JP2008281933A - Transfer device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transfer device capable of suppressing occurrence of image deterioration caused by transitional load variation without disturbing images on an intermediate transfer body during the passage of transfer paper sheets through a secondary transfer nip, and to provide an image forming apparatus with the transfer device. <P>SOLUTION: A tension adjusting means, which abuts on the rear surface being the internal face of a loop, of the intermediate transfer belt 10 upstream and downstream of the transfer nip in the rotating direction of the intermediate transfer belt, adjust the tension of the intermediate transfer belt 10 according to a change in the tension of the belt 10, thereby suppressing occurrence of the speed change in the intermediate transfer belt 10 to suppress the deterioration of image quality. Since the tension adjusting means abuts on the rear surface of the intermediate transfer belt 10, the tension adjusting means does not come into contact with the image carried on the surface of the intermediate transfer belt 10, so that the image carried on the intermediate transfer belt 10 is not disturbed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, after the image developed on the surface of the latent image carrier is transferred from the latent image carrier to the front surface of the intermediate transfer belt, the transfer nip is brought into contact with the intermediate transfer belt and the secondary transfer roller. The present invention relates to a transfer device that transfers to a transfer material sandwiched between two. The present invention also relates to an image forming apparatus such as a printer, a copying machine, and a facsimile using the transfer device.

  In this type of image forming apparatus, when a speed fluctuation occurs in the intermediate transfer belt that is endlessly moved while being stretched by a plurality of stretching rollers, the image is transferred from the latent image carrier onto the intermediate transfer belt by the primary transfer unit. The image expands and contracts, and light and shade are generated in a portion that should have a constant image density. Further, in a multi-color image forming apparatus that sequentially superimposes and transfers images of different colors on the intermediate transfer belt, color shift occurs due to the speed fluctuation of the intermediate transfer belt.

  Regarding the speed fluctuation of the intermediate transfer belt whose speed increases or decreases in a certain period of time, feedback control is performed by detecting the speed fluctuation of the intermediate transfer belt and feeding back the result to the driving speed of the belt drive motor. The speed of the intermediate transfer belt can be stabilized. However, it is difficult to cope with the sudden speed fluctuation of the intermediate transfer belt due to the sudden load fluctuation by the above feedback control.

The sudden change in the speed of the intermediate transfer belt described above is caused when the transfer paper is passed through the secondary transfer nip formed by the secondary transfer roller and the opposing roller facing the secondary transfer roller via the intermediate transfer belt. It occurs in such as.
More specifically, as shown in FIG. 20, when the leading edge of the transfer paper enters the secondary transfer nip, the secondary transfer nip is pushed out by the thickness of the transfer paper S, and the driving of the counter roller 116 is suddenly performed. As a result, the rotation of the opposing roller 116 is temporarily slowed. As a result, the amount of belt sent from the driving roller 114 is larger than the amount of belt sent by the opposing roller 116, so that the intermediate transfer belt 110 becomes loose between the driving roller 114 and the opposing roller 116. Further, as shown in FIG. 21, when the trailing edge of the transfer sheet S passes through the secondary transfer nip, the load on the facing roller 116 is suddenly reduced, and the rotation of the facing roller 116 is primarily accelerated. As a result, the amount of belt sent out by the counter roller 116 is larger than the amount of belt sent out from the support roller 115, so that the intermediate transfer belt 110 becomes loose between the counter roller 115 and the support roller 116.
When the intermediate transfer belt 110 is loosened due to the load fluctuation that occurs when the transfer sheet S enters and exits the secondary transfer nip as described above, the speed fluctuation occurs in the intermediate transfer belt 110 that is rotating. For this reason, if an image is transferred from the photosensitive drum 104 to the intermediate transfer belt 110 at the primary transfer portion at this time, the image quality deterioration as described above occurs due to the speed fluctuation.

  In the image forming apparatus described in Patent Document 1, the intermediate transfer belt is bent inwardly on the inner side of the endless loop on the downstream side and the upstream side in the intermediate transfer belt rotation direction with respect to the secondary transfer nip of the endless loop-shaped intermediate transfer belt. A tension roller is brought into contact from the front side of the transfer belt, and the tension roller can be displaced according to a change in tension of the intermediate transfer belt by an elastic member provided on the tension roller. As a result, the tension roller is displaced in accordance with the tension change of the intermediate transfer belt accompanying the load variation caused when the transfer paper is passed through the secondary transfer nip, thereby adjusting the tension of the intermediate transfer belt. It is possible to suppress the occurrence of slack. Therefore, since it is possible to suppress the speed fluctuation from occurring in the intermediate transfer belt due to the load fluctuation, when the transfer paper is passed through the secondary transfer nip, the image is transferred from the photosensitive drum to the intermediate transfer belt at the primary transfer portion. Even if transfer is performed, it is possible to suppress the deterioration of image quality due to the speed fluctuation.

JP-A-2005-338884

  However, in the image forming apparatus described in Patent Document 1, since the tension roller is always in contact with the front surface of the intermediate transfer belt, the image transferred from the photosensitive drum to the front surface of the intermediate transfer belt. And the tension roller come into contact with each other, causing a problem that the image is disturbed.

  The present invention has been made in view of the above problems, and the object of the present invention is when the transfer paper is passed through the secondary transfer nip without disturbing the image carried on the intermediate transfer member. It is an object of the present invention to provide a transfer device capable of suppressing image deterioration caused by a transient load fluctuation and an image forming apparatus including the transfer device.

In order to achieve the above object, the invention of claim 1 is directed to a loop-shaped belt image carrier that is endlessly moved while being stretched by a plurality of tension rollers, and the plurality of tension belts via the belt image carrier. A transfer roller that faces one of the gantry rollers and abuts against a front surface of the belt image carrier, which is the outer surface of the loop, to form a transfer nip, and develops an image developed on the surface of the latent image carrier In a transfer apparatus for transferring an image carried on the front surface to a transfer material sandwiched in the transfer nip after being transferred from the surface to the front surface, a belt image carrier with respect to the transfer nip Tension that contacts the back surface, which is the inner surface of the loop of the belt image carrier, on the upstream side in the rotation direction and the downstream side of the belt image carrier, and adjusts the tension of the belt image carrier according to the change in tension of the belt image carrier Characterized by having adjusting means A.
According to a second aspect of the present invention, in the transfer device according to the first aspect, the tension adjusting means includes a first abutting member that abuts the back surface on the upstream side in the rotation direction of the belt image carrier, and the belt image carrier. A second abutting member that abuts against the back surface on the downstream side in the body rotation direction; and a supporting means that supports the first abutting member and the second abutting member in a displaceable manner. The first abutting member and the second abutting member are displaced via the support means in accordance with a change in tension of the belt image carrier.
According to a third aspect of the present invention, in the transfer apparatus according to the second aspect, the support means includes a first support member that supports the first contact member and a second support member that supports the second contact member. 2 and a holding member having a rotating shaft rotatable with respect to the apparatus main body and holding the first support member and the second support member. The contact member and the second contact member are rotatable about the rotation axis via the first support member and the second support member.
According to a fourth aspect of the present invention, in the transfer device according to the third aspect, an elastic member is provided between the holding member and the housing of the apparatus main body, and the holding member is inserted into the casing via the elastic member. It is characterized by being supported by.
According to a fifth aspect of the present invention, in the transfer device according to the third or fourth aspect, the holding member is provided with a weight, and the first contact member and the second contact member displaced from a predetermined reference position. The contact member returns to a predetermined reference position by gravity acting on at least the weight.
According to a sixth aspect of the present invention, in the transfer device according to the second aspect, the support means is slidable in a linear direction passing through the first abutting member and the second abutting member. One abutting member and the second abutting member can be displaced in the linear direction via the support means.
According to a seventh aspect of the present invention, in the transfer device according to the first, second, third, fourth, or sixth aspect, at least a part of the support means is made of an elastic body.
The invention according to claim 8 is the transfer apparatus according to claim 1, 2, 3, 4, 5, 6 or 7, wherein at least one of the first contact member and the second contact member is a roller. It is a member.
According to a ninth aspect of the present invention, in the transfer apparatus according to the first, second, third, fourth, fifth, sixth or seventh aspect, the belt image carrier of the first contact member and the second contact member. The surface in contact with the surface is a curved surface having a predetermined curvature.
According to a tenth aspect of the present invention, in the transfer device according to the first aspect, the tension adjusting means is a first abutting elastic member having elasticity that abuts on the back surface on the upstream side in the rotation direction of the belt image carrier. And a second abutting elastic member having elasticity that abuts against the back surface on the downstream side in the rotational direction of the belt image carrier, and the first abutment according to a change in tension of the belt image carrier. The elastic member and the second abutting elastic member are deformed.
The invention according to claim 11 is the transfer apparatus according to claim 10, wherein the first contact elastic member and the second contact elastic member have an elastic portion at a portion in contact with the belt image carrier. The elastic portion is formed by wrapping a predetermined gas with a flexible thin-walled member.
The invention according to claim 12 is the transfer apparatus according to claim 10, wherein at least one of the first abutting elastic member and the second abutting elastic member is a roller member, and the roller member is a hollow cylinder. And a rigid member having a high rigidity and an elastic support member having elasticity for supporting the rigid member inside the hollow cylinder of the rigid member.
The invention according to claim 13 is the transfer apparatus according to claim 10, 11 or 12, wherein the first contact elastic member and the second contact elastic member have different elastic moduli. Is.
Further, the invention of claim 14 is a latent image carrier for carrying a latent image, development means for developing a latent image carried on the latent image carrier to obtain a visible image, and a latent image carrier on the latent image carrier. An image forming apparatus including a transfer unit that transfers a visible image to a sheet member, wherein the transfer unit includes: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Alternatively, thirteen transfer devices are used.

