JP5233766B2 - Image forming apparatus, photoconductor drive control method, and drive control program - Google Patents

Description

  The present invention forms an image by one color while passing through a plurality of image forming stations and forms a color image by superimposing the images formed by the respective colors, so-called tandem method. Copiers, printers, facsimiles, and image forming apparatuses such as digital multi-function machines having these functions combined, methods for driving and controlling photoreceptors executed by these image forming apparatuses, and these drive control methods using computers The present invention relates to a drive control program for execution.

  Conventionally, as a tandem type image forming apparatus, four color toner images of yellow, cyan, magenta, and black are formed on each photosensitive drum, primarily transferred to an intermediate transfer belt that is an intermediate transfer member, and then transferred onto the intermediate transfer belt. A full color image is formed by superimposing four color images, and then the image is formed by secondary transfer onto the paper to form an image, or the paper that is sucked onto the transport transfer belt and transported in order. A direct transfer system that forms a full color image by superimposing toner images of respective colors one by one is known. In these image forming apparatuses, in order to extend the life of the photosensitive member, the color photosensitive member is separated from the intermediate transfer member during monochrome image formation. At that time, the load of the motor for driving the intermediate transfer belt is different because the number of photosensitive drums in contact with the intermediate transfer belt is different between the color image formation and the monochrome image formation.

  On the other hand, when a color image and a monochrome image are mixed and output, if high productivity is intended, the image forming motor needs to be operated without stopping during the mixed output. However, when the photosensitive drum and the intermediate transfer belt are separated and brought into contact with each other, the load fluctuation of the intermediate transfer belt drive motor becomes large, so that time is required until the speed of the intermediate transfer drive motor is stabilized. Or it may not be stable and fall out of control.

  Therefore, conventionally, before the separation and contact between the photosensitive member and the intermediate transfer device, the image forming motor is temporarily stopped and restarted so as not to become uncontrollable.

  For example, in the invention described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-139063), an endless belt-like member that is stretched around a plurality of rolls and is driven to rotate in a predetermined direction, and a predetermined opposite to the belt-like member. And a plurality of color photoconductors that are juxtaposed to the black photoconductor along the belt-like member and move so as to come into contact with and separate from the belt-like member. In the image forming apparatus in which the black photoconductor and the belt-shaped member are in contact with each other and the color photoconductor is moved away from the belt-shaped member during the monochrome image formation, the monochrome image is formed by a rotation variation suppressing unit. The rotational variation of the belt-like member accompanying the movement of the color photoconductor when forming the toner is suppressed.

  As described above, the drive motor of the intermediate transfer belt in the tandem type color image forming apparatus has different load torques during color image formation and monochrome image formation, and the color photosensitive drum is connected to the intermediate transfer belt during monochrome image formation. By separating, the contact frictional resistance between the photosensitive drum and the intermediate transfer belt changes, and the load torque becomes small. Therefore, when changing from monochrome image formation to color image formation, it has been difficult to stably rotate the motor that drives the intermediate transfer belt.

  In the invention described in Patent Document 1, the load is controlled by the rotation fluctuation suppressing means. However, it cannot be denied that the load fluctuation occurs when the inertial load is connected, and there is a possibility that the image is deteriorated.

  Therefore, a problem to be solved by the present invention is to avoid a sudden increase in the load torque of the intermediate transfer belt motor and prevent image deterioration when changing from monochrome image formation to color image formation.

In order to solve the above-described problems, the present invention provides an image forming method including a color image forming mode in which an image is formed using a plurality of photoconductors and a monochrome image forming mode in which an image is formed using a single photoconductor. an apparatus, wherein the single photosensitive member in the monochrome image forming mode is transferred abutment has been image, the plurality of photosensitive bodies in the color image forming mode is abutting to the image is transferred An image forming medium; contact means for separating the image forming medium from a photosensitive member other than the single photosensitive member in the monochrome image mode; and the image forming mode from the monochrome image forming mode to the color image forming mode. when changing the motor current of the motor for driving the image forming medium, the photosensitive member of the times to be equivalent to the motor current of the monochrome image forming mode Characterized in that it comprises a control means for changing the speed, the.

