JP3926806B2 - Color image forming apparatus - Google Patents

Description

  The present invention relates to a color image forming apparatus applied to a color copying machine, a color printer, a color facsimile, and the like, and in particular, an electrophotographic color image having a plurality of developing units and an intermediate transfer member carrying a color toner image. The present invention relates to a forming apparatus.

  As a conventional technique related to an electrophotographic color image forming apparatus having a plurality of developing devices and an intermediate transfer member that carries a color toner image, for example, Patent Document 1 (Japanese Patent Laid-Open No. 6 (1994)) previously filed by the present applicant. No. -289684)). The present invention relates to a color image forming apparatus comprising a plurality of color developing units that carry and convey a plurality of color developers and applied to a photoreceptor, and an intermediate transfer belt on which the developer on the photoreceptor is transferred to carry a color toner image. In the apparatus, position information detecting means for forming a plurality of position information portions for informing the intermediate transfer belt of position information, detecting the position information portions, and obtaining a position information detection signal for starting latent image formation on the photosensitive member The latent image formation is performed by counting the number of position information based on the position information detection signal used to start the formation of the latent image on the photoconductor, and performing the determination until the start of the latent image formation of the next plate. Start determination means is provided, and this makes it possible to start from the print enable state with the minimum wait time and to shorten the print time.

JP-A-6-289684 JP-A-2-18591

  2. Description of the Related Art Conventionally, in a color image forming apparatus that enables multicolor reproduction by applying electrophotography, a color separation light image is exposed to an electrostatic latent image carrier such as a photoconductor, and each formed latent image is respectively Developing with color separation light complementary color toner, transferring the resulting multiple toner images on the same intermediate transfer body to form a color image, and transferring the color image to transfer paper by electrostatic transfer There is known an image forming apparatus such as a full color copying machine. The transfer from the electrostatic latent image carrier to the intermediate transfer member is referred to as primary transfer, and the transfer from the intermediate transfer member to the transfer paper is referred to as secondary transfer.

  On the other hand, as a transfer member for electrostatically transferring a toner image from a photosensitive member to a transfer paper in a monochrome copying machine or a monochrome printer, a transfer roller system that is excellent in transferability of the transfer paper is known. Also in the above-described full-color copying machine, a transfer roller can be used as a secondary transfer member in order to electrostatically transfer the color toner image on the intermediate transfer member onto the transfer paper. In this case, since the toner images of a plurality of colors are sequentially transferred from the photosensitive member onto the intermediate transfer member, the transfer roller is separated from the intermediate transfer member in order to prevent contamination of the secondary transfer roller. When performing the secondary transfer while retracting to the position, it is necessary to move the transfer roller to a position where it abuts against the intermediate transfer member with the transfer paper interposed therebetween.

  By the way, when the secondary transfer member (transfer roller) is brought into contact with and separated from the intermediate transfer member in this way, the drive of the intermediate transfer member and the drive of the photosensitive member are also affected when the drive system and the drive system are connected to the photosensitive member. If the secondary transfer member (transfer roller) is brought into contact with or separated from the intermediate transfer member during primary transfer and / or optical writing, problems such as horizontal stripes may occur on the image. I found out.

Further, after the color image is transferred from the intermediate transfer member onto the transfer paper, 100% of the toner is not transferred and some toner remains attached to the surface of the intermediate transfer member. Therefore, a cleaning member installed in the vicinity of the intermediate transfer member cleans the toner adhering from the intermediate transfer member, and prevents the adhering toner from staining the next image.
In this case, since the toner images of a plurality of colors are sequentially transferred from the photosensitive member onto the intermediate transfer member, the toner image on the intermediate transfer member must be held during that time. When performing cleaning by retracting to a position separated from the transfer body, it is necessary to move the cleaning member to a position in contact with the intermediate transfer body. Such a color image forming apparatus is disclosed in Japanese Patent Laid-Open No. 2-18591. That is, in the technology described in the above publication, the cleaning blade is locked at a position away from the transfer medium by the positioning device, and the lock is controlled via the solenoid to release the lock, thereby preventing the transfer medium from being damaged by the cleaning blade. Yes.

  By the way, when the cleaning member is brought into contact with and separated from the intermediate transfer member in this way, if the drive of the intermediate transfer member and its drive system are connected to the photosensitive member, the driving of the photosensitive member is also affected. It has been discovered that if the cleaning member is brought into contact with or separated from the intermediate transfer member during writing and / or optical writing, problems such as horizontal stripes occur on the image.

