JP2005128052A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus shortening the first print time by shortening waiting time caused by the adjustment of a rotational phase with inexpensive constitution. <P>SOLUTION: By setting the rotational phase of a Y photoreceptor drum (rotating body) as reference on which an image is formed first, the difference of the rotational phase is adjusted so that the rotational phases of other M, C and K photoreceptor drums (rotating bodies) may agree with the phase of the Y photoreceptor drum. Thus, the image is formed on the Y rotating body in the midst of adjusting the rotational phases of the M, C and K rotating bodies. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color image forming apparatus, and more particularly to adjustment of a rotational phase of a rotating body thereof.

(Conventional example 1)
FIG. 23 shows images of four colors, that is, yellow (hereinafter referred to as “Y”), magenta (hereinafter referred to as “M”), cyan (hereinafter referred to as “C”), and black (hereinafter referred to as “K”). It is a figure which shows the structure of the color image forming apparatus (conventional example 1) provided with the formation means.

  In FIG. 23, 10a to 10d are photosensitive drums (a, b, c, and d are for Y, M, C, and K, respectively) for forming an electrostatic latent image, and 15a to 15d are for driving the photosensitive drums. It is a motor. Laser scanners 11a to 11d perform exposure according to image signals and form an electrostatic latent image on the photosensitive drum 10. Reference numeral 12 denotes an endless conveyor belt that sequentially conveys paper to each color image forming unit. , A driving roller connected to driving means including a motor and a gear and driving the conveying belt 12, 15e a motor driving the driving roller 13, and 14 a fixing device for melting and fixing the toner transferred onto the paper; Reference numerals 16 a to 16 d denote phase detection sensors that detect the rotational phase of the photosensitive drum 10.

  When data to be printed is sent from the PC to the printer and image formation according to the method of the printer engine is completed and printing is possible, paper 17 is supplied from a paper cassette (not shown) in the direction of the arrow and reaches the conveyor belt 12. Then, the paper 17 is sequentially conveyed to the image forming units of the respective colors by the conveying belt 12. The image signal of each color is sent to each laser scanner 11 in synchronism with the conveyance of the paper by the conveyance belt 12, and an electrostatic latent image is formed on the photosensitive drum 10. The electrostatic latent image is electrostatically applied to the photosensitive drum 10 by a developing device (not shown). The latent image is developed with toner and transferred onto the paper 17 at a transfer portion where the photosensitive drum 10 and the conveyance belt 12 are in contact with each other. In the figure, images are sequentially formed in the order of Y, M, C, and K. Thereafter, the paper 17 is separated from the conveyance belt, and the toner image is fixed on the paper 17 by heat by the fixing device 14 and discharged to the outside.

  By the way, in the color image forming apparatus configured as described above, the mismatch of the image forming positions of the respective colors appears in the image as a color shift, which leads to deterioration in image quality.

  Color misregistration includes regular color misregistration (hereinafter referred to as DC color misregistration) that occurs due to positional misalignment when assembling the developing devices for each color, and periodic color that occurs due to shaft flutter of the rotating body. It can be roughly divided into shifts (hereinafter referred to as AC color shifts).

  Among these, as a measure against AC color misregistration, a method of individually controlling the rotation phase of each color rotator is known. Specifically, when the motors 15a to 15d are started, rotation control of the motors 15a to 15c is performed so that the rotation phases of the photosensitive drums 10a to 10c are matched with reference to the rotation phase of the photosensitive drum 10d.

  FIG. 24 is a timing chart showing the operation of the conventional example. The description of FIG.

  At the time of 0 second, the start-up of the motors 15a to 15d of the respective colors is started, and the start-up is completed to a steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16d detects the rotational phase of the reference K photosensitive drum 10d, and the phase detection sensors 16a to 16c detect the phases of the other photosensitive drums 10a to 10c. Detect. A phase difference is calculated based on the detection result, and is adjusted so that the rotational phase of the K photosensitive drum 10d and the rotational phases of the other color photosensitive drums 10a to 10c are matched within 1 to 2 seconds. As a result, image formation can be started 2 seconds after the start-up.

(Conventional example 2)
FIG. 25 is a diagram showing a color image forming apparatus (conventional example 2) having image forming means for four colors.

  In FIG. 25, 10a to 10d are photosensitive drums (a, b, c, and d are for Y, M, C, and K, respectively) for forming electrostatic latent images, and 15abc and 15d are for driving the photosensitive drums. It is a motor.

  Laser scanners 11a to 11d perform exposure according to image signals and form an electrostatic latent image on the photosensitive drum 10. Reference numeral 12 denotes an endless conveyor belt that sequentially conveys paper to each color image forming unit. , A driving roller connected to driving means including a motor and a gear and driving the conveying belt 12, 15e a motor driving the driving roller 13, and 14 a fixing device for melting and fixing the toner transferred onto the paper; 16abc is a phase detection sensor that detects the rotational phase of the photosensitive drums 10a to 10c, and 16d is a phase detection sensor that detects the rotational phase of the photosensitive drum 10d. The YMC photosensitive drums 10a to 10c are adjusted to have the same phase and mechanically connected to each other, and are driven by the motor 15abc in a state where the phases are always aligned.