In the present invention, the tension adjusting means contacting the back surface, which is the inner surface of the loop of the belt image carrier, on the upstream side in the belt image carrier rotation direction and the downstream side of the belt image carrier rotation with respect to the transfer nip, includes the belt image carrier. The tension of the belt image carrier can be adjusted according to the change in the tension of the body. As a result, even if the tension of the belt image carrier changes due to the load fluctuation that occurs when the transfer material enters and leaves the transfer nip, the tension adjusting means appropriately adjusts the tension according to the change in the tension. To prevent the belt image carrier from being slack. Therefore, it is possible to suppress the belt image carrier from slackening due to the load fluctuation that occurs when the transfer material enters and leaves the transfer nip, and the speed fluctuation of the rotating belt image carrier can be suppressed. . Therefore, even if the image is transferred from the latent image carrier to the belt image carrier when the transfer material enters and leaves the transfer nip, the image quality deteriorates due to the above speed fluctuation to the image transferred to the belt image carrier. Can be suppressed.
Further, since the tension adjusting means is in contact with the back surface of the belt image carrier, the tension adjusting means does not come into contact with the image carried on the front surface of the belt image carrier. The carried image is not disturbed.

  As described above, according to the present invention, image deterioration due to a transient load fluctuation that occurs when the transfer material enters and leaves the transfer nip without disturbing the image carried on the belt image carrier. There is an excellent effect that can be suppressed.

Embodiments in which the present invention is applied to a tandem type color image forming apparatus will be described below.
FIG. 2 is a schematic configuration diagram of a copying machine as an image forming apparatus according to the embodiment. The copying machine includes a copying machine main body (hereinafter referred to as a printer unit 100), a paper feed table (hereinafter referred to as a paper feed unit 200), a scanner attached to the printer unit 100 (hereinafter referred to as a scanner unit 300), and a scanner unit 300. An automatic document feeder (ADF) (hereinafter referred to as a document feeder 400) attached to the printer.

  The printer unit 100 includes an endless belt-like intermediate transfer belt 10 as an intermediate transfer member that is an image carrier at the center thereof. The intermediate transfer belt 10 is wound around a drive roller 14, a support roller 15, and a counter roller 16, and can move in the clockwise direction in the drawing. Then, four photosensitive drums 4K, 4Y, 4M as latent image carriers each carrying a toner image of one of black, yellow, magenta, and cyan on the surface so as to face the intermediate transfer belt 10. 4C is provided. Developing units 61K, 61Y, 61M, and 61C for forming toner images on the surfaces of the four photosensitive drums 4K, 4Y, 4M, and 4C are provided. Furthermore, there are also provided photoreceptor cleaning devices 63K, 63Y, 63M, and 63C for removing toner remaining on the surfaces of the photoreceptor drums 4K, 4Y, 4M, and 4C after the primary transfer. Four image forming units 18K, 18Y, 18M, 18C comprising four photosensitive drums 4K, 4Y, 4M, 4C, developing units 61K, 61Y, 61M, 61C, and photosensitive member cleaning devices 63K, 63Y, 63M, 63C. Are arranged side by side to constitute the tandem image forming unit 20. Further, a belt cleaning device that removes residual toner remaining on the intermediate transfer belt 10 after the toner image is transferred onto the transfer sheet S as a recording body so as to face the support roller 15 with the intermediate transfer belt 10 interposed therebetween. 17 is provided. Further, the printer unit 100 includes an exposure device 71 above the tandem image forming unit 20.

  Further, primary transfer rollers 62K, 62Y, 62M, and 62C are provided at positions inside the intermediate transfer belt 10 that face the photosensitive drums 4K, 4Y, 4M, and 4C with the intermediate transfer belt 10 interposed therebetween. The primary transfer rollers 62K, 62Y, 62M, and 62C are provided by being pressed against the photosensitive drums 4K, 4Y, 4M, and 4C with the intermediate transfer belt 10 interposed therebetween, thereby forming a primary transfer portion.

On the other hand, a secondary transfer roller 33 as a transfer roller is provided on the opposite side of the intermediate transfer belt 10 from the tandem image forming unit 20. The secondary transfer roller 33 is provided with a cleaning blade 122 as a secondary transfer roller cleaning unit. The secondary transfer roller 33 is pressed against the opposing roller 16 via the intermediate transfer belt 10, and a secondary transfer nip portion as a secondary transfer portion is formed between the secondary transfer roller 33 and the intermediate transfer belt 10. It is arranged to form. The secondary transfer roller 33 is driven at the same linear speed as the intermediate transfer belt 10 by a drive motor (not shown), and transfers the image on the intermediate transfer belt 10 to a sheet.
As described above, the toner image formed on the photosensitive drum 4 serving as the latent image carrier is transferred to the transfer sheet S by the transfer device 90 including the primary transfer roller 62, the intermediate transfer belt 10, the secondary transfer roller 33, and the like. Transcribed above.

  A sheet conveying belt 70 is arranged on the left side of the secondary transfer roller 33 in the drawing, and the sheet-like transfer sheet S is conveyed to a fixing device 75 arranged on the left side in the drawing. The fixing device 75 that fixes the transfer image on the transfer paper S is configured to press the pressure roller 77 against the fixing belt 76 that is an endless belt.

  Under the secondary transfer roller 33, the paper conveyance belt 70, and the fixing device 75, the transfer paper S that inverts the transfer paper S to record images on both sides of the transfer paper S in parallel with the tandem image forming unit 20 described above. A reversing device 78 is provided. As a result, after fixing the image on one side of the transfer sheet S, the path of the transfer sheet S is switched to the transfer sheet S reversing device side with the switching claw, and the transfer sheet S is reversed and transported to the secondary transfer nip portion again. After the image is transferred, it can be discharged onto a discharge tray.

  The scanner unit 300 reads the image information of the document placed on the contact glass 332 with the reading sensor 336, and sends the read image information to the control unit.

  Based on the image information received from the scanner unit 300, a control unit (not shown) controls a laser, an LED (not shown) disposed in the exposure device 71 of the printer unit 100, and lasers the photosensitive drum 4 toward the photosensitive drum 4. The writing light L is irradiated. By this irradiation, an electrostatic latent image is formed on the surface of the photosensitive drum 4, and this latent image is developed into a toner image via a predetermined development process.

  The paper feed unit 200 includes paper cassettes 44 provided in multiple stages in the paper bank 43, a paper feed roller 42 that feeds the transfer paper S from the paper feed cassette, and a separation roller 45 that separates the fed transfer paper S and sends it to the paper feed path 46. Further, a transport roller 47 for transporting the transfer paper S to the paper feed path 48 of the printer unit is provided.

  In the copying machine according to the present embodiment, manual paper feeding is possible in addition to the paper feeding unit 200, and the manual feed tray 51 for manual feeding and the transfer sheet S on the manual tray 51 are directed toward the manual paper feed path 53. A separation roller 52 for separating the sheets one by one is also provided on the side of the apparatus.

  The registration roller 49 discharges only one sheet of transfer paper S placed on the paper feed cassette 44 or the manual feed tray 51, and is positioned between the intermediate transfer belt 10 as the intermediate transfer member and the secondary transfer roller 33. To the secondary transfer nip.

Next, image formation by the color electrophotographic apparatus having the above configuration will be described.
In the copying machine of the present embodiment, when copying a color image, an original is set on the original platen 330 of the original conveying unit 400, or the original conveying unit 400 is opened and the original is placed on the contact glass 332 of the scanner unit 300. Is set and the original conveying unit 400 is closed to hold the original.
When a start switch (not shown) is pressed, the original is conveyed onto the contact glass 332 when the original is set on the original conveying unit 400, and immediately after the original is set on the other contact glass 332, the scanner The part 300 is driven to travel on the first traveling body 333 and the second traveling body 334. Then, the first traveling body 333 emits light from the light source, and the reflected light from the document surface is further reflected and directed to the second traveling body 334. This reflected light is further reflected by the mirror of the second traveling body 334 and enters the reading sensor 336 through the imaging lens 335. Thereby, the content of the original is read.

When image information is received from the scanner unit, a laser image as described above or a development process described later is performed to form a toner image on the photosensitive drum 4, and a transfer sheet having a size corresponding to the image information. To feed S, one of the four feed rollers is activated.
Along with this, the drive roller 14 is driven to rotate by a drive motor (not shown), the support roller 15 and the opposing roller 16 are driven to rotate, and the intermediate transfer belt 10 is rotated and conveyed. At the same time, the photosensitive drums 4 are rotated by the individual image forming units 18, and black, yellow, magenta, and cyan single-color images are formed on the photosensitive drums 4, respectively. Then, along with the conveyance of the intermediate transfer belt 10, these single color images are sequentially transferred onto the surface of the intermediate transfer belt 10 to form a composite color image on the intermediate transfer belt 10.

