JPH0244300Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to the improvement of a liquid developing device, and more specifically, it prevents the recording medium from being contaminated by the developer when the development is restarted after the development of the recording medium in the developing device is completed. It concerns a new structure that has been prevented.

Conventionally, liquid developing devices have been used in electrostatic printers, copying machines, facsimile receivers, and the like. As shown in the schematic perspective view of FIG. 1, this liquid developing device includes a developing device 1 having a developing chamber 11.
, a developer inlet pipe 2 and an outlet pipe 3 provided at the bottom of the developing device 1 , a vacuum pump 4 , and a developer storage container 5 . FIG. 2 is a cross-sectional view of the conventional developing chamber 11. consists of a plurality of tanks in which metal plates 15 and 16 having protrusions 15a formed by etching are pressed and fixed. Further, the bottom plate 14 is provided with an inlet pipe 2 and an outlet pipe 3 for the developer.

In the developing operation, the electrostatic latent image forming surface of the roll-shaped or sheet-shaped recording medium (paper) 6 is
When the developing chamber 11 is closed by being sucked into contact with the loading side sliding contact portion 12a and the loading side sliding contact portion 13a of the developing chamber 11 by the action of the vacuum pump 4, the developer is drawn into the storage container due to the vacuum pressure inside the developing chamber. 5 to the developing chamber 11 via the introduction pipe 2. The developer introduced into the developing chamber 11 sequentially flows through the gap formed between the metal plate 15 and the metal plate 16 (the gap formed by the protruding portion 15a), fills the developing chamber 11, and then flows between the metal plate 16 and the recording paper 6. A developing solution film is formed in the minute gap, and the electrostatic latent image is thereby developed. Further, surplus developer in the developing chamber 11 is circulated to a storage container 5 through a discharge pipe 3.

However, in the conventional liquid developing device, when development is completed and the operation of the vacuum pump 4 is stopped, the pressure inside the developing chamber 11 returns to atmospheric pressure, and the vacuum pressure during development causes suction toward the developing chamber 11. The recording paper 6 returns to its free position, but at this time, the surface tension of the developer remaining in the developing chamber causes the developer to adhere to the recording paper 6, and a portion of the developer adheres to the recording paper 6 due to capillary action. invade the gap between However, when the developing operation is restarted, the recording paper 6 is again sucked toward the developing chamber 11 by the vacuum pressure. At this time, the facing surface of the developing chamber 11 and the sliding contact portion 12 on the loading side
The developer adhering to a is drawn into the developing chamber 11 as the recording paper 6 moves and mixes with the developer in the developing chamber 11, but the developer that has entered the sliding contact portion 13a on the delivery side is left behind. The surface of the recording paper 6 being conveyed is contaminated until the residue is exhausted. Such contamination often extends to the next electrostatic recording position, causing deterioration in print quality on the recording paper 6.

An object of the present invention is to provide a liquid developing device that eliminates contamination of recording paper when restarting operation of the liquid developing device and always performs stable development. In order to achieve the above object, the liquid developing device according to the present invention reduces the sliding contact area of the outer frame on the delivery side to minimize the amount of developer that enters there, and also allows the developer that enters the frame to be easily discharged. It is characterized by the following.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 is a sectional view showing an example of a liquid developing device according to the present invention. In FIG. 3, the thickness of the upper end surface sliding contact portion 13a of the outer frame 13 constituting the side wall on the paper exit side of the developing chamber is reduced to reduce the area of the sliding contact portion with respect to the paper, and an inclined surface is provided on the outside. , is different from the structure shown in FIG. 2 in that the outer frame 12 is steeper than the outer frame 12 on the carry-in side, so that the developer that has entered the gap can be easily discharged. With this structure, the developer that has entered the delivery-side sliding contact portion 13a oozes out of the developing chamber 11 when development is completed, making it possible to minimize the amount of developer remaining in the delivery-side sliding contact portion 13a. . Therefore, it is possible to eliminate the contamination of the recording paper 6 caused by the residual developer when the development is restarted.

Here, the outer frames 12 and 13 on the carry-in side and the carry-out side are fixed to the bottom plate 14 and the developing chamber 11 with screws.
In addition, the metal plates 15 and 16 are press-fixed inside the developing chamber 11, and since the inside of the developing chamber 11 operates under vacuum pressure during development, it is considerably difficult to operate from a mechanical and pressure-resistant perspective. The plate thickness is required. Thus, the sliding contact portions 12a, 13a on the loading side and the loading side
As the outer frames 12 and 13 for supporting the side walls, stainless steel plates with a thickness of about 6 mm are generally used from the viewpoint of holding the composite structure of the developing chamber 11 with high precision. Conventionally, the corners have only been chamfered so as not to obstruct paper transport. In contrast, in the present invention, the thickness of the upper end surface sliding contact portion 13a of the outer frame 13 on the unloading section side is reduced to about 0.5 to 1 mm,
In addition, an inclined surface is provided continuously on the sliding contact portion to encourage the discharge of residual developer, thereby eliminating contamination of the recording paper 6 while maintaining the mechanical strength of the side wall. By chamfering the thickness of the sliding contact part to about 1/5 of the side wall thickness as described above, even when recording is restarted after a long stop, there will be no contamination that will interfere with the next recording position. This has been experimentally clarified. Further, as shown in Fig. 4, the structure of the carrying-out outer frame 13 is a plate-like structure with a reinforced part, and the thickness of the carrying-out side sliding contact part 13a is set to 0.5 to 1.
A similar effect can be obtained by using mm.

As is clear from the above description, according to the liquid developing device of this invention, the thickness of the sliding contact portion on the delivery side is reduced to about 1/5 or less of the thickness of the side wall of the frame body, thereby increasing the sliding contact area with the paper. By simply forming a small size, contamination of the recording paper, which has been a problem with conventional apparatuses, can be solved, and the effect on improving development quality is extremely large.

[Brief explanation of the drawing]

Figure 1 is a schematic perspective view showing a liquid developing device, Figure 2 is a schematic perspective view showing a liquid developing device;
The figure is a cross-sectional view of a conventional developing chamber, FIG. 3 is a cross-sectional view of a developing chamber showing one embodiment of the present invention, and FIG. 4 is a cross-sectional view of an outer frame on the output side showing another embodiment of the present invention. . 1...Developer, 2...Introduction pipe, 3...Discharge pipe,
4...Vacuum pump, 5...Storage container, 6...Recording medium, 11...Development chamber, 12...Outer frame on the carry-in side, 1
2a...Sliding contact part on the loading side, 13...Outer frame on the loading side, 1
3a...Sliding contact part on the unloading side, 14...Bottom plate, 15...
Metal plate, 15a... Protrusion, 16... Metal plate.

Claims (1)

[Claims for Utility Model Registration] When the developing chamber 11 of the developing device 1 is closed on the surface of the recording medium 6 on which the electrostatic latent image is formed, the vacuum pump 4 installed on the discharge side of the developer circulation path A liquid configured to operate by introducing a developer from an external storage container 5 into the developer chamber to develop the electrostatic latent image on the recording medium and to return surplus developer to the storage container. In the developing device, among the four side walls having flat recording medium sliding contact portions on the same surface constituting the frame of the developing chamber 11, a recording medium sliding contact portion 1 on the side wall on the recording medium unloading portion side
A liquid developing device characterized in that the thickness of the side wall portion 3a is formed thinner than the other side wall portions to reduce the area of sliding contact with the recording medium.