JP5741800B2 - Image forming apparatus, image forming apparatus control method, and image forming apparatus control program - Google Patents

Description

  The present invention relates to an image forming apparatus, an image forming apparatus control method, and an image forming apparatus control program.

  In an image forming apparatus using an intermediate transfer belt method in an electrophotographic process, a phenomenon called “meklet” may occur in which the blade edge of the cleaning blade that is in contact with the intermediate transfer belt is swollen in the rotational drive direction of the intermediate transfer belt. is there. Further, due to the peeling, “slip-through” may occur in which the residual toner on the surface of the intermediate transfer belt is not removed and the cleaning blade passes through.

  Meklet and slipping cause poor cleaning of the intermediate transfer belt. Due to this poor cleaning, a phenomenon called “hollow-out” occurs in which a part of the image formed by the image forming apparatus appears white.

  One cause of the occurrence of slipping and slip-through is a change in contact angle on the intermediate transfer belt due to the lubricant transferred from the photosensitive drum and the secondary transfer belt to the surface of the intermediate transfer belt.

  If the amount of transfer of lubricant to the intermediate transfer belt increases and the lubricant accumulates on the surface of the intermediate transfer belt, the contact angle of pure water with respect to the surface of the intermediate transfer belt increases, and creaking is likely to occur. It is known. Further, it is known that when the contact angle becomes small after being sufficiently large, slip-through is likely to occur. The “contact angle” is a measurable physical quantity indicating the wettability, and is used when calculating the surface energy.

  In order to prevent melee and slip-through, it is necessary to suppress the amount of change in the contact angle as much as possible. For this purpose, the lubricant transferred to the intermediate transfer belt may be removed, or the amount of lubricant applied to the photosensitive drum and the secondary transfer belt may be adjusted.

  In Patent Document 1, when the contact angle of the surface of the intermediate transfer member is increased, toner is discharged onto the intermediate transfer from the cleaning means of the intermediate transfer member, and the discharged toner is scraped off. A technique for reducing the contact angle of the surface is disclosed.

  In Patent Document 2, the surface friction coefficients of the photosensitive member and the intermediate transfer belt are detected by using both driving load information, and the surface friction coefficient of the intermediate transfer belt is larger than that of the photosensitive member and the intermediate transfer belt. A technique for controlling a lubricant application unit capable of moving toward and away from a transfer belt is disclosed.

JP 2006-30358 A JP 2009-103839 A

  However, according to Patent Document 1, in order to remove excess lubricant on the intermediate transfer member triggered by a change in the drive torque of the intermediate transfer member, when a change in the drive torque of the intermediate transfer member is detected, contact is made. The corner has already changed greatly.

  According to Patent Document 2, a change in the drive load level is detected in order to adjust the amount of lubricant applied to the surface of the photosensitive drum, triggered by a change in the drive load level of the intermediate transfer member drive motor. Sometimes, excessive lubricant has already been applied to the surface of the photosensitive drum, and the contact angle has already changed greatly.

  Therefore, it is difficult for any of the techniques to prevent melee, slip-through and poor cleaning of the intermediate transfer belt.

  An object of the present invention is to provide an image forming apparatus, a method for controlling the image forming apparatus, and an image forming apparatus capable of forming a high-quality image by preventing meklet, slip-through and poor cleaning of the intermediate transfer belt. It is to provide a control program.

The image forming apparatus according to the present invention includes a rotatable transfer member on which a toner image and a lubricant are carried, and the lubricant that is in contact with the surface of the transfer member and transferred onto the surface of the transfer member. A removal roller for removing the agent; a drive unit for driving the removal roller to rotate; a removal unit for removing the lubricant transferred onto the surface of the transfer target; and control information or temperature for image formation Predicting the transfer amount , which is the amount of the lubricant transferred onto the surface of the transfer object, based on the humidity, and the rotational speed of the removal roller and the more when it is predicted that the transfer amount of the lubricant is larger And a control unit that controls the operation of the removing unit so as to increase the speed difference from the rotational speed of the transfer target.

The control method of the image forming apparatus according to the present invention includes a step of transferring a toner image onto a surface of a rotatable transfer member, a contact with the surface of the transfer member, and transfer onto the surface of the transfer member. A step of removing the lubricant transferred onto the surface of the transfer object using a removing roller for removing the lubricant, and a drive unit that rotationally drives the removing roller, and control information for image formation or A step of predicting a transfer amount that is the amount of the lubricant transferred onto the surface of the transfer object based on temperature and humidity, and the rotation of the removing roller as the amount of transfer of the lubricant is predicted to be large And a step of controlling the operation of the removing step so as to increase the speed difference between the speed and the rotational speed of the transfer object.

A control program for an image forming apparatus according to the present invention includes a procedure for transferring a toner image onto a surface of a transferable member to be rotated by a computer mounted on the image forming apparatus, and abutting on the surface of the transfer target member, A procedure for removing the lubricant transferred onto the surface of the transferred body using a removing roller for removing the lubricant transferred onto the surface of the transferred body and a drive unit that rotationally drives the removing roller. And a procedure for predicting a transfer amount , which is the amount of the lubricant transferred onto the surface of the transfer object, based on control information for image formation or temperature / humidity, and the transfer amount of the lubricant is large. And the procedure of controlling the operation of the removal procedure so as to increase the speed difference between the rotation speed of the removal roller and the rotation speed of the transfer object.

  According to the present invention, it is possible to prevent creaking, slipping through, and poor cleaning of the intermediate transfer belt, and form a high-quality image.

1 is a schematic diagram illustrating a configuration example of an image forming apparatus 1 according to an embodiment of the present invention. Intermediate transfer belt 7 according to an embodiment of the present invention and a partially enlarged view of the periphery thereof The figure which illustrates the prediction table 161 which concerns on embodiment of invention It is a figure which shows the relationship between the transfer amount of the lubricant which concerns on embodiment of this invention to the intermediate transfer belt 7, and printing mode. The figure which illustrates the relationship between the transfer amount of the lubricant which concerns on embodiment of this invention, and rotational speed ratio Functional block diagram illustrating a control system according to an embodiment of the present invention 6 is a flowchart illustrating a method for controlling the image forming apparatus according to the embodiment of the invention. The figure which shows the result of the experiment 1 in a comparative example The figure which shows the result of the experiment 2 in a comparative example The figure which shows the result of the experiment 3 in a comparative example The figure which illustrates the prediction table which concerns on the modification 1 of the prediction process of this invention The functional block diagram which illustrates the control system concerning modification 1 of the prediction processing of the present invention The figure which illustrates the prediction table which concerns on the modification 2 of the prediction process of this invention The functional block diagram which illustrates the control system concerning modification 2 of the prediction processing of the present invention The figure which illustrates the press mechanism which concerns on the modification 1 of the adjustment process of this invention The figure which illustrates the press mechanism which concerns on the modification 1 of the adjustment process of this invention The figure which illustrates the relationship between the pressing force F which concerns on the modification 1 of the adjustment process of this invention, and the transfer amount M of a lubricant The functional block diagram which illustrates the control system concerning modification 1 of the adjustment processing of the present invention The figure which illustrates the relationship between the pressing force F and the transfer amount M of a lubricant according to Modification 1 of the adjustment process of the present invention These are the figures which show the relationship between the transfer amount of the lubricant and the band width of the toner according to the second modification of the adjustment processing of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
<Configuration example of image forming apparatus>
FIG. 1 is a schematic diagram illustrating a configuration example of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus 1 includes a document reading unit 2 and a main body unit G.

