JP5162815B2 - Image forming apparatus - Google Patents

Description

  In the present invention, toner images of different colors are formed on a plurality of photoconductors, each of the toner images is transferred onto an intermediate transfer member, and the toner image on the intermediate transfer member is transferred to a recording material. The present invention also relates to an image forming apparatus that obtains a recorded image by transferring each toner image formed on each photoconductor to a recording material carried and conveyed by a recording material conveyance body.

  An image forming apparatus of the above type configured as an electronic copying machine, a printer, a facsimile, or a complex machine thereof has been conventionally known. In this type of image forming apparatus, if each photoconductor or a drive gear for driving the photoconductor is decentered, a color shift occurs in a recorded image formed on the recording material, and the image quality deteriorates. In view of this, a technique for adjusting the phase of the photoconductors so that the phases of the plurality of photoconductors have a predetermined relationship and preventing color misregistration of a recorded image formed on the recording material has been conventionally employed (for example, Patent Document 1 or 2). At this time, it is also conventionally known that the surface linear velocity of the photoconductor is changed with respect to the surface linear velocity during the image forming operation so that the phases of the plurality of photoconductors have a predetermined relationship. When this configuration is adopted, the phase of the photoconductor can be adjusted in a short time. However, if the surface linear velocity of the photoconductor is changed during phase adjustment of the photoconductor, the difference in the surface linear velocity between the photoconductor and the intermediate transfer member or recording material conveyance body in contact with the photoconductor increases. Is rubbed with a large difference in linear velocity, so that it is inevitable that the wear of the photosensitive member, the intermediate transfer member or the recording material conveying member is accelerated and the life thereof is reduced.

JP 2000-187428 A JP 2004-233952 A

  An object of the present invention is to provide an image forming apparatus that can eliminate or alleviate the above-mentioned conventional defects.

In order to achieve the above object, the present invention provides a color photoconductor on which a chromatic toner image is formed, a black photoconductor on which a black toner image is formed, and a toner image formed on the photoconductor. An intermediate transfer member to be transferred, all the photosensitive members and the intermediate transfer member are brought into contact with each other, and the toner image formed on each of the photosensitive members is transferred onto the intermediate transfer member to be transferred to the intermediate transfer member. A color mode in which the transferred toner image is transferred to a recording material to obtain a recorded image, the color photosensitive member and the intermediate transfer member are separated, and the black photosensitive member and the intermediate transfer member are contacted. A monochrome mode in which a black toner image formed on the black photosensitive member is transferred to an intermediate transfer member, and the black toner image transferred to the intermediate transfer member is transferred to a recording material to obtain a recorded image; And the surface of the photoconductor during phase adjustment of the photoconductor In the image forming apparatus that controls the phase of the photoconductor to change to a predetermined relationship by changing the speed, the black photoconductor and the intermediate transfer body are brought into contact with each other at the time of phase adjustment of the photoconductor. The photosensitive member for color and the intermediate transfer member are separated from each other, the surface linear velocity of the photosensitive member for black is made lower than the surface linear velocity at the time of image forming operation, and the surface linear velocity of the photosensitive member for color is reduced during image forming operation. The surface linear velocity of the intermediate transfer member is changed so as to be substantially equal to the surface linear velocity of the black photosensitive member in contact with the intermediate transfer member, or the black The surface linear velocity of the photosensitive member is increased from the surface linear velocity during the image forming operation, the surface linear velocity of the color photosensitive member is decreased from the surface linear velocity during the image forming operation, and the surface linear velocity of the intermediate transfer member Approximately equal to the surface linear velocity of the black photosensitive member in contact with the intermediate transfer member. By changing the Kunar so, the phase of all the photosensitive body is proposed an image forming apparatus and controls so as to have a predetermined relationship (claim 1).

In order to achieve the above object, the present invention carries a color photosensitive member on which a chromatic toner image is formed, a black photosensitive member on which a black toner image is formed, and a recording material. Each of the photosensitive members is in contact with the recording material conveyance body via the recording material carried and conveyed by the recording material conveyance body. The color mode in which the toner image is transferred onto the recording material and transferred to obtain a recorded image, the color photoconductor and the recording material transport body are separated from each other, and are carried and transported by the recording material transport body. The black photosensitive member and the recording material conveying member are brought into contact with each other through a recording material, and a black toner image formed on the black photosensitive member is transferred to the recording material to obtain a recorded image. Monochrome mode can be selected, and the surface of the photoconductor is adjusted during phase adjustment of the photoconductor In the image forming apparatus that controls the phase of the photosensitive member to change to a predetermined relationship by changing the speed, the black photosensitive member and the recording material conveying member are brought into contact with each other when the phase of the photosensitive member is adjusted. The color photosensitive member and the recording material conveying member are separated from each other, and the surface linear velocity of the black photosensitive member is made lower than the surface linear velocity during the image forming operation, and the surface linear velocity of the color photosensitive member is formed. Increase the surface linear velocity during operation and change the surface linear velocity of the recording material transport member so as to be approximately equal to the surface linear velocity of the black photosensitive member in contact with the recording material transport member, Alternatively, the surface linear velocity of the black photoconductor is higher than the surface linear velocity during the image forming operation, the surface linear velocity of the color photoconductor is lower than the surface linear velocity during the image forming operation, and the recording material is conveyed. The surface speed of the black photosensitive member in contact with the recording material conveying member Fast and varied to substantially equal the phase of all the photosensitive body is proposed an image forming apparatus and controls so as to have a predetermined relationship (claim 2).

