JP4198567B2 - Wet color image forming apparatus - Google Patents

Description

  The present invention relates to a wet color image forming apparatus that obtains a color image by superimposing a plurality of color toner images made of a liquid developer.

A wet image forming apparatus that obtains an image using a liquid developer can achieve a high image quality because it can use very fine toner of submicron size, and it is economical because a sufficient image density can be obtained with a small amount of toner. It can be realized texture of offset printing comparable on top is further possible like that can achieve energy saving and high speed for relatively be low temperature fixing to paper the toner image is compared with dry image forming apparatus using powder toner Are better.

In such a wet image forming apparatus, in order to improve the transferability of the toner image formed on the photoconductor, conventionally, there is an apparatus for sufficiently drying the toner image on the photoconductor by a drying mechanism before the transfer. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 2002-108158 (pages 3, 4 and 1) For example, in (Patent Document 1), after developing with a liquid developer, a drying gas is blown from a spray nozzle to dry a visible image. After that, the toner image is primarily transferred to the intermediate transfer roller and further transferred to the paper to obtain an image.

On the other hand, a color image forming apparatus has been conventionally formed on a plurality of photoconductors so as to reduce the number of liquid developers superimposed on the photoconductor in order to improve light transmission during exposure. There is a device that superimposes a color toner image on a sheet or an intermediate transfer medium. (For example, refer to Patent Document 2).
For example, in Japanese Patent Application Laid-Open No. 2003-66739 (pages 5 and 6, FIG. 1), for example, (Patent Document 2), cyan (C) and black (K) are used for each of two photoconductors in a dry image forming apparatus. Alternatively, at most two colors of magenta (M) and yellow (Y) are overlaid, the two-color image is primarily transferred from the two photoconductors to the belt 20, and then secondarily transferred onto the transfer material P.

  However, in a wet color image forming apparatus that obtains a good transfer image, when a plurality of photoconductors are used as in (Patent Document 2), a liquid developer is placed on the upstream side of the transfer device around each photoconductor. A drying device for drying must be arranged, and a space for the drying is required. In particular, the space around the photoreceptor has been reduced due to the recent demand for miniaturization of wet color image forming apparatuses, while the increase in speed has led to an apparatus requiring a relatively large drying device such as a multistage nozzle block. In this case, the drying device interferes with an image forming unit around the adjacent photoconductor, and there is a possibility that it is difficult to secure a space for arranging the drying device.

  Therefore, the present invention solves the above-described problems, and when obtaining a color image using a liquid developer using a plurality of photoconductors, the degree of freedom of installation of various devices around the photoconductor including the installation position of the drying device is increased. Wet color image that obtains a high-quality color image with good transferability by ensuring sufficient space to arrange the drying device without sacrificing downsizing and ensuring that the toner image is dried An object is to provide a forming apparatus.

The present invention is as a means for solving the above problems, a plurality of image holding member on which an electrostatic latent image on the cylindrical surface is formed which rotates about an axis which is arranged along the conveying path of the transfer medium member A liquid developing device that develops an electrostatic latent image on the surface of the image carrier using a liquid developer, and the surface of the image carrier that is disposed downstream of the liquid developing device in the rotation direction of the image carrier. A plurality of image forming units for forming a developed image on the plurality of image carriers, and the developed image formed on the image carrier is secondarily transferred. A first transfer unit that transfers the image onto the transfer medium; and a second transfer unit that transfers the developed image formed on the image holding member to the transfer medium after tertiary transfer. The image holders are arranged next to each other across a plane of symmetry Is to include first and second image holding member rotating in opposite directions, the liquid developer of the said drying device and said second image holding member surface to dry the liquid developer of the first image holding member surface The drying device that dries the agent is integrally arranged between the respective axes of the first and second image carriers in the direction along the conveyance path and symmetrical with respect to the symmetry plane, The developed image formed on the first image carrier is transferred to the first transfer unit, the developed image formed on the second image carrier is transferred to the second transfer unit, and Using the first transfer unit or the first transfer unit, the developed images formed on the plurality of image holding members are transferred onto the transfer medium.

  According to the present invention, each development image formed on a plurality of image holding members is subjected to secondary transfer or tertiary transfer and multiple transfer onto the same transfer medium, thereby allowing various mechanisms around the photoconductor to be installed freely. The degree of improvement can be improved, and a sufficient installation area for the drying device can be secured around each of the plurality of image carriers. Accordingly, it is possible to cope with the downsizing of the image holders, sufficiently dry the developed images on the respective image holders, and obtain high-quality color images with good transferability.

  In the present invention, in order to improve the degree of freedom of installation of each of the plurality of photoconductors and to ensure a sufficient installation area of the drying device, the toner image on the photoconductor is secondarily or thirdarily transferred to a transfer medium. The toner image is transferred in multiple layers.

