JPH08211746A - Liquid developing device - Google Patents

Abstract

PURPOSE: To obtain simple and compact constitution and to sufficiently clean a plate like developing electrode by sucking a liquid developer remaining on the surface of the developing electrode with a recovering pump through a slit. CONSTITUTION: The inside of the housing 49 of a liquid developing device 48Y is provided with the plate like developing electrode 62 disposed in a position facing the surface of a photoreceptor drum 42, a slit nozzle 66 for supplying the liquid developer to the gap 64 between the drum 42 and the electrode 62, a recovering roll 68 confronted with the drum 42 in a part nearer to the downstream side than the plate like developing electrode 62 and a scraping member 70 abutted on this roll. Then, a shutter 80 opened/closed by the on and off of a clutch is provided in the communicative part of a developer reservoir part 71 and the slit nozzle 66. further, a slit opening 72a is formed on the surface of the electrode 62 and the developer remaining on the surface of the electrode 62 is sucked/removed by the recovering pump connected to an opening 72b on one end of a slit groove 72.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an electrostatic latent image formed on the surface of an image carrier in an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer by using a liquid developer containing toner particles. The present invention relates to a liquid developing device that develops by developing.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using an electrophotographic system has been widely spread. In this electrophotographic image forming apparatus, a rotating image carrier (photoreceptor drum) normally formed in a drum shape is uniformly charged, and light carrying information of an image recorded on an original is exposed to the light. An electrostatic latent image is formed on the photosensitive drum by irradiating the body drum, and the electrostatic latent image is developed with a developer (toner), and the developed image is directly or via a transfer drum or the like on a sheet of paper. It is a device that obtains a printed (copy) image by transferring. The method of developing the electrostatic latent image is roughly classified into a dry developing method using a powder toner and a liquid developing method using a liquid developer containing toner particles. In the liquid developing method, a developing electrode which is arranged so as to face the surface of the image carrier and to which a bias voltage for developing is applied is usually used, and the liquid is formed in a gap between the surface of the developing electrode and the surface of the image carrier. It is a method of developing an electrostatic latent image by supplying a developer and causing the toner particles to electrophorese according to a developing electric field formed by the electrostatic latent image on the surface of the image carrier.

A variety of shapes and types of developing electrodes have been proposed as the developing electrodes used in the above liquid developing method, but as typical and practical ones, a roll-like developing electrode and a plate-like developing electrode are used. Can be mentioned. FIG. 6 shows an example of a liquid developing apparatus using a roll-shaped developing electrode. The liquid developing device 10 has an arrow mark 1 indicated by a rotation driving means (not shown).
Roll-shaped developing electrode 12 rotated in the direction indicated by 2a
And a scraping member 14 such as a scraper for cleaning the surface of the roll-shaped developing electrode 12 with its tip abutting, and a developer supply nozzle 16 for supplying a liquid developer to the roll-shaped developing electrode 12. ing. The roll-shaped developing electrode 12 is arranged at a distance of several hundreds of μm from the image carrier 18 which rotates in the direction indicated by the arrow 18a.
Further, the liquid developing device 10 is provided with a roll member 20 arranged on the downstream side of the image carrier 18 in the rotation direction, and a scraping member 22 whose front end abuts on the surface of the roll member 20. Rolls 24 that come into contact with the image carrier 18 and rotate freely are attached to both ends of the roll member 20 coaxially with the roll member 20. The roll member 20 is
The liquid developer, which is rotated in a direction indicated by an arrow 20a at a predetermined distance from the image carrier 18 and flows along the surface of the image carrier 18 after passing through the roll-shaped developing electrode 12, causes the roll member 20 to rotate. Is conveyed to the downstream side in the rotation direction of and is scraped by the scraping member 22. In the liquid developing device using such a roll-shaped developing electrode 12, the scraping member 14
As a result, the surface of the roll-shaped developing electrode 12 is cleaned so that a stable developed image can be obtained.

