JP2017090820A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of suppressing cleaning failure caused by pinching of paper powder between a cleaning member and an image carrier, and cleaning-member failure caused by excessive execution of a reverse rotation operation of the image carrier.SOLUTION: An image forming device 100 includes an image carrier 8 which carries a toner image and reversely rotates and a cleaning member 21 which comes into contact with the image carrier 8 and cleans the image carrier 8, and performs an image formation including a transfer of a toner image to a transfer material. The image forming device further includes control means 25 for making the image carrier 8 execute a reverse rotating operation at a non-image forming time in a direction reverse to the rotation direction of the image carrier 8 at the image forming time. The control means 25 performs a control in such a manner that an execution frequency of the reverse rotation operation with respect to the number of transfer materials S forming the image is lower in the case where a surface roughness of the transfer material S is a first roughness than in the case where the surface roughness of the transfer material S is a second roughness which is rougher than the first roughness.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, or a facsimile apparatus using an electrophotographic system or an electrostatic recording system.

  Conventionally, in an image forming apparatus using an electrophotographic system or an electrostatic recording system, a drum-shaped or belt-shaped photoconductor (electrophotographic photoconductor) or an image carrier (first image carrier) which is an electrostatic recording dielectric. A toner image is formed on the body by an appropriate image forming process. This toner image is directly transferred to a transfer material (direct transfer method), or temporarily transferred to an intermediate transfer member (second image carrier) and then secondarily transferred to a transfer material (intermediate transfer method). . In the direct transfer method, a toner image formed on an image carrier (first image carrier) that is a photosensitive member or an electrostatic recording dielectric is carried on a transfer material carrier (second image carrier). In some cases, the image is transferred to a transfer material that is conveyed. The transfer material carrier is an image carrier that carries and conveys a toner image via a transfer material. In general, many types of paper are used as transfer materials.

  After the toner image was transferred from the photosensitive member, electrostatic recording dielectric, and intermediate transfer member to the transfer member, the surface of the photosensitive member, electrostatic recording dielectric, and intermediate transfer member could not be transferred to the transfer member. Toner remains. Therefore, the remaining toner (transfer residual toner) is cleaned by a cleaning device. The transfer material carrier also has toner adhering to it when a jam (paper jam) occurs, or an adjustment toner image (patch) formed on it for image density adjustment or registration correction. Is cleaned by a cleaning device.

  Some cleaning devices use a cleaning blade that is a plate-like (blade-like) cleaning member made of an elastic member that comes into contact with an image carrier. A cleaning device using a cleaning blade is widely used because it has a relatively large effect of removing toner and can have a relatively compact structure mechanically. In a cleaning device using a cleaning blade, contact conditions such as a cleaning blade material, a contact angle of the cleaning blade to the image carrier, and a pressing load are set so that a sufficient cleaning effect can be obtained.

  However, even if the material and contact conditions are set as described above, the paper dust generated from the transfer material is sandwiched between the cleaning blade and the image carrier due to the characteristics of the toner and the external environment during cleaning. There is. When paper dust is sandwiched between the cleaning blade and the image carrier, the toner slips between the cleaning blade and the image carrier, resulting in a cleaning failure that prevents the image carrier from being sufficiently cleaned. Sometimes.

  Here, as a method of removing foreign matter between the cleaning blade and the image carrier such as the photosensitive member or intermediate transfer, there is a method of periodically rotating the rotatable image carrier (Patent Document 1).

JP 2010-243829 A

  By performing the reverse rotation operation of the image carrier as described above, it is possible to prevent paper dust from being sandwiched between the cleaning blade and the image carrier. Further, even when there is paper dust already sandwiched, it can be easily removed from the surface of the image carrier by the cleaning blade by releasing it from between the cleaning blade and the image carrier. Accordingly, it is possible to suppress poor cleaning due to the toner slipping between the cleaning blade and the image carrier due to the paper dust being sandwiched between the cleaning blade and the image carrier.

  However, if the frequency of performing the reverse rotation operation of the image carrier is too high, the cleaning blade may be easily turned over. Generally, the cleaning blade is brought into contact with the image carrier such that the counter direction with respect to the moving direction of the image carrier, that is, the free end of the cleaning blade faces the upstream side of the moving direction of the image carrier. At this time, the phenomenon that the free end of the cleaning blade is turned up so as to face the downstream side in the moving direction of the image carrier is “turning up” of the cleaning blade. When the cleaning blade is turned over, an appropriate cleaning effect cannot be obtained and the cleaning blade may be damaged. Even when the cleaning blade is not turned over, abnormal noise (also referred to as “blade squeal”) due to friction between the cleaning blade and the image carrier may easily occur.

  That is, a lubricant composed of toner and its external additive is present in a nip portion (herein also referred to as “blade nip portion”) formed by contact between the cleaning blade and the image carrier. The lubricant plays a role in properly maintaining the frictional force between the cleaning blade and the image carrier, and the cleaning blade can exhibit a good cleaning effect in a state where the frictional force is properly maintained. it can.

  However, if the frequency of performing the reverse rotation operation of the image carrier is increased too much, the lubricant in the blade nip portion is depleted, and the frictional force between the cleaning blade and the image carrier becomes too large. Turn over tends to occur. Similarly, blade squealing is also likely to occur. That is, the cleaning blade is liable to malfunction.

  Here, Patent Document 1 discloses increasing the frequency of executing the reverse rotation operation when the process speed is low and when the transfer material is thick. However, in Patent Document 1, since the relationship between the amount of paper dust of the transfer material and the cleaning failure due to the paper dust sandwiched is not considered, the lubricant in the blade nip portion is depleted by unnecessary reverse rotation operation, and the cleaning blade Problems such as turning over may occur.

  Therefore, an object of the present invention is to suppress the cleaning failure caused by the paper dust sandwiched between the cleaning member and the image carrier and the malfunction of the cleaning member caused by the excessive rotation of the image carrier. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

  The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention includes a rotatable image carrier that carries a toner image, and a cleaning member that contacts the image carrier and cleans the image carrier, and the toner image is transferred to a transfer material. In an image forming apparatus that performs image formation including transfer, a control unit that executes a reverse rotation operation of rotating the image carrier in a direction opposite to the rotation direction of the image carrier during image formation during non-image formation And the control means performs the reverse rotation operation with respect to the number of transfer materials on which image formation is performed. When the surface property of the transfer material is the first roughness, the surface property of the transfer material is higher. In the image forming apparatus, the control is performed so that the second roughness is less than the first roughness.

  According to the present invention, it is possible to suppress poor cleaning due to paper dust sandwiched between the cleaning member and the image carrier, and problems with the cleaning member due to excessive execution of the reverse rotation operation of the image carrier. .

1 is a schematic sectional view of an image forming apparatus. 2 is a block diagram illustrating a schematic control mode of the image forming apparatus. FIG. It is a flowchart figure of reverse rotation operation control. It is a schematic sectional drawing of the other example of an image forming apparatus. It is a schematic diagram of a surface property detection part. It is a block diagram which shows an example of the control aspect of a surface property detection part. It is the photograph and schematic diagram which show the detection result of a surface property detection part. It is a graph which shows the relationship between the detection result of a surface property detection part, and paper dust amount. It is a graph which shows the relationship between the detection result of a surface property detection part, and a weighting coefficient.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

[Example 1]
1. 1 is a schematic cross-sectional view of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 according to the present exemplary embodiment is a tandem type laser beam printer that employs an intermediate transfer method that can form a full-color image using an electrophotographic method.

