JPS6013183B2 - Rinse/squeeze device for electrophotographic developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot electrophotographic apparatus, and more particularly to an electrophotographic developer rinsing/squeezing apparatus that allows the use of a highly concentrated developer and provides high quality images.

FIG. 1 shows a conventional electrophotographic wet-type developing device, in which a developing electrode 3 having a developer counterfeit portion 3a is positioned below a recording medium 2 stuck to a flat plate 1. The surface of the recording medium 2 developed with the jet developer is squeezed by a squeeze roller 4 adjacent to the developing electrode 3, and then transferred to a fixing device.

Therefore, according to such a squeeze method, since the developer is only removed by the assisted contact of the squeeze roller 4, so-called background fogging occurs when a high concentration developer is used. In particular, in color copying, since the above-mentioned development and squeeze processing is repeated several times, fog density accumulates, making it difficult to obtain high-quality images. In addition, the squeeze roller 4 has the problem that if the contact pressure is weak, the liquid cannot be completely removed, and if the contact pressure is too strong, the image surface becomes rough. There is a problem with toner or other contaminants being transferred to the developing surface. In order to solve the various problems of wet-type electrophotographic devices as described above, the present invention enables the use of high-density developer and provides high-quality images by being incorporated between a developing device and a fixing device. Rinsing of electrophotographic developer. This paper proposes a squeeze device. The details of the present invention will be explained below with reference to FIGS. 2 to 4.

FIG. 2 is a schematic diagram of the first embodiment of the apparatus according to the present invention, in which the rinse/squeeze apparatus A of the present invention is placed in the developing apparatus B in the feeding direction x of the recording medium 2 conveyed by the flat plate 1.
located next to.

In this case, the auxiliary roller 10, which is incorporated in the same position as the squeeze roller of the conventional developing device B, is used as a stepped roller as shown in FIG. It is configured to have a space LI of about several hundred mountain slopes between it and the surface of No. 2. In other words, with this configuration, the rinse/squeeze device A can be used without staining the image.
It is possible to prevent the developer from flowing into the container. The rinse/squeeze device A includes a plate-shaped rinse head 11 that forms a small space L2 between it and the recording medium 2, and a rinse liquid is supplied to the cardia 11a of the rinse head 11 from a pump 12A, which will be described later. Ru. The cardia 11a of the rinse head 11 is located at a position as close to the developing device B as possible, since the rinsing liquid flows in the opposite direction to the developing device B as the recording medium 2 moves. Good. As the rinsing liquid used in the rinsing/squeezing device A of the present invention, an electrically insulating liquid used as a solution of a general liquid developer, for example, Isovar Nippon Liquid (trade name) can be used. Of course, the rinse head 11 needs to be configured so that a uniformly flowing, laminar stream of rinse liquid is formed along its surface, but this is easily achieved from known techniques. According to the present invention, a squeeze roller 12 that is pressed against the surface of the recording medium 2 is positioned adjacent to the right side of the rinse head 11 .

The squeeze roller 12, which is synchronously driven to have a circumferential speed that is synchronized with the moving speed of the recording medium 2, covers a highly elastic core layer 12a and the outer periphery of this core layer 12a, making the surface rough. It is made from a double mechanized roller consisting of a liquid-permeable four-layer outer layer 12b. A preferred structure for this squeeze roller 12 is that the core layer 12a is made of a sponge made of nitrile ptagene rubber with excellent oil resistance, and the outer layer 12b is made of a sponge made of nitrile ptagene rubber with excellent oil resistance, and the outer layer 12b is made of a sponge with a grain-like surface treatment and has low liquid permeability. It is best to use nitrile butadiene rubber or urethane. The squeeze roller 12 has a core layer 12a made of highly elastic nitrile-butadiene rubber or urethane with a hardness of 100 to 400, and a core layer 12a made of nylon, polyvinyl alcohol, polystyrene, vinyl chloride,
A combination of outer layer 12b made of resin such as vinylidene chloride may also be used. Note that the material 13 in contact with the squeeze roller 12 is a cleaning member such as a sponge or felt that removes toner adhering to the circumferential surface of the squeeze roller 12; This can be omitted if the process itself has been subjected to transfer prevention treatment. The rinse/squeeze device A has a receiver 14 that accommodates the rinse head 11 and squeeze roller 12, and the rinse liquid flowing down the receiver 14 is collected in a collection tank 16 through a communication pipe 15.