In the liquid development, as described above, the charged toner particles are electrophoresed according to the developing electric field formed by the electrostatic latent image formed on the surface of the image carrier to adhere to the electrostatic latent image. However, it has a drawback that the electrophoretic speed of the toner particles is slow and thus the developing speed is slow. In order to increase the developing speed, the developing nip (the developing electrode and the surface of the image carrier face each other, the liquid developer is supplied therebetween, and the liquid developer and the surface of the image carrier contact each other for development. The area 26 must be wide so that many toner particles can be electrophoresed and adhere to the electrostatic latent image in a short time. However, as shown in FIG. 6, the roll-shaped developing electrode 12 has a problem that the developing electrode has a roll shape, so that the developing nip 26 is narrow and it is difficult to increase the speed.

As a technique for solving the above-mentioned problems when using a roll-shaped developing electrode, one having a large roll diameter itself (see Japanese Patent Application Laid-Open No. 4-505222) or a plurality of roll electrodes on the surface of an image bearing member is used. It is proposed that the developing nip is widened as a whole by arranging it along the line (see Japanese Patent Application Laid-Open Nos. 62-264080 and 2-81070).

However, if the roll diameter itself is increased in order to increase the developing speed, or if a plurality of roll-shaped developing electrodes are arranged along the surface of the image carrier to widen the developing nip, the development There is a problem that the device becomes large. Furthermore, when a plurality of roll-shaped developing electrodes are used, a device for controlling the rotation of these is required, which complicates the developing device itself, leading to an increase in cost.

FIG. 7 shows an example of a liquid developing apparatus using a plate-shaped developing electrode instead of the roll-shaped developing electrode. Figure 7
Then, the same symbols are used for the same elements as in FIG. The liquid developing device 30 includes a fixed plate-shaped developing electrode 32, which is separated from the surface of the image carrier 18 by several hundreds of μm, and which faces the surface and extends in the width direction of the image carrier 18, and a plate-shaped developer electrode 3.
A developing solution supply slit 34 for supplying a developing solution is provided in a gap sandwiched between the surface of the image carrier 18 and the surface of the image carrier 18. Further, similar to the liquid developing device 10 of FIG. 6, a roll member 20, a scraping member 22 and the like are provided.

As shown in FIG. 7, in the liquid developing device 30 using the plate-like developing electrode 32, a plate-like developing electrode 34 having a smaller size than the roll-like developing electrode 12 (see FIG. 6) is used. Therefore, when the developing nip 26 having the same width as that of the liquid developing device 10 (see FIG. 6) provided with the roll-shaped developing electrode 12 is formed, the device can be significantly downsized.

However, as described above, the gap between the plate-shaped developing electrode 32 and the image carrier 18 is very small (several hundred μ).
Therefore, the liquid developer remains in this gap after the development, and the remaining liquid developer (residual meniscus) 36
When the toner is dried, the toner adheres to the developing electrode 34 and the image carrier 18, which may adversely affect the subsequent image formation. Especially when forming a color image,
There is a problem in that the residual meniscus 36 causes color mixing during image formation of secondary colors and thereafter, and the image quality is significantly impaired.
Further, as described above, the plate-shaped developing electrode 32 is fixed and the gap between the plate-shaped developing electrode 32 and the image carrier 18 is very small. Therefore, a cleaning member is inserted into this gap to remove the toner adhered to the plate-shaped developing electrode. Is difficult.

The following techniques have been proposed as techniques for solving the above problems when the plate-shaped developing electrode 32 is used. Regarding the removal of the residual meniscus 36 formed in the gap between the plate-shaped developing electrode 32 and the image carrier 18,
A technique for removing the residual meniscus by widening the gap between the surface of the plate-shaped developing electrode 32 and the surface of the image carrier 18 by making the liquid developing device 30 contactable and separable from the image carrier 18 (JP-A-62-165679). (See Japanese Patent Laid-Open Publication) or a technique for ejecting air into the gap between the plate-shaped developing electrode 32 and the image carrier 18 to blow away the residual meniscus 36 (Japanese Patent Laid-Open No. 3-18278).
No. 3, Japanese Patent Laid-Open No. 6-11942).