  The image forming apparatus 100 includes first, second, third, and fourth image forming units PY, PM, PC, and PK as a plurality of image forming units (stations). Each of the image forming units PY, PM, PC, and PK forms yellow (Y), magenta (M), cyan (C), and black (K) toner images, respectively.

  In this embodiment, the configurations and operations of the image forming units PY, PM, PC, and PK are substantially the same except that the color of toner used in the development process described later is different. Therefore, hereinafter, unless there is a particular need for distinction, Y, M, C, and K at the end of a symbol representing an element for any color will be omitted, and the element will be described generally. In this embodiment, each image forming unit P includes a photosensitive drum 1, a charging roller 2, an exposure device 3, a developing device 4, a primary transfer roller 5, and a drum cleaning device 6 which will be described later.

  The image forming unit P includes a photosensitive drum 1 which is a rotatable drum type photosensitive member (electrophotographic photosensitive member) as a first image carrier. The photosensitive drum 1 is rotationally driven at a predetermined peripheral speed (process speed) in the direction of arrow R1 (clockwise) in the drawing. The surface of the rotating photosensitive drum 1 is uniformly charged to a predetermined potential having a predetermined polarity (negative polarity in this embodiment) by a charging roller 2 which is a roller-type charging member as a charging unit. At this time, a predetermined negative charging bias (charging voltage) is applied to the charging roller 2. The charged surface of the photosensitive drum 1 is scanned and exposed based on an image signal by an exposure device (laser unit) 3 as an exposure unit. As a result, an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 1. The electrostatic latent image formed on the photosensitive drum 1 is developed (visualized) using toner as a developer by a developing device 4 as developing means. As a result, a toner image is formed on the photosensitive drum 1. The developing device 4 includes a developing roller 41 as a developer carrying member that conveys toner to a portion (developing portion) facing the photosensitive drum 1, and a toner container 42 that stores the toner. The developing device 4 develops the electrostatic latent image by a reversal development method. That is, the toner charged to the same polarity as the charged polarity of the photosensitive drum 1 adheres to the exposed portion on the photosensitive drum 1 where the absolute value of the potential is lowered by being exposed after being uniformly charged. At this time, a predetermined negative developing bias (developing voltage) is applied to the developing roller 41. In this embodiment, the normal charging polarity of the toner, which is the charging polarity of the toner at the time of development, is negative.

  An intermediate transfer belt 8 that is an intermediate transfer member as a second image carrier is disposed facing the photosensitive drums 1Y, 1M, 1C, and 1K of the image forming units PY, PM, PC, and PK. The intermediate transfer belt 8 is composed of an endless belt having flexibility, and is stretched around a driving roller 9 and a driven roller 10 as a plurality of support members (stretching rollers). The intermediate transfer belt 8 rotates (circulates) in the direction of the arrow R2 (counterclockwise) in the figure at a predetermined peripheral speed (process speed) corresponding to the peripheral speed of the photosensitive drum 1 when the driving roller 9 is driven to rotate. Moving. On the inner peripheral surface side of the intermediate transfer belt 8, primary transfer rollers 5 that are roller-type primary transfer members serving as primary transfer means are disposed at positions corresponding to the photosensitive drums 1 Y, 1 M, 1 C, and 1 K. . The primary transfer roller 5 is pressed (biased) toward the corresponding photosensitive drum 1 via the intermediate transfer belt 8, and a primary transfer portion (primary transfer nip portion) N1 where the photosensitive drum 1 and the intermediate transfer belt 8 are in contact with each other. Form.

  The toner image formed on the photosensitive drum 1 as described above is transferred (primary transfer) to the intermediate transfer belt 8 by the action of the primary transfer roller 5 in the primary transfer portion N1. At this time, a primary transfer bias (primary transfer voltage) having a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) is applied to the primary transfer roller 5. For example, when forming a full-color image, yellow, magenta, cyan, and black toner images formed on the photosensitive drums 1Y, 1M, 1C, and 1K are sequentially superimposed on the intermediate transfer belt 8 and primarily transferred. .

  On the outer peripheral surface side of the intermediate transfer belt 8, a secondary transfer roller 11 that is a roller-type secondary transfer member as a secondary transfer unit is disposed at a position corresponding to the driving roller 9. The secondary transfer roller 11 is pressed (biased) toward the drive roller 9 via the intermediate transfer belt 8, and a secondary transfer portion (secondary transfer nip) where the intermediate transfer belt 8 and the secondary transfer roller 11 come into contact with each other. Part) N2. The toner image formed on the intermediate transfer belt 8 as described above is transferred in the form of a sheet such as paper conveyed between the intermediate transfer belt 8 and the secondary transfer roller 11 in the secondary transfer portion N2. It is transferred (secondary transfer) onto a material (recording material, recording medium, sheet) S. At this time, a secondary transfer bias (secondary transfer voltage) having a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) is applied to the secondary transfer roller 11. The transfer material S is stacked in the transfer material cassette 13 and is sent out from the transfer material cassette 13 by the feeding / conveying device 12. The feeding / conveying device 12 includes a feeding roller 14 that feeds the transfer material S and a pair of conveying rollers 15 that transports the fed transfer material S. The transfer material S conveyed by the feeding / conveying device 12 is introduced into the secondary transfer portion N2 by the registration roller pair 16 at a predetermined control timing.

  The transfer material S onto which the toner image has been transferred is introduced into a fixing device 17 as a fixing unit, and the toner image is fixed (fixed) thereon by being heated and pressurized in the fixing device 17. The transfer material S on which the toner image is fixed is discharged onto a discharge tray 19 by a discharge roller pair 18.

  On the other hand, the toner (primary transfer residual toner) remaining on the surface of the photosensitive drum 1 after the primary transfer step is removed from the surface of the photosensitive drum 1 and collected by the drum cleaning device 6 as a photosensitive member cleaning unit. The drum cleaning device 6 includes a drum cleaning blade 61 as a cleaning member and a drum waste toner container 62. The drum cleaning blade 61 scrapes the primary transfer residual toner from the surface of the rotating photosensitive drum 1 and stores it in the drum waste toner container 62.

  Further, the toner remaining on the surface of the intermediate transfer belt 8 after the secondary transfer step (secondary transfer residual toner) is removed from the surface of the intermediate transfer belt 8 and collected by a belt cleaning device 20 as an intermediate transfer member cleaning unit. The The belt cleaning device 20 includes a belt cleaning blade 21 as a cleaning member and a belt waste toner container 22. The belt cleaning blade 21 scrapes off the secondary transfer residual toner from the surface of the rotating intermediate transfer belt 8 and stores it in the belt waste toner container 22.