On the other hand, in the paper feed unit 200, one of the paper feed rollers 42 is selectively rotated, and the transfer paper S is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43. The transferred transfer paper S is separated one by one by a separation roller 45 and introduced into a paper feed path 46, conveyed by a conveyance roller 47, and also fed to a paper feed path 48 in the printer unit 100, which is a copying machine body. It is guided and abutted against the registration roller 49 and stopped. When the manual feed tray 51 is used, the paper feed roller 50 is rotated, and the transfer paper S on the manual feed tray 51 is fed out. The fed transfer paper S is manually separated by the separation roller 52 one by one. The sheet is put in the sheet feeding path 53 and is also abutted against the registration roller 49 and stopped. When the transfer paper S on the manual feed tray 51 is used, the paper feed roller 50 is rotated to feed out the transfer paper S on the manual feed tray 51, and the fed transfer paper S is separated by the separation roller 52. After being separated one by one, it is introduced into the manual paper feed path 53 and similarly abutted against the registration roller 49 and stopped.
Then, the registration roller 49 is rotated in time with the composite color image on the intermediate transfer belt 10, and the transfer sheet S is placed at the secondary transfer nip portion where the intermediate transfer belt 10 and the secondary transfer roller 33 are in contact with each other. It is sent. Then, the color image is secondarily transferred by the influence of the transfer electric field and contact pressure formed in the nip, and the color image is recorded on the transfer paper S.

After the transfer of the color image at the secondary transfer nip portion, the transfer sheet S is transported by the sheet transport belt 70 and sent to the fixing device 75, and the fixing device 75 adds the pressure roller 77 and the fixing belt 76. A color image is fixed by applying pressure and heat. Thereafter, the paper is discharged by a discharge roller 56 and stacked on a paper discharge tray 57. Further, after the color image is fixed, the transfer paper S on which both sides are formed is switched by the switching claw 55 and conveyed to the transfer paper S reversing device 78, where it is reversed and led again to the secondary transfer nip portion. After the image is also recorded on the back surface, the paper is discharged onto the paper discharge tray 57 by the discharge roller 56.
On the other hand, the residual toner remaining on the surface of the intermediate transfer belt 10 after the color image is transferred to the transfer sheet S at the secondary transfer nip portion is removed by the belt cleaning device 17, and the tandem image forming unit 20 forms the image again. Prepare for.

  Further, since the secondary transfer roller 33 is in contact with the intermediate transfer belt 10, the background stain toner and the process pattern on the intermediate transfer belt 10 are not printed on the recording material such as the transfer paper S or between the sheets. Transfer is performed and the secondary transfer roller 33 is soiled. If there is dirt on the surface of the secondary transfer roller 33, the dirt causes the back dirt to adhere to the back side of the transfer paper S when performing the secondary transfer on the transfer paper S. Is in contact with a cleaning blade 122 as a secondary transfer roller cleaning means for removing dirt on the surface. The cleaning blade 122 always removes dirt such as toner on the secondary transfer roller 33, thereby preventing the back surface of the transfer paper S from becoming dirty. In addition, in order to prevent calcium carbonate or the like, which is a paper additive, from adhering to cause filming, a solid lubricant 124 obtained by solidifying zinc stearate is directly applied to the surface of the secondary transfer roller 33. The next transfer roller 33 is applied in contact with the surface.

  In such a color copying machine, since the load fluctuation when the paper enters the transfer portion greatly affects the accuracy of superimposing the four colors, it is particularly desirable to drive the intermediate transfer belt 10 with high accuracy.

FIG. 3 shows a basic configuration of the transfer device 90 according to the present embodiment, and the intermediate transfer belt 10 is driven by the transfer device 90 shown in FIG. Give an explanation.
A drive roller 14 is attached so as to be coaxial with the gear 3 as shown in FIG. The motor 1 is mounted so as to be coaxial with the gear 2, and the driving roller 14 is driven from the motor 1 through the gear 2 and the gear 3. An intermediate transfer belt 10 to be driven is placed on the drive roller 14, the support roller 15, and the counter roller 16, and a constant tension is applied by the support roller 15. There are no particular restrictions on the motor type of the motor 1. For example, there is a method of inputting a constant pulse in the case of a pulse motor, and driving the motor with high accuracy from an internal FG signal or the like in the case of a brushless DC motor, for example. Although not shown here, a rotary encoder or the like is attached to the same side as the gear 3 or the end of the driving roller 14 on the opposite side of the gear 3 or the position opposite to the opposing roller 16 and the support roller 15. A method of measuring the driving state of the intermediate transfer belt 10 from the encoder signal and controlling the motor 1 may be a method for achieving high-precision driving. Further, although not shown, a scale capable of measuring the rotation state is provided on the front surface or the back surface of the intermediate transfer belt 10 and a sensor capable of detecting the driving state of the intermediate transfer belt 10 from the scale. A method of controlling the motor 1 by measuring the driving state may be used.

  In the transfer device 90, a toner image or the like is formed on the intermediate transfer belt 10 by an image forming unit (not shown). Further, a secondary transfer roller 33 is pressed against the opposing roller 16 to form a secondary transfer nip portion, and the transfer paper S passes through the secondary transfer nip portion between the opposing roller 16 and the secondary transfer roller 33. The toner image on the intermediate transfer belt 10 is transferred onto the transfer paper S. Here, the secondary transfer roller 33 is provided at a position facing the facing roller 16, but a structure facing the driving roller 14 may be used.

  In the transfer device 90 having such a configuration, when the transfer sheet S is passed through the secondary transfer nip portion, a transient load fluctuation occurs when the transfer sheet S leaves when entering the secondary transfer nip portion. Due to this load fluctuation, the driving of the intermediate transfer belt 10 and the opposing roller 16 is hindered.

  At the time of continuous paper transfer, the transfer from the intermediate transfer belt 10 to the transfer paper S is performed, and at the same time, the toner image is also transferred from the photosensitive drum 4 (not shown) to the intermediate transfer belt 10. The transient load fluctuation caused by passing the paper through the secondary transfer nip part also affects the primary transfer from the photosensitive drum 4. For example, when a black solid image having a 50% density is output, the formed image is shown in FIG. 4 in the middle of the same transfer sheet S when it is long in the direction of the intermediate transfer belt 10 and when it is short as shown in FIG. A streaky dark portion D and a thin portion L are formed. In the case of an image forming apparatus in which four color toner images are formed on the four photosensitive drums 4 and superimposed on the intermediate transfer belt 10 to form a color image, the above-described transient load fluctuation occurs. At this time, in an image to be overlaid on the intermediate transfer belt 10, an image in which an image that has undergone the transient load fluctuation and an image that has not been received are overlaid is generated, and color misregistration occurs.

  The contact of the transfer sheet S with the intermediate transfer belt 10 is necessary from the relationship of the transfer process. In order to transfer the toner image from the intermediate transfer belt 10 to the transfer paper S, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image formed on the surface of the intermediate transfer belt 10 is applied to the secondary transfer roller 33. As a result, the toner image on the intermediate transfer belt 10 is transferred to the surface of the transfer sheet S that moves while contacting the surface of the intermediate transfer belt 10. By simultaneously applying pressure, it becomes possible to transfer the toner image to the transfer paper S more reliably, so that an arbitrary pressure is applied to the secondary transfer nip portion. For this reason, in the secondary transfer nip portion where the image on the intermediate transfer belt 10 is transferred to the transfer paper S, for example, the transfer paper S enters the secondary transfer nip portion to push the narrow space. Sudden speed fluctuations occur where the rotational speed of the intermediate transfer belt is decelerated due to load fluctuations.

  More specifically, the sudden change in the speed of the intermediate transfer belt 10 is formed by sandwiching the intermediate transfer belt 10 between the secondary transfer roller 33 as a transfer member and the opposing roller 16 as a nip-side stretching roller as described above. This occurs when the paper is passed through the secondary transfer nip. That is, when the leading edge of the transfer sheet S enters the secondary transfer nip, the load on the secondary transfer roller 33 and the intermediate transfer belt 10 suddenly increases, and the increase in the load causes the speed of the intermediate transfer belt 10 to increase. Suddenly drops. That is, when the transfer sheet S enters the secondary transfer nip portion, a transient load fluctuation occurs, and a load is applied to the driving of the facing roller 16. As a result, the rotation of the counter roller 16 is temporarily delayed. At this time, the amount of the belt sent out from the driving roller 14 is larger than the amount of the belt sent out by the facing roller 16, so that the intermediate transfer belt 10 becomes loose between the driving roller 14 and the facing roller 16. On the other hand, since the amount of belt sent out by the support roller 15 is larger than the amount of belt sent by the facing roller 16, the intermediate transfer belt 10 between the facing roller 16 and the supporting roller 15 becomes tight. Therefore, when the transfer sheet S enters the secondary transfer nip portion, the rotation path of the intermediate transfer belt 10 changes from the path A to the path A ′ between the driving roller 14 and the opposing roller 16 as shown in FIG. End up. In FIG. 5, the rotation path of the intermediate transfer belt 10 is extremely changed for easy understanding. However, since an arbitrary tension is actually applied, the speed of the intermediate transfer belt 10 fluctuates as it is, and the intermediate transfer belt 10 The speed of 10 is reduced. This also affects the primary transfer portion that transfers the image from the photosensitive drum 4 to the intermediate transfer belt 10, that is, if the image on the latent image carrier is primarily transferred to the intermediate transfer belt 10, The image on 10 is shrunk and the image density becomes higher than a predetermined value.

  Further, when the trailing edge of the transfer sheet S passes through the secondary transfer nip portion, the load on the opposing roller 16 and the intermediate transfer belt 10 is suddenly reduced. Due to such a decrease in load, the speed of the intermediate transfer belt 10 suddenly increases. As a result, the intermediate transfer belt 10 becomes tight between the driving roller 14 and the opposing roller 16, and the intermediate transfer belt 10 becomes loose between the opposing roller 16 and the support roller 15, contrary to the approach. At this time, if the image is primarily transferred from the photosensitive drum 4 to the intermediate transfer belt 10, the image on the intermediate transfer belt 10 is stretched and the image density becomes lower than a predetermined value.

