JP2012234125A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can acquire high accuracy color registration correction data during a color registration adjusting mode and can execute the color registration adjusting mode with high accuracy.SOLUTION: The image forming apparatus includes: an image forming part 80, which includes a driving part 64 that drives an endless intermediate transfer belt 6 to circulate and a plurality of image forming units 10Y, 10M, 10C and 10K for forming images of the respective colors, and which forms a color image by superposing the images formed by the image forming units onto the intermediate transfer belt 6 circulated by the driving part 64; a control part 15, which sets a normal operation mode or a color registration adjusting mode on the image forming part 80; and an oscillating part 65, which oscillates the intermediate transfer belt 6 in a width direction at a first moving speed of Vx=V1 responding to the setting of the normal operation mode and which oscillates the intermediate transfer belt 6 in the width direction at a second moving speed Vx=V2 that is lower than the first moving speed Vx=V1, responding to the setting of the color registration adjusting mode.

Description

  The present invention can be applied to a color printer having a belt steering control function for correcting a deviation of the intermediate transfer belt in correspondence with the normal operation mode and the color registration adjustment mode, a copying machine, a multifunction machine, and the like. The present invention relates to an apparatus and an image forming method.

  In recent years, there have been color printers that form color images based on color image information, color copiers that have a scan function that reads an image of an original and outputs an image signal for color image reproduction, and multifunction devices. It has been increasingly used. For example, digital color printers that form color images based on red (R), green (G), and blue (B) image data from external devices such as personal computers are widely used.

  In this type of printer, according to a color printer that employs an electrophotographic system, yellow (Y), magenta (M), cyan (C), and black (BK) after color conversion of RGB image data is performed. ) An image forming unit for forming a color toner image based on the color image data is provided. The image forming unit includes image forming units that share image forming output functions of Y, M, C, and BK colors, and image data is applied to a photosensitive drum uniformly charged by a charger for each image forming color. Based on the above, an electrostatic latent image is formed by a scanning exposure unit using a polygon mirror or the like.

  This electrostatic latent image is developed by a developing device for each image forming color. The color toner image formed on the photosensitive drum after being charged, exposed and developed in this manner is superimposed on, for example, an intermediate transfer belt, and the superimposed color toner image is transferred onto a sheet by a transfer unit. The The sheet is transported from the sheet feeding tray to the transfer section by the sheet feeding section. The toner image transferred onto the predetermined transfer material is fixed by the fixing unit. As a result, a color image based on the image data can be formed on a predetermined sheet.

  According to this type of color printer, a belt steering control mechanism that corrects the deviation of the intermediate transfer belt, a normal operation mode, and a color registration adjustment mode are provided. In the normal operation mode, the belt steering control mechanism forms a color image on the intermediate transfer belt while swinging the intermediate transfer belt in the width direction at a predetermined moving speed, and transfers the color image onto a predetermined sheet. Made. Also in the color registration adjustment mode, a printed image for color misregistration correction is formed on the intermediate transfer belt while swinging the intermediate transfer belt in the width direction at the same movement speed, that is, the same movement speed as in the normal operation mode. The printed image is read by a predetermined detection unit to calculate the color misregistration amount.

  In connection with the above-described swinging of the intermediate transfer belt in the width direction, Patent Document 1 discloses an image forming apparatus. According to this image forming apparatus, when forming a color image by superimposing the images of the respective colors formed by the plurality of image forming units on an endless transfer belt that circulates, the image forming unit, the first and second image forming units. A detection unit, a deviation correction unit, a movement unit, and a control unit are provided.

  The first detection unit detects a test image for color misregistration correction formed on the transfer belt. The second detection unit detects the position in the width direction of the transfer belt. The moving unit moves the transfer belt in the width direction. The deviation correction unit corrects the deviation of the transfer belt by controlling the moving unit according to the detection value of the second detection unit.

  The control unit forms a test image on the transfer belt by the image forming unit during color registration correction, and then detects the test image on the transfer belt by the first detection unit, and forms each image according to the detection result. The image forming position by the part is corrected. When the control unit performs the deviation correction during the color registration correction, the second detection is performed during the period from the start of the test image formation on the transfer belt to the detection of the test image by the first detection unit. The movement amount of the transfer belt detected by the section is compared with a reference value.

  Based on these assumptions, when the movement amount of the transfer belt is equal to or less than the reference value, the control unit corrects the correction amount according to the movement amount and performs color registration correction. Color registration correction was stopped when the amount of movement exceeded the reference value. When the image forming apparatus is configured in this way, not only color registration correction and transfer belt offset correction can be performed simultaneously, but also color registration correction can be prevented when the transfer belt is unstable.

  Further, in relation to the above-described swinging of the intermediate transfer belt in the width direction, Patent Document 2 discloses an image forming apparatus. According to this image forming apparatus, when the toner image formed on the image carrier is transferred to the recording medium via the intermediate transfer belt constituted by the endless belt member, the image carrier, the belt speed / deviation detecting means And an image forming position correcting unit, and a belt speed / shift detection unit detects the speed of the intermediate transfer belt and a shift in the main scanning direction. The image forming position correcting unit corrects the image forming position on the image carrier in the main scanning direction.

  Based on these assumptions, detection marks for belt meandering detection are provided at regular intervals in the sub-scanning direction on the endless belt, and the belt speed / deviation detection means detects the movement of the detection mark in the sub-scanning direction. Then, the belt speed is detected, and the belt shift is detected by detecting the movement of the detection mark in the main scanning direction.

  At the same time, the belt speed / deviation detection means is a plurality of detection marks arranged in the sub-scanning direction of the endless belt, and the positions of the detection marks detected by the belt speed / deviation detection means are different from the main scanning direction. Thus, the movement of the detection mark in the sub-scanning direction is detected, and based on the movement of the detection mark, the image forming position correcting unit corrects the image forming position in the main scanning direction. By configuring the apparatus in this way, the image forming position in the main scanning direction can be corrected based on the detection result of the skew direction and the skew amount of the endless belt, so image distortion and color misregistration due to image position shift in the main scanning direction. Can be prevented.

Japanese Patent Laying-Open No. 2010-164598 (FIG. 2 on page 6) JP 2010-217300 A (page 10 FIG. 8)

  However, the conventional image forming apparatus has the following problems.

  i. When shifting from the normal operation mode to the color registration adjustment mode and when the moving speed in the width direction of the intermediate transfer belt is set large by the belt steering control mechanism, A method is adopted in which the registration adjustment mode is stopped and the transfer belt is moved until the moving amount becomes small. According to this method, the time required for adjusting the moving speed of the intermediate transfer belt in the width direction by the belt steering control mechanism becomes long, or the adjustment of the moving speed does not end within a certain time and an error occurs. There is a problem that the productivity of the image forming apparatus is reduced.

  ii. By the way, when the color registration adjustment mode is executed with the amount of movement in the width direction of the intermediate transfer belt set to a large value, an image with the color registration shifted may be output in the normal operation mode. There is. In this case, since the user does not know the color misregistration correction amount (level) in advance, it is necessary to readjust the color resist after confirming the image on the printed recording paper. As a result, there is a problem that the printed recording paper and the time for resetting are wasted.

  iii. Further, in the color registration adjustment mode, a color misregistration correction printed image is formed on the intermediate transfer belt while the intermediate transfer belt is swung in the width direction at the same moving speed as in the normal operation mode. For this reason, the printed image is read in a state where the intermediate transfer belt (hereinafter, also simply referred to as a transfer belt) is short compared to the case where the oscillation cycle due to the moving speed in the width direction is long. The position detection signal of the printed image read in a state where the oscillation cycle is short includes a lot of wobbling components, and the color misregistration correction data includes an error due to the wobbling component when calculating the color misregistration amount. There is a problem that it ends up. Accordingly, there is a problem that a highly accurate (good) correction value such as a positional deviation in the main scanning direction, a positional deviation in the sub-scanning direction, an image inclination, and a magnification cannot be obtained.

