JP2000181232A - Wet type developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a printing defect (stripe or the like) or the like caused by the defective scraping of a scraping part or the like. SOLUTION: This wet type developing device is provided with a developing part 10 developing an electrostatic latent image formed on an image carrier 1 with liquid developer and the scraping part 30 having a squeegee roller 31 for scraping the excessive developer by coming in contact with the carrier 1. The scraping part 30 is provided with the roller 31 scraping the excessive developer on the carrier 1, a washing tank 32 in which carrier liquid C used for washing the surface of the roller 31 by the circulation current of the liquid is put, a doctor 33 scraping the liquid C attached to the roller 31 and a circulation pump 34 circulating the liquid C in the tank 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a wet developing apparatus used for wet electrophotographic printing using a liquid developer.

[0002]

2. Description of the Related Art FIG. 4 is a schematic view showing an example of a conventional wet developing device. A conventional wet developing device contacts a liquid developer T in which toner particles are dispersed in an insulating carrier liquid with an image carrier 1 on which an electrostatic latent image is formed, and removes the toner particles in the liquid developer T. A developing unit 10 attached to the electrostatic latent image for visualization, and after the developing unit 10, a surplus developer adhering to the image carrier 1 is removed, and a ground formed by toner particles contained in the surplus developer Scraping unit 20 to prevent dirt
And had.

A developing section 10 includes a developing roller 11 made of a conductive material in a developing solution tank 12 filled with a liquid developer T.
Are arranged close to the image carrier (organic photoreceptor or the like) 1 with a small gap.

[0006] By rotating the developing roller 11, the liquid developer T supplied by a toner supply unit (not shown) (not shown) is pumped into the developer tank 12, and a charging device (not shown) is charged on the image carrier 1. Contact with the electrostatic latent image formed by the exposure means. At this time, the developing speed is improved by applying a developing bias voltage to the developing roller 11 by a voltage supply unit (not shown).

After the contact, the doctor blade 13
The developer remaining on the developing roller 11 is removed (history is eliminated).

The scraping section 20 has a squeegee roller 21 made of a conductive material disposed close to the image carrier 1 with a small gap.

By rotating the squeegee roller 21, the liquid is drained by utilizing the viscosity of the liquid. At this time, applying a bias voltage equivalent to the developing bias voltage to the squeegee roller 21 assists development of a portion where development is not sufficiently performed, and electrically attracts toner particles in excess developer. Thus, it is possible to further prevent soiling.

Further, after the surplus developer is scraped off, the surplus developer adhered on the squeegee roller 21 is removed (elimination of history) by the doctor blade 23.

[0009]

However, in the conventional wet developing apparatus described above, foreign matters (dust, dust, etc.) adhere to the surface of the squeegee roller 21 particularly during long-time continuous operation or re-operation after the apparatus is stopped. Adhesion of garbage) and doctor blade 2
3, the squeegee roller 21
And a small gap is generated between the doctor blade 23 and
Normal scraping (history elimination) by the doctor blade 23 is no longer performed, and toner particles may be streaked on the squeegee roller 21 in some cases.

When the excess developer on the image carrier 1 is scraped off with the toner accumulated on the squeegee roller 21, the gap between the image carrier 1 and the squeegee roller 21 at the toner adhering portion (FIG. That is, since the electric field intensity fluctuates, the amount of toner particles adhering to the developer fluctuates, and as a result, there is a problem that streaks (development unevenness) occur in the printing direction.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a wet developing device capable of preventing a printing defect (a streak or the like) caused by a defective scraping of a squeegee portion or the like.

[0012]

According to a first aspect of the present invention, there is provided a developing unit (10) for developing an electrostatic latent image formed on an image carrier with a liquid developer. A scraping means (30) having a squeegee section for scraping excess developer in contact with the image carrier, wherein the scraping means cleans the squeegee section (31) with a cleaning liquid (30). C) Cleaning unit (3)
4, 35, 36).

According to a second aspect of the present invention, in the wet developing device according to the first aspect, the scraping means is a doctor unit (3) for scraping the washing liquid after washing in the washing unit.
(3) A wet developing apparatus comprising:

[0014] The invention of claim 3 is claim 1 or claim 2.
3. The wet developing device according to claim 1, wherein the cleaning section (34).
Is a cleaning device for circulating the cleaning liquid through the squeegee section for cleaning.

[0015] The invention of claim 4 is the invention of claim 1 or claim 2.
3. The wet developing device according to claim 1, wherein the cleaning section (35).
Is a wet type developing device, wherein air is blown in the cleaning liquid to the squeegee portion for cleaning.

The invention according to claim 5 is the invention according to claim 1 or 2.
3. The wet developing device according to claim 1, wherein the cleaning unit (36)
The present invention relates to a wet developing apparatus, wherein the cleaning is performed by a brush that comes into contact with the squeegee section in the cleaning liquid.

The invention according to claim 6 is the invention according to claims 1 to 5.
In the wet developing device according to any one of the above, the developing unit uses a liquid developer (T) in which toner particles are dispersed in a carrier liquid, and the cleaning unit uses the liquid developer as the cleaning liquid. Using a carrier liquid (C),
Is a wet developing device.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described in more detail.
FIG. 1 is a schematic view showing an embodiment of a wet developing device according to the present invention. In addition, parts that perform the same functions as those of the above-described conventional example are denoted by the same reference numerals or unified reference numerals at the end, and redundant description will be omitted as appropriate. In the wet developing device of this embodiment, the developing unit 10 is the same as the conventional one, but the scraping unit 30 is improved as follows.