  The image forming apparatus according to claim 1 or 2, further comprising: a drive gear fixed to each photoconductor; and first and second drive motors, wherein the output gear of the first drive motor is Meshing with a drive gear fixed to the black photoconductor, and an output gear of the second drive motor meshing with a drive gear fixed to each of the adjacent first and second color photoconductors, An intermediate gear meshes with the drive gear fixed to the second color photoconductor and the drive gear fixed to the third color photoconductor located adjacent to the second color photoconductor. (Claim 3).

  The image forming apparatus according to claim 3, further comprising: a first sensor that detects a phase of a driving gear fixed to the black photosensitive member; and a driving gear fixed to the color photosensitive member. And a second sensor for detecting the phase, and the first and second sensors can detect the phase difference between the black photosensitive member and the color photosensitive member. 4).

  Furthermore, in the image forming apparatus according to claim 1, with respect to the moving direction of the intermediate transfer member, the black photosensitive member is located on the most downstream side, and the color photosensitive member is located on the upstream side thereof. (Claim 5).

3. The image forming apparatus according to claim 2, wherein the black photoconductor is located on the most downstream side and the color photoconductor is located on the upstream side in the moving direction of the recording material conveyance body. (Claim 6).
Further, in the image forming apparatus according to claim 1, it is advantageous that the distances between the transfer positions at which the toner images are transferred from the respective photosensitive members to the intermediate transfer member are all set equal to each other (claim 7).
In the image forming apparatus according to claim 2, it is advantageous that the distances between the transfer positions at which the toner images are transferred from the respective photosensitive members to the recording material carried on the recording material conveyance body are all set equal. (Claim 8).

  According to the present invention, it is possible to prevent the photosensitive member, the intermediate transfer member, or the recording material transport member from being worn out at an early stage, and to extend its life.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a schematic view showing an example of an image forming apparatus. The image forming apparatus shown here has a plurality of photoreceptors 3Y, 3C, 3M that are rotatably supported with respect to a main body frame (not shown). , 3BK. The photoreceptor shown here is formed in a drum shape, and a yellow toner image, a cyan toner image, a magenta toner image, and a black toner image are formed on each of the photoreceptors 3Y, 3C, 3M, and 3BK. An intermediate transfer member 4 composed of an endless belt is disposed opposite to the photosensitive members 3Y to 3BK, and the intermediate transfer member 4 is wound around a plurality of support rollers 5, 6, 7, and 8 to thereby form a plurality of photosensitive members. It is rotationally driven in the direction of arrow A while contacting the surfaces of the bodies 3Y to 3BK. In the following description, the photoreceptors 3Y, 3C, and 3M on which the chromatic toner images of the yellow toner image, the cyan toner image, and the magenta toner image are formed are referred to as color photoreceptors as necessary. The photoreceptor 3BK on which the toner image is formed is referred to as a black photoreceptor.

  Since the operation of forming a toner image on each of the photoconductors 3Y, 3C, 3M, and 3BK is substantially the same, only the configuration for forming a toner image on the photoconductor 3Y will be described here. During the image forming operation, the photoreceptor 3Y is rotationally driven in the clockwise direction in FIG. 1 at a surface linear velocity substantially equal to the surface linear velocity of the intermediate transfer member 4. At this time, the surface of the photoreceptor is charged to a predetermined polarity by the charging roller 9. The Next, the charged surface is irradiated with a light-modulated laser beam LB emitted from the laser writing unit 10. As a result, an electrostatic latent image is formed on the photoreceptor 3Y, and the electrostatic latent image is visualized as a yellow toner image by the developing device 11. The developing device 11 shown here has a developing roller 12 that is rotationally driven, and the electrostatic latent image is visualized by the developer carried on the developing roller 12.

  A primary transfer roller 13 is disposed at a position substantially opposite to the photoreceptor 3Y with the intermediate transfer body 4 interposed therebetween, and the yellow toner image on the photoreceptor 3Y is transferred to the intermediate transfer body 4 by the action of the transfer roller 13. The residual transfer toner that is not transferred to the intermediate transfer body 4 and remains on the photoreceptor 3 </ b> Y is removed by the cleaning device 14. The cleaning device 14 shown in FIG. 1 has a cleaning blade 15 that presses against the surface of the photoreceptor 3Y and scrapes off transfer residual toner.