  The main body G includes the image processing unit 3 and four sets of writing units 4Y, 4M, 4C, 4K, and 4 corresponding to yellow (Y), magenta (M), cyan (C), and black (K), respectively. 4 sets of developing units 5Y, 5M, 5C, 5K, 4 sets of photosensitive drums 6Y, 6M, 6C, 6K, 4 sets of charging units 60Y, 60M, 60C, 60K, and 4 sets of lubricant application unit 61Y , 61M, 61C, 61K and four sets of cleaning blades 62Y, 62M, 62C, 62K as cleaning units.

  The main body G includes an intermediate transfer belt 7 as a transfer target, four sets of primary transfer rollers 8Y, 8M, 8C, and 8K respectively corresponding to Y, M, C, and K, a paper feed conveyance unit 9, A secondary transfer roller 10, a counter roller 11, a removal unit 12, a fixing unit 13, and a carry-out unit 14 are included.

  The image forming apparatus 1 is a digital multifunction peripheral (MFP) capable of monochrome printing and color printing by an electrophotographic method. The image forming apparatus 1 employs a tandem method using an intermediate transfer belt as a color image forming method.

  The image forming apparatus 1 has a color printing mode and a monochrome printing mode. Either printing mode is selected by the user or automatic control of the image forming apparatus 1. In the color printing mode, a color image is formed using toners of four colors Y, M, C, and K. The monochrome printing mode is for forming a monochrome image using black toner.

  The image forming apparatus 1 has a first input mode and a second input mode. The user selects a method for inputting image data such as a document. In the first input mode, the document D is scanned using the document reading unit 2 and image data is input. In the second input mode, for example, (digital) image data produced by a personal computer is captured from an external device of the image forming apparatus 1.

  The image forming apparatus 1 has a continuous printing mode in which printing is performed continuously, and an intermittent printing mode in which printing is performed one by one intermittently.

In the present embodiment, description will be made under the following assumptions.
The developer used in the image forming apparatus 1 is a two-component developer. The two-component developer is a developer containing toner and magnetic powder called a carrier.
It is assumed that the continuous printing mode is selected.

  The document reading unit 2 includes an auto document feeder (hereinafter, “ADF”) 2a and a scanning unit 2b.

  The ADF 2a conveys the document D set on the document table 2d onto the contact glass 2e of the scanning unit 2b using the conveyance roller 2c. In FIG. 1, the conveyance direction of the document D is illustrated by an arrow A.

  When the document D is transported onto the contact glass 2e by the ADF 2a, the scanning unit 2b irradiates the page (the surface on which the image is present) of the document D with light emitted from the light source 2f for each page of the document D. Scan. The scanning unit 2 b outputs an analog RGB signal as image data obtained by scanning to the image processing unit 3.

  The light source 2f is typically white light. By irradiating the original D with the light source 2f, the reflected light from the original D is imaged on a light receiving surface of a CCD (Charge Coupled Device) 2i through the mirror group 2g and the lens group 2h. The CCD 2 i photoelectrically converts the image of the light receiving surface and outputs an analog RGB signal obtained by the photoelectric conversion to the image processing unit 3.

  The image processing unit 3 includes, for example, a CPU (Central Processing Unit) and a storage device. The storage device includes, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), and a hard disk. The image processing unit 3 basically performs the following image processing.

  The image processing unit 3 A / D converts the analog RGB signal input from the scanning unit 2b into a digital RGB signal, and converts this into YMCK data. For example, the image processing unit 3 performs tone correction, shading correction, and the like using an LUT (Look Up Table) on the YMCK data according to user settings or initial settings. After the image processing, the image processing unit 3 outputs the YMCK data to the corresponding color writing units 4Y, 4M, 4C, and 4K.

  The writing units 4Y, 4M, 4C, and 4K differ only in the color components of YMCK data input from the image processing unit 3, and have the same structure. Hereinafter, the writing unit 4Y will be described.

  The writing unit 4Y includes, for example, a semiconductor laser, a polygon mirror, a scanning lens, and a mirror. In the exposure process, for example, the writing unit 4Y controls the semiconductor laser to blink the output of the laser light according to the change of the Y signal, and scans the surface of the photosensitive drum 6Y charged by the charging unit 60Y. An electrostatic latent image is formed.

  The development units 5Y, 5M, 5C, and 5K perform development using Y, M, C, and K component developers, respectively. The developing units 5Y, 5M, 5C, and 5K differ only in the toner color of the developer to be used and the corresponding writing units 4Y, 4M, 4C, and 4K, and have the same structure. Hereinafter, the developing unit 5Y will be described as an example.

  The developing unit 5Y includes a developing roller 51Y. The developing unit 5Y carries the toner on the surface of the developing roller 51Y, and develops the toner (that is, forms a toner image) by conveying the toner to an electrostatic latent image formed on the surface of the photosensitive drum 6Y.

  The photosensitive drums 6Y, 6M, 6C, and 6K are respectively formed with electrostatic latent images of Y, M, C, and K images on the surface thereof in the exposure process. The photosensitive drums 6Y, 6M, 6C, and 6K transfer the toner images to which the respective color toners adhere to the intermediate transfer belt 7 after the developing process.

  The photosensitive drums 6Y, 6M, 6C, and 6K include toner colors attached to the electrostatic latent image, corresponding developing units 5Y, 5M, 5C, and 5K, and corresponding writing units 4Y, 4M, 4C, and 4K. They are only different and the structure is the same. Hereinafter, the photosensitive drum 6Y will be described as an example.

  The photosensitive drum 6Y has photoconductivity and has a cylindrical shape. The diameter of the photosensitive drum 6Y is larger than the diameter of the developing roller 51Y. The photosensitive drum 6Y is disposed at a position in contact with and opposite to the developing roller 51Y so that the rotation axis thereof is parallel or substantially parallel to the rotation axis of the developing roller 51Y. The photosensitive drum 6Y rotates in the direction opposite to the rotation direction of the developing roller 51Y. In the present embodiment, the rotational speed of the photosensitive drum 6Y is constant.

  The intermediate transfer belt 7 is, for example, a polyimide seamless belt. The intermediate transfer belt 7 is suspended by a plurality of rollers including a counter roller 11 so as to be rotatable in the direction opposite to the rotation direction of the photosensitive drums 6Y, 6M, 6C, 6K. The intermediate transfer belt 7 is pressed from the back surface of the intermediate transfer belt 7 by the primary transfer rollers at the positions of the primary transfer rollers 8Y, 8M, 8C, and 8K. Hereinafter, the surface of the intermediate transfer belt 7 is assumed to be a contact surface with the photosensitive drums 6Y, 6M, 6C, and 6K.

  The primary transfer rollers 8Y, 8M, 8C, and 8K are arranged on the back side of the intermediate transfer belt 7 so that the intermediate transfer belt 7 can be crimped to the photosensitive drums 6Y, 6M, 6C, and 6K. A positive bias is applied to the primary transfer rollers 8Y, 8M, 8C, and 8K.

  The sheet feeding / conveying unit 9 includes a sheet feeding cassette 91. The paper feed cassette 91 stores the recording material SH. The paper feed conveyance unit 9 conveys the recording material SH accommodated in the paper feed cassette 91 to a transfer position (secondary transfer position) of the toner image by the secondary transfer roller 10 by a plurality of paper feed rollers. The recording material SH is typically paper.

  The secondary transfer roller 10 is disposed between the primary transfer roller 8K and the removing unit 12 with respect to the rotation direction of the intermediate transfer belt 7 so that the intermediate transfer belt 7 is sandwiched between the opposing rollers 11. After the primary transfer process, a positive bias is applied to the secondary transfer roller 10.

