JP2008298835A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration in image quality when forming a monochrome image in an image forming apparatus which can form a monochrome image and a color image. <P>SOLUTION: A plurality of photoreceptor drums 21 are arranged corresponding to respective colors forming the color image and the photoreceptor drums are members which can carry electrostatic latent images on their surfaces. A plurality of developing units 22 supply developer for a color corresponding to each of the photoreceptor drums 21. An intermediate transfer belt 71 is an annular member arranged so as to be brought into contact with each of the photoreceptor drums 21. An intermediate transfer belt pressing mechanism 76 energizes the intermediate transfer belt 71 by a first energizing force to be in contact with all the photoreceptor drums 21. In addition, the intermediate transfer belt 71 is energized to the photoreceptor drum 21 for a specific color by a second energizing force which is greater than the first energizing force when forming an image for a specific monochrome image and the intermediate transfer belt 71 is separated from the photorecptor drum 21 which is other than the specific color photoreceptor drum 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of forming a monochrome image and a color image.

  An image forming apparatus includes an image forming unit capable of forming an image on a sheet based on image information, a sheet conveying unit that conveys the sheet to the image forming unit, a sheet storing unit that stores the sheet, and a sheet on which an image is formed. And a discharge part capable of discharging the gas. In this image forming apparatus, the paper is transported from the paper storage unit to the image forming unit by the paper transport unit. Then, an image is formed on the sheet based on the image information, and the sheet on which the image is formed is discharged from the discharge unit.

  The image forming unit includes an electrostatic image carrier on which an electrostatic latent image is formed on the surface based on image information, a developing device that supplies a developer to the electrostatic image carrier, an electrostatic latent image carrier, And an intermediate transfer belt for transferring the image formed on the paper to a sheet. In this image forming unit, an electrostatic latent image is formed on the electrostatic image carrier on the basis of image information, and a developer is supplied from the developing device to the electrostatic latent image carrier. After the developer image is formed on the electrostatic latent image carrier in this way, the developer image is transferred onto the sheet by the intermediate transfer belt.

  Here, some image forming apparatuses are capable of forming a color image in addition to a single color image. Some image forming apparatuses capable of forming a monochrome image and a color image have a plurality of electrostatic latent image carriers, which are arranged in a tandem manner, that is, arranged in a line. In such an apparatus, an intermediate transfer belt is disposed below the plurality of electrostatic latent image carriers, and an intermediate transfer belt pressing mechanism for bringing the intermediate transfer belt into contact with the electrostatic latent image carrier is provided. Yes.

This intermediate transfer belt pressing mechanism presses the intermediate transfer belt so that the intermediate transfer belt comes into contact with the electrostatic latent image carrier corresponding to a specific color (generally black) used when forming a monochrome image. A first pressing roller that presses the intermediate transfer belt so that the intermediate transfer belt contacts an electrostatic latent image carrier corresponding to other colors (colors other than black) at the time of color image formation, and at the time of monochrome image formation And a second pressing roller that moves so that the intermediate transfer belt is separated from the electrostatic latent image carrier (see Patent Document 1).
Japanese Patent Laid-Open No. 10-293437

  In the image forming apparatus described in Patent Document 1, the intermediate transfer belt is pressed toward the electrostatic latent image carrier by the first pressing roller and the plurality of second pressing rollers when forming a color image. In some cases, only the first pressing roller presses the intermediate transfer belt toward the electrostatic latent image carrier, so that when the monochrome image is formed, the pressing force of the intermediate transfer belt to the electrostatic latent image carrier is reduced. For this reason, the developer image on the electrostatic latent image carrier is not transferred to the intermediate transfer belt, and the image quality is likely to deteriorate due to the lack of characters.

  SUMMARY OF THE INVENTION An object of the present invention is to prevent a deterioration in image quality when a monochrome image is formed in an image forming apparatus capable of forming a monochrome image and a color image.

  An image forming apparatus according to claim 1 is an image forming apparatus capable of forming a single color image and a color image, and includes a plurality of electrostatic latent image carriers, a plurality of developing devices, an intermediate transfer belt, and an intermediate transfer. A belt pressing mechanism. The plurality of electrostatic latent image carriers are members that are arranged corresponding to the respective colors forming the color image and can carry the electrostatic latent image on the surface. The plurality of developing devices supply developers of colors corresponding to the respective electrostatic latent image carriers. The intermediate transfer belt is an annular member disposed so as to be in contact with each electrostatic latent image carrier. The intermediate transfer belt pressing mechanism urges the intermediate transfer belt with a first urging force so as to be in contact with all the electrostatic latent image carriers when forming a color image, and a specific color when forming a specific monochrome image. The intermediate transfer belt is urged to the electrostatic latent image carrier with a second urging force larger than the first urging force, and the intermediate transfer belt is separated from the electrostatic latent image carrier other than the electrostatic latent image carrier of the specific color. It is a mechanism to make.