  In exactly the same manner, a cyan toner image, a magenta toner image, and a black toner image are formed on the other photoconductors 3C, 3M, and 3BK, and these toner images are transferred onto the intermediate transfer body 4 on which the yellow toner image is transferred. The images are transferred one after the other.

  On the other hand, a recording material P made of, for example, transfer paper or a resin sheet is fed between the intermediate transfer body 4 and the secondary transfer roller 16 as shown by an arrow B from a paper feeder (not shown). At this time, the superimposed toner image on the intermediate transfer body 4 is transferred to the recording material P by the action of the secondary transfer roller 16. The recording material P carrying the four color toner images in this way passes through a fixing device (not shown). At this time, the toner image on the recording material P is fixed to the recording material P by the action of heat and pressure. Is done. The recording material that has passed through the fixing device is discharged to a paper discharge tray (not shown). Further, the transfer residual toner adhering to the intermediate transfer body 4 after the superimposed toner image is transferred to the recording material P is removed by the cleaning device 17. In this way, a full color image is formed on the recording material P.

As described above, the mode for forming a full-color image on the recording material is the color mode. However, in addition to this color mode, the illustrated image forming apparatus has a monochrome mode for forming a black monochrome image on the recording material. You can also choose. In the monochrome mode, the intermediate transfer member 4 is separated from the color photoconductors 3Y, 3C, and 3M on which the chromatic toner images are formed, and contacts only with the black photoconductor 3BK on which the black toner images are formed. . The color photoconductors 3Y, 3C, 3M other than the black photoconductor 3BK do not rotate, and only the black photoconductor 3BK is driven to rotate, and on the photoconductor 3BK, exactly as described above. As a result, a black toner image is formed. This black toner image is transferred onto the recording material sent from the paper feeding device, and this recording material also passes through the fixing device. At this time, the black toner image is fixed on the recording material, and the recording material is discharged. It is discharged to the tray.
As described above, the image forming apparatus of this example includes the color photoconductors 3Y, 3C, and 3M on which chromatic toner images are formed, the black photoconductor 3BK on which black toner images are formed, and these And an intermediate transfer body 4 to which toner images formed on the photoconductors 3Y, 3C, 3M, and 3BK are transferred. All the photoconductors 3Y, 3C, 3M, and 3BK and the intermediate transfer body 4 are brought into contact with each other. The toner images formed on the respective photoreceptors 3Y, 3C, 3M, and 3BK are transferred to the intermediate transfer member 4 so as to be transferred, and the superimposed toner images transferred to the intermediate transfer member 4 are transferred to the recording material P to be recorded images. The color photoconductors 3Y, 3C, 3M and the intermediate transfer body 4 are separated from each other, and the black photoconductor 3BK and the intermediate transfer body 4 are brought into contact with each other, thereby the black photoconductor The black toner image formed on 3BK is transferred to the intermediate transfer body 4, and the intermediate transfer body It has become a monochrome mode can be selected to obtain a recorded image is transferred to the recording material P black toner image transferred to.

FIG. 1 shows a state when the image forming apparatus is viewed from the front side, and FIG. 2 shows a state when the image forming apparatus is viewed from the back side. As shown in FIG. 2, to each of the photoconductors 3Y to 3BK, drive gears 32Y, 32C, 32M, and 32BK arranged concentrically with the photoconductors are detachably fixedly connected, and these drive gears 32Y. Thru 32BK are rotatably supported by the main body frame of the image forming apparatus. A first drive motor 35 is supported on the main body frame, and an output gear 36 fixed to the output shaft meshes with the drive gear 32BK. The rotation of the drive motor 35 is transmitted to the photoconductor 3BK via the output gear 36 and the drive gear 32BK, whereby the photoconductor 3BK is rotationally driven in the clockwise direction in FIG. In addition, as shown in FIG. 2, a second drive motor 135 is fixedly supported on the main body frame, and an output gear 136 fixed to the output shaft of the main body frame drives the photoreceptor 3C on which a cyan toner image is formed. The gear 32C and the drive gear 32M for the photoconductor 3M on which a magenta toner image is formed mesh with each other. Further, an intermediate gear 53 shown in FIG. 2 is rotatably supported by the main body frame, and the intermediate gear 53 forms a drive gear 32C for the photoreceptor 3C on which a cyan toner image is formed and a yellow toner image. Meshed with the driving gear 32Y for the photoreceptor 3Y. The rotation of the drive motor 135 is transmitted to the drive gears 32C and 32M via the output gear 136, and the drive gears 32C and 32M are rotated in the counterclockwise direction in FIG. This is transmitted to the drive gear 32Y via the intermediate gear 53, and this drive gear 32Y is driven to rotate counterclockwise in FIG. The rotations of the drive gears 32Y, 32C, and 32M are transmitted to the photoreceptors 3Y, 3C, and 3M, and thereby the photoreceptors 3Y, 3C, and 3M are rotationally driven in the clockwise direction in FIG.
As shown in FIG. 1, in the image forming apparatus of this example, the black photosensitive member 3BK is located on the most downstream side in the moving direction of the intermediate transfer member 4, and the color photosensitive member is located upstream of the black photosensitive member 3BK. 3M, 3C and 3Y are located respectively. Here, if necessary, the three low color photosensitive members 3M, 3C, and 3Y located adjacent to the black photosensitive member 3BK are referred to as first to third color photosensitive members, respectively. As described above, the image forming apparatus of this example includes the drive gears 32Y, 32C, 32M, and 32BK that are fixed to the photosensitive members 3Y, 3C, 3M, and 3BK, and the first and second drive motors 35 and 135. The output gear 36 of the first drive motor 35 meshes with the drive gear 32BK fixed to the black photosensitive member 3BK, and the output gear 136 of the second drive motor 135 is adjacent to the first and second drive gears 32BK. The driving gears 32M and 32C fixed to the second color photoconductors 3M and 3C respectively mesh with the driving gears 32C and 32C fixed to the second color photoconductor 3C and the second color photoconductors. Next to body 3C The third photosensitive element 3Y in a fixed drive gear 32Y for color to the intermediate gear 53 is engaged.