The present invention has been made in view of the above problems, and the problems to be solved are as follows.
The present invention provides an intermediate transfer belt and a photoreceptor belt so that the secondary transfer member and the cleaning member do not contact and separate from the intermediate transfer member during optical writing and primary transfer during continuous printing. Color image formation that can increase the number of continuous prints (number of prints per unit time) most efficiently while preventing the occurrence of problems such as horizontal streaks on the image. It is an object (object) to provide a device.
In addition, the present invention prevents the secondary transfer member and the cleaning member from contacting and separating from the intermediate transfer body at least during optical writing during continuous printing so that the intermediate transfer belt and the photosensitive belt It prevents the drive from being affected, prevents the occurrence of defects such as horizontal stripes on the image, and also affects the drive of the intermediate transfer belt and the photosensitive belt to the maximum extent even during the primary transfer. It is an object of the present invention to provide a color image forming apparatus capable of preventing the occurrence of defects such as horizontal stripes on an image and increasing the number of continuous prints (number of prints per unit time) most efficiently. It is said.
Furthermore, the present invention provides an intermediate transfer belt and a photosensitive member so that the secondary transfer member and the cleaning member do not contact and separate from the intermediate transfer member during optical writing and primary transfer during continuous printing. A color image that can increase the number of continuous prints (number of prints per unit time) most efficiently while preventing the belt drive from being affected and causing problems such as horizontal streaks on the image. An object (object) is to provide a forming apparatus.

  In order to solve the above problems, the first means includes an electrostatic latent image carrier, and a plurality of developing units that develop the latent images formed on the electrostatic latent image carrier with toners of different colors. An intermediate transfer body on which toner images of respective colors formed on the electrostatic latent image carrier are sequentially transferred (primary transfer) and carry the toner images of the plurality of colors, and toner on the intermediate transfer body A transfer member capable of contacting / separating the intermediate transfer member for performing a secondary transfer process for transferring an image onto a transfer sheet, and an intermediate transfer member capable of contacting / separating the transfer residual toner on the intermediate transfer member In the color image forming apparatus having a cleaning member, the peripheral length of the intermediate transfer member is the maximum transfer paper length that can be output, and the distance from the writing position to the primary transfer position on the electrostatic latent image carrier. Longer than the sum of Based on the one of the positional information on Utsushitai it was configured to 1 printout for each intermediate transfer member 4 rotates.

The second means includes an electrostatic latent image carrier, a plurality of developing units for developing the latent images formed on the electrostatic latent image carrier with toners of different colors, and the electrostatic latent image carrier. The toner image of each color formed on the upper surface is sequentially transferred (primary transfer), and the toner image on the intermediate transfer member is transferred onto the transfer paper. Color image formation having a transfer member capable of contacting / separating to the intermediate transfer member for performing a secondary transfer process and a cleaning member capable of contacting / separating the intermediate transfer member for cleaning residual toner on the intermediate transfer member An image forming apparatus having a plurality of position information on the intermediate transfer member and carrying a plurality of color toner images on the intermediate transfer member with reference to one of the position information. Maximum transfer paper length possible and on electrostatic latent image carrier Continuous printing of color images by configuring the sum of the distance from the writing position to the primary transfer position to be longer than the intermediate transfer body circumference and shorter than the sum of the intermediate transfer body circumference and the distance between adjacent position information At this time, the position information serving as a reference on the intermediate transfer member is delayed by one for each print, and one print is output for every distance between the intermediate transfer member 4 rotations and the position information .

The third means is an electrostatic latent image bearing member, a means for performing optical writing on the electrostatic latent image bearing member to form a latent image, and developing the formed latent image with different color toners. A plurality of developing units, an intermediate transfer member that sequentially transfers a toner image of each color formed on the electrostatic latent image carrier, and carries the toner images of the plurality of colors, and the intermediate transfer member An intermediate transfer for cleaning the transfer residual toner on the intermediate transfer body, and a secondary transfer member that can contact and separate from the intermediate transfer body for performing a secondary transfer process for transferring the upper toner image onto the transfer paper In a color image forming apparatus having a cleaning member that can contact and separate from a body, the intermediate transfer member has a plurality of position information, and a toner image of a plurality of colors is displayed on the intermediate transfer member based on one of the position information. An image forming apparatus which is carried on top of each other, and is a color or monochromatic image During continuous printing, following the initiation of optical writing before the printing after the primary transfer completion Previous Symbol intermediate transfer member performs a contact operation to the intermediate transfer member of the secondary transfer member and the cleaning member, The positional information on the intermediate transfer member detected after the contact operation is selected as a reference for the image forming process of the next print .

According to a fourth means, in the color image forming apparatus of the third means, the position information to be selected is the first position information after completion of the primary transfer of the toner image having the size of the output transfer paper (claim). Item 1 ).
Of the first to fourth means described above, the third and fourth means are particularly adopted in the present application.

  In the color image forming apparatus of the first means, the peripheral length of the intermediate transfer member is the maximum transfer paper length that can be output and the distance from the writing position on the electrostatic latent image carrier to the primary transfer position. And when printing color images continuously, one print is output every four rotations of the intermediate transfer body with reference to one position information on the intermediate transfer body. During the optical writing, the secondary transfer member and the cleaning member do not contact / separate the intermediate transfer member, so that the driving of the intermediate transfer member and the electrostatic latent image carrier is prevented from being affected. There are no problems such as horizontal stripes on the top, and the number of continuous prints (number of prints per unit time) can be increased most efficiently.

