JP2004206154A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus which increases the number of prints per unit time in the most efficient continuous photography while preventing trouble such as a lateral stripe from being formed on an image. <P>SOLUTION: The color image forming apparatus has a photoreceptor 1, a plurality of developing units 7, 22-Y, M, and C which develop latent images formed on the photoreceptor, an intermediate transfer body 10 to which toner images of respective colors formed on the photoreceptor are primarily transferred, one over another, in order, a transfer member 14 for secondarily transferring the toner image on the intermediate transfer body onto transfer paper, and a cleaning member 16A for cleaning transfer-left toner on the intermediate transfer body. A plurality of pieces of position information 46 are provided on the intermediate transfer body and on the basis of one of the pieces of position information, toner images of a plurality of colors are carried on the intermediate transfer body, one over another. <P>COPYRIGHT: (C)2004,JPO&NCIPI

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 more particularly, to an electrophotographic color image having a plurality of developing units and an intermediate transfer member carrying a color toner image. It relates to a forming apparatus.

  As a prior art relating to an electrophotographic color image forming apparatus having a plurality of developing devices and an intermediate transfer member carrying a color toner image, for example, Japanese Patent Application Laid-Open No. -289684). The present invention relates to a color image forming apparatus including a plurality of color developing units that carry and convey a plurality of color developers and apply them to a photoreceptor, and an intermediate transfer belt that carries a color toner image on which the developer on the photoreceptor is transferred. In the apparatus, a plurality of position information sections for notifying position information to the intermediate transfer belt are formed, and position information detection means for detecting the position information sections and obtaining a position information detection signal for starting formation of a latent image on the photoreceptor is provided. A latent image forming device that counts the number of position information based on the position information detection signal used to start the latent image formation on the photoreceptor, and determines until the start of the next plate latent image formation. The apparatus is provided with a start determination means, whereby it is 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 an electrophotographic method, a color separation light image is exposed to an electrostatic latent image carrier such as a photosensitive member, and each formed latent image is individually exposed. Developed with complementary color toner of color separation light, superimposed and transferred multiple obtained toner images on the same intermediate transfer body to form a color image, and transferred the color image to transfer paper by electrostatic transfer An image forming apparatus such as a full-color copying machine of the type described above is known. The transfer from the electrostatic latent image carrier to the intermediate transfer member is called primary transfer, and the transfer from the intermediate transfer member to transfer paper is called secondary transfer.

  On the other hand, in a monochrome copying machine or a monochrome printer, as a transfer member for electrostatically transferring a toner image from a photoconductor to a transfer sheet, a transfer roller system excellent in transferability of the transfer sheet 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 to transfer paper. In this case, since a plurality of color toner images are sequentially transferred from the photoreceptor onto the intermediate transfer member, the transfer roller is separated from the intermediate transfer member during that time to prevent the secondary transfer roller from being stained. When the secondary transfer is performed after being retracted to the position, it is necessary to move the transfer roller to a position where the transfer roller is in contact with 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 or separated from the intermediate transfer member in this way, the drive of the intermediate transfer member and the drive system of the intermediate transfer member are also affected when the drive system is connected to the photosensitive member. If the secondary transfer member (transfer roller) is moved toward and away from the intermediate transfer member during the primary transfer and / or the optical writing, a problem such as a horizontal stripe may occur on the image. I was discovered.

Also, 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 on the surface of the intermediate transfer member. Therefore, a cleaning member provided in close proximity to the intermediate transfer member cleans toner adhering from the intermediate transfer member, and prevents the adhered toner from staining the next image.
In this case, since the toner images of a plurality of colors are sequentially transferred from the photoreceptor onto the intermediate transfer member, the toner image on the intermediate transfer member must be held during that time. When the cleaning member is evacuated to a position separated from the transfer member and performs cleaning, it is necessary to move the cleaning member to a position where it contacts the intermediate transfer member. Such a color image forming apparatus is disclosed in Patent Document 2 (JP-A-2-18591). That is, in the technique described in the above publication, the cleaning blade is locked at a position away from the transfer medium by the positioning device, and the unlocking and locking are controlled via the solenoid, thereby preventing the transfer blade from being damaged by the cleaning blade. I have.