  Here, the drive gears 32Y, 32C, 32M, and 32BK described above have the same shape as the same radius, and are made of, for example, resin or metal. At that time, especially when these gears are made of resin, it is inevitable that the gears are slightly decentered. As a result, the toner images of the respective colors are transferred on the recording material P while being slightly displaced. As a result, color shift may occur in the completed full-color image. Therefore, in the image forming apparatus of this example, as in the prior art, the plurality of photoconductors 3Y to 3BK are positioned with a predetermined phase relationship together with the drive gears 32Y to 32BK fixedly connected to the photoconductors. .

  FIG. 3 is a diagram for explaining an example thereof. FIG. 3 is a view as seen from the front side of the image forming apparatus as in FIG. Here, it is assumed that the distance between the transfer positions at which the toner images are transferred from the photoreceptors 3Y, 3C, 3M, 3BK to the intermediate transfer body 4 is L. The distances L between the transfer positions at which the toner images are transferred from the photoreceptors 3Y, 3C, 3M, 3BK to the intermediate transfer body 4 are all set equal. A reference position of the outer peripheral surface in the circumferential direction of each of the photoconductors 3Y to 3BK and a reference position in the circumferential direction of each of the drive gears 32Y, 32C, 32M, and 32BK corresponding thereto are represented by X. Further, it is assumed that the drive gears 32Y, 32C, 32M, and 32BK are resin gears having the same form and molded by the same mold.

  In the state shown in FIG. 3, the reference position X of the photoreceptor 3 </ b> Y where the yellow toner image is formed is at the transfer position, and the yellow toner image on the photoreceptor 3 </ b> Y is transferred to the intermediate transfer body 4. At this time, the reference position X of the photoconductor 3C adjacent to the photoconductor 3Y is located at a position L away from the transfer position on the upstream side in the rotation direction of the photoconductor 3C, and similarly the reference position X of the photoconductor 3M. Is separated from the transfer position by 2 × L, and similarly, the photoreceptor 3BK is separated by 3 × L from the transfer position. The reference positions X of the drive gears 32Y, 32C, 32M, and 32BK are determined so as to have such a positional relationship. Thereby, even if each gear 32Y thru | or 32BK is slightly decentered, it can prevent that a color shift generate | occur | produces in the color image formed on the recording material.

  As described above, the mounting angle positions of the photoconductors 3Y to 2BK and the drive gears 32Y, 32C, 32M, and 32BK fixedly connected to the photoconductors are set so as not to cause color misregistration in the completed full-color image. However, there is a possibility that the phase is slightly out of phase during the image forming operation. When the monochrome mode is executed, only the photoreceptor 3BK on which the black toner image is formed rotates, so that the phases of the photoreceptor 3BK and the photoreceptors 3Y, 3C, and 3M on which the chromatic toner images are formed are completely. It becomes a crazy state.

  Therefore, in the image forming apparatus of this example, for example, the phase of the plurality of photoconductors 3Y to 3BK is adjusted before starting the image forming operation, and the surface lines of the photoconductors 3Y to 3BK are adjusted during the phase adjustment. The speed is changed with respect to the surface linear speed during the image forming operation, and the phases of the plurality of photoconductors 3Y to 3BK are controlled to have a predetermined relationship. Specific examples thereof are as follows.