As a technique for cleaning the plate-shaped developing electrode 32, the plate-shaped developing electrode is separated from the image carrier and a cleaning member for scraping is brought into contact with the surface of the plate-shaped developing electrode 32 and slid. Technology (see Japanese Patent Laid-Open No. 3-72387), plate-shaped developing electrode 3
2 has a belt-shaped configuration and a roll-shaped developing electrode (see FIG. 6)
A technique of bringing a scraping member into contact with the plate to perform cleaning in the same manner as in (Japanese Patent Laid-Open No. 2-111983). After completion of development, a bias having the same polarity as the toner is applied to the plate-shaped developing electrode 32 to apply the bias to the plate-shaped developing electrode 32. A technique of electrically cleaning the plate-shaped developing electrode 32 by adhering the deposited toner to the image carrier 18 and removing the toner adhering to the image carrier 18 by a cleaning means after the transfer process (Japanese Patent Laid-Open No. 54-155045). No. gazette) is proposed.

[0012]

In the technique of removing the residual meniscus, the liquid developing device is constructed so that it can be brought into and out of contact with the image bearing member. Therefore, it is necessary to have a drive control means for contact and detachment. There is a problem that the developing device becomes complicated and large, which leads to an increase in cost. Further, the vibration generated when the liquid developing device is brought into contact with and separated from each other adversely affects the image quality, and when the liquid developing device is separated from the image carrier, a residual meniscus flows on the surface of the image carrier to disturb the developed image, There are problems such as generation of a flow pattern on the surface of the image carrier. Further, in the technique of ejecting air to blow off the residual meniscus, the inside of the apparatus may be contaminated by the scattering of the liquid developer. Further, since a nozzle and a compressor are required as an air jetting device, there is a problem that the liquid developing device is complicated and the cost is increased. In order to clean dirt on the plate-shaped developing electrode, in the technique of bringing the cleaning member for scraping into contact with the surface of the plate-shaped developing electrode and sliding the same, it is necessary to provide drive control means for the cleaning member for scraping. Similarly to the above, there is a problem that the developing device is complicated and the cost is increased. Moreover, as described above, since the gap between the plate-shaped developing electrode and the image carrier is usually as small as several hundreds of μm, the liquid developing device is used to bring the cleaning member into contact with the surface of the plate-shaped developing electrode and slide the cleaning member. Needs to be separated from the image carrier, and a driving means for separating must be provided.
There is a problem in that the developing device itself becomes complicated and large, which leads to an increase in cost.

In the technique of cleaning the plate-shaped developing electrode in the form of a belt and bringing the scraping member into contact with the plate-shaped developing electrode like the roll-shaped developing electrode,
Since a driving means for driving the belt-shaped plate-shaped developing electrode must be provided, the problems of complication of the developing device and increase in cost cannot be avoided. After completion of development, a bias having the same polarity as the toner is applied to the plate-shaped developing electrode, and the toner deposited on the surface of the electrode is attached to the surface of the image carrier to electrically clean the surface of the plate-shaped developing electrode.
In the technique for removing the toner attached to the image carrier 1 by the cleaning unit after the transfer process, it is necessary to provide a unit for preventing unnecessary toner attached to the surface of the image carrier from being transferred in the transfer device in the next process. Moreover, in cleaning, there is a problem that unnecessary toner must be cleaned at one time, which imposes a burden on the cleaning means, and since the toner removed by the cleaning means is discarded, the toner consumption increases and running High cost.

In view of the above circumstances, it is an object of the present invention to provide a liquid developing device which can be configured more simply and more compactly than the conventional one and can sufficiently clean the developing electrode.

[0015]

The first liquid developing apparatus of the present invention for achieving the above object forms an electrostatic latent image on a rotating image carrier, and forms the electrostatic latent image on a liquid developer. Bias voltage for development, which is disposed at a position where the surface is opposed to the surface of the image carrier and extends in the width direction of the image carrier, in an image forming apparatus that develops by using Is applied to the plate-shaped developing electrode, a developing solution supply means for supplying the liquid developer to a gap sandwiched between the surface of the plate-shaped developing electrode and the surface of the image carrier, In a liquid developing device provided with a recovery roll disposed at a position on the downstream side in the rotational direction of the image carrier to rotate along with the image carrier and recover the liquid developer flowing along the surface of the image carrier. , A table of the plate-shaped developing electrodes In addition, a slit-shaped opening extending in the longitudinal direction of the image bearing member is formed, and a slit having an opening formed in the other end and extending through the plate-shaped developing electrode, and an opening formed in the other end. A recovery pump that is connected to suck the liquid developer remaining in the gap is provided.

