JP2009151185A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of highly precisely keeping a belt into a stable state less in eccentricity with few processing burdens. <P>SOLUTION: The image forming apparatus includes: a detecting section that detects the widthwise position of the rotating endless belt; a moving section that moves the belt 21 widthwise; and a control section that controls the operation of the moving section based on the detection result of the detecting section so that skew of the belt 21 is corrected. The control section alters the content of the control of the skew correction if there is any change in an external factor (e.g., firm press against another member or release from firm press, or start of the drive of the belt) relative to the belt. For example, until the belt stabilizes after a change in external factor, a control period is made shorter than that for a normal period, or the correction to the eccentricity is increased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including an endless rotating belt, and more particularly to an image forming apparatus that corrects a deviation of a belt.

  In the image forming apparatus, a wide and endless belt that circulates is used as an image carrier and a pressing means for transferring and fixing. For example, in an image forming apparatus such as a tandem type color copying machine using an electrophotographic process, a photosensitive drum, a charging drum is charged for each of yellow (Y), magenta (M), cyan (C), and black (K) colors. An image forming unit comprising a scanning device, a scanning optical device, a developing device, etc. is prepared, arranged along an endless intermediate transfer belt, and images of each color Y, M, C, K are superimposed on the circulating intermediate transfer belt Together, a color image is formed.

  When such a meandering or deviation occurs in the belt, a color shift occurs and the image quality deteriorates. Therefore, in order to make the belt run stably, control is performed to periodically detect and correct the deviation state of the belt with a sensor. Also, immediately after returning from troubles such as belt replacement work, maintenance, or jam processing, there is a possibility that the deviation of the belt is larger than that in the normal copying operation. Therefore, the meandering correction table is switched according to the operating state of the device (normal copy operation or operation after recovery from trouble, etc.). There is an apparatus in which a correction amount is increased to perform a quick correction (see, for example, Patent Document 1).

JP-A-9-48533

  In order to maintain a stable running state without deviation with high accuracy, it is preferable to detect and correct the belt deviation state in a short cycle. The burden will increase.

  In the method disclosed in Patent Document 1 for switching the meandering correction table depending on whether the copying operation or the trouble is restored, the same control is performed based on the same meandering correction table in the same operation state. For this reason, in order to obtain a stable running state with little deviation in the copying operation, highly accurate control is always performed during the copying operation, which increases the processing load on the system.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can accurately maintain a belt in a stable running state with little deviation with a small processing load.

  The gist of the present invention for achieving the object lies in the inventions of the following items.

[1] A belt that is laid to form a circuit path;
A drive unit for circling the belt;
A detection unit for detecting a position in the width direction of the belt;
A moving part for moving the belt in the width direction;
A control unit that controls the operation of the moving unit based on the detection result of the detection unit so that the deviation of the belt is corrected,
The control unit changes the content of the control when there is a change in an external factor with respect to the belt.

  In the above invention, when the control unit controls the operation of the moving unit based on the detection result of the detection unit so that the deviation of the belt is corrected, there is a change in external factors with respect to the belt. Change to

[2] A crimping / releasing part that switches between a state in which the belt and another member are crimped and a state in which the crimping is released is provided,
The image forming apparatus according to [1], wherein the change in the external factor is the switching.

  In the above-described invention, there is a possibility that the stable running of the belt may be hindered by the crimping / releasing, and therefore the control unit changes the control content by the occurrence of the event.

[3] The image forming apparatus according to [1], wherein the change in the external factor is a start of driving of the belt.

  In the above invention, since the belt travel is assumed to be unstable for a while after the start of driving the belt, the control unit changes the control content during that time.

[4] The image forming apparatus according to [1], wherein the change in the content of the control is a change in a control amount of the moving unit with respect to a deviation amount of the belt.

  In the above invention, for example, the control unit increases the control amount with respect to the deviation amount of the belt after the change of the external factor occurs compared to before that. Thereby, the deviation of the belt can be corrected quickly.

[5] The image forming apparatus according to [1], wherein the change in the content of the control is a change in a detection cycle by the detection unit.

  In the above invention, for example, the control unit shortens the detection cycle of the belt position after the change of the external factor compared to before that. The detection cycle in normal time can be lengthened and the processing load is reduced.

[6] The control unit returns the content of the control to the content before the change when a predetermined time has elapsed after changing the content of the control based on a change in the external factor. 1].

  In the above invention, the control unit determines that the running of the belt is stable when a predetermined time has elapsed, and returns the control content to before the change.

