate transfer body is provided for the first and second image carriers 2A and 2A. 3 can be brought into and out of contact with each other in a stable state almost simultaneously.

When the intermediate transfer member 3 occupies the first position,
It is preferable to provide a lock device (not shown) for inhibiting the swing of the intermediate unit 41 so that the intermediate transfer body 3 is stably held at the first position. By opening the front door 37 and unlocking the lock device, the intermediate unit 41 can be freely swung by hand,
The intermediate transfer member 3 can be brought to the second position.

In the image forming apparatus of this embodiment, as shown in FIG. 8, the center I of the swing of the intermediate transfer member 3 (the center axis of the support shaft 46 in this example) is an intermediate transfer belt made of an endless belt. It is located inside the body 3, ie inside the loop of the belt.

Further, the center I is, as shown in FIG.
It is located in a region between the first image carrier 2A and the second image carrier 2, that is, a region J indicated by a dashed line in FIG. According to this configuration, the intermediate transfer body 3 or the intermediate unit 41 is rotated by a small angle from the first position around the center I, and the intermediate transfer body 3 is moved to the first and second image carriers 2A. , 2.
A large gap can be secured between the intermediate transfer member 3 and the first and second image carriers 2A and 2A. Accordingly, the above-described maintenance work can be easily performed, and the work of contacting and separating the intermediate transfer body 3 with the first and second image carriers 2A and 2 can be easily performed.

At this time, as shown in FIG.
When it is located on the line L connecting the central axis of the first image carrier 2A and the central axis of the second image carrier 2, the above-described effect can be further ensured.

The intermediate unit 41 is slidably supported on the support shaft 46 in the axial direction. Therefore, after opening the front door 37 as shown in FIG. 5, the intermediate unit 41 is rotated to move the intermediate transfer body 3 to the first position shown in FIG.
From the position shown in FIG. 7 to the second position shown in FIG. 7, and then pulling out the intermediate unit 41 along the support shaft 46 toward the near side indicated by the arrow M, thereby pulling out the intermediate unit 41 as shown in FIG. It can be removed from the image forming apparatus main body 1. Conversely, the holes 47 and 48 of the intermediate unit 41 are
6, the intermediate unit 41 is pushed into the back side indicated by the arrow N, and the intermediate unit 41 is turned again to bring the intermediate transfer body 3 to the first position shown in FIG. The unit 41 can be mounted at a predetermined position in the main body of the image forming apparatus. As described above, by moving the intermediate unit 41 along the axial direction of the support shaft 46, the intermediate unit 41 is attached to the support shaft 4 so that the intermediate unit 41 can be attached to and detached from the image forming apparatus main body 1.
6 to support.

According to the above configuration, since the intermediate unit 41 including the intermediate transfer body 3 can be attached and detached by using the support shaft 46 as a guide member, the attaching / detaching operation can be easily performed and the intermediate unit 41 is swung. Support shaft 46 for
However, since it also serves as a guide member for attaching and detaching the intermediate unit 41, the configuration of the image forming apparatus can be simplified.

By the way, as described above with reference to FIGS. 3 and 5, the front door 37 is provided on the main operation surface side of the image forming apparatus main body 1. Generally, it is the side facing the user who operates the image forming apparatus. This side is also the front side of the image forming apparatus main body, and the opposite side is the back side of the image forming apparatus main body 1. As shown in FIG. 3, the side on which the operation unit 51 is provided is usually the main operation surface side of the image forming apparatus main body 1.

As described above, the support shaft 46 extends from the back side of the image forming apparatus main body 1 in a cantilever shape substantially horizontally to the front side, that is, the main operation surface side. The intermediate unit 41 can be attached to and detached from the image forming apparatus main body 1 by opening the front door 37 provided on the side. In this manner, the support shaft 46 is attached so that the intermediate unit 41 can be attached to and detached from the main body 1 of the image forming apparatus.
Is arranged.

According to the above-described configuration, the user who operates the image forming apparatus can perform the work of attaching and detaching the intermediate unit 41 from the operation surface side of the image forming apparatus main body 1, so that the work can be performed easily. Sex is enhanced. In addition,
As shown in FIG. 3, the sheet cassette 16 shown in FIGS. 1 and 2 is also configured to be pulled out from the main operation surface side of the image forming apparatus main body 1 so that a recording medium can be replenished therein.

In the image forming apparatus of the present embodiment, as described above, the first image forming unit 11A is constituted by the first image carrier 2A and the plurality of image forming means disposed therearound. However, it is not always necessary to use a large number of image forming units as components of the first image forming unit 11A. This is the same in the second image forming unit 11. In short, the first image carrier 2A and at least one image forming means for forming an image on the first image carrier 2A are configured as a first image forming unit 11A, and the second image The carrier 2 and at least one image forming unit for forming an image on the second image carrier 2 are configured as a second image forming unit 11.

At this time, in the image forming apparatus of this embodiment,
The first and second image forming units 11A and 11 are configured to be attached to and detached from the image forming apparatus main body 1 from the same surface side.
A and 11 are configured to be mounted on the image carrier mounting portion including the guide stays 52A and 52 described above. In the illustrated example, the first and second image forming units 11A, 11A
Is configured to be attachable to and detachable from the image forming apparatus main body 1 from the main operation surface side, similarly to the case of the intermediate unit 41.