  When data to be printed is sent from the PC to the printer and image formation according to the method of the printer engine is completed and printing is possible, paper 17 is supplied from a paper cassette (not shown) in the direction of the arrow and reaches the conveyor belt 12. Then, the paper 17 is sequentially conveyed to the image forming units of the respective colors by the conveying belt 12. The image signal of each color is sent to each laser scanner 11 in synchronism with the paper conveyance by the conveyance belt 12, and an electrostatic latent image is formed on the photosensitive drum 12, and electrostatically is applied to the photosensitive drum 10 by a developing device (not shown). The latent image is developed with toner and transferred onto the paper 17 at a transfer portion where the photosensitive drum 10 and the conveyance belt 12 are in contact with each other. In the figure, images are sequentially formed in the order of Y, M, C, and K. Thereafter, the paper 17 is separated from the conveyance belt, and the toner image is fixed on the paper 17 by heat by the fixing device 14 and discharged to the outside.

  By the way, in the color image forming apparatus configured as described above, the mismatch of the image forming positions of the respective colors appears in the image as a color shift, leading to deterioration of image quality. Color misregistration includes steady color misregistration (DC color misregistration) that occurs due to positional misalignment when assembling the developing devices for each color, and periodic color misregistration (AC color misregistration) that occurs due to shaft rotation of the rotating body. ).

  Among these, as a measure against AC color misregistration, a method of individually controlling the rotation phase of each color rotator is known. Specifically, when the motors 15abc and 15d are activated, the rotation phase of the YMC photosensitive drums 10a to 10c is matched with the rotational phase of the K photosensitive drum 10d on the basis of the rotational phase of the K photosensitive drum 10d. Rotation control is performed.

  FIG. 26 is a timing chart showing the operation of this conventional example. The description of FIG.

  Start-up of the motors 15abc and 15d is started at the time of 0 seconds, and the start-up is completed to a steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16d detects the rotational phase of the reference K photosensitive drum 10d, and the phase detection sensor 16abc detects the rotational phase of the YMC photosensitive drums 10a to 10c. To do. Based on the detection result, the phase difference between the rotational phase of the photosensitive drum 10d and the rotational phase of the photosensitive drums 10a to 10c is calculated, and the rotational phase of the K photosensitive drum 10d and the photosensitive phase of YMC are calculated within 1 to 2 seconds. Adjustment is made so that the rotational phases of the drums 10a to 10c are matched. As a result, the phase adjustment is completed 2 seconds after the start-up, and image formation can be started.

A technique related to Patent Document 1 below is described.
No. 2003-211943

  The methods of the conventional examples 1 and 2 have the following problems.

  Since the rotation phase adjustment sequence is executed as necessary when the motor is started, image formation must be waited until this phase adjustment is completed, and the wait time due to phase adjustment causes the first printout time to be extended. It was.

  The present invention has been made under such circumstances, and it is an object of the present invention to provide a color image forming apparatus capable of shortening the waiting time by rotational phase adjustment and shortening the first print time with an inexpensive configuration. Yes.

  In order to solve the above problems, in the present invention, a color image forming apparatus is configured as described in the following (1) to (7).

(1) A plurality of rotating bodies each carrying an image of each color, and a plurality of driving each of the plurality of rotating bodies, respectively driving the plurality of rotating bodies, or dividing the plurality of rotating bodies into a plurality of groups. Motors, a plurality of detection means for detecting rotation phases of the plurality of rotation bodies or the plurality of rotation body groups, respectively, and the plurality of rotation bodies or the plurality of rotations based on detection results of the plurality of detection means. A color image forming apparatus that includes an adjusting unit that adjusts the rotational phase difference of the body group and suppresses color misregistration by adjusting the rotational phase difference;
The adjusting means uses the rotational phase of the first rotating body or the rotating body group including the rotating body for image formation as a reference so that the rotational phase of the rotating body or the rotating body group matches the rotational phase. A color image forming apparatus that adjusts the phase difference.

(2) In the color image forming apparatus according to (1),
In the case where image formation is performed using two or more and less than all of the rotating bodies, the adjusting means rotates the rotation body on the basis of the rotation phase of the rotating body that performs image formation first or the rotating body group that includes the rotating bodies. A color image forming apparatus that adjusts the rotational phase difference so that the rotational phase of another rotating body or group of rotating bodies matches the phase.

(3) In the color image forming apparatus according to (1) or (2),
A color image forming apparatus which starts image formation of the reference rotating body or a rotating body group including the rotating body while adjusting the rotational phase difference.

