JP2007241013A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of removing contamination on the contact part of a bias application member and intermediate transfer body, capable of retaining a satisfactory transfer rate such that the resistance value of the contact part stabilizes with lapse of time and a change in transfer electric field is less, and also capable of preventing image defects such as dust and middle missing. <P>SOLUTION: The image forming apparatus vibrates the bias application member, thereby removing contamination between the intermediate transfer body 2 and the bias application member. A cleaning member is passed through the contact part of the intermediate transfer body 2 and bias application member, thereby removing the contamination. The contamination on the contact part of the intermediate transfer body 2 and bias application member is removed by causing the intermediate transfer body 2 to rotate in the reverse direction to that used for regular image formation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a laser color printer or a copier. Furthermore, the present invention relates to a color electrophotographic image forming apparatus using an intermediate transfer member having a bias applying device.

2. Description of the Related Art Today, electrophotographic apparatuses are increasing in color, such as color copiers and color printers, according to market demands.
A color electrophotographic apparatus is provided with a developing device of a plurality of colors around one photosensitive member, and a toner is attached to the developing device to form a composite toner image on the photosensitive member, and the toner image is transferred. A so-called revolver type that records a color image on a sheet, and a plurality of photoconductors arranged side by side are each provided with a developing device, and a single color toner image is formed on each photoconductor, and the single color toner images are sequentially formed. There is a so-called tandem type that transfers and records a composite color image on a sheet.
Comparing the revolver type and the tandem type, the former has only one photoconductor, so that there is an advantage that the size can be reduced relatively and the cost can be reduced. Times) Since full-color images are formed by repeating image formation, there is a drawback that speeding up image formation is limited, while the latter has the disadvantage of increasing the size and cost, but speeding up image formation There is an advantage that can be realized.

Recently, however, tandem-type devices have been attracting attention because full-color and monochrome-like speeds are desired.
The tandem type electrophotographic apparatus includes a direct transfer system in which images on each photoconductor are sequentially transferred to a sheet conveyed by a sheet conveying belt by a transfer device, and an image on each photoconductor by a primary transfer device. There is an indirect transfer type in which images are sequentially transferred to an intermediate transfer member and then transferred onto a sheet by a secondary transfer device.
Comparing the direct transfer type and the indirect transfer type, the former requires that a paper feeding device is arranged upstream of the tandem image forming apparatus in which the photoconductors are arranged, and a fixing device is arranged downstream. , There is a drawback of increasing the size. On the other hand, since the latter can set the secondary transfer position relatively freely, the paper feeding device and the fixing device can be arranged so as to overlap the tandem type image forming device, and the size can be reduced. There are advantages.
In the former, since the fixing device is disposed close to the tandem image forming apparatus so as not to increase the size, the fixing device cannot be disposed with a sufficient margin that the sheet can be bent. There is a drawback that the fixing device affects the image formation on the rear end side due to an impact when the leading edge of the toner enters the fixing device or a difference in sheet conveyance speed when passing through the fixing device. On the other hand, in the latter case, since the fixing device can be arranged with a sufficient margin that the sheet can bend, the fixing device can hardly affect the image formation.
For these reasons, attention has recently been paid to the indirect transfer type among tandem type electrophotographic apparatuses. In this type of color electrophotographic apparatus, the transfer residual toner remaining on the photoconductor after the primary transfer is removed by a photoconductor cleaning device to clean the surface of the photoconductor to prepare for another image formation. Further, the transfer residual toner remaining on the intermediate transfer member after the secondary transfer is removed by an intermediate transfer member cleaning device to clean the surface of the intermediate transfer member to prepare for another image transfer.