  As a basic drive system in the transfer device 90, a drive roller is connected via a transmission mechanism such as a gear to move the intermediate transfer belt 10 at a constant speed, or a DC motor or a pulse motor is directly coupled to the motor shaft. It is widely used that a rotation angle detector or angular velocity detector such as a rotary encoder is provided coaxially with the drive roller shaft or the driven roller shaft, and the detector output is fed back and controlled. In particular, when a rotation angle detector such as a rotary encoder or an angular velocity detector is provided coaxially with the driven roller shaft, the influence of slippage between the drive roller and the intermediate transfer belt 10 is reduced.

  Here, the case where feedback control is performed on the intermediate transfer belt 10 of FIG. 3 using the rotation angle or angular velocity by the encoder 40 attached to the opposing roller 16 will be described with reference to FIG.

  An encoder 40 is provided so as to be coaxial with the facing roller 16, and rotation angle or angular velocity information is input from the encoder 40 to the calculation unit 41. The calculation unit 41 sets a target value for driving the intermediate transfer belt, compares the measured rotation angle or angular velocity, and generates a new drive signal. The generated new drive signal is input to the driver 42, and the driver performs acceleration / deceleration control of the motor in accordance with the drive signal. That is, when the intermediate transfer belt speed is low, the speed is increased, and when the speed is high, the speed is decreased. This is the drive control system shown here.

  However, the transient load fluctuation that occurs when the transfer sheet S enters the secondary transfer nip portion is detected in the feedback control, and then the fluctuation is detected and then the correction control is performed. Will exist. For this reason, the drive correction of the drive roller 14 caused by this transient load fluctuation is not in time. Various feedback elements are included in the feedback loop. As an example of the rotary encoder, a timing mark with an equal pitch is formed on a glass disk on a concentric circle with a rotation axis as the center, and is formed coaxially with the roller. This is optically detected using a light emitting element and a light receiving element provided in the fixed portion. The output is a continuous pulse train. Therefore, since the rotation angle or rotation angular velocity information can be obtained only discretely, a time delay occurs here. In addition, when rotational control due to transient load fluctuations is detected by rotary encoder information and feedback control is performed, there is a delay in driving force due to time delay due to the phase compensation circuit, back electromotive force of the DC motor, or current waveform rounding due to internal inductance. appear.

  Therefore, in the copying machine according to the present embodiment, transients that occur when the transfer sheet S is passed through the intermediate transfer belt 10 to the secondary transfer nip portion constituted by the opposing roller 16 and the secondary transfer roller 33. In order to suppress the speed fluctuation of the intermediate transfer belt 10 due to a typical load fluctuation, the intermediate transfer belt 10 is brought into contact with the back surface of the intermediate transfer belt 10 on the upstream side and the downstream side in the rotation direction of the intermediate transfer belt from the secondary transfer nip portion. Tension adjusting means for adjusting is provided in the transfer device 90, and the tension change of the intermediate transfer belt 10 due to the load fluctuation is adjusted by the tension adjusting means so that the speed fluctuation does not occur in the intermediate transfer belt 10 due to the tension change. .

[Configuration example 1]
FIG. 1 specifically shows the configuration of the transfer device 90 of Configuration Example 1. Adjustment to contact the back surface of the intermediate transfer belt 10 upstream and downstream in the intermediate transfer belt rotation direction with respect to the secondary transfer nip portion constituted by the counter roller 16 and the secondary transfer roller 33 in the intermediate transfer belt loop. The tension of the intermediate transfer belt 10, which includes rollers 20 and 21 and support members 23 and 24 that support the adjustment rollers 20 and 21 and are coupled by a holding member 22 that is rotatable with respect to the apparatus main body, is adjusted. A tension adjusting means is provided. The holding member 22 has a rotating shaft, and is fixed to the apparatus main body by the rotating shaft here by a mechanism (not shown).

Next, the behavior when a transient load fluctuation occurs due to the transfer paper S passing through the secondary transfer nip portion in the transfer device 90 having such a configuration will be described.
The state of the transfer device 90 at the time of constant rotation driving when the transfer sheet S does not pass through the secondary transfer nip portion is as shown in FIG. 1, and the transfer sheet S has not yet touched the intermediate transfer belt 10 and is adjusted. The rollers 20 and 21 are in the respective reference positions B and C. Further, the rotation path of the intermediate transfer belt 10 at this time becomes the reference position.

  Next, FIG. 7A shows a state in which the transfer sheet S has entered the secondary transfer nip portion. Since the leading edge of the transfer sheet S spreads the secondary transfer nip portion, load fluctuation occurs in the intermediate transfer belt 10 and the opposing roller 16, and the rotation of the opposing roller 16 is temporarily slowed. On the upstream side of the intermediate transfer belt rotation direction, the intermediate transfer belt 10 feels slack, and conversely, on the downstream side of the intermediate transfer belt, the intermediate transfer belt 10 becomes tight. Thus, the adjustment roller 21 provided on the upstream side is rotated from the reference position C to C ′ by the rotation of the holding member 22 in response to a change in the tension of the intermediate transfer belt 10 such that the intermediate transfer belt 10 is loosened. The adjustment roller 20 provided on the downstream side is displaced from the reference position B to B ′. It is possible to appropriately correct the tension of the intermediate transfer belt 10 so that the tension of the intermediate transfer belt 10 is not loosened due to the displacement of the adjustment rollers 20 and 21. Therefore, the transient load fluctuation that occurs when the transfer sheet S enters the secondary transfer nip portion affects the intermediate transfer belt in the vicinity of the secondary transfer nip portion. By adjusting the tension, the influence of the load fluctuation is suppressed from the photosensitive drum 4 to the primary transfer portion where the visible image is transferred onto the intermediate transfer belt 10, in other words, in the vicinity of the primary transfer portion. It is possible to prevent the speed fluctuation of the intermediate transfer belt 10 from occurring. Further, since the displacement amounts of the adjusting rollers 20 and 21 are determined by the rotation of the holding member 22 to which the adjustment rollers 20 and 21 are coupled, the change with respect to the intermediate transfer belt 10 becomes zero as a whole, and the belt driving system is not adversely affected.

  Next, FIG. 7B shows a state in which the transfer paper S is separated from the secondary transfer nip portion. As the trailing edge of the transfer sheet S slips out of the secondary transfer nip, the pressure applied to the opposing roller 16 decreases transiently, so that the intermediate transfer belt 10 becomes tight on the upstream side as opposed to entering, and the above On the downstream side, the intermediate transfer belt 10 becomes loose. In response to such a change in tension of the intermediate transfer belt 10, the adjustment roller 21 provided on the upstream side is displaced to C ″ by the rotation of the holding member 22, and the adjustment roller 20 provided on the downstream side. Is displaced to B ″. By performing the above-described operation even when the transfer sheet S moves away from the secondary transfer nip portion in this way, the tension of the intermediate transfer belt 10 is appropriately corrected so that the tension of the intermediate transfer belt 10 does not occur due to the displacement of the adjustment rollers 20 and 21. Therefore, the influence of the load fluctuation generated in the secondary transfer nip part up to the primary transfer part is suppressed, in other words, the speed fluctuation of the intermediate transfer belt 10 in the vicinity of the primary transfer part is suppressed. it can.

  Further, even when the low-quality transfer paper S is used by adjusting the tension of the intermediate transfer belt 10 by the adjustment rollers 20 and 21 according to the shape of the transfer paper S (such as unevenness of the paper surface). It is possible to prevent the load fluctuation from affecting the primary transfer portion, and it is possible to suppress deterioration in image quality.

  Further, in the configuration of the configuration example 1, the adjustment rollers 20 and 21 are opposite to each other on the upstream side and the downstream side of the secondary transfer nip portion (one is in contact with the belt so as to apply tension, and the other is in the belt Therefore, if the transfer sheet S is not present in the secondary transfer nip portion, the rotation path of the intermediate transfer belt 10 becomes the reference position, so that the adjustment rollers 20 and 21 are The holding member 22 is automatically returned to the reference positions B and C by rotating. Here, FIG. 8 shows one configuration for reliably returning the adjustment rollers 20 and 21 to the reference position when the transfer sheet S is separated from the secondary transfer nip portion. As shown in FIG. 8, the adjustment rollers 20 and 21 are returned to the reference positions B and C, and the balance weight is placed at a rotatable position inside or outside the rotatable holding member 22 so as not to obstruct the movement of the support members 23 and 24. 25 is provided. The balance weight 25 is fixed at a position where a pendulum composed of the adjustment rollers 20 and 21 and the support members 23 and 24 stops at the reference position by the action of the balance weight 25 due to gravity. By providing the balance weight 25, the adjustment rollers 20 and 21 after the transfer sheet S is separated from the secondary transfer nip portion are reinforced so that the adjustment rollers 20 and 21 return to the reference positions B and C. It becomes possible to return to positions B and C.

  Furthermore, in order to reduce the vibration after the adjusting rollers 20 and 21 are displaced, the elastic members 26 and 27 are provided on a part of the support members 23 and 24 in FIG. Here, a part of the support members 23 and 24 is configured as the elastic bodies 26 and 27. However, the support members 23 and 24 may be configured as all elastic bodies. The adjustment rollers 20 and 21 and the support members 23 and 24 may vibrate due to the displacement of the adjustment rollers 20 and 21 after a transient load fluctuation occurs when the transfer paper S passes through the secondary transfer nip portion. is there. Therefore, by constituting a part of the support members 23 and 24 with the elastic bodies 26 and 27, undesirable vibrations generated after the adjusting rollers 20 and 21 are displaced can be absorbed by the elastic bodies 23 and 24. Accordingly, the tension of the intermediate transfer belt 10 can be appropriately adjusted.