  First, the drive gears 32Y to 32BK respectively connected to the photoreceptors 3Y to 3BK will be referred to as yellow gear 32Y, cyan gear 32C, magenta gear 32M and black gear 32BK, respectively, as required. As shown, first and second reference protrusions 54BK and 54M are fixed to the black gear 32BK and the magenta gear 32M, respectively, and the first and the second reference protrusions 54BK and 54M are detected on the main body frame, respectively. Second sensors 55BK and 55M are provided. These sensors 55BK and 55M are photosensors having a light emitting element and a light receiving element. At the time of phase adjustment, both the first and second drive motors 35 and 135 are operated, and after the operations are stabilized, the first and second reference protrusions 54BK and 54M are respectively connected to the first and second sensors 55BK and 55M. The timing for shielding between the light emitting element and the light receiving element is detected. Thereby, the relative phase difference between the black gear 32BK and the magenta gear 32M is detected. Further, based on the detection result, the speeds of the first and second drive motors 35 and 135 are increased or decreased with respect to the speed during the image forming operation so that the phases of the black gear 32BK and the magenta gear 32M have a predetermined relationship. The surface linear velocity of the photoreceptors 3Y to 3BK is changed. The phases of the drive gears 32Y, 32C, and 32M for the photoreceptors 3Y, 3C, and 3M on which the chromatic toner images are formed are adjusted in advance so as to have a predetermined relationship when the photoreceptors and the gears are assembled. Therefore, the phases of all the photoreceptors 3Y to 3BK can be set to a predetermined relationship by the above-described phase adjustment. As described above, the image forming apparatus of the present example includes the first sensor 55BK that detects the phase of the drive gear 32BK that is fixed to the black photoconductor 3BK, and the drive gear 32M that is fixed to the color photoconductor 3M. And a second sensor 55M for detecting the phase of the black, and the first and second sensors 55BK and 55M detect the phase difference between the black photoconductor 3BK and the color photoconductors 3M, 3C and 3Y. It is configured to do.

  Here, also during phase adjustment of the plurality of photoconductors 3Y to 3BK, the intermediate transfer body 4 is driven in the direction of arrow A at the same speed as during the image forming operation. Accordingly, at this time, if each of the photoconductors 3Y to 3BK and the intermediate transfer body 4 remain in contact, the photoconductor and the intermediate transfer body are rubbed at a high linear velocity, and their wear is promoted, and the lifetime thereof is increased. Decreases.

  Therefore, in the image forming apparatus of the present example, before phase difference between the photosensitive members 3Y to 3BK and the intermediate transfer member 4 occurs during phase adjustment of a plurality of photosensitive members, a solenoid or motor (not shown) As shown in FIG. 4, the photoconductors 3Y to 3BK and the intermediate transfer body 4 are separated by such means. Thereby, at the time of phase adjustment, it is possible to prevent friction due to slip between the photoconductors 3Y to 3BK and the intermediate transfer body 4, and to extend the lifetime of both.

FIG. 5 shows an example of a flowchart at the time of the phase adjustment described above. In FIG. 5, when phase adjustment is started (S ₁ ), the relative phase difference between the black gear 32BK and the magenta gear 32M is detected (S ₂ ), and whether the phases of the gears 32BK and 32M are in a predetermined relationship or not. Is checked (S ₃ ). When these phases are not in a predetermined relationship, all the photosensitive drum 3Y that has been in contact until then, 3C, 3M, to separate the 3BK and the intermediate transfer member 4 (S _4). Then, the black gear 32BK is checked whether precedes the magenta gear 32M (S _5), when the black gear 32BK is leading, a second drive with decelerating the first drive motor 35 The motor 135 is accelerated (S ₆ ). Conversely, when the magenta gear 32M is ahead of the black gear 32BK has a first driving motor 35 is accelerated, thereby decelerating the second drive motor 135 _(S 7).

On the other hand, when the phases of the black gear 32BK and the magenta gear 32M are in a predetermined relationship, if the photosensitive member and the intermediate transfer member have been separated so far, they are brought into contact with each other (S ₈ ) to adjust the phase. Exit.

In the above-described example, all the photoconductors 3Y to 3BK and the intermediate transfer body 4 are separated from each other at the time of phase adjustment of the plurality of photoconductors. However, a part of the photoconductors and the intermediate transfer body 4 are separated from each other. You can also In this case, the surface linear velocity of the photoconductor in contact with the intermediate transfer member 4 is not changed, and only the surface linear velocity of the photoconductor separated from the intermediate transfer member 4 is changed, and a plurality of photoconductors are changed. By controlling the phases of 3Y to 3BK to have a predetermined relationship, it is possible to adjust the phase of the photoconductor while suppressing wear of the photoconductor and the intermediate transfer member. FIG. 6 shows a case in which only the color photoconductors 3Y, 3C, and 3M are separated from the intermediate transfer body 4 and the black photoconductor 3BK is kept in contact with the intermediate transfer body 4 when the phase of the photoconductor is adjusted. It is a flowchart which shows operation | movement. The difference from the flowchart shown in FIG. 5 is as follows. That is, after the phases of the black gear 32BK and the magenta gear 32M are not in a predetermined relationship, the photosensitive members 3Y, 3C, 3M and the intermediate transfer member 4 are separated from each other by means such as a solenoid or a motor (S ₄ ). , when the black gear 32BK is ahead of the magenta gear 32M, is accelerated to the second driving motor _{135 (S 5, S 6)} , magenta gear 32M is ahead of the black gear 32BK conversely If so, the second drive motor 135 is decelerated (S ₅ , S ₆ ). Thereby, it is possible to prevent the friction caused by the slip between the photosensitive member and the intermediate transfer member . In this example, when the phase adjustment of the photoreceptor, so to increase the deceleration photoconductor 3Y for color, 3C, 3M only, but the advantage of reducing the manufacturing cost of the image forming apparatus is obtained, the photosensitive member 3BK also acceleration and deceleration Compared to the above-described example, the time required for phase adjustment becomes longer, which is disadvantageous for shortening the first print time.