In the intermediate transfer body system, each color toner image is sequentially transferred onto the intermediate transfer body. In the process of transferring the second and subsequent colors to the intermediate transfer system, a “reverse transfer” phenomenon may occur in which the toner in the previous process returns from the intermediate transfer member to the photosensitive member. This is an electrophotographic industry term and is known as “reverse transfer” or “retransfer”.
Although this phenomenon is usually improved by lowering the transfer bias, there is a problem that the toner transfer rate for the second and subsequent colors cannot be increased. Originally, “transfer residual” occurs when the transfer bias is not sufficiently increased. Therefore, “reverse transfer” and “remaining transfer” are in a trade-off, and the person in charge adjusts the “remaining transfer” reduction or “reverse transfer” reduction in consideration of the trade-off relationship. Since such adjustment is very fine, for example, it varies due to slight fluctuations in the potential of the transfer belt or the photoconductor, which is a cause of variations in the transfer performance of the machine.
Incidentally, the cause of “reverse transfer” is a discharge in the vicinity of the primary transfer nip. This discharge causes positive and negative ions to disperse, which directly causes the toner to accept and fluctuate the charge amount. When this discharge occurs, the image quality also deteriorates.
From the above, it is important to perform transfer by applying a sufficient transfer electric field, and further reduce excessive discharge.To reduce both transfer residue and reverse transfer, a bias application device is installed at the entrance and exit of the transfer nip. It is important to apply an electric field by the same polarity bias as the toner polarity.
However, such a measure is difficult for a machine having a small primary transfer nip. First, layout design is quite difficult to arrange electrodes densely in a narrow place. Moreover, if the adjacent electrodes are not reliably insulated, a large amount of leakage current flows, which is clearly problematic in terms of power supply specifications.

Further, almost all current intermediate transfer belts are made conductive by kneading carbon or the like into a polymer, and since they are electronic conductive resistors, the resistance is electric field dependent. When such an intermediate transfer belt is used, the resistance is low in the primary transfer, but the resistance increases as it leaves the primary transfer nip. The transfer bias charge remaining in the belt moves when the resistance is low, but in this case, the charge is increased by increasing the resistance, and thus an air discharge may be generated when the gap is widened when the intermediate transfer belt is peeled off. . Due to the occurrence of this discharge, reverse-polarity ions are generated and sucked into the image toner, causing the polarity to vary, and even after the transfer nip, the toner is irregularly shaken, resulting in worsening of dust. In addition, since the toner Q / M of the surface layer is changed with respect to the solid, the transfer rate is lowered.
Therefore, when using a belt having a high resistance when no electric field is applied, it is required to reduce the primary discharge outlet discharge. Therefore, for example, Patent Document 1 discloses an image forming apparatus in which an electrode is placed on the downstream side considerably away from the nip. However, this method has a problem in that electric charges often remain in a belt having a large capacity and high electric field dependency.
There are two possible reasons for this. First, even if a counter bias is applied to the exit peeling location as in Patent Document 2, an intermediate transfer belt having high voltage dependency of resistance loses electric field application and at the same time increases resistance. The current to the potential portion that has been neutralized is also reduced, and a current that lowers the belt potential cannot flow. In this case, it is considered that charge removal is insufficient because charge removal is performed at the outlet of the mechanical nip. Second, the residual charge remaining in the medium resistance member tends to remain in the interior even after the neutralization of the surface is completed. In order to remove this, it is preferable to use AC charge discharge, but it is difficult to remove electricity by DC charge or the like. In such a case, the static elimination time is important. Here, since the static elimination is performed at the outlet end of the mechanical nip, the static elimination time is insufficient.
As described above, there has been a desire to prevent the residual charge obtained by the belt in the nip before discharging from the primary transfer, so that there is no shortage of charge and no image abnormality is caused thereby. . In particular, stability against electrode contamination over time has been desired.

JP 2003-57963 A Japanese Patent No. 3346063

  Therefore, the present invention has been made in view of the above-mentioned problems, and the problem is that the contamination of the contact portion between the bias applying member and the intermediate transfer member can be removed, and the resistance value of the contact portion is stabilized over time. It is an object of the present invention to provide an image forming apparatus that can maintain a good transfer rate with little change in electric field and can prevent abnormal images such as dust and voids.