(4) A plurality of rotating bodies each carrying an image of each color, and a plurality of driving each of the plurality of rotating bodies, each driving the plurality of rotating bodies, or dividing the plurality of rotating bodies into a plurality of groups. Motors, a plurality of detection means for detecting rotation phases of the plurality of rotation bodies or the plurality of rotation body groups, respectively, and the plurality of rotation bodies or the plurality of rotations based on detection results of the plurality of detection means. A color image forming apparatus that includes an adjusting unit that adjusts the rotational phase difference of the body group and suppresses color misregistration by adjusting the rotational phase difference;
The adjusting means rotates on the basis of the rotational phase of the rotating body or the rotating body group having the element that takes the longest time for phase adjustment so that the rotating phase of the rotating body or the rotating body group matches the rotational phase. A color image forming apparatus that adjusts the phase difference.

(5) In the color image forming apparatus according to (4),
The color image forming apparatus, wherein the element is a load torque for a motor that drives the rotating body or the group of rotating bodies.

(6) In the color image forming apparatus according to (4),
The color image forming apparatus, wherein the element is a load inertia for a motor that drives the rotating body or the group of rotating bodies.

(7) In the color image forming apparatus according to (4),
The color image forming apparatus, wherein the element is a transmission delay from a motor that drives the rotating body or the rotating body group to the rotating body or the rotating body group.

  According to the present invention, it is possible to provide a color image forming apparatus capable of reducing the waiting time by rotational phase adjustment and shortening the first print time with an inexpensive configuration.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  FIG. 1 is a diagram illustrating a configuration of a “color image forming apparatus” according to the first embodiment. With respect to the photosensitive drums 10a to 10d in the figure, the phase adjustment according to the present invention is performed to suppress color misregistration. Since other configurations and functions are the same as those of the conventional example 1 (FIG. 23), the description thereof is used and the description thereof is omitted here.

  FIG. 2 is a block diagram showing a schematic configuration of the control system in the present embodiment. Reference numeral 20 denotes a printer as a color image forming apparatus. A printer control unit 21 controls each device in the printer. A power supply 22 supplies power to each device in the printer. Reference numerals 23 denote sensors for detecting the status of each unit in the printer. A motor control unit 24 controls the motors according to instructions from the printer control unit 21. Reference numeral 25 denotes motors which are power sources of the respective devices in the printer. A display unit 26 notifies the user of the operation status of the printer. A communication controller 27 performs communication between the printer 20 and the host computer. A host computer 28 transfers data to be printed to the printer 20.

  FIG. 3 is a diagram showing the configuration of the main part of the present embodiment. Reference numeral 30 denotes a DSP (digital signal processor), 31 denotes a motor, 32 denotes a driver for controlling electric power to the motor 31, and 33 denotes a rotating body such as a photosensitive drum driven by the motor 31. A flag 35 is provided on the shaft 34 of the rotating body 33, and the optical path of the photosensor 36 is blocked as the shaft 34 rotates. As a result, a signal is output once for each rotation of the shaft. Alternatively, a configuration may be adopted in which a flag is provided in the rotating body or a gear that drives the rotating body, and the flag shields the photosensor.

  The DSP 30 adjusts the rotational phase of the motor (position control), the motor start / stop control based on the control signal from the printer control unit 21, and compares the speed signal from the printer control unit 21 with the output of the speed detection means. Speed control is performed via

  Next, a case where the reference rotating body is the photosensitive drum 10a and the drive control of the photosensitive drum 10b is performed will be described with reference to FIGS.

  When the motor activation is instructed from the printer control unit 21 (step 1), the motor control unit 21 performs speed control and position control for each motor, and minimizes the relative speed of each motor. The position command is updated in accordance with a predetermined acceleration curve to accelerate (step 2). When all the motors reach the steady rotational speed, the acceleration is finished (step 3).

  Next, when the printer control unit 21 instructs execution of the phase adjustment execution determination for each drum (step 4), detection of the rotational phase difference between the photosensitive drum 10a and the photosensitive drum 10b serving as a reference is started. That is, when the signal from the phase detection sensor 16a of the photosensitive drum 10a serving as a reference is output, the time measurement counter value cnt is cleared (steps 5 and 6), and then the count value cnt is increased at a constant cycle (step). 7). When the signal from the phase detection sensor 16b of the photosensitive drum 10b is output, the increase of the count value cnt at the time is stopped (step 8), the measured time is converted into the phase difference of each drum, and the position error information of the motor (Step 9). Then, the phase difference of each photosensitive drum is compared with a predetermined value to determine whether or not the phase adjustment of each drum is necessary (step 10), and the result is notified to the printer control unit 21 (step 11).

  The printer control unit 21 receives the notified phase adjustment execution determination result of each drum, executes the print sequence when the phase adjustment execution is unnecessary, and executes the phase adjustment to the motor control unit 24 when the phase adjustment execution is necessary. And the print sequence is executed after completion of the phase adjustment.

