JP5393006B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a transfer device and an image forming apparatus, and more particularly, to a transfer device for transferring an image carried on a plurality of image carriers to a sheet and an image forming apparatus including the transfer device.

  An image forming apparatus capable of forming a color image is formed on a plurality of image carriers that can carry an electrostatic latent image, a developing device that can supply a developer to each image carrier, and each image carrier. The image forming apparatus includes a transfer member for transferring the developer image to a sheet, a sheet conveying unit that conveys a sheet on which an image can be formed, and a discharge unit that discharges the sheet on which the image is formed. In this image forming apparatus, a developer is supplied from the developing device to the electrostatic latent image carried on the image carrier. The developer image formed on the image carrier is transferred to a transfer member, and transferred from the transfer member to a sheet conveyed by a sheet conveying unit.

Here, in order to prevent developer leakage, the image carrier and the developing device are arranged side by side on the lower side of the transfer member, and the sheet is discharged from the lower side of the transfer member to the outside through the side of the transfer member. There is an image forming apparatus having a configuration (see Patent Document 1). In this image forming apparatus, a developer is supplied from the developing device to the image carrier on which the electrostatic latent image is formed, and a developer image is formed on the image carrier. The image formed on the image carrier is transferred while being sequentially superimposed on the transfer member, and a color image is formed on the transfer member. Then, this color image is transferred from the transfer member to the sheet, and the sheet is discharged to the outside.
JP 2007-41366 A

  In the image forming apparatus described in Patent Document 1, since the developing device and the image carrier are provided below the transfer member, the image cannot be transferred onto the sheet below the transfer member. For this reason, it is necessary to transport the paper to the side or above the transfer member. In this case, since the sheet has a bent conveyance path, it is difficult to use a thick sheet, and it is necessary to convey the sheet upward against the gravity because it has a bent conveyance path. Paper jams are likely to occur when transporting.

  Further, since there are minute irregularities on the surface of the paper, if a rigid body that is not easily elastically deformed is used as at least the surface of the transfer member, the transfer accuracy decreases. For this reason, in the conventional image forming apparatus, at least the surface of the transfer member is formed of an elastic member. However, when the transfer member is formed of an elastic member, the transfer member easily expands and contracts in its moving direction, or easily expands and contracts due to contact with the image carrier, and images are sequentially superimposed from a plurality of image carriers. When transferring to the transfer member, there is a possibility that image quality deterioration such as transfer deviation may occur.

  An object of the present invention is to prevent a decrease in printing speed due to an increase in a paper conveyance path.

  Another object of the present invention is to suppress deterioration in image quality due to elastic deformation of the transfer member.

The image forming apparatus according to the present invention is an image forming apparatus for transferring a supported image into a plurality of image bearing members to the sheet, and includes an intermediate transfer member, and the intermediate transfer roller, the. The intermediate transfer member transfers images from a plurality of image carriers. The intermediate transfer roller transfers an image from the intermediate transfer member and transfers the transferred image onto a sheet.

  In this image forming apparatus, an image is transferred from a plurality of image carriers to a transfer member, and the image is transferred from the transfer member to an intermediate transfer roller. Thereafter, the image is transferred from the intermediate transfer roller to the sheet.

  Here, for example, by arranging the intermediate transfer roller between the paper feed unit and the paper discharge unit arranged linearly with the paper feed unit, the paper transport path can be configured linearly, As a result, it is possible to make it difficult for paper conveyance errors such as paper jams to occur.

The image forming apparatus according to the present invention is the image forming apparatus , and the surface of the intermediate transfer roller can be elastically deformed.

The image forming apparatus according to the present invention is the image forming apparatus , wherein the intermediate transfer member is an annular belt member having higher rigidity than the surface of the intermediate transfer roller.

  Here, the intermediate transfer member can be made to be more rigid than the conventional intermediate transfer member to be difficult to elastically deform. For this reason, when transferring images from a plurality of image carriers to the intermediate transfer member, it is possible to accurately superimpose images and to prevent deterioration in image quality.