Specifically, as shown in FIG. 1, FIG. 2, FIG. 5, FIG. 7, FIG. 9 and FIG.
The above-mentioned first and second guide stays 52A, 52 extending from the back side to the front side are fixed respectively, and the first and second image forming units 1 are attached to the respective guide stays 52A, 52.
The unit cases 10A and 10 of 1A and 11 are slidably supported in the front and rear directions M and N of the image forming apparatus main body 1 (FIG. 5). Accordingly, after opening the front door 37 and operating the intermediate unit 41 so that the intermediate transfer body 3 occupies the second position shown in FIG. 7, the first and second image forming units 11A and 11 are operated. Is pulled toward the user, the image forming units 11A and 11 are connected to the image forming apparatus main body 1 as shown in FIG.
(FIG. 5 shows only one image forming unit 11). Conversely, the first and second image forming units 1
The unit cases 10A, 11 of 1A, 11 are fitted into the first and second guide stays 52A, 52, respectively, and these are pushed into the inner side of the image forming apparatus main body 1, so that these image forming units 11A, 11 can be assembled. It can be mounted at a predetermined position in the image forming apparatus main body. At this time, when each of the image forming units 11A and 11 is mounted at a predetermined position in the main body of the image forming apparatus, a lock device (not shown) for locking the image forming unit at that position is provided, and the lock is released. It is preferable that the image forming units 11A and 11 be configured to be able to be pulled out to the near side.

As described above, since the first and second image forming units 11A and 11 can be detached from the main operation surface side of the image forming apparatus main body 1, maintenance and inspection work and replacement of these image forming units 11A and 11 can be performed. Work can be easily performed. If handles (not shown) are provided on the first and second image forming units 11A and 11, these can be more easily handled. The same applies to the intermediate unit 41.

At this time, the first and second image forming units 11
A and 11 are first and second guide stays 52A and 52, respectively.
It is preferable to be configured so that it can be attached to any of the above. For example, the first and second image forming units 11A, 11A
Is detached from the image forming apparatus main body 1, the second image forming unit 11 supported by the second guide stay 52 is fitted to the first guide stay 52 </ b> A, and this is inserted into the image forming apparatus main body. By pushing the image forming unit to the side, the image forming unit is mounted in the main body of the image forming apparatus, and can be used as the first image forming unit. Similarly, the first image forming unit 11A, which has been supported by the first guide stay 52A, is fitted to the second guide stay 52, and is pushed in to be mounted in the image forming apparatus main body. The image unit can be used as a second image forming unit.

As described above, the first image forming unit 11A
The first image forming unit and the second image forming unit are configured such that one image forming unit of the second image forming unit 11 can be mounted at a mounting position of the other image forming unit. For example, the first image forming unit 11A and the second
The image forming units 11 may have substantially the same size and substantially the same shape. As described above, since the first and second image forming units 11A and 11 have the same configuration, even if any of the image forming units is used as the first image forming unit, Can be used as the second image forming unit to form a predetermined image on each image carrier.

Thus, the first and second image forming units 1
By making the units 1A and 11 compatible, when replacing the image forming unit, the user can use any image forming unit.
Since this can be attached to any mounting position,
The mounting mistake can be eliminated. Moreover, when storing the image forming units, it is not necessary to store the first image forming unit and the second image forming unit separately. Also,
Since the same image forming unit is used as the first and second image forming units 11A and 11, the number of types of components can be reduced, and the manufacturing cost can be reduced.

By the way, as described above with reference to FIG. 2, the first charging device 7A of the first image forming unit 11A.
A first exposing device 12A for forming an image on the first image carrier 2A is provided between the first developing device 8A and the second developing device 8A. Carrier 2
Is provided with a second exposure device 12 for forming an image. These exposure devices 12A, 12 may also be configured as components of the first and second image forming units 11A, 11; however, in the image forming apparatus of the present embodiment, as described above, And the second exposure devices 12A and 12
And the second image forming units 11A and 11 are configured as separate elements. This generally means that the exposure apparatus 12
A and 12 have a longer life than the image carrier and the image forming means disposed therearound. Therefore, if the exposure apparatus is configured as a component of the image forming unit and can be replaced as a whole,
This is because even an exposure apparatus that can still be used sufficiently may be replaced.

When exposing devices 12A and 12 have reached the end of their life and are to be replaced or when exposing devices 12A and 12 are to be cleaned, separately from image forming units 11A and 11
Only the respective exposure devices 12A and 12 are used in the image forming apparatus main body 1
Can be taken from Further, the first and second image forming units 11A and 11 can be taken out of the image forming apparatus main body 1 while the first and second exposure devices 12A and 12 are left inside the image forming apparatus main body 1. First and second
The first image forming unit 11A and the second image forming unit 11 can be attached to and detached from the image forming apparatus main body 1 respectively.

More specifically, as shown in FIG. 2, the first and second guide stays 52A, 52 are provided on the image forming apparatus main body 1 in the longitudinal direction M, N (FIG. 5), First and second guide rails 53 extending in parallel directions
The exposure devices 12A and 12 are guided by the guide rails 53A and 53, respectively. As a result, each of the exposure devices 12A, 12 is pulled out toward the near side of the image forming apparatus main body 1 along the respective guide rails 53A, 53, or is pushed into the back side, and is mounted at a predetermined position in the image forming apparatus main body. be able to. As described above, the first and second exposure devices 12A and 12 can also be attached to and detached from the image forming apparatus main body 1 from the main operation surface side of the image forming apparatus main body 1.

By the way, the first and second exposure devices emit a laser beam light-modulated in accordance with the write information and scan the laser beam in the main scanning direction of the image carriers 2A, 2. Although a writing unit or the like can be used, in the illustrated example, an array of exposure devices 12A and 12 having a large number of light sources arranged in a line, for example, a large number of LEDs (light emitting diodes) is used. The light from each light source passes through a lens (not shown), forms an image on the surfaces of the image carriers 2A and 2 uniformly charged by the charging devices 7A and 7, and forms electrostatic images corresponding to the written information on the surfaces. Form a latent image. As such an exposure apparatus, for example, an optical writing apparatus described in Japanese Utility Model Publication No. 2-42454 proposed by the present applicant can be used.

The exposure apparatus 12A, 1 in the form of an array as described above
2 is very small in size compared to the laser writing unit, so that the space occupied by the exposure devices 12A and 12 in the image forming apparatus main body 1 can be reduced, and the image forming apparatus main body 1 can be downsized. Becomes Since the first and second exposure devices 12A and 12 are detachably supported on the image forming apparatus main body 1 in a direction substantially parallel to the support shaft 46, the respective exposure devices 12A and 12 can be easily mounted. By attaching and detaching, maintenance work can be performed.