  In the color image forming apparatus of the second means, the primary transfer is performed from the maximum transfer paper length having a plurality of position information on the intermediate transfer member and capable of being output, and the writing position on the electrostatic latent image carrier. The sum of the distance to the transfer position is longer than the peripheral length of the intermediate transfer body and shorter than the sum of the peripheral length of the intermediate transfer body and the adjacent position information distance. The reference position information on the intermediate transfer member is delayed by one, and one print is output for every distance between the intermediate transfer member 4 rotations and the position information, so that the secondary transfer member and the cleaning member are in the middle at least during optical writing. There is no contact / separation operation on the transfer body, and no secondary transfer member or cleaning member contacts the intermediate transfer body during the primary transfer, so that the intermediate transfer body and the electrostatic latent image carrier Such as horizontal stripes on the image due to the influence on driving Minimizing the degree occurs, it can be increased most efficiently print number during continuous (number of printed sheets per unit time).

The color image forming apparatus of the third means has a plurality of positional information on the intermediate transfer member, and when printing a color or single color image continuously , 1 is applied to the intermediate transfer member according to the size of the output transfer paper. After the completion of the next transfer and before the start of optical writing of the next print, the secondary transfer member and the cleaning member are brought into contact with the intermediate transfer member, and position information on the intermediate transfer member detected after the contact operation is obtained. Since it is configured to be selected as a reference for the image forming process of the next print, the secondary transfer member and the cleaning member are brought into contact with and separated from the intermediate transfer body during the primary transfer and during the optical writing of the next print. Therefore, it is possible to prevent the drive of the intermediate transfer member and the electrostatic latent image carrier from being affected, and there is no occurrence of problems such as horizontal stripes on the image. (Per unit time Rino number of prints) can be a lot of.

In the color image forming apparatus of the fourth means, in the color image forming apparatus of the third means, the position information to be selected, and the first positional information after the primary transfer completion of the toner image size in the transfer sheet to be output Therefore, since the secondary transfer member and the cleaning member do not contact / separate the intermediate transfer member during the primary transfer and the optical writing of the next print, the intermediate transfer member and the electrostatic latent image carrier Is not affected, and there is no occurrence of defects such as horizontal stripes on the image, and the number of continuous prints (number of prints per unit time) can be increased most efficiently.

  Hereinafter, embodiments of the present invention will be described in detail based on the illustrated examples.

FIG. 1 is a schematic configuration diagram of a full-color printer showing a configuration example of an image forming apparatus according to the present invention.
In the printer shown in FIG. 1, a belt-like photosensitive member (photosensitive belt) 1 serving as an electrostatic latent image carrier is uniformly charged by a charging charger 4, and then a laser light source, an optical deflector such as a rotary polygon mirror, A laser optical device 5 comprising various lenses, mirrors, etc. is scanned and exposed based on image information to form an electrostatic latent image on the surface. Here, the image information to be exposed is single-color image information obtained by separating a desired full-color image into yellow, magenta, cyan, and black color information. The electrostatic latent image formed on the photoreceptor belt 1 includes a rotary color developing device 6 having three developing means (each color developing device) containing yellow, magenta, and cyan color toners, and the color developing device. 6 is developed with predetermined yellow, magenta, cyan, and black toners by a black developing device 7 which is a developing means containing black toner provided separately from the toner 6, and an image for each color is formed on the photosensitive belt 1. It is formed.

  Each of the color developing device 6 and the black developing device 7 is provided with developing rollers that are close to or in contact with the photosensitive belt 1 at predetermined positions, and the latent image on the photosensitive belt 1 is visualized by non-contact development or contact development. It has a function to convert.

In FIG. 1, reference numeral 10 denotes an intermediate transfer belt as an intermediate transfer member. The intermediate transfer belt 10 is installed between rotating rollers 11 and 12, and is rotated in the direction of arrow B in the figure by driving of the rotating rollers. .
The photosensitive belt 1 is installed between the rotating rollers 2 and 3 and is rotated in the direction of the arrow A in the figure by driving the rotating rollers, and each color image formed on the photosensitive belt 1 is a photosensitive belt. A primary transfer bias brush 13 provided in the intermediate transfer belt 10 is provided on the intermediate transfer belt 10 that rotates in the direction of arrow B in the drawing in synchronization with 1 for each of yellow, magenta, cyan, and black. By applying an appropriate voltage, sequential transfer (primary transfer) is performed sequentially. The yellow, magenta, cyan, and black images superimposed on the intermediate transfer belt 10 are collectively transferred by the transfer roller 14 onto the transfer paper conveyed from the paper feed cassette 8 to the transfer unit via the paper feed roller 9a and the registration roller 9b. Transfer (secondary transfer) is performed. After the transfer is completed, the transfer paper is fixed by the fixing device 18 to complete a full color image.