An image forming apparatus according to the present invention includes an image carrier, a developing device, an intermediate transfer member, an intermediate transfer roller, and a paper transport unit. The plurality of image carriers are members capable of carrying images. The plurality of developing devices are devices capable of supplying a developer to each of the plurality of image carriers. The intermediate transfer member is a member provided in contact with a plurality of image carriers. The intermediate transfer roller is a member whose surface is elastically deformed by transferring an image from the intermediate transfer member. The paper transport unit transports the paper so as to contact the intermediate transfer roller.

  In this image forming apparatus, an electrostatic latent image is formed on an image carrier based on image information, and a developer is supplied to the electrostatic latent image from a developing device. The developer images on the image carrier are sequentially transferred to the intermediate transfer member, and the images are superimposed on the intermediate transfer member to form a developer image. Thereafter, the developer image is transferred from the intermediate transfer member to the intermediate transfer roller, and the developer image is transferred from the intermediate transfer roller to the sheet conveyed by the sheet conveying unit.

  Here, the sheet transfer path can be made linear by arranging the intermediate transfer roller, for example, between the sheet feeding unit and the sheet discharging unit arranged on a straight line with the sheet feeding unit. The transport distance of the transport path can be shortened. As described above, by disposing the intermediate transfer roller at an appropriate position, it is possible to shorten the paper conveyance path and to prevent the printing speed from being lowered.

The image forming apparatus according to the present invention is the image forming apparatus, wherein the intermediate transfer member is an annular belt member having higher rigidity than the surface of the intermediate transfer roller.

  Here, the intermediate transfer member can be made to be more rigid than the conventional intermediate transfer member, so that it is difficult to be elastically deformed. For this reason, when transferring images from a plurality of image carriers to the intermediate transfer member, it is possible to accurately superimpose images and to prevent deterioration in image quality.

The image forming apparatus according to the present invention is the image forming apparatus, wherein the plurality of image carriers and developing devices are arranged side by side along an oblique direction so that positions in the height direction are gradually different. The intermediate transfer member is formed to extend in an oblique direction. The intermediate transfer roller is in contact with one end in the extending direction of the intermediate transfer belt.

  Here, since the intermediate transfer roller is disposed at one end in the extending direction of the intermediate transfer member, and the intermediate transfer member is disposed obliquely, the intermediate transfer roller can be easily disposed in the vicinity of the sheet conveying unit. .

The image forming apparatus according to the present invention is the image forming apparatus, wherein a plurality of image carriers and developing devices are arranged side by side along the lateral direction. The intermediate transfer member is formed to extend in the lateral direction. The intermediate transfer roller is in contact with one end in the lateral direction of the intermediate transfer member from the lower side or the upper side.

The image forming apparatus according to the present invention is the above-described image forming apparatus, and the paper transport unit is formed substantially horizontally.

  Here, printing can be performed at high speed.

  According to the present invention, it is possible to prevent a decrease in printing speed due to a long paper conveyance path. In addition, the intermediate transfer member can be made more rigid and less elastically deformed as compared with the prior art, thereby suppressing deterioration in image quality.

<First Embodiment>
Hereinafter, an embodiment of an image processing apparatus of the present invention will be described based on the drawings. For convenience of explanation, the position and size of the members are drawn with emphasis as appropriate in the drawings. In the following embodiments, a printer will be described as an example of the image processing apparatus of the present invention, but the present invention is not limited to this. That is, the image processing apparatus of the present invention only needs to include an image forming unit, and may be a so-called multi-function peripheral (MFP) having a function as a copying machine or a facsimile machine or only a copying function. Specific configurations of these members described below, other members, and the like can be appropriately changed.

1. Overall Configuration A schematic configuration of a color printer 1 as an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a front view showing a main configuration of the color printer 1.