  Accordingly, the present invention solves the above-described problems, and devise movement control in the width direction of the transfer belt so that high-precision color registration correction data can be acquired in the color registration adjustment mode. An object of the present invention is to provide an image forming apparatus and an image forming method which can execute the color registration adjustment mode well.

  In order to solve the above-described problem, an image forming apparatus according to claim 1 includes an endless transfer belt, a drive unit that drives the transfer belt to circulate, and a plurality of image forming units that form images of each color. An image forming unit for forming a color image by superimposing an image formed by the image forming unit on the transfer belt circulated by the driving unit, and an end position in the width direction of the transfer belt. A first detection unit for detecting, a second detection unit for detecting a color misregistration correction printed image formed on the transfer belt, and swinging the transfer belt in the width direction at a first moving speed; An operation in which the first detection unit forms the color image on the transfer belt while detecting the end position in the width direction of the transfer belt, and transfers the color image to a predetermined sheet material is a normal operation mode. Then, the transfer belt is swung in the width direction at a second movement speed that is slower than the first movement speed in the normal operation mode, and the end portion in the width direction of the transfer belt is detected by the first detection unit. When the color registration adjustment mode is set to the operation of forming a color misregistration correction printed image on the transfer belt while detecting the position, and reading the printed image by the second detection unit to calculate the color misregistration amount, A setting unit configured to set the normal operation mode or the color registration adjustment mode in the image forming unit; and the transfer belt is swung in the width direction at the first moving speed according to the setting of the normal operation mode; And an oscillating portion that oscillates the transfer belt in the width direction at a second movement speed that is slower than the first movement speed in accordance with the setting of the adjustment mode.

  According to the image forming apparatus of the first aspect, the image forming unit includes an endless transfer belt, a drive unit that drives the transfer belt to circulate, and a plurality of image forming units that form images of the respective colors. doing. The image forming unit forms a color image by superimposing the image formed by the image forming unit on a transfer belt circulated by the driving unit. The second detection unit detects a color misregistration correction printed image formed on the transfer belt. The first detection unit detects the end position of the transfer belt in the width direction. The setting unit sets a normal operation mode or a color registration adjustment mode in the image forming unit. The swing unit swings the transfer belt in the width direction at the first moving speed according to the setting of the normal operation mode. The swing unit swings the transfer belt left and right in the width direction at a second moving speed that is slower than the first moving speed in accordance with the setting of the color registration adjustment mode.

  By this swinging, the color registration adjustment mode can be performed in a state where the moving speed in the width direction of the transfer belt is kept small, so that highly accurate registration correction data can be obtained. As a result, a high-quality and high-definition color image can be formed.

  According to a second aspect of the present invention, the image forming apparatus according to the first aspect further includes a storage unit that stores information on a plurality of movement speeds for setting a movement speed in the swing unit, and the setting unit includes the first setting unit. The detection information of the end position of the transfer belt obtained from the detection unit is input, the movement speed information is read from the storage unit corresponding to the detection information, and the movement speed is set in the swing unit. It is characterized by.

  The image forming apparatus according to a third aspect is the image forming apparatus according to the second aspect, wherein the setting unit inputs detection information of an end position of the transfer belt obtained from the first detection unit, and a moving speed is stored from the storage unit. A control unit that generates and outputs an information selection signal for reading out the information, and an information selection unit that selects and outputs information on the moving speed from the storage unit based on the information selection signal output from the control unit; It is characterized by having.

  According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the third aspect, wherein the movement speed information stored in the storage unit is higher than a low-speed driving pattern that is slower than a reference movement speed and a reference movement speed. The setting unit selects the low-speed driving pattern or the high-speed driving pattern according to the detection information of the end position of the transfer belt obtained from the first detection unit. Thus, the swinging portion is set.

  The image forming apparatus according to a fifth aspect is the image forming apparatus according to the fourth aspect, wherein the setting unit is configured to perform the low-speed driving pattern or the high-speed driving according to detection information of an end position of the transfer belt obtained from the first detection unit. The oscillating unit is controlled so that the moving speed of any one of the patterns or the moving speeds of both the low-speed driving pattern and the high-speed driving pattern is slow.

  6. The image forming apparatus according to claim 6, wherein the setting unit is selected according to detection information of an end position of the transfer belt obtained from the second detection unit. Alternatively, the control range of the moving speed of the low-speed driving pattern is set wider than the moving speed of the high-speed driving pattern in the selection criterion of the high-speed driving pattern.

  An image forming apparatus according to a seventh aspect is the image forming apparatus according to the second aspect, wherein the information on the moving speed stored in the storage unit is a stepless driving pattern for controlling the moving speed steplessly, and the setting unit includes: The inclination of the graph indicating the movement speed in the width direction of the transfer belt constituting the stepless driving pattern versus the end position is set to be small.

  The image forming method according to claim 8, comprising: an endless transfer belt; a drive unit that drives the transfer belt to circulate; and a plurality of image forming units that form images of each color. An image forming apparatus that forms a color image by superimposing the image formed by the driving unit on the transfer belt that is circulated by the drive unit, while transferring the transfer belt while swinging the transfer belt in the width direction at a first moving speed. An operation for forming the color image on a belt and transferring the color image onto a predetermined sheet material is set as a normal operation mode, and the transfer belt is operated at a second movement speed that is lower than the first movement speed in the normal operation mode. The color registration adjustment mode is used to form a color misregistration correction printed image on the transfer belt while swinging the image in the width direction and read the printed image to calculate the color misregistration amount. Then, the setting of the normal operation mode or the color registration adjustment mode is input, and the transfer belt is swung in the width direction at the first moving speed according to the setting of the normal operation mode input here, The transfer belt is swung in the width direction at a second movement speed that is slower than the first movement speed in accordance with the input color registration adjustment mode setting.

  According to the image forming apparatus according to claim 1 and the image forming method according to claim 8, the image forming apparatus includes the swinging section that swings the transfer belt in the width direction corresponding to the normal operation mode or the color registration adjustment mode. The moving unit swings the transfer belt in the width direction at the first movement speed according to the setting of the normal operation mode, and the second movement speed is slower than the first movement speed according to the setting of the color registration adjustment mode. The transfer belt is swung in the width direction.

  With this configuration, the transfer belt swing period in the color registration adjustment mode can be set longer than the transfer belt swing period in the normal operation mode. Color registration adjustment mode can be implemented. Therefore, highly accurate registration correction data can be acquired, and as a result, a high-quality and high-definition color image can be formed.

  According to the image forming apparatus of the second to seventh aspects, it is possible to reduce a wobbling component that the transfer belt swings in the left-right direction (main scanning direction) with respect to the sub-conveying direction, and to a more targeted position (control target position). The transfer belt can be circulated.

1 is a conceptual diagram illustrating a configuration example of a color printer 100 as an embodiment according to the present invention. 2 is a block diagram illustrating a configuration example of a control system of the color printer 100. FIG. FIG. 6 is a graph showing an example of the relationship between the moving speed Vx in the width direction of the intermediate transfer belt 6 and the position of the roller end. It is a graph which shows the example of a relationship between the moving speed Vx of the belt width direction and belt edge part position which concern on a 1st Example. It is a graph which shows the example of a relationship between the moving speed Vx of the width direction of a belt which concerns on a 2nd Example, and a belt edge part position. It is a graph which shows the example of a relationship between the moving speed Vx of the width direction of a belt which concerns on a 3rd Example, and a belt edge part position. It is a graph which shows the example of a relationship between the moving speed Vx of the width direction of a belt which concerns on a 4th Example, and a belt edge part position. It is a graph which shows the example of a relationship between the moving speed Vx of the width direction of a belt which concerns on a 5th Example, and a belt edge part position. It is explanatory drawing which shows the example of formation of the registration mark CR for color misregistration correction, and the example of detection by two registration sensor 12A, 12B. 4 is a control flowchart showing an example of swing control of the intermediate transfer belt 6;

  Hereinafter, an image forming apparatus and an image forming method according to embodiments of the present invention will be described with reference to the drawings. A color printer 100 shown in FIG. 1 constitutes an example of a tandem type electrophotographic image forming apparatus and has an apparatus main body 101. The apparatus main body 101 includes an image forming unit 80, an intermediate transfer unit 70, a secondary transfer unit 71, a fixing device 17, and the like.

