JP2005338732A - Wet image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wet image forming apparatus having simple constitution and preventing a situation that residual toner remaining after transfer scraped by a cleaning roller is left as it is for a long period on a peripheral surface member positioned on the peripheral surface of a rotating body and stuck thereto. <P>SOLUTION: The wet image forming apparatus is equipped with a cleaning blade 121 and the cleaning roller 123 coming into contact with an intermediate transfer belt 43 positioned on the peripheral surface of a driven roller 42 and cleaning the intermediate transfer belt 43. The cleaning blade 121 and the cleaning roller 123 are supported to freely separate from the intermediate transfer belt 43. <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, and the like.

  In a wet image forming apparatus, a cleaning blade is brought into contact with the surface of a latent image carrier in order to collect unused liquid developer (toner and carrier liquid) on the latent image carrier such as a photosensitive drum. The liquid developer is scraped off. As described above, a method of scraping unused liquid developer on the surface of the latent image carrier with a cleaning blade is generally performed. However, in the case of development using a liquid developer composed of a toner and a carrier liquid, in a process such as development transfer, the toner concentration of the liquid developer changes, the toner concentration increases, and the viscosity of the liquid developer increases. Arise.

  The liquid developer scraped off by the cleaning blade flows smoothly through the discharge path after being scraped off when the viscosity is low. However, when the viscosity increases, the liquid developer remains attached to the cleaning blade. Alternatively, when left for a long period of time, the scraped toner accumulates at the tip of the cleaning blade and remains attached (fixed). When toner collects at the tip of the cleaning blade in this manner, there is a problem that image formation is hindered and image abnormality occurs.

In order to solve this problem, in Patent Document 1, cleaning is performed by moving the scraper in the longitudinal direction of the cleaning blade to remove the toner fixed to the tip, or rotating a roller or a brush-like rotating member. The toner at the blade tip is removed.
JP 2001-296780 A

  However, the technique for removing toner deposited on the tip of the cleaning blade with a scraper or the like proposed in Patent Document 1 has a problem that the configuration becomes very complicated even if it is performed by a service person during maintenance or is automated. Also, any of the techniques proposed in Patent Document 1 can remove the toner accumulated at the tip of the cleaning blade. However, if the transfer residual toner adheres and the cleaning blade is in contact with a rotating body such as a latent image carrier and is not used for a long time, there is a problem that the toner adheres to the latent image carrier. There is a problem that the image formation is adversely affected.

  An object of the present invention is a wet type that has a simple configuration and can prevent residual transfer toner scraped off by a cleaning member from being left on and fixed to a peripheral member positioned on the peripheral surface of a rotating body for a long period of time. An object is to provide an image forming apparatus.

  In order to solve the above-mentioned problems, the invention according to claim 1 is a wet image forming apparatus including a cleaning roller that contacts a peripheral member positioned on the peripheral surface of the rotating body and cleans the peripheral member. The wet image is characterized in that the cleaning roller is slidably supported with respect to the circumferential member, and the cleaning roller is connected to a rotation driving means that rotates when the cleaning roller is separated from the circumferential member. The gist of the forming apparatus.

  According to a second aspect of the present invention, in the first aspect of the present invention, the cleaning blade according to the first aspect includes a cleaning blade that contacts the peripheral surface member and cleans the peripheral surface member together with the cleaning roller, and the cleaning blade is attached to the peripheral surface member. It is characterized by being supported so as to be freely separated.

  According to the first aspect of the present invention, the cleaning roller is rotated when it is separated from the peripheral surface member, so that the toner on the cleaning roller can be easily scraped off. As a result, the configuration is simple, and it is possible to prevent the transfer residual toner scraped off by the cleaning roller from being left on the peripheral surface member positioned on the peripheral surface of the rotating body for a long time and fixing. According to the second aspect of the present invention, the toner scraped to the peripheral member by the tip of the cleaning blade is also scraped by the tip of the cleaning blade and separated to the peripheral member by separating the cleaning blade from the peripheral member. The adhered toner is prevented from adhering to the peripheral surface member and fixing as it is.

