JPH10177304A - Wet image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize excess liquid removing performance even though a device is needed to be large and speeding-up is needed by providing an excess liquid- sucking means removing excess developer on a surface with width equal to or more than the width of an image producing area on the surface of a latent image carrier obtained after developing by suction. SOLUTION: A liquid-sucking device 5 is used as the excess liquid removing means removing the excess developer on the surface of a photoreceptor 1 after the developing. As to the liquid-sucking member 51 of the device 5; a slit thin groove 51a having length equal to or more than the width of the image producing area is formed to be opposed to the image producing area of the photoreceptor 1, and excess developer is sucked from the groove 51a. A sucked liquid tank 52 stores the liquid (sucked liquid) sucked by the member 51. Besides, a suction pipe 53 connects the groove 51a of the member 51 with the tank 52, and recovers the sucked liquid to the tank 52. In this case, the member 51 is set so that a specified fine gap is formed between the member 51 and the photoreceptor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet image forming apparatus such as a copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art Conventionally, a latent image is formed on the surface of a latent image carrier,
A developing roller in which a toner as a developer is dispersed in a liquid carrier is carried on a developing roller, the developing solution is transported by rotation of the developing roller, and supplied to the surface of the latent image carrier to develop the latent image. 2. Description of the Related Art There is known a wet image forming apparatus that forms a toner image on a transfer material and transfers the toner image to a transfer material. When a developing method of performing development using the developing roller is adopted,
An image can be satisfactorily formed even in a copying machine using a latent image carrier having no flexibility, for example, a rigid photosensitive drum such as aluminum. In the above-described wet image forming apparatus, the toner in the liquid carrier is used to attach toner to the surface of the latent image carrier during development or to move the toner from the surface of the latent image carrier to the transfer material during transfer. It utilizes the phenomenon of electrophoresis.

In such a wet image forming apparatus,
A developer layer having a thickness of 30 to 200 μm is formed on the surface of the photosensitive drum as a latent image carrier having passed through the developing area. In this state, even if the transfer material is transferred onto the surface of the latent image bearing member, the adhesion between the liquid layer and the transfer material is poor, so that a sufficient toner transfer rate cannot be obtained, and image leakage and thickening of characters occur. I do. On the other hand, if the amount of the carrier liquid layer is too small, the transfer by electrophoresis becomes difficult and the image density is reduced, or the image density is reduced only in the portion corresponding to the concave portion of the surface of the transfer material, or white dropout occurs. I do. Therefore, surplus carrier liquid is squeezed while leaving an appropriate amount of carrier liquid that does not cause such a problem.

As a method of squeezing excess carrier liquid, a squeeze roller as a means for removing excess liquid is disposed to face the photosensitive drum surface at a predetermined interval, and the squeeze roller is placed in a region facing the photosensitive drum. There are known methods of rotating the photosensitive drum in a direction opposite to the rotating direction, and applying a predetermined bias voltage to a squeeze roller. There is also known an air squeeze system in which wind blowing from a nozzle is applied to the surface of a latent image carrier, and the developer pressure on the surface of the photosensitive drum is blown by the wind pressure.

In the air squeezing method, it is difficult to make the liquid film thinner by overcoming the surface tension of the liquid on the surface of the photoreceptor drum. Excess liquid removal performance is not sufficient as compared with the method using the squeeze roller. For this reason, squeeze rollers having excellent surplus liquid removing performance are widely used.

In the method using the squeeze roller, the performance of removing excess liquid depends on the distance between the surface of the photosensitive drum and the surface of the squeeze roller and the movement between the surface of the photosensitive drum and the surface of the squeeze roller. Optimized by speed difference. And the above-mentioned removal performance increases as the interval becomes narrower, and in order to secure an appropriate removal performance, a variation in the interval between the surface of the photosensitive drum and the surface of the squeeze roller is reduced.
For example, it is necessary to keep it within about 20 μm and to keep the difference in moving speed between the surface of the photosensitive drum and the surface of the squeeze roller at an appropriate value. However, in a wet image forming apparatus using a method using a squeeze roller, if it is necessary to increase the length of the photoconductor drum to achieve high productivity and increase the size of the apparatus, it is impossible to match the length of the drum. Roller dimensions are required, and the dimensional accuracy of the photosensitive drum surface becomes severe. In addition, when high-speed rotation of the photosensitive drum is required to increase the speed of the apparatus, high-speed rotation of the squeeze roller is required to maintain the moving speed difference at an appropriate value.
An increase in device vibration occurs, and banding of an image occurs due to the increase in device vibration. Therefore, the method using the squeeze roller has a problem that it is difficult to properly optimize the surplus liquid removing performance when the apparatus needs to be increased in size or increased in speed.

The present invention has been made in view of the above problems, and an object of the present invention is to appropriately optimize surplus liquid removal performance even when a large-size or high-speed apparatus is required. It is to provide a wet image forming apparatus which can be used.

[0007]

In order to achieve the above object, a first aspect of the present invention is a latent image carrier having a latent image formed on a surface thereof, and a developer comprising a liquid carrier and a developer dispersed therein. And a developing roller for supplying a developing solution to the surface of the latent image carrier by rotation, and supplying the developing solution to the surface of the latent image carrier by the developing roller. Developing means for developing a developer image by developing the latent image carrier, and a surplus liquid removing means for removing a part of the liquid carrier adhered to the latent image carrier on which the developer image has been formed. A transfer unit for transferring the developer image from the latent image carrier to a transfer material, wherein the excess liquid removing unit includes a width not less than an image forming area width of the latent image carrier surface after development. The excess liquid suction means for removing the excess developer on the surface by suction It is characterized in that the digits.