  The image forming unit 80 includes an image forming unit 10Y having a photosensitive drum 1Y (image carrier) for yellow (Y), an image forming unit 10M having a photosensitive drum 1M for magenta (M), and cyan. (C) An image forming unit 10C having a color photosensitive drum 1C and an image forming unit 10K having a black (K) color photosensitive drum 1K are provided.

  The intermediate transfer unit 70 has a belt steering control mechanism (see FIG. 2), and includes an intermediate transfer belt 6 (image carrier), primary transfer rollers 7Y, 7M, 7C, and 7K, a secondary transfer roller 72, and an upper portion. A conveyance roller 73, a lower conveyance roller 74, and a steering roller 75 are included.

  The transport roller 73 is disposed at a predetermined position above the intermediate transfer unit 70, and a steering roller 75 is disposed adjacent to the transport roller 73. The steering roller 75 swings the intermediate transfer belt 6 in the width direction of the intermediate transfer belt 6 so that the center position or the end position of the intermediate transfer belt 6 circulates a reference position that is a control target ( (See FIG. 2).

  The conveyance roller 74 is disposed at a predetermined position below the intermediate transfer unit 70, and a secondary transfer roller 72 is disposed adjacent to the conveyance roller 74. The secondary transfer roller 72 constitutes a secondary transfer unit 71. The primary transfer rollers 7Y, 7M, 7C, and 7K are interposed between the steering roller 75 and the transport roller 74, and are positioned via the intermediate transfer belt 6 at positions corresponding to the respective photosensitive drums 1Y, 1M, 1C, and 1K. Arranged.

  The intermediate transfer belt 6 is an example of an endless transfer belt, and includes a transport roller 73, a steering roller 75, primary transfer rollers 7Y, 7M, 7C, and 7K, and transport rollers 74 and 2 disposed at predetermined positions. It is supported by the next transfer roller 72 and driven so as to go around these outer sides. In this example, the intermediate transfer belt 6 is driven to rotate clockwise by a driving unit 64 shown in FIG.

  In each of the image forming units 10Y, 10M, 10C, and 10K, when the normal operation mode is set, the image forming process is performed for each of the photosensitive drums 1Y, 1M, 1C, and 1K based on the image information. The toner images of the respective colors formed by the photosensitive drums 1Y, 1M, 1C, and 1K are superimposed on the intermediate transfer belt 6 that is driven to rotate clockwise by the drive unit 64, thereby forming a color image.

  Here, the normal operation mode refers to a reference position where the center position (or end position) of the intermediate transfer belt 6 is a control target by swinging the intermediate transfer belt 6 in the width direction at the first moving speed Vx = V1. Is an operation of forming a color image on the intermediate transfer belt 6 and transferring the color image onto a predetermined sheet material (paper P).

  When the color registration adjustment mode is set, an image forming process is performed on the basis of information for forming a color misregistration correction printed image for each of the photosensitive drums 1Y, 1M, 1C, and 1K. , 1M, 1C, and 1K are formed on the intermediate transfer belt 6 that is driven to rotate clockwise by the drive unit 64.

  Here, the color registration adjustment mode means that the intermediate transfer belt 6 is swung in the width direction at a second movement speed Vx = V2, which is slower than the first movement speed Vx = V1 in the normal operation mode. A color misregistration correction mark image is formed on the intermediate transfer belt 6 so that the center position (or end position) of the belt 6 circulates a reference position that is a control target, and the color misregistration is read by reading the mark image. An operation for calculating a quantity.

  In this example, the image forming unit 10Y includes a charger 2Y, an image writing unit 3Y, a developing unit 4Y, and a cleaning unit 8Y for the image forming body in addition to the photosensitive drum 1Y, and has a yellow (Y) color. Form an image. For example, the photosensitive drum 1Y is rotatably provided near the upper right side of the intermediate transfer belt 6 and forms a Y-color toner image. In this example, the photosensitive drum 1Y is rotated counterclockwise. A charger 2Y is provided on the lower right side of the photosensitive drum 1Y, and charges the surface of the photosensitive drum 1Y to a predetermined potential.

  An image writing unit 3Y is provided almost directly beside the photosensitive drum 1Y, and a predetermined intensity based on the Y-color image data Dy is applied to the previously charged photosensitive drum 1Y. Scanning exposure is performed using the laser beam. For example, a polygon mirror type laser exposure scanning device is used for the image writing unit 3Y. An electrostatic latent image for Y color is formed on the photosensitive drum 1Y.

  A developing unit 4Y is provided above the image writing unit 3Y, and operates to develop a Y-color electrostatic latent image formed on the photosensitive drum 1Y. An image obtained by developing the electrostatic latent image with a toner agent becomes a toner image. The Y color toner image formed on the photosensitive drum 1Y is transferred to the intermediate transfer belt 6 by operating the primary transfer roller 7Y (primary transfer). A cleaning unit 8Y is provided below the left side of the photosensitive drum 1Y, and operates to remove (clean) the toner agent remaining on the photosensitive drum 1Y in the previous writing.

  In this example, an image forming unit 10M is provided below the image forming unit 10Y. The image forming unit 10M includes a photosensitive drum 1M, a charger 2M, an image writing unit 3M, a developing unit 4M, and an image forming body cleaning unit 8M, and forms a magenta (M) color image. An image forming unit 10C is provided below the image forming unit 10M. The image forming unit 10C includes a photosensitive drum 1C, a charger 2C, an image writing unit 3C, a developing unit 4C, and a cleaning unit 8C for the image forming body, and forms a cyan (C) color image.

  An image forming unit 10K is provided below the image forming unit 10C. The image forming unit 10K includes a photosensitive drum 1K, a charger 2K, an image writing unit 3K, a developing unit 4K, and a cleaning unit 8K for the image forming body, and forms a black (BK) color image. An organic photoconductor (OPC) drum is used as the photoconductor drums 1Y, 1M, 1C, and 1K. Note that the function of each member of the image forming units 10M, 10C, and 10K can be applied by replacing Y with M, C, and K for the same reference numerals of the image forming unit 10Y, and thus the description thereof is omitted.

  The color image formed on the intermediate transfer belt 6 is conveyed toward the secondary transfer unit 71 as the intermediate transfer belt 6 rotates clockwise. The secondary transfer unit 71 is disposed below the image forming unit 80 and at the lowest position of the intermediate transfer belt 6. In the normal operation mode, the secondary transfer unit 71 collectively transfers the color toner images formed on the intermediate transfer belt 6 onto the paper P (secondary transfer).

  A cleaning unit 8A is provided on the upper left side of the intermediate transfer belt 6 and operates to clean the toner agent remaining on the intermediate transfer belt 6 after the secondary transfer. A fixing device 17 is provided on the downstream side of the secondary transfer unit 71 to fix the paper P on which the color image is transferred. The recording paper after the fixing process is discharged.

  In this example, a belt sensor 11 and a resist which are described below with reference to FIG. 2 are provided below (downstream side) of the photosensitive drum 1K for BK color and at the upper right side (upstream side) of the secondary transfer unit 71. Sensors 12A and 12B are provided. The belt sensor 11 constitutes an example of a first detection unit, and the registration sensors 12A and 12B constitute an example of a second detection unit. Thus, the color printer 100 is configured.

  Next, a configuration example of the belt steering mechanism 60 of the color printer 100 and its control system will be described with reference to FIG. The color printer 100 shown in FIG. 2 has a belt steering mechanism 60. The belt steering mechanism 60 includes bearing portions 61 a and 61 b, a shaft portion 62, a connecting rod 63, a driving portion 64, and a swinging portion 65 in order to correct the deviation of the intermediate transfer belt 6.

  The steering roller 75 is configured such that one shaft end is fixed via a bearing portion 61a and the other shaft end is movable via a bearing portion 61b. The steering roller 75 has a shaft portion 62. One end of the shaft portion 62 is pivotally supported by the bearing portion 61a. The bearing portion 61a has a rotation fulcrum 601 and is attached to the apparatus main body 101 shown in FIG. The rotation fulcrum 601 is provided in a direction orthogonal to the shaft portion 62 of the steering roller 75.