[7] The image forming apparatus according to [6], further including a changing unit that changes a set value for the predetermined time.

  In the above-described invention, for example, the predetermined time can be changed in accordance with the belt deterioration or individual differences.

[8] After the control unit has changed the content of the control due to the occurrence of the external factor, the control unit determines whether or not the belt travel is stable based on the detection result of the detection unit. The image forming apparatus according to [1], wherein when the determination is made, the content of the control is returned to the content before the change.

  In the above invention, the control unit determines whether or not the belt travel is stable based on the detection result of the detection unit.

[9] The image forming apparatus according to [8], further including a determination reference changing unit that changes a reference value of the determination.

  In the above-described invention, for example, the determination reference value can be changed in accordance with belt degradation, individual differences, and the like.

[10] The image formation according to any one of [1] to [9], wherein the belt is a belt on which an image is formed or abutted against a transfer paper on which an image is formed. apparatus.

  According to the image forming apparatus of the present invention, the belt can be accurately maintained in a stable running state with little deviation with a small processing load.

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

  FIG. 1 shows a cross-sectional configuration of an image forming apparatus 10 according to an embodiment of the present invention, and FIG. 2 shows an electrical schematic configuration of the image forming apparatus 10. The image forming apparatus 10 is an apparatus called a color digital copying machine, and includes a reading unit 12 having an automatic document feeder 11, a display operation unit 13, a control unit 14, and a printer unit 20. .

  The automatic document feeder 11 (see FIG. 1) has a function of feeding the originals 2 stacked on the original placement tray 11a one by one to the reading portion of the reading unit 12, and discharging the read originals to the discharge tray 11b. Fulfill.

  The reading unit 12 has a function of reading a document in color. The reading unit 12 includes an exposure scanning unit 15 including a light source and a mirror, a color line image sensor 16 that receives reflected light from the document and outputs an electrical signal corresponding to the light intensity, and reflection from the document. Various mirrors 17 and a condenser lens 18 for guiding light to the line image sensor 16 are provided.

  The printer unit 20 is a tandem type image forming apparatus, and includes an intermediate transfer belt 21 that is wider and endless than transfer paper, and a plurality of image forming units 30Y that form single-color images on the intermediate transfer belt 21, respectively. , 30M, 30C, and 30K, a paper feed unit 22 that feeds transfer paper, a transport unit 23 that transports the fed transfer paper, and a fixing device 24.

  The image forming unit 30Y forms a yellow (Y) image on the intermediate transfer belt 21, the image forming unit 30M forms a magenta (M) image on the intermediate transfer belt 21, and the image forming unit 30C uses cyan. (C) A color image is formed on the intermediate transfer belt 21, and the image forming unit 30 K forms a black (K) color image on the intermediate transfer belt 21.

  The image forming unit 30Y includes a photosensitive member 31Y as a cylindrical electrostatic latent image carrier on which an electrostatic latent image is formed, a charging device 32Y, a developing device 33Y, and a cleaning device 34Y disposed around the photosensitive member 31Y. Have In addition, a writing unit 35 </ b> Y including a laser diode that is turned on / off according to image data, a polygon mirror, various lenses, a mirror, and the like is provided.

  The photoreceptor 31Y is driven by a drive unit (not shown) and rotates in a certain direction (the direction of arrow A in the figure), and the charging device 32Y uniformly charges the photoreceptor 31Y. The writing unit 35Y functions to repeatedly scan the surface of the cylindrical photoreceptor 31Y with the laser light in the axial direction (main scanning direction) by reflecting the laser light emitted from the laser diode with a rotating polygon mirror. An electrostatic latent image is formed on the photoreceptor 31Y by scanning the uniformly charged surface of the photoreceptor 31Y with a laser beam that is turned on / off according to yellow image data.

  The developing device 33Y visualizes the electrostatic latent image on the photoreceptor 31Y with yellow toner. The toner image formed on the surface of the photoreceptor 31 </ b> Y is transferred to the intermediate transfer belt 21 at a location where it contacts the intermediate transfer belt 21. The cleaning device 34Y functions to remove and collect the toner remaining on the surface of the photoreceptor 31Y after the transfer by rubbing with a blade or the like.

  The image forming unit 30M, the image forming unit 30C, and the image forming unit 30K are different from the image forming unit 30Y except that the toner colors are different and the laser light is turned on / off with image data corresponding to each color. The configuration is the same, and a description thereof is omitted. In the figure, elements having the same configuration but having different colors are denoted by the same numerals and subscripts of “M”, “C”, and “K” instead of “Y”.