Hereinafter, an embodiment in which the wet image forming apparatus of the present invention is embodied in a tandem color image forming apparatus (hereinafter simply referred to as an image forming apparatus) will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram of an image forming apparatus. The image forming apparatus includes a paper feeding unit 1, a vertical conveyance path 2, a registration roller pair 3, a belt conveyance unit 4, a first image forming unit 5, a second image forming unit 6, a third image forming unit 7, 4 image forming means 8, secondary transfer means 9, fixing means 10, discharge conveying path 11, discharge tray 14 and the like. The paper feed means 1 includes a paper feed cassette 1a and a pickup roller 1b, and transports the paper P in the paper feed cassette 1a to the vertical transport path 2 by the pickup roller 1b. The vertical conveyance path 2 conveys the conveyed paper P to the secondary transfer unit 9 via the registration roller pair 3.

  The belt conveying means 4 includes a driving roller 41, a driven roller 42 as a rotating body, and an endless intermediate transfer belt 43 stretched across the two rollers. The intermediate transfer belt 43 corresponds to a peripheral member located on the peripheral surface of the driven roller 42. The intermediate transfer belt 43 maintains an appropriate tension by the tension roller 44. In this state, the driving roller 41 receives driving force from a driving motor (not shown), and the outer peripheral speed of the photosensitive drum 51 in each image forming unit and the outer peripheral speed of the intermediate transfer belt 43 of the belt conveying unit 4 are constant. It is driven to become.

  The first to fourth image forming units 5 to 8 shown in FIG. 1 are for black (BK), magenta (M), cyan (C), and yellow (Y) from the left side in the figure, and are all substantially the same. It is a unit of composition. Here, for convenience of explanation, the configuration of the first image forming unit 5 will be described with reference to FIG. In other image forming units, the same components as those of the first image forming unit 5 are denoted by the same reference numerals. The first image forming means 5 includes a photosensitive drum 51, a main charging device 52, an LPH (LED PRINT HEAD) 53, a liquid developing device 54, a primary transfer means 55, a cleaning device 56, and a charge eliminating lamp 57. By assembling it into the housing made of the above, it becomes one unit and is attached to the apparatus main body (not shown).

  The photosensitive drum 51 is an amorphous silicon drum and is charged by the main charging device 52 so that the dark potential at the developing position is about 300V. The LPH 53 irradiates the surface of the charged photoconductive drum 51 with light corresponding to image information, whereby an electrostatic latent image is formed on the surface of the photoconductive drum 51. The photosensitive drum 51 corresponds to a latent image carrier. The LPH 53 is used to reduce the size of the unit, but an LSU (laser scanning unit) may be used.

  The liquid developing device 54 stirs and mixes a developer composed of toner and carrier so as to have a predetermined concentration, and this developer is statically applied to a portion of the photosensitive drum 51 irradiated with light by a developing roller 72 described later. The toner image is formed on the photosensitive drum 51 by applying to the electrostatic latent image.

  The photosensitive drum 51 has a dark potential of 300V, a developing bias of 200V, and a post-exposure potential of 20V. That is, the dark potential corresponds to the white portion of the image, the post-exposure potential corresponds to the black portion of the image, and this difference is a so-called contrast potential. The toner image obtained by developing the electrostatic latent image formed as described above is transferred to the intermediate transfer belt 43 of the belt conveying unit 4 in the nip with the primary transfer unit 55. In the present embodiment, the primary transfer means 55 uses a transfer roller, and a voltage having a polarity opposite to the surface potential of the photosensitive drum 51 is set in a range of −1000 to −1300 V and applied.

  The toner not transferred on the photosensitive drum 51 is scraped off by the rubber blade 56a of the cleaning device 56 in the next process. The photosensitive drum 51 is neutralized by a neutralizing lamp 57 so as to lower the residual potential on the surface and make it uniform, and thereafter, it is prepared for the next series of processes. The potential setting for image formation in this manner varies depending on the characteristics of the photosensitive drum 51, the toner performance, and the environment. The image forming apparatus develops images corresponding to magenta, cyan, and yellow on the photosensitive drum by the second to fourth image forming units 6 to 8 in the same manner as the first image forming unit 5. A full-color image is formed by sequentially repeating the transfer onto the intermediate transfer belt 43 without transfer.

