JP2005315945A - Development device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a development device, capable of stably developing an electrostatic latent image to a visible image by uniformly forming the thin layer of liquid developer with transport rollers and a developing roller, without causing layer unevenness in the axial direction of the rollers. <P>SOLUTION: The electrostatic latent image on a photoreceptor drum 25 is visualized by supplying the liquid developer stored at the lower part in a liquid developer storage container to the developing roller 37, through a plurality of transport rollers 38 and 39. At least one transport roller 38 from among a plurality of transport rollers 38 and 39 is reciprocated in its axial direction, at prescribed strokes while it is being rotated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing device in a wet image forming apparatus employed in a copying machine, a facsimile machine, a printer, or the like.

  In general, in this type of image forming apparatus, an electrostatic latent image is formed by irradiating the surface of a photosensitive drum with light according to image information, and toner and carrier are formed on the electrostatic latent image. A liquid developer made of a liquid is attached by a developing roller of a developing device, whereby a toner image is formed on the photosensitive drum. Further, the liquid developer stored in the liquid developer storage container of the developing device is stirred and mixed by a stirring screw, and supplied and applied to the outer peripheral surface of the developing roller by a conveying roller including a supply roller and an application roller. It has become so.

By the way, in the developing device having such a configuration, a uniform thin layer of liquid developer is formed by a plurality of conveying rollers and developing rollers in order to stably visualize the electrostatic latent image on the photosensitive drum. Thus, it is necessary to supply the photosensitive drum onto the photosensitive drum. Therefore, for example, as a conventional developing device, as disclosed in Patent Document 1, a plurality of application rollers are brought into contact with the developing roller in a daisy chain state, or two pairs of developing rollers and a conveying roller are opposed to the photosensitive drum. Arrangements to be arranged have been proposed.
JP-A-8-328392

  However, even in these conventional developing devices, a plurality of streaky lines extending in the circumferential direction of the roller with the rotational contact portion between the rollers as a base point in the thin layer of the liquid developer formed by the conveying roller and the developing roller. There was a problem that layer unevenness occurred and it was difficult to form a uniform thin layer. Further, when an anilox roller having a large number of block-like patterns on the outer peripheral surface is used as a roller in the plurality of transport rollers, the anilox roller pattern appears in the image or bubbles are generated. There was a problem.

  The present invention has been made paying attention to such problems existing in the prior art. Its purpose is to form a thin layer of liquid developer evenly in the circumferential direction of the roller with the transport roller and the developing roller without causing unevenness of the layer, and to stably visualize the electrostatic latent image. It is an object of the present invention to provide a developing device that can do this.

  Another object of the present invention is that when an anilox roller is used as an arbitrary roller among a plurality of transport rollers, the pattern of the anilox roller may appear in an image or air bubbles may be generated. An object of the present invention is to provide a developing device that can be suppressed.

  In order to achieve the above object, according to the first aspect of the present invention, the liquid developer stored in the lower part of the case is supplied to the developing roller through a plurality of conveying rollers to visualize the electrostatic latent image. The developing device is characterized in that an operating means for reciprocating at least one transport roller with a predetermined stroke along the axial direction thereof is provided.

  Here, the transport roller is not limited to a roller mainly intended for transport of the liquid developer, but may be a roller positioned in the transport path of the liquid developer. For example, the charge roller according to the third embodiment described later. Even a roller is a conveyance roller.

  The invention according to claim 2 is the invention according to claim 1, wherein the reciprocating transport roller is shorter than the downstream roller in contact with the transport roller and between both ends of the downstream roller. It is characterized by being reciprocated at the position of

  According to a third aspect of the present invention, in the invention according to the first or second aspect, the reciprocating transport roller is made of a material different in outer peripheral surface from the outer peripheral surface of another roller in contact therewith. It is characterized by this.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, a charging roller is disposed so as to come into contact with the developing roller, and the transport roller is reciprocated. Instead, the charging roller is reciprocated with a predetermined stroke in the axial direction by the operating means.