According to a second aspect of the present invention, in the wet image forming apparatus of the first aspect, the surplus liquid suction means is provided with a predetermined gap from the latent image carrier, and the surface of the latent image carrier is provided. A developing solution suction member formed to face the image forming region with a slit narrow groove having a length equal to or longer than the image forming region width, and a developer sucking member for sucking the surplus developer from the slit narrow groove; And a liquid suction device having a negative pressure generating means for generating a negative pressure in the slit narrow groove in order to suction excess developer.

In these wet image forming apparatuses, the surplus liquid suction means is provided with a surplus developing solution, for example, a developer image portion, having a width equal to or larger than the width of the image forming area on the surface of the latent image carrier after development. Excess developer and the developer in the background are removed by suction. The performance of removing the excess liquid by the excess liquid suction means changes depending on the suction force of the excess developer by the excess liquid suction means. Therefore, by adjusting the suction force, it is possible to optimize the performance of removing the excess liquid by the excess liquid suction means.

According to a third aspect of the present invention, in the wet image forming apparatus of the first aspect, the surplus liquid suction means is provided at a predetermined gap from the latent image carrier, and the surface of the latent image carrier is formed. A slit narrow groove having a length equal to or more than the image area width is formed so as to face the image forming area, and a developing solution or a cleaning liquid is applied to the slit narrow groove so that the surface of the liquid contacts the surface of the latent image carrier. A developer sucking member for sucking the solution and the surplus developer while flowing the solution, a liquid supply means for supplying a developer or a cleaning solution to the slit narrow groove, and the developer and the surplus developer by the developer sucking member. A liquid suction device having negative pressure generating means for generating a negative pressure in the narrow slit for sucking the developing solution is provided.

In this wet image forming apparatus, the latent image carrier is provided with a predetermined gap therebetween, and the slit narrow groove having a length equal to or greater than the width of the image forming area on the surface of the latent image carrier is provided. A developing solution which is formed so as to face the body and which sucks the developing solution or the cleaning solution while flowing the developing solution or the cleaning solution through the slit narrow grooves so that the surface of the solution contacts the surface of the latent image carrier. A suction member, a liquid supply means for supplying a developing solution or a cleaning liquid to the slit narrow groove, and a negative pressure for generating a negative pressure in the slit narrow groove for sucking the liquid and excess developer by the developer sucking member. Using a liquid suction device having a pressure generating means, a developing solution or a cleaning solution is flowed through the slit narrow groove so that the surface of the liquid comes into contact with the surface of the latent image carrier. For example, surplus current in the developer image Performing suction of the developer liquid and the background portion.
Further, when the cleaning liquid is caused to flow through the slit narrow groove, the cleaning liquid is used to wash away the developer adhering to the portion other than the developer image on the surface of the latent image carrier, that is, the background portion.

According to a fourth aspect of the present invention, there is provided a liquid suction device for removing the surplus developer while circulating the cleaning liquid in a liquid circulation path including the developer suction member and the liquid supply means. 4. The wet image forming apparatus according to claim 3, further comprising a recovery device in the liquid circulation path for recovering the developer from the cleaning liquid, supplying the developer recovered by the recovery device to the developing unit for reuse. It is characterized in that a re-use means for causing the re-use is provided.

In this wet image forming apparatus, the liquid suction device removes the surplus developer while circulating the cleaning liquid through a liquid circulation path including the developer suction member and the liquid supply means. The developer mixed in the cleaning liquid is recovered by the recovery unit provided in the developer circulation system by the recycling unit, and the recovered developer is reused by the developing unit.

According to a fifth aspect of the present invention, in the wet image forming apparatus according to the second, third, or fourth aspect, the surface of the latent image carrier is formed while moving. A gap holding member that holds the gap between the developer suction member and the latent image carrier by bringing the convex portion into contact with the surface of the latent image carrier; , So as to be movable in the same direction.

