JP4079744B2 - Simultaneous double-sided image forming device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a first image formed by an image forming device is transferred to and supported on a primary image carrying device, and the first image is transferred to a secondary image carrying device, and then separately formed by the image forming device. The present invention relates to a simultaneous double-sided image forming apparatus that transfers a first image and a second image onto both sides of a recording medium after the second image is transferred and supported on a primary image carrier.
[0002]
[Prior art]
As a conventional double-sided image forming apparatus, after the first image formed by the image forming device is transferred to one surface of the recording medium, the recording medium is reversed by the reversing device, and then separately by the image forming device. Some transfer the formed second image to the other surface of the recording medium.
[0003]
However, in such a double-sided image forming apparatus, after the first image is transferred to one side of the recording medium, the recording medium is reversed by the reversing device, and therefore it takes time to transfer the image to both sides of the recording medium. There was a problem. Therefore, the following simultaneous double-sided image forming apparatus capable of forming images on both sides of a recording medium almost simultaneously has been proposed.
[0004]
[Patent Document 1]
JP 2000-352889 A
This simultaneous double-sided image forming apparatus has image forming devices on both sides of the recording medium that passes through the apparatus, forms separate images with these image forming devices, and transfers the images to both sides of the recording medium almost simultaneously. To do.
[0006]
However, in such a simultaneous double-sided image forming apparatus, since the image forming apparatuses are provided on both sides of the recording medium, there is a problem that the apparatus becomes large. Therefore, the following simultaneous double-sided image forming apparatus has been proposed.
[0007]
[Patent Document 2]
Japanese Patent Laid-Open No. 2000-293065
In this simultaneous double-sided image forming apparatus, toner images are formed on four image forming carriers by four developing units of yellow, magenta, cyan, and black, respectively, and the first image is formed on the image supporting member by a transfer unit. After the first image is formed by transfer, a toner image is separately formed on each image forming carrier. Then, the first image carried on the image carrier is transferred onto the surface of the recording medium conveyed by the medium carrier device, and the four color toner images formed on the four image carriers are transferred. Then, a second image is formed on the back surface, and images are formed on both surfaces of the recording medium.
[0009]
However, in such a simultaneous double-sided image forming apparatus, since the second image is transferred by the contact of the four image forming carriers on the back surface of the recording medium, the image is imaged when dust or the like adheres to the recording medium. There is a problem that the dust adheres to the image forming carrier by the transfer of the image, and an unclear image is formed in the subsequent image forming. Therefore, a simultaneous double-sided image forming apparatus as shown in FIG. 4 has been proposed.
[0010]
This simultaneous double-sided image forming apparatus includes an image forming device 2 and a primary image carrying device 3 in a main part 1 of the apparatus main body, and a secondary image carrying device 5 in a sub body part 4 of the apparatus main body. Further, a first bias control substrate 8 is provided in the primary image carrier 6 of the primary image carrier 3, and a second bias control substrate is provided in the secondary image carrier 7 of the secondary image carrier 5. 9 is provided. Further, the sub body portion 4 can be opened and closed with respect to the main body portion 1.
[0011]
Then, the first image formed by the image forming device 2 is transferred and supported on the primary image carrier device 3 by applying a first bias voltage to the primary transfer means 2a by the first bias control substrate 8 and the first image is carried. The second bias control substrate 9 applies a second bias voltage to the secondary transfer means 5a to transfer the image to the secondary image carrier device 5, and then the second image separately formed by the image forming device 2 is transferred to the second image transfer device 5a. A first bias voltage is applied by the first bias control substrate 8 to be transferred to and supported by the primary image carrier 3, and then the recording medium is passed between the primary image carrier 6 and the secondary image carrier 7 through the first medium. And the second image are transferred to both sides of the recording medium almost simultaneously.
[0012]
[Problems to be solved by the invention]
However, in such a simultaneous double-sided image forming apparatus, when the secondary image carrier 7 is taken out, the second bias control substrate 9 provided therein must also be taken out. For this reason, it is necessary to once disconnect the electrical connection of the second bias control substrate 9, and there is a problem that it is difficult to take out the secondary image carrier 7.