  In each image forming unit P, the photosensitive drum 1 and the charging roller 2, the developing device 4, and the drum cleaning device 6 as process means acting on the photosensitive drum 1 are integrated with the apparatus main body 110 of the image forming apparatus 100. A detachable process cartridge 7 is configured. The intermediate transfer belt 8, its stretching rollers 9 and 10, the primary transfer rollers 5, and the like constitute an intermediate transfer belt unit 80 that can be attached to and detached from the apparatus main body 110.

  In this embodiment, the peripheral speed (process speed) of the intermediate transfer belt 8 is 210 mm / sec (1/1 speed), 105 mm / sec (1/2 speed), and 70 mm according to an image forming mode described later. / Sec (1/3 speed) can be switched. In this embodiment, the peripheral speed of the photosensitive drum 1 is set to be substantially equal to the peripheral speed of the intermediate transfer belt 8, and when the peripheral speed of the intermediate transfer belt 8 is switched, the peripheral speed of the photosensitive drum 1 is set. The speed can be switched accordingly.

2. Belt Cleaning Device In this embodiment, the belt cleaning device 20 will be described with respect to the suppression of problems such as the above-described poor cleaning due to the sandwiching of paper dust and the turning of the cleaning blade due to excessive execution of the reverse rotation operation. Here, the configuration of the belt cleaning device 20 will be further described.

  The belt cleaning device (hereinafter simply referred to as “cleaning device”) 20 includes a belt cleaning blade (hereinafter also simply referred to as “blade”) 21. In this embodiment, a plate-like member made of urethane, which is an example of a rubber material as an elastic material, is used as the blade 21. Specifically, the width of the longitudinal direction arranged along the width direction of the intermediate transfer belt 8 (direction substantially orthogonal to the moving direction) is 232 mm, and the length of the short side direction (direction substantially orthogonal to the longitudinal direction) is. A plate-like member having a thickness of 12 mm and a thickness of 2 mm was used. The blade 21 is pressed against the intermediate transfer belt 8 with a predetermined pressure in a counter direction with respect to the moving direction of the intermediate transfer belt 8. That is, the blade 21 is in contact with the intermediate transfer belt 8 so that the free end side in the short direction faces the upstream side in the moving direction of the intermediate transfer belt 8 in the entire lengthwise direction. The blade 21 has a free end edge portion on the intermediate transfer belt 8 side and / or a surface in a predetermined range on the fixed end portion side from the edge portion in contact with the surface of the intermediate transfer belt 8. Here, the contact portion between the blade 21 and the intermediate transfer belt 8 is also referred to as a “blade nip portion CL”.

  In this embodiment, the blade 21 is pressed toward the driven roller 20 via the intermediate transfer belt 8 with a pressure of about 0.49 N / cm. The linear pressure of the blade 21 is preferably 0.4 N / cm or more and 0.8 N / cm or less in order to obtain a good cleaning property and not to damage the blade 21 and the intermediate transfer belt 8 due to an excessive pressing force. It is. Here, the linear pressure of the blade 21 is a pressure per unit length in the longitudinal direction of the blade 21, and the total pressure of the contact pressure of the blade 21 with respect to the intermediate transfer belt 8 is the longitudinal pressure of the blade nip portion CL. The value divided by the width. This linear pressure can be obtained by attaching a load converter to the intermediate transfer belt 8, pressing the blade 21 against the surface of the intermediate transfer belt 8, and measuring the load.

3. Control Mode FIG. 2 is a block diagram showing a schematic control mode of the image forming apparatus 100. In the present embodiment, the operation of each unit of the image forming apparatus 100 is comprehensively controlled by a control unit 25 as a control unit provided in the apparatus main body 110. The control unit 25 includes, as main components, a CPU 26 as arithmetic control means, a ROM 25B and RAM 25C as storage means, a cumulative weighted print number storage part 25D, and a communication I / F 25A as communication means. The communication I / F unit 25A may be an interface for connecting to a LAN such as a LAN card or a LAN board, for example, and receives print job data from an external device such as a personal computer. The CPU 26 reads a necessary program from the ROM 25 </ b> B and controls the operations of the respective units of the image forming apparatus 100 in a unified manner with timing. As a result, the control unit 25 causes the print operation based on the print job data received by the communication I / F unit 25A to be executed. In relation to the present embodiment, the control unit 25 causes a later-described reverse rotation operation to be executed at the time of non-image formation at a predetermined timing.

  Here, the image forming apparatus 100 executes a series of image output operations (print job, print operation) for forming and outputting an image on a single or a plurality of transfer materials S, which is started by one start instruction. A print job generally includes an image forming process, a pre-rotation process, a paper-to-paper process when images are formed on a plurality of transfer materials S, and a post-rotation process. The image forming process is a period in which electrostatic latent image formation, toner image formation, toner image primary transfer, and secondary transfer of the image that is actually formed and output on the transfer material S are performed. This is the period. More specifically, the timing at which the image is formed differs depending on the position where the electrostatic latent image formation, toner image formation, toner image primary transfer, and secondary transfer steps are performed. The pre-rotation process is a period for performing a preparatory operation before the image forming process from when the start instruction is input until the actual image formation is started. The inter-sheet process is a period corresponding to the interval between the transfer material S and the transfer material S when image formation is continuously performed on a plurality of transfer materials S (continuous image formation). The post-rotation process is a period during which an organizing operation (preparation operation) after the image forming process is performed. The non-image forming period is a period other than the image forming time, and is a preparatory operation at the time of turning on the power of the image forming apparatus 100 or returning from the sleep state. This is included during the previous multi-rotation process.

4). Reverse Rotation Operation In the image forming apparatus 100, various types of paper are generally used as the transfer material S in general. When the toner image on the intermediate transfer belt 8 is secondarily transferred to the transfer material S in the secondary transfer portion N2, a part of the paper powder generated from the paper used as the transfer material S is opposite to the toner. To the intermediate transfer belt 8 in some cases. The paper powder transferred to the intermediate transfer belt 8 is conveyed to the blade nip portion CL by the movement of the intermediate transfer belt 8 as in the case of the secondary transfer residual toner.

  Most of the paper powder transferred from the transfer material S to the intermediate transfer belt 8 in the secondary transfer portion N2 is removed from the surface of the intermediate transfer belt 8 by the blade 21 together with the secondary transfer residual toner. However, some paper dust may be sandwiched between the blade 21 and the intermediate transfer belt 8.

  Therefore, in the image forming apparatus 100 of the present embodiment, the intermediate transfer belt 8 is about 1 mm in the reverse rotation direction (moving direction) at the time of image formation in the post-rotation process as non-image formation at a predetermined timing. Executes a reverse rotation operation to rotate (move). Accordingly, the paper dust conveyed to the blade nip portion CL is suppressed from being sandwiched between the blade 21 and the intermediate transfer belt 8. Further, even when there is paper dust already sandwiched, it can be released from between the blade 21 and the intermediate transfer belt 8 and can be easily removed from the surface of the intermediate transfer belt 8 by the blade 21.

  The predetermined timing for executing the reverse rotation operation will be described in more detail later.