  When the motor control unit 24 is instructed to execute the phase adjustment from the printer control unit 21 (step 51), the motor control unit 24 feeds back the motor position error information obtained by the phase adjustment execution determination operation to the motor position control loop, and calculates the position error. Control is performed so as to cancel (step 52). If the phase difference to be adjusted is equal to or smaller than a certain value (for example, 30 °) (step 53), image formation is started in parallel with the phase adjustment after a predetermined time (step 54) (step 55). When the phase difference is larger than a certain value (for example, 30 °) (step 53), image formation is started after completion of the phase adjustment (step 56) (step 55).

  At this time, the value of each parameter used for the operation amount calculation of the position control loop may be changed depending on the absolute value of the position error information. For example, when the absolute value of the position error information is large, the gain of the position control loop is reduced to ensure control stability.

  FIG. 6 is a timing chart showing the operation of this embodiment. The description of FIG.

  At the time of 0 second, the start-up of the motors 15a to 15d of the respective colors is started, and the start-up is completed to a steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16a detects the rotational phase of the Y photosensitive drum 10a serving as a reference, and the phase detection sensors 16b to 16d detect the phases of the other photosensitive drums 10b to 10d. Detect. Based on the detection result, a phase difference is calculated, and the rotational phase of the Y photosensitive drum 10a is used as a reference for another photosensitive drum 10b to 10d within a period of 1 to 2 seconds. Make adjustments so that the rotation phase matches. Here, Y image formation is started 0.5 seconds later from 2.0 seconds after completion of M phase adjustment so that M image formation can be started immediately after completion of phase adjustment of M photosensitive drum 10b. . Therefore, image formation can be started 1.5 seconds after the start-up. If phase adjustment is not completed at the time of 2.0 seconds, the Y image already formed on the photosensitive drum and the paper on which a part of the Y image is transferred are discharged as misprinting. To do.

  In this embodiment, the image forming apparatus using the paper conveyance belt 12 has been described as an example. However, the present invention is not necessarily limited to this, and the same applies to an image forming apparatus using an intermediate transfer unit such as an intermediate transfer belt. The effect can be expected. Further, in the configuration using the intermediate transfer means, even if the phase adjustment is not completed at the time of 2.0 seconds, the image is not transferred onto the paper at that time, so the image has already been formed on the photosensitive drum. You only need to discard the image. Thereafter, image formation may be performed again from Y when phase adjustment is completed.

  As described above, in this embodiment, the phase adjustment of the photosensitive drums of the other colors is performed with reference to the rotational phase of the Y photosensitive drum 10a where image formation is first performed, and Y image formation is started during that time. Accordingly, it is possible to reduce the waiting time by phase adjustment and reduce the first print time with an inexpensive configuration.

  A “color image forming apparatus” that is Embodiment 2 will be described. In the present embodiment, the schematic configuration of the control system, the configuration of the main part, and the like are the same as those in the first embodiment, so that the description thereof will be omitted, and the configuration and operation unique to the present embodiment will be described.

  FIG. 7 is a block diagram showing the configuration of this embodiment. In the figure, components having the same functions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  A motor 15f drives the photosensitive drums 10a and 10b, and a motor 15g drives the photosensitive drums 10c and 10d. The photosensitive drums 10a and 10b and the photosensitive drums 10c and 10d are mechanically coupled after adjusting their rotational phases to be the same phase (corresponding to the rotating body group in the claims). Reference numeral 16f denotes a phase detection sensor for detecting the rotational phase of the photosensitive drums 10a and 10b, and reference numeral 16g denotes a phase detection sensor for detecting the rotational phase of the photosensitive drums 10c and 10d. This embodiment is different from the first embodiment in a configuration in which a plurality of photosensitive drums are driven by one motor.

  FIG. 8 is a timing chart showing the operation of this embodiment. The description of FIG.

  The start-up of the two motors 15f and 15g is started at the time of 0 second, and the start-up is completed to the steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16f detects the rotational phases of the Y and M photosensitive drums 10a and 10b serving as a reference, and the phase detection sensor 16g detects the C and K photosensitive drums 10c and 10c. 10d phase is detected. Based on the detection result, the phase difference is calculated, and the rotational phase of the Y and M photosensitive drums 10a and 10b is used as a reference during one to two seconds with reference to the rotational phase of the Y and M photosensitive drums 10a and 10b. In addition, adjustment is made so that the rotational phases of the C and K photosensitive drums 10c and 10d are matched.

  Here, Y image formation is started 1.0 second backward from 2.0 seconds after completion of C phase adjustment so that image formation can be started immediately after completion of phase adjustment of C photosensitive drum 10c. Accordingly, image formation can be started 1.0 second after the start-up.