  The other end of the shaft portion 62 is pivotally supported by the bearing portion 61b. The bearing 61b is movably attached to the apparatus main body 101 shown in FIG. An engagement hole 602 is provided in the bearing 61b. One end of a connecting rod 63 is connected to the engagement hole 602. A swinging portion 65 is connected to the other end of the connecting rod 63. An example of the relationship between the end position of the steering roller 75 and the moving speed Vx in the width direction of the intermediate transfer belt 6 will be described with reference to FIG.

  In FIG. 2, when the swinging portion 65 is driven and the connecting rod 63 is pushed upward, the movable-side bearing portion 61 b is displaced upward using the fixed-side bearing portion 61 a as the rotation fulcrum 601. When the bearing portion 61b is displaced upward, the steering roller 75 is displaced upward. The intermediate transfer belt 6 is shifted to the left side when the steering roller 75 is displaced upward with the bearing portion 61a as the rotation fulcrum 601. When the intermediate transfer belt 6 is shifted to the left from the center, the end of the intermediate transfer belt 6 is positioned inside.

  On the other hand, when the swinging portion 65 is driven and the connecting rod 63 is pushed downward, the bearing portion 61b is displaced downward with the bearing portion 61a serving as a rotation fulcrum 601. When the bearing portion 61b is displaced downward, the steering roller 75 is displaced downward. The intermediate transfer belt 6 is shifted (shifted) to the right side when the steering roller 75 is displaced downward with the bearing portion 61a as the rotation fulcrum 601.

  Since the intermediate transfer belt 6 is shifted from the center to the right side, the end of the intermediate transfer belt 6 is positioned outside. In the figure, HP is a home position, for example, the control position of the bearing portion 61b when the center position of the intermediate transfer belt 6 passes the center position of the steering roller 75, and the control target position “ 0 ". The moving speed Vx in the width direction of the intermediate transfer belt 6 is set as Vx = Va, Vb, V1, V2, and the like. The end position of the intermediate transfer belt 6 swings within a range of ± a and ± b with respect to the home position HP.

  The control system of the belt steering mechanism 60 of the color printer 100 shown in FIG. 2 includes the belt sensor 11, the control unit 15, the storage unit 31, the speed switching unit 59, the driving unit 64, and the swinging unit 65. The The belt sensor 11 is disposed below (downstream) the BK color photosensitive drum 1K illustrated in FIG. 1 and at the upper right (upstream) of the secondary transfer unit 71. For example, as illustrated in FIG. The end position of the intermediate transfer belt 6 is detected on the lower right side. The driving unit 64 and the swinging unit 65 are disposed at predetermined positions of the apparatus main body 101 shown in FIG.

  In this example, the control unit 15 is connected to the belt sensor 11 and the drive unit 64. The control unit 15 sets the normal operation mode or the color registration adjustment mode in the image forming unit 80 in accordance with the image forming conditions. The control unit 15 is used both as a belt steering control system and a color registration adjustment control system. Of course, the control unit 15 is not limited to the dual use, and both control systems may be controlled by separate control units 15.

  The belt sensor 11 is connected to the control unit 15. While the intermediate transfer belt 6 is running, the belt sensor 11 detects the end position of the intermediate transfer belt 6 in the width direction and generates a belt detection signal S11 (detection information). As the belt sensor 11, for example, a combination of a detection piece (lever) and an optical sensor is used. In this example, the detection piece is always in contact with the end position of the intermediate transfer belt 6, and the swinging state (projection distance) of the intermediate transfer belt 6 is detected (measured) by an optical sensor.

  A speed switching unit 59 that constitutes an example of an information selection unit is connected to the swing unit 65 described above. The storage unit 31 is connected to the speed switching unit 59. A belt detection signal S11 is output from the belt sensor 11 to the control unit 15. The control unit 15 controls the swinging unit 65 so that the position of the belt end portion becomes the target position by swinging the steering roller 75 according to the detection result of the belt sensor 11. For example, the control unit 15 inputs the belt detection signal S11 obtained from the belt sensor 11, reads the movement speed pattern data Dvi from the storage unit 31 in response to the belt detection signal S11, and sends the movement speed pattern data to the swing unit 65. Set Vx.

  In this example, the control unit 15 receives the belt detection signal S11 obtained from the belt sensor 11, generates a speed switching signal S59 (information selection signal) for reading the movement speed pattern data Dvi from the storage unit 31, and The speed switching unit 59 is controlled. The speed switching signal S59 is output from the control unit 15 to the speed switching unit 59.

  The speed switching unit 59 selects information on the moving speed Vx (hereinafter referred to as moving speed pattern data Dvi) from the storage unit 31 based on the speed switching signal S59 output from the control unit 15, and the current intermediate transfer belt 6. For example, the moving speed Vx in the main scanning direction (width direction) is switched to the target moving speed Vb. A selector is used for the speed switching unit 59. The control unit 15 and the speed switching unit 59 constitute a setting unit 50.

  The storage unit 31 stores (stores) a plurality of movement speed pattern data Dvi (i = 1 to n) for setting the movement speed Vx in the rocking unit 65. The moving speed pattern data Dvi is data for moving the intermediate transfer belt 6 in the width direction. For example, the moving speed pattern data Dv1 is data for setting the moving speed Vx of the intermediate transfer belt 6 from Va to Vb in the normal operation mode. The moving speed pattern data Dv2 is data for setting the moving speed Vx of the intermediate transfer belt 6 from Vb to Va in the color registration adjustment mode.

  A drive unit 64 is connected to the control unit 15, and the drive unit 64 drives the intermediate transfer belt 6 to circulate in the sub-scanning direction based on the belt drive signal S <b> 64. The belt drive signal S64 is output from the control unit 15 to the drive unit 64. A DC motor or a stepping motor is used for the drive unit 64. The drive unit 64 rotates the intermediate transfer belt 6 shown in FIG. 1 in the clockwise direction.

  The swing unit 65 swings the steering roller 75 up and down based on the moving speed pattern data Dvi. The moving speed pattern data Dvi is output from the speed switching unit 59 to the swing unit 65. In this example, the swinging portion 65 swings the intermediate transfer belt 6 in the width direction at the moving speed Vx = Vb according to the setting of the normal operation mode, and from the moving speed Vx = Vb according to the setting of the color registration adjustment mode. The intermediate transfer belt 6 is swung in the width direction at a slower moving speed Vx = Va. A motor, a piezoelectric actuator, or the like is used for the swing part 65.

  2 includes a color registration adjustment control system in addition to the control system of the belt steering mechanism 60. The color registration adjustment control system is configured to include image forming units 10Y, 10M, 10C, and 10K, registration sensors 12A and 12B, and a control unit 15 (shared). The control unit 15 has a correction amount calculation unit 51.

  Two registration sensors 12A and 12B are connected to the control unit 15. In the color registration adjustment mode, the registration sensors 12A and 12B detect registration marks CR formed by the photosensitive drums 1Y, 1M, 1C, and 1K for each color of YMCK and generate position detection signals S1 and S2. The position detection signal S1 is output from the registration sensor 12A to the control unit 15. The position detection signal S2 is output from the registration sensor 12B to the control unit 15. The correction amount calculation unit 51 calculates a color misregistration amount based on the position detection signals S1 and S2. Since the functions of the image forming units 10Y, 10M, 10C, and 10K have been described with reference to FIG. 1, description thereof is omitted here.

  Next, an example of the relationship between the moving speed Vx in the width direction of the intermediate transfer belt 6 and the roller end position will be described with reference to FIG. The horizontal axis shown in FIG. 3 is the roller end position, and is the end position of the steering roller 75 shown in FIG. The left direction (− direction) is the amount of displacement to the lower portion of the bearing portion 61b that supports the steering roller 75, and the right direction (+ direction) is the amount of displacement to the upper portion of the bearing portion 61b.

