JPH06308800A - Electrifying device - Google Patents

Abstract

PURPOSE:To always keep a grid screen part in a fixed plane state without being twisted, to stably electrify a photoreceptor and to prevented the unevenness of electrification from occurring on the photoreceptor in an electrifying device in which the grid screen part and an stabilizer part are integrally formed by using a thin electrical conductive plate. CONSTITUTION:This electrifying device is formed with the grid screen part 23 at the central part of the thin electrical conductive plate along a corona electrode 22 and the stabilizer part 24 integrally with the screen part 23 by bending the electrical conductive plate on both sides in the width direction of the screen part 23 so that the plate is made groove shape. The device is provided with pressing means 27 and 28 respectively pulling the screen part 23 and the stabilizer part 24 in a longitudinal direction along the electrode 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device used for charging a photoconductor in an image forming apparatus such as a copying machine or a printer, and particularly, a grid screen part and a stabilizer part are integrally formed by a thin conductive plate. The present invention relates to a charging device formed in the above.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a photoconductor is charged by a charging device, and then the photoconductor is irradiated with light according to image information to electrostatically charge the photoconductor. A latent image is formed, and a developer is supplied to the electrostatic latent image portion from a developing device to form an image.

As a charging device for charging the photoconductor as described above, a device which charges the photoconductor by corona discharge from a corona electrode has conventionally been used, and the photoconductor is charged. In order to ensure stable and uniform operation, a scorotron type charging device is used, in which a grid made of mesh material is provided between the corona electrode and the photoconductor, and a bias voltage is applied to this grid. It had been.

Here, as such a scorotron type charging device, generally, as shown in FIG. 1, holders 2 are provided on both sides in the longitudinal direction of a stabilizer 1 formed in a groove shape.
3, a corona electrode (not shown) for corona discharge is arranged between the holders 2 and 3, and a mesh member or the like is arranged along the corona electrode in the portion of the holders 2 and 3 on the photoconductor side. The grid screen 4 thus arranged is used.

However, in such a charging device,
Since the stabilizer 1 and the grid screen 4 and the like are separately configured, the number of parts in the charging device is large, the manufacturing thereof is troublesome and the cost is high, and the stabilizer 1 and the grid screen 4 are adjusted to different potentials. There was a problem such as the necessity of increasing the size of the device.

Further, in the scorotron type charging device as described above, in order to stably and uniformly charge the photosensitive member, the grid screen 4 has a uniform planar shape between the holders 2 and 3. Had to be distributed to.

Therefore, in the above scorotron type charging device, as shown in FIG. 1, positioning projections are formed on the surfaces of the holders 2 and 3 on the photoconductor side at intervals corresponding to the width of the grid screen 4. 2a and 3a are provided,
The grit screen 4 is arranged so as to be in contact with the protrusions 2a and 3a, and one end of the grit screen 4 is attached to the terminal portion 5 provided on the one holder 2, and the grit screen 4 is also attached. The other end of the hook holder 6 is attached to the hook 6a of the hook holder 6 which is provided separately from the other holder 3, and the hook holder 6 is pushed outward by a biasing means (not shown) such as a spring. The grid screen 6 was urged to be maintained in a tensioned state.

However, when the grit screen 4 is arranged so as to be in contact with the protrusions 2a and 3a provided on the holders 2 and 3 as described above, the positions where the protrusions 2a and 3a are provided are provided. When an error occurs, this causes the grid screen 4 to be twisted in the middle, and the distance between the grid screen 4 and the photoconductor becomes inconsistent, resulting in uneven charging of the photoconductor.

Also, in the prior art, as a charging device as described above, as shown in Japanese Patent Laid-Open No. 98-98334, a shield body in which both sides of a metal screen are bent to have a groove shape, that is, a grid screen. A charging device has been developed, in which a unit in which a plate and a stabilizer are integrated is fitted into a support member made of an insulator and attached.

Here, in the charging device disclosed in this publication, when the shield body is fitted and mounted on the support member as described above, in order to prevent the shield body from being arbitrarily deformed, this shield body is generally used. It was necessary to use a thick metal plate.