  As described above, in the present embodiment, the phase adjustment of the other photosensitive drum groups is performed with reference to the rotational phase of the photosensitive drum group including the Y photosensitive drum 10a that first performs image formation, and Y, M in the meantime. By starting the image formation, it is possible to reduce the waiting time by the phase adjustment and shorten the first print time with an inexpensive configuration.

  In this embodiment, the photosensitive drums 10a and 10b, the photosensitive drums 10c and 10d, and the two photosensitive drums are grouped. However, the present invention is not limited to this. For example, the photosensitive drums 10a, 10b, and photosensitive drums are not necessary. The present invention can be similarly implemented by using one part of the photosensitive drum group as one photosensitive drum so that the drums 10c and 10d are each in one group.

  A “color image forming apparatus” that is Embodiment 3 will be described. In the present embodiment, the schematic configuration of the control system, the configuration of the main part, and the like are the same as those in the first embodiment, so that the description thereof will be omitted and the configuration unique to the present embodiment will be described.

  FIG. 9 is a block diagram showing the configuration of this embodiment. In the figure, components having the same functions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. This embodiment relates to rotational phase adjustment in the case of image formation with fewer colors than the image formation with all the colors Y, M, C and K described in the prior art 1 and the first embodiment. It is.

  In the following, description will be given by taking as an example the case of image formation in the two-color mode of M and K. In this case, the rotational phases of the Y and C photosensitive drums 10a and 10c where image formation is not performed do not affect the image. Therefore, the rotational phases of the M and K photoconductive drums 10b and 10d for image formation may be matched (however, the Y and C photoconductive drums 10a and 10c are also in contact with the transport belt 12 and thus rotate).

  FIG. 10 is a timing chart showing the operation of this embodiment. The description of FIG.

  At the time of 0 second, the start-up of the motors 15a to 15d of the respective colors is started, and the start-up is completed to a steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16b detects the rotational phase of the M photosensitive drum 10b as a reference, and the phase detection sensor 16d detects the phase of the K photosensitive drum 10d. The phase difference is calculated based on the detection result, and the rotation of the K photosensitive drum 10d is rotated to the rotation phase of the M photosensitive drum 10b with reference to the rotation phase of the M photosensitive drum 10b within 1 to 2 seconds. Adjust so that the phase matches. Here, so that the image formation by the K photosensitive drum 10d can be started immediately after the phase adjustment of the K photosensitive drum 10d is completed, the M image is traced back from 2.0 seconds to 1.0 second after the K phase adjustment is completed. Start forming. Accordingly, image formation can be started 1.0 second after the start-up.

  As described above, in this embodiment, the photosensitive drum 10d of the K photosensitive drum 10d is based on the rotational phase of the M photosensitive drum 10b that first performs image formation in the two-color mode in which image formation is less than when printing all colors. By performing phase adjustment and starting M image formation during that time, it is possible to reduce the waiting time for phase adjustment and shorten the first print time with an inexpensive configuration.

  In this embodiment, the photosensitive drums 10a, 10b, 10c, and 10d are driven by separate motors. However, the present invention is not limited to this. For example, the photosensitive drums 10a, 10b, and 10d and 10d are not limited thereto. In the same manner, the photosensitive drums can be grouped and driven by separate motors so that each is a group.

  FIG. 11 is a diagram illustrating a configuration of a “color image forming apparatus” according to the fourth embodiment. With respect to the photosensitive drums 10a to 10d in the figure, the phase adjustment according to the present invention is performed to suppress color misregistration. Since other configurations and functions are the same as those of the conventional example 2 (FIG. 25), the description thereof is incorporated and the description thereof is omitted here.

  FIG. 12 is a block diagram showing a schematic configuration of the control system in the present embodiment. Reference numeral 120 denotes a printer as a color image forming apparatus. A printer control unit 121 controls each device in the printer. A power supply 122 supplies power to each device in the printer. Reference numeral 123 denotes sensors for detecting the status of each unit in the printer. A motor control unit 124 controls the motors according to instructions from the printer control unit 121. Reference numeral 125 denotes motors which are power sources of the respective devices in the printer. A display unit 126 notifies the user of the operation status of the printer 120. A communication controller 127 performs communication between the printer 120 and the host computer. A host computer 128 transfers data to be printed to the printer 120.

  FIG. 13 is a diagram showing the configuration of the main part of this embodiment.

  Reference numeral 130 denotes a DSP (digital signal processor), 131 denotes a motor, 132 denotes a driver for controlling electric power to the motor, and 133 denotes a rotating body such as a photosensitive drum driven by the motor. A flag 135 is provided on the shaft 134 of the rotating body 133, and the optical path of the photosensor 136 is blocked as the shaft 134 rotates. As a result, a signal is output once for each rotation of the shaft. Alternatively, a configuration may be adopted in which a flag is provided in the rotating body or a gear that drives the rotating body, and the flag shields the photosensor.