[0013]
Therefore, a first object of the present invention is to easily attach and detach the secondary image carrier.
[0014]
A second object of the present invention is to provide a simultaneous double-sided image forming apparatus having a simple configuration.
[0015]
A third object of the present invention is to reduce the size of the simultaneous double-sided image forming apparatus.
[0016]
A fourth object of the present invention is to provide an inexpensive simultaneous double-sided image forming apparatus.
[0017]
A fifth object of the present invention is to reliably perform transfer.
[0018]
[Means for Solving the Problems]
Therefore, in order to achieve the above first , third , and fourth objects, the invention described in claim 1 includes an image forming device that forms an image on the image forming carrier, and an image on the image forming carrier. A primary image carrying device that is transferred by an image forming transfer means and carried on a primary image carrier, and a secondary that carries an image carried by the primary image carrier by a primary transfer means and is carried on the secondary image carrier. An image carrying device, and a medium carrying device that carries the recording medium between the primary image carrying device and the secondary image carrying device, and the primary image carrying member on both sides of the recording medium carried by the medium carrying device. The second image carried thereon is transferred by the primary transfer unit, and the first image carried on the secondary image carrier is transferred by the secondary transfer unit, so that images are simultaneously formed on both sides of the recording medium. In the simultaneous double-sided image forming apparatus for forming
The primary transfer means has a transfer member provided on the primary image carrier side, and the bias control substrate controls the application of a bias voltage to the transfer member ;
An image forming apparatus main body is composed of a main part and a sub-body part that is openable and closable with respect to the main part, and includes the image forming device, the primary image carrier device, and the bias control substrate on the main part side, The secondary image carrying device is provided on the sub body side,
The primary image carrier is formed into an endless belt, and the bias control substrate is disposed in the endless belt-shaped primary image carrier to be wound around,
The application of a bias voltage to the image forming transfer unit is also controlled by the bias control substrate.
[0019]
According to a second aspect of the present invention, in order to achieve the second object described above, in the simultaneous double-sided image forming apparatus according to the first aspect, the primary image carrier has an endless belt shape, and the endless belt-shaped primary is provided. One of the primary rollers around which the image carrier is wound is also used as the transfer member.
[0023]
According to a third aspect of the invention, to achieve the fourth object described above, another is in the simultaneous double-sided image forming apparatus according to claim 1, and the bias control board to the primary image bearing body of the endless belt The bias control substrate is arranged separately, and the application of the bias voltage to the image forming transfer means is controlled by the separate bias control substrate.
[0024]
According to a fourth aspect of the present invention, in order to achieve the fifth object described above, in the simultaneous double-sided image forming apparatus according to any one of the first to third aspects, the secondary image carrier is provided in the primary transfer unit. A backing member is grounded so as to face the transfer member across a body.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an overall schematic configuration of a simultaneous double-sided image forming printer which is an example of the present invention.
[0026]
The simultaneous double-sided image forming printer shown in FIG. 1 enables image formation on both front and back sides of a recording medium P such as paper / OHP film almost simultaneously. As shown in FIG. Four image forming devices A, B, C, and D, a primary image carrier device E, a secondary image carrier device F, a medium transport device G, a fixing device H, a discharge stack device I, a toner supply device J, and the like are provided. .
[0027]
The four image forming apparatuses A, B, C, and D form different monochrome images using toners of yellow, magenta, cyan, and black, respectively, and are drum-shaped images that are rotatably supported. Supporting bodies 12 are arranged in a tandem manner, and charging means 13, developing means 14, image forming transfer means 15, image forming cleaning means 16, and image forming charge eliminating means 17 are arranged around each image forming support body 12. Yes. Under these image forming apparatuses A, B, C, and D, common exposure means 18 for exposing the individual image forming carriers 12 to each other is provided.