At this time, the first and second exposure apparatuses 12A,
12 have the same configuration and are formed in the same shape and size. Therefore, both of these exposure apparatuses can be mounted on any of the guide rails 53A, 53 just like the case of the image forming units 11A, 11.
By making the exposure devices 12A and 12 compatible as described above, there is no danger of mounting the exposure device in an incorrect position, and the exposure devices are stored separately as the first and second exposure devices. Troublesomeness can be eliminated. The first and second exposure devices 12A and 12 have a difference in the function of forming a mirror image and a normal electrostatic latent image on each image carrier 2A and 2, respectively. Can be controlled freely.

As described above, the intermediate unit 41 is supported so as to be able to be pulled out to the front side of the image forming apparatus main body 1, but the intermediate transfer body 3 occupies the first position. The body 3 is composed of first and second image carriers 2A,
If the intermediate unit 41 is accidentally pulled out to the near side while in contact with the intermediate transfer member 2, the intermediate transfer member 3 and the first and second image carriers 2A and 2 rub against each other, These surfaces may be scratched.

Therefore, in the image forming apparatus of this embodiment,
When the intermediate transfer member 3 occupies the first position shown in FIG. 2, there is provided an intermediate unit detachment prevention unit for preventing the intermediate unit 41 from being pulled out of the image forming apparatus main body 1.

First and second image forming units 11A, 11
Also, the intermediate transfer body 3 is supported so as to be able to be pulled out toward the image forming apparatus main body 1 on the front side thereof.
Are in contact with the first and second image carriers 2A and 2
If the first and second image forming units 11A and 11 are pulled out to the near side, the surfaces of the intermediate transfer member 3 and the image carriers 2A and 2 may be damaged.

Therefore, in the image forming apparatus of this example, when the intermediate transfer body 3 occupies the first position, the first and second image forming units 11A and 11 are pulled out from the image forming apparatus main body 1. There is provided an image forming unit detachment preventing means for inhibiting the operation.

FIG. 5 shows that the front door 37 is opened and the intermediate unit 4 is opened.
1 shows a state in which the first and first and second image forming units 11A and 11 are removed from the image forming apparatus main body 1 (the second image forming unit is not shown). FIG. FIG. 9 and FIG. 10 are schematic side cross-sectional views when the image forming apparatus 1 is mounted in the image forming apparatus main body. FIG. 3 is a schematic front view when the front door 37 is opened. As shown in these figures, the intermediate unit 41 is attached to a cover front portion 55 which is a main operation surface side of the exterior cover 54 of the image forming apparatus main body 1. A notch 56 is formed in a shape that allows the intermediate unit 41 to pass through when attaching and detaching.

FIG. 9 shows the first transfer member 3 not shown in FIG. 9 in which the intermediate transfer member 3 contacts the first and second image carriers 2A and 2A.
3 shows the state of the intermediate unit 41 when the intermediate unit 41 occupies the position shown in FIG.
When viewed from the main operation surface side, a part 58 of the support member 40 of the intermediate unit 41 is located at a position closer to the back of the image forming apparatus main body than the cover front portion 55. It is positioned so as to overlap with a stopper 57 constituted by the portion of the portion 55. Therefore, when the intermediate transfer member 3 is at the first position in contact with the first and second image carriers 2A and 2, even if the intermediate unit 41 is to be pulled out to the near side, a part 58 of the support member 40 is not used. Interferes with the stopper 57, and the draw-out of the intermediate unit 41 is prohibited.

While holding the intermediate transfer member 3 in the main body of the image forming apparatus, the intermediate transfer member 3 is rotated to the position shown in FIG. 10 to separate the intermediate transfer member 3 from the first and second image carriers 2A, 2. To the second position, the support 4 of the intermediate unit 41
0 occupies a position that does not interfere with the stopper 57. Therefore, if the intermediate unit 41 is pulled forward, it can be pulled out of the image forming apparatus main body without any trouble. The stopper 57 may be formed of a member other than the outer cover, or an independent stopper member may be fixed to the image forming apparatus main body 1 and used as a stopper. In any case, the stopper is provided on the image forming apparatus main body side.

As described above, when the intermediate transfer member 3 occupies the first position, the intermediate unit detachment preventing means shown as an example in the figure interferes with the intermediate unit 41 and inhibits the intermediate unit 41 from being pulled out. The intermediate unit 41 and the stopper 57 do not interfere with each other so that the intermediate unit 41 can be pulled out when the intermediate transfer body 3 occupies the second position. The stopper 57 is provided at the position.

As shown in FIGS. 5, 9 and 10, the support 40 of the intermediate unit 41 has the first and second
Are formed respectively, and the first and second projections 59A, 59 are formed.
Unit case 10 of image forming units 11A and 11
A and 10 have first and second concave portions 60A and 60, respectively. When the intermediate transfer member 3 occupies the first position, and thus the intermediate unit 41 is in a state where the pull-out is prohibited by the above-described stopper 57, the first and second protrusions of the intermediate unit 41 as shown in FIG. 59
A, 59 are the first and second image forming units 11A, 11
Respectively engage with the first and second concave portions 60A, 60. Therefore, the first and second image forming units 11A, 11A
Is prohibited from moving toward the front of the image forming apparatus main body 1 with respect to the intermediate unit 41. At this time, since the intermediate unit 41 is prohibited from being pulled out to the near side of the image forming apparatus main body by the stopper 57, even if the first and second image forming units 11A and 11 are pulled to the near side, the image forming is performed. The units 11A and 11 are not pulled out toward the image forming apparatus main body.

By rotating the intermediate unit 41 to the position shown in FIG. 10, the intermediate transfer member 3 is moved to the first and second image carriers 2.
When the first and second projections 59A and 59 of the intermediate unit 41 are brought to the second position where they do not come into contact with the first and second image forming units 11A and 11, respectively. 60A and 60A, respectively. Therefore, in this state, the first and second image forming units 11A and 11 can be pulled out toward the near side of the image forming apparatus main body 1, respectively.