  In this image forming apparatus, an electrostatic latent image is formed on each electrostatic latent image carrier based on image information, and a developer is supplied from the developing device to the electrostatic latent image. The image thus formed on the electrostatic latent image carrier is transferred to the intermediate transfer belt, and the image is transferred from the intermediate transfer belt to the paper. Here, the intermediate transfer belt is urged by the intermediate transfer belt pressing mechanism so as to come into contact with all the electrostatic latent image carriers when forming a color image. On the other hand, when a specific single color image is formed, the intermediate transfer belt is urged to the electrostatic latent image carrier of the specific color with an urging force equal to or higher than that of the color image formation, and other than the electrostatic latent image carrier of the specific color The intermediate transfer belt is separated from the electrostatic latent image carrier.

  Here, when forming a monochrome image, the intermediate transfer belt is urged against the electrostatic latent image carrier of a specific color with an urging force higher than that of forming a color image. The image is easily transferred to the intermediate transfer belt, and it is possible to prevent the image quality from being deteriorated when a monochrome image is formed.

  An image forming apparatus according to a second aspect is the image forming apparatus according to the first aspect, wherein the intermediate transfer belt pressing mechanism is a first pressing roller disposed to face the electrostatic latent image carrier of a specific color. A plurality of second pressing rollers arranged opposite to the electrostatic ray image carrier other than the electrostatic latent image carrier of the specific color, and the first pressing roller on the electrostatic latent image carrier side when forming a monochrome image. A first pressing roller moving mechanism for moving the image forming apparatus; and a separation mechanism for separating the plurality of second pressing rollers from the electrostatic latent image carrier when forming a monochrome image.

  In this image forming apparatus, when a monochrome image is formed, the first pressing roller is moved toward the electrostatic latent image carrier by the first pressing roller moving mechanism, and the second pressing roller is moved by the separation mechanism to the electrostatic latent image carrier. Get away from.

  The image forming apparatus according to claim 3 is the image forming apparatus according to claim 1, wherein the plurality of electrostatic latent image carriers are arranged in a line, and the first pressing roller moving mechanism and the separating mechanism are arranged. Supports the first pressure roller and the second pressure roller, and extends along the direction in which the plurality of electrostatic latent image carriers are arranged, and the rotation is attached to the frame and rotatably supports the frame. And a drive mechanism for rotating the frame about the rotation shaft as a fulcrum. The first pressure roller is disposed on the side of the row in which the plurality of second pressure rollers are arranged, and the first pressure roller and the plurality of second pressure rollers are disposed on the opposite side across the rotation shaft. Has been.

  In this image forming apparatus, a frame extends along a direction in which a plurality of electrostatic latent image carriers are arranged, and a first pressing roller and a second pressing roller are supported by the frame. The frame is rotated by the drive mechanism about the rotation axis as a fulcrum by the rotation axis. That is, at the time of color image formation, the frame is located at a predetermined rotation position. In this case, all the pressing rollers are pressed against the corresponding electrostatic latent image carrier via the intermediate transfer belt. On the other hand, at the time of monochromatic image formation, the frame rotates about the rotation axis, and the first pressing roller is moved to the corresponding electrostatic latent image carrier. By this rotation, the second pressing roller moves so that the intermediate transfer belt is separated from the electrostatic latent image carrier, and the first pressing roller moves the intermediate transfer belt to the electrostatic latent image carrier more than when forming a color image. Move to press with a strong force.

  The image forming apparatus according to claim 4 is the image forming apparatus according to claim 2 or 3, wherein the intermediate transfer belt support mechanism is disposed between the frame and each of the first pressing roller and the second pressing roller. And a biasing member that biases each pressing roller toward the opposing electrostatic latent image carrier.

  Here, the first pressing roller and the second pressing roller can be urged toward the electrostatic latent image carrier.

  According to the present invention, it is possible to prevent the image quality from being deteriorated when a monochrome image is formed in an image forming apparatus capable of forming a monochrome image and a color image.