  According to the invention described in claim 1, when the thin layer of the liquid developer is formed by the plurality of transport rollers and the developing roller, the at least one transport roller is reciprocated in the axial direction. It is possible to suppress the occurrence of layer unevenness in the circumferential direction of the roller in the thin layer. Therefore, a thin layer of the liquid developer can be formed uniformly, and the electrostatic latent image can be stably visualized. In addition, since at least one transport roller is reciprocated in the axial direction, when an anilox roller is used as a roller in a plurality of transport rollers, the anilox roller pattern appears in the image or bubbles are generated. Or the risk of losing.

  According to the second aspect of the present invention, the excessive supply layer of the liquid developer formed at the end portion of the upstream conveying roller can be extended by the reciprocating motion of the conveying roller in the axial direction. It is possible to prevent the supply layer from being supplied to the conveyance roller on the downstream side and causing a problem such as liquid leakage.

  According to the third aspect of the present invention, the at least one transport roller is reciprocated in the axial direction in contact with a roller made of a different material, so that the thin layer of liquid developer is moved in the axial direction of the roller. It is possible to more effectively suppress the occurrence of layer unevenness.

  According to the fourth aspect of the present invention, a thin layer of the liquid developer can be uniformly formed without causing unevenness in the axial direction of the roller by reciprocating the charging roller in the axial direction.

(First embodiment)
Hereinafter, an embodiment in which the present invention is embodied in a tandem color image forming apparatus (hereinafter simply referred to as a wet image forming apparatus) will be described with reference to the drawings.

  As shown in FIG. 1, the wet image forming apparatus includes a paper feed mechanism 11, a vertical conveyance path 12, a registration roller pair 13, a belt conveyance mechanism 14, a first image formation mechanism 15, a second image formation mechanism 16, and a first image formation mechanism 16. 3 image forming mechanism 17, fourth image forming mechanism 18, secondary transfer mechanism 19, fixing mechanism 20, discharge conveyance path 21, discharge tray 22, intermediate transfer cleaning unit 23, and the like. The paper feed mechanism 11 includes a paper feed cassette 11a and a pickup roller 11b, and transports the paper P in the paper feed cassette 11a to the vertical transport path 12 by the pickup roller 11b. The vertical conveyance path 12 conveys the paper P conveyed from the paper feeding mechanism 11 to the secondary transfer mechanism 19 via the registration roller pair 13.

  The belt conveying mechanism 14 includes a driving roller 14a, a driven roller 14b, and an endless intermediate transfer belt 14c that is stretched between the rollers 14a and 14b. The intermediate transfer belt 14c is maintained in an appropriate tension state by a tension roller 14d. Then, the drive roller 14a is rotated by a drive motor (not shown), so that the intermediate transfer belt 14c has a peripheral speed equivalent to the peripheral speed of the photosensitive drum 25 of each of the image forming mechanisms 15 to 18 described later, as shown in FIG. It is driven in the direction of the arrow.

  The first to fourth image forming mechanisms 15 to 18 are arranged for black (BK), magenta (M), cyan (C), and yellow (Y) from the left side in FIG. It has become. Here, for convenience of explanation, the configuration of the first image forming mechanism 15 will be described in detail with the first image forming mechanism 15 as a representative of image formation. Note that, in the other image forming mechanisms 16 to 18, the same components as those of the first image forming mechanism 15 are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 2, the first image forming mechanism 15 includes a photosensitive drum 25 as an image carrier, a main charging device 26, an LPH (LED PRINT HEAD) 27, and a liquid developer as a developing device constituting a developing unit. The apparatus 28, a primary transfer mechanism 29, a cleaning mechanism 30, and a static elimination lamp 31 are configured. These portions 25 to 31 are assembled in a synthetic resin casing so as to constitute one unit, and are attached to a body frame (not shown) of the wet image forming apparatus.

  The photosensitive drum 25 is made of an amorphous silicon drum, and is charged by the main charging device 26 so that the dark potential at the developing position is about 300V. Then, the surface of the charged photosensitive drum 25 is irradiated with light according to image information from the LPH 27, whereby an electrostatic latent image is formed on the surface of the photosensitive drum 25.