  FIG. 1 shows a first embodiment of the present invention. FIG. 1 shows an image forming unit 10 of an electrophotographic apparatus which is a wet color image forming apparatus of the present invention. The image forming unit 10 outputs toner images of yellow (Y), magenta (M), cyan (C), and black (BK) along the sheet conveyance path 11 of the sheet P that is a transfer medium that travels in the direction of the arrow q. The first to fourth photoconductor drums 12 to 15 that are image carriers on which the toner is formed are arranged.

  The first to fourth photosensitive drums 12 to 15 have the same structure, and are formed by forming an organic or amorphous silicon photosensitive layer on a conductive drum made of, for example, aluminum. In the image forming unit 10, the first and third photosensitive drums 12 and 14 rotate in the arrow r direction, and the second and fourth photosensitive drums 13 and 15 rotate in the arrow s direction.

  Around the first or third photosensitive drum 12, 14, a yellow (Y) toner image or a cyan (C) toner image, which is a developed image, is formed along the rotation in the direction of the arrow r. Third image forming units 17 and 19 are provided. The first or third image forming unit 17 or 19 has a different color of liquid toner that is a liquid developer. The first and third image forming units 17 and 19 are selectively charged with the charging devices 22Y and 22C for charging the surfaces of the photosensitive drums 12 and 14 and yellow (Y) or cyan (C). 12 and 14 have exposure devices 23Y and 23C for forming electrostatic latent images on the surfaces.

  The first or third image forming units 17 and 19 are developing rollers that supply yellow (Y) or cyan (C) liquid toners 24Y and 24C to the photosensitive drums 12 and 14 downstream of the exposure devices 23Y and 23C, respectively. 26Y and 26C, developing devices 28Y and 28C having squeeze rollers 27Y and 27C for removing the fog of the developed toner image and removing the solvent, a drying device, and supplying a flow of air to dry the solvent on the toner image It has nozzle blocks 30Y and 30C.

  A yellow (Y) or cyan (C) toner image on the photosensitive drums 12, 14 is downstream of the first or third image forming units 17, 19 of the first or third photosensitive drums 12, 14. First transfer units 31 </ b> Y and 31 </ b> C that perform secondary transfer and form the sheet P are provided. The first transfer units 31Y and 31C have first intermediate transfer rollers 32Y and 32C that are first intermediate transfer media and are driven to rotate in the direction of arrow t at the primary transfer position around the photosensitive drums 12 and 14.

  Further, the first transfer units 31Y and 31C are driven to rotate in the direction of the arrow u at the secondary transfer positions around the first intermediate transfer rollers 32Y and 32C via the paper transport path 11, and the first intermediate transfer rollers 32Y and 32Y 32C, the photosensitive drums 12 and 14, and the first intermediate transfer rollers 32Y and 32C and pressure rollers 33Y and 33C for bringing the paper P into pressure contact with each other. Heaters 41Y and 41C are disposed inside the pressure rollers 33Y and 33C. Photoconductor cleaners 34Y and 34C for collecting residual toner on the photoconductor drums 12 and 14 are provided downstream of the first or third transfer units 31Y and 31C.

  The heater may be disposed inside the intermediate transfer roller instead of inside the pressure roller or in addition to the inside of the pressure roller.

  On the other hand, around the second or fourth photosensitive drums 13 and 15, a magenta (M) toner image or a black (BK) toner image, which is a developed image, is formed along the rotation in the arrow s direction. Alternatively, fourth image forming units 18 and 20 are provided. The second or fourth image forming units 18 and 20 have charging devices 22M and 22BK, and exposure devices 23M and 23BK that selectively perform light irradiation of magenta (M) or black (BK).

  The second or fourth image forming units 18 and 20 have developing rollers 26M and 26BK and squeeze rollers 27M and 27BK downstream of the exposure devices 23M and 23BK, and magenta (M) or black ( BK) developing devices 28M and 28BK for supplying liquid toners 24M and 24BK, respectively, and multistage nozzle blocks 30M and 30BK for supplying an air flow to dry the solvent on the toner image.

  A magenta (M) or black (BK) toner image on the photosensitive drums 13 and 15 is downstream of the second or fourth image forming units 18 and 20 around the second or fourth photosensitive drums 13 and 15. Are transferred, and second transfer units 37M and 37BK are provided.

  The second transfer unit 37M on the second photosensitive drum 13 side is a second intermediate transfer medium, and is a second intermediate that is driven to rotate in the direction of the arrow v at the primary transfer position around the second photosensitive drum 13. The image forming apparatus includes a transfer roller 38M, a first intermediate transfer roller 32C that is a third intermediate transfer medium and is in contact with a secondary transfer position around the second intermediate transfer roller 38M, and a pressure roller 33C. The first intermediate transfer roller 32C serves as both the first intermediate transfer medium of the first transfer unit 31C and the third intermediate transfer medium of the second transfer unit 37M.