1. Configuration FIG. 1 shows a color printer 1 which is an image forming apparatus according to an embodiment of the present invention. FIG. 1 is a schematic diagram for showing the arrangement of each component, and details of each part are omitted.

  The color printer 1 is connected to a computer (not shown) or the like, and is a device that can print a color image on paper based on image information transmitted from an external computer or the like.

  The color printer 1 includes an image forming unit 2 that forms an image based on image information, a paper transport unit 3 that transports a paper, a fixing unit 4 that fixes an image formed by the image forming unit 2 to the paper, A paper storage unit 5 that stores paper, a discharge unit 6 that discharges the paper to the top of the color printer 1, and a transfer device 7 that transfers an image to the paper are provided.

  The image forming unit 2 includes four toner image forming units 2a, 2b, 2c, and 2d for forming toner images of different colors. The four toner image forming units 2a to 2d are arranged in a row in the horizontal direction. As shown in FIGS. 1 and 2, the photosensitive drum 21, the developing device 22, the charging device 24, and the exposure are respectively provided. A device 25 and a cleaning device 26 are included. Here, the image forming unit 2a is a part for forming a black image, the image forming unit 2b is a part for forming a yellow image, and the image forming unit 2c is a part for forming a cyan image. The forming part 2d is a part for forming a magenta image.

  The photosensitive drum 21 is a member that has a toner image formed on the surface thereof and is rotatable around a rotation axis. The rotation axis of each photosensitive drum 21 extends in a direction perpendicular to the paper surface of FIG.

  The developing device 22 is a device for supplying toner to the photosensitive drum 21 and is disposed adjacent to the photosensitive drum 21. The developing device 22 has a developer storage space 221 for storing the developer therein, and includes a developing roller 222. The developing roller 222 is disposed to face the photosensitive drum 21, and is a member for supplying the developer in the developer storage space 221 to the photosensitive drum 21.

  The charging device 24 is a device for charging the surface of the photosensitive drum 21, and is disposed below the photosensitive drum 21 and adjacent to the photosensitive drum 21.

  The exposure device 25 is a portion that irradiates the photosensitive drum 21 with light based on the image information, and is disposed above the photosensitive drum 21 and at a position where light can be irradiated between the charging device 24 and the developing device 22. Has been.

  The cleaning device 26 is a device for cleaning toner remaining without being transferred to the photosensitive drum 21, and includes a cleaning roller 261 and a cleaning blade 262. Further, the cleaning device 26 is disposed on the side of the photosensitive drum 21 in the vicinity of the photosensitive drum 21. The cleaning roller 261 is a member that removes transfer residual toner on the surface of the photosensitive drum 21 to the inside of the apparatus, and is disposed in parallel with the rotation axis of the photosensitive drum 21. The cleaning blade 262 is close to the photosensitive drum 21. The cleaning blade 262 is a member for scraping the residual toner that has not been removed by the cleaning roller 261 from the photosensitive drum 21 and collecting it in the apparatus.

  The paper transport unit 3 is a part that transports the paper in the paper storage unit 5 in the order of the image forming unit 2, the fixing unit 4, and the discharge unit 6.

  The fixing unit 4 is a part for fixing the image formed on the sheet by the image forming unit 2, and includes a pressure roller 41 and a heating roller 42.

  The paper storage unit 5 includes a plurality of paper feed cassettes 51 that can store various types of paper. The paper storage unit 5 is disposed at the lower part of the color printer 1.

  The discharge unit 6 is a part for discharging a sheet having an image fixed on the surface thereof to the outside of the color printer 1 and is provided at the top.

2. Transfer Device The transfer device 7 is a device for transferring a toner image formed on the photosensitive drum 21 onto a sheet, and includes an intermediate transfer belt 71, a driving roller 72, a driven roller 73, and a first transfer roller. 74, a second transfer roller 75, and an intermediate transfer belt pressing mechanism 76.

  The intermediate transfer belt 71 is a member disposed below each of the toner image forming units 2 a to 2 d and is disposed so as to come into contact with each of the photosensitive drums 21. The intermediate transfer belt 71 is an endless belt, and is stretched around a driving roller 72, a driven roller 73, and a first transfer roller 74.

  The driving roller 72 is a roller for circulating the intermediate transfer belt 71, and is disposed in the vicinity of the toner image forming unit 2d. The drive roller 72 is connected to a motor (not shown) and is driven by this motor.