[0028]
The image forming carrier 12 is a photoreceptor in which an organic semiconductor layer that is a photoconductive substance is provided on the surface of an aluminum cylinder having a diameter of about 30 to 100 mm. In this example, a drum-like one is used, but a belt-like one may be used.
[0029]
The exposure unit 18 irradiates light from an LD light source (not shown) toward the surface of the image carrier 12 by an optical component (not shown) by a known laser method, and scans the surface of the image carrier 12. To write to it. In this example, a laser method is used, but an exposure method using an LED array and an imaging component may be adopted.
[0030]
The primary image carrying device E transfers and carries the images formed by the respective image forming devices A, B, C, and D. The primary image carrying device 20 supports the primary image carrier 20 in the form of an endless belt. The image forming carrier 12 and the image forming transfer means 15 corresponding to the image forming carrier 12 and the three image forming transfer means 15. The abutting member 25 is arranged. In this example, the backing roller 25 and the primary roller (transfer member) 22 constitute a primary transfer means 26.
[0031]
The primary image carrier 20 is a belt based on a resin film or rubber having a thickness of 50 μm to 600 μm, and has a resistance value that allows toner to be transferred from each image forming carrier 12.
[0032]
The secondary image carrier device F is to primarily transfer and carry the image carried by the primary image carrier device E. The secondary image carrier device 30 is brought into contact with the primary image carrier member 20 in contact with the secondary image carrier member 30. A predetermined transfer nip is formed between the primary image carrier 20 and the backing roller 25, and is wound around three secondary rollers 32, 33, and 34. Transfer means 36 is arranged.
[0033]
Similar to the primary image carrier 20, the secondary image carrier 30 is a belt based on a resin film or rubber having a thickness of 50 μm to 600 μm, and has a resistance value that enables transfer of toner from the primary image carrier 20. Have.
[0034]
The medium conveyance device G conveys the recording medium P through a medium conveyance path that passes between the primary image carrying device E and the secondary image carrying device F and extends from the lower side to the upper side in the drawing, and is provided in two upper and lower stages. A medium storage container 40 for storing the recording medium P, a supply roller 41 for sequentially feeding the recording medium P from the medium storage container 40 one by one from the top, and a medium guide for guiding the sent recording medium P. 42, a registration roller 43 that abuts and stops the leading end of the recording medium P guided and conveyed by the medium guide 42, a discharge guide 44 that guides the recording medium P after image fixing, and a guide that is guided by the discharge guide 44. And a discharge roller 45 for discharging the recording medium P to be conveyed in the direction of arrow a.
[0035]
The fixing device H fixes a transfer image transferred from the primary image carrying device E and the secondary image carrying device F to the recording medium P, and includes a pair of heating rollers 47.
[0036]
The discharge stack apparatus I stacks the recording medium P after image fixing by the fixing apparatus H, and includes a stack unit 50 formed on the image forming apparatus main body 10.
[0037]
The toner replenishing device J replenishes each image forming device A, B, C, and D with a new toner using a powder pump or the like, and includes a toner cartridge 53 for each color in the toner storage portion 52.
[0038]
When the simultaneous double-sided image forming printer forms color images on both the front and back sides of the recording medium P, the image forming carrier 12 and the primary rollers 21, 22, and 23 are controlled based on a print signal from a host (not shown). One of the secondary rollers 32, 33, and 34, the supply roller 41, and the like are rotated in time.
[0039]
In each of the image forming apparatuses A, B, C, and D, as each image forming carrier 12 rotates in the clockwise direction in the figure, the surface is uniformly charged by each charging means 13, and the common exposure means is used. Writing is performed with individual writing light from 18 to form a latent image for each color, and a toner image for each color is formed on each image forming carrier 12 by attaching each color toner by each developing means 14. To do. In the illustrated example, the charging polarity of the toner on the image forming carrier 12 is negative.