  The second transfer unit 37BK on the fourth photoconductor drum 15 side is a second intermediate transfer medium, and is a second intermediate transfer medium that is driven to rotate in the direction of the arrow v at the primary transfer position around the fourth photoconductor drum 15. A roller 38BK, a third intermediate transfer medium, a third intermediate transfer roller 39BK that is driven to rotate in the direction of the arrow w at the secondary transfer position around the second intermediate transfer roller 38BK, and a pressure that rotates in the direction of the arrow u. And a roller 33BK. A heater 41BK is disposed inside the pressure roller 33BK. Photoreceptor cleaners 34M and 34BK for collecting residual toner on the photoreceptor drums 12 and 14 are provided downstream of the second or fourth transfer units 31M and 31BK. Reference numeral 40 denotes an intermediate transfer cleaner.

  First and third image forming units 17 and 19 around the first and third photosensitive drums 12 and 14 and second and fourth image formation around the second and fourth photosensitive drums 13 and 15. The units 18 and 20 are arranged so as to be line symmetric. The multi-stage nozzle blocks 30Y and 30M are integrally arranged in a space between the first and second photosensitive drums 12 and 13. The multi-stage nozzle blocks 30C and 30BK are integrally arranged in a space between the third and fourth photosensitive drums 14 and 15. Therefore, the space occupied by the multi-stage nozzle blocks 30Y, 30M, 30C, and 30BK in the image forming unit 10 is reduced in size compared to the case where they are arranged apart.

  Next, the operation will be described. When the image forming process is started, the first to fourth photosensitive drums 12 to 15 rotate in the direction of the arrow r or the arrow s, respectively, and the toner image forming operation is performed by the image forming units 17 to 20. The For example, in the first photosensitive drum 12, after the first photosensitive drum 12 is uniformly charged by the charging device 22Y, yellow (Y) exposure corresponding to the image information is selectively performed by the exposure device 23Y. To form a yellow (Y) electrostatic latent image on the first photosensitive drum 12.

  Next, the yellow (Y) liquid toner 24Y is supplied from the developing roller 26Y to the first photosensitive drum 12 from the developing roller 26Y by the developing device 28Y, the fog is removed and the solvent is removed by the squeeze roller 27Y, and the yellow (Y) toner image is displayed. It is formed. Thereafter, the yellow (Y) toner image is dried by the airflow from the multi-stage nozzle block 30Y and reaches the first intermediate transfer roller 32Y.

  Similarly, magenta (M), cyan (C), and black (BK) toner images are formed on the second to fourth photosensitive drums 13 to 15 and reach the transfer position. The second photosensitive drum 13 reaches the second intermediate transfer roller 38M after the magenta (M) toner image is formed. The third photosensitive drum 14 reaches the first intermediate transfer roller 32C after the cyan (C) toner image is formed. The fourth photosensitive drum 15 reaches the second intermediate transfer roller 38BK after the black (BK) toner image is formed.

  The paper P is supplied to the paper transport path 11 in synchronization with the toner image formation timing on each of the photoconductive drums 12 to 15, and the paper P is sequentially turned yellow ( Y), magenta (M), cyan (C), and black (BK) toner images are multiple-transferred. That is, the yellow (Y) toner image on the first photosensitive drum 12 is primarily transferred to the first intermediate transfer roller 32Y and then secondarily transferred to the paper P.

  On the other hand, the magenta (M) toner image on the second photosensitive drum 13 and the cyan (C) toner image on the third photosensitive drum 14 are color-superposed on the first intermediate transfer roller 32C. After that, multiple transfer is performed on the paper P on which the yellow (Y) toner image is formed. That is, the cyan (C) toner image on the third photosensitive drum 14 is primarily transferred to the first intermediate transfer roller 32C. Further, the magenta (M) toner image on the second photosensitive drum 13 is primarily transferred to the second intermediate transfer roller 38M and then secondarily transferred to the first intermediate transfer roller 32C. Therefore, while the cyan (C) toner image is transferred to the paper P by the secondary transfer, the magenta (M) toner image is transferred to the paper P by the tertiary transfer.

  The black (BK) toner image on the fourth photosensitive drum 15 is primarily transferred to the second intermediate transfer roller 38BK and then secondarily transferred to the third intermediate transfer roller 39BK. (Y), magenta (M), cyan (C) toner images are formed on the paper P on which the toner images are formed by multiple transfer, and transferred onto the paper P with yellow (Y), magenta (M), cyan (C), A black (BK) full-color toner image is formed. After the primary transfer is completed, residual toner is removed from the first to fourth photoconductive drums 12 to 15 by the photoconductor cleaners 34Y, 34M, 34C, and 34BK. Further, after the completion of the secondary transfer or the tertiary transfer, the intermediate transfer rollers 32Y, 32C, 38M, 38BK, 39BK are cleaned by the intermediate transfer cleaner 40.