  The color printer 1 transfers a toner image formed by the tandem image forming unit 12 that forms a toner image based on image data, a paper storage unit 13 that stores paper, and the image forming unit 12 onto the paper. The transfer unit 14, the fixing unit 15 that fixes the transferred toner image on the paper, the discharge unit 16 that discharges the fixed paper, and the paper transport that transports the paper from the paper storage unit 13 to the discharge unit 16. Mainly provided with a portion 17.

  The image forming unit 12 includes image forming units FY, FM, FC, and FB respectively corresponding to yellow (Y), magenta (M), cyan (C), and black (Bk) colors.

  Four image forming units FY, FM, FC, and FB are arranged side by side in the lateral direction below an intermediate transfer belt described later. Note that the order of arrangement of the image forming units FY, FM, FC, and FB is not limited to this, but this arrangement is preferable in consideration of the influence of the color mixture on the completed image. The image forming units FY, FM, FC, and FB include a photosensitive drum 110 as an electrostatic latent image carrier, a charger 111 as a charging device, an LED exposure device 112 as an exposure device, and a liquid developing device 113. And a drum cleaning device 114 and a charge removal device 115. The configuration of each image forming unit is the same.

  The photosensitive drum 110 is a member on which an electrostatic latent image is formed based on image information, and can carry a toner image including toner charged on the surface thereof (charged to positive polarity in the present embodiment). The photosensitive drum 110 is a member that can rotate counterclockwise as indicated by an arrow in FIG.

  The charger 111 is a device that can uniformly charge the surface of the photosensitive drum 110.

  The LED exposure device 112 has an LED light source, and can irradiate the charged surface of the photosensitive drum 110 with light corresponding to image data, thereby forming an electrostatic latent image on the surface of the photosensitive drum 110.

  The liquid developing device 113 is for supplying a liquid developer (toner) to the photosensitive drum 110, and includes a developing roller 113a, a supply roller 113b, a support roller 113c, a developer supply member 113d, and a development roller. An agent removing blade 113e, a developer charging device 113f, and a doctor blade 113g are provided. The developing roller 113a is disposed so as to contact the photosensitive drum 110. The supply roller 113b is for supplying the liquid developer to the developing roller 113a, and is in contact with the lower part of the developing roller 113a. The support roller 113c is a member for supporting the liquid developer together with the supply roller 113b, and is arranged so that the outer peripheral surface is in contact with the supply roller 113b. The tip of a doctor blade 113g is in contact with the supply roller 113b. The layer thickness of the liquid developer carried on the supply roller 113b to be supplied to the developing roller 113a by the doctor blade 113g is regulated to a predetermined value. The developer supply member 113d is a member for supplying a liquid developer having a toner concentration adjusted to a specified range in the vicinity of a contact portion between the supply roller 113b and the support roller 113c. The developer removing blade 113e is a member for removing the liquid developer remaining on the developing roller 113a without being supplied to the photosensitive drum 110, and scrapes off the liquid developer on the developing roller 113a. The developer charging device 113f is a device for charging the toner in the liquid developer carried on the developing roller 113a, and is disposed in the vicinity of the developing roller 113a.

  The drum cleaning device 114 is a device for cleaning the developer remaining on the photosensitive drum 10 without being transferred from the photosensitive drum 110 to the later-described intermediate transfer belt, and includes a residual developer conveying screw 114a and a drum cleaning device. And a blade 114b. The residual developer conveying screw 114 a is a member for conveying the residual developer scraped off by the drum cleaning blade 114 b and stored in the drum cleaning device 114 to the outside of the drum cleaning device 114. Is arranged. The drum cleaning blade 114 b is in sliding contact with the surface of the photosensitive drum 110 and is a member for scraping off the developer remaining on the surface of the photosensitive drum 110. The drum cleaning blade 114b is a plate-like member extending in the direction in which the photosensitive drum 110 extends.

  The neutralization device 115 includes a light source. After the developer is removed by the drum cleaning blade 114b, the surface of the photosensitive drum 110 is neutralized by light from the light source to prepare for the next image formation.