  The liquid developing device 28 uses a liquid developer composed of toner and carrier liquid with stirring and mixing so as to have a predetermined concentration, and the liquid developer is irradiated with light on the photosensitive drum 25 by a developing roller. A toner image is formed (developed) on the photosensitive drum 25 by applying to the electrostatic latent image of the portion. For this purpose, the dark potential of the photosensitive drum 25 is set to 300V, the developing bias is 200V, and the post-exposure potential is 20V. That is, the dark potential corresponds to the white portion of the image and the post-exposure potential corresponds to the black portion of the image, and this difference is a so-called contrast potential.

  The toner image developed (developed) from the electrostatic latent image on the photosensitive drum 25 as described above is transferred to the intermediate transfer belt 14c of the belt transport mechanism 14 by the nip with the primary transfer mechanism 29. . The primary transfer mechanism 29 includes a transfer roller, and a voltage having a polarity opposite to the surface potential of the photosensitive drum 25 is applied at a predetermined set value within a range of −200 to −1300V. The potential for image formation is set to an optimal value according to the characteristics of the photosensitive drum 25, the performance of the liquid developer 35, the environment, and the like.

  On the other hand, the transfer residual liquid developer remaining without being transferred on the photosensitive drum 25 is scraped off by a cleaning blade 47 described later in the cleaning mechanism 30 of the next process. Further, the photosensitive drum 25 is neutralized by a neutralizing lamp 31 so as to make the residual potential on the surface uniform and is prepared for the next series of image forming steps. In this wet image forming apparatus, images corresponding to magenta, cyan, and yellow are exposed by the second to fourth image forming mechanisms 16 to 18 in the same manner as the first image forming mechanism 15 described above. Full-color image formation is performed by developing on the body drum 25 and sequentially and repeatedly transferring onto the intermediate transfer belt 14c without positional deviation.

  As shown in FIG. 1, the secondary transfer mechanism 19 is constituted by a secondary transfer roller in this embodiment, and is disposed at a secondary transfer position on the vertical conveyance path 12. The secondary transfer position refers to a position where the secondary transfer mechanism 19 faces the driving roller 14a of the belt conveyance mechanism 14 and presses against the intermediate transfer belt 14c. A secondary transfer bias is applied to the secondary transfer mechanism 19, and an intermediate transfer belt is applied to the sheet P conveyed by the secondary transfer mechanism 19 via the vertical conveyance path 12 and the registration roller pair 13. A full color image is secondarily transferred from 14c.

  Then, the paper P after the secondary transfer of the full color image is separated from the intermediate transfer belt 14 c and conveyed to the fixing mechanism 20. The fixing mechanism 20 includes a first fixing roller 20a and a second fixing roller 20b. Each of the fixing rollers 20a and 20b includes a fixing heater (not shown) for heating to a predetermined temperature necessary for fixing. As a result, when the paper P passes while being pressed between the fixing rollers 20a and 20b, a fixing process of a full-color image is performed. Thereafter, the paper P is discharged from the fixing mechanism 20 to the discharge tray 22 via the discharge conveyance path 21.

  As shown in FIG. 1, the intermediate transfer cleaning unit 23 is configured by accommodating an intermediate transfer cleaning roller 23b, an intermediate transfer cleaning blade 23c, and a conveying screw 23d in a cleaning case 23a. The intermediate transfer cleaning roller 23b is pressed against the intermediate transfer belt 14c of the belt transport mechanism 14 and rotated in the same direction at a position opposite to the rotation direction of the intermediate transfer belt 14c by a drive motor (not shown). The intermediate transfer cleaning blade 23c is counter-contacted with the intermediate transfer belt 14c at a position downstream of the intermediate transfer cleaning roller 23b in the moving direction of the intermediate transfer belt 14c, and a liquid transfer residue from above the intermediate transfer belt 14c. Scrape off the liquid developer. The transport screw 23d collects the transfer residual liquid developer scraped off by the intermediate transfer cleaning blade 23c at the lower part in the cleaning case 23a.