Further, during phase adjustment of the plurality of photoconductors 3Y to 3BK, a part of the photoconductors and the intermediate transfer body 4 are separated, and the surface linear velocity of the photoconductor that is in contact with the intermediate transfer body 4 and the intermediate transfer body 4 are separated. And the surface linear velocity of the intermediate transfer member 4 is changed to be substantially equal to the surface linear velocity of the photosensitive member in contact with the intermediate transfer member 4. In this way, the phases of the plurality of photoconductors can be controlled to have a predetermined relationship. FIG. 7 is a flowchart showing an example. Also in this example, only the color photoconductors 3Y, 3C, and 3M are separated from the intermediate transfer body 4 during the phase adjustment of the photoconductor, and the black photoconductor 3BK is kept in contact with the intermediate transfer body 4. . The difference from the flowchart shown in FIG. 6 is that when the black gear 32BK is ahead of the magenta gear 32M, the first drive motor 35 is decelerated to reduce the surface linear velocity of the black photoreceptor 3BK. At the same time, the intermediate transfer drive motor that drives the intermediate transfer body 4 is also decelerated so that the surface linear velocity of the intermediate transfer body 4 is substantially equal to the surface linear velocity of the black photoreceptor 3BK, and the second drive motor. When the speed of 135 is increased (S ₅ , S ₆ ) and the magenta gear 32M is ahead of the black gear 32BK, both the first drive motor 35 and the intermediate transfer drive motor are accelerated to increase the speed for black. The surface linear velocity of the photoreceptor 3BK and the surface linear velocity of the intermediate transfer member 4 are made substantially the same, and the second drive motor 135 is decelerated (S ₅ , S ₇ ). As described above, at the time of phase adjustment of the photoconductor, the black photoconductor 3BK and the intermediate transfer body 4 are brought into contact with each other, and the color photoconductors 3Y, 3C, 3M and the intermediate transfer body 4 are separated from each other to be used for black. The surface linear velocity of the photoconductor 3BK is lower than the surface linear velocity during the image forming operation, the surface linear velocity of the color photoconductors 3Y, 3C, and 3M is increased above the surface linear velocity during the image forming operation, and The surface linear velocity of the intermediate transfer member 4 is changed so as to be substantially equal to the surface linear velocity of the black photosensitive member 3BK in contact with the intermediate transfer member 4, or the surface linear velocity of the black photosensitive member. Is made higher than the surface linear velocity during the image forming operation, the surface linear velocity of the color photoconductors 3Y, 3C, and 3M is made lower than the surface linear velocity during the image forming operation, and the surface linear velocity of the intermediate transfer member 4 is increased. The surface linear velocity and the surface speed of the black photoconductor 3BK in contact with the intermediate transfer member 4 Varied to be equal, all the photosensitive bodies 3Y, 3C, 3M, phase 3BK is to control so as to have a predetermined relationship. According to this configuration, due to the difference in surface linear velocity between the photoconductor and the intermediate transfer body, they can be prevented from being worn at an early stage, and all the photoconductors 3Y to 3BK are accelerated and decelerated. Adjustments can be made and the first print time can be shortened.

  In the specific example described above, the photosensitive member is rotationally driven by the first drive motor 35 and the second drive motor 135, but the image forming apparatus is of a type in which each photosensitive member is rotationally driven by its dedicated drive motor. Also, the present invention can be applied.