  By the way, when the cleaning member is brought into contact with or separated from the intermediate transfer body in this way, the drive of the intermediate transfer body and, if the drive system thereof is connected to the photosensitive body, also affects the drive of the photosensitive body. When the cleaning member is moved toward and away from the intermediate transfer member during and / or during optical writing, it has been found that defects 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.
SUMMARY OF THE INVENTION The present invention provides an intermediate transfer belt and a photoreceptor belt that prevent a secondary transfer member and a cleaning member from contacting and separating from an intermediate transfer member during optical writing and primary transfer during continuous printing. Image formation that can increase the number of continuous prints (the number of prints per unit time) most efficiently while preventing the influence on the drive of the printer and preventing the occurrence of defects such as horizontal stripes 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 member at least during optical writing at the time of continuous printing, so that the intermediate transfer belt and the photosensitive belt can be moved. Prevents the drive from being affected, prevents horizontal streaks from occurring on the image, and affects the drive of the intermediate transfer belt and photoreceptor belt to the maximum 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 troubles such as horizontal stripes on an image, and increasing the number of continuous prints (the number of prints per unit time) most efficiently. And
Further, the present invention provides an intermediate transfer belt and a photosensitive member that prevent a secondary transfer member and a cleaning member from operating and separating from an intermediate transfer member during optical writing and primary transfer during continuous printing. A color image that can increase the number of continuous prints (the number of prints per unit time) most efficiently while preventing the belt driving from being affected and preventing the occurrence of defects such as horizontal stripes on the image. It is an object (object) to provide a forming apparatus.

  In order to solve the above problems, a first means includes an electrostatic latent image carrier, and a plurality of developing devices for developing latent images formed on the electrostatic latent image carrier with toners of different colors. An intermediate transfer member for sequentially transferring (primary transfer) toner images of respective colors formed on the electrostatic latent image carrier and carrying the toner images of the plurality of colors in an overlapping manner; and a toner on the intermediate transfer member. A transfer member capable of contacting and separating from the intermediate transfer member for performing a secondary transfer step of transferring an image onto transfer paper; and a transfer member capable of contacting and separating from the intermediate transfer member for cleaning residual transfer toner on the intermediate transfer member. In a color image forming apparatus having a cleaning member, a peripheral length of the intermediate transfer body is set to a maximum length of transfer paper that can be output, a distance from a writing position on the electrostatic latent image carrier to a primary transfer position, and The length of the image is 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 devices for developing latent images formed on the electrostatic latent image carrier with toners of different colors, and an electrostatic latent image carrier. The toner images of the respective colors formed thereon are sequentially transferred (primary transfer), and an intermediate transfer body carrying the toner images of the plurality of colors in an overlapping manner, and the toner image on the intermediate transfer body is transferred onto transfer paper. A color image forming apparatus including a transfer member that can be brought into and away from the intermediate transfer member for performing a secondary transfer process, and a cleaning member that can be brought into and away from the intermediate transfer member to clean residual toner on the intermediate transfer member In the apparatus, a plurality of position information is provided on the intermediate transfer body, and a plurality of color toner images are carried on the intermediate transfer body in a superimposed manner based on one of the position information. 1). The sum of the maximum length of transfer paper that can be output and the distance from the writing position on the electrostatic latent image carrier to the primary transfer position is set to be longer than the intermediate transfer member circumferential length, and It is configured to be shorter than the sum of the length and the distance between adjacent position information. During continuous printing of a color image, the reference position information on the intermediate transfer body is delayed by one for each print, and the intermediate transfer body is rotated 4 times + position. One print is output for each information distance (claim 2).