[0040]
In the primary image carrier E, one of the primary rollers 21, 22, and 23 is rotated and the other two primary rollers are driven to rotate, so that the primary image carrier 20 is synchronized with the image carrier 12 in the figure. The toner images on the image carrier 12 are sequentially transferred to the primary image carrier 20 by the respective image transfer means 15 and are sequentially transferred to the primary image carrier 20 so as to superimpose four colors. Image).
[0041]
After the image transfer, the image forming carrier 12 of each of the image forming apparatuses A, B, C, and D removes the residual toner by the image forming cleaning unit 16 and discharges the image by the image forming and discharging unit 17. Thereafter, charging is performed again by each charging unit 13, writing is performed by the exposure unit 18, development is performed by each developing unit 14, and a toner image for each color is formed again on each image forming carrier 12.
[0042]
In the secondary image carrier F, the secondary image carrier 30 is rotated in synchronization with the primary image carrier 20 by rotating one of the secondary rollers 32, 33, 34 and the other secondary roller following the rotation. The toner image carried on the primary image carrier 20 is transferred to the secondary image carrier 30 by the primary transfer means 26 composed of the primary roller 22 and the backing roller 25.
[0043]
At this time, the secondary cleaning unit 35 is in a non-cleaning state in which the secondary cleaning unit 35 is rotated about the support shaft 56 and separated from the secondary image carrier 30.
[0044]
After the image transfer, the primary image carrier 20 of the primary image carrier E removes residual toner by the primary cleaning unit 24. Thereafter, the images on the image carrier 12 are sequentially transferred onto the primary image carrier 20 by the respective image transfer means 15 to form a second full-color image (second image) in which four colors are superimposed. To do.
[0045]
After the image transfer, the image forming carrier 12 of each of the image forming apparatuses A, B, C, and D removes the residual toner by the image forming cleaning unit 16 and discharges the image by the image forming and discharging unit 17 to perform the next image forming cycle. Prepare for.
[0046]
On the other hand, in the medium transport apparatus G, one of the supply rollers 41 is selectively rotated as appropriate to feed the recording medium P in the medium storage container 40, guided by the medium guide 42 in the medium transport path, and the leading end of the registration roller 43 The registration roller 43 is rotated in synchronization with the first full color image and the second full color image, and the transfer nip between the primary image carrier 20 and the secondary image carrier 30 is stopped. To send.
[0047]
Then, the second full-color image carried on the primary image carrier 20 is transferred by the primary transfer means 26, and the first full-color image carried on the secondary carrier 30 is transferred by the secondary transfer means 36. After the images are transferred to both the front and back surfaces, the recording medium P is guided to the fixing device H, and heat and pressure are applied through a pair of heating rollers 47 to fix the transferred images on both sides. In 45, the sheet is discharged out of the image forming apparatus main body 10 and stacked face down on the stack unit 50 of the discharge stack apparatus I with the surface down.
[0048]
Therefore, the second page is formed first as the first full-color image, the first page is formed later as the second full-color image, and the subsequent page is formed first in the same manner, so that the recording medium P The recording medium P can be arranged in the page order on the stack unit 50 by transferring to the back side of the sheet, forming the previous page later, transferring it to the front side, and outputting it face down.
[0049]
At this time, by using a known image processing technique, the second full-color image on the primary image carrier 20 is a normal image on the image carrier 12 and the first full-color image on the secondary image carrier 30. Needs to be a reverse image or a mirror image on the image forming carrier 12.
[0050]
After the image transfer, the primary image carrier 20 of the primary image carrier E removes residual toner by the primary cleaning unit 24. In addition, the secondary image carrier 30 of the secondary image carrier F is previously cleaned by rotating the secondary cleaning means 35 around the support shaft 56 to contact the secondary image carrier 30. The residual toner is removed by the secondary cleaning means 35 to prepare for the next image bearing.
[0051]
When the toner of each developing means 14 is used up, the toner of the same color is replenished by being conveyed from the corresponding toner cartridge 53 of the toner storage portion 52 of the toner replenishing device J by a powder pump or the like.