  The vertical axis represents the moving speed Vx of the intermediate transfer belt 6 in the width direction. The upper direction (+ direction) is the moving speed of the intermediate transfer belt 6 in the left direction, and the lower direction (− direction) is the moving speed in the right direction. The moving speed Vx is a unit of about several hundred μm per second.

  The solid line is a linear pattern I (linear function characteristic line) indicating the moving speed Vx in the belt width direction with respect to the roller end position. According to this linear pattern I, the movable bearing portion 61b of the steering roller 75 is displaced upward via the swinging portion 65 shown in FIG. 2, that is, the roller end position shown in FIG. The displacement speed Vx of the intermediate transfer belt 6 increases in the left direction.

  On the contrary, the movable bearing portion 61b of the steering roller 75 is displaced downward through the swinging portion 65 shown in FIG. 2, that is, the roller end position shown in FIG. 3 is displaced in the left direction (− direction). Then, there is a relationship in which the moving speed Vx in the right direction of the intermediate transfer belt 6 increases.

  In this example, the moving speed Vx in the width direction of the intermediate transfer belt 6 changes depending on the amount of displacement of the bearing 61b on the movable side of the steering roller 75 in the upward or downward direction. By utilizing this relationship, the steering roller 75 can be controlled to swing left and right based on the moving speed pattern data Dvi, and the intermediate transfer belt 6 can be rotated to a more targeted position (control target position).

  Next, an example of the relationship between the moving speed Vx in the belt width direction and the belt end position according to the first embodiment will be described with reference to FIG. The relationship between the moving speed Vx in the belt width direction and the belt end position shown in FIG. 4 is a data image of the moving speed pattern data Dvi. In the color printer 100 shown in FIG. 2, the moving speed pattern data Dvi stored in the storage unit 31 includes two types, that is, a low speed driving pattern and a high speed driving pattern set higher than the moving speed Vx of the low speed driving pattern. This is the case.

  In this example, by setting the moving speed pattern data Dvi in the swinging portion 65 by the speed switching portion 59, the swing cycle in the width direction of the intermediate transfer belt 6 can be set to be long. The wobbling component swaying can be reduced. Here, the swing period is, for example, that the end position of the intermediate transfer belt 6 changes from the home position HP to the outer position, returns from that position, passes through the home position HP, and changes to the inner position. Again, it means the time required for one cycle from the position to return to the home position HP.

  According to the example of the relationship between the moving speed Vx in the belt width direction and the belt end position shown in FIG. A moving speed Vx = Vb based on the driving pattern is set. In FIG. 4, the horizontal axis represents the belt end position, and the end position of the intermediate transfer belt 6 shown in FIG. The left direction (− direction) is the amount of displacement to the inside of the intermediate transfer belt 6, and the right direction (+ direction) is the amount of displacement to the outside of the intermediate transfer belt 6. The vertical axis represents the moving speed Vx in the belt width direction. The upper direction (+ direction) is the moving speed in the width direction (inner side) of the intermediate transfer belt 6, and the lower direction (− direction) is the moving speed in the width direction (outer side) of the intermediate transfer belt 6.

  In the normal operation mode, the toner adhesion amount varies depending on the color image, and is also affected by the type of paper used. Therefore, the normal operation mode is more susceptible to disturbance than in the color registration adjustment. Therefore, it is not preferable that the belt end position is away from the control target position “0” for a long time. Therefore, the control unit 15 quickly sets the belt end position to the control target position “0”. The moving portion Vx = Vb based on the high-speed drive pattern is set so as to converge, and the swinging portion 65 is controlled.

  On the other hand, in the color registration adjustment mode, since the influence of disturbance is small, even if the intermediate transfer belt 6 is separated from the control target position “0”, the belt end position may be gradually returned to the control target position “0”. . Therefore, the control unit 15 controls the swinging unit 65 by setting the moving speed Vx = Va based on the low-speed driving pattern so that the belt end position slowly converges to the control target position “0”.

  For example, in the normal operation mode, the control unit 15 controls the swing unit 65 by setting the moving speed Vx = Vb based on the high-speed drive pattern, and switches from the normal operation mode to the color registration adjustment mode. In this case, the control unit 15 switches the moving speed Vx = Vb based on the high speed driving pattern to the moving speed Va based on the low speed driving pattern regardless of the belt end position. Thus, in the color registration adjustment mode, the swinging portion 65 can be controlled by setting the moving speed Vx = Va based on the low-speed drive pattern. The-direction is similarly set and controlled.

  As described above, according to the color printer 100 according to the first embodiment, the moving speed pattern data Dvi includes two kinds of speed driving patterns and a high speed driving pattern set higher than the moving speed Vx of the low speed driving pattern. In this case, the low speed driving pattern or the high speed driving pattern is selected based on the speed switching signal S59 and set in the swinging portion 65.

  The swing unit 65 swings the intermediate transfer belt 6 in the width direction at the first moving speed Vx = Vb according to the setting of the normal operation mode. The swinging portion 65 swings the intermediate transfer belt 6 left and right in the width direction at a second moving speed Vx = Va that is slower than the first moving speed Vx = Vb according to the setting of the color registration adjustment mode. Become.

  By this oscillation, the oscillation cycle in the width direction of the intermediate transfer belt 6 can be set longer than in the normal operation mode. Therefore, the color registration adjustment can be performed with the movement speed Vx in the width direction of the intermediate transfer belt 6 kept small. A mode can be implemented. Thereby, highly accurate resist correction data can be obtained, and as a result, a high-quality and high-definition color image can be formed.

  Subsequently, an example of the relationship between the moving speed Vx in the belt width direction and the belt end position according to the second embodiment will be described with reference to FIG. In this embodiment, a case where the moving speed Vx in the width direction of the intermediate transfer belt 6 is switched in two steps depending on the belt end position of the intermediate transfer belt 6 will be described as an example. In this case, the control unit 15 creates a speed switching signal S59 according to the belt detection signal S11 obtained from the belt sensor 11, and outputs the speed switching signal S59 to the speed switching unit 59. The speed switching unit 59 selects the low speed driving pattern or the high speed driving pattern moving speed pattern data Dvi based on the speed switching signal S59 and sets it in the swinging unit 65.

  In the figure, ± a is a first belt end position indicating a reference position for switching the moving speed Vx when the control target position (target position) is “0”. Further, ± b is a second belt end position indicating a boundary position when abnormality determination is performed based on the control target position “0”. The solid line ab is the moving speed Vx = Vb as the first stage set in the control range of the belt end positions ab. The moving speed Vx = Vb constitutes a high-speed driving pattern (threshold value). The solid line 0-a is the moving speed Vx = Va as the second stage set in the control range of the belt end position 0a. The moving speed Vx = Va constitutes a low speed driving pattern (threshold value).

  In this example, when the belt end position is in the range of ± a from the control target position “0”, the moving speed Vx in the width direction of the intermediate transfer belt 6 is set to the moving speed Va based on the low speed driving pattern. When the belt end position is in the range of ± b beyond the range of ± a from the control target position “0”, the moving speed Vx in the width direction of the intermediate transfer belt 6 is set to the moving speed Vb based on the high-speed driving pattern. Is set. When the belt end position exceeds the range of ± b from the control target position “0”, the control unit 15 determines that there is some abnormality and stops the driving unit 64, the image forming unit 80, and the like. Made.

  In this embodiment, in the color registration adjustment mode, the control unit 15 moves the moving speed Vx of either the low speed driving pattern or the high speed driving pattern according to the belt detection signal S11 obtained from the belt sensor 11 or the low speed driving pattern. Further, the case where the swinging portion 65 is controlled so that the moving speed Vx of both the high-speed driving pattern and the high-speed driving pattern is slowed is given as an example.

  The moving speed Vx = Vb ′ shown in FIG. 5 is set in the range of ± b when the belt end position is in the range of ± b beyond the range of ± a in the color registration adjustment mode. This is a case where the moving speed Vx is set to be slow (Vb ′ <Vb). In the figure, the moving speed Vx = Vb ′ indicated by the two-dot chain line is set slower than the moving speed Vx = Vb.