  The third means includes an electrostatic latent image carrier, a plurality of developing devices for developing latent images formed on the electrostatic latent image carrier with toners of different colors, and an electrostatic latent image carrier. The toner images of the respective colors formed thereon are sequentially transferred (primary transfer), and an intermediate transfer body carrying the toner images of the plurality of colors in an overlapping manner, and the toner image on the intermediate transfer body is transferred onto transfer paper. A color image forming apparatus including a transfer member that can be brought into and away from the intermediate transfer member for performing a secondary transfer process, and a cleaning member that can be brought into and away from the intermediate transfer member to clean residual toner on the intermediate transfer member In the apparatus, a plurality of position information is provided on the intermediate transfer body, and a plurality of color toner images are carried on the intermediate transfer body in a superimposed manner based on one of the position information. 1). Then, during continuous printing of a color or monochrome image, position information on the intermediate transfer body to be used as a reference for an image forming process of the next print is selected according to the size of the transfer paper to be output. 3).

  The fourth means is configured such that in the color image forming apparatus of the third means, the selected position information is the first position information after the primary transfer of the size of the output transfer paper is completed. .

  In the color image forming apparatus of the first means, the peripheral length of the intermediate transfer body is determined by the maximum length of the transfer paper that can be output, and the distance from the writing position on the electrostatic latent image carrier to the primary transfer position. During continuous printing of a color image, one print is output every four rotations of the intermediate transfer body based on one piece of position information on the intermediate transfer body. Since the secondary transfer member and the cleaning member do not contact / separate from the intermediate transfer member during optical writing, it does not affect the driving of the intermediate transfer member and the electrostatic latent image carrier, thereby preventing image Abnormalities such as horizontal stripes do not occur on the top, and the number of continuous prints (the number of prints per unit time) can be increased most efficiently.

  The color image forming apparatus of the second means has a plurality of pieces of position information on the intermediate transfer body, and the primary transfer paper length is determined based on the maximum length of transfer paper that can be output and the writing position on the electrostatic latent image carrier. The sum of the distance to the transfer position is 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. One print is output every four rotations of the intermediate transfer member + distance between the position information by delaying the reference position information on the intermediate transfer member by one, so that at least during the optical writing, the secondary transfer member or the cleaning member is Since the secondary transfer member and the cleaning member do not contact the intermediate transfer member during the primary transfer, there is no contact / separation operation between the intermediate transfer member and the electrostatic latent image carrier. Horizontal stripes on the image due to the effect 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 position information on the intermediate transfer body, and when printing a color or monochrome image continuously, according to the size of the transfer paper to be output, Since the position information on the intermediate transfer member, which is the basis of the image forming process, is selected, the secondary transfer member and the cleaning member contact and separate from the intermediate transfer member during the primary transfer and the optical writing of the next print. This prevents the transfer of the intermediate transfer member and the electrostatic latent image carrier from being affected, prevents the occurrence of defects such as horizontal stripes on the image, and provides the most efficient number of continuous prints. (The number of prints per unit time) can be increased.

  The color image forming apparatus of the fourth means has a plurality of position information on the intermediate transfer body, and when printing a color or monochromatic image continuously, according to the size of the transfer paper to be output, The first position information after the primary transfer of the size of the transfer paper to be output is selected as the position information on the intermediate transfer body as a reference for the image forming process, so that the optical writing during the primary transfer and the next print is performed. Since the secondary transfer member and the cleaning member do not contact and separate from the intermediate transfer member during operation, it does not affect the driving of the intermediate transfer member and the electrostatic latent image carrier, and The number of prints during continuous printing (the number of prints per unit time) can be increased most efficiently without occurrence of defects such as streaks.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the illustrated examples.