In this wet image forming apparatus, the convexity of the surface of the gap holding member is brought into contact with the surface of the latent image carrier by the gap holding member so that the gap between the developer sucking member and the latent image carrier is formed. The small gap is maintained. At this time, a large number of convex portions on the surface of the gap holding member block the flow path of the air flowing toward the slit narrow groove, and the air flow toward the slit narrow groove is reduced as compared with a case where the large number of the convex portions are not provided. The flow rate of the flowing air decreases. Further, since the surface is movable in the same direction at a portion facing the surface of the latent image carrier, the convex portion comes into contact with the surface of the latent image carrier, and the convex portion forms a developer image on the surface of the latent image carrier. When the developer image is touched, it is possible to prevent the developer image from being scratched in a streak shape and the developer image from being rubbed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter, referred to as a copying machine) which is a wet image forming apparatus will be described. FIG. 1 is a schematic configuration diagram of a main part of a copying machine according to the present embodiment. The photosensitive drum 1 as a latent image carrier is driven to rotate at a constant speed in the direction of arrow a at the time of copying by driving means such as a motor (not shown). After the outer peripheral surface of the photosensitive drum 1 is charged in the dark by a main charger 2 as a charging unit,
The exposure device 3 irradiates and forms a light image of the original, and an electrostatic latent image is carried on the outer peripheral surface of the photosensitive drum 1. Next, the portion outside the image forming area on the outer peripheral surface of the photosensitive drum 1 is neutralized by an eraser (not shown). Thereafter, the electrostatic latent image is developed while passing through a portion of the wet developing device 4 as a developing unit, and becomes a toner image. Then, a surplus developing solution on the surface of the photoreceptor drum 1 after the development is removed by a liquid suction device 5 as surplus liquid removing means described later in detail. The toner image is transferred to a transfer sheet 7 as a transfer material fed from a sheet feeding device (not shown) in a transfer section 6. That is, the toner image is transferred to the photosensitive drum 1 and the transfer paper 7.
In the liquid carrier between the photosensitive drums 1
To the transfer paper 7. The photosensitive drum 1 is a transfer paper 7
After the separation, the residual developer is removed by the cleaning device 8 including the foam roller 8a and the cleaning blade 8b. The foam roller 8a rotates while supplying the photoconductor cleaning liquid to the surface of the photoconductor drum, wipes off the toner on the surface of the photoconductor drum 1, and collects the photoconductor cleaning liquid containing the toner. Then, the surface of the photosensitive drum 1 wiped by the foam roller 8a is further wiped by the cleaning blade 8b. The direction in which the cleaning blade 8b is disposed may be the trailing direction or the counter direction. Thereafter, the residual potential is removed from the surface of the photosensitive drum 1 by the charge removing lamp 9 to prepare for the next copy. The transfer paper 7 onto which the toner image has been transferred passes through a fixing device (not shown) and is discharged outside the apparatus.

The wet developing device 4 as a developing means is provided so as to be in close proximity to the photosensitive drum 1 and a developer tank 41 as a developer container for storing a developer 40 used for development. A developing roller 42, a tray-shaped developer receiving member 43 that receives the liquid after development and returns it to the developer tank 41, and a developing roller 42 from the developer tank 41.
And a developer supply means 46 having a pump 44 and a developer supply pipe 45 for supplying the developer to the printer. As the developing solution 40, a solution in which a toner as a developer is dispersed in a solvent (hereinafter, referred to as a developing solution solvent) 40a as a liquid carrier is used.

A developing bias voltage is applied to the developing roller 42 from a power source (not shown) to prevent the image on the photosensitive drum 1 from becoming dirty. Further, the developing roller 42 is driven to rotate by a drive motor (not shown) in a direction indicated by an arrow b which is a reverse rotation direction to the photosensitive drum 1. This developing roller 4
2, a scraper 47 is disposed with its end portion in contact with the outer peripheral surface of the developing roller 42. Then, the developing solution 40 is supplied from the developing solution tank 41 to the wedge-shaped portion 48 formed by the developing roller 42 and the scraper 47 by the developing solution supply means 46. The developing roller 42 is supplied to a developing section facing the developing roller 42.

A developing solution concentration sensor (not shown) for detecting the concentration of the developing solution in the developing solution tank 41 is provided in the developing solution tank 41. Liquid tank 44
A developer amount sensor (not shown) for detecting whether the height of the developing solution in the inside has reached a predetermined height, and a carrier bottle (not shown) for supplying a carrier solution to the developing solution tank 44 are provided. Then, when the developer concentration sensor detects that the toner has been consumed and the developer concentration in the developer solution tank 44 has decreased, the conc. Toner is supplied from the conc. Toner bottle to the developer solution tank 44. Also,
When the developer amount sensor detects that the height of the developer in the developer tank 44 is lower than a predetermined lower limit height, the carrier liquid is replenished from the carrier bottle to the developer tank 41. .

In the transfer section 6, a transfer roller 61 as a transfer charge applying means is provided to face the photosensitive drum 1 via a transfer belt 62 as a transfer material supporting member. A high voltage is applied to the transfer roller 61 from a power source (not shown) in order to form a transfer electric field.

In the copying machine according to the present embodiment, as described above, the liquid suction device 5 is used as an excess liquid removing means for removing the excess developer on the surface of the photosensitive drum 1 after development. Hereinafter, the liquid suction device 5 will be described in detail. The liquid suction device 5 removes the excess developer, specifically, the excess developer in the toner image portion and the developer in the background portion by suction. The liquid suction device 5 is formed such that a slit narrow groove 51 a having a length equal to or longer than the image forming area width is formed so as to face the image forming area of the photosensitive drum 1.
, A liquid suction member 51 as a developer suction member for sucking the excess developer, and a suction liquid tank 52 for storing the liquid sucked by the liquid suction member 51 (hereinafter referred to as a suction liquid).
And a suction pipe 53 for connecting the slit narrow groove 51a of the liquid suction member 51 to the suction liquid tank 52 and collecting the suction liquid in the suction liquid tank 52. The liquid suction member 5
1 is that if the photosensitive drum 1 comes into close contact with the surface of the photosensitive drum 1 during liquid suction, the rotation of the photosensitive drum 1 becomes impossible. Therefore, the photosensitive drum 1 is installed so as to have a predetermined minute gap. For example, a roller having an axis in the direction of the slit narrow groove, that is, the photoconductor axis direction, is attached to the liquid suction member 51 so that the roller contacts the non-image forming area of the photoconductor drum 1 and is rotatable. What is necessary is just to comprise so that the minute gap | interval between the suction member 5 and the photosensitive drum 1 may be maintained. The slit narrow groove 51a has a width of about several millimeters in a direction perpendicular to the photosensitive drum axis direction (horizontal direction in the figure) and a depth of 1 mm.
cm or less. The suction pipe 5
In the middle of 3, a suction pump 55 is connected as a negative pressure generating means for generating a negative pressure in the slit narrow groove 51a and sucking an excess developer with the liquid suction member 51. For example, a vacuum pump can be used as the suction pump. In the pipe connecting the suction pump 55 to the suction pipe 53, there is provided a liquid filter 54 that allows air to pass but does not allow liquid to pass.