  The driven roller 73 is a roller that is rotated by the power of the driving roller 72 being transmitted through the intermediate transfer belt 71, and is disposed in the vicinity of the toner image forming unit 2a. Further, the driven roller 73 is urged away from the driving roller 72 by the first spring 73a, whereby the intermediate transfer belt 71 is stretched (a state where tension is applied to the intermediate transfer belt 71). Maintained. Specifically, a pair of bearings (not shown) that support the shaft of the driven roller 73 are movably supported with respect to the frame, and the pair of bearings are moved in the above-described direction by the first spring 73a. It is energized.

  The first transfer roller 74 is a roller for transferring an image on the intermediate transfer belt 71 to a sheet, and is disposed below the toner image forming portions 2b and 2c. The first transfer roller 74 is disposed inside the intermediate transfer belt 71.

  The second transfer roller 75 is a roller for transferring an image on the intermediate transfer belt 71 to a sheet, and is disposed at a position facing the first transfer roller 74 with the intermediate transfer belt 71 interposed therebetween.

  The intermediate transfer belt pressing mechanism 76 is a mechanism for pressing the intermediate transfer belt 71 toward the image forming unit 2, and includes a first pressing roller 761, three second pressing rollers 762, a coil spring 763, and a pressing A roller moving mechanism 764.

  The first pressing roller 761 is disposed at a position facing the photosensitive drum 21 of the toner image forming unit 2a with the intermediate transfer belt 71 interposed therebetween, and the intermediate transfer belt 71 in the vicinity of the toner image forming unit 2a is moved to the photosensitive drum. It is a member for pressing to 21 side.

  The second pressing roller 762 is disposed so as to face the photosensitive drums 21 of the toner image forming portions 2b, 2c, and 2d with the intermediate transfer belt 71 interposed therebetween, and the image formed on each photosensitive drum 21. Is a roller for transferring the toner image to the intermediate transfer belt 71. The two second pressing rollers 762 are arranged side by side on the side of the first pressing roller 761, and when forming a monochrome image, as shown in FIG. 2, the intermediate transfer belt 71 is moved by the pressing roller moving mechanism 764. Is moved so as not to contact the photosensitive drum 21.

  The coil spring 763 is disposed below the first pressing roller 761 and the second pressing roller 762, and is a member for pressing the first pressing roller 761 and the second pressing roller 762 toward the photosensitive drum 21 side.

  The pressing roller moving mechanism 764 is a mechanism for moving the first pressing roller 761 and the second pressing roller 762, and includes a frame 764a, a rotating shaft 764b, and a solenoid valve 764c as a driving mechanism. Yes. The frame 764a is a member that rotatably supports the first pressing roller 761 and the second pressing roller 762 and supports the lower end of each coil spring 763, and is along the direction in which the photosensitive drums 21 are arranged. It extends. Further, when forming a color image, the frame 764a is arranged so as to be parallel to the direction in which the photosensitive drums 21 are arranged (color image forming posture), as shown in FIG. 1, and forms a single color image. In this case, as shown in FIG. 2, the image forming unit 2a is disposed so as to be inclined so that the end on the image forming unit 2a side is located above the other end (monochromatic image forming posture). The rotation shaft 764b is a shaft that rotatably supports the frame 764a, and is disposed between the first pressing roller 761 and the second pressing roller 762. That is, the first pressing roller 761 and the three second pressing rollers 762 are arranged on the opposite side with the rotation shaft 764b interposed therebetween. The rotating shaft 764b is attached to the frame of the color printer 1. The solenoid valve 764c is provided at one end of the frame 764a, that is, at the end opposite to the rotation shaft 764b with the second pressing roller 762 interposed therebetween. More specifically, the tip of the rod of the solenoid valve 764c is connected to the bottom surface of one end of the frame 764a. With such a configuration, when the solenoid valve 764c is not energized, the rod of the solenoid valve 764c protrudes, and the frame 764a assumes a color image forming posture. When the solenoid valve 764c is energized, the solenoid valve The rod 764c is degenerated, and the frame 764a assumes a single-color image forming posture.