  In the embodiment described later, the photosensitive member is denoted by reference numeral 1 (1Y, 1C, 1M, 1B), the control means is the main CPU 110, the separation means is the contact / separation motor 16, and the torque instruction value detection means is the pre-driver 220a. The current detection means is the current detection resistor 40, the motor for driving the image forming medium is the intermediate transfer belt motor 15, the intermediate transfer belt is the reference numeral 5, and the image forming medium is the intermediate transfer belt 5 or the conveyance belt 30 including the recording paper. The image recording medium corresponds to a sheet.

According to the present invention, when the transitory color image formed from monochrome image formation, it is possible to avoid a sudden increase in the load torque of the intermediate transfer belt motor, to prevent image deterioration.

1 is a diagram illustrating a schematic configuration of an image forming system of an indirect transfer tandem type image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a schematic configuration of an image forming system of a direct transfer type tandem image forming apparatus according to an embodiment of the present invention. FIG. 3 is a block diagram illustrating a control configuration of a motor drive unit related to image formation in the tandem type image forming apparatus according to the embodiment of the present invention. It is a figure which shows the control structure of the motor shown in FIG. FIG. 5 is a diagram illustrating a relationship between a speed of a photosensitive drum motor and a necessary torque of an intermediate transfer belt motor. 6 is a flowchart illustrating a processing procedure when switching from monochrome image formation to color image formation in the embodiment of the present invention. It is a timing chart which shows the control timing in the process sequence of FIG. 6 is a timing chart showing control timing according to another example when switching from monochrome image formation to color image formation in the embodiment of the present invention. 6 is a flowchart showing a processing procedure when returning to the original speed in order from a photosensitive drum motor positioned on the upstream side of image formation. 10 is a timing chart showing control timing in the processing procedure of FIG. 9. 6 is a flowchart illustrating a processing procedure when detecting an electric current of an intermediate transfer belt motor during color image formation. 6 is a flowchart illustrating a processing procedure when detecting a torque instruction value of the intermediate transfer belt motor 15 during color image formation. 6 is a flowchart illustrating a processing procedure when speed control of a photosensitive drum motor is performed from a current value of the photosensitive drum motor when switching from monochrome image formation to color image formation.

  As described above, the drive motor of the intermediate transfer belt in the tandem type color image forming apparatus has different load torques during color image formation and monochrome image formation, and the color photosensitive drum is connected to the intermediate transfer belt during monochrome image formation. By separating, load torque becomes small. For this reason, when changing from monochrome image formation to color image formation, the motor that drives the intermediate transfer belt cannot rotate stably, and image quality may deteriorate.

  Therefore, in the present embodiment, in order to suppress load fluctuations when changing from monochrome image formation to color image formation, attention is paid to the current flowing through the motor that drives the intermediate transfer belt, and the Y, M, and C colors are exposed during color image formation. The rotational speed of the Y, M, and C photoconductors is controlled to be increased or decreased so that the current flowing to the motor when contacting the body drum is equal to the current flowing to the motor during monochrome image formation. It is characterized by.

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

  FIG. 1 is a diagram showing a schematic configuration of an image forming system of an indirect transfer tandem type image forming apparatus according to the present embodiment.

  In FIG. 1, the image forming apparatus according to the present embodiment is provided with an image forming station of each color for forming an image of each color of Y, M, C, and K. Each image forming station includes a photosensitive drum 1 and a charging device 6, a developing device 2, a transfer device 3, a cleaning device 7, and a static eliminating device 8 arranged along the outer periphery of the photosensitive drum 1. Image stations are arranged in this order in the moving direction of the intermediate transfer belt 5 for each color of Y (yellow), C (cyan), M (magenta), and B (black). In the figure, the Y, C, M, and B subscripts are added to the photoreceptor 1, the charging device 6, the developing device 2, the developing device 2, the primary transfer device 3, the cleaning device 7, and the charge eliminating device 8, respectively, to distinguish the colors. I am doing. It should be noted that, in common with each color, in other words, when the devices are collectively shown, subscripts indicating colors are omitted.