Here, the liquid developer is supplied during the time when the electrostatic latent image formed on the image carrier passes through the position facing the surface of the plate-like developing electrode, and after this time, the liquid developer is supplied. The developer supply control means for controlling the developer supply means so that the supply of the developer is stopped, and the liquid developer remaining on the plate-shaped developing electrode after the lapse of time is sucked through the slits. Thus, it is preferable to include a recovery pump control means for controlling the recovery pump.

Further, the second liquid developing apparatus of the present invention for achieving the above object uses the liquid developer which forms an electrostatic latent image on a rotating image carrier and contains toner particles. In an image forming apparatus for developing a latent image and transferring the developed image to a transfer material, a developing bias voltage is disposed at a position where the surface faces the surface of the image carrier and extends in the width direction of the image carrier. Is applied to the plate-like developing electrode, a developing solution supplying means for supplying the liquid developer to a gap sandwiched between the plate-like developing electrode and the surface of the image carrier, and the image more than the plate-like developing electrode. A collection roll to which a bias voltage is applied, which collects the liquid developer that is disposed along the image carrier at a position on the downstream side in the rotation direction of the carrier and rotates and flows along the surface of the image carrier, The plate-shaped developing electrode and In a liquid developing device equipped with a power supply for applying a bias voltage to the recovery roll, the electrostatic latent image formed on the image bearing member is passed through a position facing the surface of the plate-shaped developing electrode. A developer supply control means for controlling the developer supply means so as to supply the liquid developer to the gap and stop the supply of the liquid developer after the elapse of this time, and to the plate-shaped development electrode surface after the elapse of time. A cleaning bias voltage that directs the remaining toner particles in the liquid developer toward the surface of the image carrier is applied to the plate-shaped developing electrode, and the developed image formed on the image carrier is collected by the recovery roll. After passing through the position opposite to the cleaning roller, the toner particles in the liquid developer between the image carrier and the collecting roll are directed toward the collecting roll. Scan voltage are those, wherein characterized in that a bias control means for controlling the power to be applied to the collection roller.

[0018]

According to the first liquid developing apparatus of the present invention, since the liquid developer remaining on the surface of the plate-shaped developing electrode is sucked by the recovery pump through the slit, the liquid developer remaining on the surface of the plate-shaped developing electrode is sucked. The developer can be removed. Since the structure for removing the liquid developer remaining on the surface of the plate-shaped developing electrode is only the structure including the slit and the recovery pump connected to the slit,
It can be made smaller with a simpler configuration than before.

Here, the liquid developer is supplied during the time when the electrostatic latent image formed on the image carrier passes through the position facing the surface of the plate-shaped developing electrode, and after this time, the liquid A developer supply control means for controlling the developer supply means so as to stop the supply of the developer, and a suction means for sucking the liquid developer remaining on the plate-shaped developing electrode after the lapse of the time through the slit. By providing the recovery pump control means for controlling the recovery pump, the liquid developer remaining on the surface of the plate-shaped developing electrode can be promptly removed after the development is completed.

Further, according to the second liquid developing apparatus of the present invention, the bias control means applies the voltage to the plate-shaped developing electrode and the collecting roll in accordance with the position where the electrostatic latent image formed on the image carrier passes. By controlling the bias voltage to be applied, the toner in the liquid developer remaining on the surface of the plate-shaped developing electrode is once adhered to the image carrier, and the toner adhered to the image carrier is adhered to the recovery roll to be collected. Unwanted toner particles do not remain on the surface of the plate-shaped developing electrode and the surface of the image carrier. As described above, unnecessary toner is collected by the liquid developing device, and a means for avoiding unnecessary toner transfer in the transfer device in the next step is not required, so that the mechanism becomes complicated and the cost can be avoided.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid developing apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a color image forming apparatus 40 equipped with an embodiment of the liquid developing apparatus of the present invention. The color image forming apparatus 40 is provided with a photoconductor drum 42 that rotates in a direction indicated by an arrow 42 a, and the photoconductor drum 42 is provided on the outer periphery of the photoconductor drum 42.
Of a scorotron charger 44 for uniformly charging the surface of the photosensitive drum 42 and a laser ROS for forming an electrostatic latent image for each color separated image by irradiating the photoconductor drum 42 with a color separated optical image or an optical image corresponding to this. Raster Output Scann
er) 46 and liquid developing devices 48Y, 48M, 48C, 48 arranged near the photosensitive drum 42 and for developing the electrostatic latent image corresponding to each color separation image, along the rotational direction.
K, the transfer drum 50 that rotates in the direction indicated by the arrow 50a, on which the developed images of the respective colors of the photoconductor drum 42 are sequentially transferred and superimposed, and the cleaning device 52 that cleans the photoconductor drum 42 after the transfer. An erase lamp 54 is provided to remove the charge from the cleaned photosensitive drum 42. The color developed image transferred to the transfer drum 50 and superposed with the developed images of the respective colors is transferred electrically or mechanically to the recording paper 56 sandwiched between the transfer drum 50 and the roller 55, and is dried by a drying means (not shown). After being dried, a full-color image is formed on the recording paper 56.