  The intermediate transfer belt 21 is wound around a plurality of rollers so as to form a circulation path, and rotates in the direction of arrow B in the drawing during image formation. In the process of turning, the images (toner images) of the respective colors (Y), (M), (C), and (K) are overlaid on the intermediate transfer belt 21 by the image forming units 30Y, 30M, 30C, and 30K. A color image is synthesized by being formed. This color image is transferred from the intermediate transfer belt 21 to the transfer paper by applying a high pressure to the secondary transfer roller 25 at the secondary transfer position D. A belt cleaning device 26 for removing the toner remaining on the intermediate transfer belt 21 after the transfer is installed downstream of the secondary transfer position D in the circumferential direction.

  The paper feed unit 22 has a plurality of paper feed cassettes 22a for storing transfer papers to be used for printing, and fulfills a function of feeding transfer sheets from the selected paper feed cassettes 22a one by one toward the transport unit 23. . The transport unit 23 passes the secondary transfer position D and the fixing device 24 through the secondary transfer position D and the fixing device 24 to discharge the transfer paper fed from the paper feed cassette 22a to the paper discharge tray outside the apparatus, and the fixing device 24. A reverse path 23b that reverses the front and back of the passed transfer paper and then merges again with the normal path 23a upstream of the secondary transfer position D is provided, which supports double-sided printing.

  The printer unit 20 primarily transfers each color image formed on the photoconductors 31Y, 31M, 31C, and 31K to the intermediate transfer belt 21 in accordance with the image data, and is formed on the intermediate transfer belt 21 in an overlapping manner. Is subjected to secondary transfer onto a transfer sheet by applying a high pressure to the secondary transfer roller 25, and the transfer sheet is fixed by a fixing device 24 and output.

  The control unit 14 functions to control the entire operation of the image forming apparatus 10. The CPU (Central Processing Unit), a program executed by the CPU, a ROM (Read Only Memory) in which various fixed data are stored, and the CPU The main part is a RAM (Random Access Memory) or the like which is a work area when executing.

  As shown in FIG. 2, the reading unit 12, the display operation unit 13, the image processing unit 50, the nonvolatile memory 51, and the printer unit 20 are connected to the control unit 14. The display operation unit 13 has a function of receiving various operations and settings from the user and a function of displaying various operation screens, setting screens, guidance screens, and the like to the user. The display operation unit 13 includes, for example, a liquid crystal display having a touch panel for detecting a pressed position on the surface and other switches.

  The image processing unit 50 performs various types of image processing on the image data of each color input from the line image sensor 16 of the reading unit 12, compresses and temporarily stores the data, and then decompresses the data (Y). , (M), (C), and (K) functions to output the image data of each color to the image forming units 30Y, 30M, 30C, and 30K of the printer unit 20, and the like. The nonvolatile memory 51 is a memory that retains stored contents even when the power is turned off, and stores various setting values.

  The control unit 14 further includes a belt drive motor 52 as a drive unit for rotating the intermediate transfer belt 21, a deviation sensor 53 as a detection unit for detecting the position in the width direction of the intermediate transfer belt 21, and the width of the intermediate transfer belt 21. A stepping motor 54 serving as a power source for the moving unit that moves in the direction, and a crimping / releasing unit that switches between a state in which the intermediate transfer belt 21 is crimped to the photoreceptors 31Y, 31M, 31C, and 31K and a state in which the crimping is released and separated. 55 etc. are connected. The crimping / releasing unit 55 performs crimping and releasing with the motor as power. The controller 14 controls the displacement of the intermediate transfer belt 21 by controlling the operation of the stepping motor 54 of the moving unit based on the detection result of the displacement sensor 53 so that the meandering and displacement of the intermediate transfer belt 21 are corrected. Execute.

  In addition, the control unit 14 is connected to sensors, drive motors, and the like related to the paper feeding unit 22, the conveyance unit 23, the fixing device 24, and the like, and these are controlled by the control unit 14.

  FIG. 3 schematically shows the drive mechanism of the intermediate transfer belt 21. The intermediate transfer belt 21 is looped around a plurality of cylindrical rollers (see FIG. 1). Of the plurality of rollers, the driving roller 61 is rotationally driven by the belt driving motor 52, and the other rollers do not have a driving source.