  The paper storage unit 13 is a part for storing paper for fixing a toner image, and is disposed on the side of the color printer 1. In addition, the paper storage unit 13 includes a paper feed cassette 131 that stores paper. The paper feed cassette 131 is provided with a paper feed unit 132 to the paper transport unit 17 at the upper end.

  The transfer unit 14 is a part that transfers a toner image formed on the photosensitive drum 110 to a sheet, and includes an intermediate transfer belt 141, a belt cleaning device 142, a squeeze roller 143, an image density detection sensor 144, A primary transfer roller 145, a first roller 146, a second roller 147, an intermediate transfer roller 148, and a counter roller 149 corresponding to each image forming unit are provided.

  The intermediate transfer belt 141 is a member to which a developer image is transferred from the plurality of photosensitive drums 110 and is disposed on the upper side of each photosensitive drum 110. Here, the intermediate transfer belt 141 is driven to rotate clockwise as indicated by an arrow in FIG. Further, the intermediate transfer belt 141 is an annular member and is stretched around the first roller 146 and the second roller 147. Further, the intermediate transfer belt 141 is made of a material that hardly undergoes elastic deformation, for example, polyimide.

  The belt cleaning device 142 is a device for cleaning the surface of the intermediate transfer belt 141, and is disposed in the vicinity of the second roller 147. The belt cleaning device 142 includes a belt cleaning blade 142a and a residual developer container 142b. The belt cleaning blade 142 a is a member that is in contact with the surface of the intermediate transfer belt 141, and scrapes the residual developer remaining on the surface of the intermediate transfer belt 141 without being transferred to the intermediate transfer roller 148. The residual developer storage container 142b is a container for storing the residual developer scraped by the belt cleaning blade 142a, and supports the belt cleaning blade 142a.

  The squeeze roller 143 is a roller for removing the carrier liquid of the image at the time of calibration, and is provided so as to contact the intermediate transfer belt 141.

  The image density detection sensor 144 is a sensor for detecting the toner density of the image transferred to the intermediate transfer belt 141, and is a member disposed between the intermediate transfer belt 141 and the paper transport unit 17.

  The primary transfer roller 145 is a roller used at the time of primary transfer, and is disposed so as to contact the back surface of the portion of the intermediate transfer belt 141 that is in contact with the photosensitive drum 110. The primary transfer roller 145 is a roller having a smaller diameter than the photosensitive drum 110.

  The first roller 146 is a roller provided near the discharge unit 16 and supports the intermediate transfer belt 141 together with the second roller 147.

  The second roller 147 is a roller disposed in the vicinity of the sheet storage unit 13 and is disposed to face the first roller 146.

  The intermediate transfer roller 148 is a roller for transferring the developer image on the intermediate transfer belt 141 to a sheet, and is formed of a member whose surface can be elastically deformed. That is, the intermediate transfer roller 148 is formed of a material that at least has a surface that is more elastically deformed than the intermediate transfer belt 141. Further, the intermediate transfer roller 148 is disposed so as to come into contact with the intermediate transfer belt 141 from above, and a developer image (color image) that is primarily transferred and overlaid on the intermediate transfer belt 141 is temporarily transferred to the intermediate transfer roller 148. After being transferred and held on the intermediate transfer roller 148, the developer image can be transferred onto the sheet conveyed by the sheet conveying unit 17. Further, the intermediate transfer roller 148 is provided with a predetermined nip between the intermediate transfer belt 141. That is, the intermediate transfer belt 141 is elastically deformed. The intermediate transfer roller 141 is a member that can rotate counterclockwise as shown by an arrow in FIG.

  The opposing roller 149 is a roller disposed so as to face the intermediate transfer roller 148, and is a roller used for secondary transfer together with the intermediate transfer roller 148 to transfer the developer image of the intermediate transfer roller 148 onto a sheet. It is.

  The fixing unit 15 is a part that fixes the toner image on the paper, and is disposed between the discharge unit 16 and the position where the intermediate transfer roller 148 and the opposing roller 149 face each other. In addition, the fixing unit 15 includes a heating roller 151 that is in contact with the toner image transferred to the paper, and a pressure roller 152 that is disposed to face the heating roller 151.