Liquid developing devices 48Y, 48M, 48C, 4
A well-known liquid developer is used as the liquid developer contained in 8K. For example, toner particles composed of a pigment and an acrylic resin in a carrier liquid of a high resistance petroleum solvent (eg, Isopar manufactured by Esso Co.). A liquid developer containing a charge control agent that adjusts the polarity and charge amount of the toner particles, a dispersion stabilizer that promotes the dispersion of the toner particles and maintains the stability of the dispersion, and the like is used. As the photoconductor drum, one that has solvent resistance to the liquid developer used is used.
A photosensitive belt may be used instead of the photosensitive drum.

Referring to FIGS. 2 and 3, the liquid developing device 48
The configurations of Y, 48M, 48C and 48K will be described. The liquid developing devices 48Y, 48M, 48C, and 48K have the same configuration, and the liquid developing device 48Y will be described here. 2 is a plan view showing the liquid developing apparatus, and FIG.
2A is a schematic view, and FIG. 2B is a partially enlarged view of FIG.

Inside the housing 49 of the liquid developing device 48Y, a plate-shaped developing electrode 62 is disposed at a position where the surface thereof faces the surface of the photosensitive drum 42 and extends in the width direction of the photosensitive drum 42, and a plate. The slit nozzle 66 for supplying the liquid developer to the gap 64 (see FIG. 3A) sandwiched between the plate-shaped developing electrode 62 and the photosensitive drum 42, and the rotation of the photosensitive drum 42 more than the plate-shaped developing electrode 62. A collecting roll 68 facing the photosensitive drum 42 with a certain gap at a downstream side in the direction, and a scraping member 70 having a tip abutting the surface of the collecting roll 68 are provided. A developer reservoir 71 is also formed inside the housing 49, and an opening 71a formed in the developer reservoir 71 is connected to a developer supply pump 78 (see FIG. 4). In addition, the developer reservoir 71 and the slit nozzle 6
A shutter 80 that is opened and closed by turning on / off an external clutch (not shown) is provided in a portion where 6 communicates. A power source (not shown) for applying a bias voltage to the plate-shaped developing electrode 62 and the recovery roll 68 and a controller (not shown) for controlling this power source are provided outside the housing 49.
Is provided. The plate-shaped developing electrode 62 may have a flat plate shape, but if the plate-shaped developing electrode 62 has a shape having a curvature concentric with the surface of the photosensitive drum 42, the distance between the surface of the photosensitive drum 42 and the surface of the plate-shaped developing electrode 62 is constant. The development electric field becomes constant and the development efficiency increases. In addition, at both ends of the collecting roll 68, the photosensitive drum 42 and the collecting roll 6 are provided.
In order to stably form a minute gap with the tracking roller 8, a tracking roll member 69 that comes into contact with the surface of the photosensitive drum 42 and rotates freely is provided.

On the surface of the plate-shaped developing electrode 62, a slit opening 72a at one end of a slit groove 72 extending through the plate-shaped developing electrode 62 is formed. The width of the opening 72a is about several mm. The opening 72b at the other end of the slit groove 72 is provided with a recovery pump 76 via a control valve 74.
(See FIG. 4) and is connected to the plate-shaped developing electrode 6
The liquid developer remaining on the surface of No. 2 is sucked and removed by driving the recovery pump 76. When the opening 72a at one end of the slit groove 72 is formed at the lower surface portion of the plate-shaped developing electrode 62 where the liquid developer is likely to accumulate, the residual liquid developer can be more effectively sucked. If the width of the openings 72a and 72b of the slit groove 72 is too narrow, clogging may occur, and if the width is too wide, the suction force decreases and the remaining liquid developer cannot be sufficiently sucked. In the experiment, the most stable suction and removal effect was obtained when the opening width was about 1 mm.