FIG. 1 is a schematic configuration diagram of a full-color printer showing one configuration example of an image forming apparatus according to the present invention.
In the printer of FIG. 1, a belt-shaped photoconductor (photoconductor belt) 1 serving as an electrostatic latent image carrier is uniformly charged by a charging charger 4 and then a laser deflector such as a laser light source and a rotary polygon mirror. Scanning exposure is performed based on image information by a laser optical device 5 including various lenses, mirrors, and the like, and an electrostatic latent image is formed on the surface. Here, the image information to be exposed is monochromatic image information obtained by decomposing a desired full-color image into yellow, magenta, cyan, and black color information. The electrostatic latent image formed on the photoreceptor belt 1 is a rotary color developing device 6 having three developing units (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 respectively by a black developing device 7 which is a developing unit containing black toner provided separately from the toner, and an image of each color is formed on the photoreceptor belt 1. It is formed.

  Each of the color developing device 6 and the black developing device 7 includes a developing roller which comes close to or comes into contact with the photoreceptor belt 1 at a predetermined position, and develops a latent image on the photoreceptor belt 1 by non-contact development or contact development. Has the function of

In FIG. 1, reference numeral 10 denotes an intermediate transfer belt, which is an intermediate transfer member. The intermediate transfer belt 10 is provided between rotating rollers 11 and 12, and is rotated in a direction indicated by an arrow B in FIG. .
The photoreceptor belt 1 is bridged between the rotation rollers 2 and 3 and is rotated in the direction of arrow A in the figure by driving the rotation rollers, so that each color image formed on the photoreceptor belt 1 is The primary transfer bias brush 13 provided in the intermediate transfer belt 10 is provided for each of yellow, magenta, cyan, and black on the intermediate transfer belt 10 rotating in the direction of arrow B in FIG. When an appropriate voltage is applied, the images are sequentially superimposed and transferred (primary transfer). 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 to the transfer unit from the paper supply cassette 8 via the paper supply rollers 9a and the registration rollers 9b. Transfer (secondary transfer) is performed. After the transfer, the transfer paper is fixed by the fixing device 18 to complete a full-color image.

  In the drawing, reference numeral 15 denotes a waste toner collecting container including a cleaning blade 15A for cleaning the surface of the photoreceptor 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 includes: During image formation, it is kept at a position separated from the surface of the intermediate transfer belt 10, and is brought into pressure contact with the surface of the intermediate transfer belt 10 as shown in FIG. A mechanism is provided.

FIG. 2 shows an embodiment of a developing device relating to the color image forming apparatus of the present invention.
In the vicinity of the photoreceptor belt 1, a rotary (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 are arranged. In the rotary developing device 6, a casing 20 forming a rotating body is provided rotatably about a rotation center O, and the casing 20 is rotated in the direction of arrow C by a drive mechanism (not shown). The casing 20 has a shape that divides the developing device into three parts, thereby forming yellow, magenta, and cyan color developing units 22-Y, M, and C, respectively.

  FIG. 3 shows a state in which one developing unit 22Y in the color developing device 6 is at the developing position, and FIG. 4 is an enlarged view of only one developing unit 22Y. Each of the developing units 22-Y, M, and C is provided with a cylindrical developing roller 23-Y, M, and C as a developer conveying member. Each of the developing rollers 23-Y, M, and C is arranged such that a part thereof is exposed to the outside through an opening provided in the casing 20, and the casing 20 is moved in the direction of arrow C in FIG. To develop the electrostatic latent image 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. In each of the developing devices 22-Y, M, and C, toner of each color of yellow, magenta, and cyan is stored. The electrostatic latent images formed on the photoreceptor belt 1 are sequentially developed by selectively rotating to the developing position about the rotation center O. The developed images (toner images of each color) formed on the photoreceptor belt 1 are sequentially superimposed and transferred onto the intermediate transfer belt 10 as described above. A full-color image is formed by batch-transferring the images onto transfer paper.