  In this case, the moving speed Vx set in the range of ± a may be set slower. For example, the moving speed Vx = Va ′ indicated by the alternate long and short dash line in the figure is set slower than the moving speed Vx = Va.

  In the color registration adjustment mode, when the belt end position is in the range of ± a, only the moving speed Vx set in the range of ± a may be set slower (Va '<Va). Further, when the belt end position exceeds the range of ± a, the moving speed Vx in the range of ± b is set to the same setting as the moving speed Vx in the range of ± a (Va ′ = Vb ′ (Vb ′ <Va )). The-direction is similarly set and controlled.

  As described above, according to the color printer 100 according to the second embodiment, the moving speed Vx of either the low speed driving pattern or the high speed driving pattern according to the belt detection signal S11 of the intermediate transfer belt 6 or the low speed driving pattern. And the swinging part 65 is controlled so that the moving speed Vx of both the high-speed drive pattern is slow.

  By this control, as in the first embodiment, the oscillation cycle in the width direction of the intermediate transfer belt 6 can be set long, so that the color transfer speed Vx in the width direction of the intermediate transfer belt 6 can be kept small. The resist adjustment mode can be performed. Therefore, as in the first embodiment, highly accurate registration correction data can be acquired, and as a result, a high-quality and high-definition color image can be formed.

  Next, an example of the relationship between the moving speed Vx in the belt width direction and the belt end position according to the third embodiment will be described with reference to FIG. In this embodiment, the control unit 15 uses the low-speed driving pattern or the high-speed driving pattern selection reference selected according to the belt detection signal S11 of the intermediate transfer belt 6 obtained from the belt sensor 11, and the high-speed driving pattern moving speed Vx. Compared to the above, the control range of the moving speed Vx of the low speed driving pattern is set wider.

  The belt end position a 'shown in FIG. 6 is a reference position for switching the moving speed Vx set between the belt end position a and the belt end position b. The belt end position a ′ is an example in which the reference position ± a for switching the moving speed Vx in the width direction of the intermediate transfer belt 6 is changed (moved) to ± a ′ away from the control target position “0”. ing. By moving the control range ± a of the reference position to the control range ± a ′, the control range (control region) of the moving speed Vx of the low-speed drive pattern can be substantially increased. The-direction is similarly set and controlled.

  As described above, according to the color printer 100 according to the third embodiment, the control range of the moving speed Vx of the low-speed driving pattern is larger than the moving speed Vx of the high-speed driving pattern in the selection criterion of the low-speed driving pattern or the high-speed driving pattern. Since it is set widely, it is possible to obtain more accurate registration correction data, and as a result, it is possible to form a high-quality and high-definition color image.

  Next, an example of the relationship between the moving speed Vx in the belt width direction and the belt end position according to the fourth embodiment will be described with reference to FIG. In this embodiment, the moving speed pattern data Dvi stored in the storage unit 31 is a stepless drive pattern, and the control unit 15 sets the slope of the graph constituting the stepless drive pattern to be small.

  The two-dot chain line straight lines II and III shown in FIG. 7 constitute an example of a stepless drive pattern. Here, the stepless driving pattern refers to a pattern for controlling the moving speed Vx in the width direction of the intermediate transfer belt 6 steplessly. In this example, the inclination of the graph indicating the moving speed Vx in the width direction of the intermediate transfer belt 6 constituting the linear pattern III versus the belt end position is set smaller than that of the linear pattern II.

  In FIG. 7, a straight line pattern II shown by a solid line is an example in the normal operation mode, and its inclination is θ1. On the other hand, the linear pattern III is for the color resist adjustment mode, and its inclination is θ2 (θ2 <θ1). According to the linear pattern II, the moving speed Vx in the color registration adjustment mode can be set slower than in the normal operation mode by changing the inclination from θ1 to θ2 over the entire control range of the belt end region. become. Of course, the straight line pattern III may be partially changed from the inclination θ2 to the inclination θ3 (not shown) in the middle of the control range of the belt end region. The-direction is similarly set and controlled.

  As described above, according to the color printer 100 of the fourth embodiment, the graph showing the moving speed Vx in the width direction of the intermediate transfer belt 6 constituting the linear pattern III for controlling the moving speed Vx steplessly versus the position of the end portion. Since the inclination of the intermediate transfer belt 6 is set to be small, the width of the intermediate transfer belt 6 in the width direction can be set longer in the color registration adjustment mode as in the first to third embodiments. The color registration adjustment mode can be performed in a state where the moving speed Vx in the width direction 6 is kept small. Therefore, as in the first to third embodiments, highly accurate resist correction data can be acquired, and as a result, a high-quality and high-definition color image can be formed.

  Next, with reference to FIG. 8, an example of the relationship between the moving speed Vx in the belt width direction and the belt end position according to the fifth embodiment will be described. This embodiment is a modification in which the second embodiment and the third embodiment are combined. The moving speed pattern data Dvi stored in the storage unit 31 includes a reference driving pattern indicating a reference moving speed Vx, and The control unit 15 is a belt detection signal obtained from the belt sensor 11 in three cases of a low-speed drive pattern that is slower than the reference movement speed Vx and a high-speed drive pattern that is higher than the reference movement speed Vx. This is a case where a reference drive pattern, a low-speed drive pattern, or a high-speed drive pattern is selected according to S11 and set in the swing portion 65.

  In this case, the control unit 15 creates a speed switching signal S59 according to the belt detection signal S11 obtained from the belt sensor 11, and outputs the speed switching signal S59 to the speed switching unit 59. The speed switching unit 59 selects and sets the movement speed pattern data Dvi of the reference drive pattern, the low speed drive pattern, or the high speed drive pattern based on the speed switch signal S59 and sets it in the swing unit 65. By setting the moving speed pattern data Dvi in the swinging unit 65 by the speed switching unit 59, the wobbling component that causes the intermediate transfer belt 6 to swing left and right can be converged extremely finely.

  In FIG. 8, ± a is the first belt end position when the control target position (target position) is “0”. ± b is the second belt end position with reference to the control target position “0”. ± c is the third belt end position based on the control target position “0”. The solid line bc is the moving speed Vx = Vc as the first stage set in the control range of the belt end positions b to c. The moving speed Vx = Vc constitutes a high-speed driving pattern.

  The solid line ab is the moving speed Vx = Vb as the second stage set in the control range of the belt end positions ab. The moving speed Vx = Vb constitutes a reference drive pattern, for example. The solid line 0-a is the moving speed Vx = Va as the third stage set in the control range of the belt end position 0a. The moving speed Vx = Va constitutes a low speed driving pattern.

  In this example, in the normal operation mode, the control unit 15 controls the swinging unit 65 by setting the moving speed Vx = Vc based on the high-speed driving pattern, and the belt end position of the intermediate transfer belt 6 is controlled. When c reaches the belt end position b, the control unit 15 switches the movement speed Vc to the movement speed Vb based on the reference drive pattern at the belt end position b. Thereby, the moving part Vx = Vb based on a reference | standard drive pattern can be set, and the rocking | swiveling part 65 can be controlled.

  Further, when the intermediate transfer belt 6 reaches the belt end position a from the belt end position b, the control unit 15 converts the movement speed Vx = Vb at the belt end position a to the movement speed Vx = Va based on the low speed drive pattern. Switch to. The swinging portion 65 can be controlled by setting the moving speed Vx = Va based on the low speed driving pattern.

  On the other hand, in the color registration adjustment mode, since the influence of disturbance is small, even if the intermediate transfer belt 6 is separated from the control target position “0”, the belt end position may be gradually returned to the control target position “0”. . For example, in the normal operation mode, the control unit 15 controls the swing unit 65 by setting the moving speed Vx = Vc based on the high-speed drive pattern, and switches from the normal operation mode to the color registration adjustment mode. In this case, the control unit 15 switches the moving speed Vx = Vc between the belt end positions bc to the moving speed Vb based on the reference drive pattern. Thus, in the color registration adjustment mode, the swinging portion 65 can be controlled by setting the moving speed Vx = Vb based on the reference drive pattern.