  The discharge unit 16 is a part from which the sheet on which the toner image is fixed by the fixing unit 15 is discharged, and is disposed on the side of the color printer 1.

  The paper transport unit 17 is a part that transports the paper to the paper storage unit 13, the fixing unit 15, and the discharge unit 16 in the direction indicated by the arrow in FIG. It is provided horizontally. The paper transport unit 17 includes a plurality of roller pairs 17a and a transport belt 17b for transporting paper, and can transport the paper to contact the intermediate transfer roller 148.

2. Operation Next, an image forming operation of the wet color printer 1 will be described with reference to FIG.

  The color printer 1 that has received an image formation instruction from a personal computer (PC) connected to the color printer 1 converts the toner images of each color corresponding to the image data that has received the creation instruction into image forming units FY, FM, FC, and FB. It forms using. Specifically, an electrostatic latent image based on image data is formed on the photosensitive drum 110, and toner is supplied to the electrostatic latent image from the liquid developing device 113. The images formed by the image forming units 12 in this way are sequentially transferred to the intermediate transfer belt 141 and are superimposed on the intermediate transfer belt 141 to form a color toner image. The color toner image is conveyed to a position where the intermediate transfer belt 148 and the intermediate transfer belt 141 come into contact with the circulation of the intermediate transfer belt 141, and is transferred from the intermediate transfer belt 141 to the intermediate transfer roller 148. At this time, the sheet is taken out from the sheet storage unit 13 by the sheet feeding unit 132, and the sheet is conveyed to a portion where the opposing roller 149 and the intermediate transfer roller 148 are in contact with each other. Is transferred from the intermediate transfer roller 148 to the sheet.

  The sheet on which the color toner image has been transferred is further conveyed to the fixing unit 15 where the color toner image is fixed on the sheet by heat and pressure. Further, the paper is discharged outside the wet color printer 1 by the discharge unit 16. The toner remaining on the intermediate transfer belt 141 after the secondary transfer is removed from the intermediate transfer belt 141 by the belt cleaning device 142 of the intermediate transfer belt 141.

  Here, since the intermediate transfer belt 141 is formed of a member that is not easily elastically deformed, when the image is transferred from the photosensitive drum 110, the overlapping of the images is not easily displaced. Further, since the intermediate transfer belt 141 and the sheet are in contact with the intermediate transfer roller 148 with a predetermined nip width, when transferring from the intermediate transfer belt 141 to the intermediate transfer roller 148 and when transferring from the intermediate transfer roller 148 to the sheet. It is possible to prevent the transfer accuracy from being lowered. Furthermore, since the paper transport path 17 can be made substantially horizontal, printing can be performed at high speed without being jammed.

Second Embodiment
1. Overall Configuration A schematic configuration of a color printer 2 as an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 2 is a front view showing the main configuration of the color printer 2.

  The color printer 2 includes an image forming unit 22 that forms a toner image based on image data, a paper storage unit 23 that stores paper, and a transfer unit 24 that transfers a toner image formed by the image forming unit 22 onto the paper. A second fixing unit 25 that fixes the transferred toner image on the paper, a discharge unit 26 that discharges the fixed paper, and a paper transport unit that transports the paper from the paper storage unit 23 to the discharge unit 26. 27 mainly.

  The image forming unit 22 includes four image forming units FY, FM, FC, and FB corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (Bk).

  The image forming units FY, FM, FC, and FB are disposed between an intermediate transfer belt 241 of the transfer unit 24 and a paper transport unit 27, which will be described later, and are in order of the image forming units FY, FM, FC, and FB. They are arranged in an oblique direction so that the height position gradually changes. Note that the order of arrangement of the image forming units FY, FM, FC, and FB is not limited to this, but this arrangement is preferable in consideration of the influence of the color mixture on the completed image. The image forming units FB, FC, FM, and FY include a photosensitive drum 210 as an electrostatic latent image carrier, a charger 211 as a charging device, an LED exposure device 212 as an exposure device, and a liquid developing device 213. , A drum cleaning device 214 and a static eliminator 215. The configuration of each image forming unit is the same.