  As described above in detail, according to the present embodiment, the toner on the first and third photosensitive drums 12 and 14 depends on the arrangement of the image forming units 17 to 20 around the photosensitive drums 12 to 15. The image is secondarily transferred and formed on the paper P, while the toner images on the second and fourth photosensitive drums 13 and 15 are thirdarily transferred and formed on the paper P. Therefore, the degree of freedom when installing the image forming units 17 to 20 in the image forming unit 10 can be improved. As a result, the space for installing the multistage nozzle blocks 30Y, 30M, 30C, and 30BK can be reduced, and the multistage nozzle blocks 30Y, 30M, 30C, and 30BK can be installed even when the entire image forming unit 10 is downsized. Sufficient space can be secured, the toner image can be dried well, and a high-quality color image with good transferability can be obtained.

  Further, according to the present embodiment, the image forming units 17 to 20 are installed symmetrically, so that the design of each part of the image forming units 17 to 20 can be made common, and the productivity can be improved and the manufacturing cost can be reduced. Further, the number of parts can be reduced by using the first transfer unit 31C and the second transfer unit 37M as the first intermediate transfer roller 32C.

  FIG. 2 shows a second embodiment of the present invention. In this embodiment, the arrangement of the image forming units in the first embodiment is changed. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the image forming unit 50 of the electrophotographic apparatus shown in FIG. 2, the first and third photosensitive drums 12 and 14 rotate in the direction of the arrow s, and the second and fourth photosensitive drums 13 and 15 indicate the arrows. Rotate in r direction.

  Around the first or third photosensitive drums 12 and 14, charging devices 22Y and 22C and exposure devices 23Y and 23C constituting the first or third image forming units 17 and 19 along the rotation in the direction of the arrow s. Developing devices 28Y and 28C and multi-stage nozzle blocks 30Y and 30C are arranged.

  Toner images on the first or third photosensitive drums 12 and 14 are transferred to the downstream of the first or third image forming units 17 and 19 of the first or third photosensitive drums 12 and 14 by tertiary transfer. Second transfer units 51Y and 51C formed on the paper P are provided. The second transfer units 51Y and 51C are second intermediate transfer rollers which are second intermediate transfer media and are driven to rotate in the direction of arrow v at the primary transfer position around the first or third photosensitive drums 12 and 14. 52Y, 52C, third intermediate transfer rollers 53Y, 53C which are third intermediate transfer media and are driven to rotate in the direction of arrow t at the secondary transfer positions around the second intermediate transfer rollers 52Y, 52C, and pressure rollers 54Y, 54C. Heaters 56Y and 56C are arranged inside the third intermediate transfer rollers 53Y and 53C.

  On the other hand, around the second or fourth photosensitive drums 13 and 15, the charging devices 22M and 22BK and the exposure device 23M constituting the second or fourth image forming units 18 and 20 along the rotation in the direction of the arrow r. , 23BK, developing devices 28M, 28BK, and multistage nozzle blocks 30M, 30BK are arranged.

  Toner images on the second or fourth photosensitive drums 13 and 15 are transferred by secondary transfer downstream of the second or fourth image forming units 18 and 20 of the second or fourth photosensitive drums 13 and 15. First transfer units 57M and 57BK formed on the paper P are provided. The first transfer units 57M and 57BK are first intermediate transfer media and are third intermediate transfer rollers that are driven to rotate in the direction of the arrow t at the primary transfer positions around the second or fourth photosensitive drums 13 and 15. 53Y, 53C and pressure rollers 54Y, 54C. The third intermediate transfer rollers 53Y and 53C serve as both the first intermediate transfer medium of the first transfer units 57M and 57BK and the third intermediate transfer medium of the second transfer units 51Y and 51C.

  First and third image forming units 17 and 19 around the first and third photosensitive drums 12 and 14 and second and fourth image formation around the second and fourth photosensitive drums 13 and 15. The units 18 and 20 are arranged so as to be line symmetric. The multistage nozzle blocks 30Y and 30BK are arranged in empty spaces around the first or fourth photosensitive drums 12 and 15 on both sides of the image forming unit 50, respectively. The multistage nozzle blocks 30M and 30C are arranged in the second and third stages. They are arranged together in a space between the photosensitive drums 13 and 14. Accordingly, the multi-stage nozzle blocks 30Y, 30M, 30C, and 30BK are arranged in the image forming unit 10 by using spaces effectively.

  When the image forming process is started, the first to fourth photosensitive drums 12 to 15 rotate in the direction of the arrow r or the arrow s, respectively, and the toner image forming operation is performed by the image forming units 17 to 20. The After the yellow (Y), magenta (M), cyan (C), and black (BK) toner images are formed on the first to fourth photoconductive drums 12 to 15 and dried, the yellow (Y) toner is used. The image is transferred to the second transfer unit 51Y, the magenta (M) toner image to the first transfer unit 57M, the cyan (C) toner image to the second transfer unit 51C, and the black (BK) toner image to Each reaches the first transfer unit 57BK.