  Although FIG. 4 shows only the configuration of the yellow developing unit 22Y, the configurations of the magenta and cyan developing units 22-M and C are the same. The developing roller 23Y (M, C) rotates at a position facing the photoreceptor belt 1 in the same direction as the moving direction of the photoreceptor belt 1 (direction of arrow A in the figure) with a predetermined linear velocity ratio. In the direction of arrow D in FIG. A supply roller 31Y (M, C) made of an elastic material such as foamed polyurethane is provided near the developing roller 23Y (M, C), and rubs with the developing roller 23Y (M, C) at a rubbing portion. The developing roller 23Y (M, C) rotates in the direction D so that the moving directions of the two rollers are the same in the rubbing portion, and the supply roller 31Y (M, C) rotates at a predetermined linear speed with the developing roller. It is provided so as to rotate in the E direction with a ratio. In the unit, a thin layer blade 32Y (M, C) made of an elastic material such as a stainless thin plate or urethane rubber having a thickness of about 0.1 mm has one end in contact with the developing roller 23Y (M, C). It is provided as follows. Further, a first toner conveying member (such as a coil screw) 33Y (M, C) for supplying toner from a toner storage unit (not shown) into the unit is provided in the toner conveying space 34Y (M, C) in the unit of the developing device. ) Is provided, and a second toner conveying member (coil screw or the like) 35Y (M, C) for collecting surplus toner in the unit into the toner container is provided, and the first and second toner conveying members 35Y (M, C) are 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 developing device in which a black toner is contained in a developing container 41, and the life of the developing device is replaced when the toner runs out. It is a developing device formed in. In the black developing device 7 as well, similarly to the developing devices 22-Y, M, and C of the color developing device 6, the developing roller 23 moves with respect to the photosensitive belt 1 at a predetermined linear velocity ratio in the moving direction of the photosensitive belt 1 (in the drawing). It is arranged opposite to the photoreceptor belt 1 so as to rotate in the same direction as the direction of arrow A). A supply roller 31 made of an elastic material such as foamed polyurethane is provided above the developing roller 23. The supply roller 31 rubs with the developing roller 23 in the rubbing portion, and moves in the same direction as the developing roller 23 in the rubbing portion. So as to rotate at a predetermined linear velocity ratio. Further, a thin layer blade 32 made of an elastic material such as a stainless steel plate or urethane rubber having a thickness of about 0.1 mm 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 stirring the toner near the thin layer blade 32 is provided, and a first roller for conveying and stirring the toner toward the supply roller 31 and the developing roller 23 is provided. An agitator 43 and a second agitator 44 are provided.
The black developing device 7 is pressed by a pressing unit (not shown) in a direction away from the photosensitive belt 1, and the rotation of the cam 45 causes the developing roller 23 to be brought into contact with or separated from the photosensitive belt 1. It has become.

  As described above, a configuration example of the color image forming apparatus according to the present invention has been described by taking a 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 of FIG. 1, and the components denoted by the same reference numerals are the same components. In the present embodiment, as shown in FIG. The length of the belt 10 is longer than that of the configuration of FIG. 1, and further, the peripheral length of the intermediate transfer belt 10 can be set to a maximum length of transfer paper that can be output, and the 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 photoreceptor 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 transfer paper length that can be output is A4 length 297 mm, and the length from the optical writing position 5A on the photoreceptor 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 rotation. Therefore, there is a time gap between the end of the primary transfer and the optical writing of the next plate without the temporal overlap between the primary transfer process and the optical writing process of the next plate. The contact and separation of the secondary transfer roller 14 to and from the intermediate transfer belt 10 and the contact and separation of the intermediate transfer belt cleaning member 16A to and from the intermediate transfer belt 10 can be performed in this time gap. By outputting one print every four rotations of the intermediate transfer belt with reference to one piece of position information 46 on the intermediate transfer belt 10, the number of prints in continuous time (the 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, first, the photosensitive belt 1 is driven, and at the same time, charging is performed by the charging charger 4. Next, an exposure step (optical writing) is performed by the laser optical device 5, and a yellow electrostatic latent image is formed on the photoreceptor belt 1. When the electrostatic latent image moves to the development position, development is performed by the yellow developing device 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 faces the developing position on the photosensitive belt 1. Further, an exposure step (optical writing) by the laser optical device 5 is performed so as to synchronize with the toner image on the intermediate transfer belt 10, and a magenta electrostatic latent image is formed on the photoreceptor belt 1, and the electrostatic latent image is formed. Development is performed in synchronization with the movement of the image to the development position. The magenta toner image is similarly overlaid and transferred onto the intermediate transfer belt 10 by applying a bias by the primary transfer bias brush 13. The steps up to this point are the same as those for the cyan of the third plate in FIG. 6, and the illustration of the image forming steps of the first and second plates is omitted in FIG.