  The removing unit 12 is provided on the downstream side of the secondary transfer roller 10, that is, between the secondary transfer roller 10 and the photosensitive drum 6Y. The removing unit 12 removes the lubricant that has excessively transferred to the surface of the intermediate transfer belt 7. The removing unit 12 removes residual toner on the surface of the intermediate transfer belt 7.

  The fixing unit 13 includes a fixing roller 131 that is heated by a heat source, and a pressure roller 132 that is in pressure contact with the fixing roller 131. The fixing unit 13 fixes the toner image secondarily transferred to the recording material SH to the recording material SH by the heat and pressure of the fixing roller 131 and the pressure roller 132.

  The unloading unit 14 unloads the recording material SH on which the toner image is fixed by the fixing unit 13 to the outside of the image forming apparatus 1 using a plurality of rollers. When performing duplex printing, the carry-out unit 14 reverses the front and back of the recording material SH by the paper reversing unit 141 and conveys the reversed recording material SH to the secondary transfer position again.

  The basic operation of the image forming apparatus 1 is as follows.

  When the document reading unit 2 scans the document D, the image processing unit 3 A / D converts the analog RGB signal from the scan unit 2b into a digital RGB signal, and converts it into YMCK data. After the image processing, the image processing unit 3 outputs the YMCK data to the corresponding color writing units 4Y, 4M, 4C, and 4K. The writing units 4Y, 4M, 4C, and 4K respectively scan the surfaces of the photosensitive drums 6Y, 6M, 6C, and 6K with laser light in the exposure process.

  For example, a bias in which an AC voltage is superimposed on a DC voltage that is higher than the bias applied to the developing roller 51Y is applied to the photosensitive drum 6Y by the charging unit 60Y. By applying the bias, the entire surface of the photosensitive drum 6Y is uniformly charged to a negative potential. In the exposure process, an electrostatic latent image of a Y component image is formed on the surface of the photosensitive drum 6Y by scanning with the laser light emitted from the writing unit 4Y. In the developing step, toner moving from the surface of the developing roller 51Y adheres to the electrostatic latent image on the surface of the photosensitive drum 6Y due to a potential difference between the photosensitive drum and the developing roller 51Y, and the toner image Is formed. The same applies to other photosensitive drums.

  In the primary transfer process, when the intermediate transfer belt 7 is rotationally driven, toner images of Y, M, C, and K are sequentially transferred from the photosensitive drums 6Y, 6M, 6C, and 6K to the primary transfer rollers 8Y, 8M, At the positions 8C and 8K (primary transfer positions), transfer is performed so that the YMCK toner image is superimposed on the surface of the intermediate transfer belt 7. In the secondary transfer process, when the recording material SH is conveyed between the secondary transfer roller 10 and the opposing roller 11, a negatively charged color toner image is transferred from the surface of the intermediate transfer belt 7 onto the recording material SH. Is transcribed.

  In the cleaning process, the removing unit 12 removes residual toner on the surface of the intermediate transfer belt 7 using a cleaning blade. Further, residual toner on the surface of the photosensitive drum 6Y is removed by a cleaning blade 62Y as a cleaning unit that is in contact with the surface of the photosensitive drum 6Y.

<Lubricant application mechanism>
The lubricant is applied to facilitate cleaning of the photosensitive drum and the secondary transfer belt. Although the lubricant is not directly applied to the surface of the intermediate transfer belt, the lubricant is transferred from the photosensitive drum at the primary transfer position and the secondary transfer belt at the secondary transfer position. Here, a mechanism for applying the lubricant to the photosensitive drum and the secondary transfer belt will be described with reference to FIG.

  FIG. 2 is a partially enlarged view of the intermediate transfer belt 7 and its periphery. Lubricant application units 61Y, 61M, 61C, and 61K apply lubricants to the surfaces of the photosensitive drums 6Y, 6M, 6C, and 6K, respectively. The lubricant application unit 61 a applies a lubricant to the surface of the secondary transfer belt 101.

(A) Lubricant application mechanism to photosensitive drum 6Y A lubricant application mechanism to the photosensitive drum 6Y will be described. Since the lubricant application parts 61Y, 61M, 61C and 61K have the same configuration, the lubricant application part 61Y will be described.

  The lubricant application unit 61Y includes an application brush 611Y as a lubricant application body, a pressure spring 612Y, a lubricant 613Y, and a leveling blade 614Y. The lubricant application unit 61Y applies a lubricant to the surface of the photosensitive drum 6Y before the development process.

  The application brush 611Y rotates in the same direction as the rotation direction of the photosensitive drum 6Y. The application brush 611Y is in contact with the surface of the photosensitive drum 6Y, and the lubricant 613Y is pressed by the pressure spring 612Y. The application brush 611Y applies the lubricant 613Y attached to the brush to the surface of the photosensitive drum 6Y by the pressure of the pressure spring 612Y. An application roller can be used instead of the application brush 611Y.

  The pressure spring 612Y uses the elastic force of the spring to press the lubricant 613Y against the application brush 611Y with a constant pressing force, and supplies a certain amount of lubricant 613Y to the application brush 611Y.

  The lubricant 613Y is a fatty acid metal salt, for example, solid zinc stearate. The lubricant 613Y is not particularly limited as long as it can improve transferability and cleaning property of the photosensitive drum 6Y, such as barium stearate, metal oleate, and palmitic acid.

  The leveling blade 614Y is made of rubber, for example. The leveling blade 614Y is disposed on the downstream side with respect to the application brush 611Y in view of the rotation direction of the photosensitive drum 6Y. The cutting edge of the leveling blade 614Y is in contact with the surface of the photosensitive drum 6Y. The leveling blade 614Y uniformly levels the lubricant applied to the surface of the photosensitive drum 6Y by the application brush 611Y with respect to the rotation direction of the photosensitive drum 6Y.

  The operation of the coating mechanism is as follows. The pressure spring 612Y presses the lubricant 613Y against the application brush 611Y with a constant pressing force. By this pressing, a certain amount of lubricant 613 is supplied to the application brush 611Y. When the application brush 611Y applies the lubricant 613Y attached to the brush to the surface of the rotating photosensitive drum 6Y, the leveling blade 614Y uniformly leveles the lubricant with respect to the rotation direction of the photosensitive drum 6Y. .

  The cleaning blade 62Y is a leading type cleaning blade, and is made of, for example, rubber. The cleaning blade 62Y is not particularly limited as long as it is an elastic member such as polyurethane resin. In view of the rotation direction of the photosensitive drum 6Y, the cleaning blade 62Y is disposed on the upstream side with respect to the application brush 611Y. The cutting edge of the cleaning blade 62Y is in contact with the surface of the photosensitive drum 6Y with a contact angle α1. The cleaning blade 62Y removes residual toner on the surface of the photosensitive drum 6Y in the cleaning process.

(B) Mechanism for Applying Lubricant to Secondary Transfer Belt 101 A mechanism for applying lubricant to the secondary transfer belt 101 will be described. The lubricant application part 61a has the same configuration as the lubricant application part 61Y provided on the photosensitive drum 6Y. That is, the lubricant application unit 61a includes an application brush 611a, a pressure spring 612a, a lubricant 613a, and a leveling blade 614a. Then, a lubricant is applied on the secondary transfer belt 101 by driving the secondary transfer belt 101.

  The cleaning blade 62a is similar to the cleaning blade 62Y of the photosensitive drum 6Y, and removes toner and the like attached to the surface of the secondary transfer belt 101 from the intermediate transfer belt 7.