The features of the present invention, which is a means for solving the above problems, are listed below.
The present invention includes an image carrier that is rotated with a toner image formed on the surface, a belt-shaped intermediate transfer member that rotates in the same direction while being in contact with the image carrier, and transfers the toner image from the image carrier; A plurality of bias applying members which are opposite to the image bearing member with respect to the intermediate transfer member and apply a bias having the same polarity as that of the toner at the upstream position and the downstream position; and a toner in a region sandwiched between the plurality of bias applying members A transfer station including a bias application member that applies a reverse polarity bias, and a cleaning member that removes at least a part of the bias application member that provides the same polarity as the toner and dirt on the bias application member that provides the reverse polarity to the toner. An image forming apparatus comprising: an image forming apparatus having a structure in which dirt between the intermediate transfer member and the bias applying member is removed by vibrating the bias applying member. . Here, the bias applying member includes a bias blade and a bias roller, and the image carrier includes a photoconductor.
The present invention is characterized in that the cleaning member vibrates before a predetermined job ends and the intermediate transfer member stops.
The present invention is characterized in that excitation is performed by ultrasonic waves.
The present invention includes an image carrier that is rotated with a toner image formed on the surface, a belt-shaped intermediate transfer member that rotates in the same direction while being in contact with the image carrier, and transfers the toner image from the image carrier; A plurality of bias applying members which are opposite to the image bearing member with respect to the intermediate transfer member and apply a bias having the same polarity as that of the toner at the upstream position and the downstream position; and a toner in a region sandwiched between the plurality of bias applying members A transfer station including a bias application member that applies a reverse polarity bias, and a cleaning member that removes at least a part of the bias application member that provides the same polarity as the toner and dirt on the bias application member that provides the reverse polarity to the toner. In the image forming apparatus, the cleaning member removes dirt by passing through a contact portion between the intermediate transfer member and the bias applying member. It is.
The present invention is characterized in that the cleaning member performs a cleaning operation after a predetermined job is completed and the intermediate transfer member is stopped.
The present invention includes an image carrier that is rotated with a toner image formed on the surface, a belt-shaped intermediate transfer member that rotates in the same direction while being in contact with the image carrier, and transfers the toner image from the image carrier; A plurality of bias applying members which are opposite to the image bearing member with respect to the intermediate transfer member and apply a bias having the same polarity as that of the toner at the upstream position and the downstream position; and a toner in a region sandwiched between the plurality of bias applying members A transfer station including a bias application member that applies a reverse polarity bias, and a cleaning member that removes at least a part of the bias application member that provides the same polarity as the toner and dirt on the bias application member that provides the reverse polarity to the toner. In the image forming apparatus, the intermediate transfer member rotates in the reverse direction to that during normal image formation to remove contamination on the contact portion between the intermediate transfer member and the bias applying member. A forming apparatus.
The present invention is characterized in that the intermediate transfer member rotates in the reverse direction for a predetermined time after the predetermined job ends and the image forming unit stops.

  According to the present invention, the means for solving the problem can remove the contamination at the contact portion between the bias applying member and the intermediate transfer member, the resistance value of the contact portion is stable over time, and the change in the transfer electric field is small. Can be maintained, and an image forming apparatus capable of preventing abnormal images such as dust and voids can be provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

Based on FIG. 1, the configuration and operation outline of a tandem type color copier as an image forming apparatus in the present embodiment will be described.
The color copying machine 1 includes an image forming unit 1A positioned at the center of the apparatus main body, a paper feeding unit 1B positioned below the image forming unit 1A, a document conveying unit 1C positioned above the image forming unit 1A, And a scanner unit.
An intermediate transfer belt 2 as an intermediate transfer body having a transfer surface extending in the horizontal direction is disposed in the image forming unit 1A. The upper surface of the intermediate transfer belt 2 has a color complementary to the color separation color. A configuration for forming an image is provided. That is, the photoreceptors 3Y, 3M, 3C, and 3B as image carriers capable of carrying an image of toners of complementary colors (yellow, magenta, cyan, and black) are juxtaposed along the transfer surface of the intermediate transfer belt 2. Has been.
Each of the photoconductors 3Y, 3M, 3C, and 3B is configured by a drum that can rotate in the same direction (counterclockwise direction), and around the charging device 4 that performs image forming processing in the rotation process, light A writing device 5, a developing device 8, a primary transfer device 7, and a cleaning device 6 are arranged as writing means. The alphabet added to each symbol corresponds to the color of the toner as in the photosensitive member 3. In FIG. 1, symbols are added to the charging device 4Y, developing device 8Y, primary transfer device 7Y, and cleaning device 6Y corresponding to yellow, but the same applies to other color devices. 5Y indicates the writing light of the yellow toner image. Each developing device 8 contains respective color toners. The intermediate transfer belt 2 has a configuration that is wound around the driving roller 2B and the driven roller 2A and can move in the same direction at a position facing the photoconductors 3Y, 3M, 3C, and 3B. A cleaning device 10 for cleaning the surface of the intermediate transfer belt 2 is provided at a position facing the driven roller 2A.

