JP2005315952A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus whose structure is simple, also which prevents the possibility of liquid developer leaking out from a storage tank to the outside, and where liquid developer in the storage tank is stirred/mixed effectively. <P>SOLUTION: The image forming apparatus is equipped with a liquid development device 28 for forming an image with the liquid developer and storage tanks 51 to 54 for storing the liquid developer supplied to the liquid developer storage container 36 of the liquid development device 28. A stirring operation imparting mechanism 73 for imparting operation, such as rocking motion and linear movement for stirring the liquid developer to the storage tanks 51 to 54, is provided to the outside of the storage tanks 51 to 54. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to 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, whereby a toner image is formed on the photosensitive drum. The liquid developer stored in the liquid developer storage container is stirred and mixed by a stirring screw, and applied to the outer peripheral surface of the developing roller by a supply roller and an application roller.

  Further, when the amount of liquid developer stored in the liquid developer storage container becomes equal to or less than a predetermined amount due to the application of the liquid developer to the photosensitive drum as described above, the liquid developer replenishing device removes the liquid from the storage tank. A liquid developer is supplied to the developer storage container. At the same time, the carrier liquid is supplied from the carrier liquid tank to the liquid developer storage container by the carrier liquid supply device.

  By the way, in the image forming apparatus having such a configuration, while the liquid developer is stored in the storage tank, the liquid developer is separated and precipitated, and the liquid developer having a predetermined concentration is stored in the liquid developer. There was a problem that the container was not refilled. Therefore, in the conventional apparatus, a stirring screw is rotatably disposed inside the storage tank, and the stirring screw is directly connected to a drive motor provided outside the storage tank. The liquid developer stored in the storage tank is agitated and mixed by being rotated.

  However, in this conventional apparatus, it is necessary to provide a stirring screw in the storage tank, and there is a problem that the structure becomes complicated. In addition, since the stirring screw in the storage tank is directly connected to the drive motor outside the storage tank via the shaft portion that penetrates the side wall of the storage tank, the liquid developer in the storage tank passes through the shaft portion of the stirring screw. There was also a problem that it was easy to leak outside through the location.

In order to cope with such a problem, for example, an image forming apparatus having a configuration as disclosed in Patent Document 1, for example, has been proposed. That is, in this conventional apparatus, a non-contact type magnetic clutch is interposed between the stirring screw in the storage tank and the drive motor outside the storage tank, and the stirring screw is rotated by the drive motor via the magnet clutch. It is like that.
JP-A-5-241453

  However, in this conventional image forming apparatus, it is necessary to provide a stirring screw in the storage tank and to provide a magnet clutch between the stirring screw and the drive motor, so that the structure remains complicated. In addition, since the rotation of the drive motor is transmitted to the stirring screw via a non-contact type magnetic clutch, a large torque cannot be transmitted from the driving motor to the stirring screw. There was a problem that the liquid developer in the storage tank could not be sufficiently stirred and mixed because it could not be rotated with a large driving force.

  The present invention has been made paying attention to such problems existing in the prior art. Its purpose is simple in structure, it can prevent the liquid developer from leaking out of the storage tank, and the liquid developer in the storage tank can be effectively stirred and mixed. An object of the present invention is to provide an image forming apparatus capable of performing the above.

  In order to achieve the above object, the invention according to claim 1 is a storage unit for storing a developing unit for forming an image with a liquid developer and a liquid developer supplied to the developing unit. An image forming apparatus having a tank is characterized in that stirring operation applying means for applying an operation for stirring the liquid developer to the storage tank is provided.

According to a second aspect of the present invention, in the first aspect of the present invention, the stirring operation applying means swings the storage tank.
According to a third aspect of the present invention, in the first aspect of the present invention, the stirring operation applying means linearly moves the storage tank.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the stirring operation applying means vibrates the storage tank.
The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the storage tank is installed on a pedestal, and the storage tank is It is characterized by operating integrally.

  According to invention of Claim 1, it is not necessary to provide stirring members, such as a stirring screw, in a storage tank, and a structure can be simplified. Further, since the shaft portion of the agitation screw does not penetrate the side wall of the storage tank, it is possible to prevent the liquid developer from leaking out of the storage tank through the penetration portion of the shaft portion. Furthermore, since the agitation operation is applied to the entire storage tank from the outside, the liquid developer in the storage tank can be effectively agitated and mixed unlike the configuration in which the magnet clutch is provided.

  According to the second aspect of the present invention, the liquid developer in the storage tank can be effectively stirred and mixed by swinging the storage tank. Further, as the storage tank swings, a moving force toward the supply port on the inner bottom surface of the storage tank is applied to the liquid developer inside, so that the liquid developer in the storage tank is completely left without remaining. Can be supplied.

According to the third aspect of the present invention, the liquid developer in the storage tank can be effectively stirred and mixed by moving the storage tank linearly.
According to the fourth aspect of the present invention, the liquid developer in the storage tank can be effectively stirred and mixed by vibrating the storage tank.

  According to the fifth aspect of the present invention, the installation configuration of the storage tank is simple, and the storage tank can be operated integrally with the base so that the liquid developer can be effectively stirred and mixed.

