JPH04287061A - charging device - Google Patents

Abstract

PURPOSE:To always stretch a discharge control electrode with a desired tensile force in a constant state with a small number of components, to stably stretch the discharge control electrode, and to enable it to be removed with superior operability. CONSTITUTION:The discharge control electrode 5 is stretched by connecting to the control electrode connecting part 9a of a connecting member 9 whose other terminal is mounted on a supporting member 3 on one side in such a way that it can be turned in a state where one terminal of the discharge control electrode 5 is engaged with a fixed member 8 fixed on a supporting member 2 on one side, and connecting one terminal 9c to a turn blocking claw 11, and the desired tensile force is applied to the discharge control electrode 5 by the tensile force functioning part 9b of the connecting member 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for an image forming apparatus using an electrophotographic process, and more particularly to a charging device suitable for use in a charger that charges a photoreceptor by cathodic discharge.

0002

2. Description of the Related Art Conventional charging devices include those described in, for example, Japanese Utility Model Publication No. 62-26760 and Japanese Utility Model Application Publication No. 62-30268. The former charging device is
A fixed first engaging member that holds one end of a grid plate, which is a discharge control electrode arranged at a predetermined interval on the surface of the photoreceptor, and a movable first engaging member that holds the other end of the grid plate. A second engaging member and an urging member that applies a predetermined tension to the grid plate by urging the second engaging member in a direction in which the distance between the second engaging member and the first engaging member is widened are provided. First and second positioning members are provided, respectively, which contact the surface and regulate the position of the tension member.

In the latter charging device, an impedance element is electrically connected to a grid that covers at least a portion of the corona discharge wire, and a spring is attached to one end of the grid to apply tension to the grid. One terminal of the impedance element is connected to.

0004

[Problems to be Solved by the Invention] However, in the case of the former charging device, the locking member of the discharge control electrode and the member that applies tension are separate parts, which increases the number of parts and makes it difficult to separate them. There was a problem in that it took a lot of effort to assemble. In addition, when attaching or removing the control electrode, the locking member had to be slid linearly in the direction of action of the tension biasing member and retracted. There have been problems in that the desired tension may not be obtained due to the frictional force generated during sliding or getting caught on other members.

In the latter case, one end of the grid is attached to the tongue of the spring to apply tension, so the method of fixing the spring is unstable and it is difficult to maintain a constant tension. However, the operability when removing the grid was also poor.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to enable a discharge control electrode such as a grit plate to be constantly tensioned with a desired tension using a small number of parts. Another object is to be able to mount the discharge control electrode with good stability and to improve operability when removing it.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a discharge control electrode that covers at least a portion of the discharge electrode, and a discharge control electrode that is fixed relative to the surface of a photoconductive photoreceptor. each positioning member holds the vicinity of both ends on the supporting member so as to keep the distance from each other, the fixing member fixes one end of the discharge control electrode to one of the support members, and the other end of the discharge control electrode is engaged. In the charging device, the locking member is rotatably attached to a support member on the opposite side of the fixing member, and the control electrode locks an end of the discharge control electrode to the locking member. A locking portion and a tension acting portion for applying tension to the discharge control electrode in the locked state are provided, and one end of the tension acting portion is releasably locked to prevent rotation of the locking member. A rotation prevention pawl is provided to prevent rotation. The discharge control electrode is preferably formed using a thin plate metal material.

[0008]

[Operation] According to the charging device configured as described above, one end of the discharge control electrode is fixed to one support member by the fixing member, and the opposite end is rotatably attached to the other support member. Since the control electrode is locked to the control electrode locking portion of the locking member, if one end of the tension acting portion of the locking member is locked to the rotation prevention pawl, the discharge control electrode is held in a predetermined position by the tension acting portion. It can be tensioned with a tension of

[0009] Then, if the locking of the tension acting portion by the rotation preventing claw is released, the locking member can be rotated freely, so that by rotating the locking member, the discharge by the control electrode locking portion can be prevented. The control electrode can be unlocked and easily removed.

Furthermore, if the discharge control electrode is formed of a thin plate-shaped metal material, it can be more stably tensioned by the locking member, and tension can also be effectively applied thereto.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partially cutaway front view of a charging device according to the present invention.