5. Surface property of transfer material and amount of paper dust As described above, by performing the reverse rotation operation, paper dust is sandwiched between the blade 21 and the intermediate transfer belt 8, so that the toner is transferred to the blade 21 and the intermediate transfer belt 8. Cleaning failure due to slipping through the gap can be suppressed. However, as described above, if the frequency of performing the reverse rotation operation is too high, problems such as turning over of the blade 21 and squealing of the blade (herein referred to as “turning up”) may easily occur. .

  According to the study by the present inventors, the degree of occurrence of poor cleaning due to paper dust being sandwiched between the blade 21 and the intermediate transfer belt 8 and the occurrence of turning of the blade 21 due to the reverse rotation operation are as follows. It was found that it was greatly affected by the surface properties of the paper and the amount of paper dust. Here, the amount of paper dust refers to the amount of paper dust transferred from the transfer material S to the intermediate transfer belt N2 by using a certain transfer material S for image formation (passing through the secondary transfer portion N2). However, a method for evaluating the amount will be described later.

  That is, the reverse rotation operation of the intermediate transfer belt 8 indicates that the paper dust is sandwiched between the blade 21 and the intermediate transfer belt 8 when the transfer material S having a relatively large amount of paper dust is used for image formation. There is an inhibitory effect. However, when the transfer material S having a relatively small amount of paper dust is used for image formation, the amount of paper powder falling off from the transfer material S is small in the first place. And the intermediate transfer belt 8 are relatively unlikely to be sandwiched. For this reason, when the transfer material S having a relatively small amount of paper dust is used for image formation, the necessity of executing the reverse rotation operation with high frequency is low. Further, as will be described in detail later, a high correlation is observed between the amount of paper dust and the surface property of the transfer material S, and a high correlation is also found between the surface property of the transfer material S and the amount of secondary transfer residual toner. is there. The transfer material S having a relatively rough surface has a larger amount of paper dust. On the other hand, the amount of secondary transfer residual toner is smaller as the transfer material S has a relatively smooth surface. Accordingly, when the transfer material S having a relatively smooth surface property is used for image formation, the amount of paper dust is small, so that the necessity for reverse rotation operation is low and the amount of secondary transfer residual toner is small. The supply amount of toner or external additive serving as a lubricant to the blade nip portion CL tends to be insufficient. Therefore, by performing an unnecessary reverse rotation operation, the lubricant in the blade nip portion CL is depleted, and the risk that the blade 21 is turned up increases.

In Comparative Example 1 in which the reverse rotation operation of the intermediate transfer belt 8 is performed at a constant timing, the degree of occurrence of cleaning failure due to the pinching of paper dust and the turning of the blade 21 was examined. The evaluation results are shown in Table 1. In the image forming apparatus 100 of Comparative Example 1, the frequency of performing the reverse rotation operation of the intermediate transfer belt 8 is set to once every 1000 printed sheets regardless of the type of the transfer material S used for image formation. Then, using the image forming apparatus 100 of Comparative Example 1, a total of 100,000 image output endurance tests were performed in which four continuous image formation print jobs were repeated. The image output in the endurance test was a mixed image composed of halftones and characters of each color of YMCK. In addition, the following No. 1-No. The same durability test was performed for each case using the transfer material S of No. 7. The characteristics of each transfer material S are as shown in Table 1.
(1) 3M CG3500
(2) HP Premium Presentation Paper 120g
(3) HP Brochure Paper 200g
(4) XEROX Business 4200
(5) Springhill Index DIGITAL
(6) 25% COTTON CONTENT
(7) NEENAH BOND SUB16

  The surface property of the transfer material S was measured with a Beck smoothness meter (Kumaya Riki Kogyo). Since the Beck smoothness is measured by the inflow speed (time) of the air flowing in from the gap between the rubber material and the transfer material S that are in close contact, a large value indicates that the surface property of the transfer material S is smooth, Conversely, a small value indicates that the surface property of the transfer material S is rough. Here, the surface property of the transfer material S having a Beck smoothness of less than 20 seconds is “rough”, the surface property of the transfer material S having a Beck smoothness of 40 seconds or more is “smooth”, and the Beck smoothness is 20 seconds or more and less than 40 seconds. The surface property of the transfer material S was “normal”.

  The amount of paper dust is determined by the weight percentage of Ca contained in the waste toner in the waste toner container 22 after outputting 10,000 images with a printing rate (image ratio) of 5% using the target transfer material S. did. The amount of paper powder of the transfer material S having a Ca weight percentage of 1.5% or more is “large”, and the amount of paper powder of the transfer material S less than 0.5% is “low”, and is 0.5% or more. The amount of paper powder of the transfer material S less than 1.5% was defined as “normal”.

  First, it can be seen that there is a high correlation between the surface properties of the transfer material S and the amount of paper dust. The transfer material S having a rough surface property has a large amount of paper powder, and the transfer material S having a smooth surface property has a small amount of paper powder.

  In addition, No. having a surface property of “normal” and a paper powder amount of “normal”. 4 and no. In the transfer material S of No. 5, neither the cleaning failure due to the sandwiching of the paper powder nor the turning of the blade 21 due to the excessive execution of the reverse rotation operation occurred. This indicates that the execution frequency of the reverse rotation operation of the intermediate transfer belt 8 in Comparative Example 1 (once every 1000 sheets) is an appropriate frequency with respect to the amount of paper dust of these transfer materials S. Yes. That is, when these transfer materials S are used for image formation, if the reverse rotation operation of the intermediate transfer belt 8 is executed at this frequency, the sandwiching of paper dust is suppressed and the lubricant in the blade nip portion CL is not depleted. Can be.

  On the other hand, No. 1 with a “rough” surface property and a “large” amount of paper dust. 6 and no. In the transfer material S of No. 7, the blade 21 was not turned up, but a cleaning failure occurred due to the paper powder being caught. This indicates that the frequency of reverse rotation operation of the intermediate transfer belt 8 in Comparative Example 1 is too low for these transfer materials S (once every 1000 sheets). That is, when these transfer materials S are used for image formation, if the reverse transfer operation of the intermediate transfer belt 8 is executed at this frequency, paper dust is sufficiently suppressed from being sandwiched between the blade 21 and the intermediate transfer belt 8. Can not do.

  On the contrary, the surface property is “smooth” and the amount of paper dust is “small”. 1-No. In the transfer material S of No. 3, the blade 21 was turned up, although no cleaning failure occurred due to the sandwiching of the paper powder. This indicates that the frequency of reverse transfer operation of the intermediate transfer belt 8 in Comparative Example 1 is too high for these transfer materials S (once every 1000 sheets). That is, when these transfer materials S are used for image formation, if the reverse rotation operation of the intermediate transfer belt 8 is executed at this frequency, the lubricant in the blade nip portion CL is depleted and the blade 21 is likely to be turned up. More specifically, since these transfer materials S having a small amount of paper powder have a smooth surface property, when these transfer materials S are used for image formation, the transfer materials S having a rough surface property are used two times. The amount of the next transfer residual toner is small. Therefore, when these transfer materials S are used for image formation, the amount of secondary transfer residual toner supplied to the blade nip portion CL and acting as a lubricant is small. Therefore, when these transfer materials S are used for image formation, the blade 21 is likely to be turned over when a high-frequency reverse rotation operation is performed.