[0052]
The image forming apparatus main body 10 is composed of a main body portion 10A and a sub body portion 10B that can be opened and closed with respect to the main body portion 10A. The portion 10B is opened in the direction of the arrow d with the support shaft 55 as the center, and the medium conveyance path extending between the primary image carrier device E and the secondary image carrier device F is opened to perform jam processing.
[0053]
When a full-color image is formed on one side of the recording medium P with this simultaneous double-sided image forming printer, the images formed on the respective image forming bodies 12 of the image forming apparatuses A, B, C, and D are used as the primary image holding apparatus E. After the image is transferred to the primary image carrier 20, the image is sequentially transferred directly to one side of the recording medium P conveyed by the medium conveyance device G without being transferred to the secondary image carrier 30 of the secondary image carrier F. To do. Then, the transferred image is fixed by the fixing device H, and discharged to the discharge stack device I in the page order in a face-down manner.
[0054]
In addition, when a two-color image or a monochrome image is formed on the recording medium P with the illustrated printer, the image is formed by using the corresponding color image forming device among the four image forming devices A, B, C, and D. Then, the image is transferred to the recording medium P via the primary image carrier 20 of the primary image carrier E and the secondary image carrier 30 of the secondary image carrier F.
[0055]
By the way, as shown in FIG. 2, the image forming apparatus main body 10 of the simultaneous double-sided image forming apparatus includes four image forming apparatuses A, B, C, and D, a primary image carrying apparatus E, and the like. The secondary body 10B is provided on the side of the secondary body 10B of the image forming apparatus main body 10, and the secondary body 10B can be opened and closed with respect to the main body 10A.
[0056]
An endless belt-shaped primary image carrier 20 in the main body 10A is wound around the image forming transfer means 15 of the image forming apparatuses A, B, C, and D. A first bias control board (another bias control board) 60 for controlling the application of the first bias voltage, and a second bias voltage having the same negative polarity as the toner polarity for the primary roller 22. A second bias control board (bias control board) 61 is provided separately.
[0057]
The first bias control board 60 is electrically connected to the image forming transfer means 15 of the image forming apparatuses A, B, C, and D. On the other hand, the second bias control means 61 is electrically connected to the primary roller 22. Further, the first bias control board 60 and the second bias control board 61 are each connected to a control board (not shown) that controls the entire simultaneous double-sided image forming apparatus. In this example, the primary roller 22 and the backing roller 25 are provided opposite to each other with the secondary image carrier 30 interposed therebetween, and the primary roller 22 is provided on the primary image carrier 20 side. 25 is grounded to the secondary image carrier 30 side.
[0058]
In order to form images on both sides of the recording medium P using the primary image carrier 20 configured as described above, a positive first bias voltage is applied to the image forming transfer unit 15 by the first bias control substrate 60. Then, the first full color image having negative polarity formed by the image forming apparatuses A, B, C, and D is transferred by being attracted to the primary image carrier 20 of the primary image carrier E. The primary image carrier 20 rotates in the direction of the arrow b while carrying this image.
[0059]
After that, when the leading edge of the first full-color image reaches the first transfer position Tr1, a negative second bias voltage is applied to the primary roller 22 by the second bias control substrate 61 and is carried on the primary image carrier 20. A first full-color image having a negative polarity is transferred from the primary image carrier 20 to the surface of the secondary image carrier 30 that rotates in the direction of arrow c. At this time, since the backing roller 25 in contact with the back surface of the secondary image carrier 30 is grounded, the first full-color image having a negative polarity can be easily attracted and the transfer can be reliably performed.
[0060]
That is, since the primary roller 22 also serves as a transfer member for transferring the image on the primary image carrier 20 onto the secondary image carrier 30, there is no need to provide a separate transfer member, and the number of parts is reduced. Thus, the apparatus can be made compact. Further, the secondary transfer device F does not require electrical connection, and the structure on the secondary transfer device F side can be simplified.