  Of course, in the normal operation mode, the control unit 15 sets the moving speed Vx = Vc based on the high-speed drive pattern to control the swing unit 65, and switches from the normal operation mode to the color registration adjustment mode. In this case, the control unit 15 may switch the moving speed Vx = Vc between the belt end positions bc to the moving speed Vx = Va based on the low speed driving pattern. Thus, in the color registration adjustment mode, the swinging portion 65 can be controlled by setting the moving speed Vx = Va based on the low-speed drive pattern. The-direction is similarly set and controlled.

  As described above, in the color printer 100 according to the fifth embodiment, in the normal operation mode, the control unit 15 sets the moving speed Vx as the reference drive pattern with reference to the belt end positions a and b of the intermediate transfer belt 6. Based on the moving speed Vx = Vc based on the driving speed Vx = Va based on the low-speed driving pattern, or when switching from the normal operation mode to the color registration adjustment mode, between the belt end positions cb and between ba The moving speed Vx is switched to the moving speed Vx = Vc based on the reference driving pattern or the moving speed Vx = Va based on the low speed driving pattern.

  By this switching control of the moving speed Vx, the oscillation cycle in the width direction of the intermediate transfer belt 6 can be set longer in the color registration adjustment mode than in the normal operation mode, so the moving speed Vx in the width direction of the intermediate transfer belt 6 can be set. The color resist adjustment mode can be carried out in a state where is kept small. Thereby, highly accurate resist correction data can be obtained, and as a result, a high-quality and high-definition color image can be formed.

  In the fifth embodiment, the reference drive pattern, the low speed drive is selected based on the selection standard of the reference drive pattern, the low speed drive pattern or the high speed drive pattern selected according to the belt detection signal S11 of the intermediate transfer belt 6 obtained from the belt sensor 11. The control range of the movement speed Vx of any one of the pattern and the high-speed drive pattern may be set wider than the two control ranges of the remaining reference drive pattern, low-speed drive pattern, or high-speed drive pattern.

  Since the control range of any one of the moving speeds Vx is set wider than the two control ranges of the remaining reference drive pattern, low-speed drive pattern, or high-speed drive pattern, when the amount of deviation from the reference position is small, etc. The wobbling component that the intermediate transfer belt 6 swings to the left and right can be reduced, and the intermediate transfer belt 6 can be controlled in a very fine rotation to the control target position “0” (control target position).

  Here, an example of forming a registration mark CR for color misregistration correction and an example of detection of the registration mark CR by the two registration sensors 12A and 12B will be described with reference to FIG. The registration mark CR shown in FIG. 9 is formed on the intermediate transfer belt 6 in the color registration adjustment mode. The image forming units 10Y, 10M, 10C, and 10K are controlled so that the registration mark CR for color misregistration is formed on the intermediate transfer belt 6 by the control unit 15 shown in FIG.

  In this example, in the sub-scanning direction, which is the moving direction of the intermediate transfer belt 6, four BK-shaped registration marks CR for correcting color misregistration are formed in succession on the left and right ends. Subsequently, four C-color registration marks CR are formed continuously on the left and right ends, and four M-color registration marks CR are formed on the left and right ends. Subsequently, a Y-color registration mark CR is formed. Four marks CR are continuously formed on the left and right ends, respectively.

  Next, with reference to FIG. 10, an example of swing control of the intermediate transfer belt 6 as an embodiment will be described with respect to the image forming method according to the present invention. In this example, the moving speed pattern data Dvi is switched between the normal operation mode and the color registration adjustment mode with respect to the moving speed Vx in the width direction of the intermediate transfer belt 6 as an example.

  Regarding the moving speed Vx for moving the intermediate transfer belt 6 in the width direction, the low-speed driving pattern or the high-speed driving pattern, the reference driving pattern, the low-speed driving pattern or the high-speed driving pattern, and the linear pattern III described in the first to fifth embodiments. It is assumed that one or all of the moving speed pattern data Dvi based on the above are stored in the storage unit 31 in advance. In the image forming unit 80, the driving unit 64 is driven so as to go around the endless intermediate transfer belt 6.

  Using these as conditions for controlling the swing of the intermediate transfer belt 6, in step ST1, the control unit 15 inputs the setting of the normal operation mode or the color registration adjustment mode. The normal operation mode is set in the control unit 15 while the user operates the operation & display unit 48 to set image forming conditions in the control unit 15. The image forming conditions include paper size, number of printed sheets, paper type, basis weight, image density, and the like.

  The color registration adjustment mode can be set when maintenance is performed, when a service person operates the operation & display unit 48 to input externally to the control unit 15, when the power is turned on, when a predetermined number of sheets are printed, or when a toner agent is replenished. The case where the control unit 15 performs automatic setting is included.

  In step ST2, the control unit 15 branches the control according to the setting of the normal operation mode or the setting of the color registration adjustment mode. When the normal operation mode is set, in step ST3, the control unit 15 executes the normal operation mode while swinging the intermediate transfer belt 6 in the width direction at the first moving speed V1.

  In the normal operation mode, the toner images of the respective colors formed on the photosensitive drums 1Y, 1M, 1C, and 1K for the respective colors of YMCK are primarily transferred to the intermediate transfer belt 6, and the toner images of the respective colors are transferred to the intermediate transfer belt 6. A color image is formed by being superposed on the upper side, and is transferred onto the paper P conveyed from the paper feeding unit 20 by the secondary transfer unit 71. The sheet feeding unit 20 is disposed below the image forming unit 80. The toner image on the paper P is fixed on the paper P by the fixing device 17 and is discharged from the color printer 100.

  If the color registration adjustment mode is set, in step ST4, the control unit 15 swings the intermediate transfer belt 6 in the width direction at a second movement speed V2 that is slower than the first movement speed V1. Here, any one of the moving speed pattern data Dvi based on the low speed driving pattern or the high speed driving pattern, the reference driving pattern, the low speed driving pattern or the high speed driving pattern, the linear pattern III, or the like described in the first to fifth embodiments. Is selected to control the swinging portion 65.

  For example, the control unit 15 outputs a speed switching signal S59 to the speed switching unit 59. The speed switching unit 59 switches the movement speed pattern data Dvi from the first movement speed Vx = V1 in the normal operation mode to the second movement speed Vx = V2 (V2 <V1) based on the speed switching signal S59. The moving speed pattern data Dvi is set in the swing part 65.

  In the image forming units 10Y, 10M, 10C, and 10K for the respective colors, “F” -shaped registration marks (printed images) for color misregistration correction as shown in FIG. 9 are provided on the photosensitive drums 1Y, 1M, 1C. , 1K. The registration marks for the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are transferred to the intermediate transfer belt 6 that is circulated by the drive unit 64, and the registration marks for the respective colors are formed on the intermediate transfer belt 6.

  These registration marks for color misregistration correction are detected by the registration sensors 12A and 12B, and the amount of color misregistration with respect to the image forming position of each color registration mark is calculated. For example, the position detection signal S1 output from the registration sensor 12A is converted to analog / digital (A / D) and binarized to become position detection data. The position detection signal S2 output from the registration sensor 12B is also A / D converted and binarized to become position detection data. These position detection data are used, for example, for calculating a deviation amount of the Y, M, and C color writing positions with respect to the writing position of the BK registration mark. By calculating the shift amount, color shift amount correction data is obtained.

  In the correction amount calculation unit 51 shown in FIG. 2, a shift amount of each error factor (main scanning, overall magnification, partial horizontal magnification, skew) is calculated from the color shift correction data, and each error is calculated from the calculated shift amount. A correction amount for each factor is obtained. For example, the correction amount calculation unit 51 calculates a positional deviation amount in the main scanning direction based on the color misregistration correction data, and uses timing control data for adjusting the writing timing in the main scanning direction so as to eliminate the positional deviation amount. Generate. Based on this timing control data, the positional deviation in the main scanning direction is corrected.

  The correction amount calculation unit 51 further calculates a position shift amount in the sub-scanning direction based on the color shift correction data, and outputs timing control data for adjusting the writing timing in the sub-scan direction so as to eliminate this position shift amount. Generate. By this timing control data, the positional deviation in the sub-scanning direction is corrected.

