JPH1063105A - Wet image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the wasteful consumption of developer caused by the drying of isoper on an image carrier. SOLUTION: As soon as the trailing edge of a latent image on a photoreceptor 1 in a final copying stage, which is formed by a latent image forming device 20, passes through the developing roller 31 of a developing device 30 for developing the latent image to be a toner image, the supply of the developer to the device 30 is stopped. As soon as the trailing edge of residual toner on the photoreceptor 1 after transferring the toner image to transfer paper passes through the cleaning blade 52 of a cleaning device 50 for removing the residual toner, the blade 52 and a cleaning roller 51 are separated from 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, a printer, etc. of an electrophotographic system for performing wet development using a liquid developer.

[0002]

2. Description of the Related Art A liquid developer (developer) of a wet image forming apparatus generally uses a highly volatile isoper as a solvent for the toner. For this reason, in this wet image forming apparatus, there is a disadvantage that the developer is wastefully consumed by natural drying (evaporation) of the isoper when it is not operating.

Conventionally, the following techniques have been proposed in order to suppress such wasteful consumption of the developer. An evaporation-preventing member, which is lighter than the specific gravity of the developer, is densely floated on the surface of the developer, and a coating layer made of an oil-repellent material is formed on the surface of the evaporation-prevention member. (“Evaporation prevention member in developer storage tank” described in JP-A-3-144596). By providing a shutter that seals the opening around the toner carrier (development sleeve) during non-development, the solvent of the liquid toner is prevented from evaporating during non-development (see “Liquid Liquid” described in JP-A-4-83282). Developing device ”). By forming an area where the developer can stay in the photoreceptor, the developing roller and the squeeze roller, and limiting the area where the developer is present in the developing device casing to approximately this area, the amount of the developing solution volatilized in the developer is reduced. And the amount of developer circulation is reduced ("Liquid coating device and wet developing device" described in JP-A-7-199668).

[0004]

By the way, in this type of wet image forming apparatus, the latent image formed on the image carrier (photoreceptor) is imaged by a developing member (developing roller) of the developing device. The developer is developed by adhering a developing solution on the carrier, but since the developing solution on the image carrier is in the form of a thin film that is easy to dry, its isopers dry very quickly.

[0005] Therefore, when the copying amount per day is large, the non-operation time of the apparatus is short and the amount of drying of the isoper on the image carrier is small, but the copying amount per day is small. Since the non-operating time of the apparatus is long, the next copying process is started after the isoper on the image carrier after the final copy is completely dried.

Therefore, in a conventional wet image forming apparatus,
Due to the drying of isopers on the image carrier as described above,
There was a problem that the developer was wasted.

[0007]

According to the present invention, the supply of the developing solution to the image carrier after the trailing edge of the latent image in the final copying process is stopped, and the image carrier after the trailing edge of the residual toner is stopped. The pressing of the cleaning member on the upper side is released. in this way,
By stopping the supply of the developer onto the image carrier after the trailing end of the latent image in the final copying process, excess developer on the image carrier causing wasteful consumption of the developer is stopped. Is removed, and the pressure contact of the cleaning member on the image carrier after the rear end of the residual toner is released, so that the image carrier having no developer adhering and the cleaning member contact with the image carrier. Damage is avoided.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a wet image forming apparatus according to the present invention,
At the same time that the trailing end of the latent image on the image carrier in the final copying process formed by the latent image forming device passes through the developing member of the developing device for forming the latent image into a toner image, The supply of the developing solution is stopped, and the rear end of the residual toner on the image carrier after the transfer of the toner image to the transfer target body is performed by the image carrier of the cleaning device for removing the residual toner. The cleaning member is separated from the image carrier at the same time when the cleaning member passes through the cleaning member which can be freely attached to and separated from the image carrier.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. First, a general configuration of a wet image forming apparatus according to the present invention will be described. FIG. 2 shows a configuration in the vicinity of an image carrier of an electrophotographic copying machine in a wet development system.

As is well known, this wet type electrophotographic copying machine has a photosensitive member 1 as an image carrier, a corona discharger 2 for charging an image forming area on the photosensitive member 1, and a part other than the image forming area. A latent image forming apparatus 20 including an eraser 3 for removing charges on the photoconductor 1 and an exposing device 10 for exposing a charged latent image forming area on the photoconductor 1 to form a latent image; A developing device 30 having developing rollers 31 and 32 as developing members for converting a latent image formed on the photoreceptor 1 with a developing solution described later into a toner image (visualization);
A registration roller 41 that feeds a transfer sheet P as a transfer object conveyed from a sheet feeding unit (not shown) to the photosensitive member 1 in accordance with a movement timing of a toner image formed on the photosensitive member 1;
Transfer charger 4 for transferring a toner image to transfer paper P
2, a transfer device 40 having a separation roller 43 for separating the transfer paper P after the transfer of the toner image from the photoreceptor 1 and a turn belt 44, and on the photoreceptor 1 after the transfer of the toner image onto the transfer paper P A cleaning device 50 having a cleaning roller 51 and a cleaning blade 52 as a cleaning member for removing residual toner; a static elimination lamp 53 for removing residual charges on the photoconductor 1 after cleaning; a developing device 30 and cleaning Developer storage device 200 for supplying developer to device 50 (FIG. 3)
And