3. Operation A color image forming operation will be described.

  When image information is transmitted from an external computer or the like, an electrostatic latent image is formed on the photosensitive drum 21 based on the image information. Specifically, the surface of the photosensitive drum 21 is charged by the charging device 24, and light is irradiated by the exposure device 25 based on the image information, whereby an electrostatic latent image is formed on the photosensitive drum 21. . When the electrostatic latent image is formed on the photosensitive drum 21, the developer is supplied from the developing device 22 onto the photosensitive drum 21. At this time, the solenoid valve 764c of the pressing roller moving mechanism 764 is off, the rod protrudes, and as shown in FIG. 1, the frame 764a assumes a color image forming posture parallel to the direction in which the photosensitive drums 21 are arranged. ing. Here, the first pressing roller 761 and the second pressing roller 762 are pressed toward the photosensitive drum 21 by the coil spring 763 so that the intermediate transfer belt 71 is pressed against each photosensitive drum 21. In this state, a toner image is transferred from the photosensitive drum 21 to the intermediate transfer belt 71, and the toner image is conveyed to a position where the first transfer roller 74 and the second transfer roller 75 face each other as the intermediate transfer belt 71 circulates. Is done. At this time, the paper in the paper storage unit 5 is conveyed by the paper conveyance unit 3 between the first transfer roller 74 and the second transfer roller 75. The toner image on the intermediate transfer belt 71 is transferred onto a sheet by the first transfer roller 74 and the second transfer roller 75, and the sheet is conveyed to the fixing unit 4 by the sheet conveying unit 3. The toner image is fixed on the sheet by the fixing unit 4, and the sheet is discharged from the discharge unit 6.

  Next, an operation for forming a monochrome image will be described.

  As in the color image forming operation, image information is transmitted from an external computer or the like, and an electrostatic latent image is formed on the photosensitive drum 21 based on the image information. When the electrostatic latent image is formed on the photosensitive drum 21, a developer is supplied from the developing device 22 onto the photosensitive drum 21 to form a toner image. At this time, the solenoid valve 764c of the pressing roller moving mechanism 764 is ON and the rod is retracted, and as shown in FIG. 2, the toner image forming unit 2a side of the frame 764a is another toner image forming unit 2b, 2c, 2d. The monochromatic image forming posture is inclined so as to be positioned on the upper side. Here, the first pressing roller 761 is pressed toward the photosensitive drum 21 by the coil spring 763 so that the intermediate transfer belt 71 is pressed against the photosensitive drum 21. Here, since the plate-shaped member 764a is inclined, the first pressing roller 761 is pressed against the photosensitive drum 21 with a stronger pressing force than that at the time of color image formation. On the other hand, since the second pressing roller 762 moves downward, the intermediate transfer belt 71 is separated from the toner image forming portions 2b, 2c, 2d.

  Thereafter, similarly to the color image forming operation, the toner image is transferred from the photosensitive drum 21 to the intermediate transfer belt 71, and the first transfer roller 74 and the second transfer roller 75 face each other as the intermediate transfer belt 71 circulates. The toner image is conveyed to the position. At this time, the paper in the paper storage unit 5 is conveyed by the paper conveyance unit 3 between the first transfer roller 74 and the second transfer roller 75. The toner image on the intermediate transfer belt 71 is transferred onto a sheet by the first transfer roller 74 and the second transfer roller 75, and the sheet is conveyed to the fixing unit 4 by the sheet conveying unit 3. The toner image is fixed on the sheet by the fixing unit 4, and the sheet is discharged from the discharge unit 6.

  Here, since the first pressing roller 761 is pressed to the photosensitive drum 21 side more strongly at the time of monochromatic image formation than at the time of color image formation, the first pressing roller 761 has a stronger pressing force than at the time of color image formation. Thus, the intermediate transfer belt 71 is pressed against the photosensitive drum 21. For this reason, when the toner image on the photoconductive drum 21 is transferred to the intermediate transfer belt 71, it is possible to prevent the image quality from being deteriorated such as hollowing out.

4). Other Embodiments (a) In the above embodiment, the pressing force of the first pressing roller 761 toward the photosensitive drum 21 is changed by changing the posture of the plate-like member 764a. However, the present invention is not limited to this. For example, as shown in FIGS. 3 and 4, a first pressure roller support member 81 that supports the first pressure roller 761, a rack 82 and a pinion gear 83 that move the first pressure roller support member 81 up and down, A first pressing roller urging mechanism 8 including a coil spring 84 that urges the first pressing roller support member 81 toward the photosensitive drum 21 may be provided.