  The secondary transfer belt 101 is suspended by the secondary transfer roller 10 and rollers 102a and 102b so as to be rotatable in the direction opposite to the rotation direction of the intermediate transfer belt 7. The surface of the secondary transfer belt 101 is a surface facing the surface of the intermediate transfer belt 7.

  Note that the photosensitive drums 6Y, 6M, 6C, and 6K can freely contact and separate from the intermediate transfer belt 7 in accordance with the printing mode. For example, when the color printing mode is selected, all the photosensitive drums are in contact with the intermediate transfer belt 7. For example, when the monochrome printing mode is selected, only the black photosensitive drum 6 </ b> K contacts the intermediate transfer belt 7, and the other photosensitive drums are separated from the intermediate transfer belt 7.

  The intermediate transfer belt 7 is, for example, a seamless belt that uses polyimide as a base material. For example, an inorganic oxide layer is formed on the surface of the substrate (the contact surface with each photosensitive drum) so as to have releasability with respect to the toner. The intermediate transfer belt 7 is suspended by a counter roller 11, rollers 15a, 15b, 15c and 15d, and primary transfer rollers 8Y, 8M, 8C and 8K, and rotates clockwise.

  The removal unit 12 shown in FIG. 2 includes a cleaning blade 121 and a storage roller 122 as a removal roller.

  The cleaning blade 121 is a leading type cleaning blade, and is made of, for example, rubber. The cleaning blade 121 is not particularly limited as long as it is an elastic member such as polyurethane resin. The cutting edge of the cleaning blade 121 is in contact with the surface of the intermediate transfer belt 7 with a contact angle α2. The cleaning blade 121 removes residual toner on the surface of the intermediate transfer belt 7, particularly residual toner that could not be scraped off by the storage roller 122.

  The storage roller 122 is, for example, a rubber roller. The storage roller 122 is disposed on the upstream side with respect to the cleaning blade 121 in view of the rotation direction of the intermediate transfer belt 7. The surface of the storage roller 122 is in contact with the surface of the intermediate transfer belt 7. The storage roller 122 rotates in the direction opposite to the rotation direction of the intermediate transfer belt 7, and not only the residual toner on the surface of the intermediate transfer belt 7 but also the lubricant transferred to the surface of the intermediate transfer belt 7 toward the cleaning blade 121. Scrap out.

<Transition of lubricant to intermediate transfer belt 7>
For example, assume that the intermittent printing mode is selected in the monochrome printing mode. In this case, an image is formed on one recording material SH, and when the image is discharged, the developing roller 51K (see FIG. 1) of the developing unit 5K corresponding to the black photosensitive drum 6K temporarily stops its rotation. To do. The temporary stop of the developing roller 51K is a measure for minimizing the deterioration of the toner quality.

  On the other hand, the black photosensitive drum 6K continues to rotate. Meanwhile, the lubricant application unit 61K continues to apply the lubricant 613K to the surface of the photosensitive drum 6K. Since the photosensitive drum 6K is rotating, the lubricant applied to the surface of the photosensitive drum 6K is transferred from the surface of the photosensitive drum 6K to the surface of the intermediate transfer belt 7. Naturally, as the transfer of the lubricant proceeds, the amount of the lubricant accumulated on the surface of the intermediate transfer belt 7 gradually increases. As a result, the contact angle of the surface of the intermediate transfer belt 7 increases.

  When the color printing mode is selected, the surfaces of all the photosensitive drums come into contact with the surface of the intermediate transfer belt 7. Therefore, the amount of lubricant transferred to the surface of the intermediate transfer belt 7 is about four times that in the case of monochrome printing.

  For example, assume that the continuous printing mode is selected in a state where the contact angle is increased. In the continuous printing mode, the developing roller 51K of the developing unit 5K continues to rotate. The toner images formed on the surface of the photosensitive drum 6K are successively transferred onto the surface of the intermediate transfer belt 7 in the primary transfer process. Next, in the secondary transfer process, the toner image on the surface of the intermediate transfer belt 7 is transferred to the recording material SH.

  On the other hand, since the secondary transfer roller 10 continues to rotate, the secondary transfer belt 101 continues to rotate along with the rotation. During this time, the lubricant application unit 61a continues to apply the lubricant 613a to the surface of the secondary transfer belt 101.

  Since the back surface of the recording material SH is in contact with the surface of the secondary transfer belt 101, the lubricant transferred to the surface of the intermediate transfer belt 7 is removed by the recording material SH. As a result, the amount of lubricant on the surface of the intermediate transfer belt 7 gradually decreases, and the contact angle decreases. However, since the secondary transfer belt 101 rotates even when the recording material SH is not in the secondary transfer position, a part of the lubricant is transferred onto the intermediate transfer belt 7 at the secondary transfer position.

  Mekre tends to occur when the amount transferred to the lubricant on the surface of the intermediate transfer belt 7 is excessive. Specifically, it is known that meklet is likely to occur when the contact angle is high, typically just before the contact angle turns from increasing to decreasing. It is known that slip-through is likely to occur basically after the occurrence of meckle, that is, after the contact angle starts to decrease.

  Residual toner on the surface of the intermediate transfer belt 7 is scraped by the storage roller 122 from the upstream side toward the cleaning blade 121. The cleaning blade 121 removes residual toner that could not be scraped off by the storage roller 122. When the contact angle changes as described above, peeling and slipping occur, making it difficult for the cleaning blade 121 to remove residual toner.

  However, to what extent the lubricant is transferred to the intermediate transfer belt 7 under what conditions can be predicted to some extent. As described above, the transfer amount of the lubricant changes depending on the selection of the printing mode. If the transfer amount of the lubricant can be predicted, it is possible to control to increase the removal force of the lubricant so that the lubricant does not accumulate on the surface of the intermediate transfer belt 7. The image forming apparatus 1 selects the printing mode, specifically, the monochrome printing mode / color printing mode as a condition for changing the contact angle, and the transfer amount of the lubricant transferred to the surface of the intermediate transfer belt 7. Is predicted (prediction process).

  In order to suppress the accumulation of lubricant on the intermediate transfer belt 7, the rotational speed of the storage roller 122 may be increased with respect to the rotational speed of the intermediate transfer belt 7. As the latter rotational speed is higher than the former, the storage roller 122 can remove more lubricant. The image forming apparatus 1 adjusts the rotational speed of the storage roller 122 based on the prediction processing result, and increases the rotational speed difference of the storage roller 122 with respect to the intermediate transfer belt 7 (adjustment processing).

<Prediction process>
In the prediction process, a prediction table is used in which the condition for changing the contact angle is associated with the amount of lubricant transferred to the intermediate transfer belt 7. Hereinafter, the transfer amount of the lubricant to the intermediate transfer belt 7 is simply referred to as the lubricant transfer amount.

  FIG. 3 is a diagram illustrating a prediction table according to the embodiment of the present invention. FIG. 3 shows the amount of lubricant transfer for each printing mode in the intermittent printing mode. The transfer amount of the lubricant represents the ease of transfer as a level, and is a dimensionless amount. For example, “2” represents that the transfer amount of the lubricant is twice that of “1”.

Note that “HH”, “NN”, and “LL” represent the following.
HH: High temperature and humidity (Temperature around 30 degrees Celsius, Humidity around 80%)
NN: Medium temperature and medium humidity (Temperature around 20 degrees Celsius, Humidity around 50%)
LL: Low temperature and low humidity (temperature about 15 degrees Celsius, humidity about 20%)

  The amount of lubricant applied to the photosensitive drum 6Y and the secondary transfer belt 101 has a characteristic that it increases when the temperature is low and humidity is low. Therefore, in the monochrome printing mode, the transfer amount of the lubricant is “1” at high temperature and high humidity, “1.5” at medium temperature and medium humidity, and “2” at low temperature and low humidity.

