JPS6241329Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an excess developer overflow mechanism in an electrophotographic developing device.

In wet electrophotographic development, in order to prevent edge effects and ensure image quality, two conductive electrodes are provided facing each other, a developing electrode on the image side of the photosensitive material and a back electrode on the back side. The photosensitive material is conveyed through a narrow gap formed between these, and a developer is supplied into the gap from a developer discharge section.

FIG. 1 is a sectional view showing a conventional electrophotographic developing device. The photosensitive material is conveyed along the path indicated by the broken line. The sensitive material that has passed through the entrance roller 1 is transferred to the developing electrode 2.
and a back electrode 3 provided parallel to the electrode. In order to easily convey the photosensitive material into the gap 4, the photosensitive material insertion side of the developing electrode 2 is bent diagonally upward to form a guide 5. The developer is discharged into the gap 4 from a plurality of nozzles 7 formed in the discharge pipe 6 of the developer discharge section, and in order to cause the developer to flow over the photosensitive material under its own weight, the electrodes 2 and 3 The path defined by is slightly inclined. After development, the photosensitive material passes through a squeeze roller 8 to squeeze out the developer adhering to the photosensitive material. The developer that has passed through the gap 4 is stored in a tank 9 and connected to a pump (not shown) for reuse.

The amount of developer that is circulated by the pump is determined by taking into consideration the inclination angle of the electrodes 3 and 4, the distance between the electrodes, and the like. The gap 4 between the electrodes is preferably filled with developer during operation. That is,
If the amount of developer supplied into the gap is insufficient,
An air layer forms in the gap between the electrodes, which prevents sufficient development and impairs image quality.If there is too much developer, backflow occurs, as shown by arrow A in Figure 1. , the developer adheres to the inlet roller 1, resulting in staining of the roller and deterioration of image quality. However, the discharge amount of the pump used is not constant, and it is difficult to always supply the optimum amount into the gap 4 depending on the presence or absence of the sensitive material in the gap 4.

In view of the shortcomings of the conventional technology, the present invention always supplies the optimum amount (the amount that fills the gap between the electrodes with the developer) regardless of fluctuations in the discharge amount of the pump, and prevents backflow of the developer. An object of the present invention is to provide an excess developer overflow mechanism in an electrophotographic developing device. The purpose of this invention is to prevent the developer from overflowing to the guide 5 provided on the photosensitive material insertion side of the developing electrode in order to prevent the developer from flowing back toward the inlet roller while supplying the developer at an optimum flow rate or higher. This can be achieved by forming a mouth. By forming the overflow port, excess developer can overflow onto the upper surface of the developing electrode, filling the gap defined between the developing electrode and the back electrode opposite thereto,
Moreover, backflow toward the entrance roller can be prevented. The position of the overflow port needs to be higher than the highest position of the back electrode (the side where the photosensitive material is inserted), and by forming it in the center of the width direction of the guide, the edge of the photosensitive material can be This prevents it from entering the overflow port and interfering with conveyance. The overflow port may be a notch or at least one perforation.

The excess developer release mechanism in the electrophotographic developing apparatus according to the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a sectional view of essential parts of the excess developer release mechanism according to the present invention. In the figure, elements corresponding to those shown in FIG. 1 are given the same numbers.

In the present invention, a notch 10 is formed in the center of the guide plate 5 in the width direction to remove an excess amount of the developer from the discharge pipe 6 which is supplying the developer at an optimum flow rate or higher. The liquid overflows onto the upper surface of the developing electrode 2 through the notch 10. Therefore, it is possible to completely fill the developer passage defined between the developing electrode 2 and the back electrode 3 with the developer, and it is also possible to prevent backflow toward the entrance roller 1. For this purpose, the bottom B of the notch 10 must be
is from the highest position A of the back electrode 3 on the side where the sensitive material is inserted.
Must be set low.

FIG. 3 is a perspective view showing a guide plate and a developing electrode used in the present invention.

It is desirable that the notch 10 be formed at the center of the guide plate 5 in the width direction. That is, if the notches 10 are formed at the ends in the width direction, the corners of the photosensitive material to be conveyed may get into the notches 10 and smooth conveyance may be hindered. As a precaution, the developer overflowing onto the upper surface of the developing electrode 2 does not fall from the side edges of the electrode 2. This is because the side edges of the electrode 2 are airtightly provided with side walls for bearing the rollers 1, 8, etc., although not shown.

The notch 10 may be a through hole, or a plurality of small holes may be drilled in the guide plate.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a conventional electrophotographic developing device, FIG. 2 is a cross-sectional view showing an excess developer release mechanism in the electrophotographic developing device according to the present invention, and FIG.
The figure is a perspective view showing a guide plate and a developing electrode used in the present invention. 1... Entrance roller, 2... Developing electrode, 3... Back electrode, 4... Gap, 5... Guide, 6... Discharge pipe, 7... Nozzle, 8... Squeeze roller, 9... Tank, 10...Overflow port.

Claims (1)

[Scope of utility model registration request] A discharge section that discharges a developer in the width direction of the photosensitive material, a developing electrode that is inclined downward toward the downstream side of the discharge section, and a back surface that is opposite to and parallel to the developing electrode below. comprising an electrode and a guide integrally provided upward on the side of the developing electrode into which the sensitive material is inserted, and transporting the sensitive material into a gap defined between the developing electrode and the back electrode; In an electrophotographic developing device that fills the developer solution in the gap, an overflow port is provided at the center in the width direction of the guide, and the height of the bottom of the overflow port is equal to the highest position of the back electrode on the side where the photosensitive material is inserted. An excess developer overflow mechanism characterized in that the excess developer overflows onto the upper surface of the development electrode through the overflow port by discharging the developer at an optimum flow rate or higher from the discharge portion.