6). Control Method of Reverse Rotation Operation in the Present Example Based on the above test results, in this example, the reverse rotation operation of the intermediate transfer belt 8 is executed according to the information about the surface property of the transfer material S used for image formation. Determine how often. In particular, in this embodiment, the surface property of the transfer material S is determined from the image forming mode selected when the print job is executed. That is, in this embodiment, information on the image forming mode correlated with the surface property of the transfer material S used for image formation is used as the information on the surface property of the transfer material S.

  In this embodiment, the image forming apparatus 100 can execute a print job in each of the image forming modes of “OHT”, “Gloss”, “Normal”, “Heavy”, “Rough”, and “Light Rough”. Yes. “OHT” and “Gloss” are image forming modes in which process conditions such as process speed are set so as to be suitable for OHT (transparent sheet for overhead projector) and high gloss paper, and the surface of these transfer materials S The nature generally corresponds to the “smoothness” described above. “Normal” and “Heavy” are image forming modes in which process conditions are set so as to be suitable for plain paper and thick paper, respectively. The surface properties of these transfer materials S are generally the above-mentioned “normal”. Corresponding to Further, “Rough” and “Light Rough” are image forming modes in which process conditions are set so as to be suitable for rough paper, and the surface property of the transfer material S generally corresponds to the above-mentioned “rough”. . Examples of the transfer material S assumed to be suitable for selecting each image forming mode are as shown in Table 1.

  Therefore, for example, when “OHT” or “Gloss” is selected as the image forming mode when the print job is executed, the surface property of the transfer material S can be determined to be “smooth”. Similarly, for example, when “Rough” or “Light Rough” is selected, the surface property of the transfer material S can be determined to be “rough”, and when “Normal” or “Heavy” is selected, the transfer is performed. It can be determined that the surface property of the material S is “normal”.

  In this embodiment, the control unit 25 determines the surface property of the transfer material S based on information designating the image forming mode included in the print job data. The image forming mode is input (or selected) by an operator from, for example, a printer driver installed in an external device or an operation unit (operation panel) provided in the apparatus main body 110.

  In this embodiment, when the control unit 25 determines that the surface property of the transfer material S is “smooth”, the amount of paper dust is small, and therefore the frequency of executing the reverse rotation operation of the intermediate transfer belt 8 is relatively set. Lower. Conversely, when the control unit 25 determines that the surface property of the transfer material S is “rough”, the control unit 25 increases the frequency of executing the reverse rotation operation of the intermediate transfer belt 8.

  In this embodiment, as an example of a method for controlling the frequency of executing the reverse rotation operation of the intermediate transfer belt 8, a method of accumulating the number of prints is used. FIG. 3 is a flowchart illustrating a procedure of reverse rotation operation control of the intermediate transfer belt 8 executed by the control unit 25 in the present embodiment. In this reverse rotation operation control, the timing for executing the reverse rotation operation of the intermediate transfer belt 8 is determined and executed.

  When receiving the print job (step 1), the control unit 25 acquires the number n of prints of the received print job (step 2), and acquires the cumulative weighted print number A (step 3). The print number n is included in the data of the accepted print job, and the cumulative weighted print number A is stored in the cumulative print number storage unit 25D. Here, the cumulative weighted print number A is a value obtained by integrating the weighted print number obtained by multiplying the print number by a predetermined coefficient set in advance corresponding to information on the surface property of the transfer material S. In this embodiment, the information on the surface property of the transfer material S is information on the image forming mode, and the predetermined coefficient is determined in advance in consideration of the influence on the occurrence of defective cleaning due to the sandwiching of paper dust. In other words, the cumulative weighted print number A indicates the frequency of occurrence of cleaning failure due to the estimated paper dust sandwiched in the number of prints.

  Next, the control unit 25 determines the surface property of the transfer material S from the image forming mode of the received print job (step 4). In this embodiment, the control unit 25 determines the surface property of the transfer material S in three stages of “smooth”, “normal”, and “rough” according to the method for determining the surface property of the transfer material S described above.

  When determining that the surface property of the transfer material S is “normal”, the control unit 25 adds 1n obtained by multiplying the number n of prints by the weighting coefficient 1 to A (step 6). In addition, when the control unit 25 determines that the surface property of the transfer material S is “smooth”, the frequency of executing the reverse rotation operation of the intermediate transfer belt 8 is set lower than when it is determined “normal”. Control. The transfer material S having a “smooth” surface property has a small amount of paper dust and has a low risk of occurrence of cleaning failure due to pinching of the paper dust, while the blade 21 is turned over when the reverse rotation operation is frequently performed. This is because the risk is high. Specifically, the control unit 25 adds 0.5n obtained by multiplying the number n of printed sheets by a weighting coefficient 0.5 to A (step 5). Conversely, when the control unit 25 determines that the surface property of the transfer material S is “rough”, the control unit 25 performs the reverse rotation operation of the intermediate transfer belt 8 more frequently than when it is determined “normal”. To control. The transfer material S having a “rough” surface property has a high risk of causing a cleaning failure due to a large amount of paper dust. On the other hand, even if the reverse rotation operation is frequently performed, the blade 21 is turned up. This is because the risk does not increase. Specifically, the control unit 25 adds 2n obtained by multiplying the number of prints n by the weighting factor 2 to A (step 7).

  Next, the control unit 25 determines whether or not the cumulative weighted print number A exceeds 1000 (step 8). When it is determined that the cumulative weighted print number A exceeds 1000, the control unit 25 executes the reverse rotation operation of the intermediate transfer belt 8 described above during the post-rotation process of the print job (step 9). Thereafter, the control unit 25 resets the cumulative weighted print number A to 0 (step 10), stores the reset cumulative weighted print number A in the cumulative weighted print number storage unit 25D (step 11), and ends the series of operations. To do. If the control unit 25 determines in step 8 that the cumulative weighted print number A does not exceed 1000, the control unit 25 updates and stores the cumulative weighted print number A without executing the reverse rotation operation (step 11). ), And a series of operations are terminated. The above control is performed in parallel with the execution of the main control such as the pre-rotation process and the image forming process when the print job is started.

  Table 2 shows the evaluation results of this example in which the reverse rotation operation of the intermediate transfer belt 8 was executed by the reverse rotation operation control described above. The evaluation method is the same as in the case of obtaining the evaluation results in Table 1.

  In this embodiment, in the case of the transfer material S having a “smooth” surface property, the weighting coefficient is set to 0.5. Therefore, the reverse rotation operation of the intermediate transfer belt 8 is performed once every 2000 sheets. Compared with the case of Comparative Example 1, it becomes lower. As a result, no. 1-No. In the transfer material S of 3, the blade 21 was not turned up. Further, in this embodiment, in the case of the transfer material S having a “rough” surface property, the weighting coefficient is set to 2, so the frequency of executing the reverse rotation operation of the intermediate transfer belt 8 is once every 500 sheets. It becomes higher than the case of Example 1. As a result, no. 6 and no. In the transfer material S of No. 7, no cleaning failure occurred due to the sandwiching of paper dust.