  In this indirect transfer type tandem type image forming apparatus, a single color toner image is formed on each photoconductor 1, and these single color toner images are brought into contact with the intermediate transfer belt 5 and sequentially transferred onto the intermediate transfer belt 5. A composite color image is formed by superimposing a plurality of toner images. On the other hand, the intermediate transfer belt 5 is stretched between the driving roller 21 and the first and second driven rollers 22 and 23, and the transfer belt 24 is stretched between the driving roller and the driven roller as a transfer medium. When the sheet is conveyed, the composite color image on the intermediate transfer belt 5 is transferred to the sheet, guided to a fixing device (not shown), fixed, and then discharged.

  In this image forming apparatus, when transferring an image from each photoconductor 1 to the intermediate transfer belt 5, the transfer devices (transfer rollers) 3Y, 3C, 3M, and 3B are moved up and down as needed at each transfer position. The transfer device 3 moves up and down by driving the contact / separation mechanisms 4YMC and 4B, and can contact and separate from the intermediate transfer belt 5. The latent image is formed by scanning with a laser beam for each color that is modulated based on an image signal from the laser writing unit 9 to each photosensitive member 1.

  FIG. 2 is a diagram showing a schematic configuration of an image forming system of a direct transfer tandem type image forming apparatus. Elements corresponding to those of the tandem image forming apparatus of the indirect transfer type in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  In this direct transfer type tandem image forming apparatus, images of different colors are formed at the respective image forming stations as in the indirect transfer type tandem type image forming apparatus, and are attracted to the transfer conveyance belt 30 and conveyed. A toner image of each color is transferred to the paper at each image forming station, and finally a composite color image is formed on the paper. At the transfer position of each image forming station, transfer devices (transfer rollers) 3Y, 3C, 3M, and 3B move up and down as necessary. The transfer device 3 is driven in the vertical direction by the contact / separation mechanisms 4YCM and 4B, and can be contacted / separated with respect to the transfer conveyance belt 30. Reference numeral 13 denotes a photosensitive drum motor, which corresponds to the photosensitive drum motor 14 in the indirect transfer tandem type image forming apparatus.

  The transfer conveyance belt 30 is stretched between a drive roller 32 and a driven roller 33 that are rotated by a conveyance drive motor 31 and rotates in the direction indicated by an arrow.

  The image forming operation in the tandem image forming apparatus shown in FIGS. 1 and 2 is the same as that of a known image forming apparatus, and is not directly related to the present invention, and therefore will be omitted.

  FIG. 3 is a block diagram showing a control configuration of a motor drive unit related to image formation in the tandem type image forming apparatus. In the figure, the motor drive unit includes a main control unit 100 and a motor control unit 200, and the motor control unit 200 drives the motor 14 that drives the photosensitive drum 1 of each image forming station and the intermediate transfer belt 5. Drive control of the intermediate transfer belt motor 15 is performed.

  The main control unit 100 includes a main CPU 110, an image processing unit 120, and a memory 130. The main CPU 110 controls image data and driving loads related to image formation, here, the contact / separation motor 16 that drives the transfer device 4. The image data is driven by a writing device 20 with a laser beam by a polygon motor 21 to irradiate a polygon mirror that rotates at high speed to form an electrostatic latent image on the photosensitive drum 1.