In the above-described example, the projections 59A and 59 are provided on the side of the intermediate unit 41, and the concave portions 60A and 60 are provided on the first and second image forming units 11A and 11 to form the engaging portions. However, conversely, these engaging portions can be configured by providing projections on the first and second image forming units and providing recesses on the intermediate unit.

In any case, the image forming unit detachment preventing means of this embodiment inhibits the first and second image forming units 11A and 11 from being pulled out when the intermediate transfer body 31 occupies the first position. As described above, the first and second image forming units 1
When the intermediate transfer member 3 occupies the second position, the first and second image forming units 11A and 11 can be pulled out. Thus, the engagement of the engagement portion is released.

The above-mentioned intermediate unit detachment preventing means,
By providing the image forming unit detachment preventing means, it is possible to prevent a drawback that the intermediate transfer member 3 and the first and second image carriers 2 and 2A are pulled out in a contact state.

As described above with reference to FIGS. 1 and 2, the image forming apparatus of this embodiment transfers the image on the intermediate transfer member 3 to the recording medium P, and then transfers the image to the intermediate transfer member 3.
A cleaning device 29 for an intermediate transfer member having a cleaning roller 30 which is an example of a cleaning member for removing transfer residual toner adhered thereon is provided, but the second image carrier 2 is attached to the image forming apparatus main body 1. When performing image formation in the second mode described above, the cleaning member does not need to be brought into contact with or separated from the surface of the intermediate transfer body 3, but is always brought into contact with the surface of the intermediate transfer body Can be left in place. This is the same when performing image formation in the above-described third and fourth modes.

Therefore, it is preferable that the cleaning member is always in contact with the intermediate transfer member 3 when the second image carrier 2 is mounted on the main body 1 of the image forming apparatus. For example, when a mode other than the first mode is selected, the cleaning roller 30 is kept pressed against the surface of the intermediate transfer member. With this configuration, it is possible to eliminate the impact that occurs when the cleaning roller 30 comes into contact with or separates from the intermediate transfer member 3. A high quality image can be formed.

As described above with reference to FIG. 2, in the image forming apparatus of this embodiment, the first transfer unit 1
3A, the first image transferred to the intermediate transfer member 3 and the second image formed on the first image carrier 2A are simultaneously transferred to one surface and the other surface of the recording medium P, respectively. Therefore, the transfer process and the configuration of the image forming apparatus are simplified as compared with a case where the first and second images are transferred to each surface of the recording medium by separate transfer units. be able to.

Of course, the first image on the intermediate transfer member and the first image
The second image on the image carrier is transferred by separate transfer means.
The image may be transferred to each side of the recording medium. In such a case, usually, one of the first image and the second image is first transferred to the recording medium, and the other is recorded later. Transferred to media.

The charge polarity of the first image on the intermediate transfer body 3 immediately before the transfer by the transfer means 13A shown in FIG. 2 is set to the first polarity, and the second image on the first image carrier 2A is set to the first polarity. Assuming that the charging polarity of the image is the second polarity, the transfer unit 13A transfers the first image on the intermediate transfer member charged to the first polarity to the first image.
Image carrier 2 charged to a second polarity opposite to the polarity of
The second image on A is configured to be transferred to one surface and the other surface of the recording medium P, respectively. Thus, the first image and the second image are shared by the common transfer unit 13A.
Can be simultaneously transferred to each surface of the recording medium.

Further, in the image forming apparatus of this embodiment,
As described above, the second image and the first image charged with the second polarity are formed on the first and second image carriers 2A and 2 respectively, and the first image transferred to the intermediate transfer member 3 is formed. Before the first image is transferred to the recording medium,
Since the polarity conversion means for converting the first polarity is provided, even if the first and second image forming units 11A and 11 have the same configuration, the first image and the second image are simultaneously recorded on the recording medium. At the time of transfer, the charged polarities of the respective images are set to opposite polarities, and these images can be reliably transferred to the respective surfaces of the recording medium P by the common transfer means 13A.

In the image forming apparatus of this embodiment, a transfer roller that rotates while being pressed against the back surface of the intermediate transfer member 3 is used as the first and second transfer units 13A and 13; A transfer unit including a brush, a blade, a brush roller, or the like, to which a transfer voltage is applied in contact with the back surface of the intermediate transfer member 3, or a transfer unit including a discharge charger spaced apart from the back surface of the intermediate transfer member 3; Can also. However, as shown in FIG.
And using the second transfer means 13A and 13 so that each roller thereof is pressed against the back surface of the intermediate transfer body 3,
During the transfer of the first and second images, the intermediate transfer member 3 and the recording medium P can be pressed against the first and second image carriers 2A and 2 in close contact with each other. It is possible to increase.

In the image forming apparatus shown in FIGS. 1 and 2, the image transferred to the surface of the recording medium P before leaving the intermediate transfer member 3 is fixed by the fixing device 20 as described above. Is configured. The fixing device 20
It is arranged so that the image transferred on the surface of the recording medium P superimposed on the intermediate transfer body 3 is fixed.

As will be described later with reference to FIG. 11, the fixing device 20 is disposed separately from the intermediate transfer member 3, and the image formed on the surface of the recording medium remote from the intermediate transfer member 3 is fixed to the fixing device. However, according to this configuration, the recording medium distant from the intermediate transfer body 3 is not supported by the intermediate transfer body 3, so that the conveyance stability thereof is reduced, and the recording medium There is a possibility that the image formed of the unfixed toner is disturbed.

On the other hand, if the respective images transferred to the recording medium before leaving the intermediate transfer member 3 are fixed as in the image forming apparatus shown in FIGS. Since the recording medium moving from the position to the fixing position can be held by the intermediate transfer body 3, the conveyance stability thereof is improved, and during this time, a problem that the image formed of the unfixed toner is disturbed can be prevented, and the quality of the image after fixing is improved Can be increased.