Further, as shown in FIG. 8, a color photoreceptor 3Y, 3C, 3M on which a chromatic toner image is formed, a black photoreceptor 3BK on which a black toner image is formed, and a recording material P are carried. The above-described configurations can also be employed in an image forming apparatus that includes the recording material transport member 104 that transports the recording material. That is, this image forming apparatus also has all the photoconductors 3Y, 3C, 3M, and 3BK and the recording material conveyance body 104 in contact with each other through the recording material P carried and conveyed by the recording material conveyance body 104. A color mode in which the toner images formed on the respective photoreceptors 3Y, 3C, 3M, and 3BK are transferred onto the recording material P so as to obtain a recorded image; and the color photoreceptors 3Y, 3C, 3M, and the recording material The black photosensitive member 3BK and the recording material conveyance body 104 are brought into contact with each other via the recording material P carried and conveyed by the recording material conveyance body 104, while being separated from the conveyance body 104. The monochrome mode in which the black toner image formed on the photosensitive member 3BK is transferred to the recording material P to obtain a recorded image can be selected, and the surface linear velocity of the photosensitive member is changed during phase adjustment of a plurality of photosensitive members. The phases of the plurality of photoconductors 3Y to 3BK are predetermined. Controlled to be related, during the phase adjustment of the plurality of photoreceptor may be provided with means for separating the photosensitive drum 3Y to 3BK and the recording material conveying member 104.
At that time, all the photoconductors 3Y to 3BK and the recording material transport body 104 can be separated from each other at the time of phase adjustment of the plurality of photoconductors 3Y to 3BK, and at the time of phase adjustment of the plurality of photoconductors 3Y to 3BK. A part of the photosensitive member and the recording material transport member 104 are separated, and the surface linear velocity of the photosensitive member in contact with the recording material transport member 104 is not changed, and the photosensitive member is separated from the recording material transport member 104. It is also possible to control so that the phases of the plurality of photoconductors 3Y to 3BK have a predetermined relationship by changing only the surface linear velocity .
Further, at the time of phase adjustment of the plurality of photoconductors 3Y to 3BK, a part of the photoconductors and the recording material conveyance body 104 are separated from each other, and the surface linear velocity of the photoconductor that is in contact with the recording material conveyance body 104 and the recording material The surface linear velocity of the photoconductor separated from the conveyance body 104 is changed together, and the surface linear velocity of the recording material conveyance body 104 is substantially equal to the surface linear velocity of the photoconductor in contact with the recording material conveyance body 104. It is also possible to control so that the phases of the plurality of photoconductors have a predetermined relationship by changing them to be equal. That is, at the time of phase adjustment of the photoconductor, the black photoconductor 3BK and the recording material transport body 104 are brought into contact with each other, and the color photoconductors 3Y, 3C, 3M and the recording material transport body 104 are separated from each other . The surface linear velocity of the photoconductor 3BK is lower than the surface linear velocity during the image forming operation, the surface linear velocity of the color photoconductors 3Y, 3C, and 3M is increased above the surface linear velocity during the image forming operation, and The surface linear velocity of the recording material conveyance body 104 is changed so as to be substantially equal to the surface linear velocity of the black photosensitive member 3BK in contact with the recording material conveyance member 104, or the surface of the black photosensitive member The linear velocity is increased from the surface linear velocity during the image forming operation, the surface linear velocity of the color photoconductors 3Y, 3C, and 3M is decreased from the surface linear velocity during the image forming operation, and the recording material conveying member 104 The surface linear velocity is in contact with the recording material carrier 104. Varied so as to be substantially equal to the surface linear velocity of the photoconductor 3BK for black, all the photosensitive bodies 3Y, 3C, 3M, phase 3BK is to control so as to have a predetermined relationship. In the image forming apparatus shown in FIG. 8 as well, the black photoconductor 3BK is located on the most downstream side in the moving direction of the recording material conveyance body 104, and the color photoconductors 3M, 3C,. 3Y is located, and the distances between the transfer positions at which the toner images are transferred from the respective photosensitive members 3Y, 3C, 3M, 3BK to the recording material P carried on the recording material conveyance body 104 are set to be equal. In FIG. 8, parts corresponding to the parts shown in FIG. 1 are denoted by the same reference numerals as those in FIG.

1 is a schematic diagram of an image forming apparatus. FIG. 3 is a diagram illustrating a state where a photoconductor and a drive gear are viewed from the back side of the image forming apparatus. It is a figure explaining the phase relationship of a some photoconductor and its drive gear. FIG. 5 is a schematic diagram illustrating a state where a plurality of photosensitive members and an intermediate transfer member are separated from each other during phase adjustment of the photosensitive member. 6 is a flowchart showing an example of operation during phase adjustment of the photosensitive member. 6 is a flowchart showing another example of operation during phase adjustment of the photoreceptor. 10 is a flowchart showing still another operation example during phase adjustment of the photosensitive member. It is the schematic which shows the example of the image forming apparatus of another form.