  In the color printing mode, the four photosensitive drums are brought into contact with the surface of the intermediate transfer belt 7. Therefore, the transfer amount of the lubricant in the color print mode is four times the transfer amount in the monochrome print mode.

  FIG. 4 is a diagram showing the relationship between the amount of lubricant transfer and the printing mode according to the embodiment of the present invention. In the continuous printing mode, the number of printed sheets per unit time is larger than the number of printed sheets in the intermittent printing mode. The lubricant transferred to the surface of the intermediate transfer belt 7 is removed by the recording material SH that has been successively conveyed. That is, the transfer amount of the lubricant in the continuous printing mode is smaller than the transfer amount in the intermittent printing mode. Therefore, the transfer amount of the lubricant in the continuous printing mode is half of the transfer amount in the intermittent printing mode shown in FIG.

<Adjustment process>
In the adjustment process, the target rotational speed of the storage roller 122 is acquired based on the lubricant transfer amount obtained from the prediction table. Hereinafter, the target rotation speed will be described. FIG. 5 is a diagram illustrating the relationship between the amount of lubricant transfer and the rotational speed ratio according to the embodiment of the invention. The horizontal axis represents the amount of transfer (M) of the lubricant shown in FIGS. 3 and 4 respectively. The vertical axis represents the rotational speed ratio (R).

  In FIG. 5, the rotation speed ratio R is shown instead of the target rotation speed of the storage roller 122. The rotation speed ratio R is a value obtained by R = V2 / V1, where the rotation speed of the intermediate transfer belt 7 is V1 and the rotation speed of the storage roller 122 is V2.

  As the amount of lubricant transferred increases, the rotational speed of the storage roller 122 needs to be increased. Therefore, the rotational speed ratio R increases gently as the lubricant transfer amount increases. For example, at the lubricant transfer amount M = 8 (low temperature and low humidity in the color printing mode), the rotational speed ratio is R = 3.0. That is, the target rotation speed is 400 mm / s × 3 = 1200 mm / s.

<Control System of Image Forming Apparatus 1>
FIG. 6 is a functional block diagram illustrating the control system according to the embodiment of the invention. The control system shown in FIG. 6 includes an operation display unit 15, a first storage unit 16, a sensor unit 17, a control unit 18, and a second storage unit 19.

  The operation display unit 15 is configured with, for example, a touch panel. The operation display unit 15 outputs an instruction from the user to the control unit 18 as an instruction signal S1.

  The first storage unit 16 is a recording medium such as a ROM or a hard disk. The first storage unit 16 stores a prediction table 161 shown in FIGS. 3 and 4.

  The sensor unit 17 includes, for example, a temperature sensor and a humidity sensor. The sensor unit 17 measures the temperature and humidity inside the image forming apparatus 1 and outputs a measurement result S2 to the control unit 18.

  The control unit 18 includes, for example, a CPU (Central Processing Unit). The control unit 18 performs prediction processing and adjustment processing. Specifically, the control unit 18 reads the prediction table 161 stored in the first storage unit 16, and acquires the lubricant transfer amount from the instruction signal S1 and the measurement result S2.

  For example, it is assumed that the content of the user instruction is the color printing mode in the intermittent printing mode, and the temperature and humidity measured by the sensor unit 17 correspond to low temperature and low humidity (LL). In this case, the control unit 18 predicts that the lubricant transfer amount is “8” from the prediction table 161.

  The control unit 18 controls the rotation speed of the storage roller 122 based on the prediction process result S3. For example, when it is predicted that the lubricant transfer amount is “8”, the control unit 18 controls the rotation speed of the storage roller 122 to the target rotation speed (1200 mm / s).

  The second storage unit 19 is a recording medium such as a ROM or a hard disk, for example. The second storage unit 19 stores a control program 191. The control program 191 is a program in which a sequence of operations performed by the control system is written.

<Control Method of Image Forming Apparatus 1>
FIG. 7 is a flowchart illustrating a method for controlling the image forming apparatus according to the embodiment of the invention. Here, the photosensitive drum 6Y and the primary transfer roller 8Y are taken as an example.

  In the primary transfer process, the control unit 18 controls the photosensitive drum 6Y, the intermediate transfer belt 7, and the primary transfer roller 8Y, and transfers the toner image formed on the surface of the photosensitive drum 6Y to the surface of the intermediate transfer belt 7. (Step ST1).

  The controller 18 reads the prediction table 161 stored in the first storage unit 16 in order to predict the amount of lubricant transfer, and acquires the amount of lubricant transfer (step ST2).

  The control unit 18 controls the operation of the removal unit 12 based on the prediction processing result, specifically, the rotational speed of the storage roller 122 (step ST3).

  The storage roller 122 rotates at the rotational speed controlled by the control unit 18 and removes the lubricant transferred to the surface of the intermediate transfer belt 7 (step ST4).

  The above steps ST1 to ST4 are described in the control program 191 shown in FIG. 6 as a program executable by a computer.

<Comparative Example 1>
The inventors of the present application conducted the following experiment 1 in order to examine the effect of the adjustment process.

(Conditions for Experiment 1)
1. Intermediate transfer belt 7 rotational speed V1: 400 mm / s
2. 2. Recording material: A4 standard (210 mm × 297 mm) paper Original: 5% print rate
4). Print mode: Continuous print mode

  The inventors of the present application keep the rotational speed V1 of the intermediate transfer belt 7 constant and vary the rotational speed V2 of the storage roller 122, whereby the relationship between the rotational speed ratio R = V2 / V1 and the occurrence of the slip and slip-through is obtained. Examined. In Experiment 1, the inventors of the present application used the image forming apparatus 1 to copy a document with a printing rate of 5% on a total of 2000 recording materials. In printing, the 1-1000th print was performed in the color print mode. Printing on the 1001st and 2000th sheets was performed in a monochrome printing mode in which the contact angle was significantly increased. Then, the inventors of the present application investigated the presence or absence of mekre and the presence or absence of cleaning failure.

FIG. 8 is a diagram showing the results of Experiment 1 in the comparative example. The horizontal axis represents the amount of lubricant transferred. The vertical axis represents the rotation speed ratio. The symbols shown in FIG. 8 are as follows.
“◯”: No peeling or cleaning failure occurred.
“Δ”: Either a mesh or a cleaning failure occurred.
“X”: Meklet and cleaning failure occurred.

  The inventors of the present application have found that no meklet and cleaning failure occur when the rotational speed ratio R is equal to or greater than the characteristic curve C1. For example, when the lubricant transfer amount M = 8 (low temperature and low humidity in the color printing mode), when the rotation speed ratio R = 3.0, that is, V2 = 400 mm / s × 3 = 1200 mm / s, the peeling and the cleaning failure Did not occur. When the rotational speed ratio R is smaller than 3.0, a peeling or poor cleaning occurred. By rotating the storage roller 122 with a rotation speed ratio R that is equal to or higher than the characteristic curve C1, the lubricant transferred to the surface of the intermediate transfer belt 7 can be removed according to the transfer amount, and the change in the contact angle is suppressed. can do. The inventors of the present application obtained the target rotational speed of the storage roller 122 shown in FIG.

<Comparative Example 2>
The inventors of the present application conducted the following Experiment 2 and Experiment 3 in order to examine the effect of the image forming apparatus 1.