The surface of the photoreceptor 3Y is uniformly charged by the charging device 4Y, and an electrostatic latent image is formed on the photoreceptor 3Y based on image information from the scanner unit. The electrostatic latent image is visualized as a toner image by a developing device 8Y containing yellow toner, and the toner image is primarily transferred onto the intermediate transfer belt 2 by a primary transfer device 7Y to which a predetermined bias is applied. The The other photoconductors 3M, 3C, and 3B also form similar images only with different toner colors, and the toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 2 and superimposed. The toner remaining on the photosensitive member 3 after the transfer is removed by the cleaning device 6, and the potential of the photosensitive member 3 is initialized by a neutralizing lamp (not shown) after the transfer to prepare for the next image forming process.

The paper feed unit 1B includes a paper feed tray 1B1 for stacking and storing paper P as a recording medium, and a paper feed roller for separating and feeding the paper P in the paper feed tray 1B1 one by one from the top. The conveyance roller pair 1B2 that conveys the fed paper P and the paper P are temporarily stopped and the oblique deviation is corrected, and then the leading edge of the image on the intermediate transfer belt 2 coincides with a predetermined position in the conveyance direction. It has a registration roller pair 1B3 that is sent out toward the nip N at timing. A sensor (not shown) for detecting the reflectance of the paper surface is provided in the vicinity of the registration roller pair 1B3. When the value is different from the sensor output in the previous process, the intermediate transfer belt 2 or the opposing roller 2C is switched.

A toner image T (hereinafter, also simply referred to as “toner”) primarily transferred from the photoreceptors 3Y, 3M, 3C, 3B onto the intermediate transfer belt 2 is biased (AC, pulse, etc.) by a secondary transfer bias applying unit (not shown). Is applied to the opposing roller 2C and is secondarily transferred onto the paper P by the action of an electric field between the secondary transfer roller 9B and the intermediate transfer belt 2.
Thereafter, the sheet P on which the toner image T is secondarily transferred on the surface is firmly fixed on the surface by the action of heat and pressure in the fixing device 11.

The detailed configuration and operation of the primary transfer unit of the image forming apparatus according to this embodiment will be described with reference to FIGS.
FIG. 2 is an explanatory diagram of operations and operations in the configuration of the first embodiment in which cleaning is performed by oscillating the bias blade, which is a bias applying member, and the bias blade. FIG. 3 is an explanatory diagram of operations and operations in the configuration of the second embodiment in which cleaning is performed by passing a cleaning member between the intermediate transfer belt, the transfer bias blade, and the bias blade.
FIG. 4 is an explanatory diagram of operations and operations in the configuration of the fourth embodiment in which cleaning is performed by rotating the intermediate transfer belt in the reverse direction after a predetermined job is completed.

In the present invention, in order to move the toner image formed on the toner photoreceptor 3 onto the intermediate transfer belt 2 without disturbing the toner charge, the toner charge and the toner charge before and after the transfer bias blade 71 to which the reverse polarity to the toner charge is applied. A bias roller 73 and a bias blade 72 are arranged as a plurality of bias members to which the same polarity is applied. A toner image (not shown) formed on the photoreceptor 3 is transferred onto the intermediate transfer belt 2. The toner image is affected by the potential of the intermediate transfer belt 2 as it approaches the intermediate transfer belt. In order to faithfully transfer the toner image on the photoreceptor 3 onto the intermediate transfer belt 2, it is necessary to prevent “pre-transfer” that is transferred at a position before the transfer nip due to the potential of the intermediate transfer belt 2. . Therefore, in the embodiment of the present invention, the surface potential of the intermediate transfer belt 2 is set to the same polarity (−) as that of the toner by the entrance side (−) bias roller 73 provided on the inner surface of the intermediate transfer belt before entering the transfer process. The toner image is prevented from moving and degrading the image quality. In the transfer nip, (−) toner is transferred from the photoreceptor 3 to the intermediate transfer belt 2 in the mechanical contact nip constituted by the photoreceptor 3 and the intermediate transfer belt 2 by the (+) transfer bias blade 71. After that, the (+) potential of the intermediate transfer belt 2 is dropped to near 0 V by the exit side (−) bias blade 72 on the back surface of the intermediate transfer belt 2, and this occurs due to a potential difference when the photosensitive member 3 and the intermediate transfer belt 2 are peeled off. The discharge phenomenon is prevented.