  The moving unit that moves the intermediate transfer belt 21 in the width direction includes an adjustment roller 62 and a movable bearing unit 63. The adjustment roller 62 is attached so that the inclination of the shaft can be changed around its one end 62a, and the other end 62b of the adjustment roller 62 is pivotally supported by a movable bearing portion 63 including a gear and a stepping motor 54. ing. By rotating the stepping motor 54 forward or backward, the angle of the shaft of the adjustment roller 62 can be adjusted within a predetermined range of ± with respect to the state parallel to the shaft of the drive roller 61.

  The controller 14 recognizes the position of the intermediate transfer belt 21 in the width direction by the offset sensor 53. For example, when the intermediate transfer belt 21 is shifted in the offset direction J as shown in FIG. The deviation of the intermediate transfer belt 21 is corrected by changing the inclination of the adjustment roller 62 by the correction amount Q so as to move in the direction K (belt movement direction) opposite to the deviation direction J. In this manner, controlling the inclination of the adjustment roller 62 (operation of the stepping motor 54) based on the detection result of the deviation sensor 53 so that the deviation of the intermediate transfer belt 21 is corrected is hereinafter referred to as steering control. Call.

  The deviation sensor 53 includes a first sensor 53a, a second sensor 53b, and a third sensor 53c that are arranged at predetermined intervals in the width direction of the intermediate transfer belt 21. As shown in FIG. 5, irregularities are formed on the back surface of the intermediate transfer belt 21, and the deviation sensors 53 a, 53 b, and 53 c are detected from the intermediate transfer belt 21 at the detection positions (dotted line positions in FIG. 5). Alternatively, when facing the concave portion 65, it is turned off (OFF), and when facing the convex portion 66, it is turned on (ON).

  FIG. 5 shows the positional relationship between the intermediate transfer belt 21 and the displacement sensors 53a, 55b, and 55c separately from the first state to the sixth state, and FIG. 6 shows the first state to the sixth state in FIG. An example of the control table 70 showing the on / off states of the deviation sensors 53a, 53b, 53c, the normal steering control correction amount, and the non-normal steering control correction amount is shown. The correction amount (control amount for the moving unit) is represented by the rotation direction of the stepping motor 54 (forward rotation: CW, reverse rotation: CCW) and the number of steps. The control unit 14 changes the content of the steering control between the normal time and the non-normal time.

  The normal time is a period in which the steering control is performed on the assumption that the traveling state of the intermediate transfer belt 21 (particularly, the offset state during traveling) is stable. The non-normal time is a period for performing the steering control on the assumption that the running state of the intermediate transfer belt 21 is not stable. The non-normal time is a period other than the normal time.

  Specifically, the control unit 14 affects the intermediate transfer belt 21 due to the occurrence of the change of the external factor after the change of the predetermined external factor occurs (unstable). The period until it is determined that the driving state has been resolved is recognized as an abnormal time. An external factor is an event other than changing the angle of the adjustment roller 62 by the stepping motor 54 among the events of applying force to the intermediate transfer belt 21. The change in the external factor means a change in the force applied to the intermediate transfer belt 21 by the above event. Any one or more of the changes in the external factors is selected as a change in the external factors (changes in the external factors to be controlled) that cause the control unit 14 to change the contents of the steering control. It is.

  Here, the control unit 14 steers the change from the released state to the pressed state by the crimping / release unit 55, the change from the crimped state to the released state, and the start of driving of the intermediate transfer belt 21 by the belt drive motor 52. It is chosen to change external factors that cause changes in control content. In addition, changes in external factors to be controlled may include external impacts and vibrations, and increase / decrease in the driving speed of the intermediate transfer belt 21 by the belt drive motor 52.

  The first state in FIG. 5 is a state in which the intermediate transfer belt 21 is shifted (moved) from the center position to the rear side of the machine (G in the drawing) beyond an allowable amount, and the sixth state is a state in which the intermediate transfer belt 21 is centered. This is a state in which it has shifted (moved) from the position to the front side of the machine (H in the figure) exceeding the allowable amount. In the first state or the sixth state, the third sensor 53c is turned on. At this time, the control unit 14 determines that the deviation of the intermediate transfer belt 21 is abnormally large, and performs predetermined error processing such as emergency stop. Do.

  The third state is a state in which the intermediate transfer belt 21 is at a position slightly moved from the center position to the machine rear side G, the first sensor 53a and the third sensor 53c are turned off, and the second sensor 53b is turned on. The second state is a state in which the intermediate transfer belt 21 is between the first state and the third state, and the first sensor 53a, the second sensor 53b, and the third sensor 53c are all turned off.