(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 includes a primary transfer mechanism 29, a cleaning mechanism 30, and a static elimination lamp 31. 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 becomes approximately a replacement character. 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, 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 photosensitized 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 transport 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 paper 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. Thus, when the paper P passes while being pressed between the fixing rollers 20a and 20b, a fixing process for 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 is rotated in the same direction as the rotation direction of the intermediate transfer belt 14c by a drive motor (not shown). The intermediate transfer cleaning blade 23c is in counter contact 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 the liquid transfer residue is transferred from the intermediate transfer belt 14c. The liquid developer is scraped off and removed. 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 that stores the liquid developer 35. Inside the liquid developer storage container 36, a developing roller 37 as a liquid developer carrying member, a coating roller 38, a pumping roller 39, a doctor blade 40, a developing cleaning blade 41, and a pair of stirring screws 42 as stirring members, 43 is provided. The developing roller 37, the application roller 38, the scooping roller 39, and both the agitating screws 42 and 43 are rotationally driven by a drive motor (not shown) via a drive transmission mechanism 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, and 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 flexible and elastic tube connected between the first storage tank 51 and the liquid developer storage container 36 of the liquid developing device 28. The pipe 55 is constituted by an electromagnetic on-off valve 56 provided in the pipe 55. When the toner concentration in the liquid developer storage container 36 decreases, the electromagnetic on-off 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. 35 is supplied by its own weight drop. The liquid developer 35 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 is dropped from the carrier liquid tank 57 to the liquid developer storage container 36 by its own weight drop. Supply. 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 a carrier liquid supply 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 recovered by the transport screw 23 d of the intermediate transfer cleaning unit 23 is disposed of in the waste liquid tank 63 via the waste liquid conduit 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 characteristic configuration of the present invention will be described with reference to FIG.
On a main body frame (not shown) of the wet image forming apparatus, a pedestal 71 for installing the storage tanks 51 to 54 is disposed so as to be swingable around a support shaft 72 at one lower side. And each storage tank 51-54 is installed in this base 71 so that attachment or detachment is possible.

  On the other lower side of the pedestal 71, an agitation operation applying mechanism 73 as an agitation operation applying means for applying an operation for agitating the liquid developer to the storage tanks 51 to 54 is opposed to the storage tank 51-54. The stirring operation applying mechanism 73 includes a drive motor 74 and an eccentric cam 75 attached to the motor shaft of the drive motor 74 so as to contact the lower surface of the pedestal 71. Then, when the eccentric cam 75 is rotated by the drive motor 74, the base 71 and the storage tanks 51 to 54 are rocked integrally around the support shaft 72. As a result, the liquid developer stored in the storage tanks 51 to 54 is rippled and stirred and mixed without being separated and settled on the inner bottom.

  Therefore, in this wet image forming apparatus, it is not necessary to provide a stirring member such as a stirring screw in the storage tanks 51 to 54, and the structure can be simplified. Further, since the shaft portion of the agitation screw is not penetrated in the side walls of the storage tanks 51 to 54, there is no possibility that the liquid developer leaks from the inside of the storage tanks 51 to 54 through the penetration portion of the shaft portion.

  Furthermore, since the entire storage tanks 51 to 54 are swung from the outside by the stirring operation imparting mechanism 73 and the liquid developer inside thereof is swung, the liquid developer is effectively stirred and mixed. And separation / precipitation of the liquid developer can be reliably suppressed. Further, even when the liquid developer in the storage tanks 51 to 54 is reduced, the supply port 76 side of the inner bottom surface of the storage tanks 51 to 54 with respect to the liquid developer is accompanied by the swinging motion of the storage tanks 51 to 54. A moving force toward is provided. Therefore, the liquid developer in the storage tanks 51 to 54 can be completely supplied to the liquid developer storage container 36 of the liquid developing device 28 without remaining.

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

  In the second embodiment, as shown in FIG. 5, a pedestal 71 is arranged on a main body frame (not shown) so as to be linearly movable in a horizontal plane. Further, the stirring operation imparting mechanism 73 includes a drive motor 74 and an eccentric cam 75, and the eccentric cam 75 is in contact with the projecting piece 77 on the lower surface of the base 71. A spring 78 is interposed between the projecting piece 77 and the main body frame, and the projecting piece 77 is held in a state of being joined to the outer peripheral surface of the eccentric cam 75 by the biasing force of the spring 78.

  Then, when the eccentric cam 75 is rotated by the drive motor 74, the base 71 and the storage tanks 51 to 54 are linearly reciprocated integrally within a horizontal plane. Thereby, the liquid developer stored in the storage tanks 51 to 54 is waved and stirred and mixed. Therefore, also in the second embodiment, substantially the same effect as in the first embodiment can be obtained.

(Example of change)
In addition, this embodiment can also be changed and embodied as follows.
The stirring operation applying mechanism 73 is configured by a vibrator, and the vibrator is applied to the storage tanks 51 to 54 by the vibrator so that the liquid developer is stirred and mixed.

  -Instead of the configuration using the cam as the configuration for swinging or linearly moving the storage tanks 51 to 54, use another configuration, for example, a link mechanism.

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. 2 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. Sectional drawing which shows 1st Embodiment of the stirring operation provision structure of the liquid developer with respect to a storage tank. Sectional drawing which similarly shows 2nd Embodiment of the stirring operation provision structure of a liquid developer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 15-18 ... Image forming mechanism, 28 ... Liquid developing device as developing means, 35 ... Liquid developer, 36 ... Liquid developer storage container, 37 ... Developing roller, 51-54 ... Storage tank, 71 ... Base, 73 ... An agitation operation applying mechanism as an agitation operation applying means, 74... Drive motor, 75.

Claims (5)

In an image forming apparatus having a developing unit for forming an image with a liquid developer and a storage tank for storing a liquid developer supplied to the developing unit, the liquid developer with respect to the storage tank An image forming apparatus provided with an agitation operation applying means for applying an operation for agitation. The image forming apparatus according to claim 1, wherein the stirring operation applying unit swings the storage tank. The image forming apparatus according to claim 1, wherein the stirring operation applying unit moves the storage tank linearly. The image forming apparatus according to claim 1, wherein the stirring operation applying unit vibrates the storage tank. The image forming apparatus according to claim 1, wherein the storage tank is installed on a pedestal, and the pedestal operates to operate the storage tank integrally.

Images