In FIG. 2, a photoreceptor 1 is uniformly charged to, for example, a positive polarity by a corona discharger 2 as a charger.
At the same time, the charges other than those in the image forming area are removed by the eraser 3. Next, the original set on the contact glass of the apparatus main body is irradiated with a scanning illumination lamp, and the reflected light from the original is irradiated onto the photoreceptor 1 by an exposing device 10 including a scanning mirror, a lens, and a reflecting mirror (not shown). The exposure forms an electrostatic latent image of the document on the image forming area of the photoconductor 1.

The latent image formed on the photoreceptor 1 is divided into two developing rollers 31 and 32 which are a developer carrier of the developing device 30.
Thus, for example, a developer containing negatively charged toner is supplied to the latent image to form a toner image. Here, excess developing solution supplied onto the photoconductor 1 by the developing rollers 31 and 32 is removed by a reverse roller 33 that rotates in a direction opposite to the rotation direction of the photoconductor 1.

Next, the transfer paper P, which is conveyed from the paper feed unit and is waiting at the nip of the registration roller 41, is transferred to the photosensitive member 1 with the timing of the leading edge of the toner image by the rotation of the registration roller 41. The sheet is conveyed toward a transfer section between the charger 42.

The transfer paper P conveyed to the transfer section is transferred to the toner image on the photoreceptor 1 by the transfer charger 42 applying a charge having a polarity opposite to that of the toner to the back surface thereof. The transfer paper P on which the toner image has been transferred is separated from the photoreceptor 1 by the separation roller 43 and the turn belt 44, and then the toner image is fixed by a fixing device (not shown), and is discharged out of the apparatus as a hard copy.

On the other hand, the residual toner remaining on the photoconductor 1 without being transferred to the transfer paper P in the transfer section is removed from the photoconductor 1 by the cleaning roller 51 and the cleaning blade 52 of the cleaning device 50. The photoreceptor 1 whose surface has been cleaned by the cleaning device 50
In addition, the residual charge on the surface is further neutralized by light irradiation of the neutralization lamp 53 to prepare for the next image formation.

As shown in FIG. 3, this wet electrophotographic copying machine has a liquid supply pump (not shown) and a developer tank 201.
The developing solution in the developing solution tank 201 is supplied to the developing device 30 and the cleaning device 50 through the liquid supply tubes 250a and 260a by the operation of the liquid supply pump. It is configured as follows. Developing device 30 and cleaning device 5
The surplus developer supplied to the developing tank 201 is collected into the developer tank 201 through the development recovery port 250b and the cleaning recovery tube 260b.

As shown in FIGS. 4 and 5, when the solenoid 59 is turned on, the cleaning roller 51 and the cleaning blade 52 of the cleaning device 50 of the wet electrophotographic copying machine come into contact with the photosensitive member 1. When the solenoid 59 is turned off, the cleaning roller 51 and the cleaning blade 52 are separated from the photoreceptor 1 by the elasticity of a spring (not shown).

FIG. 6 shows the operation timing of the main part of the conventional wet electrophotographic copying machine. In FIG. 6, when the operator presses a print button (not shown), a main motor (not shown) rotates. In conjunction with this, the supply pump of the developer storage device 200 is started, and the developer tank 20 is started.
1 is the developing device 30 and the cleaning device 5
0, and a predetermined copying process is performed as described above. When the final copy process is completed and the transfer paper P is discharged out of the machine, the main motor is stopped, and the liquid supply pump is stopped in synchronism therewith, so that the developer tank 2 is stopped.
The supply of the developer from 01 is stopped. Further, in this conventional wet-type electrophotographic copying machine, the solenoid 59 is configured to contact and separate from the photoconductor 1 in synchronization with turning on / off of a power switch (not shown).

Therefore, in this conventional wet electrophotographic copying machine, when the main motor is stopped, the cleaning blade 5 in the rotating direction (clockwise) of the photosensitive member 1 in FIG.
2 to the developing roller 31 in the range of about 90 °
No developer is attached on the top, but about 270
The developing solution having a film thickness of about 50 μm on average is always adhered on the photosensitive member 1 in the range of °.