  The DSP 130 adjusts the rotational phase of the motor (position control), starts and stops the motor according to the control signal from the printer control unit 121, compares the speed signal from the printer control unit 121 and the output of the speed detection means, and compares the driver 132 with the driver 132. Speed control is performed via

  Next, a phase adjustment method in this embodiment, that is, a case where the reference rotating body is the YMC photosensitive drums 10a to 10c and the phase adjustment of the K photosensitive drum 10b is performed will be described with reference to FIGS. .

  When the motor activation is instructed from the printer control unit 121 (step 141), the motor control unit 121 performs speed control and position control for each motor, and minimizes the relative speed of each motor. The position command is updated according to a predetermined acceleration curve to accelerate the vehicle (step 142). When all the motors reach the steady rotational speed, the acceleration is finished (step 143).

  Next, when the printer control unit 121 instructs execution of the phase adjustment execution of each drum (step 144), the rotational phase difference between the YMC photosensitive drums 10a to 10c serving as a reference and the K photosensitive drum 10d is determined. Start detection. That is, when a signal from the phase detection sensor 16abc of the YMC photosensitive drums 10a to 10c serving as a reference is output, the time measurement counter value cnt is cleared (steps 145 and 146), and then the count value cnt is set at a constant cycle. Increase (step 147). When the signal from the phase detection sensor 16d of the K photosensitive drum 10d is output, the increase of the count value cnt at the time point is stopped (step 148), the measured time is converted into the phase difference of each drum, and the position of the motor Conversion into error information (step 149). Then, the phase difference of each drum is compared with a predetermined value to determine whether or not the phase adjustment of each drum needs to be executed (step 150), and the result is notified to the printer control unit 121 (step 151).

  The printer control unit 121 receives the notified phase adjustment execution determination result of each drum, and executes the printing sequence when the phase adjustment execution is unnecessary, and executes the phase adjustment to the motor control unit 121 when the phase adjustment execution is necessary. And the print sequence is executed after completion of the phase adjustment.

  When the motor control unit 124 is instructed to execute the phase adjustment from the printer control unit 121 (step 161), the motor control unit 124 feeds back the motor position error information obtained by the phase adjustment execution determination operation to the motor position control loop, and the position error is calculated. Control is performed so as to cancel (step 162). Then, after phase adjustment is completed (step 163), image formation is started (step 164).

  At this time, the value of each parameter used for the operation amount calculation of the position control loop may be changed depending on the absolute value of the position error information. For example, when the absolute value of the position error information is large, the gain of the position control loop is reduced to ensure control stability.

  FIG. 16 is a timing chart showing the operation of this embodiment. The description of FIG.

  The start-up of the motors 15abc and 15d is started at the time of 0 second, and the start-up is completed to the steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16abc detects the rotational phase of the YMC photosensitive drums 10a to 10c serving as a reference, and the phase detection sensor 16d detects the phase of the K photosensitive drum 10d. . Based on the detection result, a phase difference is calculated, and the rotational phase of the YMC photosensitive drums 10a to 10c is set so that the rotational phase of the K photosensitive drum 10d matches the rotational phase of the YMC photosensitive drums 10a to 10c. adjust. Here, since the load torque of the motor d is about 1/3 of the load torque of the motor abc, the time required for the phase adjustment can be further reduced. For example, in the conventional example 2, the phase adjustment takes 1.0 second, whereas the phase adjustment is completed in half of 0.5 seconds. Therefore, in this embodiment, the phase adjustment is completed 1.5 seconds after the start of the start-up, and image formation can be started, and the first printout time can be shortened by 0.5 seconds compared to the conventional example 2.

  As described above, in this embodiment, the phase adjustment of the K photosensitive drum 10d is performed on the basis of the rotational phase of the YMC photosensitive drums 10a to 10c driven by the motor 15abc having the largest load torque. With a simple configuration, it is possible to shorten the waiting time by phase adjustment and shorten the first print time.

  A “color image forming apparatus” that is Embodiment 5 will be described. Since the schematic configuration of the control system of the present embodiment, the configuration of the main part, and the like are the same as those of the fourth embodiment, description thereof will be omitted, and the configuration unique to the present embodiment will be described.

  FIG. 17 is a diagram showing the configuration of this embodiment. In the figure, components having the same functions as those in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted.

  A motor 15 d drives the photosensitive drum 10 d and the driving roller 13. The present embodiment is different from the first embodiment in the configuration in which the motor 15de drives both the photosensitive drum 10d and the conveying belt 12 having a large inertia.

  FIG. 18 is a timing chart showing an operation in the case of using the same method as that of the conventional example 2 in the configuration of this embodiment, specifically, an operation in the case of performing phase adjustment based on the photosensitive drums 10a to 10c. The description of FIG.