  Here, the first pressing roller support member 81 is a member for supporting the first pressing roller 761, and includes a roller supporting portion 811 formed so as to cover a lower portion of the first pressing roller 761, and a roller supporting portion. 811 and a rod-like portion 812 extending downward. The rack 82 has a horizontal plate portion 821 disposed below the rod-shaped portion 812 and a vertical plate portion 822 formed so as to extend downward from the end portion of the horizontal plate portion 821. The vertical plate portion 822 is formed with teeth that can be locked to the pinion gear 83. The pinion gear 83 is a member that is rotated by a motor (not shown). The coil spring 84 is a member disposed between the roller support portion 811 and the horizontal plate portion 821, and is a member for biasing the roller support portion 811 toward the photosensitive drum 21.

    In the first pressing roller urging mechanism 8, the vertical position of the rack 82 is set so that the first pressing roller 761 is urged toward the photosensitive drum 21 with the same urging force as that of the second pressing roller 762 during color image formation. In the color image formation, the vertical position of the rack 82 is adjusted so that the first pressing roller 761 is pressed toward the photosensitive drum 21 with a stronger force than in the monochrome image formation. That is, as shown in FIG. 4, when the monochromatic image is formed, the pinion gear 83 is rotated so that the rack 82 is positioned above the vertical position at the time of forming the color image. Here, each second pressing roller 762 is attached to a frame 85 that is rotatable around one end via an elastic member. When a monochrome image is formed, the intermediate transfer belt 71 is a photosensitive member as shown in FIG. It is rotated so as not to contact the drum 21.

  (B) In the above embodiment, the color printer 1 has been described. However, the present invention is not limited to this, and may be a copying machine, a multifunction machine, or the like.

1 is an overall schematic diagram of a color printer 1 when forming a color image. FIG. 1 is an overall schematic diagram of a color printer 1 when a single color image is formed. FIG. 3 is an overall schematic diagram of a color printer 1 according to another embodiment during color image formation. FIG. 3 is an overall schematic diagram of a color printer 1 according to another embodiment when a monochromatic image is formed.

Explanation of symbols

1 color printer 21 photosensitive drum 22 developing device 71 intermediate transfer belt 76 intermediate transfer belt pressing mechanism 761 first pressing roller 762 second pressing roller 763 coil spring 764 pressing roller moving mechanism 764a frame 764b rotating shaft

Claims (4)

An image forming apparatus capable of forming a monochrome image and a color image,
A plurality of electrostatic latent image carriers that are arranged corresponding to respective colors forming a color image and that can bear an electrostatic latent image on the surface;
A plurality of developing devices for supplying a developer of a color corresponding to each electrostatic latent image carrier;
An annular intermediate transfer belt disposed so as to be in contact with each of the electrostatic latent image carriers;
When forming a color image, the intermediate transfer belt is urged by a first urging force so as to be in contact with all the electrostatic latent image carriers, and when forming a specific monochrome image, The intermediate transfer belt is urged to the latent image carrier with a second urging force larger than the first urging force, and from the electrostatic latent image carrier other than the electrostatic latent image carrier of the specific color to the intermediate transfer belt. An intermediate transfer belt pressing mechanism for separating
An image forming apparatus. The intermediate transfer belt pressing mechanism is
A first pressing roller disposed to face the electrostatic latent image carrier of the specific color;
A plurality of second pressing rollers arranged to face the electrostatic ray image carrier other than the electrostatic latent image carrier of the specific color;
A first pressing roller moving mechanism for moving the first pressing roller toward the electrostatic latent image carrier when forming a monochrome image;
2. The image forming apparatus according to claim 1, further comprising a separation mechanism that moves the plurality of second pressing rollers to separate from the electrostatic latent image carrier when forming a monochrome image. The plurality of electrostatic latent image carriers are arranged in a line,
The first pressing roller moving mechanism and the separating mechanism are
A frame that supports the first pressing roller and the second pressing roller and extends along a direction in which the plurality of electrostatic latent image carriers are arranged;
A rotation shaft attached to the frame and rotatably supporting the frame;
A drive mechanism for rotating the frame about the rotation shaft as a fulcrum,
The first pressing roller is disposed on a side of a row in which a plurality of the second pressing rollers are arranged,
The first pressing roller and the plurality of second pressing rollers are disposed on the opposite sides with the rotation shaft interposed therebetween,
The image forming apparatus according to claim 1. The intermediate transfer belt support mechanism is
A biasing member is further disposed between the frame and each of the first and second pressing rollers, and biases the pressing rollers toward the opposing electrostatic latent image carrier. ,
The image forming apparatus according to claim 2.

Images