  The fourth state is a state in which the intermediate transfer belt 21 is moved to the machine front side H slightly from the center position, and the first sensor 53a and the second sensor 53b are turned on, and the third sensor 53c is turned off. The fifth state is a state in which the intermediate transfer belt 21 is intermediate between the fourth state and the sixth state, the first sensor 53a is turned on, and the second sensor 53b and the third sensor 53c are turned off.

  Here, as shown in FIG. 6, in the normal state, the correction amount in the second state is 20 steps in the CW direction, the correction amount in the third state is 10 steps in the CW direction, and the correction amount in the fourth state is CCW. The correction amount in the fourth state is set to 20 steps in the CCW direction. In a non-normal time, the correction amount in the second state is 25 steps in the CW direction, the correction amount in the third state is 15 steps in the CW direction, the correction amount in the fourth state is 15 steps in the CCW direction, and the fourth state. The correction amount is set to 25 steps in the CCW direction.

  That is, when the amount of deviation in the width direction of the intermediate transfer belt 21 is the same, the correction amount in the non-normal time is made larger than the correction amount in the normal time. Further, the larger the deviation amount from the center position, the larger the correction amount.

  The control unit 14 reads from the control table 70 the normal correction amount corresponding to the position in the width direction of the intermediate transfer belt 21 (from the first state to the sixth state) detected by the deviation sensor 53 in the normal state. Then, the stepping motor 54 is operated in accordance with the normal correction amount to change the angle of the adjustment roller 62. On the other hand, in the non-normal time, the correction amount in the non-normal time corresponding to the position in the width direction of the intermediate transfer belt 21 (first state to sixth state) detected by the deviation sensor 53 is read from the control table 70. The angle of the adjustment roller 62 is changed by operating the stepping motor 54 according to the non-normal correction amount. Each correction amount registered in the control table 70 can be arbitrarily changed by a user or a service person through a predetermined setting change screen displayed on the display operation unit 13.

  Next, control of the intermediate transfer belt 21 during image formation will be described. FIG. 7 shows the overall flow of the control. When image formation is performed, the control unit 14 first starts rotation (circulation) of the intermediate transfer belt 21 (step S101) and also starts steering control (step S102), and rotates the intermediate transfer belt 21 (running). Wait until the state becomes stable (step S103; No). When the rotation state of the intermediate transfer belt 21 is stabilized (step S103; Yes), the control unit 14 operates the pressure bonding / release unit 55 to perform pressure bonding between the intermediate transfer belt 21 and the photoreceptors 31Y, 31M, 31C, and 31K ( Step S104), and then image formation for the designated number of prints is performed. That is, a transfer sheet is fed, images of the respective colors are formed on the photoreceptors 31Y, 31M, 31C, and 31K according to the image data, and these images are primarily transferred onto the intermediate transfer belt 21 and superimposed, The superimposed image is subjected to secondary transfer from the intermediate transfer belt 21 to the transfer paper by applying a high pressure to the secondary transfer roller 25, and the transfer paper is fixed by the fixing device 24 and output to form an image. .

  When the image forming for the designated number of printed sheets is completed (step S105; Yes), the control unit 14 controls the crimping / release unit 55 to release the crimping (step S106), and then rotates the intermediate transfer belt 21. Stop (step S107), end the steering control (step S108), and end the process (end).

  Next, the flow of steering control performed by the control unit 14 will be described.

  The control unit 14 changes the content of the steering control between the normal time and the non-normal time. Specifically, the control content is changed so that the processing load of the control unit 14 at the normal time is reduced as compared with the non-normal time. Alternatively, the control content is changed so that the offset correction in the non-normal time can be performed more quickly than in the normal time. Here, in addition to changing the correction amount described above, the detection cycle by the deviation sensor 53 is switched between normal time and non-normal time. Hereinafter, two types of steering control with different determination methods for normal time and non-normal time will be described.

  FIG. 8 shows the flow of steering control when the period from the occurrence of the change in the external factor until the predetermined time elapses is set to the non-normal time. The control unit 14 checks whether or not a change in an external factor has occurred (step S201), and if not (step S201; No), performs a normal steering control. That is, the next detection by the deviation sensor 53 is set after 500 ms (milliseconds) (step S205), and the set time is awaited (step S206; No). When the set time (500 ms) elapses and the sensor check time comes (step S206; Yes), the detection values of the offset sensors 53a, 53b, 53c are taken in, the detection results (on / off) and the control table 70 are detected. The position of the intermediate transfer belt 21 in the width direction (from the first state to the sixth state) is recognized and the normal correction amount corresponding to the position is read from the control table 70, and the correction amount is compared. Accordingly, the stepping motor 54 is operated to correct the deviation (step S207), and the process returns to step S201.