  The start of the motors 15abc and 15de is started at the time of 0 second, and the start-up is completed to the steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16abc detects the rotational phase of the YMC photosensitive drums 10a to 10c serving as a reference, and the phase detection sensor 16d detects the phase of the K photosensitive drum 10d. . Based on the detection result, a phase difference is calculated and adjusted so that the rotational phase of the K photosensitive drum 10d matches the rotational phase of the YMC photosensitive drums 10a to 10c. Here, since the motor 15de must drive the photosensitive drum 10d and the conveying belt 12 having a large inertia, it takes 1.5 seconds to adjust the phase. As a result, the phase adjustment is completed 2.5 seconds after the start-up, and image formation can be started.

  FIG. 19 is a timing chart of the present embodiment. In the figure, the method is different from the method of the conventional example 2 in that phase adjustment is performed with the photosensitive drum 10d as a reference. The description of FIG.

  Start-up of the motors 15abc and 15d is started at the time of 0 seconds, and the start-up is completed to a steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16d detects the rotational phase of the reference K photosensitive drum 10d, and the phase detection sensor 16abc detects the phases of the YMC photosensitive drums 10a to 10c. . Based on the detection result, a phase difference is calculated and adjusted so that the rotational phase of the YMC photosensitive drums 10a to 10c matches the rotational phase of the K photosensitive drum 10d with reference to the rotational phase of the K photosensitive drum 10d. . Here, since the load inertia of the motor 15abc is less than that of the motor 15de, the time required for the phase adjustment can be reduced. For example, the method of Conventional Example 2 requires 1.5 seconds for phase adjustment, whereas in this embodiment, phase adjustment is completed in 1.0 seconds. Therefore, in this embodiment, phase adjustment is completed 2.0 seconds after the start of startup, and image formation can be started, and the first printout time can be shortened by 0.5 seconds compared to the method of Conventional Example 2. Become.

  As described above, in this embodiment, the phase of the photosensitive drums 10a to 10d of YMC is adjusted based on the rotational phase of the photosensitive drum 10d of K driven by the motor 15d having the largest load inertia. With a simple configuration, it is possible to shorten the waiting time by phase adjustment and shorten the first print time.

  A “color image forming apparatus” that is Embodiment 6 will be described. Since the schematic configuration of the control system of the present embodiment, the configuration of the main part, and the like are the same as those of the fourth embodiment, description thereof will be omitted, and the configuration unique to the present embodiment will be described.

  FIG. 20 is a diagram showing the configuration of this embodiment. In the figure, components having the same functions as those in the fourth embodiment are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 20, 15a to 15c are motors for driving the photosensitive drums 10a to 10c, 16a to 16d are phase detection sensors for detecting the rotational phases of the photosensitive drums 10a to 10c, and 18 is for driving the motor 15d. This is a drive gear train for transmitting to the photosensitive drum 10d. In this embodiment, the drive gears of the photosensitive drums 10a to 10c are directly driven by the motors 15a to 15c, but the drive gear of the photosensitive drum 10d is driven from the motor 15d via the drive gear train 18 because of space. This is an example.

  FIG. 21 is a timing chart in the case where the same method (see FIG. 24) as in Conventional Example 1 is used in the configuration of this embodiment, and specifically, the phase adjustment is sequentially performed based on the photosensitive drum 10a. The description of FIG.

  The start-up of the motors 15a to 15d is started at the time of 0 seconds, and the start-up is completed to the steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16a detects the rotational phase of the Y photosensitive drum 10a serving as a reference, and the phase detection sensors 16b to 16d detect the phases of the MCK photosensitive drums 10b to 10d. Detect. Based on the detection result, a phase difference is calculated and adjusted so that the rotational phase of the MCK photosensitive drums 10b to 10d matches the rotational phase of the Y photosensitive drum 10a with reference to the rotational phase of the Y photosensitive drum 10a. . Here, the photosensitive drum 10d takes 1.0 second to adjust the phase because of the transmission delay caused by the drive gear train 18. As a result, the phase adjustment is completed 2.0 seconds after the start of startup, and image formation can be started.

  FIG. 22 is a timing chart showing the operation of this embodiment. In the figure, the method is different from the conventional method 1 in that the phase adjustment is performed with reference to the photosensitive drum 10d. The description of FIG.

  The start-up of the motors 15a to 15d is started at the time of 0 seconds, and the start-up is completed to the steady speed by 0.5 seconds. Thereafter, between 0.5 and 1 second, the phase detection sensor 16d detects the rotational phase of the K photosensitive drum 10d serving as a reference, and the phase detection sensors 16a to 16c detect the phases of the YMC photosensitive drums 10a to 10c. Detect. A phase difference is calculated based on the detection result, and the rotational phase of the YMC photosensitive drums 10a to 10c is set so that the rotational phase of the K photosensitive drum 10d matches the rotational phase of the YMC photosensitive drums 10a to 10c. adjust.