  Here, the configuration of the liquid developing device 54 will be briefly described. As shown in FIG. 2, the liquid developing device 54 includes a storage tank 71 that stores the liquid developer 70. Inside the storage tank 71, a developing roller 72 as a developer carrier, a coating roller 73, a pumping pump 74, and the like are provided. The developing roller 72, the application roller 73, and the pumping pump 74 are rotationally driven by a drive motor (both not shown) through a drive transmission mechanism including a gear train and the like. The liquid developer 70 is adjusted so as to disperse the toner at a high concentration in the carrier liquid composed of a nonpolar insulating liquid such as silicon oil and the carrier liquid. The pump 74 draws up the liquid developer 70 and applies the liquid developer 70 to the application roller 73.

  Returning to FIG. 1 again, image formation after transfer will be described. In the present embodiment, the secondary transfer unit 9 includes a secondary transfer roller. The secondary transfer unit 9 is disposed at a secondary transfer position on the vertical conveyance path 2. The secondary transfer position is a position where the secondary transfer unit 9 faces the driving roller 41 and is pressed against the intermediate transfer belt 43. A secondary transfer bias is applied to the secondary transfer unit 9, and the paper P conveyed by the secondary transfer unit 9 from the intermediate transfer belt 43 through the vertical conveyance path 2 and the registration roller pair 3. A full-color image is secondarily transferred to the image. Thereafter, the paper P onto which the full-color image has been secondarily transferred is separated from the intermediate transfer belt 43 and conveyed to the fixing unit 10. The fixing unit 10 includes a first fixing roller 10a and a second fixing roller 10b. Each fixing roller includes a fixing heater (not shown), and the identification fixing heater is controlled to a predetermined temperature necessary for fixing. Due to this temperature, a full-color image is fixed on the paper P that is pressed and passed by both rollers. The paper P is discharged to the discharge tray 14 via the discharge conveyance path 11 after being fixed by the fixing unit 10.

  Next, the intermediate transfer cleaning unit 12 that is a feature of the present embodiment will be described in detail. As shown in FIGS. 3 and 4, the intermediate transfer cleaning unit 12 is provided in the vicinity of the driven roller 42 and includes a housing 120, a cleaning blade 121, a screw 122, a cleaning roller 123, and the like.

  Below the driven roller 42, a support shaft 126 for supporting the intermediate transfer cleaning unit 12 is provided on a frame (not shown) of the apparatus main body. A pair of support brackets 124 (only one is shown in FIGS. 3 and 4) are attached to both ends of the support shaft 126 so as to be swingable with the shaft center of the support shaft 126 as a swing center. Both ends of the housing 120 are integrally fixed to the tip of the support bracket 124.

  As shown in FIGS. 3 to 5, the housing 120 includes a top wall 120b, a bottom wall 120c, a side wall 120d that connects the top wall 120b and the bottom wall 120c, and a pair of the top wall 120b to the side wall 120d. It is comprised by the end wall 120e (refer FIG. 5), and is formed in the substantially box shape. The housing 120 has an opening 120a extending horizontally on the side opposite to the side wall 120d, that is, on the driven roller 42 side.

  A recess having an arcuate cross section is formed on the upper surface of the bottom wall 120c of the housing 120. A cleaning blade 121 is attached to the lower side surface of the opening 120a side that extends from the bottom wall 120c via a bracket 125 as shown in FIG. As shown in FIG. 3, the cleaning blade 121 is arranged in the longitudinal direction of the housing 120 so as to shield the lower side of the opening 120a.

  A pair of seal members 130 are fixed to both ends of the bracket 125 in the longitudinal direction. Each seal member 130 includes a notch step portion 132, and is in liquid-tight contact with the upper portion and end surface of each end portion of the cleaning blade 121 via the notch step portion 132 (see FIG. 5). Further, a liquid having a property of repelling the carrier liquid of the liquid developer is applied to the notch step portion 132 of the seal member 130 on the upper portion and the end surface of each end portion of the cleaning blade 121. Further, a liquid having a property of repelling the carrier liquid is applied to the side surface of the driven roller 42 of the seal member 130. When the carrier liquid is oil, an oil-repellent liquid is used as a liquid that repels the carrier liquid. When the carrier liquid is water, a water-repellent liquid is used.

  By arranging the seal member 130 as described above, the upper portion of the seal member 130 is arranged to extend upward from both ends of the cleaning blade 121. Further, the separation distance between the two seal members 130 is shorter than the width of the intermediate transfer belt 43.