  In the figure, reference numeral 15 denotes a waste toner collecting container including a cleaning blade 15A for cleaning the surface of the photosensitive belt 1, 16 denotes a cleaning device for the intermediate transfer belt 10, and a cleaning member (cleaning blade or the like) 16A of the cleaning device 16 is During image formation, it is kept at a position separated from the surface of the intermediate transfer belt 10 and is contacted / separated (not shown) so as to be in pressure contact with the surface of the intermediate transfer belt 10 as shown in the drawing only when cleaning the toner image after paper transfer. A mechanism is provided.

FIG. 2 shows an embodiment of a developing device related to the color image forming apparatus of the present invention.
In the vicinity of the photosensitive belt 1 described above, a rotating type (also referred to as revolver type or rotary type) developing device 6 as a color developing device according to the present invention, and a black developing device provided separately from the color developing device 6. 7 is arranged. In the rotary developing device 6, a casing 20 forming a rotating body is provided to be rotatable about a rotation center O, and the casing 20 is rotated in the direction of arrow C by a drive mechanism (not shown). Further, the casing 20 has a shape that divides the developing device into three parts, whereby yellow, magenta, and cyan color developing units 22-Y, M, and C are formed.

  FIG. 3 shows a state in which one developing unit 22Y in the color developing device 6 is in the developing position, and FIG. 4 is an enlarged view showing only one developing unit 22Y. Each developing device 22-Y, M, C is provided with a cylindrical developing roller 23-Y, M, C as a developer conveying member. Each of the developing rollers 23-Y, M, and C is disposed so that a part of the developing roller 23-Y, M, and C is exposed to the outside from the opening provided in the casing 20, and the casing 20 is in the direction of arrow C in the figure in synchronization with the color information. The electrostatic latent image is developed with a developing roller of a color corresponding to the color information.

  The color developing device 6 of this configuration example is a developing device using a non-magnetic one-component developer, and each of the developing devices 22-Y, M, and C stores toners of yellow, magenta, and cyan colors. The electrostatic latent image formed on the photosensitive belt 1 is sequentially developed by selectively rotating around the rotation center O to the developing position. Each developed image (each color toner image) formed on the photosensitive belt 1 is sequentially superimposed and transferred onto the intermediate transfer belt 10 as described above, and thereafter, a plurality of color toners on the intermediate transfer belt 10 are transferred. A full color image is formed by collectively transferring the image onto the transfer paper.

  4 shows only the configuration of the yellow developing unit 22Y, the configurations of the magenta and cyan color developing units 22-M and C are the same. The developing roller 23Y (M, C) rotates in the same direction as the movement direction of the photosensitive belt 1 (in the direction of arrow A in the figure) at a position facing the photosensitive belt 1 with a predetermined linear velocity ratio. It is rotated in the direction of arrow D in the figure. In the vicinity of the developing roller 23Y (M, C), a supply roller 31Y (M, C) made of an elastic material such as foamed polyurethane is provided, and rubs against the developing roller 23Y (M, C) at the rubbing portion. In addition, the developing roller 23Y (M, C) rotates in the D direction so that the moving direction of both rollers is the same in the rubbing portion, and the supply roller 31Y (M, C) has a predetermined linear velocity with the developing roller. It is provided to rotate in the E direction with a ratio. In the unit, a thin blade 32Y (M, C) made of an elastic body such as a stainless steel plate having a thickness of about 0.1 mm or urethane rubber is in contact with the developing roller 23Y (M, C) at one end. It is provided as follows. Further, in the toner transport space 34Y (M, C) in the unit of the developing unit, a first toner transport member (coil screw or the like) 33Y (M, C) for supplying toner into the unit from a toner container (not shown). ) And a second toner conveying member (coil screw or the like) 35Y (M, C) for collecting excess toner in the unit into the toner storage unit is provided. The toner is circulated by the toner conveying member.

Next, as shown in FIGS. 2 and 3, the black developing device 7 is a type of developing device in which black toner is contained in the developing container 41, and is integrated as a so-called developing cartridge in which the life of the developing device is replaced when the toner ends. The developing device formed in the above. In the black developing device 7 as well, as with the developing devices 22-Y, M, and C of the color developing device 6, the developing roller 23 has a predetermined linear velocity ratio with the photosensitive belt 1 in the moving direction of the photosensitive belt 1 (in the drawing). Arranged opposite to the photoreceptor belt 1 so as to rotate in the same direction as the arrow A direction). Further, a supply roller 31 made of an elastic material such as foamed polyurethane is disposed above the developing roller 23 and rubs against the developing roller 23 at the rubbing portion and moves in the same direction as the developing roller 23 at the rubbing portion. Thus, it is provided to rotate with a predetermined linear velocity ratio. Further, a thin layer blade 32 made of an elastic material such as a stainless steel plate having a thickness of about 0.1 mm or urethane rubber is provided in the developing container 41 so that one end thereof is in contact with the developing roller 23. In the developing container 41, a paddle 42 having a plurality of blade-like portions for agitating the toner in the vicinity of the thin blade 32 is provided, and a first toner for conveying and agitating the toner to the supply roller 31 and the developing roller 23 side. An agitator 43 and a second agitator 44 are provided.
The black developing device 7 is pressurized in a direction away from the photosensitive belt 1 by a pressing means (not shown) so that the developing roller 23 is brought into contact with and separated from the photosensitive belt 1 by the rotation of the cam 45. It has become.