The fixing device 20 has a fixing roller 22 which is an example of a fixing member for fixing an image by contacting the recording medium P superimposed on the intermediate transfer member 3. When the image forming apparatus 2 is mounted on the image forming apparatus main body 1 to form an image in the second mode, the fixing roller 22
It is not necessary to make contact with / separate from. The same applies when performing image formation in the third and fourth modes. Therefore, when the second image carrier 2 is mounted on the main body 1 of the image forming apparatus, it is preferable that the fixing member is always in contact with the intermediate transfer body 3 directly or via a recording medium. For example, when a mode other than the first mode is selected, the fixing roller 22
Is kept pressed against the surface of the intermediate transfer member. With this configuration, the fixing roller 2 with respect to the intermediate transfer body 3
Thus, it is possible to eliminate a shock caused by the contact and separation of the lens 2 and to form a high-quality image without shock jitter.

As can be seen from FIG. 7, the intermediate transfer member 3
Is brought to a second position separated from the first and second image carriers 2A, 2 when the intermediate transfer member 3
In this example, the fixing roller 22 is disposed so as to be separated from the fixing roller 22. Therefore, when the intermediate unit 41 is attached to and detached from the main body of the image forming apparatus, it is possible to prevent the fixing device 20 from slidingly contacting the intermediate transfer body 3 and to prevent the surface of the intermediate transfer body 3 from being damaged. If the intermediate transfer member 3 is brought to the first position shown in FIGS. 1 and 2, the fixing roller 22 of the fixing device 20 can be brought into contact with the intermediate transfer member 3, and the above-described fixing operation can be performed without any trouble. It can be carried out.

The fixing device 20 shown in FIGS. 1 and 2 abuts against the intermediate transfer member 3 directly or via a recording medium, and is configured to fix an image on the recording medium at least by the action of heat. Therefore, the intermediate transfer member 3 is also heated to a high temperature, and the first image carrier 2
When the image is transferred, the toner may be fused to the surface of the intermediate transfer member. Further, heat is applied to the second image carrier 2, and the image carrier 2 may be deteriorated early.

However, in the image forming apparatus of this embodiment, as described above, the moving direction of the surface of the intermediate transfer member is
Cooling that cools the intermediate transfer member downstream of the fixing position where the fixing is performed and upstream of the transfer position where the first image is transferred from the second image carrier 2 to the intermediate transfer member 3. Since the means 33 is provided, the temperature of the intermediate transfer body 3 can be reduced before the first image is transferred from the second image carrier 2 onto the intermediate transfer body. This can prevent the above-described problem from occurring.

In addition, the intermediate transfer member 3 of the image forming apparatus of this embodiment
Comprises an endless belt that is wound around a plurality of rollers 4 and 5 and that is driven to run. The belt includes a heat-resistant base and a low-surface-energy surface layer laminated on the surface of the base. , The volume resistivity of the endless belt is 1
0 ^{6-10 12} If Ωcm to be set is advantageous.
For example, the base can be made of polyimide or polyamideimide having a thickness of 50 μm to 200 μm, and the surface layer can be made of a fluororesin such as Teflon (registered trademark). The surface resistivity of the belt surface is
For example, it is preferable to set the range of 10 ^{5 to} 10 ¹² Ω / □.

By setting the resistivity of the intermediate transfer member 3 composed of a belt as described above, the transfer efficiency of the first image from the second image carrier 2 to the surface of the intermediate transfer member can be increased. Moreover, by lowering the surface energy of the surface, the transfer efficiency of the image from the intermediate transfer body 3 to the recording medium can be increased. Further, the intermediate transfer member 3 includes
Although a large amount of heat is applied from the fixing roller 22 and the heating means 24, the problem that the intermediate transfer body 3 is thermally deteriorated at an early stage can be prevented by forming the base of the intermediate transfer body 3 from a heat resistant material as described above. The configuration in which the image is thermally fixed with the recording medium superimposed on the intermediate transfer member 3 can be realized without any trouble.

As shown in FIG. 3, an image forming system can be formed by connecting the above-described image forming apparatus and a host device such as a host computer 61. An indication that the carrier 2 is attached to the image forming apparatus main body 1 is displayed on at least one of the display unit of the operation unit 51 of the image forming apparatus itself and the host device connected to the image forming apparatus. With such a configuration, it is possible to prevent an erroneous setting of the image forming mode and the like.

The instructions to the image forming apparatus, such as image forming conditions, are sent to the host computer 61 or the image forming apparatus main body 1.
Can be performed by using the operation unit 51 provided in the. For example, by pressing a double-sided button of the operation unit 51 shown in an enlarged manner in FIG. 4, a double-sided print mode for forming an image on both sides of the recording medium is selected, or a paper feed button is pressed to select a special paper. By selecting or pressing the setting button, the paper feeder 15
Alternatively, the manual sheet feeding device 19 can be selected. Alternatively, a detailed image may be displayed on the display of the host computer 61, and an image forming process condition of an image to be output may be instructed in accordance with the detailed image. Information from the image forming apparatus can be displayed on a display.
The input for transmitting the characteristics of the recording medium to the image forming apparatus can be input from the keyboard with reference to the input image of the operation unit 51 or the host computer 61 or provided with a selection switch on the paper feed tray. Can be performed by operating a switch corresponding to. In addition, a paper tray for envelopes or a paper tray for postcards is prepared, and the tray is identified by setting the paper tray in the image forming apparatus main body.
The characteristics of the recording medium to be used can also be input. In this way, information handled by the host computer 61 can be printed according to the purpose and the type of recording medium.

The image forming system shown in FIG. 3 is a system connected by a so-called network, and the image forming apparatus mainly serves as an output device of the host computer 61. A system in which the image forming apparatus and the host computer are wirelessly connected without using a cable can also be used.