  The photosensitive drum 210 is a member on which an electrostatic latent image is formed based on image information, and can carry a toner image including toner charged on the surface thereof (charged positively in the present embodiment). The photosensitive drum 210 is a member that can rotate counterclockwise as indicated by an arrow in FIG.

  The charger 211 is a device that can uniformly charge the surface of the photosensitive drum 210.

  The LED exposure device 212 has an LED light source, and can irradiate the charged surface of the photosensitive drum 210 with light corresponding to image data to form an electrostatic latent image on the surface of the photosensitive drum 210.

  The liquid developing device 213 is for supplying a liquid developer (toner) to the photosensitive drum 210, and includes a developing roller 213a, a supply roller 213b, a support roller 213c, a developer supply member 213d, and a development. An agent removing blade 213e, a developer charging device 213f, and a doctor blade 213g are provided. The developing roller 213a is disposed so as to contact the photosensitive drum 210. The supply roller 213b is for supplying a liquid developer to the developing roller 213a, and is in contact with the lower part of the developing roller 213a. The support roller 213c is a member for supporting the liquid developer together with the supply roller 213b, and is arranged so that the outer peripheral surface is in contact with the supply roller 213b. The tip of a doctor blade 213g is in contact with the supply roller 213b. The doctor blade 213g regulates the layer thickness of the liquid developer carried on the supply roller 213b to be supplied to the development roller 213a to a predetermined value. The developer supply member 213d is a member for supplying a liquid developer having a toner concentration adjusted to a specified range in the vicinity of a contact portion between the supply roller 213b and the support roller 213c. The developer removing blade 213e is a member for removing the liquid developer remaining on the developing roller 213a without being supplied to the photosensitive drum 210, and scrapes off the liquid developer on the developing roller 213a. The developer charging device 213f is a device for charging the toner in the liquid developer carried on the developing roller 213a, and is disposed in the vicinity of the developing roller 213a.

  The drum cleaning device 214 is a device for cleaning the developer remaining without being transferred from the photosensitive drum 210 to the intermediate transfer belt 241, and includes a residual developer conveying screw 214a and a drum cleaning blade 214b. Yes. The residual developer conveying screw 214 a is a member for conveying the residual developer scraped by the drum cleaning blade 214 b and stored in the drum cleaning device 214 to the outside of the drum cleaning device 214. Is arranged. The drum cleaning blade 214 b is in contact with the surface of the photosensitive drum 210 and is a member for scraping off the developer remaining on the surface of the photosensitive drum 210. The drum cleaning blade 214b is a plate-like member extending in the direction in which the photosensitive drum 210 extends.

  The static eliminator 215 includes a light source. After the developer is removed by the drum cleaning blade 214b, the surface of the photosensitive drum 210 is neutralized with light from the light source to prepare for the next image formation.

  The paper storage unit 23 is a part for storing paper for fixing a toner image, and is disposed on the side of the color printer 2. In addition, the paper storage unit 23 includes a paper feed cassette 231 that stores paper. The paper feed cassette 231 is provided with a paper feed unit 232 to the paper transport unit 27 at the upper end.

  The transfer unit 24 is a part that transfers a toner image formed on the photosensitive drum 210 to a sheet, and includes an intermediate transfer belt 241, a belt cleaning device 242, and a primary transfer roller 243 corresponding to each image forming unit. A first roller 244, a second roller 245, an intermediate transfer roller 246, and a counter roller 247.

  The intermediate transfer belt 241 is a member to which a developer image is transferred from the plurality of photosensitive drums 210 and is disposed on the upper side of each photosensitive drum 210. In other words, the image forming units FB, FC, FM, FY are arranged in an oblique direction so that the height position is gradually increased, so that the image forming units are arranged obliquely. Further, the intermediate transfer belt 241 is an annular member and is stretched around the first roller 244 and the second roller 245. Here, the intermediate transfer belt 241 is driven to rotate clockwise as indicated by an arrow in FIG. Further, the intermediate transfer belt 241 is made of a material that hardly undergoes elastic deformation, for example, polyimide.