  The yellow (Y) toner image on the first photosensitive drum 12 and the magenta (M) toner image on the second photosensitive drum 13 are color-superposed on the third intermediate transfer roller 53Y. The cyan (C) toner image on the third photoconductor drum 14 and the black (BK) toner image on the fourth photoconductor drum 15 are collectively transferred to the paper P, and the third intermediate transfer roller 53C. After the colors are superimposed on each other, they are transferred onto the paper P at a time.

  That is, in the first transfer units 57M and 57BK, the magenta (M) and black (BK) toner images on the second or fourth photosensitive drums 13 and 15 are transferred to the third intermediate transfer roller 53Y, Primary transferred to 53C. On the other hand, in the second transfer units 51Y and 51C, the yellow (Y) and cyan (C) toner images on the first or third photosensitive drums 12 and 14 are transferred to the second intermediate transfer rollers 52Y and 52Y, respectively. After the primary transfer to 52C, the toner image is secondarily transferred to the third intermediate transfer rollers 53Y and 53C, and the yellow (Y) and magenta (M) toner images or the third intermediate transfer rollers 53Y and 53C, respectively. Cyan (C) and black (BK) toner images are superimposed.

  Thereafter, yellow (Y) and magenta (M) toner images are sequentially transferred from the third intermediate transfer roller 53Y to the sheet P while being conveyed in the direction of the arrow q in the sheet conveyance path 11, and the third intermediate is transferred. Cyan (C) and black (BK) toner images are collectively transferred from the transfer roller 53C to form a full-color toner image.

  As described above in detail, according to this embodiment, the toner images on the first and second photosensitive drums 12 and 14 are transferred according to the arrangement of the image forming units 17 to 20 around the photosensitive drums 12 to 15. The toner images on the second and fourth photosensitive drums 13 and 15 are secondarily transferred and formed on the paper P while being thirdarily transferred and formed on the paper P. Therefore, as in the first embodiment, the degree of freedom when installing the image forming units 17 to 20 in the image forming unit 10 can be improved. Accordingly, a sufficient space for installing the multi-stage nozzle blocks 30Y, 30M, 30C, and 30BK can be ensured regardless of downsizing of the entire image forming unit 10, and a high-quality color image with good transferability can be obtained.

  Further, according to the present embodiment, the image forming units 17 to 20 are arranged symmetrically in the same manner as in the first embodiment, thereby improving the productivity and reducing the manufacturing cost by sharing the design of each part of the image forming units 17 to 20. Can be planned. Further, the first transfer units 57M and 57BK and the second transfer units 51Y and 51C can also be used as the third intermediate transfer rollers 53Y and 53C, thereby reducing the number of parts.

  FIG. 3 shows a third embodiment of the present invention. In this embodiment, toner images are formed in two colors on a single photosensitive drum in the first embodiment. The same portions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 3 shows an image forming unit 60 of an electrophotographic apparatus which is a wet color image forming apparatus of the present invention. In the image forming unit 60, fifth and sixth photosensitive drums 62 and 63 are arranged along a paper conveyance path 61 of the paper P traveling in the direction of the arrow d. In the image forming unit 60, the fifth photosensitive drum 62 rotates in the direction of arrow e, and the sixth photosensitive drum 63 rotates in the direction of arrow f.

  A fifth image forming unit 64 for forming yellow (Y) and cyan (C) toner images along the rotation in the direction of the arrow e is provided around the fifth photosensitive drum 62. Around the drum 63, a sixth image forming unit 65 is provided that forms magenta (M) and black (BK) toner images along the rotation in the direction of the arrow f.

  The fifth image forming unit 64 includes a charging device 22Y, an exposure device 23Y, a developing device 28Y for forming a yellow (Y) toner image, a charging device 22C for forming a cyan (C) toner image, and an exposure device. 23C and developing device 28C. Further, the fifth image forming unit 64 includes a fifth multi-stage nozzle block 67 that dries toner images of two colors of yellow (Y) and cyan (C) before transfer.

  The sixth image forming unit 65 includes a charging device 22M for forming a magenta (M) toner image, an exposure device 23M, a developing device 28M, a charging device 22BK for forming a black (BK) toner image, and an exposure device. 23BK and developing device 28BK. Further, the sixth image forming unit 65 has a sixth multi-stage nozzle block 68 that dries the two-color toner images of magenta (M) and black (BK) before transfer.

  On the downstream side of the fifth image forming unit 64 of the fifth photosensitive drum 62, the yellow (Y) and cyan (C) toner images on the fifth photosensitive drum 62 are collectively transferred to a third sheet. A second transfer unit 70 formed on P is provided. The second transfer unit 70 is a second intermediate transfer medium, which is a fifth intermediate transfer roller 71 that is driven to rotate in the direction of arrow g at the primary transfer position around the fifth photosensitive drum 62, and a third intermediate transfer roller. It has a sixth intermediate transfer roller 72 that is a transfer medium and is driven to rotate in the direction of arrow h at the secondary transfer position around the fifth intermediate transfer roller 71, and a pressure roller 73 that rotates in the direction of arrow j. A heater 74 is disposed inside the sixth intermediate transfer roller 72. Reference numeral 78 denotes a photoreceptor cleaner.