(Common conditions for Experiment 2 and Experiment 3)
1. 1. Recording material: A4 standard (210 mm × 297 mm) paper Original: 5% print rate
3. Environment: Low temperature and low humidity (temperature 15 degrees Celsius, humidity 20%)
4.1-1000th sheet: intermittent printing mode in color printing mode 5.1001-2000th sheet: continuous printing mode in monochrome printing mode

(Conditions for Experiment 2)
1. Intermediate transfer belt 7 rotational speed V1: 400 mm / s
2. Rotational speed V2 of storage roller 122: 800 mm / s

  Experiment 2 examined the change of the contact angle with respect to the running number when the rotation speed ratio was R = V2 / V1 = 2.0. The inventors of the present application used the image forming apparatus 1 to copy a document having a printing rate of 5% on a total of 2000 recording materials. In printing, the 1-1000th print was performed in the intermittent print mode in the color print mode. The 1001st to 2000th sheets were printed in the continuous printing mode in the monochrome printing mode. Then, the inventors of the present application investigated the presence or absence of mekle and slip-through.

(Conditions for Experiment 3)
1. Intermediate transfer belt 7 rotational speed V1: 400 mm / s
2. Rotation speed V2 of the storage roller 122: 1200 mm / s

  Experiment 3 is an examination of changes in the contact angle with respect to the running number when the rotation speed ratio is R = V2 / V1 = 3.0. Experiment 3 is the same as Experiment 2 except that the rotational speed ratio R is different.

  FIG. 9 is a diagram showing the results of Experiment 2 in Comparative Example 2. The horizontal axis indicates the number of running sheets. The vertical axis represents the contact angle. As shown in FIG. 9, in Experiment 2, the contact angle changed in the range of approximately 80 degrees to 105 degrees. Specifically, the contact angle gradually increased until the number of running sheets was 1-1000, and when the contact angle reached about 100 degrees, mekre occurred. When the printing mode was switched and the running number exceeded 1000 sheets, the contact angle decreased sharply from the maximum of 105 degrees, and when the contact angle reached about 92 degrees, slip-through occurred. When the rotational speed ratio R is smaller than the characteristic curve C1 shown in FIG. 8, the contact angle of the surface of the intermediate transfer belt 7 is greatly changed, and peeling and slipping occur.

  FIG. 10 is a diagram illustrating the results of Experiment 3 in Comparative Example 2. As shown in FIG. 10, in Experiment 3, the contact angle changed in the range of approximately 80 to 84 degrees. The contact angle is small compared to the result of Experiment 2. Although the contact angle increased up to the 1-1000th running number, the increase was small and did not exceed 84 degrees. When the running number exceeded 1000, the contact angle decreased slowly compared to the result of Experiment 2. In Experiment 3, there was no sudden change in the contact angle, so no meklet and slip-through occurred.

  As described above, it is possible to prevent the lubricant from accumulating on the intermediate transfer belt by predicting the transfer amount of the lubricant in advance according to the printing mode conditions and adjusting the rotation speed of the storage roller 122. can do. As a result, it is possible to prevent melee, slip-through, and poor cleaning of the intermediate transfer belt 7, and a high-quality image can be formed.

<Variation 1 of prediction processing>
A first modification of the prediction process will be described. In the first modification of the prediction process, the prediction process is performed using the rotation distances of the developing rollers 51Y, 51M, 51C, and 51K. Here, a case where the monochrome printing mode is selected in the intermittent printing mode will be described as an example. Further, the developing roller 51K corresponding to the black photosensitive drum 6K is taken as an example.

  FIG. 11 is a diagram illustrating a prediction table according to the first modification of the prediction process of the present invention. As shown in FIG. 11, the transfer amount of the lubricant is related to the rotation distance of the developing roller 51K. FIG. 11 shows a ratio R1 = L2 / L1 of the rotation distance L2 with respect to the rotation distance L1 when the rotation distance of the photosensitive drum 6K is L1 and the rotation distance of the developing roller 51 is L2.

  In the monochrome printing mode, only the black photosensitive drum 6 </ b> K is in contact with the surface of the intermediate transfer belt 7 among all the photosensitive drums. While printing is stopped, the black photosensitive drum 6K is rotating, but the developing roller 51K is stopped. The ratio R1 = 0 indicates that the rotation of the developing roller 51K is stopped.

  While the rotation of the developing roller 51K is stopped, the amount of lubricant transferred from the photosensitive drum 6K to the intermediate transfer belt 7 is increased as compared with the case where the developing roller 51K is rotating. On the other hand, while printing is being performed and the developing roller 51K is rotating, the lubricant on the surface of the photosensitive drum 6K is scraped to some extent by the developing roller 51K. Therefore, as the ratio R1 increases, the amount of lubricant transfer decreases. As described above, the amount of lubricant transferred is greater at low temperature and low humidity than at high temperature and high humidity. In the case of the color printing mode, the amount of transfer of each lubricant shown in FIG. 11 may be doubled.

  FIG. 12 is a functional block diagram illustrating a control system according to the first modification of the prediction process of the present invention. The first storage unit 16 stores a prediction table 161a illustrated in FIG. In FIG. 12, parts common to those in FIG. 6 are denoted by the same reference numerals and description thereof is omitted.

  The control unit 18 reads the prediction table 161a stored in the first storage unit 16, and acquires the rotation distance L1 of the photosensitive drum 6K and the rotation distance L2 of the developing roller 51. Note that the control unit 18 acquires the rotation distances L1 and L2 for each job. The controller 18 controls the rotational speed of the storage roller 122 from the amount of lubricant transferred in the prediction table 161a corresponding to the ratio R2 = L2 / L3.

  In the first modification of the prediction process, the transfer amount of the lubricant is predicted using the ratio R1, and the rotation speed of the storage roller 122 is adjusted according to the prediction result. Therefore, the occurrence of meklet and slip-through can be suppressed. As a result, the cleaning failure of the intermediate transfer belt 7 can be prevented, and as a result, a high-quality image can be formed.

<Modification 2 of prediction processing>
A second modification of the prediction process will be described. In the second modification example of the prediction process, the prediction process is performed by using the rotation distances of the application brushes 611Y, 611M, 611C, and 611K. Here, a case where the monochrome printing mode is selected in the intermittent printing mode will be described as an example. An application brush 611K corresponding to the black photosensitive drum 6K is taken as an example.

  FIG. 13 is a diagram illustrating a prediction table according to the second modification of the prediction process of the present invention. As shown in FIG. 13, the transfer amount of the lubricant is related to the rotation distance of the application brush 611K. FIG. 13 shows a ratio R2 = L2 / L3 of the rotation distance L3 with respect to the rotation distance L2 of the developing roller 51K, where L3 is the rotation distance of the application brush 611K.

  The application brush 611K rotates regardless of the printing mode so as to apply a lubricant to the photosensitive drum 6K. Therefore, the ratio R2 = 0 means that the developing roller 51K is stopped. From the same viewpoint as the first modification of the prediction process, the amount of lubricant transferred is large while the application brush 611K is stopped. As the ratio R2 increases, the amount of lubricant transfer decreases. The amount of lubricant transferred is greater at low temperature and low humidity than at high temperature and humidity. In the case of the color printing mode, the amount of transfer of each lubricant shown in FIG. 13 may be doubled.

  FIG. 14 is a functional block diagram illustrating a control system according to the second modification of the prediction process of the present invention. The first storage unit 16 stores a prediction table 161b illustrated in FIG. In FIG. 14, parts common to those in FIG.