  The belt cleaning device 242 is a device for cleaning the surface of the intermediate transfer belt 241 and is disposed in the vicinity of the second roller 245. The belt cleaning device 242 includes a belt cleaning blade 242a and a residual developer container 242b. The belt cleaning blade 242 a is a member that is in contact with the surface of the intermediate transfer belt 241, and scrapes the residual developer remaining on the surface of the intermediate transfer belt 241 without being transferred to the intermediate transfer roller 246. The residual developer storage container 242b is a container for storing the residual developer scraped by the belt cleaning blade 242a, and supports the belt cleaning blade 242a.

  The primary transfer roller 243 is a member used for primary transfer, and is disposed so as to contact the back surface of the portion of the intermediate transfer belt 241 that is in contact with the photosensitive drum 210. The primary transfer roller 243 is a roller having a smaller diameter than the photosensitive drum 210.

  The first roller 244 is disposed in the vicinity of the photosensitive drum 210 of the toner image forming unit FY, and supports the intermediate transfer belt 241 together with the second roller 245.

  The second roller 245 is disposed in the vicinity of the toner image forming unit FB, and is disposed to face the first roller 244. Further, the second roller 245 is disposed at a position higher than the first roller 244.

  The intermediate transfer roller 246 is a roller for transferring the developer image on the intermediate transfer belt 241 to a sheet, and is formed of a member whose surface can be elastically deformed. The intermediate transfer roller 246 is disposed so as to come into contact with the intermediate transfer belt 241 from the lower side, and a developer image (color image) primarily transferred and overlaid on the intermediate transfer belt 241 is temporarily transferred to the intermediate transfer roller 246. After being transferred to the intermediate transfer roller 246, the developer image can be transferred onto the sheet conveyed by the sheet conveying unit 27. Further, the intermediate transfer roller 246 is provided with a predetermined nip between the intermediate transfer belt 241, that is, is elastically deformed by the intermediate transfer belt 241. The intermediate transfer roller 246 is a member that can rotate counterclockwise as indicated by an arrow in FIG.

  The opposing roller 247 is a roller disposed so as to face the intermediate transfer roller 246, and is used for transferring the developer image of the intermediate transfer roller 246 onto a sheet, that is, for performing secondary transfer together with the intermediate transfer roller 246. Laura. A voltage having a polarity opposite to that of the toner is applied to the counter roller 247 at the time of image transfer, and the toner image is transferred onto a sheet.

  The fixing unit 25 is a part for fixing the toner image on the sheet, and is disposed between the discharge unit 26 and a position where the intermediate transfer roller 246 and the opposing roller 247 face each other. The fixing unit 25 includes a heating roller 251 that is in contact with the toner image transferred onto the paper, and a pressure roller 252 that is disposed to face the heating roller 251.

  The discharge unit 26 is a portion from which the sheet on which the toner image is fixed by the fixing unit 25 is discharged, and is disposed on the side of the color printer 2.

  The paper transport unit 27 is a part that transports the paper in the direction indicated by the arrow in FIG. 2 to the paper storage unit 23, the fixing unit 25, and the discharge unit 26. It is provided horizontally. The paper transport unit 27 includes a plurality of roller pairs 271 for transporting paper, and can transport the paper to contact the intermediate transfer roller 246.