In the copying machine shown in the drawing, the suction liquid is supplied to the developing means, and the suction liquid can be used again for development. Specifically, a circulation pipe 101 for connecting the suction liquid tank 52 and the developer tank 41 and supplying a suction liquid from the suction liquid tank 52 to the developer tank 41 is provided. For example, an electromagnetic valve 102 and the valve 10
Circulating pump 1 which is provided in the middle of a pipe connecting the developer tank 2 and the developer tank 41 and generates a negative pressure such that a developer flows from the suction tank 52 to the developer tank 41.
03 is provided, the suction device supplies the suction liquid to the developing unit, and the suction liquid is used again for development. (Hereinafter, margin)

When excess liquid developer on the surface of the photosensitive drum 1 is sucked by the liquid suction device 5 having the above structure, the valve 102 is tightened to increase the confidentiality inside the liquid suction device 5.
Then, air is sucked only from the gap G between the liquid suction member 51 and the surface of the photosensitive drum 1. In this state, when the suction pump 53 is operated so that the amount of air sucked by the suction pump 53 is larger than the amount of air sucked from the gap G, the slit narrow groove 51a is in a negative pressure state. Then, excess developer is sucked by the negative pressure. The sucked developer, that is, the suction liquid, passes through the suction pipe 53 and is stored in the suction liquid tank 52.

Then, the suction liquid collected in the suction liquid tank 52 is reused by the recycling device 100 at a predetermined timing, for example, when the level of the developing solution in the suction liquid tank 52 attached to the suction liquid tank 52 is raised. A developer level sensor (not shown) detects the developer level when the developer level reaches a predetermined height or every time a predetermined time elapses.
1 is supplied. When supplying liquid to the developer tank 41 in the recycling apparatus 100, the suction pump 5
The operation of step 5 is stopped, the valve 102 is opened, and then the circulation pump 103 is operated. And the circulation pump 1
The operation of 03 causes a flow of the developing solution from the suction solution tank 52 to the developing solution tank 41 in the circulation pipe 101, and the suction solution is supplied to the developing solution tank 41. The developer tank 41
Is mixed with the developing solution in the developing solution tank 41 and used for the developing operation. As described above, by using the suction liquid again for the developing operation, the developer can be effectively used, and the running cost can be reduced.

Using the liquid suction device 5, the photosensitive drum 1
When the surplus liquid on the surface is removed, the removal performance is determined by the negative pressure generated in the slit 51a of the liquid suction device 5. The negative pressure is determined by the amount of air flowing into the slit narrow groove 51a from the gap G between the liquid suction member 51 and the surface of the photosensitive drum 1 and the amount of air sucked by the suction pump 55. Specifically, the amount of air sucked by the suction pump 55 is changed from the gap G to the slit narrow groove 5.
The negative pressure increases as the amount of air flowing into 1a increases.
The amount of air sucked by the suction pump 55 changes depending on the negative pressure generating ability of the suction pump 55, and the amount of air flowing from the gap G into the slit narrow groove 51a changes depending on the size of the gap G. Specifically, the higher the negative pressure generating ability of the suction pump, the larger the amount of air sucked by the suction pump 55, and the smaller the gap G, the smaller the amount of air flowing from the gap G into the slit narrow groove 51a. The removal performance can be increased by increasing the negative pressure. From this, the liquid suction device 5
The removal performance can be optimized by adjusting at least one of the negative pressure generating capacity of the suction pump 55 and the gap G. Therefore, when it is difficult to optimize the removing performance by adjusting the gap G, the negative pressure generating ability can be adjusted to optimize the removing performance. Therefore, unlike the case where a squeeze roller is used, even when the apparatus needs to be increased in size or increased in speed, the removal performance can be properly optimized without causing any trouble. The removal performance can be enhanced by increasing the negative pressure generation ability. Therefore, by using a pump having an appropriate negative pressure generation ability, the removal performance can be sufficiently obtained and a good image can be formed. is there.

[Embodiment 2] Next, another embodiment will be described with reference to FIGS. FIG. 2 is a perspective view showing a schematic configuration of a copying machine according to the present embodiment. FIG. 3A is a perspective view showing a schematic configuration of a liquid suction device 5 of the copying machine.
(B) is an explanatory view of the liquid suction of the liquid suction device 5. In the present embodiment, a configuration basically similar to that of the first embodiment is provided. The difference from the configuration of the first embodiment is that the liquid suction device 5 is configured such that a developer or a cleaning liquid flows through the narrow slit so that the surface of the liquid contacts the surface of the latent image carrier. And that the excess developer is removed by suction. Hereinafter, the liquid suction device 5 will be described in detail.