  Further, the correction amount calculation unit 51 calculates the total lateral shift amount based on the color misregistration correction data, and generates clock control data for adjusting the frequency of the pixel clock signal so as to eliminate the entire lateral shift amount. To do. With this clock control data, the overall lateral shift amount can be corrected.

  Further, the correction amount calculation unit 51 calculates a partial lateral double shift amount based on the color misregistration correction data, and adjusts the horizontal inclination of the image writing unit 3Y and the like so as to eliminate the partial horizontal double shift amount. Write control data is generated. The partial lateral magnification shift amount can be corrected by this writing control data.

  Further, the correction amount calculation unit 51 calculates a skew shift amount based on the color shift correction data, and write control data for adjusting the vertical inclination of the image writing unit 3Y and the like so as to eliminate the skew shift amount. Generate. With this write control data, the skew deviation amount can be corrected.

  The control unit 15 controls the image forming units 10Y, 10M, 10C, and 10K so as to correct the image forming position. This control is for the image forming unit 80 to superimpose color images based on color image data with high accuracy in the normal operation mode after execution of the color registration adjustment mode.

  As described above, according to the swing control example of the intermediate transfer belt 6 according to the embodiment, the movement speed Vx in the width direction of the intermediate transfer belt 6 moves between the normal operation mode and the color registration adjustment mode. When switching the speed pattern data Dvi, the low speed drive pattern or the high speed drive pattern described in the first to fifth embodiments or the reference drive is previously stored in the storage unit 31 for the moving speed Vx for moving the intermediate transfer belt 6 in the width direction. Any one of the movement speed pattern data Dvi based on the pattern, the low speed driving pattern or the high speed driving pattern, the straight line pattern III, and the like is stored, and for example, the stored low speed driving pattern or high speed driving pattern of the first embodiment is stored. The moving speed Vx lower than the current moving speed Vx is selected from among them.

  By adopting a method of setting the moving speed Vx lower than the current moving speed Vx in the belt width direction, in the color registration adjustment mode, the oscillation cycle in the width direction of the intermediate transfer belt 6 can be set longer. The color registration adjustment mode can be performed with the moving speed Vx in the width direction of the transfer belt 6 kept small. Therefore, highly accurate registration correction data can be acquired, and as a result, a high-quality and high-definition color image can be formed.

  Note that the moving speed Vx in the belt width direction described in the first, second, and fifth embodiments is changed, and the switching position of the moving speed Vx of the intermediate transfer belt 6 described in the third embodiment is changed. It is also possible to combine them (in combination). Needless to say, the first to third and fifth embodiments may be combined with the linear pattern III described in the fourth embodiment.

  The present invention is extremely suitable when applied to a color printer, a copying machine, a multi-function machine, or the like having a belt steering control function for correcting the deviation of the intermediate transfer belt corresponding to the normal operation mode and the color registration adjustment mode. .

1Y, 1M, 1C, 1K Photosensitive drum (image forming unit)
2Y, 2M, 2C, 2K charger (image forming unit)
3Y, 3M, 3C, 3K Image writing unit (image forming unit)
4Y, 4M, 4C, 4K Development unit (image forming unit)
6 Intermediate transfer belt (transfer belt)
8A, 8Y, 8M, 8C, 8K Cleaning unit 10Y, 10M, 10C, 10K Image forming unit (image forming unit)
11 Belt sensor (first detection unit)
12A, 12A registration sensor (second detection unit)
15 Control Unit 17 Fixing Device 23 Registration Roller (Conveying Member)
31 Storage Unit 48 Operation & Display Unit 50 Setting Unit 51 Correction Amount Calculation Unit 59 Speed Switching Unit (Information Selection Unit)
64 Drive unit 65 Oscillating unit 70 Intermediate transfer unit 71 Secondary transfer unit 75 Steering roller 80 Image forming unit 100 Color printer 101 Device main unit

Claims (8)

It has an endless transfer belt, a drive unit that drives the transfer belt to circulate, and a plurality of image forming units that form images of each color, and the image formed by the image formation unit is circulated by the drive unit. An image forming unit that forms a color image by superimposing on the transfer belt;
A first detection unit for detecting an end position in the width direction of the transfer belt;
A second detection unit for detecting a color misregistration correction printed image formed on the transfer belt;
The transfer belt is swung in the width direction at a first moving speed, and the color image is formed on the transfer belt while detecting the end position in the width direction of the transfer belt by the first detection unit, The operation of transferring the color image to a predetermined sheet material is a normal operation mode,
The transfer belt is swung in the width direction at a second movement speed that is slower than the first movement speed in the normal operation mode, and the end position of the transfer belt in the width direction is determined by the first detection unit. When the color registration adjustment mode is set, an operation of forming a color misregistration correction printed image on the transfer belt while detecting and reading the printed image by the second detection unit to calculate the color misregistration amount is performed.
A setting unit for setting the normal operation mode or the color registration adjustment mode in the image forming unit;
The transfer belt is swung in the width direction at the first movement speed according to the setting of the normal operation mode, and the second movement is slower than the first movement speed according to the setting of the color registration adjustment mode. An image forming apparatus comprising: a swinging unit configured to swing the transfer belt in the width direction at a speed. A storage unit storing information on a plurality of moving speeds for setting a moving speed in the swing unit;
The setting unit
The detection information of the end position of the transfer belt obtained from the first detection unit is input, the information on the movement speed is read from the storage unit corresponding to the detection information, and the movement speed is set to the swing unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is set. The setting unit
A control unit that inputs detection information of the end position of the transfer belt obtained from the first detection unit, generates and outputs an information selection signal for reading out information on the moving speed from the storage unit, and
The image forming apparatus according to claim 2, further comprising: an information selection unit that selects and outputs information on a moving speed from the storage unit based on an information selection signal output from the control unit. The information on the moving speed stored in the storage unit is two types, a low-speed driving pattern that is slower than a reference moving speed and a high-speed driving pattern that is higher than a reference moving speed,
The setting unit
4. The low-speed drive pattern or the high-speed drive pattern is selected according to detection information of the end position of the transfer belt obtained from the first detection unit and set to the swinging unit. The image forming apparatus described. The setting unit
The moving speed of either the low-speed driving pattern or the high-speed driving pattern or both the low-speed driving pattern and the high-speed driving pattern according to the detection information of the end position of the transfer belt obtained from the first detection unit The image forming apparatus according to claim 4, wherein the swinging unit is controlled such that the moving speed of the image forming unit decreases. The setting unit
The low-speed drive pattern or the high-speed drive pattern selection criterion selected according to the detection information of the end position of the transfer belt obtained from the second detection unit is lower than the moving speed of the high-speed drive pattern. The image forming apparatus according to claim 5, wherein a control range of a moving speed of the drive pattern is set wide. The movement speed information stored in the storage unit is a stepless driving pattern for controlling the movement speed steplessly,
The setting unit
The image forming apparatus according to claim 2, wherein an inclination of a graph indicating a moving speed in the width direction of the transfer belt constituting the stepless drive pattern versus an end position is set to be small. It has an endless transfer belt, a drive unit that drives the transfer belt to circulate, and a plurality of image forming units that form images of each color, and the image formed by the image formation unit is circulated by the drive unit. An image forming apparatus for forming a color image by superimposing on the transfer belt,
The operation of forming the color image on the transfer belt while swinging the transfer belt in the width direction at a first moving speed, and transferring the color image to a predetermined sheet material is a normal operation mode.
While the transfer belt is swung in the width direction at a second movement speed slower than the first movement speed in the normal operation mode, a color misregistration correction mark image is formed on the transfer belt, and the mark image is When the color registration adjustment mode is set to read and calculate the amount of color misregistration,
Input settings for the normal operation mode or color registration adjustment mode,
The transfer belt is swung in the width direction at the first moving speed according to the input setting of the normal operation mode,
An image forming method, wherein the transfer belt is swung in the width direction at a second moving speed that is slower than the first moving speed in accordance with the input color registration adjustment mode setting.

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