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

  This timing chart is for continuous printing, and after the primary transfer of the fourth print (black) toner image of the previous print has all been completed, optical writing of the first print (yellow) of the next print is performed. As shown in FIG. 6, in the color image forming apparatus of 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 with the intermediate transfer belt 10 are performed on the first plate of the next print. This is performed before the start of (yellow) optical writing.

As described above, the contact operation of the secondary transfer roller 14 and the contact operation of the cleaning member 16A of the intermediate transfer belt 10 with the intermediate transfer belt 10 are performed after the completion of the primary transfer and the light of the first plate (yellow) of the next print. Performing before the start of writing does not affect the driving of the intermediate transfer belt 10 and the photoreceptor belt 1 during the primary transfer and the optical writing of the next print. No problems occur.
After the primary transfer of the first print (yellow) toner image of the next print is completed, optical writing of the second print (magenta) of the next print is performed. As shown in FIG. 6, in the color image forming apparatus of the present embodiment, 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 are performed in the second printing of the next print. This is performed before the start of (magenta) optical writing.

In this manner, 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 primary transfer of the first plate (yellow) of the next print is completed. This is performed before the start of optical writing of the second print (magenta) of the next print, thereby affecting the drive of the intermediate transfer belt 10 and the photosensitive belt 1 during the primary transfer and during the optical write of the next print. There is no problem such as horizontal stripes on the image.
Then, by outputting one print every four rotations of the intermediate transfer belt 10 with reference to one piece of position information 46 on the intermediate transfer belt 10, the number of prints during continuous operation (the number of prints per unit time) can be determined most efficiently. You can do much.

Next, a color image forming apparatus according to the second embodiment will be described with reference to FIG.
The configuration of the full-color printer shown in FIG. 7 is basically the same as that of FIG. 1, and the components denoted by the same reference numerals are the same components. In this embodiment, as shown in FIG. The belt 10 has a plurality of position information (for example, marks installed at equal intervals in the circumferential direction of the intermediate transfer belt) 46, and one of the position information is used as a reference (for example, a reference position). An image forming apparatus that detects information with position information detecting means such as a reflection type photo sensor and carries a plurality of color toner images on the intermediate transfer belt 10 in a superimposed manner. 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 are longer than the circumference of the intermediate transfer belt 10 and the circumference of the intermediate transfer belt. Is shorter than the sum of Forms.

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

  Here, FIG. 8 shows a schematic timing chart of the color image forming apparatus of the second means. In the timing chart of FIG. 8, the image forming operation portions of the first and second editions (yellow and magenta) are omitted, and the operation from the third edition (cyan) of optical writing is shown. In addition, the inverted triangle mark at the top in the figure indicates position information on the intermediate transfer belt that is used as a reference for the image forming process.