Of the liquid developer supplied to the gap 64,
The liquid developer flowing toward the downstream side in the rotation direction of the photoconductor drum 42 along the surface of the photoconductor drum 42 is collected by the recovery roll 68 rotated in the direction indicated by an arrow 68a by a driving unit (not shown), and the liquid developer 42. And the recovery roll 68 is sheared and removed according to the speed difference between the recovery roll 68 and the recovery roll 68.
On the opening 49.
It is recovered by the recovery pump 76 (see FIG. 4) via a. The recovery roll 68 is cleaned by the scraping member 70.

FIG. 4 is a block diagram showing a circulation path of the liquid developer of the liquid developing apparatus of FIG. In the liquid developer circulation path, as shown in FIG. 4, a tank 82 for storing the liquid developer, a recovery pump 76 connected to the opening 72b and the opening 49a through a control valve 74, and a developer reservoir. A supply pump 78 for supplying the liquid developer to 71 is provided. There are two liquid developer recovery paths, one of which is the opening 49.
A path for collecting the developer inside the housing 49 via a, and the other one is the opening 7 of the slit groove 72 (see FIG. 3).
This is a path for sucking and collecting and removing the liquid developer remaining on the plate-shaped developing electrode 62 via 2b. The start / stop of suction of the recovery pump 76 is controlled by the control valve 74.

The liquid developer is supplied to the gap 64 sandwiched between the surface of the plate-shaped developing electrode 62 and the surface of the photosensitive drum 42 as follows. The liquid developer stored in the tank 82 is sent by the supply pump 78 to the developer reservoir 71 via the opening 71a. When the electrostatic latent image is not developed (non-developed), the shutter 80 is set to the position shown in FIG.
The liquid developer has moved to the position shown by the two-dot chain line in (b). Therefore, the liquid developer is recovered by the recovery pump 76 via the inside of the housing 49 and the opening 49a, and returns to the tank 82.
When the electrostatic latent image is developed, the shutter 80 moves to the position shown by the solid line in FIG. 3B, the liquid developer in the developer reservoir 71 is sent to the supply slit 66, and the gap 6 is formed.
4, the liquid developer is supplied. Although the liquid developer supply port is provided at one place, the liquid developer is once sent to the developer reservoir 71 and then supplied to the supply slit 66 so that the uniform gap 6 is formed.
4 is supplied. Further, as described above, the liquid developer is always circulated and accumulated in the developer reservoir 71 even during non-development, and the opening and closing of the shutter 80 allows the liquid developer to be supplied and stopped at high speed. it can. Since the liquid developer is constantly circulated, it is possible to prevent the developer from settling or aggregating.

Next, the timing of supplying the liquid developer to the gap 64 and the timing of sucking the liquid developer remaining on the plate-shaped developing electrode 62 will be described with reference to FIGS. FIG. 5 is a timing chart showing the timing of supplying the liquid developer when the electrostatic latent image is developed.

Before the image area of the photosensitive drum 42 on which the electrostatic latent image is formed (area on which the electrostatic latent image is formed) reaches the plate-shaped developing electrode 62 (before T1 in FIG. 5), A developing bias voltage is applied to the plate-like developing electrode 62 to develop the latent image. As the developing bias voltage, a potential between the non-exposed portion potential (charging potential) and the exposed portion potential is usually applied. A bias voltage outside the above range may be applied in consideration of the developing efficiency. Simultaneously with the application of the developing bias voltage to the plate-shaped developing electrode 62, a bias voltage equivalent to the developing bias voltage is also applied to the recovery roll 68 to develop the electrostatic latent image. Simultaneously with this application, the shutter 80 in FIG. 3B is moved from the position indicated by the chain double-dashed line to the position indicated by the solid line, and the liquid developer is supplied to the gap 64. A developing electric field is formed by the electrostatic latent image potential and the developing bias, and in accordance with the developing electric field, the toner particles in the liquid developer existing in the gap 64 are directed toward the photosensitive drum 42 in the image area toward the electrostatic latent image. In the non-image area in which the electrostatic latent image is not formed, the electrostatic latent image is electrophoresed toward the plate-shaped developing electrode 62 and toner particles adhere to the electrostatic latent image, so that the electrostatic latent image is developed.