In the image forming apparatus shown in FIG. 11, as described above, the fixing device 20 moves the recording medium P in the conveying direction.
It is located downstream of the intermediate transfer member 3. The fixing device 20 includes a fixing roller 63 having a heater 62 therein.
And a pressure roller 64 pressed against the roller, and these rollers 63 and 64 are respectively driven to rotate in the direction of the arrow, and when the recording medium passes therebetween, the image transferred to this is fixed. Further, the intermediate transfer member 3 composed of the belt shown in FIG. 11 is also wound around a plurality of rollers 4, 5, 65 and driven in the direction of arrow A, but no heating means is provided on the back side thereof. Other configurations are the same as those of the image forming apparatus shown in FIGS. FIG. 12 shows that the intermediate transfer member 3 shown in FIG.
The state at the time of separation from A, 2 is shown.

The image forming apparatus for forming a single-color image on a recording medium has been described above. However, the above-described configurations can be applied to an image forming apparatus for forming a color image. FIG. 13 is a schematic sectional view showing one example. The image forming apparatus shown here has first and second image carriers 102 </ b> A and 102 formed of an intermediate transfer drum (which may be a belt) arranged so as to be able to contact and separate from the intermediate transfer body 3. The first and second photoconductors 202A and 202 are in contact with the image carriers 102A and 102, respectively. When the image forming operation is started, the first and second image carriers 10
2A and 102 are separated from the intermediate transfer member 3. The intermediate transfer member 3 is driven to rotate in the direction of arrow A, the first and second image carriers 102A and 102 are in the directions indicated by arrows B1 and B2, and the photoconductors 202A and 202 are indicated by arrows B11 and B12.
Are driven to rotate in the respective directions.

The second photosensitive member 202 is connected to the second charging device 1
07, the charged surface is exposed by the second exposure device 112 to form an electrostatic latent image on the surface of the image carrier. This electrostatic latent image is formed by the second developing device 108
The image is visualized as a toner image.
Are rotatably supported, and the yellow developing device 108
The developing device is configured as a revolver type developing device having a Y, magenta developing device 108M, a cyan developing device 108C, and a black developing device 108K. First, the yellow developing unit 108Y faces the second photoconductor 202, and visualizes the electrostatic latent image as a yellow toner image. This yellow image is transferred to the first image carrier 102 by the transfer unit 66.
The toner transferred onto the photoconductor 202 after the transfer is removed by the second cleaning device 109, and then the surface potential of the photoconductor is initialized by the second neutralization device 106.

Next, a magenta image is formed on the second photosensitive member 202 in the same manner as described above, except that the magenta developing device 108M opposed to the second photosensitive member 202 is used. The image is superimposed on the yellow image and transferred onto the image carrier 102. Next, a cyan image and a black image are sequentially formed on the photoconductor 202, and these are sequentially transferred onto the second image carrier 102 in a superimposed manner.

The first image composed of the color toner image transferred on the second image carrier 102 in this way is the second image.
Are collectively transferred onto the intermediate transfer member 3 by the transfer means 13 of the above. During this batch transfer, the second image carrier 102 contacts the intermediate transfer member 3 and the transfer residual toner is removed by the cleaning member 67 that contacts the second image carrier 102. When the toner image is being transferred from the photoconductor 202 to the image carrier 102, the cleaning member 67 is separated from the image carrier 102.

The charge polarity of the first image transferred onto the intermediate transfer member 3 is reversed by the charger 14.

The second photoconductor 202A is also surrounded by the second photoconductor 202A.
As in the case of the photoconductor 202, the first charging device 107
A, first exposure device 112A, yellow developing device 108Y
A, magenta developing device 108MA, cyan developing device 108C
A and a revolver-type first developing device 108A having a black developing device 108KA, a first cleaning device 109A, and a first static eliminator 106A are provided, respectively, in exactly the same manner as in the case of the second photoconductor 202,
Images composed of toners of different colors are sequentially formed on the first photosensitive member 202A, and these are sequentially transferred onto the first image carrier 102A by the transfer means 66A.

The recording medium P sent from the sheet feeding device 15 or the manual sheet feeding device 19 is sent between the first image carrier 102A and the intermediate transfer member 3. At this time, the first image carrier 102A comes into contact with the intermediate transfer member 3, and the first color image on the intermediate transfer member 3 and the first color image on the first image carrier 102A are moved by the first transfer means 13A. The two color images are respectively transferred to one surface and the other surface of the recording medium P. The transfer residual toner that adheres to the first image carrier 102A after the transfer is removed by the cleaning member 67A in contact with the image carrier 102A. The cleaning member 67A is also separated from the first image carrier 102A when the image of each color is transferred to the first image carrier 102A. The first and second images transferred to the recording medium are fixed by the fixing device 20. The recording medium that has passed through the fixing device 20 is discharged by a discharge stack 28 by a discharge roller pair 27.
Is discharged on top.

In the case of the example shown in FIG. 13, the first image carrier 102A, the first photoconductor 202A, and at least the photoconductor 202A and the first image carrier 102A are arranged around the first image carrier 102A. The first image forming unit 111A is constituted by one image forming means, and the second image carrier 1
02, a second photoconductor 202, and at least one photoconductor 202 disposed around the photoconductor 202 and the second image carrier 102.
A second image forming unit 111 is constituted by the two image forming means. Each of the image forming units 111A and 111 is slidably supported by each of the guide stays 52A and 52, and each of the exposure devices 112A and 112 slides on each of the guide rails 53A and 53 fixed to the guide stays 52A and 52. It is freely supported.

[0169] Structures other than the structure described above are shown in Figs.
There is no difference from the image forming apparatus shown in FIG. For example, the intermediate transfer member 3 and the first and second image forming units 111A, 111
When pulling out the intermediate transfer member 3,
Is rotated about the center of the swing, and the intermediate transfer body 3 is separated from the first and second image carriers 102A and 102 to form a gap between them. Elements in FIG. 13 corresponding to the elements shown in FIG. 2 are denoted by the same reference numerals as in FIG.