However, when a grid screen such as a mesh is formed using such a thick metal plate,
That processing becomes difficult, for example, when forming a grid screen such as a mesh by punching generally performed, unless the interval of the mesh or the like in this grid screen is increased, the mesh part will be cut, Further, when the metal plate is punched out, burrs are generated around the punched portion, which adversely affects the charging of the photoconductor.

In addition, when the grid screen and the stabilizer are integrally formed and fitted into the support member as described above, the size of the shield body and the size of the fitted portion of the support member are accurately matched. If not, there is a problem that the surface of the grid screen in the shield body is distorted, and uneven charging occurs when the photoreceptor is charged.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned various problems in a charging device used for charging a photoconductor.

Here, in the charging device in which the grid screen and the stabilizing plate can be integrated and miniaturized, the present inventors do not twist the grid screen unlike the conventional charging device, and stabilize the exposure. A study was conducted to enable charging of the body.

As shown in FIGS. 2 to 4, the inventors of the present invention provided a mesh or the like along the corona electrode 11 at the center of a conductive plate having a certain thickness and rigidity. While forming the grid screen portion 12,
On both sides in the width direction of the grid screen portion 12,
The conductive plate is bent into a groove shape to stabilize the stable plate portion 1.
3 is integrally formed with the grid screen portion 12, and the holders 14 and 15 are provided on both sides in the longitudinal direction of the conductive plate formed in a groove shape by integrating the grid screen portion 12 and the stabilizer plate portion 13 in this way. , This holder 14,
In a charging device configured to hold a corona electrode 11 made of a wire between 15 in a stretched state, one locking hole 12a is provided at the center of one end portion of the grid screen portion 12 in the longitudinal direction, The locking holes 12a are provided on both sides of the other end.

On the other hand, on the side of the photoconductor 7 which is charged by the charging device, it corresponds to the respective locking holes 12a provided in the grid screen portion 12 on the support frames 8 on both sides for supporting the photoconductor 7. Locking protrusion 8a
Was set up.

The engaging projections 8a provided on the support frame 8 of the photoconductor 7 are engaged with the engaging holes 12a provided on the grid screen 12 of the charging device, and the charging is performed. The device is a biasing means such as a spring (not shown)
The charging device is urged toward the photoconductor 7 side by the above, and the charging device is set so as to be spaced apart from the photoconductor 7 by a constant distance. In this state, a voltage is applied to the corona electrode of the charging device to cause corona discharge. As described above, a bias voltage is applied to the conductive plate in which the grit screen portion 12 and the stabilizing plate portion 13 are integrated so that the photoconductor 7 is charged.

Here, as described above, the three locking holes 12a provided at each end of the grid screen portion 12 and the three locking projections 8a provided on the support frames 8 on both sides of the photoconductor 7 are provided.
When the charging device is held by the support frame 8 in a state of being supported by the charging device and being supported by the three points, the surface of the grid screen portion 12 in the charging device is not twisted, and the photoconductor 7 is fixed. It became possible to stably charge in a constant state.

However, in the case of this charging device, since the conductive plate which integrally forms the grit screen portion 12 and the stabilizing plate portion 13 has a certain thickness and is rigid, the grid screen portion 12 is provided. The problem that the processing of mesh etc. became difficult still existed.

Therefore, the inventors of the present invention twisted the grid screen portion 12 even when the grit screen portion 12 and the stabilizer plate portion 13 were integrally formed by using a thin conductive plate as described above. The present invention has been completed by further research to prevent the occurrence of charging unevenness on the photosensitive member 7 and to prevent the uneven charging of the photosensitive member 7.

[0021]

According to the present invention, in order to solve the above problems, a grid screen portion is formed along a corona electrode in the central portion of a thin conductive plate, and the grid screen portion is formed. In a charging device in which the conductive plate is bent so as to have a groove shape on both sides in the width direction of the portion, and the stabilizer plate portion is formed integrally with the grid screen portion, the grid screen portion and the stabilizer plate portion are respectively corona electrodes. A biasing means for pulling in the longitudinal direction along is provided.