The liquid developer is supplied for a period of time (T1 to T2 in FIG. 5) during which the electrostatic latent image formed on the photosensitive drum 42 passes through the position facing the surface of the plate-shaped developing electrode 62.
Until time), and after this time elapses,
The shutter 80 is moved to the position shown by the chain double-dashed line in (b), and the supply of the liquid developer to the gap 64 is stopped. When the supply of the liquid developer is stopped, the gap 64 and the gap 84
A residual meniscus 36 as shown in FIG. 7 is formed on both sides. The residual meniscus formed in the gap 64 is
It is sucked by the collection pump 76 (see FIG. 4) through the slit groove 72 for a predetermined time from the time T4 in FIG. The residual meniscus existing in the gap 84 adheres to the surface of the recovery roll 68 as the recovery roll 68 continues to rotate and is scraped off by the scraping member 70.

Further, after the time (time from T1 to T2 in FIG. 5) during which the electrostatic latent image formed on the photosensitive drum 42 passes through the position facing the surface of the plate-shaped developing electrode 62, Is applied to the plate-shaped developing electrode 62 with a bias voltage in which the toner particles in the residual meniscus formed in the gap 64 are directed toward the photosensitive drum 42. The electrostatic latent image formed on the photoconductor drum 42 is developed and collected by the recovery roll 68.
After passing through (after passing T3 in FIG. 5), a bias voltage in which the toner particles in the residual meniscus formed in the gap 84 are directed to the collecting roll 68 is applied to the collecting roll 68. As a result, when developing the electrostatic latent image, the toner particles deposited on the surface of the plate-shaped developing electrode 62 can be attached to the photosensitive drum 42 after the development, and the plate-shaped developing electrode 6
2 can be electrically cleaned, while the photoconductor drum 4
The toner particles attached to No. 2 are attached to the recovery roll 68, so that the photoconductor drum 42 can be electrically cleaned.

After the development, the residual meniscus formed in the gap between the plate-shaped developing electrode 62 and the photoconductor drum 42 is promptly removed so that color mixture can be prevented. Further, since the plate-shaped developing electrode 62 can always be used in a cleaned state, stable development can be obtained. In the color image forming apparatus provided with the liquid developing apparatus of the present invention, the developing apparatus can be downsized, and the color image forming apparatus can be downsized accordingly. Further, since the liquid developer is circulated and reused, the running cost can be reduced. Further, since the plate-shaped developing electrode is used in the liquid developing apparatus of the present invention, the development nip can be increased and the high-speed development can be performed even when the liquid developing device is downsized as compared with the case of using the roll-shaped developing electrode. Further, since the plate-shaped developing electrode can be cleaned without separating the developing device from the photoconductor drum, it is possible to prevent deterioration of image quality due to movement of the developing device.

[0034]

As described above, according to the first liquid developing apparatus of the present invention, the liquid developer remaining on the surface of the plate-shaped developing electrode is sucked by the recovery pump through the slit, so that the plate-shaped developing electrode is sucked. It is possible to sufficiently remove the residual toner on the developing electrode and prevent color mixing and developing electrode contamination due to this.

Further, according to the second liquid developing apparatus of the present invention, the bias voltage applied to the plate-shaped developing electrode and the collecting roll is set in accordance with the position where the electrostatic latent image formed on the image carrier passes. Since the toner particles are controlled and the unnecessary toner particles are attached to the recovery roll to be collected, the unnecessary toner particles do not adhere and remain on the surface of the plate-shaped developing electrode and the surface of the image carrier.

[Brief description of drawings]

FIG. 1 is a schematic view showing a color image forming apparatus provided with an embodiment of a liquid developing apparatus of the present invention.

FIG. 2 is a plan view showing an embodiment of the liquid developing apparatus of the present invention.

FIG. 3 is a schematic diagram showing the liquid developing device of FIG.
(B) is a partially enlarged view of (a).