  Here, since the transmission delay from the motors 15a to 15c to the photosensitive drums 10a to 10c is much smaller than the transmission delay from the motor 15d to the photosensitive drum 10d, the time required for the phase adjustment can be reduced. For example, in the same method as in the conventional example 1 described above, the phase adjustment takes 1.0 seconds, whereas in this embodiment, the phase adjustment is completed in 0.5 seconds. Accordingly, in this embodiment, the phase adjustment is completed 1.5 seconds after the start of the start-up, and image formation can be started, and the first printout time is shortened by 0.5 seconds as compared with the conventional technique 1 described above. It becomes possible.

  As described above, in this embodiment, the phase of the YMC photosensitive drums 10a to 10d is adjusted based on the rotational phase of the K photosensitive drum 10d driven by the motor 15d having the longest transmission delay, thereby reducing the cost. With a simple configuration, it is possible to shorten the waiting time by phase adjustment and shorten the first print time.

(Deformation)
Each of the above embodiments relates to the adjustment of the rotational phase of a plurality of photosensitive drums for image holding. However, the same configuration is applied to the adjustment of the rotational phase of a plurality of transfer drums for image holding. be able to.

The figure which shows the structure of Example 1. Diagram showing schematic configuration of control system Diagram showing the configuration of the main part Flowchart showing the operation of the first embodiment. Flowchart showing the operation of the first embodiment. Timing chart showing operation of embodiment 1 The figure which shows the structure of Example 2. Timing chart showing operation of embodiment 2 The figure which shows the structure of Example 3. Timing chart showing operation of embodiment 3 The figure which shows the structure of Example 4. Diagram showing schematic configuration of control system Diagram showing the configuration of the main part Flowchart showing the operation of the fourth embodiment. Flowchart showing the operation of the fourth embodiment. Timing chart showing operation of embodiment 4 The figure which shows the structure of Example 5. Timing chart showing operation by the same method as in Conventional Example 2 Timing chart showing operation of embodiment 5 The figure which shows the structure of Example 6. Timing chart showing operation by a method similar to that in Conventional Example 1 Timing chart showing operation of embodiment 6 The figure which shows the structure of the prior art example 1. Timing chart showing operation of Conventional Example 1 The figure which shows the structure of the prior art example 2. Timing chart showing operation of Conventional Example 2

Explanation of symbols

10a to 10d Photosensitive drum (rotating body)
15a to 15d Motors 16a to 16d Phase detection sensor 30 DSP

Claims (7)

A plurality of rotating bodies each carrying an image of each color; and a plurality of motors for driving the plurality of rotating bodies, respectively driving the plurality of rotating bodies, or dividing the plurality of rotating bodies into a plurality of groups. A plurality of detecting means for detecting the rotation phases of the plurality of rotating bodies or the plurality of rotating body groups, respectively, and the plurality of rotating bodies or the plurality of rotating body groups based on the detection results of the plurality of detecting means. And a color image forming apparatus that suppresses color misregistration by adjusting the rotational phase difference.
The adjusting means uses the rotational phase of the first rotating body or the rotating body group including the rotating body for image formation as a reference so that the rotational phase of the rotating body or the rotating body group matches the rotational phase. A color image forming apparatus for adjusting a phase difference. The color image forming apparatus according to claim 1.
In the case where image formation is performed using two or more and less than all of the rotating bodies, the adjusting means rotates the rotation body on the basis of the rotation phase of the rotating body that performs image formation first or the rotating body group that includes the rotating bodies. A color image forming apparatus, characterized in that a rotational phase difference is adjusted so that a rotational phase of another rotating body or a group of rotating bodies matches a phase. The color image forming apparatus according to claim 1 or 2,
A color image forming apparatus that starts image formation of the reference rotating body or a group of rotating bodies including the rotating body while adjusting the rotational phase difference. A plurality of rotating bodies each carrying an image of each color; and a plurality of motors for driving the plurality of rotating bodies, respectively driving the plurality of rotating bodies, or dividing the plurality of rotating bodies into a plurality of groups. A plurality of detecting means for detecting the rotation phases of the plurality of rotating bodies or the plurality of rotating body groups, respectively, and the plurality of rotating bodies or the plurality of rotating body groups based on the detection results of the plurality of detecting means. And a color image forming apparatus that suppresses color misregistration by adjusting the rotational phase difference.
The adjusting means rotates on the basis of the rotational phase of the rotating body or the rotating body group having the element that takes the longest time for phase adjustment so that the rotating phase of the rotating body or the rotating body group matches the rotational phase. A color image forming apparatus characterized by adjusting a phase difference. The color image forming apparatus according to claim 4.
The color image forming apparatus according to claim 1, wherein the element is a load torque to a motor that drives the rotating body or the rotating body group. The color image forming apparatus according to claim 4.
The color image forming apparatus according to claim 1, wherein the element is a load inertia for a motor that drives the rotating body or the group of rotating bodies. The color image forming apparatus according to claim 4.
The color image forming apparatus according to claim 1, wherein the element is a transmission delay from a motor that drives the rotating body or the rotating body group to the rotating body or the rotating body group.

Images