  On the downstream side of the sixth image forming unit 65 of the sixth photosensitive drum 63, the magenta (M) and black (BK) toner images on the sixth photosensitive drum 63 are secondarily transferred collectively to a sheet. A first transfer unit 76 formed on P is provided. The first transfer unit 76 is a first intermediate transfer medium, which is a sixth intermediate transfer roller 72 and a pressure roller 73 that are driven to rotate in the direction of arrow h at the primary transfer position around the sixth photosensitive drum 63. Have The sixth intermediate transfer roller 72 serves as both the first intermediate transfer medium of the first transfer unit 76 and the third intermediate transfer medium of the second transfer unit 70.

  The fifth image forming unit 64 around the fifth photosensitive drum 62 and the sixth image forming unit 65 around the sixth photosensitive drum 63 are arranged to be line-symmetric. The fifth and sixth multi-stage nozzle blocks 67 and 68 are arranged in empty spaces around the fifth or sixth photosensitive drums 62 and 63 on both sides of the image forming unit 60. Therefore, the multi-stage nozzle blocks 67 and 68 are arranged in the image forming unit 60 by using the space effectively.

  When the image forming process is started, the fifth photosensitive drum 62 rotates in the direction of arrow e, and the sixth photosensitive drum 63 rotates in the direction of arrow f, so that a toner image forming operation is performed. In the fifth photoconductor drum 62, after the fifth photoconductor drum 62 is charged by the charging device 22Y, the exposure device 23Y selectively irradiates yellow (Y) exposures to obtain the yellow (Y) exposure. An electrostatic latent image is formed, and a yellow (Y) toner image is formed by the developing device 28Y.

  Next, after charging the fifth photosensitive drum 62 by the charging device 22C, the exposure device 23C selectively irradiates cyan (C) exposure to form a cyan (C) electrostatic latent image, and the developing device. A cyan (C) toner image is formed on the yellow (Y) toner image by 28C. Thereafter, the yellow (Y) and cyan (C) toner images on the fifth photosensitive drum 62 are dried by the fifth multistage nozzle block 67 and then reach the second transfer unit 70.

  In the sixth photosensitive drum 63, after the sixth photosensitive drum 63 is charged by the charging device 22M, the exposure device 23M selectively irradiates the magenta (M) exposure to the magenta (M). An electrostatic latent image is formed, and a magenta (M) toner image is formed by the developing device 28M.

  Next, after charging the sixth photosensitive drum 63 by the charging device 22BK, the exposure device 23BK selectively irradiates black (BK) exposure to form a black (BK) electrostatic latent image, and the developing device A black (BK) toner image is formed on the magenta (M) toner image by 28BK. Thereafter, the magenta (M) and black (BK) toner images on the sixth photosensitive drum 63 are dried by the sixth multi-stage nozzle block 68 and then reach the first transfer unit 76.

  The yellow (Y) and cyan (C) toner images on the fifth photosensitive drum 62 and the magenta (M) and black (BK) toner images on the sixth photosensitive drum 63 are the sixth intermediate. After the color is superimposed on the transfer roller 72, it is transferred onto the paper P at a time. That is, the yellow (Y) and cyan (C) toner images on the fifth photosensitive drum 62 that have reached the second transfer unit 70 are primarily transferred to the fifth intermediate transfer roller 71 and then transferred to the fifth intermediate transfer roller 71. Secondary transfer is performed to the intermediate transfer roller 72 of No. 6. The magenta (M) and black (BK) toner images on the sixth photoconductive drum 63 that have reached the first transfer unit 76 are primarily transferred to the sixth intermediate transfer roller 72, and the sixth A yellow (Y), magenta (M), cyan (C), and black (BK) full-color toner image is formed on the intermediate transfer roller 72.

  Thereafter, the sheet P is transferred and formed with a full-color toner image of yellow (Y), magenta (M), cyan (C), and black (BK) while passing between the sixth intermediate transfer roller 72 and the pressure roller 73. Is done.

  As described above in detail, according to this embodiment, the toner image on the fifth photosensitive drum 62 is thirdarily transferred in accordance with the arrangement of the image forming units 64 and 65 around the photosensitive drums 62 and 63. While the toner image is formed on the paper P, the toner image on the sixth photosensitive drum 63 is secondarily transferred and formed on the paper P. Accordingly, the degree of freedom in installing the image forming units 64 and 65 can be improved, and the multi-stage nozzle blocks 67 and 68 are secured with sufficient margins on both sides of the image forming unit 60 regardless of the downsizing of the entire image forming unit 60. The space for the multi-stage nozzle blocks 67 and 68 can be secured sufficiently, and a high-quality color image with good transferability can be obtained.

  Further, according to this embodiment, since two color toner images are superimposed on the respective photosensitive drums 62 and 63, compared to a case where a full color toner image is superimposed on a single photosensitive drum, the exposure time is larger. It is almost unaffected by reduced light transmission, and after forming a single color toner image on a single photoconductive drum, it can be used to correct misalignment during transfer compared to full color transfer. Can be easily performed.