This charging device has left and right supporting members 2 each formed of an insulating material and sandwiching a shield case 1.
, 3, a discharge control electrode (grid) 5 covering the upper part of the discharge electrode 4, and a discharge control electrode (grid) 5 extending between the discharge electrodes 4 and 3. positioning members 6 and 7 that hold the vicinity of both ends on support members 2 and 3, respectively, and a fixing member 8 that fixes one end of the discharge control electrode 5 on the left side in FIG. 1 to one of the support members 2. , and a locking member 9 that locks the other end of the discharge control electrode 5.

Then, the locking member 9 is attached to the support member 3 on the opposite side to the side where the fixing member 8 is provided, as shown by the arrow A in FIG.
and a control electrode locking part 9 that is attached so as to be rotatable in the opposite direction and that locks the end of the discharge control electrode 5 to the locking member 9.
a, and a tension acting part 9b for applying tension to the discharge control electrode 5 in the locked state, and one end 9c of the tension acting part 9b is releasably locked to release the locking member 9. Rotation prevention claw 11 movable in the direction of arrow B to prevent rotation
has been established.

The discharge electrode 4 is formed of a thin wire material such as tungsten or amorphous metal, and is fixed to the support member 2 with one end connected to the power supply terminal 12, and the other end connected to the power supply terminal 12 via a spring (not shown). Attached to the support member 3,
The power supply terminal 12 is connected to a high-voltage power source to perform discharge, and efforts are made to stabilize the discharge performance by using the discharge control electrode 5 (in the case of cathode discharge).

The discharge control electrode 5 is made of, for example, a thin metal material, and is formed into a desired lattice shape by etching or electroforming, as shown in FIG. And hook-shaped fixing members 8, 8 (Fig. 1) are attached to the left end.
Square holes 5a, 5a that engage with the control electrode locking portion 9a of the locking member 9 are formed at the right end, respectively.

Then, the discharge control electrode 5 is held in a state in which the square holes 5a, 5a on the left end side are engaged with the fixing members 8, 8 (one set is arranged in the front and rear) as shown in FIG. , the control electrode locking part 9a of the locking member 9 is engaged with the square holes 5b, 5b at the right end, and the positioning member 6 is placed on the lower surface side of the locking member 9.
, 7 are arranged near the fixing member 8 and the locking member 9, respectively, to maintain a constant distance L between the surface 13a of the photoreceptor 13, which is the object to be charged, and the discharge control electrode 5. .

As shown in FIG. 3, the locking member 9 is formed by bending the entire thin plate material so that the cross-sectional shape at approximately the center is U-shaped. A pair of control electrode locking parts 9a, 9a are formed, and a tension acting part 9b is formed at the rear, extending rearward while changing the width of the ceiling part, and a part is cut out below both sides. The holes 9d and 9d are formed at corresponding positions, respectively.

As shown in FIG. 4, the holes 9d and 9d on both sides are fitted with rotary shafts 3a and 3a (only one side is shown) formed in the support member 3 in correspondence with the holes. By doing so, the locking member 9 becomes rotatable in the direction of arrow A in FIG. Each of the rotating shafts 3a is shown in FIG.
Inverted D with a part of the outer peripheral surface formed into a flat shape as shown in
By rotating the locking member 9, the notch 9 of the hole 9d is formed at the minimum outer diameter dimension Dmin of the rotating shaft 3a.
At the position shown in FIG. 4 where the width L1 of e matches, the locking member 9
becomes detachable from the rotating shaft 3a.

The position where the locking member 9 can be removed is a position further rotated in the direction of arrow A than the position where the discharge control electrode 5 can be removed as shown in FIG. When tensioning the discharge control electrode 5 with a predetermined tension, this locking member 9 is used for the square hole 5a on the left side shown in FIG. is engaged with the hook-shaped fixing member 8 shown in FIG.
, 7.

Next, the square hole 5b on the right side of the discharge control electrode 5
The control electrode locking portion 9a of the locking member 9 is inserted from below, and the locking member 9 is rotated in the direction opposite to arrow A. As shown in FIG. 1, one end 9 on the rear end side of the tension acting portion 9b
c is engaged with the claw portion of the rotation preventing claw 11 correspondingly provided on the upper surface of the support member 3 as shown. At this time, the rotation preventing claw 11 is displaced in the direction of arrow B by the elastic force of the material itself due to the external force applied by the locking member 9, and when the one end 9c of the locking member 9 engages with the claw portion,
Return to the original position again.

In this state, the discharge control electrode 5 is maintained at a constant distance from the surface 13a of the photoreceptor 13, which is the object to be charged, at a predetermined tension so as to maintain and exhibit sufficient control performance. It becomes a suspended state.