Next, a specific configuration of the liquid developing device 28 in the first image forming mechanism 15 will be described with reference to FIG.
The liquid developing device 28 of this embodiment includes a liquid developer storage container 36 as a case for storing the liquid developer 35. Inside the liquid developer storage container 36, a developing roller 37 as a liquid developer carrier, a coating roller 38 as a transport roller, a pumping roller 39 as a transport roller, a doctor blade 40, a developing cleaning blade 41, and an agitation A pair of stirring screws 42 and 43 as members are provided. The developing roller 37, the application roller 38, the pumping roller 39, and both the agitating screws 42 and 43 are rotationally driven by a drive motor 73 described later via a drive transmission mechanism 72 including a gear train.

  The liquid developer 35 is adjusted so that the toner is dispersed at a high concentration in a carrier liquid made of a nonpolar insulating liquid such as silicon oil. The agitation screws 42 and 43 circulate and agitate the liquid developer 35 in the liquid developer storage container 36. The pumping roller 39 is rotated in contact with the application roller 38 in a state where a part of the pumping roller 39 is immersed in the liquid developer 35, and the liquid developer 35 is pumped up and applied to the application roller 38.

  The application roller 38 applies a liquid developer 35 onto the development roller 37, thereby forming a thin layer of the liquid developer 35 on the development roller 37. In the developing area on the photosensitive drum 25, the latent image is developed by the liquid developer 35. Further, the liquid developer 35 remaining on the developing roller 37 after the development is removed from the developing roller 37 by the developing cleaning blade 41 and returned to the liquid developer storage container 36.

  As shown in FIG. 2, the cleaning mechanism 30 includes a cleaning case 45 that accommodates the collected transfer residual liquid developer. Inside the cleaning case 45, a cleaning roller 46, a cleaning blade 47, and a conveying screw 48 are provided. The cleaning roller 46 is in pressure contact with the photosensitive drum 25 and is driven to rotate in the same direction as the photosensitive drum 25 at a contact portion by a drive motor (not shown). The cleaning blade 47 counter-contacts the photoconductive drum 25 below the cleaning roller 46 to collect and remove the transfer residual liquid developer on the photoconductive drum 25, so that the photoconductive drum 25 is subjected to the next image formation. Prepare for the process. The conveying screw 48 collects the transfer residual liquid developer scraped off by the cleaning blade 47 at the lower part in the cleaning case 45.

Next, a liquid developer supply path, a carrier liquid supply path, a transfer residual liquid developer reflux path, and a liquid developer disposal path in the wet image forming apparatus will be described with reference to FIG.
Here, the liquid developer supply path and the carrier liquid supply path are for supplying the liquid developer and the carrier liquid for supply to the liquid developing devices 28 of the first to fourth image forming mechanisms 15 to 18. . The recirculation path of the transfer residual liquid developer is for returning the transfer residual liquid developer collected by each cleaning mechanism 30 to the liquid developing device 28. Further, the liquid developer discard path is for collecting and discarding the transfer residual liquid developer of the intermediate transfer cleaning unit 23.

  Above the belt conveyance mechanism 14, first to fourth storage tanks 51, 52, 53, 54 are arranged. The first to fourth storage tanks 51 to 54 are for black, magenta, cyan, and yellow from the left side in FIGS. 1 and 3. Each of the storage tanks 51 to 54 stores a replenishing liquid developer concentrated more than the liquid developer 35.

  The liquid developer supply path of the first storage tank 51 includes a pipe 55 made of a tube connected between the first storage tank 51 and the liquid developer storage container 36 of the liquid developing device 28, and An electromagnetic on-off valve 56 provided in the pipe 55 is configured. When the toner concentration in the liquid developer storage container 36 decreases, the electromagnetic opening / closing valve 56 is controlled to open, and the liquid developer for replenishment is transferred from the first storage tank 51 to the liquid developer storage container 36. Is supplied by its own weight drop. The liquid developer may be supplied by a pump.