  The configuration example of the color image forming apparatus according to the present invention has been described by taking the full color printer as an example. Hereinafter, an embodiment of the color image forming apparatus according to the present invention will be described.

First, a color image forming apparatus in which the first means is implemented will be described with reference to FIG.
The configuration of the full-color printer shown in FIG. 5 is basically the same as that shown in FIG. 1, and the components denoted by the same reference numerals are the same constituent members. In this embodiment, as shown in FIG. The length of the belt 10 is longer than that of the configuration shown in FIG. 1, and the peripheral length of the intermediate transfer belt 10 is the maximum transfer paper length that can be output, and a photosensitive member that is an electrostatic latent image carrier. The optical writing position 5A and the primary transfer bias brush 13 are arranged around the photosensitive belt so as to be longer than the sum of the distance from the writing position on the belt 1 to the primary transfer position.

  As a specific example, the peripheral length of the intermediate transfer belt 10 is 442.1 mm, the maximum transferable paper length that can be output is 297 mm in length of A4, and from the optical writing position 5A on the photosensitive belt 1 to the primary transfer position. The distance was 128.1 mm and the sum was 425.1 mm. With this configuration, from the start of optical writing to the primary transfer can be completely completed before the intermediate transfer belt 10 makes one round. Accordingly, there is no time overlap between the primary transfer process and the optical writing process of the next plate, and there is a time gap between the completion of the primary transfer and the optical writing of the next plate. The contact and separation of the secondary transfer roller 14 with respect to the intermediate transfer belt 10 and the contact and separation of the intermediate transfer belt cleaning member 16A with respect to the intermediate transfer belt 10 can be performed in this time gap. Then, with one position information 46 on the intermediate transfer belt 10 as a reference, one print output is made every four rotations of the intermediate transfer belt, so that the number of continuous prints (number of prints per unit time) can be increased most efficiently. .

Here, FIG. 6 shows a schematic timing chart of the color image forming apparatus of the first means, and its operation will be described.
5 and 6, the photosensitive belt 1 is first driven, and at the same time, charging is performed by the charging charger 4. Next, an exposure process (optical writing) is performed by the laser optical device 5, and a yellow electrostatic latent image is formed on the photosensitive belt 1. When the electrostatic latent image moves to the development position, development is performed by the yellow developer 22Y. The toner image is transferred to the intermediate transfer belt 10 by applying a bias by the primary transfer bias brush 13. Next, the color developing device 6 is rotated by the rotation driving mechanism, and the magenta developing device 22M is opposed to the developing position on the photosensitive belt 1. Further, an exposure process (optical writing) is performed by the laser optical device 5 so as to be synchronized with the toner image on the intermediate transfer belt 10, and a magenta electrostatic latent image is formed on the photosensitive belt 1. Development is performed in synchronization with the movement of the image to the development position. The magenta toner image is similarly transferred and superimposed on the intermediate transfer belt 10 by bias application by the primary transfer bias brush 13. The steps up to here are the same as those of the third plate cyan in FIG. 6, and the image forming steps of the first and second plates are omitted in FIG.

Next, as shown in FIG. 6, cyan latent image formation, development, and primary transfer of a cyan toner image are performed. After the cyan development, the color developing device 6 is rotated by a rotation driving mechanism, and any developing unit is stopped at a reference position that does not face the photosensitive belt 1. Finally, a black electrostatic latent image is formed so as to be synchronized with the toner image on the intermediate transfer belt 10, and the black developing unit 7 is synchronized with the movement of the electrostatic latent image to the developing position. The cam 45 rotates to move to the developing position on the photosensitive belt 1 and black development is performed. The black toner image is similarly transferred and transferred onto the intermediate transfer belt 10.
After all the primary transfer of the black toner image is completed, the secondary transfer roller 14 moves from the position retracted from the intermediate transfer belt 10 to the contact position with the intermediate transfer belt 10 to perform the secondary transfer. . At the same time, a cleaning member (cleaning blade or the like) 16A of the intermediate transfer belt cleaning device 16 comes into contact with the intermediate transfer belt 10 to perform cleaning.

  This timing chart is for continuous printing. After all primary transfer of the fourth printing (black) toner image of the previous printing is completed, optical writing of the first printing (yellow) of the next printing is performed. As shown in FIG. 6, in the color image forming apparatus of this embodiment, the contact operation of the secondary transfer roller 14 and the contact operation of the cleaning member 16A of the intermediate transfer belt 10 to the intermediate transfer belt 10 are the first print of the next print. This is performed before the start of (yellow) optical writing.