Explanation of symbols

3Y, 3C, 3M, 3BK Photosensitive member 4 Intermediate transfer member 32Y, 32C, 32M, 32BK Drive gear 35, 135 Drive motor 36, 136 Output gear 53 Intermediate gear 55BK, 55M Sensor 104 Recording material conveyance body L Distance P Recording material

Claims (8)

A color photoreceptor on which a chromatic toner image is formed; a black photoreceptor on which a black toner image is formed; and an intermediate transfer body onto which the toner image formed on the photoreceptor is transferred; All the photoconductors and the intermediate transfer member are brought into contact with each other, and the toner images formed on the respective photoconductors are transferred onto the intermediate transfer member, and the superimposed toner images transferred onto the intermediate transfer member are transferred onto the recording material. A color mode for obtaining a recorded image, and separating the color photoconductor from the intermediate transfer member and bringing the black photoconductor and the intermediate transfer member into contact with each other so that the black photoconductor It is possible to select a monochrome mode in which the formed black toner image is transferred to an intermediate transfer body, and the black toner image transferred to the intermediate transfer body is transferred to a recording material to obtain a recorded image. During phase adjustment, the surface linear velocity of the photoconductor is changed to change the phase of the photoconductor. In the image forming apparatus is controlled to be a predetermined relationship,
When the phase of the photoconductor is adjusted, the black photoconductor and the intermediate transfer body are brought into contact with each other, and the color photoconductor and the intermediate transfer body are separated from each other, and the surface linear velocity of the black photoconductor is determined as an image forming operation. The surface linear velocity of the color photoconductor is increased from the surface linear velocity of the image forming operation, and the surface linear velocity of the intermediate transfer member is brought into contact with the intermediate transfer member. The surface linear velocity of the black photosensitive member is changed to be approximately equal to the surface linear velocity of the black photosensitive member, or the surface linear velocity of the black photosensitive member is made higher than the surface linear velocity at the time of image forming operation. The surface linear velocity is made lower than the surface linear velocity at the time of image forming operation, and the surface linear velocity of the intermediate transfer member is made substantially equal to the surface linear velocity of the black photosensitive member in contact with the intermediate transfer member. It is characterized in that it is controlled so that the phases of all the photoconductors have a predetermined relationship. That the image forming apparatus. A color photosensitive member on which a chromatic toner image is formed; a black photosensitive member on which a black toner image is formed; and a recording material conveying member that carries and conveys the recording material. All the photoconductors and the recording material conveyance body are brought into contact with each other through the recording material carried and conveyed by the body, and the toner images formed on the respective photoconductors are transferred onto the recording material and transferred. The black photoconductor through a color mode for obtaining an image, the color photoconductor and the recording material conveyance body being separated from each other, and the recording material carried and conveyed by the recording material conveyance body And a monochrome mode in which a black toner image formed on the black photosensitive member is transferred to a recording material to obtain a recorded image by contacting the recording material conveying member with the recording material conveying member; When the phase of the photoconductor is adjusted, the surface linear velocity of the photoconductor is changed so that the phase of the photoconductor is predetermined. In the image forming apparatus is controlled to be a relationship,
At the time of phase adjustment of the photoconductor, the black photoconductor and the recording material conveyance body are brought into contact with each other, and the color photoconductor and the recording material conveyance body are separated from each other so that the surface linear velocity of the black photoconductor is determined as an image. In addition to lowering the surface linear velocity during the forming operation, increasing the surface linear velocity of the color photoconductor than the surface linear velocity during the image forming operation, and increasing the surface linear velocity of the recording material transport body to the recording material transport body The surface linear velocity of the black photosensitive member in contact with the surface is changed to be approximately equal to the surface linear velocity of the black photosensitive member, or the surface linear velocity of the black photosensitive member is made higher than the surface linear velocity at the time of image forming operation. The surface linear velocity of the photosensitive member for black is lower than the surface linear velocity at the time of the image forming operation, and the surface linear velocity of the recording material transport member is set to the surface linear velocity of the black photosensitive member that is in contact with the recording material transport member. So that the phases of all the photoconductors are in a predetermined relationship. An image forming apparatus comprising and. A drive gear fixed to each photoconductor, and first and second drive motors, and an output gear of the first drive motor meshes with a drive gear fixed to the black photoconductor, The output gear of the second drive motor meshes with the drive gear fixed to the adjacent first and second color photoconductors, and the drive gear fixed to the second color photoconductor and the second gear. 3. The image forming apparatus according to claim 1, wherein an intermediate gear meshes with a drive gear fixed to the third color photoconductor positioned adjacent to the second color photoconductor. A first sensor for detecting a phase of a driving gear fixed to the black photoconductor, and a second sensor for detecting a phase of a driving gear fixed to the color photoconductor, 4. The image forming apparatus according to claim 3, wherein the first and second sensors detect a phase difference between the black photoconductor and the color photoconductor. 2. The image forming apparatus according to claim 1, wherein the black photoconductor is located on the most downstream side with respect to the moving direction of the intermediate transfer member, and the color photoconductor is located on the upstream side. The image forming apparatus according to claim 2, wherein the black photoconductor is located on the most downstream side with respect to the moving direction of the recording material conveyance body, and the color photoconductor is located on the upstream side. The image forming apparatus according to claim 1, wherein distances between transfer positions at which toner images are transferred from the respective photosensitive members to the intermediate transfer member are all set equal. The image forming apparatus according to claim 2, wherein distances between transfer positions at which the toner images are transferred from the respective photosensitive members to the recording material carried on the recording material conveyance body are all set equal.

Images