[0061]
Thereafter, a positive first bias voltage is applied from the image forming transfer means 15 to the negative full-color second full-color image separately formed by the image forming apparatuses A, B, C, and D by the first bias control substrate 60, and the primary The image is transferred by being attracted to the image carrier 20.
[0062]
The recording medium P is transported to the first transfer position Tr1 between the primary image carrier 20 and the secondary image carrier 30 in accordance with the timing of the first full color image and the second full color image, and the second bias. When a negative second bias voltage is applied to the primary roller 22 by the control substrate 61, the negative full-color second full-color image carried on the primary image carrier 20 is repelled from the primary image carrier 20 and is recorded on the recording medium P. Transferred to the surface. Further, by applying a positive bias voltage to the secondary transfer means 36 at the second transfer position Tr2, and attracting the first full-color image carried on the secondary image carrier 30 to the back surface of the recording medium P. After the transfer, the image is conveyed to the fixing device H.
[0063]
When the secondary image carrier 30 is removed, the secondary body 10B of the image forming apparatus main body 10 shown in FIG. 1 is opened around the support shaft 55 in the direction of the arrow d, the secondary image carrier 30 is removed, and a new secondary image carrier 30 is removed. After attaching the next image carrier, the sub body portion 10B is closed. At this time, since the secondary image carrier 30 is not provided with an electrical component such as the second bias control board 61, the secondary image carrier 30 can be easily attached without disconnecting the electrical connection of the connection connector or the like. It can be removed and a new secondary image carrier 30 can be attached.
[0064]
In the above-described example, the first bias control substrate 60 and the second bias control substrate 61 are provided separately in the endless belt-shaped primary image carrier 20 that is wound around, but the present invention is not limited to this. Instead, as shown in FIG. 3, the second bias control substrate 61 controls the application of the second bias voltage to the first transfer unit 26 and also controls the application of the first bias voltage to the image forming transfer unit 15. You may do it.
[0065]
In the above-described example, the first bias control substrate 60 and the second bias control substrate 61 are provided in the primary image carrier 20, but the present invention is not limited to this, and is provided in the main portion 10A. Just do it.
[0066]
Furthermore, in the above-mentioned example, the example of the printer that forms a full-color image on both sides simultaneously has been described. However, the present invention is not limited to this, and a printer that forms a monochrome image on both sides simultaneously or forms an image on one side. It can also be applied to a printer. Further, the present invention is not limited to a printer, and can be applied to any image forming apparatus such as a facsimile or a copying machine.
[0067]
【The invention's effect】
As described above, according to the first aspect of the present invention, the primary transfer unit has the transfer member provided on the primary image carrier side, and the bias voltage applied to the transfer member is controlled by the bias control substrate. A bias control board that controls the application of a bias voltage to the transfer member can be provided on the image carrier device side, and there is no need to provide a connection connector on the secondary image carrier device side for attaching / detaching the secondary image carrier. The secondary image carrier can be easily attached and detached.
[0068]
According to the second aspect of the present invention, the primary image carrier is formed in an endless belt shape, and one of the primary rollers that wrap around the endless belt-shaped primary image carrier is also used as a transfer member. There is no need to provide a member, and it is possible to provide a simultaneous double-sided image forming apparatus having a simple configuration by reducing the number of parts.
[0069]
According to the first aspect of the present invention, the image forming apparatus main body is composed of a main part and a sub-body part that can be opened and closed with respect to the main part, and the image forming device, the primary image carrying device, and the bias control substrate, Is provided on the main body side, and the secondary image carrier device is provided on the secondary body side, so that a bias control substrate for controlling the application of the bias voltage to the transfer member is provided on the secondary body side to be opened and closed, or the secondary image carrier is provided. It is not necessary to provide a connector for cutting and connecting when the body is attached and detached, and the secondary image carrier can be easily attached and detached.
[0070]
According to the invention described in claim 1, the primary image bearing member and an endless belt shape, so place the endless belt of the bias control board to the primary image bearing body to turn over, effectively the space of the primary image bearing body By utilizing this, the simultaneous double-sided image forming apparatus can be reduced in size.