  If a change in the external factor has occurred (step S201; Yes), it is checked whether or not a predetermined time has elapsed since the occurrence of the change in the external factor (step S202). The set value for the predetermined time is stored in the non-volatile memory 51, and the user or service person can arbitrarily set and change the value by operating the display operation unit 13 as a changing unit.

  When the predetermined time has elapsed since the occurrence of the change in the external factor (step S202; Yes), the normal steering control is performed. That is, the next detection by the deviation sensor 53 is set after 500 ms (step S203), and the set time is awaited (step S206; No). When the set time (500 ms) has elapsed and the sensor check time has arrived (step S206; Yes), the detection values of the offset sensors 53a, 53b, 53c are taken in, and the detection results (on / off) and registration of the control table 70 are performed. The position in the width direction of the intermediate transfer belt 21 (from the first state to the sixth state) is recognized in comparison with the contents, and a normal correction amount corresponding to the position is read from the control table 70, and according to the correction amount. The stepping motor 54 is operated to correct the deviation (step S207), and the process returns to step S201.

  When the predetermined time has not elapsed since the occurrence of the change in the external factor (step S202; No), the steering control in the non-normal time is performed. That is, the next detection by the deviation sensor 53 is set after 100 ms, which is shorter than the normal time (step S204), and the passage of the set time is awaited (step S206; No). When the set time (100 ms) has elapsed and the sensor check time has come (step S206; Yes), the detection values of the offset sensors 53a, 53b, 53c are taken in, the detection results (on / off) and the control table 70 are taken. The position of the intermediate transfer belt 21 in the width direction (from the first state to the sixth state) is recognized in comparison with the registered contents of the image, and the non-normal correction amount corresponding to the position is read from the control table 70, and the correction is performed. The stepping motor 54 is operated according to the amount to correct the deviation (step S207), and the process returns to step S201.

  As described above, the steering control is executed in a short period (100 ms in this example) only in the non-normal time when it is assumed that the running of the intermediate transfer belt 21 becomes unstable due to the occurrence of a change in external factors, and the intermediate transfer belt 21. Since the steering control is executed in a longer cycle (500 ms in this example) than in the normal time when it is assumed that the running of the vehicle is stable, control is performed compared to the case where the steering control is always performed in the non-normal time cycle. The processing burden on the unit 14 is reduced. Further, in the non-normal steering control, the correction amount is set larger than that in the normal time, so that the deviation of the intermediate transfer belt 21 can be corrected quickly.

  Since the change in the external factor is caused by the control of the crimping / releasing unit 55 by the control unit 14 or the control of the belt drive motor 52, the control unit 14 can recognize the occurrence time of the external factor in advance. it can. Therefore, it may be configured to execute the non-normal steering control by immediately proceeding to step S207 at the time when the change of the external factor occurs even while waiting for the elapse of the predetermined time in step S206. . For example, the control unit 14 skips the processing of FIG. 8 to step S207 at the time of switching between the crimping / releasing state by the crimping / releasing unit 55 or starting the driving of the belt drive motor 52, and the correction amount for the non-normal time Execute steering control with As described above, if the steering control is performed with the non-normal control contents at the time of occurrence of the external factor or immediately after the occurrence, even if the detection cycle in the normal steering control is set to a relatively long time, the external control is not performed. Steering control can be performed in quick response to the occurrence of a change in the mechanical factor.

  FIG. 9 shows the flow of steering control when it is determined from the detection results of the deviation sensors 53a, 53b, and 53c whether the running of the intermediate transfer belt 21 is in a stable state and the end of the abnormal time is recognized. . Here, predetermined state information indicating whether or not the running of the intermediate transfer belt 21 is in a stable state is stored in a memory, and the control unit 14 sets the state information to “non-display” when a change in an external factor occurs. After that, the state information is returned to the “stable state” when it is determined from the detection results of the deviation sensors 53a, 53b, and 53c that the running state of the intermediate transfer belt 21 is stable. For example, it is determined that the intermediate transfer belt 21 has returned to the stable state when the change in the position in the width direction of the intermediate transfer belt 21 is within a predetermined reference time and below a specified amount. The reference value (reference time or specified amount) for this determination is stored in the nonvolatile memory 51, and the user or serviceman can arbitrarily change the setting through the display operation unit 13 as a determination reference changing unit. Yes. Whether or not the state information is to be returned to the “stable state” is determined based on the position in the width direction of the intermediate transfer belt 21 recognized in step S215 described later.