FIG. 4 is a block diagram showing a circulation path of a liquid developer of the liquid developing apparatus of FIG.

FIG. 5 is a timing chart showing the timing of supplying a liquid developer when an electrostatic latent image is developed.

FIG. 6 is a schematic view showing a conventional liquid developing device using a roll-shaped developing electrode.

FIG. 7 is a schematic view showing a conventional liquid developing device using a plate-shaped developing electrode.

[Explanation of symbols]

 40 Color Image Forming Device 42 Photosensitive Drum 48Y, 48M, 48C, 48K Liquid Developing Device 56 Recording Paper 62 Plate-like Developing Electrode 64 Gap 68 Recovery Roll 72 Slit Grooves 72a, 72b Opening 76 Recovery Pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyohiro Shigehiro 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Uchinabina Business Office (72) Inventor Satoshi Usui 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd. Ebina Business Office (72) Inventor Shin Arakura 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.In Ubina Business Office (72) Inventor Akihiro Ida 2274 Hongo, Ebina City, Kanagawa Fuji Xerox Co., Ltd.

Claims (3)

[Claims] 1. An image forming apparatus for forming an electrostatic latent image on a rotating image carrier, developing the electrostatic latent image with a liquid developer, and transferring the developed image to a transfer material. A plate-shaped developing electrode, which is disposed at a position facing the body surface and extends in the width direction of the image carrier, to which a developing bias voltage is applied, the plate-shaped developing electrode surface, and the image carrier surface. And a developing solution supplying means for supplying the liquid developer to a gap sandwiched between the plate-shaped developing electrode and the plate-shaped developing electrode, the position being downstream of the plate-shaped developing electrode in the rotational direction of the image carrier and being arranged along the image carrier. In a liquid developing device including a collecting roll that collects the liquid developer flowing along the surface of the image carrier, a slit-shaped opening extending in the longitudinal direction of the image carrier is formed on the surface of the plate-shaped developing electrode. Is formed with the plate A slit that extends through the developing electrode and has an opening formed at the other end, and a recovery pump connected to the opening formed at the other end for sucking the liquid developer remaining in the gap are provided. And a liquid developing device. 2. The liquid developer is supplied during the time when the electrostatic latent image formed on the image bearing member passes through a position facing the surface of the plate-shaped developing electrode, and the liquid developing agent is supplied after the time has elapsed. A developer supply control means for controlling the developer supply means so that the supply of the developer is stopped, and the liquid developer remaining on the plate-shaped developing electrode after the lapse of time is sucked through the slits. 2. The liquid developing apparatus according to claim 1, further comprising recovery pump control means for controlling the recovery pump. 3. An image forming apparatus for forming an electrostatic latent image on a rotating image carrier, developing the electrostatic latent image using a liquid developer containing toner particles, and transferring the developed image to a transfer material.
A plate-shaped developing electrode to which a bias voltage for development is applied, the plate-shaped developing electrode disposed at a position facing the surface of the image carrier and extending in the width direction of the image carrier, and the plate-shaped developer electrode and the image. A developer supply unit that supplies the liquid developer to a gap sandwiched between the surface of the carrier and a position downstream of the plate-shaped developing electrode in the rotational direction of the image carrier so as to follow the image carrier. A collection roll to which a bias voltage is applied, which collects the liquid developer that is arranged and rotated, and flows along the surface of the image carrier, and a power supply that applies a bias voltage to the plate-shaped developing electrode and the collection roll. In a liquid developing device provided with the liquid developer, the liquid developer is supplied to the gap during the time when the electrostatic latent image formed on the image carrier passes through a position facing the surface of the plate-shaped developing electrode, and the time elapses. later A developing solution supply control means for controlling the developing solution supply means so as to stop the supply of the liquid developer, and the toner particles in the liquid developing solution remaining on the surface of the plate-shaped developing electrode after the lapse of time. A cleaning bias voltage that directs the surface of the image carrier is applied to the plate-shaped developing electrode, and the developed image formed on the image carrier passes through a position facing the recovery roll, and then the image carrier is formed. A bias control means for controlling the power supply so that a cleaning bias voltage for directing the toner particles in the liquid developer between the body and the recovery roll to the recovery roll is applied. And a liquid developing device.