FIG. 2 is an explanatory diagram of Example 1 of the primary transfer portion in the present invention.
In Example 1, an ultrasonic wave generating element is provided at the end of a blade holder 74 that holds a plurality of blades of the transfer bias blade 71 and the outlet side (−) bias blade 72, and the print job is completed. When the ultrasonic transfer element is energized while rotating the intermediate transfer belt 2 for a predetermined time later, the contact interface between the bias blades 71 and 72 and the intermediate transfer belt 2 is vibrated, and the dirt accumulated on the interface rises. The blades 71 and 72 are easily detached from the tip.
The timing of applying the ultrasonic vibration may be performed every time when all the jobs are completed. However, since the traveling time and the traveling distance of the intermediate transfer belt 2 become very long, it is desirable that each time the print job is performed several times. It is better to shake once. As a specific embodiment, if dirt accumulates between the blades 71 and 72 and the intermediate transfer belt 2, the voltage-current characteristics in the primary transfer change, so that immediately after a certain threshold is exceeded. There is a system that performs cleaning when the job is completed.
As a result, the contamination of the contact portion between the bias blades 71 and 72 and the intermediate transfer body 2 can be removed by oscillating the bias blades 71 and 72, so that the resistance value of the contact portion is stabilized over time and the transfer electric field changes. Therefore, a good transfer rate can be maintained, and abnormal images such as dust and voids can be prevented. Further, the maximum cleaning effect can be obtained with a minimum operation without affecting the image. Since the contamination of the contact portion between the bias blades 71 and 72 and the intermediate transfer member 2 can be removed, the resistance value of the contact portion is stabilized with time, the change in the transfer electric field is small, a good transfer rate can be maintained, and dust and voids can be maintained. Such an abnormal image can be prevented.
Further, the maximum cleaning effect can be obtained with a minimum operation without affecting the image. Since the contamination of the contact portion between the bias blades 71 and 72 and the intermediate transfer member 2 can be removed, the resistance value of the contact portion is stabilized with time, the change in the transfer electric field is small, a good transfer rate can be maintained, and dust and voids can be maintained. Such an abnormal image can be prevented.

FIG. 3 is an explanatory diagram of Example 2 of the primary transfer portion in the present invention.
In the second embodiment, cleaning is performed by passing a cleaning member between a plurality of blades of the intermediate transfer belt 2, the transfer bias blade 71, and the outlet side (−) bias blade 72. In the present invention, since the transfer bias is applied by the blade, when the cleaning member is passed between the intermediate transfer belt 2 and the transfer bias blade 71, the transfer bias blade 71 is deformed and escapes. 2 and the damage to the transfer bias blade 71 are not particularly problematic. Specific examples of the configuration of the cleaning member include a member 78 in which a non-woven fabric is attached around the metal plate 77, or a member 78 in which a non-woven fabric is wound around a wire such as a wire. The cleaning member performs cleaning by moving from the position indicated by 76a in FIG. 3 to the position indicated by 76b. When one cleaning process is completed, the cleaning member goes around the blade holder 74 and prepares for the next cleaning process again at a position indicated by 76a. The timing for passing the cleaning member between the intermediate transfer belt 2 and the bias blades 71 and 72 may be performed every time when all jobs are completed. However, the travel time and travel distance of the intermediate transfer belt 2 become very long. Therefore, it is desirable to perform the cleaning process once every several print jobs. As a specific example, when dirt accumulates between the bias blades 71 and 72 and the intermediate transfer belt 2, the voltage-current characteristic in the primary transfer changes, so that a certain threshold is exceeded. There is a system that performs cleaning when the immediately following job is completed.
As a result, dirt at the contact portion between the bias blades 71 and 72 and the intermediate transfer member 2 can be removed, so that the resistance value at the contact portion is stable over time, the change in the transfer electric field is small, and a good transfer rate can be maintained. And abnormal images such as omissions can be prevented. Further, the maximum cleaning effect can be obtained with a minimum operation without affecting the image. Since the contamination of the contact portion between the bias blades 71 and 72 and the intermediate transfer member 2 can be removed, the resistance value of the contact portion is stabilized with time, the change in the transfer electric field is small, a good transfer rate can be maintained, and dust and voids can be maintained. Such an abnormal image can be prevented.