  The motor control unit 200 includes a driver CPU 210 and a motor drive unit (motor driver) 220 (220B, 220M, 220C, 220Y, 220A). The driver CPU 210 is connected to the main CPU 110, receives commands from the main CPU 110, and receives each photosensitive. Start and stop control of the motor 14 (14B, 14C, 14M, 14Y) that drives the body drum 1 (1B, 1M, 1C, 1Y) and the intermediate transfer belt motor 15, and rotation speed control of the motors 14, 15 Run. In accordance with the instruction received from the main control unit 100, the motor control unit 200 determines the rotational speed of each motor 1 and drives it to rotate. Further, the main control unit 100 determines whether color image formation or monochrome image formation is performed, and the contact / separation motor 16 performs contact / separation control of the color transfer device 4. Reference numeral 17 denotes a sensor for detecting the position of the transfer device 4. Further, the main CPU 110 sends a drive control signal for the intermediate transfer belt motor 15 to the driver CPU 210 based on the position information of the position detection sensor 18 that detects the position of the intermediate transfer belt 5. Each motor control unit 220 drives and controls the motor based on a signal from an encoder 19 (19B, 19M, 19C, 19Y, 19A) attached to each motor 14,15.

  FIG. 4 is a diagram showing a control configuration of the motor shown in FIG. 3. In this embodiment, a three-phase motor is used, and therefore, the configuration of the control unit of the three-phase motor is shown here. In the present embodiment, a pre-driver 220a is disposed at the subsequent stage of the driver CPU 210, and a driver 220b is disposed at the subsequent stage. Here, the motor driver 220 is configured by the pre-driver 220a and the driver 220b. In FIG. 4, the driver CPU 210 monitors the rotation speed of the motor 14 (15) by the encoder 19, converts the motor current from the current detection resistor 40, and monitors Vt. The torque instruction value τ is output to the pre-driver 220a from the monitoring result of the motor rotation speed. An analog value or PWM may be used. The pre-driver 220a controls the magnitude of the current flowing to the motor from the torque instruction value. The pre-driver 220a is connected to the Hall IC 41 and selects a phase to be energized from the rotor position of the motor 14 (15). The driver 220b is composed of an FET or a transistor, converts the level of each phase signal from the pre-driver 220a, and drives the motor 14 (15).

  FIG. 5 is a diagram showing the relationship between the speed of the photosensitive drum motor 14 and the required torque of the intermediate transfer belt motor 15. The dotted line of the speed difference 0 in FIG. 5 indicates that the speed difference between the surface speed of the intermediate transfer belt 5 and the surface speed of the photosensitive drum 1 is 0, the rotational speed of the photosensitive drum motor 14 is slow, and the speed difference is negative. Then, the load on the intermediate transfer belt motor 15 increases due to the dynamic frictional resistance, and the required torque of the motor increases. Further, when the photosensitive drum motor 14 is fast and the speed difference becomes positive, the load on the intermediate transfer belt motor 15 is reduced. Since the photosensitive drum 1 has four colors of B, C, M, and Y, the load when the four photosensitive members 1 come into contact with the intermediate transfer belt 5 and the intermediate transfer belt when one photosensitive member 1 comes into contact with the photosensitive drum 1. The load on the motor 15 is different. Therefore, the speed of the photosensitive drum motor 14 is changed so that the load fluctuation at the time of the change gradually changes. Therefore, in the present embodiment, the photosensitive member for forming a monochrome image from the required torque T2 of the intermediate transfer belt motor 15 when four photosensitive drums 1Y, 1C, 1M, and 1B contact when forming a color image. The peripheral speeds (rotational speeds) of the photosensitive drums 1Y, 1C, and 1M are increased so as to smoothly change to the torque T1 when only 1B contacts.

  FIG. 6 is a flowchart showing a processing procedure when switching from monochrome image formation to color image formation, and FIG. 7 is a timing chart in this processing procedure. However, this example is an example in which the photosensitive drum speed is slower than the intermediate transfer belt speed during image formation. In the timing charts shown in FIG. 7 and FIG. 7 and subsequent figures, in the figure, the vertical axis indicates a slow speed in the positive direction and a fast speed in the negative direction.