  Moreover, it is good also as a structure which reduces the said vibration by the friction of a rigid body and an elastic body by comprising all the support members 23 and 24 by a rigid body, and setting it as the structure inserted | pinched with an elastic body. Further, by adopting a configuration in which a viscous member is interposed in the connecting portion between the support members 23 and 24 and the holding member 22, the adjustment rollers 20 and 21 are surely displaced, and undesirable vibrations generated thereafter are viscous. It may be absorbed by a member so that the tension of the intermediate transfer belt 10 can be appropriately adjusted.

  In addition, as shown in FIG. 10, an elastic member 32 is provided between the holding member 22 and the housing of the apparatus main body, and the holding member 22 is adjusted by being supported by the housing via the elastic member 32. The reference position of the rollers 20 and 21 can be determined, and vibration after the adjustment rollers 20 and 21 are moved can be reduced. The elastic member 32 is provided so that the holding member 22 including the adjusting rollers 20 and 21 is supported by the housing at an initial desired position, that is, the reference position. When the transfer sheet S is not in the secondary transfer nip portion, the holding member 22 is supported by the elastic member 32 with respect to the casing at the reference position.

  When a transitional load fluctuation occurs due to the transfer sheet S entering the secondary transfer nip portion, the adjustment rollers 20 and 21 are displaced, and undesirable vibrations of the adjustment rollers 20 and 21 are caused by the damping characteristics of the elastic member 32. Therefore, the tension of the intermediate transfer belt 10 can be appropriately adjusted so that the intermediate transfer belt 10 does not loosen. As a result, the occurrence of speed fluctuations in the intermediate transfer belt 10 in the vicinity of the primary transfer portion is suppressed. be able to.

  Further, since the reference positions B and C of the adjustment rollers 20 and 21 are determined by the elastic member 32, the holding member 22 rotates and the adjustment rollers 20 and 21 return to the reference positions B and C when the load fluctuation is eliminated. be able to.

  As described above, according to the first configuration example, even when the load fluctuation occurs due to the transfer sheet S being passed through the secondary transfer nip portion, the upstream side and the downstream side with respect to the secondary transfer nip portion. The adjustment rollers 20 and 21 provided on the center of the holding member 22 are displaced through the support members 23 and 24 about the rotation axis of the holding member 22 to adjust the tension of the intermediate transfer belt 10. As a result, the intermediate transfer belt 10 is prevented from being loosened, and the influence of the load fluctuation on the primary transfer portion is suppressed, that is, the speed fluctuation of the intermediate transfer belt 10 in the vicinity of the primary transfer portion is suppressed. The intermediate transfer belt 10 can be driven with high accuracy, and image degradation caused by transient load fluctuations (speed fluctuations of the intermediate transfer belt 10) during image transfer onto the intermediate transfer belt 10 in the primary transfer portion. Can be suppressed. Further, since the adjustment rollers 20 and 21 are in contact with the back surface of the intermediate transfer belt 10, the adjustment rollers 20 and 21 do not contact the image carried on the front surface of the intermediate transfer belt 10, and the adjustment roller 20 and 21 do not disturb the image carried on the intermediate transfer belt 10.

[Configuration example 2]
FIG. 11 shows the configuration of the transfer device 90 of Configuration Example 2. An adjustment roller 20 that is in contact with the back surface of the intermediate transfer belt 10 on the upstream side and the downstream side in the intermediate transfer belt rotation direction of the secondary transfer nip portion constituted by the opposing roller 16 and the secondary transfer roller 33 inside the intermediate transfer belt loop. , 21 and a support member 29 that supports the two adjustment rollers 20, 21 are provided to adjust the tension of the intermediate transfer belt 10. Here, the supporting member 29 is held so as to be movable only in the linear direction passing through the adjusting rollers 20 and 21 by a holding mechanism (not shown), and does not move in the other directions.

Next, the behavior when a transient load fluctuation occurs due to the transfer paper S passing through the secondary transfer nip portion in the transfer device 90 having such a configuration will be described.
The state of the transfer device 90 at the time of constant rotation driving when the transfer paper S is not passed through the secondary transfer nip portion is as shown in FIG. 11, and the transfer paper S has not yet touched the intermediate transfer belt 10, The adjustment rollers 20 and 21 are in the reference positions E and F. Further, the rotation path of the intermediate transfer belt 10 at this time becomes the reference position.

  Next, FIG. 12A shows a state in which the transfer sheet S has entered the secondary transfer nip portion. Since the leading edge of the transfer sheet S spreads the secondary transfer nip portion, load fluctuation occurs in the intermediate transfer belt 10 and the opposing roller 16, and the rotation of the opposing roller 16 is temporarily slowed. On the upstream side of the intermediate transfer belt rotation direction, the intermediate transfer belt 10 feels slack, and conversely, on the downstream side of the intermediate transfer belt, the intermediate transfer belt 10 becomes tight. The adjustment roller 21 provided on the upstream side moves as a reference when the support member 29 moves in the linear direction with respect to the tension change of the intermediate transfer belt 10 such that the intermediate transfer belt 10 is loosened. The position is displaced from the position F to F ′, and the adjusting roller 20 provided on the downstream side is displaced from the reference position E to E ′. It is possible to appropriately correct the tension of the intermediate transfer belt 10 so that the tension of the intermediate transfer belt 10 is not loosened due to the displacement of the adjustment rollers 20 and 21. Therefore, the transient load fluctuation that occurs when the transfer sheet S enters the secondary transfer nip portion affects the intermediate transfer belt in the vicinity of the secondary transfer nip portion. By adjusting the tension, the influence of the load fluctuation is suppressed from the photosensitive drum 4 to the primary transfer portion where the image is transferred onto the intermediate transfer belt 10, in other words, the intermediate transfer in the vicinity of the primary transfer portion. The speed fluctuation of the belt 10 can be suppressed. Further, since the displacement amount of the adjusting rollers 20 and 21 is determined by the linear movement of the support member 29, the change with respect to the intermediate transfer belt 10 becomes zero as a whole, and the belt driving system is not adversely affected.

  Next, FIG. 7B shows a state in which the transfer paper S is separated from the secondary transfer nip portion. As the trailing edge of the transfer sheet S slips out of the secondary transfer nip, the pressure applied to the opposing roller 16 decreases transiently, so that the intermediate transfer belt 10 becomes tight on the upstream side as opposed to entering, and the above On the downstream side, the intermediate transfer belt 10 becomes loose. In response to such a change in tension of the intermediate transfer belt 10, the adjustment roller 21 provided on the upstream side is displaced to F ″ by the linear movement of the support member 29, and the adjustment provided on the downstream side. Roller 20 is displaced to E ″. By performing the above-described operation even when the transfer sheet S moves away from the secondary transfer nip portion in this way, the tension of the intermediate transfer belt 10 is appropriately corrected so that the tension of the intermediate transfer belt 10 does not occur due to the displacement of the adjustment rollers 20 and 21. Therefore, it is possible to suppress the influence of the load variation generated in the secondary transfer nip portion up to the primary transfer portion, in other words, to suppress the speed variation of the intermediate transfer belt 10 in the vicinity of the primary transfer portion. it can.

  Further, even when the low-quality transfer paper S is used by adjusting the tension of the intermediate transfer belt 10 by the adjustment rollers 20 and 21 according to the shape of the transfer paper S (such as unevenness of the paper surface). It is possible to prevent the load fluctuation from affecting the primary transfer portion, and it is possible to suppress deterioration in image quality.

  In the transfer device 90 of the configuration example 2, the rotation path of the intermediate transfer belt 10 is the reference position except when the load is changed by passing the transfer sheet S through the secondary transfer nip portion. The adjusting rollers 20 and 21 are automatically returned to the steady reference positions E and F. Therefore, parts such as the balance weight 25 used in the configuration example 1 for returning the adjustment rollers 20 and 21 to the reference positions E and F are not required. Further, in the transfer device 90 of the configuration example 2, the adjustment rollers 20 and 21 are displaced only by the linear motion of the support member 29, so that the configuration is simplified and the number of parts can be reduced as compared with the transfer device 90 of the configuration example 1. Become. This also reduces the inertial force of the tension adjusting means itself, so that the response to the load fluctuation is better than the configuration applied to the transfer device 90 of Configuration Example 1.

  Furthermore, in order to reduce the vibration after the adjusting rollers 20 and 21 and the support member 29 are displaced, a part of the support member 29 provided with an elastic body 28 is shown in FIG. Here, a part of the support member 29 is configured to be the elastic body 28, but a configuration in which the support member 29 is entirely elastic body may be used.

  The adjustment rollers 20 and 21 and the support members 23 and 24 may vibrate due to the displacement of the adjustment rollers 20 and 21 after a transient load fluctuation occurs when the transfer paper S passes through the secondary transfer nip portion. is there. Therefore, by constituting a part of the support member 29 with the elastic body 28, undesirable vibrations that occur after the adjusting rollers 20 and 21 are displaced can be absorbed by the elastic body 28, so that stable correction operation, that is, intermediate transfer can be performed. The tension of the belt 10 can be adjusted appropriately.

  Moreover, it is good also as a structure which reduces the said vibration by friction with a rigid body and an elastic body by comprising all the support members 29 with a rigid body, and setting it as the structure inserted | pinched with an elastic body. Further, a part of the support member 29 is sealed with a viscous member, and the viscous member is fixed, so that the displacement of the adjusting rollers 20 and 21 is ensured, and undesirable vibrations that occur thereafter are caused by the viscous member. The tension may be absorbed so that the tension of the intermediate transfer belt 10 can be appropriately adjusted.