FIG. 4 is an explanatory diagram of Example 3 of the primary transfer portion in the present invention.
In the third embodiment, the intermediate transfer belt 2 is temporarily rotated in the direction opposite to the rotation direction at the time of normal image formation, whereby a plurality of intermediate transfer belt 2, transfer bias blade 71, and outlet side (−) bias blade 72 are provided. Dirt can be removed from the blade contact portion. Specifically, as shown in FIG. 4, the position of the suspension roller 79 such as a drive roller or a tension roller is lowered to move the position of the intermediate transfer belt 2 from the first position during normal operation (broken line in the figure) to the photosensitive member 3. The intermediate transfer belt 2 rotates in the reverse direction after moving to a second position (solid line in the figure) that does not come into contact with the photosensitive member 3, and the units around the photosensitive member such as the photosensitive member 3 and a developing device (not shown) are stopped. When the intermediate transfer belt 2 is pushed down, the entrance side (−) bias roller 73 overcomes the force of a pressing spring (not shown) and falls downward, and the bias blades 71 and 72 are also bent downward due to elasticity. By rotating in the reverse direction, dirt can be removed from the contact portion between the intermediate transfer belt 2 and the bias blades 71 and 72. The intermediate transfer belt 2 may be rotated at the timing of reverse rotation of the intermediate transfer belt 2 from the position during normal operation every time when all jobs are completed. However, the travel time and travel distance of the intermediate transfer belt 2 are very long. As a result, a load is applied to the tip portions of the bias blades 71 and 72. Therefore, it is desirable to perform the cleaning process once every several print jobs. As a specific example, when dirt accumulates between the bias blades 71 and 72 and the intermediate transfer belt 2, the voltage-current characteristic in the primary transfer changes, so that a certain threshold is exceeded. There is a system that performs cleaning when the immediately following job is completed.
As a result, the contact portion between the bias blades 71 and 72 and the intermediate transfer member 2 is released for a moment by returning to the reverse direction after the intermediate transfer member is stopped, so that dirt can be removed, the resistance value is stabilized over time, and the transfer electric field is transferred. Change, the transfer rate can be maintained, and abnormal images such as dust and voids can be prevented. Further, the maximum cleaning effect can be obtained with a minimum operation without affecting the image. Since the contamination of the contact portion between the bias blades 71 and 72 and the intermediate transfer member 2 can be removed, the resistance value of the contact portion is stabilized with time, the change in the transfer electric field is small, a good transfer rate can be maintained, and dust and voids can be maintained. Such an abnormal image can be prevented.

As specific operation examples for determining the cleaning timing in the first to third embodiments of the present invention, the contact between the (+) transfer bias blade 71 and the exit side (−) bias blade 72 and the intermediate transfer belt 2 is described. While detecting the deterioration of the state, the current or voltage flowing between the (+) transfer bias blade 71 and the outlet side (−) bias blade 72 and the intermediate transfer belt 2 is detected, and a judgment is made based on a predetermined threshold value to perform cleaning. There is a means to determine timing. When it is determined that the contact state has deteriorated, vibration is applied to the pair of the (+) transfer bias blade 71 and the exit side (−) bias blade 72, or the intermediate transfer belt 2 and the (+) transfer bias blade 71, Then, the cleaning member is passed between the outlet side (−) bias blade 72 or the intermediate transfer belt 2 is rotated in the direction opposite to the normal image forming operation direction.
In addition, when the predetermined threshold value is not satisfied even if the cleaning operation is repeatedly performed by this method, the service man call is displayed and the transfer bias blade 71 or the outlet side (-) bias blade 72 is replaced as a service part. Therefore, it is possible to prevent a fatal failure such as deterioration of the photosensitive member 3 or the surface of the intermediate transfer belt member 2 due to abnormal discharge or the like.