Inside the collection tank 16, there is an electrode plate 16a configured in a labyrinth shape, and a voltage of opposite polarity to that of the developer toner is applied to this electrode plate 16a. is electrostatically attracted. A pump 12A is connected to the collection waste 16, and the electrode plate 16a is connected to the pump 12A.
The rinse liquid purified by this is circulated and pressure-fed toward the nuchal portal portion 11a. Since the apparatus of the embodiment has the structure as described above, the developer attached to the developed recording medium 2 is auxiliary. A portion is removed by the roller 10. Then, as the flat plate 1 moves, the adhering developer is rapidly diluted by the rinsing liquid on the rinsing head 11. Therefore, since the image that has been developed is prevented from further progressing, it is possible to use a high-concentration developer. Then, the background fog toner generated on the recording medium 2 is floated and flowed down by the flow of the rinsing liquid on the rinsing head 11, and the image quality of the image is improved. In this case, the toner attached to the charged portion of the recording medium 2 is
Since it is in an electrostatically adsorbed state, it does not peel off easily, so the image formed will not be damaged by the use of the rinsing liquid. In the subsequent squeezing action of the surface of the recording medium 2 by the squeeze roller 12, a sufficient squeezing action can be provided because the developer has already been diluted with the rinsing liquid and there is almost no floating toner. Further, since the squeeze roller 12 is hardly contaminated by floating toner, it is always in a clean state, and there is no problem of reverse transfer due to the squeeze roller 12 being soiled. Further, since the toner mixed in the rinsing liquid is electrostatically attracted to the electrode plate 16a of the collection tank 16, the clean rinsing liquid can be constantly circulated. FIG. 4 shows a second embodiment of the present invention, partially enlarged.
Components that are the same as those in the figure are designated by the same reference numerals as in FIG. 2.

The feature of this embodiment is that the rinse head 11A is used as an electrode plate, and a reverse bias voltage (for example, 5 W) having a polarity opposite to that of the toner is applied to the rinse head 11A. According to the rinse head 11A, the toner in the excess developer that adheres to the recording medium 2 is electrostatically attracted to the rinse head 11A.
2, the floating toner on the surface of the recording medium 2 is almost completely eliminated. According to the experiment conducted by the present inventor, the toner deposited on the rinse head 11A is pushed by the pressure of the rinse liquid jet and flows out of the rinse head 11A appropriately.
It has been found that there is almost no need for regular or irregular maintenance of the rinse head 11A. In the above embodiments, the case of a flat recording medium was exemplified, but it goes without saying that the present invention can also be applied to a drum-shaped recording medium.

As is clear from the above description, the present invention has the following effects.

a) It becomes possible to use a high concentration developer.

b) Since background fog can be removed, image quality can be improved, and is particularly effective for color copying where background fog is likely to accumulate.

c. By applying fin pressure of opposite polarity to the toner or by using a rinse head that does not apply voltage, staining of the squeeze roller can be prevented and reverse transfer from the squeeze roller can be prevented.

d) Maintenance of the squeeze roller can be omitted, or at least the time required for maintenance can be extended.

e The use of double-layered squeeze rollers provides a squeezing effect that does not disturb the formed image.

f) It is economical because clean liquid can be constantly circulated by using a collection tank with an electrode plate.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional electrophotographic overflow type developing device, FIG. 2 is an overall configuration diagram of the first embodiment of the device of the present invention, and FIG.
FIG. 4 is a sectional view taken along the line mm in the figure, and an enlarged view of the main parts of the apparatus according to the second embodiment of the present invention. A... Rinse/squeeze device, B... Developing device, 10.
... Auxiliary roller, 11, 11A ... Rinse head, 12 ... Squeeze roller, 14 ... Receiver,
16... Recovery tank, 16a... Electrode plate. Z box O 2 diagram O 3 diagram Guy diagram

Claims (1)

[Scope of Claims] 1. In an electrophotographic wet-type developing device that visualizes an electrostatic latent image on a recording medium by a liquid development method, a device located adjacent to the electrophotographic wet-type developing device in the moving direction of the recording medium; a plate-shaped rinse head provided to form a small space between the rinse head and the recording body; a pump that spouts a rinse liquid into the space between the rinse head and the recording body;
A rinsing/squeezing device for an electrophotographic developer, comprising: a squeeze roller positioned adjacent to the rinse head in the moving direction of the recording body and driven in synchronization with the recording body to squeeze a developing surface. 2. A rinse/squeeze device for an electrophotographic developer according to claim 1, wherein the cardia of the rinse head is provided at a position closer to the electrophotographic wet developing device. 3. In the rinse/squeeze device according to claim 1, the squeeze roller has a core layer made of an elastic material such as sponge, and an outer layer made of a smooth, liquid-permeable small rubber layer. An electrophotographic developer rinsing/squeezing device consisting of: 4. In an electrophotographic wet-type developing device that visualizes an electrostatic latent image on a recording medium using a liquid development method, an electrophotographic wet-type developing device that is located adjacent to the developing device in the moving direction of the recording medium and between the recording medium and the recording medium. A plate-shaped rinse head that is provided to form a small space and to which a reverse bias voltage having a polarity opposite to that of the toner is applied, a collection tank that receives the rinse liquid flowing down on the rinse head, and a rinse head in the collection tank. An electrophotographic developer comprising: a pump that circulates and pressure-feeds a liquid to the rinse head; and a squeeze roller that is positioned adjacent to the rinse head in the direction of movement of the recording medium and is driven in synchronization with the recording medium to squeeze the developing surface. Rinse/squeeze device. 5. The rinse/squeeze device for an electrophotographic developer according to claim 4, wherein the collection tank includes an electrode plate to which a reverse bias voltage having a polarity opposite to that of the toner is applied. Device.