  The control unit 18 reads the prediction table 161b stored in the first storage unit 16, and acquires the rotation distance L2 of the developing roller 51K and the rotation distance L3 of the application brush 611K. Note that the control unit 18 acquires the rotation distances L2 and L3 for each job. The controller 18 controls the rotational speed of the storage roller 122 from the amount of lubricant transferred in the prediction table 161b corresponding to the ratio R2 = L2 / L3.

  In the second modification of the prediction process, the transfer amount of the lubricant is predicted using the ratio R2, and the rotation speed of the storage roller 122 is adjusted according to the prediction result. Therefore, the occurrence of meklet and slip-through can be suppressed. As a result, the cleaning failure of the intermediate transfer belt 7 can be prevented, and as a result, a high-quality image can be formed.

<Modification 3 of prediction processing>
A third modification of the prediction process will be described. In the third variation of the prediction process, the prediction process is performed based on the usage time of the application brushes 611Y, 611M, 611C, and 611K. Here, a case where the monochrome printing mode is selected in the intermittent printing mode will be described as an example. An application brush 611K corresponding to the black photosensitive drum 6K is taken as an example.

  The application brush 611K tends to fall down as the usage time becomes longer. The falling of the brush causes application of an excessive lubricant to the photosensitive drum 6K.

  In the third variation of the prediction process, the control unit 18 shown in FIG. 14 measures the usage time of the application brush 611K and controls the rotation speed of the storage roller 122 according to the measurement time. The controller 18 predicts that the amount of lubricant transfer increases as the measurement time increases, and adjusts the rotational speed of the storage roller 122 to increase as the measurement time increases.

  In the third variation of the prediction process, the amount of lubricant transfer is predicted based on the usage time of the application brush 611K, and the rotational speed of the storage roller 122 is adjusted according to the prediction result. Therefore, the occurrence of meklet and slip-through can be suppressed. As a result, the cleaning failure of the intermediate transfer belt 7 can be prevented, and as a result, a high-quality image can be formed.

<Modification 1 of Adjustment Process>
A modification example 1 of the adjustment process will be described. In the first modification of the adjustment process, the amount of lubricant transferred to the intermediate transfer belt 7 is adjusted by pressing the storage roller 122 against the intermediate transfer belt 7. Here, a case where the monochrome printing mode is selected in the intermittent printing mode will be described as an example.

  A pressing mechanism for pressing the storage roller 122 against the intermediate transfer belt 7 will be described. FIG. 15 is a diagram illustrating a pressing mechanism according to Modification 1 of the adjustment process of the present invention. FIG. 15 shows a peripheral portion of the removal unit 12. The pressing mechanism includes a spring support plate 123, a spring 124, a spring pressing plate 125, and a cam 126.

  The spring support plate 123 is locked on a rotating shaft 1221 protruding from the storage roller 122 so as to be parallel or substantially parallel to the intermediate transfer belt 7. The spring support plate 123 supports the spring 124.

  The spring 124 is, for example, a helical spring. The spring 124 is positioned on the spring support plate 123 so that the expansion / contraction direction is perpendicular to the contact surface between the storage roller 122 and the intermediate transfer belt 7.

  The spring pressing plate 125 is supported on the upper part of the spring 124.

  The cam 126 has an elliptical cross section. The cam 126 rotates clockwise with respect to the rotation shaft 1261. Note that the cam 126 may rotate counterclockwise. In the cam 126, the rotation shaft 1261 is parallel to the contact surface between the storage roller 122 and the intermediate transfer belt 7, and contacts the surface opposite to the surface that contacts the spring 124 of the spring pressing plate 125. The cam 126 presses the spring 124 in the vertical direction of the intermediate transfer belt 7 when the long axis is perpendicular to the surface of the spring pressing plate 125 due to rotational movement. On the other hand, the cam 126 stops the pressing of the spring 124 when the long axis is parallel to the surface of the spring pressing plate 125.

  The operation of the pressing mechanism is as follows. As shown in FIG. 15, the cam 126 rotates clockwise and stops pressing the spring 124 when the long axis is parallel to the surface of the spring pressing plate 125. In this case, since the cam 126 does not press the spring 124, the storage roller 122 does not press the intermediate transfer belt 7.

  FIG. 16 is a diagram illustrating a pressing mechanism according to Modification 1 of the adjustment process of the present invention. In FIG. 16, the same reference numerals are given to the portions common to FIG. 15. As shown in FIG. 16, the cam 126 causes the spring pressing plate 125 to press the spring 124 when the long axis is perpendicular to the surface of the spring pressing plate 125. The pressing force by the spring 124 is transmitted to the rotating shaft 1221 of the storage roller 122 via the spring support plate 123. As a result, the storage roller 122 presses the intermediate transfer belt 7 in the vertical direction.

  When the long axis is perpendicular to the surface of the spring pressing plate 125, the pressing force from the storage roller 122 to the intermediate transfer belt 7 becomes maximum. In FIG. 16, the pressing force F from the storage roller 122 to the intermediate transfer belt 7 is indicated by an arrow. The pressing force F can be adjusted by controlling the rotation of the cam 126.

  FIG. 17 is a diagram illustrating the relationship between the pressing force and the amount of lubricant transfer according to the first modification of the adjustment process of the invention. The pressing force is a force acting from the storage roller 122 to the intermediate transfer belt 7. The horizontal axis shows the amount of lubricant transfer (M). The vertical axis represents the pressing force (F, unit is N).

  As shown in FIG. 17, the pressing force F from the storage roller 122 to the intermediate transfer belt 7 is related to the lubricant transfer amount so as to increase as the lubricant transfer amount increases. For example, when the transfer amount of the lubricant is “6”, the pressing force is approximately 19N. The range in which the pressing force can be taken is a range in which the storage roller 122 can easily remove the lubricant.

  FIG. 18 is a functional block diagram illustrating a control system according to the first modification of the adjustment process of the invention. In FIG. 18, parts common to those in FIG. 6 are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 18, the control unit 18 controls the rotation of the cam 126 based on the prediction processing result S3. Specifically, the control unit 18 controls the rotation of the cam 126 so that the storage roller 122 presses the intermediate transfer belt 7 with a pressing force corresponding to the amount of lubricant transfer obtained from the prediction processing result S3. When the cam 126 rotates under the control of the control unit 18, the storage roller 122 presses the intermediate transfer belt 7 in accordance with the rotation.

<Comparative Example 4>
FIG. 19 is a diagram illustrating the relationship between the pressing force F and the amount of lubricant transfer according to the first modification of the adjustment process of the invention. The horizontal axis shows the amount of lubricant transfer (M). The vertical axis represents the pressing force (F).

  The inventors of the present application conducted an experiment with the same content as Experiment 1 for Modification Example 1 of the adjustment process. As a result, the inventors of the present application have found that no meklet and cleaning failure occur when the pressing force F is equal to or higher than the characteristic curve C2.

  For example, when the lubricant transfer amount M = 8 (low temperature and low humidity in the color printing mode), the pressing force is approximately 19N. When the storage roller 122 presses the intermediate transfer belt 7 with the pressing force F = 19 N by the pressing mechanism, the area of the contact portion between the intermediate transfer belt 7 and the storage roller 122 increases, and the removal force of the lubricant by the storage roller 122 increases. Therefore, the change in the contact angle can be suppressed to the minimum, and the occurrence of melee and slip-through can be suppressed. As a result, the cleaning failure of the intermediate transfer belt 7 can be prevented, and as a result, a high-quality image can be formed. The inventors of the present application obtained the pressing force shown in FIG. 17 based on the experimental results.