[0071]
According to the first aspect of the present invention, since the application of the bias voltage to the image forming transfer unit is also controlled by the bias control substrate, an inexpensive simultaneous double-sided image forming apparatus is provided without providing a separate bias control substrate. be able to.
[0072]
According to the third aspect of the present invention, the bias control substrate different from the bias control substrate is disposed separately in the endless belt-shaped primary image carrier, and the bias for the image transfer means is provided by the separate bias control substrate. Since the application of voltage is controlled, when replacing either the bias control board or another bias control board, only the necessary one can be replaced, and an inexpensive simultaneous duplex image forming apparatus is provided. be able to.
[0073]
According to the fourth aspect of the invention, since the primary transfer means is provided with the backing member grounded so as to face the transfer member with the secondary image carrier interposed therebetween, the primary image carrier to the secondary image carrier. The transfer to can be performed reliably.
[Brief description of the drawings]
FIG. 1 is a simultaneous double-sided image forming printer as an example of a simultaneous double-sided image forming apparatus of the present invention, and is an overall schematic configuration diagram of its internal mechanism.
FIG. 2 is a partially enlarged view thereof.
FIG. 3 is a partially enlarged view of another example.
FIG. 4 is a schematic configuration diagram of a main part of a conventional simultaneous double-sided image forming apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Image forming apparatus main body 10A Main part 10B Sub-body part 12 Image formation carrier 15 Image formation transfer means 20 Primary image carrier 22 Primary roller (transfer member)
25 Backing roller (backing member)
26 Primary transfer means 30 Secondary image carrier 36 Secondary transfer means 60 First bias control substrate (separate bias control substrate)
61 Second bias control board (bias control board)
A, B, C, D Image forming device E Primary image carrier device F Secondary image carrier device G Medium transport device P Recording medium

Claims (4)

An image forming device for forming an image on the image forming carrier, a primary image carrying device for transferring the image on the image forming carrier by an image forming transfer means and supporting the image on the primary image supporting member, and the primary image holding device A secondary image carrying device for transferring an image carried on the body by a primary transfer means and carrying the image on the secondary image carrying member, and a medium conveyed through the recording medium between the primary image carrying device and the secondary image carrying device A transport device,
The second image carried on the primary image carrier is transferred to the front and back of the recording medium carried by the medium carrying device by the primary transfer means, and the first image carried on the secondary image carrier. In a simultaneous double-sided image forming apparatus for transferring images by secondary transfer means and simultaneously forming images on both sides of the recording medium,
The primary transfer means has a transfer member provided on the primary image carrier side, and the bias control substrate controls the application of a bias voltage to the transfer member ;
An image forming apparatus main body is composed of a main part and a sub-body part that is openable and closable with respect to the main part, and includes the image forming device, the primary image carrier device, and the bias control substrate on the main part side, The secondary image carrying device is provided on the sub body side,
The primary image carrier is formed into an endless belt, and the bias control substrate is disposed in the endless belt-shaped primary image carrier to be wound around,
The simultaneous double-sided image forming apparatus , wherein application of a bias voltage to the image forming transfer unit is also controlled by the bias control substrate . 2. The simultaneous double-sided surface according to claim 1, wherein the primary image carrier has an endless belt shape, and one of the primary rollers that wrap around the endless belt-like primary image carrier is also used as the transfer member. Image forming apparatus. A bias control substrate different from the bias control substrate is disposed separately in the endless belt-shaped primary image carrier, and application of a bias voltage to the image transfer means is controlled by the separate bias control substrate. The simultaneous double-sided image forming apparatus according to claim 1 , wherein the apparatus is characterized in that: Said primary transfer means, the opposite to the transfer member across the secondary image bearing member, characterized in that it comprises by grounding the backing member, simultaneous double-side according to any one of claims 1 to 3 Image forming apparatus.

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