Furthermore, when removing the discharge control electrode 5, the locking member 9 is rotated in the direction of arrow A after retracting the rotation preventing claw 11 from the position shown in FIG. 1 in the direction of arrow B. to the position shown in Figure 5. Then, the control electrode locking part 9a comes out of each hole 5b shown in FIG. 2 of the discharge control electrode 5 and retreats.
The discharge control electrode 5 becomes removable.

As described above, in this embodiment, the locking member 9
The discharge control electrode 5 can be attached and detached by simply rotating the electrode. Further, in this embodiment, the discharge control electrode 5
In the tensioned state, one end 9c of the tension acting part 9b of the locking member 9 is locked by the rotation prevention pawl 11, and the tension acting part 9b having elasticity applies a predetermined amount to the discharge control electrode 5 in the tensioned state. Therefore, the locking member 9 also functions as a member that applies tension.

The magnitude of the tension applied to the discharge control electrode 5 by the locking member 9 is determined by the distance L2 between the square holes 5a and 5b formed at both ends of the discharge control electrode 5 as shown in FIG.
, the rotation stop position of the locking member 9 when the discharge control electrode 5 is stretched, and the elastic deformation when the locking member 9 is locked with the rotation prevention claw 11 as shown in FIG. It is determined by the amount of deflection h etc.

Furthermore, the tension of this discharge control electrode 5 is as shown in FIG.
The length L3 of the tension acting portion 9b of the locking member 9, its plate width, plate thickness, material, the distance between the control electrode locking portion 9a and the hole 9d, and the distance between the one end 9c of the tension acting portion 9b and the hole 9d, as shown in FIG. A desired value can be obtained by appropriately selecting the distance ratio and the like.

[0026] In the above embodiment, an example was shown in which the discharge control electrode was formed of a thin metal material, but the discharge control electrode was formed of a thin metal wire material similar to the discharge electrode 4 in Fig. 1. There may be.

Further, the charging device according to the present invention is particularly effective for charging devices of image forming apparatuses using electrophotographic processes that require cathodic discharge, such as organic photoconductors (OPC photoreceptors).

[0028]

[Effects of the Invention] As explained above, according to the present invention, the locking member has the function of locking one end of the discharge control electrode and the function of applying tension to the discharge control electrode, and rotates the locking member. The discharge control electrode can be tensioned at a predetermined tension or removed by simply moving the electrode, which improves operability when attaching and detaching the discharge control electrode, and also improves the ease of attaching and detaching the discharge control electrode. It requires fewer points.

Furthermore, if the discharge control electrode is formed of a thin metal material, it can be tensioned with good stability by the locking member, and tension can also be effectively applied thereto.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a charging device that is an embodiment of the present invention.

FIG. 2 is a plan view showing a discharge control electrode 5 provided in the charging device.

FIG. 3 is a perspective view showing a locking member 9 similarly provided in the charging device.

[Fig. 4] Hole 9d, which is also the center of rotation of the locking member 9.
FIG. 3 is a perspective view showing a rotating shaft 3a fitted therein.

5 is a schematic diagram showing a state in which the locking member 9 in FIG. 3 has been rotated to a position where the discharge control electrode 5 can be removed.

FIG. 6 is an explanatory diagram for explaining the deflection amount h of the locking member 9 when the locking member 9 is locked.

[Explanation of symbols]

1 Shield case
2, 3 Support member 4 Discharge electrode
5 Discharge control electrodes 6, 7 Positioning member
8 Fixed member 9 Locking member
9a Control electrode locking part 9b Tension action part
11 Rotation prevention claw

Claims (2)

[Claims] 1. A discharge control electrode that covers at least a portion of the discharge electrode, and a support member at each end of the discharge control electrode so as to maintain the discharge control electrode at a constant distance from the surface of the photoconductive photoreceptor. In the charging device, the charging device includes positioning members for holding, a fixing member for fixing one end of the discharge control electrode to the one support member, and a locking member for locking the other end of the discharge control electrode. a control electrode locking portion that rotatably attaches a locking member to a supporting member opposite to the fixing member, and locks an end of the discharge control electrode to the locking member;
A tension acting part is provided for applying tension to the discharge control electrode in the locked state, and one end of the tension acting part is releasably locked to prevent rotation of the locking member. A charging device characterized by being provided with a blocking claw. 2. The charging device according to claim 1, wherein the discharge control electrode is made of a thin plate-like metal material.