In this way, the contact operation of the secondary transfer roller 14 and the contact operation of the cleaning member 16A of the intermediate transfer belt 10 to the intermediate transfer belt 10 are performed after the primary transfer is completed and the light of the first print (yellow) of the next print. By carrying out before the start of writing, during the primary transfer and during optical writing of the next print, the drive of the intermediate transfer belt 10 and the photosensitive belt 1 is not affected, and a horizontal stripe or the like is formed on the image. There are no problems.
Further, after all the primary transfer of the first printing (yellow) toner image of the next print is completed, the second printing (magenta) of the next printing is optically written. As shown in FIG. 6, in the color image forming apparatus of this embodiment, the separation operation of the secondary transfer roller 14 and the separation operation of the cleaning member 16A of the intermediate transfer belt 10 from the intermediate transfer belt 10 Performed before the start of optical writing of (magenta).

In this way, the separation operation of the secondary transfer roller 14 and the separation operation of the cleaning member 16A of the intermediate transfer belt 10 from the intermediate transfer belt 10 are performed after the completion of the primary transfer of the first plate (yellow) of the next print and Performing before the second writing (magenta) of the next print starts optical writing affects the driving of the intermediate transfer belt 10 and the photosensitive belt 1 during the primary transfer and the optical writing of the next print. The image is not given, and a defect such as a horizontal stripe does not occur on the image.
Then, with one position information 46 on the intermediate transfer belt 10 as a reference, one print is output every four rotations of the intermediate transfer belt 10, so that the number of continuous prints (the number of prints per unit time) can be obtained most efficiently. You can do more.

Next, a color image forming apparatus in which the second means is implemented will be described with reference to FIG.
The configuration of the full-color printer shown in FIG. 7 is basically the same as that shown in FIG. 1, and those given the same reference numerals are the same constituent members. In this embodiment, as shown in FIG. A plurality of pieces of position information (for example, marks arranged at equal intervals in the circumferential direction of the intermediate transfer belt) 46 are provided on the belt 10, and one of the pieces of position information is used as a reference (for example, a position serving as the reference). The maximum transfer paper length that can be output, and is an image forming apparatus that carries a plurality of color toner images superimposed on the intermediate transfer belt 10 by detecting position information by means of position information detection means such as a reflective photosensor. And the distance from the optical writing position 5A on the photosensitive belt 1 serving as the electrostatic latent image carrier to the primary transfer position is longer than the circumference of the intermediate transfer belt 10 and the circumference of the intermediate transfer belt Shorter than the sum of the distance between adjacent positions Forms.

  Specifically, the maximum transfer paper length that can be output is 297 mm in length A4, and the distance from the optical writing position 5A on the photosensitive belt 1 to the primary transfer position (primary transfer bias brush 13 position) is 128.mm. 1 mm, the sum is 425.1 mm, the peripheral length of the intermediate transfer belt 10 is 393 mm, and eight position information 46 is provided on the intermediate transfer belt 10 at equal intervals. The sum of the distance between adjacent position information 49.1 mm was 442.1 mm. Then, during continuous printing of color images, the reference position information on the intermediate transfer belt is delayed by one for each print, and one print is output for every rotation of the intermediate transfer belt + the distance between the position information.

  Here, FIG. 8 shows an outline of a timing chart of the color image forming apparatus of the second means. In the timing chart of FIG. 8, the image forming operation portion of the first and second plates (yellow, magenta) is omitted, and the operation from the third plate (cyan) optical writing is shown. In addition, the inverted triangle mark at the top of the drawing indicates the position information on the intermediate transfer belt as a reference for the image forming process.

As shown in FIG. 8, in this embodiment, during continuous printing of color images, the position information 46 serving as a reference on the intermediate transfer belt 10 is delayed by one for each print, and the intermediate transfer belt 4 rotations + the distance between the position information. Since one print is output every time, the primary transfer process of the fourth printing (black) toner image of the previous print and the optical writing process of the first printing (yellow) of the next printing may overlap in time. Absent.
Further, as shown in FIG. 8, in the color image forming apparatus according to the present embodiment, the contact operation of the secondary transfer roller 14 and the contact operation of the cleaning member 16A of the intermediate transfer belt 10 to the intermediate transfer belt 10 are the fourth of the previous print. This is performed after all the primary transfer of the plate (black) toner image is completed and before the optical writing of the first plate (yellow) of the next print is completed.

  In this way, the contact operation of the secondary transfer roller 14 and the contact operation of the cleaning member 16A of the intermediate transfer belt 10 to the intermediate transfer belt 10 are performed after the completion of the primary transfer and the first printing (yellow) of the next print. By carrying out before the start of optical writing, during the primary transfer and during the optical writing of the next print, the drive of the intermediate transfer belt 10 and the photosensitive belt 1 is not affected, and horizontal stripes are formed on the image. The problem does not occur.