  In the present embodiment, the surface property of the transfer material S is determined from the image forming mode, but the present invention is not limited to this. For example, the operator may input (or select) the type of the transfer material S from a printer driver installed in an external device or from an operation unit (operation panel) provided in the apparatus main body 110. . Examples of the type of transfer material S input (or selected) at this time are as described in Tables 1 and 2, for example. That is, if the operator inputs (or selects) an item related to the surface property of the transfer material S and controls the frequency of executing the reverse rotation operation of the intermediate transfer belt 8 accordingly, the same as above. An effect can be obtained.

  Further, the surface property of the transfer material S is not limited to three types of “smooth”, “normal”, and “rough”, and may be classified more finely (in more stages). Conversely, it may be classified into fewer stages.

  Thus, in this embodiment, the image forming apparatus 100 includes a rotatable image carrier (intermediate transfer belt) 8 that carries a toner image, and a cleaning that contacts the image carrier 8 and cleans the image carrier 8. And a member (cleaning blade) 21. The image forming apparatus 100 performs image formation including transferring a toner image to the transfer material S. Further, the image forming apparatus 100 includes a control unit (control unit) 25 that executes a reverse rotation operation for rotating the image carrier 8 in a direction opposite to the rotation direction of the image carrier 8 at the time of image formation during non-image formation. Have. And the control means 25 controls the timing which performs reverse rotation operation | movement based on the information regarding the surface property of the transfer material S used for image formation. That is, the control unit 25 performs the reverse rotation operation with respect to the number of transfer materials S on which image formation is performed when the surface property of the transfer material S is the first roughness. Is controlled to be less than in the case of the second roughness that is coarser than the first roughness. In other words, the frequency of executing the reverse rotation operation when the control unit 25 continuously forms an image on the transfer material S having the first roughness is rougher than the first roughness. Control is performed so as to be less than the frequency when images are continuously formed on the transfer material S having the second roughness. In particular, in the present embodiment, the control unit 25 multiplies the number of transfer materials S used for image formation by a predetermined coefficient set in advance corresponding to the surface property of the transfer material S and accumulates them. In response, a reverse rotation operation is executed. In this embodiment, the image forming apparatus 100 can perform image formation with a plurality of operation settings (process conditions and image formation modes) associated with the surface property of the transfer material S used for image formation. . Then, the control means 25 determines the surface property of the transfer material S used for image formation from the operation settings designated for image formation. The control means 25 may determine the surface property of the transfer material S used for image formation from the type of the transfer material S designated as used for image formation.

  As described above, in this embodiment, the surface property of the transfer material S is determined from the image forming mode, and the frequency of performing the reverse rotation operation of the intermediate transfer belt 8 is controlled based on the determination result. Thereby, even when the transfer material S having a relatively large amount of paper dust is used for image formation, it is possible to suppress the cleaning failure due to the sandwiching of the paper dust, and the transfer material S having a relatively small amount of paper dust is used for image formation. The occurrence of turning of the blade 21 can be suppressed.

[Example 2]
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Accordingly, in the image forming apparatus of this embodiment, elements having the same or corresponding functions and configurations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

1. In this embodiment, the surface property of the transfer material S is determined from the detection result of the detecting means for detecting the surface property of the transfer material S. Thus, even when the operator inputs (or selects) information on the image forming mode or the type of the transfer material S by mistake, the surface property of the transfer material S is more accurately determined on the image forming apparatus 100 side, The reverse rotation operation of the intermediate transfer belt 8 can be executed at a frequent frequency.

  FIG. 4 is a schematic cross-sectional view of the image forming apparatus 100 of the present embodiment. In this embodiment, the image forming apparatus 100 serves as a detection unit that detects the surface property of the transfer material S on the downstream side of the registration roller 16 and the upstream side of the secondary transfer portion N2 in the conveyance direction of the transfer material S. It has a surface property detector 50.

  FIG. 5 is a schematic diagram of the surface property detector 50 in the present embodiment. The surface property detection unit 50 includes an LED 51 as an irradiation unit that irradiates the surface of the transfer material S with light. Further, the surface property detector 50 includes an imaging lens 52 as an imaging unit that receives reflected light reflected from the surface of the transfer material S by the light emitted from the LED 51 and forms an image. In addition, the surface property detection unit 50 includes a CMOS line sensor 53 as an imaging unit that images the light imaged by the imaging lens 52. The position where the light irradiated from the LED 51 in the transfer direction of the transfer material S is reflected by the transfer material S is the reflection portion. The reflected light reflected by the reflecting portion is captured as a surface image of the transfer material S by the CMOS line sensor 53. Further, the surface property detector 50 includes a protective member 54 that protects the imaging lens 52 and the LED 51. Further, the surface property detection unit 50 includes a pressing member 55 that is disposed to face the protection member 54 and presses the transfer material S conveyed between the protection member 54 against the protection member 54. In this embodiment, a white LED is used as the LED 51. The LED 51 is not limited to the white LED as long as the transfer material S can be irradiated. In this embodiment, the light irradiated from the LED 51 to the transfer material S is irradiated at an angle of 10 degrees with respect to the surface of the transfer material S. Note that this angle is an example, and the angle is not limited to 10 degrees as long as an image sufficient for determining the transfer material S can be obtained. In the present embodiment, the CMOS line sensor 53 is used as the imaging means, but the present invention is not limited to this, and a two-dimensional area sensor or the like can be used.

  FIG. 6 is a block diagram illustrating an example of a control mode of the surface property detection unit 50. Light is irradiated from the LED 51 onto the surface of the transfer material S being conveyed through the reflection portion. The reflected light from the transfer material S is imaged by the imaging lens 52 and a surface image is captured by the CMOS line sensor 53. The surface image of the transfer material S imaged by the CMOS line sensor 53 is output to the surface property determination processing unit 70 as a determination means. The surface property discrimination processing unit 70 performs AD conversion on the received surface image of the transfer material S in the AD conversion unit 71, and obtains an image on the same straight line that is substantially orthogonal to the transfer direction of the transfer material S. In this embodiment, an 8-bit A / D conversion IC is used for the A / D conversion unit 71, and the A / D conversion unit 71 outputs a value from 0 to 255. Next, in the image extraction unit 72 and the storage area 75, the surface image of the transfer material S received from the A / D conversion unit 71 is joined in the transport direction of the transfer material S to obtain a two-dimensional surface image. In this embodiment, the transfer speed of the transfer material S at the time of detection by the surface property detection unit 50 is 210 mm / sec, and the resolution of the CMOS line sensor 53 is 600 dpi for one line (about 42 μm per dot). The image size is 236 dots × 118 dots as an example, and in this case, an area corresponding to 10 mm × 5 mm of the transfer material S can be imaged. Imaging by the CMOS line sensor 53 is performed at 42 μm / (210 mm / sec) and at intervals of about 200 μsec or more. Thereby, it is possible to take an image so that the imaging areas on the transfer material S do not overlap.