  As described above, according to the configuration example 2, the adjustment rollers 20 and 21 support the tension change of the intermediate transfer belt 10 due to the transient load fluctuation caused by the transfer sheet S being passed through the secondary transfer nip portion. By performing a linear motion via the member 29, the intermediate transfer belt 10 is appropriately adjusted so that no slack occurs. As a result, the intermediate transfer belt 10 is prevented from being loosened, and the influence of the load fluctuation on the primary transfer portion is suppressed, that is, the speed fluctuation of the intermediate transfer belt 10 in the vicinity of the primary transfer portion is suppressed. The intermediate transfer belt 10 can be driven with high accuracy, and image degradation caused by transient load fluctuations (speed fluctuations of the intermediate transfer belt 10) during image transfer onto the intermediate transfer belt 10 in the primary transfer portion. Can be suppressed. Further, since the adjustment rollers 20 and 21 are in contact with the back surface of the intermediate transfer belt 10, the adjustment rollers 20 and 21 do not contact the image carried on the front surface of the intermediate transfer belt 10, and the adjustment roller 20 and 21 do not disturb the image carried on the intermediate transfer belt 10.

  Here, although the configuration of the adjustment roller used in the configuration example 1 and the configuration example 2 may be other configurations, such an example is shown in FIG.

  Usually, in order to reduce friction with the intermediate transfer belt 10, a roller member 81 as shown in FIG. 14A is generally used as a member to be brought into contact with the intermediate transfer belt 10. However, it is possible to cope with the case where the transitional load fluctuation due to the transfer sheet S entering the secondary transfer nip is small, the tension change of the intermediate transfer belt 10 is small, and the displacement of the rotation path of the intermediate transfer belt 10 is small. Further, it is desirable that the inertia of the adjusting means for adjusting the tension of the intermediate transfer belt 10 is as small as possible. FIG. 14B shows an example of a configuration in which the inertia is lowered. The rotation center of the support member 82 and the fixed member 83 having a fan-shaped cross section are connected. Around the fixing member 83, a rotating cylinder 84 whose inertia is lowered by thinning the wall can be smoothly fixed and is configured as a fixing member 83. The fixing member 83 preferably has a shape only at a portion in contact with the intermediate transfer belt 10, but may have a configuration slightly larger or smaller than the portion in contact. As described above, the member to be brought into contact with the intermediate transfer belt 10 is constituted by the fixed member 83 and the rotating cylinder 84, so that necessary rigidity can be ensured while lowering the inertia.

  Another configuration is shown in FIG. Instead of the roller member, a contact member 85 having a shape of a portion in contact with the intermediate transfer belt 10 having a predetermined curvature that is substantially the same as the curvature of the rotation path of the intermediate transfer belt 10 is the intermediate transfer belt 10. It is constructed so that it touches smoothly. If other operations are not hindered, a method using powder or a viscous member is also possible. By configuring the tension adjusting means using these, it is possible to reduce inertia compared to using a roller member as a member that contacts the intermediate transfer belt 10.

[Configuration example 3]
FIG. 15 shows the configuration of the transfer device 90 of Configuration Example 3. The intermediate transfer belt loop is in contact with the back surface of the intermediate transfer belt 10 on the upstream side and the downstream side in the rotation direction of the intermediate transfer belt with respect to the secondary transfer nip portion constituted by the opposing roller 16 and the secondary transfer roller 33. Adjustment rollers 30 and 31 having an arbitrary elastic coefficient are provided as tension adjusting means for adjusting the tension of the intermediate transfer belt 10.

Next, the behavior when a transient load fluctuation occurs due to the transfer paper S passing through the secondary transfer nip portion in the transfer device 90 having such a configuration will be described.
The state of the transfer device 90 at the time of constant rotation driving when the transfer paper S does not pass through the secondary transfer nip portion is as shown in FIG. 15, and the transfer paper S has not yet touched the intermediate transfer belt 10, The outer peripheral positions of the adjustment rollers 30 and 31 are in the reference positions G and H. Further, the rotation path of the intermediate transfer belt 10 at this time becomes the reference position.

  Next, FIG. 16A shows a state in which the transfer sheet S has entered the secondary transfer nip portion. Since the leading edge of the transfer sheet S spreads the secondary transfer nip portion, load fluctuation occurs in the intermediate transfer belt 10 and the opposing roller 16, and the rotation of the opposing roller 16 is temporarily slowed. On the upstream side of the intermediate transfer belt rotation direction, the intermediate transfer belt 10 feels slack, and conversely, on the downstream side of the intermediate transfer belt, the intermediate transfer belt 10 becomes tight. Thus, the adjustment roller 31 provided on the upstream side with respect to a change in tension of the intermediate transfer belt 10 that causes the intermediate transfer belt 10 to loosen, for example, is adjusted from the reference position H to the H by the elastic force of the adjustment roller 31 itself. The outer peripheral position is changed to ', and the adjusting roller 30 provided on the downstream side similarly changes the outer peripheral position from the reference position G to G' by the elastic force of the adjusting roller 30 itself. By changing the outer peripheral positions of the adjustment rollers 30 and 31 in this way, it is possible to appropriately correct the tension of the intermediate transfer belt 10 so as not to loosen. Therefore, the transient load fluctuation that occurs when the transfer sheet S enters the secondary transfer nip portion affects the intermediate transfer belt 10 in the vicinity of the secondary transfer nip portion, but the intermediate transfer belt 10 is adjusted by the adjustment rollers 30 and 31. By adjusting the tension, the influence of the load fluctuation from the photosensitive drum 4 to the primary transfer portion where the image is transferred onto the intermediate transfer belt 10 is suppressed, in other words, the intermediate portion in the vicinity of the primary transfer portion. The speed fluctuation of the transfer belt 10 can be suppressed. Further, since the outer peripheral position of the adjustment rollers 30 and 31 is changed according to the change in tension of the intermediate transfer belt 10, this configuration does not adversely affect the belt drive system.

  Next, FIG. 16B shows a state where the transfer sheet S is separated from the secondary transfer nip portion. As the trailing edge of the transfer sheet S slips out of the secondary transfer nip, the pressure applied to the opposing roller 16 decreases transiently, so that the intermediate transfer belt 10 becomes tight on the upstream side as opposed to entering, and the above On the downstream side, the intermediate transfer belt 10 becomes loose. In accordance with such a change in the tension of the intermediate transfer belt 10, the adjustment roller 31 provided on the upstream side changes its outer peripheral position to H '' by the elastic force of the adjustment roller 31 itself, and is provided on the downstream side. Similarly, the adjusted roller 30 changes its outer peripheral position to G ″ by the elastic force of the adjusting roller 30 itself. By performing the above-described operation even when the transfer sheet S is separated from the secondary transfer nip portion in this way, the tension of the intermediate transfer belt 10 is not loosened due to the change in the outer peripheral position of the adjustment rollers 30 and 31. Since the correction is appropriately performed, it is possible to suppress the influence of the load fluctuation generated in the secondary transfer nip portion up to the primary transfer portion, in other words, the occurrence of the speed variation of the intermediate transfer belt 10 in the vicinity of the primary transfer portion. can do.

  Further, even when the low-quality transfer paper S is used by adjusting the tension of the intermediate transfer belt 10 by the adjustment rollers 30 and 31 according to the shape of the transfer paper S (such as unevenness of the paper surface). It is possible to prevent the load fluctuation from affecting the primary transfer portion, and it is possible to suppress deterioration in image quality.

  Compared with the transfer devices 90 of the configuration example 1 and the configuration example 2, the transfer device 90 of the configuration example 3 is 2 with respect to a transient load fluctuation caused by passing the transfer sheet S through the secondary transfer nip portion. There is no support member for supporting the two adjustment rollers 30 and 31, and the outer peripheral position of the adjustment roller 31 is changed by the elastic force of the adjustment rollers 30 and 31, respectively. It is possible to increase the response speed with respect to the generated tension change.

  Here, what demonstrated the structure of the adjustment rollers 30 and 31 is shown in FIG. Normally, the outer peripheral portion of the roller is made of a high-rigidity body, but the high-rigidity body is used only for the flange 86 at the end, and the roller is positioned here. In practice, the portion in contact with the intermediate transfer belt 10 is configured such that a flexible thin-film elastic member 87 is cylindrical and the flange 86 has a roller shape. A portion surrounded by the elastic member 87 and the flange 86 is filled with, for example, air or a rare gas. In addition, since the elastic force given to the adjustment rollers 30 and 31 having such a configuration is determined by the pressure of the gas to be filled, it is matched with the transient load fluctuation assumed in the transfer device 90 to which the adjustment rollers 30 and 31 are attached. Therefore, it is necessary to configure the adjusting rollers 30 and 31 by adjusting the pressure of the gas.

  The belt vibration frequency of the intermediate transfer belt 10 may differ depending on the configuration of the upstream side and the downstream side. In that case, it is necessary to adjust the elastic force of each of the adjusting rollers 30 and 31 in accordance with the belt vibration frequency, and the pressure of the gas to be filled is made different between the adjusting roller 30 and the adjusting roller 31 so that the pressure is suitable for each. This will be possible.

  18 and 19 show another configuration example of the adjustment rollers 30 and 31. FIG. A high-rigidity cylindrical member 88 is used on the outer periphery of the adjustment rollers 30 and 31, and elastic support members 89 having elasticity to support the cylindrical member 88 are provided at both inner ends of the cylindrical member 88. Further, in order to adjust the increase / decrease of the elastic force, the elastic support member 89 and the like can be freely arranged inside the cylindrical member 88 as shown in FIG. Is possible.