The illustrated liquid suction device 5 includes a liquid suction member 51 similar to the liquid suction device 5 of the copying machine shown in FIG.
Liquid tank 1 as a liquid storage unit for storing a flowing liquid)
11 is provided. The liquid tank 111 also functions as the suction liquid tank 52 of the liquid suction device 5 of the copying machine shown in FIG. Further, the illustrated liquid suction device 5 is provided with the liquid tank 1.
A liquid circulation channel for circulating the flowing liquid between the liquid suction member 11 and the liquid suction member 51 is provided. The liquid circulation passage is provided with the liquid suction member 5.
A liquid supply pipe 11 for connecting one end of one of the slit narrow grooves 51a in the axial direction of the photosensitive drum to the liquid tank 111 and supplying a liquid flowing from the liquid tank 111 to the liquid suction member 51.
2, the other end of the slit narrow groove 51a of the liquid suction member 51 in the photosensitive drum axial direction and the liquid tank 111 are connected, and the liquid sucked by the liquid suction member 51, that is, the suction liquid, is It is constituted by a suction pipe 53 and the like to be collected in 111. Further, a suction pump 55 is provided in the middle of the suction pipe 53 as a negative pressure generating means for generating a negative pressure for circulating the flowing liquid in the liquid circulation channel. As the flowing liquid, a developing liquid or a cleaning liquid having a function of washing away toner adhered to the background portion of the photosensitive drum surface, for example, a developing liquid solvent 40a
Can be used. In the liquid suction device 5 of the illustrated example,
A developer solvent 40a is used as the flowing liquid.

In the copying machine according to the present embodiment, the toner is recovered from the developing solution solvent 40a as a flowing liquid in which the toner is mixed into the liquid circulation flow path by suctioning the liquid from the surface of the photosensitive drum 1. A recycling device 130 having a collecting device 131 is provided so that the toner collected by the collecting device 131 can be supplied to the developing unit and reused. Specifically, the collection device 1
31 removes the toner from the developer solvent 40a in which the toner is mixed, removes the toner from the developer solvent 40a and purifies the liquid (hereinafter referred to as a purifying solution), and removes the toner collected from the developer solvent 40a. Is returned to the liquid tank 111 and the developer tank 41 by dispersing a liquid (hereinafter, referred to as a reuse liquid) dispersed in the developer solvent 40a so as to have a concentration about the same as the toner concentration of the developer used for development. The recycling device 130 is configured. For this,
The recovery device 131 and the developer solvent 40 mixed with toner
a collection pipe 132 for collecting the purified liquid from the liquid tank 111 into the collection device 131;
The recycling device 130 is constituted by a liquid return pipe 133 for returning the liquid 11 to the liquid developer 11 and a developer return pipe 134 for supplying the recycled liquid to the developer tank 41. Also,
Although not shown, the collection pipe 132 is provided with an electromagnetic valve and a pump for generating a developing solution from the suction liquid tank 52 to the collection device.

When removing excess developer on the surface of the photosensitive drum 1 with the liquid suction device 5 having the above-described structure, the valve provided on the collection pipe 132 is closed to increase the confidentiality inside the liquid suction device 5. . Then, the suction pump 55 is operated in a state where air is sucked only from the gap G between the liquid suction member 51 and the surface of the photosensitive drum 1. At this time, the slit narrow groove 51a is filled with the developing solution solvent 40a as a flowing liquid, and the developing solution solvent 40a and the excess developing solution sucked from the photoreceptor cause the slit narrow groove 51a as shown in FIG. The upper portion of the groove 51a is closed by the photosensitive drum 1. Then, from the gap G between both walls of the slit narrow groove 51a and the photosensitive drum 1, air flows toward the slit narrow groove 51a as shown by arrows in the figure. When the amount of the developing solution solvent 40a sucked by the suction pump 53 is larger than the amount of the air flowing from the gap G, the slit narrow groove 51a is in a negative pressure state. From 112, the developing solution solvent 40a flows into the slit narrow groove 51a. Due to the negative pressure, the excess developer on the surface of the photosensitive drum 1, that is, the excess developer in the image area and the developer in the background area are sucked, and
Runs out of 3. At this time, the developer solvent 40a
Flows toward the end to which the suction pipe 53 is connected while washing away the toner on the background of the surface of the photosensitive drum 1 and flows out from the suction pipe 53. The sucked developer solvent mixed with the surplus developer, that is, the suction liquid, passes through the suction pipe 53 and is stored in the liquid tank 111.