The separation operation of the secondary transfer roller 14 and the separation operation of the cleaning member 16A of the intermediate transfer belt 10 from the intermediate transfer belt 10 are performed at least after the optical writing process of the first printing (yellow) of the next print. This is performed before the second printing (magenta) of the next print is started.
That is, the influence on the drive of the intermediate transfer belt 10 and the photosensitive belt 1 by the separation operation of the secondary transfer roller 14 and the separation operation of the cleaning member 16A of the intermediate transfer belt 10 from the intermediate transfer belt 10 is the optical writing process. Since the influence on the primary transfer process is small, the overlap with at least the optical writing process is avoided.

  With this configuration, the intermediate transfer during the optical writing process and the primary transfer process by the contact operation of the secondary transfer roller 14 and the contact operation of the cleaning member 16A of the intermediate transfer belt 10 to the intermediate transfer belt 10 is achieved. The optical writing can be performed by eliminating the influence on the driving of the belt 10 and the photosensitive belt 1 and by the separating operation of the secondary transfer roller 14 and the separating operation of the cleaning member 16A of the intermediate transfer belt 10 from the intermediate transfer belt 10. The influence on the driving of the intermediate transfer belt 10 and the photosensitive belt 1 can be eliminated, and the circumference of the intermediate transfer belt can be shortened under the conditions. As a result, the number of printed sheets at the most efficient time can be obtained. (Number of prints per unit time) can be increased.

Next, a color image forming apparatus in which the third means is implemented will be described with reference to FIG.
In this embodiment, as shown in FIG. 7, the intermediate transfer belt 10 has a plurality of position information (for example, marks set at equal intervals in the circumferential direction of the intermediate transfer belt) 46, and one of them is included. An image forming apparatus that holds toner images of a plurality of colors on the intermediate transfer belt 10 with the position information as a reference (for example, the position information serving as the reference is detected by position information detection means such as a reflective photosensor). In the continuous printing of color images, position information on the intermediate transfer belt as a reference for the image forming process for the next print is selected according to the size of the transfer paper to be output.

  Specifically, when eight pieces of positional information 46 are provided at equal intervals on the intermediate transfer belt 10 and a postcard size (length 148 mm) is output, the reference (optical writing) of the next print image forming process is performed. As the position information on the intermediate transfer belt 10 to be started), the position information two before is selected from the position information on the intermediate transfer belt 10 which has been used as the reference (starting optical writing) of the image formation process of the previous print.

  Here, FIG. 9 shows an outline of a timing chart of the color image forming apparatus of the third means. In the timing chart of FIG. 9, the image forming operation portion of the first and second plates (yellow, magenta) is omitted and the operation from the third plate (cyan) optical writing is shown. In addition, the inverted triangle mark at the top of the drawing indicates the position information on the intermediate transfer belt as a reference for the image forming process.

As shown in FIG. 9, during continuous printing of a postcard size color image, the positional information on the intermediate transfer belt as the reference (image writing start) of the next print image formation process is used as the position information on the previous print. The position information two before is selected from the position information on the intermediate transfer belt 10 used as the reference (start of optical writing).
As a result, the primary transfer process of the fourth printing (black) toner image of the previous print and the optical writing process of the first printing (yellow) of the next printing do not overlap in time and are minimized. Become. Therefore, the contact operation of the secondary transfer roller 14 and the contact operation of the cleaning member 16A of the intermediate transfer belt 10 to the intermediate transfer belt 10 are performed after the completion of the primary transfer and for the first printing (yellow) of the next print. By performing the process before the start of the copying, the horizontal streak on the image is not affected during the primary transfer of the previous print and the optical writing of the next print without affecting the driving of the intermediate transfer belt 10 and the photosensitive belt 1. There will be no problems such as. Since the start of the next print image forming process can be advanced by twice the distance between the position information, the number of continuous prints (the number of prints per unit time) can be increased most efficiently.

Next, an outline of a timing chart of the color image forming apparatus of the fourth means will be described with reference to FIG.
As shown in FIG. 9, during the continuous printing of postcard size color images, the contact operation of the secondary transfer roller 14 and the cleaning member for the intermediate transfer belt 10 immediately after the completion of the optical writing process of the fourth print (black) of the previous print The contact operation of 16A to the intermediate transfer belt 10 is performed, and the subsequent positional information on the intermediate transfer belt 10 is used as a reference (starting of optical writing) of the image formation process of the next print. As a result, the primary transfer process of the fourth printing (black) toner image of the previous print and the optical writing process of the first printing (yellow) of the next printing do not overlap in time and are minimized. Become. Therefore, the contact operation of the secondary transfer roller 14 and the contact operation of the cleaning member 16A of the intermediate transfer belt 10 to the intermediate transfer belt 10 are performed after the completion of the primary transfer and for the first printing (yellow) of the next print. By performing the process before the start of the copying, the horizontal streak on the image is not affected during the primary transfer of the previous print and the optical writing of the next print without affecting the driving of the intermediate transfer belt 10 and the photosensitive belt 1. There will be no problems such as. Then, the start of the next print image forming process can be advanced twice as much as the distance between the position information. As a result, the number of continuous prints (the number of prints per unit time) can be increased most efficiently.