  In FIG. 6, if the main CPU 110 determines that the next image formation is a color image formation (step S101-Y), the rotational speeds Vy, Vc, and Vm of the Y, C, and M photoconductor drum motors 14 are set to ΔV. The speed is changed to a higher speed (step S102-TM1). Next, after Ta time, the contact / separation mechanism 4YCM is driven, and the primary transfer devices 3Y, 3C, 3M are moved to bring the intermediate transfer belt 5 into contact with the photosensitive drum 1 (step S103-TM2). Thereafter, at the same time, the rotational speed of the photosensitive drum motor 14 for Y, C, and M colors is changed to the original set speed Vy, Vc, and Vm (step S104-TM3). Note that when returning to the set speeds Vy, Vc, and Vm based on the rotational speed of the photosensitive drum motor 14 from the timing of TM3, the speed is returned at once in the example of FIG. 7, but it may be returned in steps in several steps. Good. Further, in the processing of FIG. 6 and the timing of FIG. 7, the speeds of the three photosensitive drum motors 14 for Y, C, and M are changed, but the speed of at least one photosensitive drum motor 14 may be changed.

  If the photosensitive drum speed is faster than the intermediate transfer belt speed during image formation, the speed is changed to a speed that is slower by ΔV before contacting the intermediate transfer belt 5. The processing procedure itself is the same as the procedure in FIG. 6 except that the relationship between the acceleration and deceleration of the photosensitive drum motor 14 is reversed in the flowchart of FIG. FIG. 8 is a timing chart showing the processing timing at this time.

  As can be seen from FIG. 8, when the main CPU 110 determines that the next image formation is color image formation (step S101-Y), the rotational speeds Vy, Vc, Vm of the photosensitive drum motors 14 for Y, C, M colors. Are respectively changed to a slow speed of ΔV (step S102-TM1 ′). Thereafter, the color transfer device 4YMC is driven after Ta time, and the photosensitive drum 1 and the intermediate transfer belt 5 are brought into contact (step S103-TM2 '). Thereafter, at the same time, the rotational speed of the photosensitive drum motor 14 for Y, C and M colors is returned to the original set speeds Vy, Vc and Vm (step S104-TM3 '). In this case as well, when returning to the set speeds Vy, Vc, Vm based on the rotation speed, the speed may be divided back into several steps.

  An image on which an image is formed by first transferring the developed image on the image bearing member developed with the charged toner in this way onto the intermediate transfer member and then secondarily transferring it from the intermediate transfer member onto the transfer material. In the forming apparatus, the peripheral speed of the intermediate transfer member is set to be faster or slower than the peripheral speed of the image carrier, and the speed difference between the peripheral speeds of the image carrier and the intermediate transfer member is set at the time of transfer. In some cases, it is possible to prevent deterioration in image quality due to a whiteout state of the toner image. Therefore, in this embodiment, a speed difference is provided in order to prevent such image quality deterioration.

  FIG. 9 is a flowchart showing a processing procedure when returning to the original speed in order from the photosensitive drum motor 14 positioned on the upstream side of image formation, that is, when switching from monochrome image formation to color image formation, and FIG. 10 shows the timing at that time. It is a timing chart which shows.

  In FIG. 9, when the main CPU 110 determines that the next image formation is a color image formation, the rotational speeds of the Y, C, and M photoconductor drum motors 14Y, 14C, and 14M are changed to a speed faster by ΔV, respectively (step). S202-TM4). Next, after Ta time, the contact / separation mechanism 4YCM is driven, and the primary transfer devices 3Y, 3C, 3M are moved to bring the intermediate transfer belt 5 into contact with the photosensitive drums 1Y, 1C, 1M (steps S203-TM5 to TM6). . Thereafter, the rotational speed of the Y-color photosensitive drum motor 14Y is changed to the original set speed (steps S204-T7), and after the time Tb has elapsed, the rotational speed of the C-color photosensitive drum motor 14C is changed to the original set speed. Then, after the elapse of Tb time, the rotational speed of the M color photosensitive drum motor 14M is changed to the original set speed (step S206-TM9).