  A carrier liquid tank 57 is detachably attached to a main body frame (not shown) of the wet image forming apparatus so as to be positioned above the belt conveyance mechanism 14 adjacent to the first storage tank 51. The carrier liquid supply path corresponding to the first storage tank 51 includes a main pipe 58 connected to the carrier liquid tank 57, a branch pipe 59 branched from the main pipe 58 and connected to the liquid developer storage container 36. , And an electromagnetic on-off valve 60 provided in the branch pipe 59. When the liquid developer 35 in the liquid developer storage container 36 is insufficient, the electromagnetic opening / closing valve 60 is controlled to open, and the carrier liquid falls from the carrier liquid tank 57 to the liquid developer storage container 36 due to its own weight drop. Supplied. In addition, you may make it supply this carrier liquid with a pump.

  In this embodiment, the first storage tank 51, the pipe line 55, the electromagnetic on-off valve 56, and the like constitute a replenishing liquid developer replenishing means. The carrier liquid tank 57, the main pipe 58, the branch pipe 59, the electromagnetic on-off valve 60, and the like constitute carrier liquid replenishing means.

  The liquid developer supply paths of the second to fourth storage tanks 52 to 54 and the corresponding carrier liquid supply paths are the same as the liquid developer supply path and the carrier liquid supply path of the first storage tank 51. Therefore, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 3, a reflux pipe 61 as a reflux path is connected between the cleaning case 45 of each cleaning mechanism 30 and the liquid developer storage container 36 of each liquid developing device 28. Then, the recovered transfer residual liquid developer is refluxed to the liquid developer storage container 36 of the liquid developing device 28 via the reflux line 61 by driving the conveying screw 48 of the cleaning mechanism 30.

  A waste liquid tank 63 is connected to the cleaning case 23a of the intermediate transfer cleaning unit 23 via a waste liquid conduit 62 as a liquid developer disposal path. Then, the transfer residual liquid developer collected by the conveying screw 23 d of the intermediate transfer cleaning unit 23 is discarded into the waste liquid tank 63 via the waste liquid pipe 62.

  A waste pipe 64 is branched and connected in the middle of each reflux pipe 61 so that the transfer residual liquid developer collected by each cleaning mechanism 30 is guided to the waste liquid tank 63. An electromagnetic switching valve 65 constituting switching means is disposed at a branch portion between the reflux pipe 61 and the waste pipe 64, and the collected transfer residual liquid developer is switched to the liquid developing device 28 or the waste liquid tank 63 and supplied. Like to do.

  As shown in FIGS. 1 to 3, the toner as a toner concentration detecting means for detecting the concentration of toner contained in the carrier liquid of the liquid developer 35 is stored in the liquid developer storage container 36 of the liquid developing device 28. A density sensor 66 is provided. The liquid developer storage container 36 is provided with a liquid level sensor 67 as liquid level detecting means for detecting the liquid level (liquid level height) of the liquid developer 35.

Next, a specific configuration of the liquid developing device 28, which is a characteristic configuration of the present invention, will be described with reference to FIGS.
In the liquid developing device 28, the coating roller 38 that contacts the developing roller 37 among the coating roller 38 and the scooping roller 39 that constitute the transport roller has both side walls of the liquid developer storage container 36 via the support shaft 71. It is supported so as to be rotatable and movable in the axial direction. A drive transmission mechanism 72 composed of a gear train or the like is connected to one end of the support shaft 71, and the application roller 38 is rotated by the drive motor 73 via the drive transmission mechanism 72.

  At one end of the support shaft 71, an operating cam 74 constituting an operating means is disposed oppositely and is rotated by an operating motor 75 constituting the operating means. A spring 76 is joined to the other end of the support shaft 71, and the application roller 38 is moved and urged toward the operating cam 74 by the spring 76, so that one end of the support shaft 71 is brought into contact with the cam surface 74 a of the operating cam 74. It is in pressure contact. Then, when the operation cam 74 is rotated by the operation motor 75, the application roller 38 is reciprocated in a predetermined stroke in the axial direction by the cam action of the cam surface 74a.