  Further, according to the present embodiment, the fifth and sixth image forming units 64 and 65 are arranged symmetrically in the same manner as in the first embodiment, so that the design of each part of the image forming units 64 and 65 can be made common, and production can be performed. The improvement of productivity and the reduction of manufacturing cost can be achieved. Further, the number of parts can be reduced by using the first transfer unit 76 and the second transfer unit 70 as the sixth intermediate transfer roller 72.

  FIG. 4 shows a fourth embodiment of the present invention. In this embodiment, the first transfer unit and the second transfer unit are configured differently in Embodiment 3, and five types of liquid toner are used. The same parts as those in Embodiment 3 are the same. Reference numerals are assigned and description thereof is omitted. Around the fifth photosensitive drum 62 of the image forming unit 80 shown in FIG. 4, toner images of three colors of special colors (S), yellow (Y), and cyan (C) are rotated along the direction of the arrow e. A seventh image forming unit 81 to be formed is provided, and a sixth magenta (M) and black (BK) toner image is formed around the sixth photosensitive drum 63 along the rotation in the direction of the arrow f. An image forming unit 65 is provided.

  The seventh image forming unit 81 includes a charging device 22S for forming a special color (S) toner image, an exposure device 23S, a developing device 28S, a charging device 22Y for forming a yellow (Y) toner image, and an exposure. The image forming apparatus includes a device 23Y, a developing device 28Y, a charging device 22C for forming a cyan (C) toner image, an exposure device 23C, and a developing device 28C. Further, the seventh image forming unit 81 has a fifth multi-stage nozzle block 67 for drying the toner images of three colors of special colors (S), yellow (Y) and cyan (C) before transfer.

  The special color (S), yellow (Y), and cyan (C) toner images on the fifth photosensitive drum 62 are batched downstream of the seventh image forming unit 81 around the fifth photosensitive drum 62. Then, a second transfer unit 82 for performing third transfer and forming on the paper P is provided. The second transfer unit 82 is a second intermediate transfer medium, which is a seventh intermediate transfer roller 83 that is driven to rotate in the direction of arrow k at the primary transfer position around the fifth photosensitive drum 62, and a third intermediate transfer roller 83. It has an eighth intermediate transfer roller 84 that is a transfer medium and is driven to rotate in the direction of arrow l at the secondary transfer position around the seventh intermediate transfer roller 83, and a pressure roller 86 that rotates in the direction of arrow m.

  On the downstream side of the sixth image forming unit 65 of the sixth photosensitive drum 63, the magenta (M) and black (BK) toner images on the sixth photosensitive drum 63 are secondarily transferred collectively to a sheet. A first transfer unit 87 formed on P is provided. The first transfer unit 87 is a first intermediate transfer medium, which is a ninth intermediate transfer roller 88 that is driven to rotate in the direction of arrow n at the primary transfer position around the sixth photosensitive drum 63, and in the direction of arrow m. And a pressure roller 90 that rotates. A heater 91 is disposed inside the pressure rollers 86 and 90.

  The fifth multi-stage nozzle block 67 around the fifth photoconductor drum 62 and the sixth multi-stage nozzle block 68 around the sixth photoconductor drum 63 are arranged so as to be line symmetric, and the image forming unit 80. It is arranged using the space on both sides effectively.

  When the image forming process is started, the fifth photosensitive drum 62 forms a toner image of three colors of special color (S), yellow (Y) and cyan (C), After being dried by the multistage nozzle block 67, it reaches the second transfer unit 82. The three color toner images on the fifth photosensitive drum 62 are primarily transferred to the seventh intermediate transfer roller 83 and secondarily transferred to the eighth intermediate transfer roller 84, and then collectively onto the paper P. Tertiary transfer is performed.

  In the sixth photosensitive drum 63, after forming two-color toner images of magenta (M) and black (BK), the toner image is dried by the sixth multistage nozzle block 68, and then the first transfer unit 87. To reach. The two color toner images on the sixth photosensitive drum 63 are primarily transferred to the ninth intermediate transfer roller 88, and then the special color (S), yellow (Y) and cyan (C) on the paper P. ) Are collectively transferred onto the three color toner images, and a full color toner image including the special color (S) is formed on the paper P.

  As described above in detail, according to the present embodiment, as in the third embodiment, the degree of freedom in installing the sixth or seventh image forming units 65 and 81 can be improved. It can be installed in a space secured on both sides of the image forming unit 80, can obtain a sufficient drying effect, and can obtain a high-quality color image with good transferability.

  Further, according to this embodiment, since the toner images are superimposed on the respective photosensitive drums 62 and 63 in three colors and two colors, the full-color toner images are superimposed on a single photosensitive drum. Compared to the case where there is almost no influence of light transmittance being reduced at the time of exposure, and compared to the case where one color toner image is formed on one photosensitive drum and then full color is superimposed by transfer. Misalignment correction at the time of transfer can be easily performed.