In the above description of the embodiment, the maximum transferable paper length that can be output is 297 mm in A4 length, but in a color image forming apparatus in which the maximum transferable paper length that can be output is A3 length, the A4 length is 297 mm. If A3 length 420 mm is applied, the same apparatus configuration and timing control can be applied, and the same effect can be achieved.
It is also possible to carry two A4 horizontal toner images on the intermediate transfer belt. In this case, A4 horizontal 210 mm × 2 + paper interval (for example, 40 mm) = 460 mm instead of A4 vertical 297 mm. By applying the above, the same device configuration and timing control can be applied, and the same operational effects can be achieved.

In the third and fourth means, not only when forming a color image but also during continuous printing of a single color image, the positional information on the intermediate transfer belt as the reference for the image forming process of the next print is the same. Can be selected.
Further, in the embodiment, the length of the maximum transfer paper that can be output is A4 length and the size of the output transfer paper is postcard size (148 mm). However, the maximum transfer paper size is A3 length or A4 width 210 mm × 2 + paper gap (for example, 40 mm) = 460 mm, and the size of the output transfer paper can be appropriately applied as small as A4 horizontal or B5 vertical.

  The color image forming apparatus of the present invention described above can be suitably applied to a color copying machine, a color printer, a color facsimile, and the like.

1 is a schematic configuration diagram illustrating a configuration example of a color image forming apparatus according to the present invention. FIG. 2 is a schematic configuration diagram illustrating an example of a color developing device (rotary developing device) and a black developing device of the color image forming apparatus illustrated in FIG. 1, illustrating a state where each developing device is in a standby position. FIG. 2 is a schematic configuration diagram illustrating an example of a color developing device (rotary developing device) and a black developing device of the color image forming apparatus shown in FIG. 1, and a state when one developing device in the color developing device reaches a developing position. FIG. FIG. 4 is a diagram illustrating a configuration example of one developing device in the rotary developing device illustrated in FIGS. 1 to 3. 1 is a schematic configuration diagram of a color image forming apparatus showing an embodiment of the present invention. 6 is a timing chart illustrating an example of an image forming operation of the color image forming apparatus having the configuration illustrated in FIG. 5. It is a schematic block diagram of the color image forming apparatus which shows another Example of this invention. 8 is a timing chart illustrating an example of an image forming operation of the color image forming apparatus having the configuration illustrated in FIG. 7. 8 is a timing chart showing another example of the image forming operation of the color image forming apparatus having the configuration shown in FIG. 7.

Explanation of symbols

1: Photosensitive belt (electrostatic latent image carrier)
2, 3: Photoconductor belt rotating roller 4: Charger charger 5: Laser optical device 5A: Optical writing position 6: Color developing device (rotary developing device)
7: Black developing device 8: Paper feed cassette 9a: Paper feed roller 9b: Registration roller 10: Intermediate transfer belt (intermediate transfer member)
11, 12: Intermediate transfer belt rotating roller 13: Primary transfer bias brush 14: Transfer roller 15: Waste toner collection container 15A: Cleaning blade 16: Cleaning device for intermediate transfer belt 16A: Cleaning member (cleaning blade, etc.)
18: Fixing device 20: Casing 22-Y, M, C: Developing devices 23, 23-Y, M, C of each color: Developing rollers 31, 31Y (M, C): Supply rollers 32, 32Y (M, C) : Thin layer blade 33Y (M, C): First toner conveying member 34Y (M, C): Toner conveying space 35Y (M, C): Second toner conveying member 41: Developing container 42: Paddle 43: First 1 agitator 44: second agitator 45: cam 46: position information

Claims (1)

An electrostatic latent image carrier, means for optically writing on the electrostatic latent image carrier to form a latent image, and a plurality of developing units for developing the formed latent images with toners of different colors, respectively. A toner image for each color formed on the electrostatic latent image carrier is sequentially primary-transferred, and the toner images on the intermediate transfer member are transferred by superimposing the toner images of the plurality of colors. A secondary transfer member that can be brought into contact with and separated from the intermediate transfer member for performing a secondary transfer step for transferring onto the paper, and an intermediate transfer member for cleaning the transfer residual toner on the intermediate transfer member. In a color image forming apparatus having a cleaning member,
An image forming apparatus having a plurality of position information on the intermediate transfer body, and carrying a plurality of color toner images on the intermediate transfer body with reference to one of the position information. during continuous printing, following the initiation of optical writing before the printing after the primary transfer completion Previous Symbol intermediate transfer member performs a contact operation to the intermediate transfer member of the secondary transfer member and the cleaning member, The position information on the intermediate transfer member detected after the contact operation is selected as a reference for the image forming process of the next print , and the selected position information is a toner image of the size of the output transfer paper. A color image forming apparatus characterized in that the first position information after the primary transfer is completed .

Images