  In this embodiment, the outer peripheral surface of the application roller 38 that can reciprocate is formed of a rigid material such as metal or ceramic, and the outer peripheral surface of the developing roller 37 that contacts the application roller 38 is the application roller 38. It is made of an elastic material such as rubber having a different material.

  Further, as shown in FIG. 6, when the length of the developing roller 37 is L1, the length of the coating roller 38 is L2, and the length of the pumping roller 39 is L3, these lengths are L1> L2> L3. In other words, the rollers arranged from the upstream side to the downstream side along the supply direction of the liquid developer 35 are set to become gradually longer. Further, the length L2a between both ends including the amount of reciprocation of the application roller 38 is shorter than the length L1 of the downstream developing roller 37 in contact with the application roller 38. The developing roller 37 is reciprocated at positions between both ends of the downstream developing roller 37.

Next, the operation of the liquid developing device 28 configured as described above will be described.
When the liquid developing device 28 is operated, the pumping roller 39, the application roller 38, and the developing roller 37 are rotated in the direction of the arrow in FIG. 2, and the liquid developer 35 in the liquid developer storage container 36 is moved to the rollers 39, 38. , 37 to be supplied onto the photosensitive drum 25. At this time, the actuation cam 74 is rotated by the actuation motor 75, and the application roller 38 is reciprocated in the axial direction by the cam action of the cam surface 74a. As a result, a uniform thin layer of the liquid developer 35 with no layer unevenness is formed in the axial direction between the application roller 38 and the developing roller 37, and the thin layer adheres onto the photosensitive drum 25. Therefore, the electrostatic latent image on the photosensitive drum 25 can be stably visualized.

  Further, since the outer peripheral surface of the application roller 38 is formed of a material different from the outer peripheral surface of the developing roller 37, the rollers 38 and 37 are relatively moved in the axial direction in a contact state without being damaged. . Therefore, it is possible to effectively suppress the occurrence of layer unevenness in the circumferential direction in the thin layer of the liquid developer 35 formed between the rollers 38 and 37. Incidentally, when both the outer peripheral surface of the application roller 38 and the outer peripheral surface of the developing roller 37 are formed of a rubber-like elastic body, the friction coefficient between them becomes high and smooth in the axial direction. It is difficult to obtain movement, and when both are made of metal, both are damaged by scratches such as scratches.

  Further, since the application roller 38 is reciprocated between the both ends of the downstream developing roller 37, an oversupply layer of the liquid developer 35 is formed at both ends of the upstream application roller 38. However, the excessive supply layer is pushed and extended by the reciprocating motion of the application roller 38 in the axial direction. Therefore, it is possible to prevent the possibility that the excessive supply layer of the liquid developer 35 is supplied onto the developing roller 37 to cause problems such as liquid leakage and image deterioration.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with a focus on differences from the first embodiment.

  In the liquid developing device 28 according to the second embodiment, as shown in FIGS. 7 and 8, anilox having a large number of block-like patterns on the outer peripheral surface between the pumping roller 39 and the coating roller 38. A roller 77 and a conveying roller 78 whose outer peripheral surface is made of an elastic material such as rubber are arranged. As in the case of the first embodiment, the outer peripheral surface of the application roller 38 that contacts the developing roller 37 is formed of a rigid material such as metal or ceramic, and the application roller 38 is the same as that of the first embodiment. The mechanism including the operation cam 74 is reciprocated with a predetermined stroke in the axial direction.

  Accordingly, also in the second embodiment, as in the first embodiment, the liquid developer 35 formed between the application roller 38 and the development roller 37 is reciprocated in the axial direction of the application roller 38. It is possible to suppress the occurrence of layer unevenness in the axial direction in the thin layer.