<Modification 2 of Adjustment Process>
A modification example 2 of the adjustment process will be described. In the second modification of the adjustment process, the toner transferred onto the surface of the intermediate transfer belt 7 as a patch image is removed, and the toner transferred to the surface of the intermediate transfer belt 7 is removed together with the toner. This is a phenomenon. Here, a case where the monochrome printing mode is selected in the intermittent printing mode will be described as an example.

  FIG. 20 is a diagram illustrating the relationship between the amount of lubricant transfer and the toner band width according to the second modification of the adjustment process of the invention. The horizontal axis shows the amount of lubricant transfer (M). The vertical axis represents the toner band width (unit: mm) in the circumferential direction on the intermediate transfer belt.

  The inventors of the present application directly formed toner between the recording materials in which the toner is conveyed on the intermediate transfer belt as a patch image every time a predetermined number of sheets (for example, 10 sheets) are printed. At that time, the inventors of the present application changed the width of the toner, that is, the interval between the recording materials in the circumferential direction of the intermediate transfer belt 7 in accordance with the amount of lubricant transferred based on the prediction process.

  As a result, the present inventors have found that no cleaning failure occurs when the toner band width is equal to or greater than the characteristic curve C3. For example, when the amount of lubricant transfer M = 8 (low temperature and low humidity in the color printing mode), it is desirable that the toner band width is approximately 20 mm or more.

  Even if the toner as a patch image is directly formed on the intermediate transfer belt with a band width that is equal to or greater than the characteristic curve C3, the change in the contact angle can be minimized, and the occurrence of peeling and slipping can be prevented. . As a result, the cleaning failure of the intermediate transfer belt 7 can be prevented, and as a result, a high-quality image can be formed.

  Various combinations of the modification examples of the prediction process and the adjustment process described above are possible including the embodiment. For example, the amount of lubricant transfer is predicted using the rotation distances of the developing rollers 51Y, 51M, 51C, and 51K (prediction processing modification 1), and the storage roller 122 is pressed against the intermediate transfer belt 7, thereby the lubricant. The amount of transfer to the intermediate transfer belt 7 can be adjusted (variation example 1 of the adjustment process).

The present invention can be variously modified without departing from the gist thereof.
The present invention can be applied to a transfer drum type image forming apparatus. In the transfer drum system, an intermediate transfer drum is used instead of the intermediate transfer belt as the transfer target portion of the present invention.
In the present embodiment, the two-component developer is described as an example of the developer, but the effects of the present invention can be obtained even when a one-component developer is used instead of the two-component developer. Note that the one-component developer is made of magnetic toner.

  The storage location of the control program 191 is not limited to the second storage unit 19. The control program 191 may be stored in the first storage unit 16. If the control unit 18 can read the control program 191 when it is used, the control program 191 may be stored in a recording medium outside the image forming apparatus 1, for example, a flash memory.

  In the present embodiment, a digital multi-function peripheral has been exemplified as the image forming apparatus 1, but the present invention can be applied to, for example, a general-purpose printer in addition to the digital multi-function peripheral. Furthermore, when used as a replacement for a printing press and used in an image forming apparatus for production printing that requires high image quality and productivity, a greater effect can be obtained.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 6Y, 6M, 6C, 6K Photosensitive drum 7 Intermediate transfer belt 8Y, 8M, 8C, 8K Primary transfer roller 10 Secondary transfer roller 11 Opposing roller 12 Removal part 121 Cleaning blade 122 Storage roller 15 Operation display part 16 First storage unit 17 Sensor unit 18 Control unit 19 Second storage unit 61Y, 61M, 61C, 61K, 61a Lubricant application unit 611Y, 611M, 611C, 611K, 611a Application brush 612Y, 612M, 612C, 612K, 612a Pressure spring 613Y, 613M, 613C, 613K, 613a Lubricant 614Y, 614M, 614C, 614K, 614a Leveling blade 62Y, 62M, 62C, 62K, 62a Cleaning blade 101 Secondary transfer belt

Claims (11)

A rotatable transfer member on which a toner image and a lubricant are carried; and
A removal roller that contacts the surface of the transfer body and removes the lubricant transferred onto the surface of the transfer body; and a drive unit that rotationally drives the removal roller. A removal section for removing the lubricant transferred onto the surface of
When predicting the transfer amount , which is the amount of the lubricant transferred onto the surface of the transfer object, based on control information for image formation or temperature / humidity, and predicting that the transfer amount of the lubricant is large A control unit for controlling the operation of the removing unit so as to increase the speed difference between the rotational speed of the removal roller and the rotational speed of the transfer target;
An image forming apparatus. A photoreceptor carrying the toner image to be transferred to the transfer object;
A lubricant application part for applying the lubricant to the photoreceptor;
A primary transfer portion that transfers the toner image on the photoreceptor to the transfer target;
The controller predicts a transfer amount of the lubricant transferred from the photoconductor to the transfer target at a position where the toner image is transferred from the photoconductor to the transfer target by the primary transfer unit. To
The image forming apparatus according to claim 1. A secondary transfer portion for transferring the toner image carried on the transfer object to a recording material;
A lubricant application part that applies the lubricant to the secondary transfer part,
The control unit is configured to transfer the lubricant transferred from the secondary transfer unit to the transfer target at a position where the toner image is transferred from the transfer target to the recording material by the secondary transfer unit. Predict,
The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the control unit predicts that the lower the temperature and the humidity, the more the amount of lubricant transferred. The control unit predicts that the amount of transfer of the lubricant is larger in the intermittent printing mode in which printing is performed intermittently than in the continuous printing mode in which printing is performed continuously.
The image forming apparatus according to claim 1. The controller predicts that the amount of lubricant transferred is greater in the color printing mode than in the monochrome printing mode;
The image forming apparatus according to claim 1. A developing roller for developing the photoreceptor with toner;
The control unit predicts that the lubricant transfer amount is larger as the rotation distance of the developing roller is shorter.
The image forming apparatus according to claim 2. The lubricant application unit applies the lubricant by rotating in contact with the photoreceptor,
The control unit predicts that the amount of transfer of the lubricant is larger as the rotation distance of the developing roller relative to the rotation distance of the lubricant application unit is shorter.
The image forming apparatus according to claim 2. The lubricant application unit includes a brush member that applies the lubricant by rotating in contact with the photoreceptor,
The control unit predicts that the amount of transfer of the lubricant is larger as the usage time of the brush member is longer.
The image forming apparatus according to claim 2. A step of transferring a toner image onto the surface of a rotatable transfer target;
A surface of the transfer body using a removal roller that contacts the surface of the transfer body and removes the lubricant transferred onto the surface of the transfer body, and a drive unit that rotationally drives the removal roller. Removing the lubricant transferred above;
Predicting a transfer amount that is the amount of the lubricant transferred onto the surface of the transfer object based on control information for image formation or temperature and humidity;
Controlling the operation of the removing step so as to increase the speed difference between the rotational speed of the removal roller and the rotational speed of the transfer object as predicted to have a larger transfer amount of the lubricant;
A method for controlling an image forming apparatus. In the computer mounted on the image forming device,
A procedure for transferring a toner image onto the surface of a rotatable transfer target;
A surface of the transfer body using a removal roller that contacts the surface of the transfer body and removes the lubricant transferred onto the surface of the transfer body, and a drive unit that rotationally drives the removal roller. Removing the lubricant transferred above;
A procedure for predicting a transfer amount , which is the amount of the lubricant transferred onto the surface of the transfer object, based on control information for image formation or temperature and humidity;
A procedure for controlling the operation of the removal procedure so as to increase the speed difference between the rotational speed of the removal roller and the rotational speed of the transfer body as the amount of transfer of the lubricant is predicted to be large;
Control program to execute

Images