  Further, in the image extraction unit 72, based on information such as the optical axis and the effective image range stored in the storage area 75 from the obtained two-dimensional surface image, the surface image used for discrimination of the type of the transfer material S is determined. Extraction is performed. At this time, in order to determine the surface property of the transfer material S, the surface image is subjected to shading correction (processing for removing unevenness from an image having uneven density). The feature amount calculation unit 73 calculates feature amounts from the extracted surface image. An example of the feature amount calculation method will be described later. Then, the surface property determination unit 74 determines the surface property of the transfer material S based on the result calculated by the feature amount calculation unit 73. As an example, the result of the determination of the surface property of the transfer material S can be in three stages, “rough”, “normal”, and “smooth”, as in the first embodiment. That is, the range of the feature amount described later is divided into three ranges corresponding to “rough”, “normal”, and “smooth” in the first embodiment, and the calculated feature amount corresponds to any range. The surface property of the transfer material S can be discriminated in three stages as in the first embodiment. In this case, the determination result is reflected in step 4 of the flowchart of FIG. 3 described in the first embodiment. Accordingly, in this case as well, it is possible to control the frequency of executing the reverse rotation operation of the intermediate transfer belt 7 in the same manner as in the first embodiment. In this case, the results shown in Table 2 can be obtained as in Example 1.

2. Next, another example of the method for determining the surface property of the transfer material S will be described.

  FIG. 7 shows a part of the surface image of the transfer material S obtained by the above-described method. With the transfer material S having a relatively rough surface property, a surface image as shown in FIG. 7A can be obtained. When data of an arbitrary line of this surface image is extracted, a surface profile curve as shown in FIG. 7C is obtained. On the other hand, with the transfer material S having a relatively smooth surface property, a surface image as shown in FIG. 7B can be obtained. When data of an arbitrary line of the surface image is extracted, a surface profile curve as shown in FIG. 7D is obtained.

  Therefore, as an example of the above-described feature amount, by calculating the Rz (maximum unevenness difference) of the obtained surface profile curve, the difference integrated value with the adjacent dots (length of the surface profile curve), etc., the transfer material S It is possible to quantify the surface characteristics.

As an example, the following No. 1-No. The surface characteristics of the three types of transfer material S of No. 3 were quantified as follows. From the surface image obtained from the surface property detection unit 50, a difference integrated value for integrating the difference from one line of adjacent dots is calculated for all lines. And the average value of the difference integrated value regarding each calculated line is calculated, and it is set as an average difference integrated value. FIG. 8 shows the relationship between the calculated average difference integrated value and the amount of paper dust. The amount of paper dust was measured by the same method as described in Example 1.
(1) GF600
(2) GF-C081
(3) Xerox Business 4200

  It can be seen from FIG. 8 that there is a high correlation between the average difference integrated value obtained by the surface property detector 50 and the amount of paper dust. In other words, when the average difference integrated value is the first value and the second value larger than the first value, the second value is greater than the first value. The surface property of the transfer material S is rough. Then, the amount of paper dust of the transfer material S is larger in the case of the second value than in the case of the first value. From this, it is possible to set an optimum weighting factor according to the amount of paper dust of the transfer material S based on the average difference integrated value for an arbitrary transfer material S.

  FIG. 9 shows an example of the relationship between the average difference integrated value and the weighting coefficient. The weighting coefficient shown in FIG. 9 is optimally adjusted in accordance with the amount of paper dust of each transfer material S from the viewpoint of suppressing cleaning failure due to paper dust pinching and turning of the blade 21 due to excessive execution of reverse rotation operation. Value.

  As described above, it is possible to calculate the weighting coefficient value steplessly in accordance with the average difference integrated value corresponding to the surface property of the transfer material S. As a result, the execution timing of the reverse rotation operation can be controlled more finely than in the case where the surface property of the transfer material S is judged stepwise such as “rough”, “normal”, and “smooth” as described above.

  In Table 3, in place of the processing of Step 4 to Step 7 of FIG. 3, reverse rotation operation control for performing processing for calculating the cumulative weighted print number A using the optimum weighting coefficient obtained from the average difference integrated value described above was executed. The evaluation result about each said transfer material S in the case is shown. The evaluation method is the same as in the case of obtaining the evaluation results in Table 1.

  As shown in Table 3, in any of the transfer materials S, it was possible to suppress the cleaning failure due to the sandwiching of the paper dust and the occurrence of turning of the blade 21 due to the excessive execution of the reverse rotation operation. The determination method of the surface property of the transfer material S is more preferable than the above-described three-step (or finite-step) surface property determination method in that the weighting factor can be set continuously in a stepless manner. It can be said that.

  As described above, in the present exemplary embodiment, the image forming apparatus 100 includes the detecting unit (surface property detecting unit) 50 that detects the surface property of the transfer material S used for image formation. The control unit (control unit) 25 determines the surface property of the transfer material S used for image formation from the detection result of the detection unit 50.

  As described above, in this embodiment, the surface property of the transfer material S is determined from the detection result of the surface property detection unit 50, and the frequency of performing the reverse rotation operation of the intermediate transfer belt 8 is controlled based on the determination result. . Thereby, for example, even when an image forming mode that does not correspond to the surface property of the transfer material S is selected by mistake, the reverse rotation operation of the intermediate transfer belt 8 is executed at an appropriate frequency according to the surface property of the transfer material S. can do.

[Others]
As mentioned above, although this invention was demonstrated according to the specific Example, this invention is not limited to the above-mentioned Example.

  In the above-described embodiment, the frequency of executing the reverse rotation operation is controlled based on the cumulative weighted print number, but the present invention is not limited to this. For example, the number of prints may be integrated for each piece of information (image formation mode, type of transfer material, etc.) relating to the surface properties of the transfer material used for image formation. In this case, for example, the reverse rotation operation can be executed when any of the integrated values exceeds a preset threshold value corresponding to information on the surface property of the transfer material.

  In the above-described embodiment, the reverse rotation operation is performed during the post-rotation process. However, the reverse rotation operation can be performed at any timing as long as it is during non-image formation. For example, when it is determined that it is time to execute the reverse rotation operation in the same manner as in the above-described embodiment, it can be executed at the time of the inter-sheet process or the pre-rotation process of the subsequent job.

  Further, in the above-described embodiment, the description has been given on the suppression of the malfunction such as the cleaning failure due to the paper dust sandwiched in the belt cleaning device and the blade turning due to the excessive execution of the reverse rotation operation. However, in the case of an intermediate transfer type image forming apparatus, the paper dust may be transferred to the photosensitive drum as the first image carrier via the intermediate transfer belt as the second image carrier. Powder may be caught between the drum cleaning device blade and the photosensitive drum. Therefore, it is possible to prevent paper dust from being sandwiched between the blade and the photosensitive drum by performing the reverse rotation operation of the photosensitive drum. However, if the frequency of reverse rotation of the photosensitive drum is too high, problems such as turning up of the blade may occur. Therefore, by controlling the frequency of the reverse rotation operation of the photosensitive drum by the reverse rotation operation control similar to the above-described embodiment, the cleaning failure due to the pinching of paper dust and the turning of the blade due to excessive execution of the reverse rotation operation are controlled. And other problems can be suppressed. According to the above-described embodiment, when the reverse transfer operation of the intermediate transfer belt is executed, the reverse rotation operation of the photosensitive drum can be executed simultaneously. Alternatively, the reverse rotation operation of the intermediate transfer belt and the reverse rotation operation of the photosensitive drum can be executed at different timings. When the reverse transfer operation of the intermediate transfer belt is performed alone, the intermediate transfer belt can be separated from the photosensitive drum.