1 is a diagram illustrating an image forming apparatus according to an exemplary embodiment. It is explanatory drawing of Example 1 of the primary transfer part in this invention. It is explanatory drawing of Example 2 of the primary transfer part in this invention. It is explanatory drawing of Example 3 of the primary transfer part in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color copier 1A Image formation part 1B Paper feed part 1B1 Paper feed tray 1B2 Conveyance roller pair 1B3 Registration roller pair 1C Document conveyance part 2 Intermediate transfer belt 2A Driven roller 2B Drive roller 2C Opposite roller 3 Photoconductor 4 Charging device 5 Writing device 6 Cleaning device 7 Primary transfer device 8 Developing device 9B Secondary transfer roller 10 Cleaning device 11 Fixing device 71 (+) Transfer bias blade 72 Exit side (-) bias blade 73 Entrance side (-) bias roller 74 Blade holders 76a, 76b Moving position 77 Metal plate 78 Non-woven fabric pasted 79, etc. Suspended roller

Claims (7)

An image carrier that is rotated with a toner image formed on the surface, a belt-like intermediate transfer member that rotates in the same direction while contacting the image carrier and transfers the toner image from the image carrier, and an intermediate transfer member On the other hand, a plurality of bias applying members that are opposite to the image carrier and apply the same polarity bias as the toner at the upstream position and the downstream position, and a bias having a polarity opposite to that of the toner in a region sandwiched between the plurality of bias applying members A transfer station comprising a bias applying member for providing
In an image forming apparatus having at least a part of a bias applying member that gives the same polarity as the toner and a cleaning member that removes dirt on the bias applying member that gives the opposite polarity to the toner,
The image forming apparatus removes dirt between the intermediate transfer member and the bias applying member by vibrating the bias applying member. The image forming apparatus according to claim 1.
In the image forming apparatus, the cleaning member vibrates until a predetermined job is finished and the intermediate transfer member is stopped. The image forming apparatus according to claim 1, wherein
The image forming apparatus is characterized in that vibration is performed by ultrasonic waves. An image carrier that is rotated with a toner image formed on the surface, a belt-like intermediate transfer member that rotates in the same direction while contacting the image carrier and transfers the toner image from the image carrier, and an intermediate transfer member On the other hand, a plurality of bias applying members that are opposite to the image carrier and apply the same polarity bias as the toner at the upstream position and the downstream position, and a bias having a polarity opposite to that of the toner in a region sandwiched between the plurality of bias applying members A transfer station comprising a bias applying member for providing
In an image forming apparatus having at least a part of a bias applying member that gives the same polarity as the toner and a cleaning member that removes dirt on the bias applying member that gives the opposite polarity to the toner,
In the image forming apparatus, the cleaning member removes dirt by passing through a contact portion between the intermediate transfer member and the bias applying member. The image forming apparatus according to claim 4.
In the image forming apparatus, the cleaning member performs a cleaning operation after a predetermined job is finished and the intermediate transfer member is stopped. An image carrier that is rotated with a toner image formed on the surface, a belt-like intermediate transfer member that rotates in the same direction while contacting the image carrier and transfers the toner image from the image carrier, and an intermediate transfer member On the other hand, a plurality of bias applying members that are opposite to the image carrier and apply the same polarity bias as the toner at the upstream position and the downstream position, and a bias having a polarity opposite to that of the toner in a region sandwiched between the plurality of bias applying members A transfer station comprising a bias applying member for providing
In an image forming apparatus having at least a part of a bias applying member that gives the same polarity as the toner and a cleaning member that removes dirt on the bias applying member that gives the opposite polarity to the toner,
The image forming apparatus is characterized in that the intermediate transfer member rotates in the reverse direction to that during normal image formation to remove stains at the contact portion between the intermediate transfer member and the bias applying member. The image forming apparatus according to claim 6.
In the image forming apparatus, the intermediate transfer member rotates in a reverse direction for a predetermined time after a predetermined job ends and the image forming unit stops.

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