  The controller 14 refers to the state information described above to determine whether or not the running of the intermediate transfer belt 21 is in a stable state (step S211). When it is in a stable state (step S211; Yes), steering control at normal time is performed. That is, the next detection by the deviation sensor 53 is set after 500 ms (step S212), and the set time is awaited (step S214; No). When the set time (500 ms) has elapsed and the sensor check time has arrived (step S214; Yes), the detection values of the offset sensors 53a, 53b, 53c are taken in, the detection results (on / off), and the control table 70 The position of the intermediate transfer belt 21 in the width direction (from the first state to the sixth state) is recognized and the normal correction amount corresponding to the position is read from the control table 70, and the correction amount is compared. Accordingly, the stepping motor 54 is operated to correct the deviation (step S215), and the process returns to step S211.

  When the running of the intermediate transfer belt 21 is not in a stable state (step S211; No), the control unit 14 performs steering control in an abnormal state. That is, the next detection by the deviation sensor 53 is set after 100 ms, which is shorter than the normal time (step S213), and the elapse of the set time is awaited (step S214; No). When the set time (100 ms) has elapsed and the sensor check time has arrived (step S214; Yes), the detection values of the offset sensors 53a, 53b, 53c are taken in, the detection results (on / off), and the control table 70. The position of the intermediate transfer belt 21 in the width direction (from the first state to the sixth state) is recognized in comparison with the registered contents of the image, and the non-normal correction amount corresponding to the position is read from the control table 70, and the correction is performed. The stepping motor 54 is operated according to the amount to correct the deviation (step S215), and the process returns to step S211.

  In the process shown in FIG. 9 as well, in the same way as in the process of FIG. 8, it is possible to obtain effects such as reduction of the processing load on the control unit 14 and quick correction for occurrence of a change in external factors. it can. In the process of FIG. 9, since it is determined whether or not the running of the intermediate transfer belt 21 is actually in a stable state from the detection result of the deviation sensor 53, it is surely recognized that the intermediate state is in a stable state. The end of normal time can be determined. On the other hand, in the process of FIG. 8, the non-normal time control content is restored from the non-normal control content when a predetermined time has elapsed since the occurrence of the change in the external factor, so that it is easy to determine the non-normal time end time. Thus, the processing burden on the control unit 14 is reduced. Note that the predetermined time may be changed according to the type of external factor.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention can be changed or added without departing from the scope of the present invention. include.

  In the embodiment, the normal detection cycle is set to 500 ms, and the non-normal detection cycle is set to 100 ms. However, if there is a relationship between the non-normal detection cycle <the normal detection cycle, each is set to an arbitrary time. be able to. Further, the detection cycle of the steering control at the normal time and the non-normal time may be stored in the nonvolatile memory 51 so that the user or serviceman can arbitrarily change the setting through the display operation unit 13 or the like. .

  In addition, the method of detecting the position in the width direction of the intermediate transfer belt 21 and the configuration of the moving unit that moves the intermediate transfer belt 21 in the width direction are not limited to those exemplified in the embodiment, and perform the same functions. Any configuration can be used. For example, the arrangement and type of the deviation sensor 53 may be changed as appropriate.

  Further, when an external factor such as an external impact that is not under the control of the control unit 14 is used as an external factor that causes the switching of the steering control, a sensor that detects the occurrence of a change in the external factor, for example, A vibration sensor or the like may be provided separately.

  In the embodiment, the case where the intermediate transfer belt 21 is a control target has been described, but other types of belts may be used as long as the belt is subjected to steering control that corrects meandering and deviation. For example, in addition to the belt on which the image is formed on the surface like the intermediate transfer belt 21, a belt that is in contact with or pressed against the transfer paper in a part of the circulation path may be used.

  More specifically, when transferring the color image formed on the intermediate transfer belt 21 to the transfer paper, the endless belt (secondary transfer belt) that circulates the role of pressing the transfer paper from the back toward the intermediate transfer belt 21. ), The secondary transfer belt may be a control target. In the case of the secondary transfer belt, an external factor is a change in the operation of pressing and releasing the secondary transfer belt on the intermediate transfer belt 21. Further, in the process of fixing the toner image by pressurizing and heating the transfer paper, when the transfer paper is pressed with a rotating wide endless fixing belt, the fixing belt may be controlled. In the case of the fixing belt, for example, the pressing and releasing of the fixing belt to / from the opposite roller, heating on / off, and the like are external factors.