  Further, the reverse rotation operation control according to the present invention is particularly effective in the configuration in which the transfer material and the image carrier are in contact with each other. Therefore, even when the image carrier is a transfer material carrier that carries and conveys the transfer material, the same as above. The effect of can be obtained. That is, instead of the intermediate transfer belt in the above-described embodiment, a direct transfer type image forming apparatus having a transfer material carrying belt (conveyance belt) as a transfer residual carrier that carries and conveys a transfer material is well known. In this image forming apparatus, a toner image is directly transferred from a photosensitive drum to a transfer material carried on a transfer material carrying belt. Also in such an image forming apparatus, there is a cleaning device provided with a blade for removing from the transfer material carrying belt the toner adhering to the occurrence of a jam or the patch formed for image density adjustment or registration correction. May be provided. Then, the paper powder transferred from the transfer material to the transfer material carrying belt may be sandwiched between the blade and the transfer material carrying belt. Therefore, it is possible to prevent paper dust from being sandwiched between the blade and the transfer material carrying belt by executing the reverse rotation operation of the transfer material carrying belt. However, when the reverse rotation operation of the transfer material carrying belt is performed too frequently, problems such as turning up of the blade may occur. Therefore, by controlling the frequency of performing the reverse rotation operation of the transfer material carrying belt by the reverse rotation operation control similar to the above-described embodiment, the blade due to the cleaning failure due to the pinching of paper dust and the excessive execution of the reverse rotation operation Troubles such as turning over can be suppressed. In such an image forming apparatus, as in the case of the intermediate transfer type image forming apparatus, the reverse rotation operation of the photosensitive drum can be performed simultaneously with the reverse rotation operation of the transfer material carrying belt or at another timing. it can. When the reverse rotation operation of the transfer material carrying belt is performed alone, the transfer material carrying belt can be separated from the photosensitive drum.

  In other words, the reverse rotation operation control according to the present invention includes a rotatable conveyance member that contacts the sheet, and a cleaning member that contacts the conveyance member and cleans the conveyance member, and conveys the sheet by the conveyance member. It works favorably in the transport device. Examples of the conveying member include an intermediate transfer belt and a transfer material carrying belt in the image forming apparatus. However, the conveying member is not limited thereto, and may be a conveying member that conveys a sheet such as paper in an arbitrary apparatus. For example, an endless belt that sandwiches and conveys a sheet with another member, an endless belt that conveys and conveys a sheet, and the like can be given. The conveying apparatus includes a control unit that executes a reverse rotation operation for rotating the conveying member in a direction opposite to the rotation direction of the conveying member during conveyance of the sheet when the sheet is not conveyed. Then, the control means may control the timing for executing the reverse rotation operation based on the information on the surface property of the conveyed sheet. In other words, the frequency at which the control unit performs the reverse rotation operation with respect to the number of sheets to be conveyed is such that the surface property of the sheet is rougher than the first roughness when the surface property of the sheet is the first roughness. The control is performed so as to be less than the case of the second roughness. In other words, the frequency of the reverse rotation operation when the control unit continuously conveys the sheet having the first roughness is the second roughness that is rougher than the first roughness. The control is performed so that the frequency is less than that in the case where the sheet is continuously conveyed.

  Further, the image forming apparatus is not limited to a color image forming apparatus, and may be a monochrome image forming apparatus. That is, for example, in an image forming apparatus that directly transfers a toner image from a photosensitive drum to a transfer material that is nipped and conveyed between a photosensitive drum as an image carrier and a transfer member such as a transfer roller, the photosensitive drum cleaning device In this regard, the present invention may be applied. Further, the image carrier may be an electrostatic recording dielectric.

  In addition, the photosensitive member is not limited to a drum type, and may be, for example, an endless belt. Further, the intermediate transfer member and the transfer material carrier are not limited to those composed of endless belts, but are, for example, drum-type members constructed by stretching a film (sheet) on a frame. There may be.

  The present invention works particularly well when the cleaning member is a cleaning blade, but the cleaning member is not limited to a blade-like one. For example, for a cleaning member that is concerned about the occurrence of defective cleaning due to pinching of paper dust, such as a block-shaped (pad-shaped) one, and malfunction (such as the occurrence of abnormal noise) due to excessive execution of reverse rotation operation, this By applying the invention, the same effect as described above can be expected.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 8 Intermediate transfer belt 21 Cleaning blade 25 Control part 100 Image forming apparatus

Claims (9)

An image forming method comprising: a rotatable image carrier that carries a toner image; and a cleaning member that contacts the image carrier and cleans the image carrier, and includes transferring the toner image to a transfer material. In the image forming apparatus to perform,
Control means for executing a reverse rotation operation for rotating the image carrier in a direction opposite to the rotation direction of the image carrier during image formation during non-image formation;
When the frequency of executing the reverse rotation operation with respect to the number of transfer materials on which image formation is performed is such that the surface property of the transfer material is the first roughness, the surface property of the transfer material is the first property. An image forming apparatus, wherein the control is performed so that the second roughness is less than that of the second roughness.   The control means executes the reverse rotation operation according to a value accumulated by multiplying the number of transfer materials used for image formation by a predetermined coefficient set in advance corresponding to the surface property of the transfer material. The image forming apparatus according to claim 1, wherein:   The image forming apparatus can perform image formation with a plurality of operation settings associated with the surface property of a transfer material used for image formation, and the control unit can control the surface property of the transfer material used for image formation. The image forming apparatus according to claim 1, wherein the image forming apparatus is determined from the operation setting designated for image formation.   The image forming apparatus according to claim 1, wherein the control unit determines the surface property of the transfer material used for image formation from the type of the transfer material designated as used for image formation. .   The image forming apparatus includes a detection unit that detects a surface property of a transfer material used for image formation, and the control unit determines the surface property of the transfer material used for image formation from a detection result of the detection unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The image forming apparatus according to claim 1, wherein the cleaning member is a cleaning blade.   The image forming apparatus according to claim 1, wherein the image carrier is a photoconductor, an intermediate transfer member, or a transfer material carrier. In a conveying apparatus that has a rotatable conveying member that contacts a sheet, and a cleaning member that contacts the conveying member and cleans the conveying member, and conveys the sheet by the conveying member,
Control means for executing a reverse rotation operation for rotating the conveying member in a direction opposite to the rotation direction of the conveying member during conveyance of the sheet when the sheet is not conveyed;
In the case where the frequency of executing the reverse rotation operation with respect to the number of conveyed sheets is the first roughness of the sheet, the control means has a surface roughness of the sheet that is higher than that of the first roughness. A conveying device that performs control so as to be less than in the case of a rough second roughness.   The transport apparatus according to claim 8, wherein the transport member is an endless belt.