  Further, according to this embodiment, the fifth and sixth multi-stage nozzle blocks 67 and 68 are arranged symmetrically, so that the design of each part of the multi-stage nozzle blocks 67 and 68 can be made common, thereby improving productivity and manufacturing. Cost can be reduced. Further, the first transfer unit 87 and the second transfer unit 82 are configured separately, and by superimposing images on the paper P, each photosensitive drum is compared with the case of superimposing images on an intermediate transfer medium. The image formation timing can be adjusted independently for each of 62 and 63, and the image formation timing can be easily adjusted.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention, and the structure of the image forming apparatus is arbitrary. For example, the number of liquid developers to be used, the type of color, etc. It is not limited. Further, in order to improve the drying property of the toner image by the drying device, a removal device for absorbing and removing the solvent on the toner image may be provided before reaching the drying device. Further, the structure of the first or second transfer unit is not limited, and it is not necessary to provide a heater or the like inside the intermediate transfer medium or the pressure roller, and an endless belt can also be used as the intermediate transfer medium.

1 is a configuration diagram schematically illustrating an image forming unit according to a first exemplary embodiment of the present invention. It is a block diagram which shows roughly the image formation part of Example 2 of this invention. It is a block diagram which shows roughly the image formation part of Example 3 of this invention. It is a block diagram which shows roughly the image formation part of Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image formation part 11 ... Paper conveyance path 12-15 ... 1st-4th photoconductor drums 17-20 ... 1st-4th image formation unit 22Y, 22M, 22C, 22BK ... Charging device 23Y, 23M, 23C, 23BK ... exposure devices 28Y, 28M, 28C, 28BK ... developing devices 30Y, 30M, 30C, 30BK ... drying devices 31Y, 31C ... first transfer units 32Y, 32C ... first intermediate transfer roller 33 ... pressure roller 37M, 37BK, second transfer unit 38M, 38BK, second intermediate transfer roller 39BK, third intermediate transfer roller

Claims (6)

A plurality of image holding member on which an electrostatic latent image is formed on the cylindrical surface which rotates about an axis which is arranged along the conveying path of the transfer medium body,
A liquid developing device that develops an electrostatic latent image on the surface of the image carrier using a liquid developer, and a liquid on the surface of the image carrier that is disposed downstream of the liquid developing device in the rotation direction of the image carrier. A plurality of image forming units that have a drying device for drying the developer and that form a developed image on the plurality of image carriers;
A first transfer unit that secondarily transfers the developed image formed on the image holding member and transfers the developed image onto the transfer medium;
A second transfer unit that thirdarily transfers the developed image formed on the image holding member and transfers the developed image onto the transfer medium;
The image carrier includes first and second image carriers that are arranged adjacent to each other across a plane of symmetry and rotate in opposite directions, and dry the liquid developer on the surface of the first image carrier. The drying device and the drying device for drying the liquid developer on the surface of the second image carrier are symmetrical to each other with respect to the symmetry plane, and are arranged in the direction along the conveyance path of the first and second image carriers. The developed image formed on the first image holding member is integrally arranged between the respective shafts, and is transferred to the first transfer unit to be formed on the second image holding member. The developed image is transferred to the second transfer unit, and the developed images formed on the plurality of image carriers are multiplexed on the transfer medium using the first transfer unit or the second transfer unit. Characterized by transcription That wet color image forming apparatus. The first transfer unit has a cylindrical first intermediate transfer medium interposed between the image carrier and the transfer medium;
The second transfer unit includes a cylindrical second intermediate transfer medium and a cylindrical third intermediate transfer medium interposed between the image carrier and the transfer medium. Item 2. The wet color image forming apparatus according to Item 1. The third image holding body is disposed on the opposite side of the first image holding body with respect to the second image holding body and rotates in the direction opposite to the rotation direction of the second image holding body. And the developed image formed on the third image carrier is secondarily transferred to the medium to be transferred via the third intermediate transfer medium onto which the developed image on the second image carrier is transferred. wet color image forming apparatus according to claim 2, characterized in that it is transcribed. The third image holding body is disposed on the opposite side of the second image holding body with respect to the first image holding body and rotates in the direction opposite to the rotation direction of the first image holding body. And the developed image formed on the third image holding member is tertiary to the transfer medium via the first intermediate transfer medium onto which the developed image on the first image holding member is transferred. wet color image forming apparatus according to claim 2, characterized in that it is transcribed. 2. The plurality of adjacent image holding members are rotated in opposite directions, and the plurality of image forming units are arranged substantially line-symmetrically for each of the plurality of adjacent image holding members. The wet color image forming apparatus according to claim 3 . 5. The image forming unit according to claim 1, wherein at least one of the plurality of image forming units includes a plurality of the liquid developing devices, and forms a plurality of color developed images on the image holding member. The wet color image forming apparatus according to any one of the above .

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