  Note that when returning to the set speed based on the rotational speed of the photosensitive drum motors 14Y, 14C, and 14M, the speed may be returned in several steps. Further, when the next image is formed, the image may be formed immediately after the speeds of the photosensitive drum motors 14Y, 14C, and 14M are returned to the set values.

  FIG. 11 is a flowchart showing a processing procedure for detecting the current of the intermediate transfer belt motor 15 during color image formation.

In the figure, the main CPU 110 drives the contact / separation motor 16 to separate the color transfer devices 3Y, 3M, 3C from the intermediate transfer belt 5 (step S301), and drives the intermediate transfer belt motor 15 (step S302). Next, the current value of the motor 15 when the intermediate transfer belt motor 15 is driven is monitored (step S303a), and the average current Im is stored in the memory 130 (step S304a).

Next, the intermediate transfer belt 5 is brought into contact with the photosensitive drums 1Y, 1C, 1M, the speed of the photosensitive drum motors 14Y, 14C, 14M is changed, and the current It of the intermediate transfer belt motor 15 is changed to the case of monochrome image formation. When the lower limit value for determining whether or not the current is comparable is Im1, and the upper limit value is Im2,
Im1 <It <Im2 (1)
(Steps S306 and S307a). After the adjustment, the speeds Vym, Vcm, Vmm of the photosensitive drum motors 14Y, 14C, 14M at that time are stored (step S308). The currents Im1 and Im2 are equal to the average current Im: Im1 <Im <Im2 (2)
The allowable range for the load is set by the lower limit value Im1 and the upper limit value Im2 of the current. Specifically, it is in a range of about ± 5% with respect to the current value of the intermediate transfer belt motor 15 during monochrome image formation.

  When switching from monochrome image formation to color image formation, the photosensitive drum is set to the speed value of the photosensitive drum motors 14Y, 14C, 14M defined by the current It set by the equations (1) and (2). The intermediate transfer belt 5 is brought into contact with 1Y, 1C, and 1M. The processing shown in the flowchart of FIG. 11 is executed when the power is turned on or when there is a preset temperature change in the internal temperature of the image forming apparatus.

  FIG. 12 is a flowchart showing a processing procedure for detecting a torque instruction value of the intermediate transfer belt motor 15 during color image formation. In FIG. 12, the same processes as those in the flowchart shown in FIG. 11 are denoted by the same reference numerals.

In the figure, the main CPU 110 drives the contact / separation motor 16 to separate the color transfer devices 3Y, 3M, 3C from the intermediate transfer belt 5 (step S301), and drives the intermediate transfer belt motor 15 (step S302). Next, the average torque instruction value of the motor 15 when the intermediate transfer belt motor 15 is driven is monitored (step S303b), and the average torque instruction value τm is stored in the memory 130 (step S304b).

Next, the intermediate transfer belt 5 is brought into contact with the photosensitive drums 1Y, 1C, and 1M, the speed of the photosensitive drum motors 14Y, 14C, and 14M is changed, and the torque instruction value τt of the intermediate transfer belt motor 15 becomes the monochrome image forming. When determining whether or not the torque instruction value is the same level as the case, when the lower limit value is τm1 and the upper limit value is τm2,
τm1 <τt <τm2 (3))
(Steps S306 and S307b). After the adjustment, the speeds Vym, Vcm, Vmm of the photosensitive drum motors 14Y, 14C, 14M at that time are stored (step S308). The lower limit value τm1 and the upper limit value τm2 of the torque instruction value are τm1 <τm <τm2 (4) with respect to the average torque instruction value τm.
Therefore, the allowable range for the load is set from the lower limit value τm1 and the upper limit value τm2 of the torque instruction value. When switching from monochrome image formation to color image formation, the speed values of the photosensitive drum motors 14Y, 14C, and 14M defined by the average torque instruction values set in the above formulas (3) and (4) are used. The body drums 1Y, 1C, and 1M are brought into contact with the intermediate transfer belt 5. The processing shown in the flowchart of FIG. 12 is executed when the power is turned on or when there is a preset temperature change in the internal temperature of the image forming apparatus.