Corresponding to the opening 120a, a cleaning roller 123 is horizontally disposed in the housing 120, and both ends thereof are rotatably supported by both end walls 120e.
The cleaning roller 123 is made of a nitrile resin rubber material (for example, NBR). The cleaning roller 123 abuts on the intermediate transfer belt 43 when the cleaning roller 123 is positioned at a first position to be described later, and is driven to rotate so as to polish the intermediate transfer belt 43 and on the intermediate transfer belt 43. Scrape off any residual toner.

  A cleaning roller blade 128 protrudes into the housing 120 from the inner surface of the side wall 120d and is disposed horizontally. The tip of the cleaning roller blade 128 is in contact with the entire circumferential surface extending in the longitudinal direction of the cleaning roller 123 as shown in FIGS. 3 and 4, and the cleaning roller 123 is opposite to the cleaning roller 123 as shown in FIG. When rotated in the clockwise direction, the toner on the cleaning roller 123 is scraped off.

  The intermediate transfer cleaning unit 12 has a first position (see FIG. 4) located at a position closest to the driven roller 42 when the image forming apparatus forms an image, with the support shaft 126 as a swing center. The image is not formed, and can be swung between a second position (see FIG. 3) separated (retracted) from the driven roller 42.

  On the side of the support bracket 124, an eccentric cam 150 is provided on a frame (not shown) of the apparatus main body so as to be rotatable so as to be in contact with the side portion of the intermediate transfer cleaning unit 12. As the eccentric cam 150 rotates, the intermediate transfer cleaning unit 12 can reciprocate between the first position and the second position by the cam profile of the cam surface 150a. The intermediate transfer cleaning unit 12 is urged so as to always contact the eccentric cam 150 by a spring or the like (not shown). The eccentric cam 150 is operatively connected to a motor, which is a drive source (not shown), and the intermediate transfer cleaning unit 12 can be reciprocated to the first position and the second position by the control of the motor of the control device 170. .

  The first cam and the second cam are not limited to the eccentric cam 150. The cams move linearly, and the housing 120 is swung, or the support bracket 124 is rotated forward and backward by a step motor or the like. It may be changed to a position.

  When the intermediate transfer cleaning unit 12 is positioned at the first position, the cleaning roller 123 can come into contact with the intermediate transfer belt 43. The shaft of the cleaning roller 123 is operatively connected to a screw 122, which will be described later, via a gear mechanism 162 (see FIG. 2B), and the gear mechanism 162 is operated by a drive motor 160 as a rotation driving means. It is connected. Then, as shown in FIG. 2B, the drive motor 160 is driven and controlled under the control of the control device 170. Then, the driving roller 160 drives the cleaning roller 123 via the gear mechanism 162 to rotate counterclockwise as shown in FIG.

  Further, when the intermediate transfer cleaning unit 12 is located at the first position, the tip of the cleaning blade 121 is brought into counter contact with the intermediate transfer belt 43. As a result, the transfer residual toner on the intermediate transfer belt 43 is collected and removed by the cleaning roller 123 and the cleaning blade 121, and the intermediate transfer belt 43 can be prepared for the next image forming process. When the counter is in contact, the intermediate transfer belt 43 is in contact with the tip of the cleaning blade 121 so as to be positioned between the seal members 130.

  As shown in FIGS. 3 and 4, a screw 122 is horizontally disposed in the housing 120. The shafts at both ends of the screw 122 are supported in a fluid-tight manner with respect to both end walls 120e. A shaft portion on one end side of the screw 122 protrudes from one end wall 120e, and a gear constituting a part of the gear mechanism 162 is fixed to the protruding end.

  The gear mechanism 162 is operatively connected to a gear centering on the axis of the support shaft 126, and the torque from the drive motor is always applied to the screw 122, even when the intermediate transfer cleaning unit 12 is swung. It can be transmitted to the cleaning roller 123.

  In the housing 120, a discharge port (not shown) is formed on one end side of the bottom wall 120c. The discharge port communicates with a waste toner bottle 140 provided on the bottom wall 120 c side of the housing 120, and the scraped toner and carrier liquid are discharged into the waste toner bottle 140 by driving the screw 122.

