JPH02212858A - Corona discharging device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a corona discharge device used in image forming apparatuses and the like.

[Prior Art] Conventionally, corona dischargers having a grid electrode that controls the charged body to have a desired potential have been divided into two types: one in which the grid is positioned and fixed to the charger, and the other in which the grid is positioned and fixed to the charger, and the one in which the grid is fixed to the charger as shown in Fig. 3. In order to determine the distance between the photoreceptor surface as a charged body, a coil spring 3 is passed between the corona discharger 1 and the grid 2, and is pressed against the photoreceptor 4 to be charged via a spacer 5 to determine the distance between the grid and the photoreceptor surface. It is known that the structure determines the

[Problems to be Solved by the Invention] However, although it is possible to maintain the corona radiation tM and the dimensional accuracy between the grids in the conventional example in which the grid is fixed to the corona discharger, the surface of the photoreceptor is susceptible to rotational runout. There is a problem that it is difficult to maintain the accuracy of the distance between the grid and the grid. In addition, maintaining the accuracy of the distance between the photoreceptor surface and the grid was improved by passing a coil spring between the grid and the corona discharger and lightly pressing the grid against the photoreceptor through a spacer. There were drawbacks such as:

That is, since the coil spring 2 is hung on the outside of the corona discharger, there are cases where the spring is accidentally touched and the spring is dislodged or deformed.

In particular, in recent miniaturized devices, the surrounding space is reduced due to the use of smaller-diameter photoreceptors.As a result, when miniaturizing the corona discharger, the protrusion of the spring on the outside of the corona discharger becomes an obstacle. It had become.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to make it possible to downsize and simplify a corona charging device.

[Structure of the Invention] In order to achieve the above object, the present invention provides a corona that includes a control electrode that controls the charging potential of an object to be charged, and a positioning member that maintains a predetermined distance between the control electrode and the object to be charged. In the discharge device, the control electrode has elasticity, and its elastic force brings the positioning member into pressure contact with the object to be charged.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIGS. 1 and 2 show a corona discharge device that can be used in an electrophotographic image forming apparatus as an embodiment of the present invention.

A corona discharger l for charging a photoreceptor, which is an object to be charged, has blocks 7 made of resin at both ends of a shield plate 6 made of stainless steel.
8 is fixed, and a discharge wire 9 made of tungsten wire plated with gold is stretched between them. The bottle 7a protruding from the block fits into a hole in the side plate 10 supporting the photoreceptor drum 4, and the block 8 fits into a hole in the side plate 11.
It is fixed by fitting the tip of the bottle 12 inserted from the outside. Reference numeral 2 denotes a grid plate, which is made of a metal plate such as a stainless steel plate for springs and has mesh openings 2a formed therein by etching or pressing. Further, a predetermined potential is applied to the grid plate 2 serving as a control electrode, and when a voltage is applied to the discharge wire 9, the potential applied to the grid plate 2 is controlled so that the potential at which the photoreceptor 4 is charged becomes a predetermined potential. be done. Spacers 5 made of sliding resin and serving as positioning members for keeping the grid plate 2 and the photoreceptor 4 at a predetermined distance are fixed to both ends of the grid plate 2 by heat welding. Bending processes 2b and 2° are performed for reinforcement, and on the outside of the spacer 5 there are plate spring portions 2d and 2@ that are flat and protrude. The tips of the temporary spring parts 2d and 2e abut against parts 6m and 6b of the shield plate 6 of the corona discharger, and the plate spring parts 2d.

It is pressed against the photoconductor 4 through the spacer 5 by the reaction force due to the spring property of 2e, ensuring a distance between the photoconductor surface and the grid, eliminating the effects of vibrations, etc. of the photoconductor surface during rotation. ing. Therefore, in the corona discharge device, the grid plate 2 for controlling the surface potential of the photoreceptor 4 and the photoreceptor 4 are maintained at a constant distance, and the photoreceptor 4 can be uniformly and satisfactorily electrified. Further, the plate spring portions 2d, 2e and the shield plate 6 are in contact with each other to maintain electrical continuity.

FIG. 4 is a perspective view showing another embodiment of the corona discharge device of the present invention. In the above embodiments, the grid was made of a metal plate, but in this embodiment, the grid is made of a thin wire such as a tungsten wire. Reference numeral 13 is a grid wire which is bent in order from hooks 14a and 14b of the frame body 14. A vertically movable spacer 5 is arranged on the frame, and when the spacer 5 comes into contact with the photoreceptor, the grid wire 13 bends, and the grid wire 1 conversely bends.
3 presses the photoreceptor through a spacer 5 to maintain a predetermined distance between the grid wire 13 and the photoreceptor.

[Effects of the Invention] As explained above, according to the corona discharge device of the present invention, the control electrode that controls the charging potential of the photoreceptor has elasticity,
Since the positioning member that maintains the control electrode and the charged object at a predetermined distance by its elastic force is pressed against the charged object, the device can be simplified, the corona discharge device can be made smaller, and the entire device using this discharge device can be simplified. This has the effect of making it possible to downsize.

[Brief Description of the Drawings] Fig. 1 is a sectional view showing an embodiment of the corona charging device of the present invention, and Fig. 2 is a perspective view of a grid and a shield plate showing an embodiment of the corona discharging device of the present invention. , 'fS3 is a sectional view of a conventional corona discharge device, and FIG. 4 is a perspective view showing another embodiment of the corona discharge device of the present invention. 1 is a corona charger, 2 is a grid plate, 3 is a coil spring,
4 is a photoreceptor, 5 is a spacer, 6 is a shield plate, 7.8
is block, 13 is grid wire

Claims (1)

[Claims] In the corona discharge device, the control electrode includes a control electrode that controls the charging potential of a charged object, and a positioning member that maintains a predetermined distance between the control electrode and the charged object, and the control electrode has elasticity. A corona discharge device characterized in that the positioning member is brought into pressure contact with the object to be charged.