  In the embodiment, the control unit 14 performs all control, but a plurality of control units may perform distributed control. In addition, the image forming apparatus 10 is not limited to a multifunction machine, and may be an apparatus having a function of forming an image on transfer paper, such as a printer or a facsimile.

1 is an explanatory diagram illustrating a cross-sectional configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram showing a schematic electrical configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 4 is an explanatory diagram schematically showing a drive mechanism of an intermediate transfer belt. It is explanatory drawing which shows the example of a correction | amendment of deviation correction. It is explanatory drawing which divides and shows the positional relationship of an intermediate transfer belt and the 1st-3rd sensor from the 1st state to the 6th state. It is explanatory drawing which shows an example of a control table. 3 is a flowchart illustrating control related to an intermediate transfer belt 21 during image formation. It is a flowchart which shows steering control in case the period until predetermined time passes after generation | occurrence | production of the change of an external factor is made into a non-normal time. 5 is a flowchart showing steering control when determining a stable state of the intermediate transfer belt from a detection result of a deviation sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Document 10 ... Image forming apparatus 11 ... Automatic document feeder 11a ... Document loading tray 11b ... Paper discharge tray 12 ... Reading section 13 ... Display operation section 14 ... Control section 15 ... Exposure scanning section 16 ... Line image sensor 17 ... Mirror 18 ... Condensing lens 20 ... Printer unit 21 ... Intermediate transfer belt 22 ... Paper feed unit 22a ... Paper feed cassette 23 ... Transport unit 23a ... Normal path 23b ... Reverse path 24 ... Fixing device 25 ... Secondary transfer roller 26 ... Belt Cleaning devices 30Y, 30M, 30C, 30K ... Image forming units 31Y, 31M, 31C, 31K ... Photoconductors 32Y, 32M, 32C, 32K ... Charging devices 33Y, 33M, 33C, 33K ... Developing devices 34Y, 34M, 34C, 34K ... Cleaning device 35Y, 35M, 35C, 35K ... Writing unit 50 ... Image processing section 51 ... Non-volatile memory 52 ... Belt drive motor 53 ... Shift sensor 53a ... First sensor 53b ... Second sensor 53c ... Third sensor 54 ... Stepping motor 55 ... Pressing / releasing unit 61 ... Drive roller 62 ... Adjustment roller 62a ... Adjustment roller One end (rotation center side)
62b ... The other end (displacement side) of the adjustment roller
63: Movable bearing 65: Concave portion of the intermediate transfer belt 66: Convex portion of the intermediate transfer belt 70: Control table A: Direction of rotation of the photosensitive member B: Circulation direction of the intermediate transfer belt (conveyance direction)
D: Secondary transfer position J: Direction of deviation K: Belt movement direction Q: Correction amount of steering control

Claims (10)

A belt spanned to form a circuit path,
A drive unit for circling the belt;
A detection unit for detecting a position in the width direction of the belt;
A moving part for moving the belt in the width direction;
A control unit that controls the operation of the moving unit based on the detection result of the detection unit so that the deviation of the belt is corrected,
The control unit changes the content of the control when there is a change in an external factor with respect to the belt. A crimping / releasing part that switches between a state in which the belt and another member are crimped and a state in which the crimping is released;
The image forming apparatus according to claim 1, wherein the change in the external factor is the switching. The image forming apparatus according to claim 1, wherein the change in the external factor is a belt driving start. The image forming apparatus according to claim 1, wherein the change in the control content is a change in a control amount of the moving unit with respect to a deviation amount of the belt. The image forming apparatus according to claim 1, wherein the change in the content of the control is a change in a detection cycle by the detection unit. The said control part returns the content of the said control to the content before a change when predetermined time passes, after changing the content of the said control based on the change of the said external factor. The image forming apparatus described. The image forming apparatus according to claim 6, further comprising a changing unit that changes a set value for the predetermined time. When the control unit changes the content of the control due to the occurrence of the external factor, determines whether the belt travel is stable based on the detection result of the detection unit, and determines that it is stable The image forming apparatus according to claim 1, wherein the content of the control is returned to the content before the change. The image forming apparatus according to claim 8, further comprising a determination reference changing unit that changes a reference value of the determination. The image forming apparatus according to any one of claims 1 to 9, wherein the belt is a belt on which an image is formed or abutted against a transfer paper on which an image is formed.

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