  FIG. 13 shows a processing procedure when the speed control of the photosensitive drum motors 14Y, 14C, 14M is performed from the current values of the photosensitive drum motors 14Y, 14C, 14M when switching from the monochrome image formation to the color image formation. It is a flowchart.

  In the figure, when the main CPU 110 determines that the next image formation is color image formation (step S201b-Y), the speeds of the Y, C, and M color photosensitive drum motors 14Y, 14C, and 14M are changed (step S201b-Y). S202) is driven at the speed stored in the memory 130. Next, the contact / separation mechanism 4YCM is driven, and the primary transfer devices 3Y, 3C, 3M are moved to bring the intermediate transfer belt 5 into contact with the photosensitive drums 1Y, 1C, 1M (step S203). Thereafter, the rotational speeds of the Y-color photosensitive drum motor 14Y, the C-color photosensitive drum motor 14C, and the M-color photosensitive drum motor 14M are changed to the original set speeds (steps S204, S205, and S206). Then, a color image of the next image is formed.

  In the flowchart of FIG. 13, the speeds of the three Y, C, and M photoconductor drum motors 14Y, 14C, and 14M are changed. However, at least one photoconductor drum motor may be changed, or at different timings. You may change it.

As described above, according to the present embodiment,
1) Other than the black photoconductor motor 14BK before the contact between the photoconductor drum 1 and the intermediate transfer belt 5 so that the motor current of the intermediate transfer belt motor 15 is equal between the monochrome image forming mode and the color image forming mode. By changing the rotation speed of the motor, the fluctuation of load torque at the time of contact can be suppressed, so even when shifting from monochrome image formation to color image formation, there is no sudden load fluctuation and high quality Image formation is possible.
2) Since the current value of the intermediate transfer belt motor 15 is stored in advance and the rotational speed of the photosensitive drum motors 14Y, 14C, and 14M is adjusted, load fluctuations before and after contact can be reduced.
3) Since the control torque instruction value of the intermediate transfer belt motor 15 is stored in advance and the rotational speed of the photosensitive drum motors 14Y, 14C, and 14M is adjusted, the load fluctuation before and after the contact can be reduced.
4) Since the speed of the original photosensitive drum motors 14Y, 14C, and 14M is restored after the contact between the photosensitive drums 1Y, 1C, and 1M and the intermediate transfer belt 5, a high-quality image can be formed with respect to color misregistration.
5) Since the speed of the drum motor 14 of the photosensitive drum 1 on the upstream side at the time of image formation is returned to the original speed, it becomes possible to gradually execute the load control of the intermediate transfer belt motor 14 and improve the image quality. Can contribute.
There are effects such as.

  In addition, this invention is not limited to this embodiment, All the technical matters included in the technical idea of the invention described in the claim are object.

  The present invention is applied to an image forming apparatus that forms a color image using a plurality of photoconductors, and is particularly suitable for an image forming apparatus that forms an image by a tandem method.

1, 1Y, 1C, 1M, 1B Photoreceptor 5 Intermediate transfer belt 13Y, 13C, 13M, 13B, 14Y, 14C, 14M, 14B Photoreceptor drum motor 15 Intermediate transfer belt motor 16 Contact / separation motor 30 Transfer conveyer belt 31 Conveyance drive Motor 40 Current detection resistor 110 Main CPU
210 Driver CPU
220 motor driver 220a pre-driver 220b driver

JP 2006-139063 A

Claims (11)