  Further, since the anilox roller 77 is provided in the supply path of the liquid developer 35, there is a possibility that a specific pattern or bubbles of the anilox roller 77 may be generated in the thin layer of the liquid developer 35. Are crushed and erased by the reciprocating motion of the coating roller 38 disposed on the downstream side in the axial direction. Accordingly, it is possible to suppress the possibility that the pattern of the anilox roller 77 appears in the image visualized on the photosensitive drum 25 or the generation of bubbles, and a good image can be obtained.

(Third embodiment)
Next, a third embodiment of the present invention will be described with a focus on differences from the first embodiment.

  In the liquid developing device 28 according to the third embodiment, as shown in FIGS. 9 and 10, a charging roller 79 is disposed on the outer peripheral surface of the developing roller 37 so as to be rotatable in contact with the developing roller 37. A predetermined charge is applied to the roller 37. In this embodiment, instead of the application roller 38 of the first embodiment, the charging roller 79 is reciprocated with a predetermined stroke in the axial direction by a mechanism including the operation cam 74 as in the first embodiment. It has come to be.

Therefore, also in the third embodiment, substantially the same effect as that of the first embodiment can be obtained.
(Example of change)
In addition, this embodiment can also be changed and embodied as follows.

  In the first and second embodiments, among the plurality of transport rollers arranged in the supply path of the liquid developer 35, the plurality of rollers that are not in contact with each other are reciprocated with a predetermined stroke in the axial direction. To be configured.

  In the third embodiment, the charging roller 79 is formed long in the axial direction so that both ends of the charging roller 79 are always located outside both ends of the developing roller 37, and the reciprocating stroke of the charging roller 79 is set. To do.

  Similarly, in the third embodiment, both ends of the charging roller 79 are configured to move between the outside of the both ends of the developing roller 37 and the inside thereof.

1 is a schematic configuration diagram of a wet image forming apparatus according to an embodiment embodying the present invention. FIG. 2 is a schematic front view of a first image forming mechanism in the wet image forming apparatus of FIG. 1. FIG. 3 is a block circuit diagram showing a liquid developer supply path, a liquid developer discard path, a carrier liquid supply path, and the like of the wet image forming apparatus. FIG. 2 is a schematic perspective view showing a first embodiment of an arrangement configuration of rollers of a liquid developing device. FIG. 3 is a cross-sectional view of a main part showing an operation configuration of a coating roller in the liquid developing device. FIG. 3 is a schematic front view of an arrangement configuration of rollers of a liquid developing device. Sectional drawing which shows the liquid developing device of 2nd Embodiment. FIG. 3 is a schematic perspective view illustrating an arrangement configuration of rollers of the liquid developing device. Sectional drawing which shows the liquid developing device of 3rd Embodiment. FIG. 3 is a schematic perspective view illustrating an arrangement configuration of rollers of the liquid developing device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 15-18 ... Image forming mechanism, 25 ... Photosensitive drum, 28 ... Liquid developing device as a developing device, 35 ... Liquid developer, 36 ... Liquid developer storage container as a case, 37 ... Developing roller, 38 ... Conveying roller Application roller 39 as a drawing roller as a conveyance roller 74 Operation cam constituting an operation means 75 Operation motor constituting an operation means 77 77 Anilox roller as a conveyance roller 79 79 Charging roller L1 , L2, L2a, L3... Length of the roller.

Claims (4)

In a developing device in which a liquid developer stored in a lower part of a case is supplied to a developing roller through a plurality of conveying rollers to visualize an electrostatic latent image, at least one conveying roller is arranged along an axial direction thereof. And a developing device provided with operating means for reciprocating at a predetermined stroke. The developing device according to claim 1, wherein the reciprocating transport roller is shorter than a downstream roller in contact with the transport roller and reciprocated at a position between both ends of the downstream roller. The developing device according to claim 1, wherein the transport roller that is reciprocated is made of a material different in outer peripheral surface from the outer peripheral surface of another roller in contact with the transport roller. A charging roller is disposed so as to contact the developing roller, and instead of the reciprocating transport roller, the charging roller is reciprocated with a predetermined stroke in an axial direction by an operating means. Item 4. The developing device according to any one of Items 3 to 3.

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