(Function)
Now, the operation of the image forming apparatus configured as described above will be described.
When printing is performed by the image forming apparatus, the control device 170 controls the rotation of the eccentric cam 150, and the intermediate transfer cleaning unit 12 (that is, the housing 120) shown in FIG. 4 is positioned at the first position. In this state, image formation (printing) is performed. At the time of image formation, the intermediate transfer belt 43 is moved, and as shown in FIG. 4, the cleaning roller 123 that is rotationally driven contacts the intermediate transfer belt 43, and the cleaning blade 121 is brought into contact with the counter. Then, the transfer residual toner and the carrier liquid on the intermediate transfer belt 43 are collected and removed. The cleaning roller 123 is rotationally driven via the gear mechanism 162 by the rotation of the drive motor 160.

  In this state, the screw 122 is rotationally driven via the gear mechanism 162 by the rotation of the drive motor 160. The recovered carrier liquid and toner of the liquid developer 70 are stored in the waste toner bottle 140 by a rotating screw 122 through a discharge port (not shown).

The toner scraped off by the cleaning roller 123 is scraped off by the cleaning roller blade 128 and falls into the recess of the bottom wall 120c below.
When printing is completed, the controller 170 controls the eccentric cam 150 to rotate the motor, and the intermediate transfer cleaning unit 12 is displaced from the first position to the second position as shown in FIG. 3 as shown in FIG. Let

  In this state, when the control device 170 controls the rotation of the drive motor 160, the cleaning roller 123 is rotationally driven via the gear mechanism 162. Due to the rotation of the cleaning roller 123, the toner scraped off by the cleaning roller 123 is scraped off by the cleaning roller blade 128 and falls into the recess of the bottom wall 120c below. As a result, after printing, the cleaning blade 121 and the cleaning roller 123 are separated (retracted) from the intermediate transfer belt 43. Therefore, the toner scraped off by the tip of the cleaning blade 121 and the cleaning roller 123 and attached to the intermediate transfer belt 43 is prevented from adhering to the intermediate transfer belt 43 and fixing as it is.

  When the tip of the cleaning blade 121 is in counter contact with the intermediate transfer belt 43, the intermediate transfer belt 43 is disposed between the seal members 130. For this reason, leakage of toner and carrier liquid from both ends in the longitudinal direction can be prevented at the front end (width direction front end) of the cleaning blade 121.

In addition, this invention is not limited to the said embodiment, You may change the said embodiment as follows.
In the above embodiment, the intermediate transfer cleaning unit 12 is displaced from the first position to the second position after the printing is finished. However, before the printing is performed, the intermediate transfer cleaning unit 12 is moved from the first position to the second position. Then, the cleaning roller 123 may be rotationally driven.

  In the above embodiment, the intermediate transfer cleaning unit 12 of the intermediate transfer belt 43 is embodied. However, for example, it may be embodied in the cleaning device 56 that removes the toner on the photosensitive drum 51 as a latent image carrier. In this case, the peripheral surface member is a member constituting the peripheral surface of the photosensitive drum 51.

  In the embodiment, the cleaning blade 121 and the cleaning roller 123 are provided, but either one may be omitted.

1 is a schematic configuration diagram of a wet image forming apparatus according to an embodiment of the present invention. (A) is the schematic of a 1st image formation means similarly, (b) is a control block diagram. FIG. 3 is a schematic cross-sectional view of the intermediate transfer cleaning unit. FIG. 3 is a schematic cross-sectional view of the intermediate transfer cleaning unit. FIG. 3 is a schematic perspective view of the intermediate transfer cleaning unit.

Explanation of symbols

12. Intermediate transfer cleaning unit (cleaning unit)
42 ... driven roller (rotating body)
43. Intermediate transfer belt (circumferential member)
121 ... Cleaning blade (cleaning member)
123 ... Cleaning roller (cleaning member)
160 ... Drive motor (rotation drive means)

Claims (2)

In a wet image forming apparatus provided with a cleaning roller that contacts a peripheral member positioned on the peripheral surface of the rotating body and cleans the peripheral member,
Wet image formation characterized in that the cleaning roller is supported so as to be separable from the circumferential member, and the cleaning roller is connected to a rotation driving means that rotates when the cleaning roller is separated from the circumferential member. apparatus.   A cleaning blade that contacts the peripheral member and cleans the peripheral member together with the cleaning roller is provided, and the cleaning blade is supported so as to be separated from the peripheral member. Item 2. The wet image forming apparatus according to Item 1.

Images