  As described above, according to the configuration example 3, a change in the tension of the intermediate transfer belt 10 due to the transient load fluctuation that occurs when the transfer sheet S is passed through the secondary transfer nip portion is caused in the secondary transfer nip portion. On the other hand, the adjustment rollers 30 and 31 provided on the upstream side and the downstream side appropriately change the outer peripheral positions of the adjustment rollers 30 and 31 by their own elastic force so that the intermediate transfer belt 10 does not become slack. Make adjustments. As a result, the intermediate transfer belt 10 is prevented from being loosened, and the influence of the load fluctuation on the primary transfer portion is suppressed, that is, the speed fluctuation of the intermediate transfer belt 10 in the vicinity of the primary transfer portion is suppressed. The intermediate transfer belt 10 can be driven with high accuracy, and image degradation caused by transient load fluctuations (speed fluctuations of the intermediate transfer belt 10) during image transfer onto the intermediate transfer belt 10 in the primary transfer portion. Can be suppressed. Further, since the adjustment rollers 30 and 31 are in contact with the back surface of the intermediate transfer belt 10, the adjustment rollers 30 and 31 do not contact the image carried on the front surface of the intermediate transfer belt 10, and the adjustment roller 30 and 31 do not disturb the image carried on the intermediate transfer belt 10.

As described above, according to the present embodiment, the intermediate transfer belt 10 that is a loop-shaped belt image carrier that is endlessly moved while being stretched by a plurality of stretching rollers, and the plurality of stretching belts via the intermediate transfer belt 10. The secondary transfer is a transfer roller that faces the counter roller 16 that is one of the rollers and abuts against the front surface that is the outer surface of the loop of the intermediate transfer belt 10 to form a secondary transfer nip portion that is a transfer nip. A transfer material which is a transfer material provided with a roller 33 and which is transferred from the surface to the front surface after being developed on the surface of the photosensitive drum 4 serving as a latent image carrier, and then sandwiched in the secondary transfer nip portion. In the transfer device 90 that transfers the image carried on the front surface to the paper S, the intermediate transfer belt 10 is upstream of the secondary transfer nip portion in the intermediate transfer belt rotation direction and downstream of the intermediate transfer belt rotation direction. Contact with the rear surface is a loop side has a tension adjusting means for adjusting the tension of the intermediate transfer belt 10 in accordance with a variation in tension of the intermediate transfer belt 10. Accordingly, it is possible to prevent the intermediate transfer belt 10 from becoming slack by adjusting the tension so that the tension is increased when the tension is smaller than a predetermined tension. Therefore, it is possible to prevent the intermediate transfer belt 10 from slackening due to the load fluctuation when the transfer paper S is passed through the secondary transfer nip, and the speed fluctuation from occurring in the intermediate transfer belt 10 near the primary transfer portion. . Therefore, it is possible to suppress the deterioration of the image quality caused by the speed fluctuation when the image is transferred from the photosensitive drum 4 to the intermediate transfer belt 10 at the primary transfer portion. Further, since the tension adjusting means is in contact with the back surface of the intermediate transfer belt 10, the tension adjusting means does not contact the image carried on the front surface of the intermediate transfer belt 10, and is carried on the intermediate transfer belt 10. Will not disturb the image.
Further, according to the present embodiment, the tension adjusting means includes the adjusting roller 21 that is the first contact member that contacts the back surface at the upstream side in the intermediate transfer belt rotation direction, and the adjustment roller 21 at the downstream side in the intermediate transfer belt rotation direction. The adjusting roller 20 is a second abutting member that contacts the back surface, and supporting means for supporting the adjusting rollers 20 and 21 so as to be displaceable, and the adjusting roller 20 according to a change in tension of the intermediate transfer belt 10. , 21 are displaced via the support means. Thereby, even if a transient load fluctuation occurs due to the transfer sheet S being passed through the secondary transfer nip portion, the adjustment rollers provided on the upstream side and the downstream side with respect to the secondary transfer nip portion. The tension of the intermediate transfer belt 10 can be adjusted by displacing 20 and 21 via the support means. Therefore, the intermediate transfer belt 10 is prevented from slacking and the influence of the load fluctuation on the primary transfer portion is suppressed, that is, the speed fluctuation of the intermediate transfer belt 10 in the vicinity of the primary transfer portion is suppressed, The intermediate transfer belt 10 can be driven with high accuracy, and image degradation due to transient load fluctuations (speed fluctuations of the intermediate transfer belt 10) during image transfer onto the intermediate transfer belt 10 at the primary transfer portion. It can be suppressed from occurring. Further, since the adjustment rollers 20 and 21 are in contact with the back surface of the intermediate transfer belt 10, the adjustment rollers 20 and 21 do not contact the image carried on the front surface of the intermediate transfer belt 10, and the adjustment roller 20 and 21 do not disturb the image carried on the intermediate transfer belt 10.
Further, according to the present embodiment, the support means includes a support member 23 that is a first support member that supports the adjustment roller 20, a support member 24 that is a second support member that supports the adjustment roller 21, and It is comprised by the holding member 22 which has the rotating shaft which can rotate with respect to an apparatus main body, and hold | maintains the supporting member 24 and the supporting member 24, and the adjusting roller 20 and the adjusting roller 21 support centering on the said rotating shaft. It is configured to be rotatable through the member 23 and the support member 24. As a result, the adjusting rollers 20 and 21 are displaced by the rotation of the holding member 22 according to the change in the tension of the intermediate transfer belt 10, and the tension of the intermediate transfer belt 10 can be appropriately corrected. Further, according to the present embodiment, the elastic member 32 is provided between the holding member 22 and the housing of the apparatus main body, and the holding member 22 is adjusted by being supported by the housing via the elastic member 32. The reference position of the rollers 20 and 21 can be determined, and vibration caused by the displacement of the adjustment rollers 20 and 21 can be reduced.
Further, according to the present embodiment, the transfer sheet S is subjected to the secondary transfer by providing the holding member 22 with the balance weight 25 that is a weight so that the adjustment roller 20 and the adjustment roller 21 maintain the equilibrium state at the reference position. It is possible to reinforce the action of the adjustment rollers 20 and 21 returning to the reference position after being separated from the nip portion, and to reliably return the adjustment rollers 20 and 21 to the reference position.
Further, according to the present embodiment, the support member 29 as the support means supports the adjustment roller 20 and the adjustment roller 21 so as to be slidable in parallel. As a result, the adjustment rollers 20 and 21 are displaced only by a linear motion, so that the number of parts can be reduced and a simple configuration is obtained. In addition, this reduces the inertial force of the adjustment mechanism itself, so that responsiveness to fluctuations can be improved.
Further, according to the present embodiment, at least a part of the support members 23, 24, and 29 is made of an elastic body, so that the necessary movements of the adjustment rollers 20 and 21 are performed, but undesirable vibrations that occur thereafter are generated. Since it can be absorbed by the elastic bodies of the support members 23, 24, and 29, a stable correction operation, that is, tension adjustment of the intermediate transfer belt 10 can be performed.
Further, according to this embodiment, at least one of the first contact member and the second contact member is the adjustment roller 20 or the adjustment roller 21 that is a roller member, so that the contact with the intermediate transfer belt 10 is achieved. The contact state can be easily kept good.
Further, according to the present embodiment, the surfaces of the first contact member and the second contact member that are in contact with the intermediate transfer belt 10 have a predetermined curvature. As a result, the first contact member and the second contact member can smoothly contact the intermediate transfer belt 10 and the contact state can be kept good. Further, in particular, the contact member is configured to have a saddle shape having a predetermined curvature in the shape of the portion in contact with the intermediate transfer belt 10 so that the contact member smoothly contacts the roller member. Inertia can be reduced as compared with the case of using, and responsiveness is improved with respect to the case where the change in tension of the intermediate transfer belt 10 due to the load fluctuation is small.
Further, according to the present embodiment, the tension adjusting means includes the adjusting roller 31 that is a first contact elastic member having elasticity that contacts the back surface upstream of the intermediate transfer belt rotation direction, and the intermediate transfer belt rotation. The adjustment roller 30 is a second elastic contact member that is in contact with the back surface on the downstream side in the direction, and the adjustment rollers 30 and 31 are deformed in accordance with a change in the tension of the intermediate transfer belt 10. The outer peripheral position of the adjustment rollers 30 and 31 is changed. As a result, the tension change of the intermediate transfer belt 10 due to the transient load fluctuation that occurs when the transfer sheet S is passed through the secondary transfer nip portion can be detected in the upstream side and the upstream side with respect to the secondary transfer nip portion. The adjustment rollers 30 and 31 provided on the downstream side change the outer peripheral positions of the adjustment rollers 30 and 31 by their own elastic force, so that the intermediate transfer belt 10 can be appropriately adjusted so that the intermediate transfer belt 10 is not loosened. Therefore, the intermediate transfer belt 10 is prevented from slacking and the influence of the load fluctuation on the primary transfer portion is suppressed, that is, the speed fluctuation of the intermediate transfer belt 10 in the vicinity of the primary transfer portion is suppressed, The intermediate transfer belt 10 can be driven with high accuracy, and image degradation due to transient load fluctuations (speed fluctuations of the intermediate transfer belt 10) during image transfer onto the intermediate transfer belt 10 at the primary transfer portion. It can be suppressed from occurring. Further, since the adjustment rollers 30 and 31 are in contact with the back surface of the intermediate transfer belt 10, the adjustment rollers 30 and 31 do not contact the image carried on the front surface of the intermediate transfer belt 10, and the adjustment roller 30 and 31 do not disturb the image carried on the intermediate transfer belt 10.
In addition, according to the present embodiment, the adjustment roller 30 and the adjustment roller 31 have an elastic portion at a portion in contact with the intermediate transfer belt 10, and the elastic portion is a flexible thin-film elastic member that is a flexible thin member. The member is formed in a cylindrical shape and encloses gas therein. Thereby, it adjusts easily by changing the pressure of the gas which fills the elastic force which the adjustment rollers 30 and 31 have in accordance with the transient load fluctuation assumed with the transfer device 90 to which the adjustment rollers 30 and 31 are attached. be able to.
According to the present embodiment, at least one of the first contact elastic member and the second contact elastic member is the adjustment rollers 30 and 31 that are roller members, and the adjustment rollers 30 and 31 are hollow cylinders. A cylindrical member 81, which is a rigid member having a high rigidity, and an elastic support member 82 having elasticity for supporting the cylindrical member 81 inside the hollow cylinder of the cylindrical member 81, It is possible to adjust the magnitude of the elastic force.
Further, according to the present embodiment, the elastic modulus of the adjustment roller 30 and that of the adjustment roller 31 are different, so that it is possible to cope with the belt vibration frequency being different depending on the configuration of the upstream side and the downstream side. .
Further, according to the present embodiment, the photosensitive drum 4 that is a latent image carrier that carries a latent image, and the developing unit that develops the latent image carried on the photosensitive drum 4 to obtain a visible image. In a copying machine, which is an image forming apparatus provided with an apparatus and a transfer unit that transfers a visible image on the photosensitive drum 4 to a transfer sheet S that is a sheet member, the transfer device 90 of the present invention is used as the transfer unit. As a result, it is possible to prevent the intermediate transfer belt 10 from slackening due to the load fluctuation when the transfer paper S is passed through the secondary transfer nip, and the speed fluctuation from occurring in the intermediate transfer belt 10 near the primary transfer portion. it can. Therefore, it is possible to suppress the deterioration of the image quality caused by the speed fluctuation when the image is transferred from the photosensitive drum 4 to the intermediate transfer belt 10 at the primary transfer portion. Further, since the tension adjusting means is in contact with the back surface of the intermediate transfer belt 10, the tension adjusting means does not contact the image carried on the front surface of the intermediate transfer belt 10, and is carried on the intermediate transfer belt 10. Will not disturb the image. Therefore, image formation can be performed with good image quality.