As shown in FIG. 8, in the present embodiment, during continuous printing of a color image, the reference position information 46 on the intermediate transfer belt 10 is delayed by one by one for each print, and the intermediate transfer belt 4 rotations + distance between position information Since one print is output every time, the primary transfer process of the fourth print (black) toner image of the previous print and the optical writing process of the first print (yellow) of the next print may overlap in time. Absent.
Further, as shown in FIG. 8, in the color image forming apparatus of 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 with the intermediate transfer belt 10 are the fourth operation 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 started.

  As described above, the contact operation of the secondary transfer roller 14 and the contact operation of the cleaning member 16A of the intermediate transfer belt 10 with the intermediate transfer belt 10 are performed after the completion of the primary transfer and for the first plate (yellow) of the next print. Performing before the start of optical writing does not affect the driving of the intermediate transfer belt 10 and the photoreceptor belt 1 during primary transfer and optical writing of the next print. Does not occur.

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 are performed at least after the optical writing process of the first plate (yellow) of the next print is completed. Is performed before the optical writing of the second version (magenta) of the next print is started.
That is, the influence of 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 on the driving of the intermediate transfer belt 10 and the photosensitive belt 1 is determined by an optical writing process. The influence on the primary transfer step is small, and therefore, at least the temporal overlap with the optical writing step is avoided.

  With this configuration, the intermediate transfer during the optical writing process and the primary transfer process is performed 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 with the intermediate transfer belt 10. Optical writing can be performed by eliminating the influence on the driving of the belt 10 and the photoreceptor belt 1, and by the operation of separating the secondary transfer roller 14 and the operation of separating the cleaning member 16A of the intermediate transfer belt 10 from the intermediate transfer belt 10. In this case, the influence on the driving of the intermediate transfer belt 10 and the photosensitive belt 1 can be eliminated, and under this condition, the circumference of the intermediate transfer belt can be minimized. (The number of prints per unit time) can be increased.

Next, a color image forming apparatus according to a third embodiment will be described with reference to FIG.
In the present embodiment, as shown in FIG. 7, the intermediate transfer belt 10 has a plurality of position information (for example, marks installed at equal intervals in the circumferential direction of the intermediate transfer belt) 46, and one of them An image forming apparatus that carries a plurality of color toner images in an overlapping manner on the intermediate transfer belt 10 based on the position information (for example, the position information serving as the reference is detected by position information detecting means such as a reflection type photo sensor). During continuous printing of color images, position information on the intermediate transfer belt, which is 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 position information 46 are provided at regular intervals on the intermediate transfer belt 10 to output a postcard size (length 148 mm), the reference (optical writing) of the image forming process of the next print is performed. As the position information on the intermediate transfer belt 10 to be (started), the position information two positions before the position information on the intermediate transfer belt 10 which is the reference (start of optical writing) of the image forming process of the previous print is selected.

  Here, FIG. 9 schematically shows a timing chart of the color image forming apparatus of the third means. In the timing chart of FIG. 9, the image forming operation portions of the first and second editions (yellow and magenta) are omitted, and the operation from the third edition (cyan) of optical writing is shown. In addition, the inverted triangle mark at the top in the figure indicates position information on the intermediate transfer belt that is used as a reference for the image forming process.