Then, the suction liquid collected in the suction liquid tank 52 is supplied to the recycling device 130 at a predetermined timing at a predetermined timing, for example, the suction liquid tank 52.
A liquid level sensor (not shown) which detects the height of the developer surface in the suction liquid tank 52 attached to the suction liquid tank 52 when the developer surface reaches a predetermined height or every time a predetermined time elapses The liquid is separated into a purifying liquid and a reuse liquid and supplied to the liquid tank 111 and the developing liquid tank 41. In this case, the operation of the suction pump 55 is stopped, the valve is opened, and then the collection pump is operated. Then, the liquid tank 1 is stored in the collection pipe 132 by the operation of the collection pump.
The developing solution flows from 11 to the recovery device 131, and the suction solution, which is the developer solvent mixed with the toner, is recovered by the recovery device 131. Then, the recovery device 131 separates the toner mixed with the toner into a reuse liquid and a purification liquid. That is, the toner mixed in the developing solution solvent is collected by, for example, a so-called electrodeposition method of passing toner between the electrodes (not shown) to which a voltage is applied and attaching the toner to the electrodes, and developing the collected toner. It is dispersed in the liquid solvent 40a to make a reused liquid. The remaining liquid, that is, the developing solvent 40a from which the toner has been removed is used as the purifying liquid. Then, the recycled liquid is returned to the developer tank 41 by the developer return pipe 134, and is mixed with the developer in the developer tank 41 and used for the developing operation. Further, the purified liquid is returned to the liquid tank 111 by the liquid return pipe 133, and is used by the liquid suction device 5 as a flowing liquid. As described above, by removing the toner from the suction liquid and using it again for the developing operation, the toner can be effectively used, and the running cost can be reduced. In addition, since the reusable liquid obtained by dispersing the toner in a developer solvent to make the liquid approximately the same as the developer is supplied into the developer tank 41, the toner concentration in the developer tank 41 at the time of supplying the recycle liquid is increased. Can be kept constant. Further, since the toner is removed from the developer solvent mixed with the toner and used again as a flowing liquid and brought into contact with the surface of the photosensitive drum 1, a constant flushing effect can be always obtained.

Also in the liquid suction device 5 of the present embodiment, the removal performance is determined by the negative pressure generated in the slit 51a of the liquid suction device 5. And Embodiment 1
As in the case of (1), the removal performance is optimized by the suction pump 5
5 by adjusting at least one of the negative pressure generation capacity and the gap G. Therefore, unlike the case where a squeeze roller is used, even when the apparatus needs to be increased in size or increased in speed, the removal performance can be properly optimized without causing any trouble. In addition, since the removal performance can be enhanced by increasing the negative pressure generation capability, it is possible to sufficiently obtain the removal performance and form a good image by using a pump having an appropriate negative pressure generation capability. is there.

When the suction is performed while flowing the liquid through the narrow slits 51a of the liquid suction member 5 as in the liquid suction device 5 of the present embodiment, the air sucked from the gap G will It is considered that there are one that mixes as small bubbles into the air and one that repels outward while creating a turbulent flow at the boundary between the photoconductor and the liquid surface. On the other hand, unlike the liquid suction device 5 of the present embodiment, when suction is performed with the slit narrow groove without flowing the liquid, it is considered that most of the air sucked from the gap G is sucked from the slit narrow groove. Can be Therefore, as in the case of the liquid suction device 5 of the present embodiment, when performing suction while flowing the liquid through the slit narrow groove 51a of the liquid suction member 5, when performing suction with the slit narrow groove without flowing the liquid, In comparison, the amount of air sucked from the slit narrow groove 51a is reduced. Therefore, the noise generated in the slit narrow groove is smaller than when suction is performed in the slit narrow groove without flowing the liquid.

If a cleaning liquid, for example, a developing solution solvent is used as the flowing liquid as performed by the liquid suction device in the illustrated example, even if toner adheres to the background of the surface of the photosensitive drum 1, Can be washed away with a sink. At this time, since the electrostatic force acts on the toner in the image portion, that is, the toner image portion, the toner is not washed away. As a result, soiling can be prevented. This makes it possible to use a developing solution having a high toner concentration, thereby increasing the margin for setting the conditions of the toner concentration.

FIG. 4 is a view showing an example of a modification of the liquid suction member 51. As shown in FIG. The liquid suction member 51 has a predetermined convex portion on its surface that comes into contact with the photosensitive drum 1, and the convex portion comes into contact with the surface of the photosensitive drum 1 so that a slit flow path portion 511 as a developer sucking member is provided. A rotating member serving as a gap holding member for holding a gap between the photosensitive drum 1 and the photosensitive drum 1 is rotatably provided such that a surface facing the photosensitive drum 1 moves in the same direction as the photosensitive drum 1. Is adopted. Specifically, the liquid suction member 51 is attached to a slit flow path portion 511 provided with a slit narrow groove 51a similar to the liquid suction member 51 of FIG. And contact body covers 513a and 513b as storage means for storing the cylindrical rotary contact bodies 512a and 512b as the rotating members.

The rotary contact members 512a and 512b have metal shafts 514a and 514b at their respective axes, and are rotatably supported by the contact member covers 513a and 513b via the metal shafts 514a and 514b. I have.
At one end of each of the metal shafts 514a and 514b, a pulley 515 made of rubber or resin is provided.
a, 515b, and the pulleys 515a, 515b are provided.
The rotation of the motor 516 is transmitted to 15b via a gear (not shown).

The rotary contact members 512a and 512b are formed of rubber or resin elastic material, and the surface thereof is coated with a granular material or the rotary contact members 512a and
By kneading together with the material constituting 2b,
Irregularities of about 0 μm are formed. Then, the gap between the slit flow path portion 511 and the photosensitive drum 1 is maintained by the projection of the unevenness coming into contact with the surface of the photosensitive drum 1. At this time, the projection is formed in the slit narrow groove 51a. This blocks the flow path of the air flowing toward it. And
A portion other than the convex portion, that is, a gap formed between the concave portion of the unevenness and the surface of the photosensitive drum 1 faces the slit channel via the gap between the slit channel portion 511 and the photosensitive drum 1. The flow path of the flowing air is formed.