2. Operation Next, an image forming operation of the wet color printer 2 will be described with reference to FIG.

  Upon receiving an image formation instruction from a personal computer (PC) connected to the wet color printer 2, the color printer 2 converts the toner images of the respective colors corresponding to the image data received with the creation instruction into image forming units FY, FM, FC. , FB. Specifically, an electrostatic latent image based on image data is formed on the photosensitive drum 210, and toner is supplied to the electrostatic latent image from the liquid developing device 213. The images formed by the image forming units 22 in this way are sequentially transferred to the intermediate transfer belt 241 and are superimposed on the intermediate transfer belt 241 to form a color toner image. The color toner image is conveyed to a position where the intermediate transfer belt 246 and the intermediate transfer belt 241 come into contact with the circulation of the intermediate transfer belt 241, and is transferred from the intermediate transfer belt 241 to the intermediate transfer roller 246. At this time, the sheet is conveyed from the sheet storage unit 23 to a portion where the opposing roller 247 and the intermediate transfer roller 246 are in contact, and the image is transferred from the intermediate transfer roller 246 to the sheet as the intermediate transfer roller 246 rotates.

  The sheet on which the color toner image has been transferred is further conveyed to the fixing unit 25 where the color toner image is fixed on the sheet by heat and pressure. Further, the paper is discharged outside the wet color printer 2 by the discharge unit 26. The toner remaining on the intermediate transfer belt 241 after the secondary transfer is removed from the intermediate transfer belt 241 by the belt cleaning device 242 of the intermediate transfer belt 241.

  Here, since the intermediate transfer belt 241 is formed of a member that is not easily elastically deformed, when the image is transferred from the photosensitive drum 210, the overlapping of the images is not easily displaced. Further, since the intermediate transfer belt 241 and the sheet are in contact with the intermediate transfer roller 246 with a predetermined nip width, when transferring from the intermediate transfer belt 241 to the intermediate transfer roller 246 and when transferring from the intermediate transfer roller 246 to the sheet. It is possible to prevent the transfer accuracy from being lowered. Furthermore, since the paper transport path 27 can be made substantially horizontal, printing can be performed at high speed without being jammed.

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

  (B) In the above embodiment, a wet developer is used. However, the present invention is not limited to this, and an apparatus for forming an image using a dry developer may be used.

  (C) When only a sheet having a high surface smoothness is used, the surface of the intermediate transfer roller 148 or the intermediate transfer roller 246 does not need to have flexibility, and the intermediate transfer belt 141 used in Embodiments 1 and 2 or A material having rigidity equivalent to that of the intermediate transfer belt 241 may be used.

1 is an overall schematic diagram of a color printer according to a first embodiment. FIG. 4 is an overall schematic diagram of a color printer according to a second embodiment.

Explanation of symbols

1, 2 Color printer (image forming device)
14, 24 Transfer section (transfer device)
17, 27 Paper transport unit 110, 210 Photosensitive drum (image carrier)
113, 213 Liquid developing device (developing device)
141, 241 Intermediate transfer belt (intermediate transfer member)
148, 246 Intermediate transfer roller

Claims (2)

A plurality of image carriers capable of carrying images;
A plurality of developing devices capable of supplying a liquid developer to each of the plurality of image carriers;
An intermediate transfer member which is provided in contact with the plurality of image carriers and whose surface is elastically deformable;
An intermediate transfer roller to which an image is transferred from the intermediate transfer member;
A paper transport unit for transporting paper so as to contact the intermediate transfer roller;
With
The plurality of image carriers and the developing device are arranged below the intermediate transfer member and arranged side by side along an oblique direction so that positions in the height direction are gradually different.
The intermediate transfer member is formed to extend in an oblique direction, is an annular belt member having higher rigidity than the intermediate transfer roller, and is stretched between two rollers. The intermediate transfer member A predetermined portion of the plurality of image carriers is rotated in a direction of sequentially contacting the image carrier located on the lower side from the image carrier located on the upper side of the plurality of image carriers,
The intermediate transfer roller is in the sandwiched state of the belt member of the intermediate transfer member between the lower side of the lower side roller of said two rollers, the lower the lower end of the extending direction of the intermediate transfer member From the side ,
The diameter of the intermediate transfer roller is larger than the diameter of the lower roller,
An image forming apparatus , wherein a lower end portion of the intermediate transfer roller is positioned below a lower end portion of the plurality of image carriers and the developing device. The image forming apparatus according to claim 1 , wherein the sheet conveying unit is formed substantially horizontally.

Images