As shown in FIG. 9, at the time of continuous printing of a postcard size color image, the position information on the intermediate transfer belt as a reference (start of optical writing) of the image forming process of the next print is used for the image forming process of the previous print. The position information two positions 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 print (black) toner image of the previous print and the optical writing process of the first print (yellow) of the next print do not overlap with each other 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 with the intermediate transfer belt 10 are performed after the completion of the primary transfer and the first print (yellow) of the next print. By performing the transfer before the start of the transfer, the drive of the intermediate transfer belt 10 and the photoreceptor belt 1 is not affected during the primary transfer of the previous print and the optical writing of the next print, and the horizontal stripes are formed on the image. There is no such a problem. Then, the start of the image forming process for the next print can be advanced by twice the distance between the positional information, and as a result, 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, at the time of continuous printing of a postcard-size color image, immediately after the end of the optical writing process of the fourth print (black) of the previous print, the contact operation of the secondary transfer roller 14 and the cleaning member of the intermediate transfer belt 10 are performed. The contact operation of the intermediate transfer belt 10 of 16A is performed, and the subsequent positional information on the intermediate transfer belt 10 is used as a reference (start of optical writing) for the image forming process of the next print. As a result, the primary transfer process of the fourth print (black) toner image of the previous print and the optical writing process of the first print (yellow) of the next print do not overlap with each other 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 with the intermediate transfer belt 10 are performed after the completion of the primary transfer and the first print (yellow) of the next print. By performing the transfer before the start of the transfer, the drive of the intermediate transfer belt 10 and the photoreceptor belt 1 is not affected during the primary transfer of the previous print and the optical writing of the next print, and the horizontal stripes are formed on the image. There is no such a problem. Then, the start of the image forming process for the next print can be advanced twice as much as the distance between the pieces of position information. As a result, the number of continuous prints (the number of prints per unit time) can be increased most efficiently.

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

Further, in the third and fourth means, not only at the time of forming a color image but also at the time of continuous printing of a single color image, the position information on the intermediate transfer belt as a reference of the image forming process of the next print is similarly determined. Can be selected.
Further, in the embodiment, the length of the maximum transfer paper that can be output is set to A4 length, and the size of the output transfer paper is described as the postcard size (148 mm). 2 + paper interval (for example, 40 mm) = 460 mm, and a small output paper size such as A4 width and B5 length can be appropriately applied.

  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 and illustrates a state where each developing device is at 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 illustrated in FIG. 1 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. FIG. 1 is a schematic configuration diagram of a color image forming apparatus showing one 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. FIG. 11 is a schematic configuration diagram of a color image forming apparatus showing another embodiment of the present 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 illustrating another example of the image forming operation of the color image forming apparatus having the configuration illustrated in FIG. 7.

Explanation of reference numerals

1: Photoreceptor belt (electrostatic latent image carrier)
2, 3: photoreceptor belt rotating roller 4: charging 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 body)
11, 12: intermediate transfer belt rotating roller 13: primary transfer bias brush 14: transfer roller 15: waste toner collecting 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 for 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 1st agitator 44: 2nd agitator 45: cam 46: position information

Claims (4)

An electrostatic latent image carrier, a plurality of developing devices for developing latent images formed on the electrostatic latent image carrier with toners of different colors, and each color formed on the electrostatic latent image carrier Each toner image is sequentially transferred (primary transfer), and an intermediate transfer body that carries the toner images of the plurality of colors in an overlapping manner and a secondary transfer step of transferring the toner image on the intermediate transfer body onto transfer paper are performed. A color image forming apparatus having a transfer member that can be brought into and away from the intermediate transfer member, and a cleaning member that can be brought into and away from the intermediate transfer member for cleaning transfer residual toner on the intermediate transfer member.
A color 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 in a superimposed manner based on one of the position information. The color image forming apparatus according to claim 1,
The sum of the maximum length of transfer paper that can be output and the distance from the writing position on the electrostatic latent image carrier to the primary transfer position is longer than the intermediate transfer member circumference and is equal to the intermediate transfer member circumference. It is shorter than the sum of the distance between adjacent position information,
In continuous printing of a color image, a color image is output by delaying the reference position information on the intermediate transfer member by one for each print and outputting one print every four rotations of the intermediate transfer member + distance between position information. Forming equipment. The color image forming apparatus according to claim 1,
In continuous printing of color or monochromatic images, color image forming is characterized by selecting position information on an intermediate transfer body as a reference of an image forming process of a next print according to a size of a transfer paper to be output. apparatus. The color image forming apparatus according to claim 3,
The color image forming apparatus is characterized in that the position information to be selected is the first position information after the primary transfer of the size of the output transfer paper is completed.

Images