For this reason, in a conventional wet electrophotographic copying machine, for example, when the drum diameter of the photosensitive member 1 is 80 mm and the drum length is 300 mm, about 2.8 cc (3/4 ×)
8π × 0.005 × 30 = 2.8) developer solution
This means that it always adheres to the top.

Approximately 2.8c adhering on the photoreceptor 1
The amount of developer c corresponds to the amount of developer consumed for 20 A4 size transfer papers because the amount of developer consumption per A4 size transfer paper is about 0.14 cc. Therefore, when about 2.8 cc of the developer adhering to the photoreceptor 1 is naturally dried, the developer is consumed extremely wastefully.

For this reason, in the conventional wet type electrophotographic copying machine, the relationship between the amount of copy per month and the number of usable copies of 2 liters of developer in the supply bottle is as shown in FIG. When the copy amount is less than 1000 sheets,
There is a problem that the developer in the replenishing bottle is emptied even though few copies are taken.

Therefore, in the wet image forming apparatus of the present invention,
As shown in FIG. 1, a rear end of the latent image on the photoreceptor 1 as an image carrier in a final copying process formed by the latent image forming device 20 is a developing device for converting the latent image into a toner image. 30 and at the same time as passing through the developing roller 31 as a developing member
The supply of the developing solution to the developing device 30 is stopped, and the rear end of the residual toner on the photoreceptor 1 after the transfer of the toner image onto the transfer paper P as the transfer receiving body is cleaned to remove the residual toner. The cleaning blade 52 and the cleaning roller 51 are separated from the photoconductor 1 at the same time when the cleaning blade 52 as a cleaning member of the apparatus 50 is passed.

As described above, the supply of the developing solution to the photosensitive member 1 after the trailing end of the latent image in the final copying process is stopped, so that the developing solution is unnecessarily consumed. Is removed, and the pressure contact of the cleaning roller 51 and the cleaning blade 52 on the photosensitive member 1 after the trailing end of the residual toner is released.
Damage to the photoconductor 1 due to contact between the photoconductor 1 having no developer and the cleaning roller 51 and the cleaning blade 52 can be avoided.

[0025]

According to the present invention, the supply of the developing solution to the image carrier after the trailing end of the latent image in the final copying step is stopped, thereby causing wasteful consumption of the developing solution. An unnecessary developing solution can be prevented from adhering to the image carrier, and the pressure-free contact of the cleaning member on the image carrier after the trailing end of the residual toner can be eliminated, so that the image without the developing solution adheres. Damage to the image carrier due to contact between the carrier and the cleaning member can be avoided.

[Brief description of the drawings]

FIG. 1 is a timing chart showing operation timings of main parts in a wet image forming apparatus according to the present invention.

FIG. 2 is a configuration diagram of the vicinity of a photoconductor of an electrophotographic copying machine in a wet development system for describing a general configuration of a wet image forming apparatus in which the present invention is implemented.

FIG. 3 is a perspective view showing a developer storage device of the electrophotographic copying machine in the wet developing system.

FIG. 4 is a perspective view showing a cleaning device of the electrophotographic copying machine in the wet developing system.

FIG. 5 is a cross-sectional view of the cleaning device of the electrophotographic copying machine in the wet developing system as viewed from the rear of the copying machine.

FIG. 6 is a timing chart showing operation timings of main parts of an electrophotographic copying machine in a conventional wet development system.

FIG. 7 is a graph showing the relationship between the amount of copy per month of an electrophotographic copying machine in a conventional wet development system and the number of usable copies of a 2 liter developer in a replenishing bottle.

[Explanation of symbols]

 Reference Signs List 1 photoconductor 20 latent image forming device 30 developing device 31, 32 developing roller 40 transfer device 50 cleaning device 51 cleaning roller 52 cleaning blade 59 solenoid 200 developer storage device 201 developer tank 250a, 260a supply tube 250b development recovery port 260b Cleaning collection tube

Claims (1)

[Claims] An image carrier, a latent image forming apparatus for forming a latent image on the image carrier, a developing device having a developing member for converting the latent image into a toner image, and a transfer object A transfer device for transferring the toner image to the image carrier, and a transfer device for removing the residual toner on the image carrier after transferring the toner image to the transfer-receiving member. A latent image on the image carrier in a final copying process in a wet image forming apparatus including a cleaning device having a simple cleaning member and a developing device and a developer storage device for supplying a developing solution to the cleaning device. At the same time as the end passes through the developing member, the supply of the developer to the developing device is stopped, and at the same time as the trailing end of the residual toner on the image carrier passes through the cleaning member, the cleaning member is removed from the image carrier. Image formation characterized by being separated from the surface Location.