In the image forming apparatus shown in FIG.
Four first image carriers 302YA, 302MA, 302CA, 302K made of photoconductors are provided for the intermediate transfer body 3.
A is in contact therewith, and four second image carriers 302Y, 302M, 302C, 302 also made of photoconductors.
K abuts on each of the second image carriers 302Y, 302M, 302C, and 302K by image forming means (not shown) disposed around each of the second image carriers. , A first image of each color composed of cyan and black toners is formed, and these images are transferred onto the intermediate transfer member 3 in a superimposed manner. The charging polarity of the superimposed first image is reversed by the charger 14, and then the first image is fed to the sheet feeding device 15 or 19.
Is transferred to one surface of the recording medium fed from the printer. Further, each of the first image carriers 302YA, 302MA, 302
A second image of each color including yellow, magenta, cyan, and black toners is also formed on CA and 302KA, respectively, and these second images are superimposed and transferred to the other surface of the recording medium. You. The first and second images transferred to each side of the recording medium are
, And the recording medium is discharged onto the discharge stack unit 28.

In this example, four first image bearing members 302
YA, 302MA, 302CA, 302KA and at least one image forming means arranged around each of the image carriers form a first image forming unit 211A, and similarly four second image carriers 302Y. , 302M, 302
A second image forming unit 211 is constituted by C, 302K and at least one image forming means arranged around each image carrier. Other configurations are the same as those of the image forming apparatus shown in FIGS. Each element in FIG. 14 corresponding to each element shown in FIG. 2 is denoted by the same reference numeral as in FIG. As in this example, a plurality of first and second image carriers may be provided.

Also, in the case of the image forming apparatus shown in FIGS. 13 and 14, the fixing device 20 can be provided separately from the intermediate transfer member 3 as in the case of FIG. It is also possible to form an image only on the surface.

The present invention can be widely applied not only to a printer but also to an image forming apparatus such as an electronic copying machine, a facsimile, a printing machine, or a multifunction peripheral thereof, and an image forming system having the image forming apparatus. .

[0174]

According to the first aspect of the present invention, it is possible to form a double-sided image at a high speed by mounting the second image carrier as needed.

According to the second aspect of the present invention, when the second image carrier is mounted, the image forming mode is manually changed to the second image carrier.
There is no need to switch to the mode.

According to the third and fifth aspects of the present invention, an image can be formed only on one side of the intermediate transfer member.

According to the fourth aspect of the invention, the image forming operation can be continued even when the toner for forming an image on the second image carrier runs out.

According to the sixth aspect of the present invention, the image forming operation can be continued even when the toner for forming an image on the first image carrier runs out.

According to the seventh aspect of the present invention, an image can be formed on both sides of a recording medium by forming an image only on the first image carrier without forming an image on the second image carrier. Can be formed.

According to the eighth aspect of the present invention, an image can be formed on both sides of a recording medium even when the toner for forming an image on the second image carrier runs out.

According to the ninth aspect, the types of components of the image forming apparatus can be reduced.

According to the tenth and eleventh aspects,
The first and second image forming units can be easily attached to and detached from the image forming apparatus main body.

According to the twelfth and thirteenth aspects,
It is possible to eliminate mounting errors of the image forming unit.

According to the fourteenth aspect of the invention, it is possible to prevent the image quality from deteriorating due to the contact and separation of the cleaning member with respect to the intermediate transfer member.

According to the invention of claims 15 to 17,
By the common transfer means, the first image on the intermediate transfer member and the second image on the first image carrier can be transferred to one surface and the other surface of the same recording medium.

According to the eighteenth aspect, it is possible to prevent a problem that an image before being fixed by the fixing device is disturbed.

According to the nineteenth aspect, it is possible to prevent the image quality from deteriorating due to the contact and separation of the fixing member with respect to the intermediate transfer member.

According to the twentieth aspect, the intermediate transfer member heated by the fixing device can be cooled.

According to the twenty-first aspect, an operation error can be prevented from occurring.

According to the twenty-second aspect, the operability of the image forming apparatus can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating an example of an image forming apparatus.

FIG. 2 is a schematic sectional view illustrating a state when a second image carrier is added to the image forming apparatus illustrated in FIG. 1;

FIG. 3 is an external perspective view of an image forming apparatus and a host computer.

FIG. 4 is an enlarged view of an operation unit.

FIG. 5 is a perspective view showing a state where the front door is opened and the intermediate unit and the image forming unit are taken out of the image forming apparatus main body.

FIG. 6 is a schematic side sectional view showing an intermediate unit set in the image forming apparatus main body.

FIG. 7 is a schematic sectional view when the intermediate transfer body shown in FIG. 2 is separated from first and second image carriers.

FIG. 8 is a diagram illustrating a positional relationship between first and second image carriers and a support shaft.

FIG. 9 is a schematic front view showing a state of the intermediate unit and first and second image forming units when the front door is opened.

FIG. 10 is a schematic front view when the intermediate unit shown in FIG. 9 is rotated.

FIG. 11 is a schematic sectional view showing another example of the image forming apparatus.

FIG. 12 is a schematic cross-sectional view when the intermediate transfer member of the image forming apparatus shown in FIG. 11 is separated from first and second image carriers.

FIG. 13 is a schematic sectional view showing still another example of the image forming apparatus.

FIG. 14 is a schematic sectional view showing still another example of the image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body 2 2nd image carrier 2A 1st image carrier 3 Intermediate transfer body 11 2nd image forming unit 11A 1st image forming unit 13A Transfer means 20 Fixing device 29 Cleaning device 33 Cooling means 102 Second image carrier 102A First image carrier 111 Second image forming unit 111A First image forming unit 211 Second image forming unit 211A First image forming unit 302Y Second image carrier 302M 2nd image carrier 302C 2nd image carrier 302K 2nd image carrier 302YA 1st image carrier 302MA 1st image carrier 302CA 1st image carrier 302KA 1st image carrier P Recording medium