That is, the scraping section 30 includes a squeegee roller 31 for scraping excess developer on the image carrier 1 and a cleaning liquid containing a carrier liquid C for cleaning the surface of the squeegee roller 31 by a liquid circulation flow. A tank 32 and a doctor 3 for scraping the carrier liquid C adhered to the squeegee roller 31
3 and a circulation pump 34 for circulating the carrier liquid C in the washing tank 32.

Next, the operation of the wet developing apparatus according to the present embodiment will be described. First, an electrostatic latent image formed on the image carrier (organic photoreceptor or the like) 1 is charged into a developer tank 12 by a not-shown toner supply unit (pump or the like) by a charging / exposure unit (not shown). The supplied liquid developer T is brought into contact with the developing roller 11. At this time, a developing bias voltage is applied to the developing roller 11 by a voltage supply unit (not shown) to improve the developing speed.

Next, the electrostatic latent image developed by the liquid developer T enters the scraping section 30 and is provided with a squeegee roller 31.
As a result, surplus developer is removed. At this time, a bias voltage equivalent to the developing bias voltage is applied to the squeegee roller 31 to improve the squeegee ability.

The squeegee roller 31 having the surplus developer (possibly foreign matter) adhered to the surface enters the cleaning tank 32 in which the carrier liquid C is circulated, and is cleaned by the circulating flow of the carrier liquid C in the tank. Is done.

After passing through the cleaning tank 32, the carrier liquid C adhering to the squeegee roller 31 is removed by the doctor blade 33, and the surface of the squeegee roller 31 is returned to a squeegeeable state.

As described above, according to this embodiment, after the excess developer on the image carrier 1 is scraped off by the squeegee roller 31, the surface of the squeegee roller 31 is washed with the carrier liquid C, and the adhered carrier is removed. Since the liquid is scraped off by the doctor 33, it is possible to prevent poor scraping of the surface of the squeegee roller 31 (defective history resolution).

(Other Embodiments) Without being limited to the embodiments described above, various modifications and changes are possible, and these are also within the equivalent scope of the present invention. For example, the developing device according to the present invention is to eliminate doctor failure by cleaning the squeegee roller after removing excess developer and then applying a doctor blade, and the cleaning unit of the squeegee roller is as described above. However, the present invention is not limited to this.

That is, the cleaning section of the squeegee roller is not limited to the example in which the squeegee roller is passed through the circulating flow of the carrier liquid. As shown in FIG.
Air may be blown. Further, as shown in FIG.
A brush 36 or the like that comes into contact with the device may be provided. In addition to this, although not shown, an ultrasonic vibrator or the like is used.
The carrier liquid C may be washed by applying vibration.

The cleaning section can be considered to be used to further enhance the function of the doctor blade 33. However, if the cleaning section alone is sufficient, the doctor blade 33 can be omitted.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An OPP using the wet developing apparatus shown in FIGS.
Electrostatic printing was performed on the film. In the conventional developing device shown in FIG. 4, quality defects (streaks in the printing direction) due to poor scraping of the surface of the squeegee roller 21 particularly occur during continuous movement or during restart after the device is stopped. On the other hand, in the case where the developing device of the present embodiment of FIG. 1 is used, even during continuous printing, the surface of the squeegee roller 31 is scraped off satisfactorily, and the above-described deterioration in print quality can be prevented. did it.

[0029]

As described above in detail, according to the present invention, after the surplus developer on the image carrier is scraped off by the squeegee section, the surface of the squeegee section is washed with a cleaning liquid to thereby remove the squeegee section. This has the effect of preventing printing defects and the like caused by poor surface scraping.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a wet developing device according to the present invention.

FIG. 2 is a schematic view showing another embodiment of the wet developing device according to the present invention.

FIG. 3 is a schematic view showing still another embodiment of the wet developing apparatus according to the present invention.

FIG. 4 is a schematic view showing an example of a conventional wet developing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image carrier 10 developing unit 11 developing roller 12 developer tank 13 doctor blade T liquid developer 20 scraping unit 21 squeegee roller 22 tray 23 doctor blade 30 scraping unit 31 squeegee roller 32 tray 33 doctor blade 34 circulation pump 35 air pump 36 brush C carrier liquid

Claims (6)

[Claims] A developing unit for developing an electrostatic latent image formed on the image carrier with a liquid developer; and a squeegee unit having a squeegee unit for scraping an excess developer by contacting the image carrier. And a cleaning unit for cleaning the squeegee unit with a cleaning liquid. 2. The wet developing apparatus according to claim 1, wherein said scraping means includes a doctor unit for scraping off the cleaning liquid after cleaning by said cleaning unit. 3. The wet developing device according to claim 1, wherein the cleaning unit performs cleaning by circulating the cleaning liquid through the squeegee unit. 4. The wet developing device according to claim 1, wherein the cleaning unit cleans the squeegee unit by blowing air in the cleaning liquid. 5. The wet developing device according to claim 1, wherein the cleaning unit performs cleaning with a brush that comes into contact with the squeegee unit in the cleaning liquid. 6. Any one of claims 1 to 5
In the wet developing device according to the item, the developing unit uses a liquid developer in which toner particles are dispersed in a carrier liquid, and the cleaning unit uses the carrier liquid as the cleaning liquid. Characteristic wet developing device.