And a color image forming mode for forming an image by using a plurality of photosensitive members, an image forming apparatus having a monochrome image forming mode, the performing the image formation using a single photosensitive member,
In the monochrome image forming mode, an image is transferred by contacting the single photoconductor, and in the color image forming mode, an image forming medium on which the images are transferred by contacting the plurality of photoconductors;
A contact / separation means for separating the image forming medium from a photoconductor other than the single photoconductor in the monochrome image mode;
When the change of the image forming mode from the monochrome image forming mode to the color image forming mode, such that the motor current of the motor for driving the image forming medium, becomes equal to the motor current of the monochrome image forming mode and control means for changing the rotational speed of the photosensitive member,
An image forming apparatus comprising: The image forming apparatus according to claim 1,
The image forming apparatus, wherein the single photosensitive member is a black photosensitive member . The image forming apparatus according to claim 2 ,
When the rotation speed of the photoconductor is slower than the moving speed of the image forming medium, the control unit increases the rotation speed of at least one photoconductor other than the black photoconductor. The image forming apparatus according to claim 2 ,
When the rotational speed of the photoconductor is faster than the moving speed of the image forming medium, the control unit reduces the rotational speed of at least one photoconductor other than the black photoconductor. The image forming apparatus according to any one of claims 2 to 4,
Torque instruction value detection means for detecting a torque instruction value of a motor for rotationally driving the image forming medium is provided, and the torque detected by the torque instruction value detection means is the rotational speed of at least one photoconductor other than the black photoconductor. The image forming apparatus according to claim 1, wherein after the adjustment based on the instruction value, the contact / separation unit contacts the image forming medium with a color photoreceptor other than the black photoreceptor. The image forming apparatus according to any one of claims 2 to 4,
Current detection means for detecting a motor current of a motor that rotationally drives the image forming medium is provided, and the rotational speed of at least one photoconductor other than the black photoconductor is adjusted based on the current detected by the current detection means. Thereafter, the contact / separation means makes the image forming medium contact a photoconductor for color other than the photoconductor for black. The image forming apparatus according to claim 5, wherein:
The image forming apparatus, wherein the control unit gradually returns the photosensitive member and the image forming medium to their original speed after the photosensitive member and the image forming medium are in contact with each other. The image forming apparatus according to claim 7, wherein
The image forming apparatus according to claim 1, wherein the control unit returns the rotational speed of the plurality of photosensitive members to the original speed in order from a driving motor of the photosensitive member disposed upstream of the image formation. The image forming apparatus according to any one of claims 1 to 8,
An image forming apparatus, wherein the image forming medium is an intermediate transfer belt or a conveyance belt. A color image forming mode for forming an image using a plurality of photoconductors, and a monochrome image forming mode for forming an image using a single photoconductor . The photoreceptor is brought into contact with the image forming medium to transfer an image. In the monochrome image forming mode, the single photoreceptor is brought into contact with the image forming medium and a photoreceptor other than the single photoreceptor. Is a drive control method of a photosensitive member of an image forming apparatus in which an image is transferred while being separated from each other,
When the image forming mode is changed from the monochrome image forming mode to the color image forming mode, the motor current of the motor that drives the image forming medium to which the image is transferred in contact with the photosensitive member is changed in the monochrome image forming mode. A method for controlling driving of a photoconductor, wherein the rotational speed of the photoconductor is changed so as to be equal to the motor current. A color image forming mode for forming an image using a plurality of photoconductors, and a monochrome image forming mode for forming an image using a single photoconductor . The photoreceptor is brought into contact with the image forming medium to transfer an image. In the monochrome image forming mode, the single photoreceptor is brought into contact with the image forming medium and a photoreceptor other than the single photoreceptor. A drive control program for a photoconductor for executing drive control of the photoconductor of an image forming apparatus to which an image is transferred by being separated by a computer,
When the image forming mode is changed from the monochrome image forming mode to the color image forming mode, the motor current of the motor that drives the image forming medium to which the image is transferred in contact with the photosensitive member is changed in the monochrome image forming mode. A photosensitive member drive control program comprising a procedure for changing the rotational speed of the photosensitive member so as to be equal to the motor current.

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