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/18 G03G 15/16 2H072 15/16 15/20 101 3F049 15/20 101 15/00 556 21 / 20 21/00 534 F-term (reference) 2H027 DA11 DA27 DD02 EC14 ED01 ED10 EE07 EF01 FA13 FA35 FA37 GA47 HB13 HB14 JA11 JB16 JB20 JC03 JC14 2H028 BA14 BB02 BC01 2H032 AA05 AA15 BA09 BA19 BA23 BA30 BA02 BA12 2H071 BA03 BA04 BA13 BA19 BA20 BA33 DA05 DA09 DA12 DA15 DA32 EA04 2H072 AB07 CA07 JA03 3F049 AA10 BA00 LA02 LA05 LA07 LB03

Claims (22)

[Claims] 1. An image carrier on which an image is formed, and an intermediate transfer member on which the image formed on the image carrier is transferred, wherein the image transferred to the intermediate transfer member is transferred to one side of a recording medium. An image forming apparatus that transfers a next image formed on the image carrier to the other surface of the recording medium to obtain a recorded image, wherein the image carrier is a first image carrier When the image forming mode is the first mode, an image carrier mounting portion for mounting a second image carrier different from the first image carrier on the image forming apparatus main body is provided. When the second image carrier is mounted, an image formed on the second image carrier is transferred to the intermediate transfer member, and the transferred image is transferred to one surface of a recording medium. An image formed on the first image carrier is transferred to the other surface of the recording medium to obtain a recorded image An image forming apparatus characterized by being configured so as to perform image formation in the second mode. 2. The image forming apparatus according to claim 1, further comprising: mode switching means for automatically switching an image forming mode to the second mode when the second image carrier is mounted on the image forming apparatus main body. The image forming apparatus as described in the above. 3. The image forming apparatus according to claim 1, wherein a third mode in which only an image formed on the first image carrier is transferred to a recording medium is selectable. 4. When the toner for forming an image on the second image carrier runs out by performing the image forming operation by mounting the second image carrier on the main body of the image forming apparatus, The image forming apparatus according to claim 3, wherein the third mode is selected. 5. The image processing apparatus according to claim 1, wherein an image formed on the second image carrier is transferred to an intermediate transfer member, and a fourth mode for transferring only the image to a recording medium is selectable. An image forming apparatus according to any one of the above. 6. The image forming apparatus according to claim 5, wherein the fourth mode is selected when the toner for forming an image on the first image carrier runs out. 7. When the second image bearing member is mounted,
7. The apparatus according to claim 1, wherein said first mode is selectable.
The image forming apparatus according to any one of the above. 8. The image forming apparatus according to claim 7, wherein the first mode can be selected when toner for forming an image on the second image carrier runs out. 9. The image according to claim 1, wherein the first image carrier and the second image carrier are formed in substantially the same shape and substantially the same size. Forming equipment. 10. The first image carrier and at least one image forming means for forming an image on the first image carrier are configured as a first image forming unit, and The image carrier and at least one image forming unit for forming an image on the second image carrier are configured as a second image forming unit, and the first and second image forming units are formed. The image forming apparatus is configured to be attached to and detached from an image forming apparatus main body from the same surface side, and a second image forming unit is mounted on the image carrier mounting section. Image forming apparatus. 11. The first and second image forming units include:
The image forming apparatus according to claim 10, wherein the image forming apparatus is configured to be attached to and detached from a main operation surface side of the image forming apparatus main body. 12. The first image carrier and at least one image forming means for forming an image on the first image carrier are configured as a first image forming unit, and The image carrier and at least one image forming unit for forming an image on the second image carrier are configured as a second image forming unit, and the first image forming unit and the second image forming unit The first image forming unit and the second image forming unit are configured so that one of the image forming units can be mounted at a mounting position of the other image forming unit.
2. The image forming apparatus according to claim 1, 13. The image forming apparatus according to claim 12, wherein the first image forming unit and the second image forming unit have substantially the same size and substantially the same shape. 14. A cleaning device for an intermediate transfer member, comprising: a cleaning member for removing a transfer residual toner attached to the intermediate transfer member after transferring an image on the intermediate transfer member to a recording medium; 14. The image forming apparatus according to claim 1, wherein the cleaning member is configured to be in constant contact with the intermediate transfer member when the second image carrier is mounted on the image forming apparatus main body. 15. An image transferred from the second image bearing member to an intermediate transfer member and an image formed on the first image bearing member,
The image forming apparatus according to claim 1, further comprising a transfer unit that simultaneously transfers the data to one surface and the other surface of the recording medium. 16. The image forming apparatus according to claim 1, wherein the transfer unit is configured to transfer an image on the intermediate transfer member charged to a first polarity and an image on a first image carrier charged to a second polarity opposite to the first polarity. 16. The image forming apparatus according to claim 15, wherein the image forming apparatus is configured to transfer the image onto one surface and the other surface of the recording medium. 17. An image charged to the second polarity is formed on each of the first and second image carriers, and the charge polarity of the image transferred to the intermediate transfer member is converted to the first polarity. The image forming apparatus according to claim 16, further comprising a polarity conversion unit that causes the polarity to be changed. 18. The image forming apparatus according to claim 1, further comprising a fixing device arranged to fix an image transferred to a recording medium superimposed on the intermediate transfer body. 19. The image forming apparatus according to claim 19, wherein the fixing device has a fixing member for fixing an image by contacting the recording medium superimposed on the intermediate transfer member. 19. The image forming apparatus according to claim 18, wherein the fixing member is configured to always contact the intermediate transfer member directly or via a recording medium. 20. The fixing device according to claim 1, wherein the fixing device is configured to fix the image onto the recording medium at least by the action of heat, and the moving direction of the surface of the intermediate transfer member is downstream of the fixing position where the fixing is performed. 20. A cooling means for cooling an intermediate transfer member upstream of a transfer position where an image is transferred from the second image carrier to the intermediate transfer member.
4. The image forming apparatus according to claim 1. 21. A display that indicates that the second image carrier is attached to the image forming apparatus main body, and a display unit of the image forming apparatus itself and at least a host device connected to the image forming apparatus. 21. The image forming apparatus according to claim 1, wherein the image is displayed on one side. 22. An image forming system comprising the image forming apparatus according to claim 1 and a host device.