FIG. 5 is an explanatory view of the inside of the contact body cover 513a. The contact body cover 513b has the same configuration. The flow path of the air flowing toward the slit narrow groove 51a is formed between the photosensitive drum 1 and the rotating contact members 512a and 512.
If the suction pump is formed at a position other than the gap with the recess on the surface b, the amount of air flowing toward the slit narrow groove 51a increases, so that the suction pump cannot be downsized. Therefore,
In the contact body covers 513a and 513b accommodating the rotating contact bodies 512a and 512b, the rotating contact bodies 512a and 513b are provided.
The rotation contact body 5b does not hinder the rotation of the rotation contact body 512b.
A filling member 517 such as a foam is filled so that a sufficient airtightness can be maintained without generating an air flow path between the contact covers 12a and 512b and the contact body covers 513a and 513b. Thus, the flow path of the air flowing toward the slit narrow groove 51a is formed only in the gap between the photosensitive drum 1 and the concave portion on the surface of the rotary contact members 512a and 512b.

By the way, as described above, the liquid suction device 5
The removal performance of the surplus liquid due to is increased as the gap G between the photosensitive drum 1 and the liquid suction member 51 becomes smaller. Therefore, if the gap G is small, an appropriate removal performance can be obtained even with a small pump having a low negative pressure generation ability of the suction pump 55. However, if the liquid suction member 51 comes into close contact with the surface of the photosensitive drum 1 during liquid suction, the rotation of the photosensitive drum 1 becomes impossible. In the liquid suction member shown in FIG. 4, the gaps G are apparently reduced by the projections on the surfaces of the rotary contact members 512a and 512b contacting the photosensitive drum 1, and the projections keep the minute gaps stable, and The flow path 511 and the photosensitive drum 1 are not brought into close contact. This makes it possible to reduce the size of the pump, and
Stable surplus liquid removal performance can be obtained.

Further, the rotary contact bodies 512a, 512
b is provided so as to be rotatable so that the surface facing the photosensitive drum 1 moves in the same direction as the photosensitive drum 1, so that when the convex portion comes into contact with the toner image on the surface of the photosensitive drum 1 In this way, it is possible to prevent the toner image from being streaked, rubbing the toner image, and preventing the toner from accumulating on the protruding portions to generate streaky stains. Thereby, a good image without image degradation can be obtained. In addition, since the illustrated rotating contact bodies 512a and 512b are made of an elastic body, it is possible to absorb an impact when the convex portion comes into contact with the toner image. This allows
Damage to the toner image can be further prevented, and a good image can be obtained.

In the above embodiment, an example in which the collection device 131 is provided outside the liquid tank 111 has been described.
May be provided.

Further, in the above embodiment, the liquid suction device 5 is configured to remove the excess developer while circulating the flowing liquid between the liquid tank 111 and the liquid suction member 51. Although only the example has been described, a configuration in which a liquid supply unit that supplies a liquid to the liquid suction member 51 and a suction unit that suctions the liquid by the liquid suction member 51 is provided without performing liquid circulation is adopted. Is also good.

Further, a liquid replenishing device for replenishing the liquid flowing into the liquid tank 111 and a detecting device for detecting the amount of the developing solution in the liquid tank 111 are provided, and the shortage of the liquid is detected by the detecting device. The liquid replenishing device may be configured to replenish the flowing liquid.

Further, in this embodiment, only the example in which the rotating contact member as the gap holding member is arranged on the upstream and downstream sides of the slit narrow groove in the rotation direction of the photosensitive drum 1 has been described. In the case where the thickness of the developing solution on the body drum 1 is large and the developing solution is buried between the convex portions, the rotating contact member is provided on the photosensitive drum 1 in the rotation direction upstream of the narrow slits. Instead, it is desirable to provide it only on the downstream side.

[0044]

According to the first to fifth aspects of the present invention, the surplus developing solution on the surface of the latent image carrier after the development is removed by suction by the surplus liquid suction means. Then, since the excess liquid removing performance of the excess liquid suction means can be optimized by adjusting the suction force, unlike the case where a squeeze roller is used, even when the apparatus needs to be increased in size or increased in speed. In addition, there is an excellent effect that the above-described removal performance can be appropriately optimized without causing any trouble.

According to the second and fifth aspects of the present invention, the slit thin film is provided with a predetermined gap from the latent image carrier and has a length not less than the width of the image forming area on the surface of the latent image carrier. A groove is formed so as to face the image forming area, and a developer sucking member that sucks the excess developer from the slit narrow groove,
An excess developer on the surface of the latent image carrier using a liquid suction device having a negative pressure generating means for generating a negative pressure in the slit narrow groove in order to suck the excess developer with the developer suction member;
For example, since the surplus developing solution in the developer image portion and the developing solution in the background portion are removed, there is an excellent effect that the configuration is simple.

According to the third to fifth aspects of the present invention, the cleaning liquid is caused to flow through the narrow slit by the liquid suction device so that the surface of the cleaning liquid contacts the surface of the latent image carrier. In addition, since the excess developer is sucked, the amount of air sucked from the slit narrow groove is reduced as compared with the case where suction is performed in the slit narrow groove without flowing the liquid. Thereby, there is an excellent effect that the sound generated in the slit narrow groove is reduced as compared with the case where suction is performed in the slit narrow groove without flowing the liquid. Further, in the case where the cleaning liquid is caused to flow through the narrow slits, the developer adhering to the background on the surface of the latent image carrier is washed away with the cleaning liquid, so that there is an effect that background contamination can be prevented. . As a result, it is possible to use a developer having a high developer concentration, which has the effect of increasing the margin for setting the condition of the developer concentration.