FIG. 2 is a schematic configuration diagram of a transfer device according to Configuration Example 1; 1 is a schematic configuration diagram of a copier according to an embodiment. 1 is a schematic configuration diagram showing a basic configuration of a transfer apparatus according to an embodiment. Explanatory drawing when a streaky dark part and a thin part are made in the formed image with the transient load fluctuation. FIG. 6 is a schematic configuration diagram when the rotation path of the intermediate transfer belt is changed when the transfer paper enters the secondary transfer nip portion. FIG. 4 is a schematic configuration diagram when feedback control is performed using a rotation angle or angular velocity of a counter roller with respect to an intermediate transfer belt. (A) The figure which shows a state when a transfer paper rushes into a secondary transfer nip part. FIG. 6B is a diagram illustrating a state when the transfer paper is detached from the secondary transfer nip portion. The schematic block diagram at the time of providing a balance weight in a holding member. The schematic block diagram at the time of providing an elastic member in a part of support member. The schematic block diagram at the time of providing an elastic member between a holding member and the housing | casing of an apparatus main body. FIG. 6 is a schematic configuration diagram of a transfer device according to Configuration Example 2. (A) The figure which shows a state when the transfer paper S rushes into a secondary transfer nip part. FIG. 6B is a diagram illustrating a state when the transfer sheet S is detached from the secondary transfer nip portion. The schematic block diagram at the time of providing an elastic member in a part of support member. (A) The figure at the time of using a general roller for an abutting member. (B) The figure at the time of using the roller which lowered the inertia for the contact member. (C) The case where the shape of the part which contact | connects an intermediate transfer belt is used for a contact member as a saddle type. FIG. 10 is a schematic configuration diagram of a transfer apparatus according to Configuration Example 3. (A) The figure which shows a state when a transfer paper rushes into a secondary transfer nip part. FIG. 6B is a diagram illustrating a state when the transfer paper is detached from the secondary transfer nip portion. The schematic block diagram of the adjustment roller which acquires elastic force with the pressure of gas. The perspective view of an adjustment roller at the time of comprising an adjustment roller by the highly rigid cylindrical member and the elastic member which supports a cylindrical member inside a cylindrical member. Sectional drawing of an adjustment roller at the time of comprising an adjustment roller by the highly rigid cylindrical member and the elastic member which supports a cylindrical member inside a cylindrical member. FIG. 6 is a state diagram showing a state in which the intermediate transfer belt is slackened when the transfer paper enters the secondary transfer nip portion. FIG. 6 is a state diagram illustrating a state where the intermediate transfer belt is slackened when the transfer paper is separated from the secondary transfer nip portion.

Explanation of symbols

4 Photosensitive drum 10 Intermediate transfer belt 16 Opposed roller 20 Adjustment roller 21 Adjustment roller 22 Holding member 23 Support member 24 Support member 25 Balance weight 26 Elastic member 27 Elastic member 28 Elastic member 29 Support member 30 Adjustment roller 31 Adjustment roller 32 Elastic member 33 Secondary transfer roller 81 Roller member 82 Support member 83 Fixed member 84 Rotating cylinder 85 Contact member 86 Flange 87 Elastic member 88 Cylindrical member 89 Elastic support member 90 Transfer device

Claims (14)

A loop-shaped belt image carrier that is endlessly moved while being stretched by a plurality of stretching rollers;
A transfer roller that faces one of the plurality of stretching rollers via the belt image carrier and abuts against a front surface that is an outer surface of the loop of the belt image carrier to form a transfer nip;
In a transfer device for transferring an image developed on the surface of a latent image carrier from the surface to the front surface and then transferring the image carried on the front surface to a transfer material sandwiched in the transfer nip ,
With respect to the transfer nip, the belt image carrier is in contact with the back surface, which is the inner surface of the loop of the belt image carrier, on the upstream side in the rotation direction of the belt image carrier and on the downstream side of the belt image carrier. A transfer apparatus comprising tension adjusting means for adjusting the tension of the belt image carrier. The transfer device according to claim 1.
The tension adjusting means includes a first contact member that contacts the back surface at the upstream side in the belt image carrier rotation direction and a second contact member that contacts the back surface at the downstream side in the belt image carrier rotation direction. And a supporting means for supporting the first abutting member and the second abutting member in a displaceable manner,
A transfer apparatus, wherein the first contact member and the second contact member are displaced via the support means in accordance with a change in tension of the belt image carrier. The transfer device according to claim 2.
The support means includes a first support member that supports the first contact member, a second support member that supports the second contact member, and a rotation shaft that is rotatable with respect to the apparatus main body. A holding member that holds the first support member and the second support member;
The transfer device, wherein the first contact member and the second contact member are rotatable about the rotation axis via the first support member and the second support member. . The transfer device according to claim 3.
An elastic member is provided between the holding member and the housing of the apparatus main body,
The transfer apparatus, wherein the holding member is supported by the housing via the elastic member. The transfer device according to claim 3 or 4,
The holding member is provided with a weight, and the first contact member and the second contact member displaced from a predetermined reference position return to the predetermined reference position by gravity acting on at least the weight. A transfer device characterized by that. The transfer device according to claim 2.
The support means is slidable in a linear direction passing through the first contact member and the second contact member;
The transfer device, wherein the first contact member and the second contact member are displaceable in the linear direction via the support means. The transfer device according to claim 1, 2, 3, 4, 5 or 6.
A transfer apparatus characterized in that at least a part of the support means is made of an elastic body. The transfer device according to claim 1, 2, 3, 4, 5, 6 or 7.
At least one of the first contact member and the second contact member is a roller member. The transfer device according to claim 1, 2, 3, 4, 5, 6 or 7.
The transfer device, wherein surfaces of the first contact member and the second contact member that are in contact with the belt image carrier are curved surfaces having a predetermined curvature. The transfer device according to claim 1.
The tension adjusting means includes an elastic first contact elastic member that contacts the back surface at the upstream side in the rotation direction of the belt image carrier, and an elastic member that contacts the back surface at the downstream side in the rotation direction of the belt image carrier. A second abutting elastic member having
A transfer device, wherein the first contact elastic member and the second contact elastic member are deformed in accordance with a change in tension of the belt image carrier. The transfer device according to claim 10.
The first abutting elastic member and the second abutting elastic member have an elastic portion in a portion that abuts on the belt image carrier.
The transfer device is characterized in that the elastic portion is configured by wrapping a predetermined gas with a flexible thin-walled member. The transfer device according to claim 10.
At least one of the first contact elastic member and the second contact elastic member is a roller member,
The roller device includes a rigid member having a hollow cylindrical shape and high rigidity, and an elastic support member having elasticity for supporting the rigid member inside the hollow cylinder of the rigid member. The transfer device according to claim 10, 11 or 12,
A transfer apparatus, wherein the first contact elastic member and the second contact elastic member have different elastic moduli. A latent image carrier for carrying a latent image;
Developing means for developing a latent image carried on the latent image carrier to obtain a visible image;
In an image forming apparatus comprising transfer means for transferring a visible image on a latent image carrier to a sheet member,
An image forming apparatus using the transfer device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 as the transfer means.

Images