According to the fourth and fifth aspects of the present invention, the developer mixed in the cleaning liquid is recovered by the recycling means by the recovery device provided in the developer circulation path and reused by the developing means. Therefore, there is an excellent effect that the developer is effectively used and the running cost is reduced. Further, by circulating the developer while collecting the developer mixed in the cleaning liquid by the recovery device in the developer circulation path, the cleaning performance of the background portion of the latent image carrier by the cleaning liquid is reduced. Therefore, there is an effect that a constant cleaning effect can be always obtained.

In particular, according to the fifth aspect of the present invention, the minute gap between the developer suction member and the latent image carrier is stably held by contacting the convex portion on the surface of the gap holding member. There is an excellent effect that can be. And, since the large number of projections on the surface of the gap holding member can reduce the flow rate of air flowing toward the slit narrow groove,
There is an excellent effect that the size of the pump can be reduced.
Further, since the surface of the gap holding member is movable in the same direction at a portion facing the surface of the latent image carrier, the convex portion comes into contact with the surface of the latent image carrier, and the convex portion contacts the surface of the latent image carrier. When the developer image is touched, it is possible to prevent the developer image from being scratched in a streak shape or from being rubbed. Therefore, there is an excellent effect that a good image can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of an electrophotographic copying machine according to an embodiment.

FIG. 2 is a perspective view showing a schematic configuration of an electrophotographic copying machine according to another embodiment.

FIG. 3A is a perspective view illustrating a schematic configuration of a liquid suction device of the copying machine. (B) is an explanatory view of the liquid suction by the liquid suction member of the liquid suction device.

FIG. 4 is a perspective view showing a modification of the liquid suction member of the liquid suction device.

FIG. 5 is an explanatory view of a rotary contact body of the liquid suction member.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 2 main charger 3 exposure device 4 wet developing device 40 developer 40 a developer solvent 41 developer tank 5 liquid suction device 51 liquid suction member 51 a slit narrow groove 52 suction liquid tank 53 suction pipe 55 suction pump 100 reuse Apparatus 101 Circulation pipe 102 Valve 103 Circulation pump 111 Liquid tank 112 Liquid supply pipe 130 Recycling device 131 Recovery device 132 Recovery pipe 133 Liquid return pipe 134 Developer return pipe 511 Slit flow path section 512a, 512b Rotary contact body 513a, 513b Contact Body cover 514a, 514b Metal shaft 517 Filling member 6 Transfer unit 7 Transfer 8 Cleaning device 9 Static elimination lamp

Claims (5)

[Claims] 1. A latent image carrier on which a latent image is formed, and a developer in which a developer is dispersed in a liquid carrier are carried on the surface, and the developer is supplied to the surface of the latent image carrier by rotation. Developing means for developing a latent image on the surface of the latent image carrier to form a developer image by supplying a developing solution to the surface of the latent image carrier by the developing roller; An excess liquid removing unit that removes a part of the liquid carrier attached to the latent image carrier, and a transfer unit that transfers a developer image on the surface of the latent image carrier from the latent image carrier to a transfer material. In the wet image forming apparatus having, as the excess liquid removing means, there is provided an excess liquid suction means for removing the excess developer on the surface of the latent image carrier after development with a width equal to or more than the image forming area width of the surface after development. A wet image forming apparatus. 2. A wet image forming apparatus according to claim 1, wherein said excess liquid suction means is provided with a predetermined gap from said latent image carrier, and is larger than an image forming area width of said latent image carrier surface. A slit fine groove having a length is formed so as to face the image forming area, and a developer sucking member for sucking the surplus developer from the slit narrow groove, and a surplus developer is sucked by the developer sucking member. A liquid suction device having a negative pressure generating means for generating a negative pressure in the slit narrow groove. 3. A wet image forming apparatus according to claim 1, wherein said excess liquid suction means is provided at a predetermined gap from said latent image carrier, and is larger than an image forming area width of said latent image carrier surface. A slit narrow groove having a length is formed so as to face the image forming area, and a developer or a cleaning liquid is flowed through the slit narrow groove so that the surface of the liquid contacts the surface of the latent image carrier. A developer suction member for sucking the excess developer; a liquid supply unit for supplying a developer or a cleaning solution to the slit narrow groove; and the developer suction member sucking the liquid and the excess developer. A liquid suction device having a negative pressure generating means for generating a negative pressure in the slit narrow groove for this purpose. 4. A wet-type apparatus according to claim 3, further comprising a liquid suction device for removing said surplus developer while circulating said cleaning liquid in a liquid circulation path including said developer suction member and said liquid supply means. In the image forming apparatus, there is provided a recovery device for recovering the developer from the cleaning liquid in the liquid circulation path, and a recycling unit for supplying the developer recovered by the recovery device to the developing unit for reuse. A wet image forming apparatus, comprising: 5. The wet image forming apparatus according to claim 2, wherein the surface of the latent image carrier forms an image while moving, the surface having a plurality of predetermined convex portions on the surface. The gap holding member that contacts the surface of the latent image carrier to hold the gap between the developer suction member and the latent image carrier moves in the same direction at a portion where the surface is opposed to the surface of the latent image carrier. A wet image forming apparatus provided so as to be capable of being used.