Here, at least one urging means for pulling the grid screen portion and the stabilizing plate portion in the longitudinal direction along the corona electrodes is provided in the grid screen portion and the stabilizing plate portion, respectively. However, in order to more reliably suppress deformation such as twisting in the grid screen portion, it is preferable to provide biasing means on each of the stabilizing plate portions on both sides of the grid screen portion.

[0023]

In the charging device according to the present invention, the conductive plate is bent on both sides in the width direction of the grid screen so as to have a groove shape, and the stabilizer is integrally formed with the grid screen when forming the stabilizer with the thickness. Since a thin mesh is used, it becomes possible to easily form a mesh or the like in the grid screen portion.For example, when forming the mesh in the grid screen portion by punching with a press, the mesh spacing in the grid screen portion Even if it is not made large, the mesh part will not be cut, and when this conductive plate is punched, there will be no burrs around this punched part, and there will be no adverse effect when charging the photoreceptor. It has no effect.

Further, in the charging device according to the present invention, since the grid screen portion and the stabilizer portion which are integrally formed as described above are pulled in the longitudinal direction along the corona electrode by the biasing means, respectively. Even when the grid screen portion and the stabilizer portion are integrally formed by the thin conductive plate as described above, the grid screen portion is not twisted by the tension by each urging means and is in a constant plane state. As a result, the photoconductor is stably charged evenly without causing uneven charging when the photoconductor is charged.

Further, in the charging device according to the present invention, since the grid screen portion and the stabilizing plate portion are integrally formed as described above, the conventional charging device in which the grid screen and the stabilizing plate are separately provided. Compared with, the number of parts is small, the manufacturing is easy and the manufacturing cost is low, and by adjusting the position where the corona electrode is installed well, it is possible to make the grid screen part and the stabilizer part at the same potential. Therefore, the charging device can be downsized.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the charging device according to the present invention will be specifically described below with reference to the accompanying drawings.

In the charging device of this embodiment, FIG.
As shown in FIG. 8, the corona electrode 22 made of a wire was attached between the attachment portions 21a on both sides in the longitudinal direction of the elongated holder 21 made of an insulating material.

Further, along the corona electrode 22 attached to the holder 21 in this way, a grid screen portion 23 in which a large number of slits 23a are provided by punching by press at the central portion of a thin metallic conductive plate.
At the same time, the thin conductive plate is bent so as to have a groove shape on both sides in the width direction of the grid screen portion 23 so that the stabilizing plate portion 24 is formed.
It is designed to be integrally formed on both sides of.

Then, as described above, the corona electrode 22 attached to the holder 21 is covered, and the stabilizing plate portions 24 are integrally formed on both sides of the grid screen portion 23 to form a groove-shaped conductive plate. I attached it to 21.

Here, when the above-mentioned conductive plate is attached to the holder 21, its grid screen portion 23
While one end of the grid screen portion 23 is attached to the terminal portion 25 provided at one end portion in the longitudinal direction of the holder 21, the other end of the grid screen portion 23 is attached to the hook 26a of the hook holder 26 provided at the other end portion of the holder 21. Attaching the hook holder 26, the biasing means 2 comprising a spring
7, the holder 21 is urged to be pushed outward in the longitudinal direction, and the grid screen portion 23 is held in a state of being pulled in the longitudinal direction.

The stabilizers 24 on both sides, which are integrally formed with the grid screen 23, are attached to the holder 21.
When the holder 21 is attached to the holder 21, the positioning protrusions 21b are provided on both side walls of the holder 21 in the longitudinal direction so as to project outward in the width direction. The positioning projections 21b thus provided are arranged such that both longitudinal ends of the stabilizers 24 on both sides of the grid screen 23 are in contact with each other, and the stabilizers 24 are bent. At the upper end position distant from the side, the biasing means 28 made of springs are bridged over the longitudinal end portions of the stabilizing plate portions 24 and the side walls of the holder 21, respectively.
The stabilizers 24 on both sides of the grid screen portion 23 are held by being pulled in the longitudinal direction.

When the grid screen portion 23 and the stabilizing plate portions 24 bent on both sides in the width direction thereof and the biasing means 27 and 28 made of springs respectively are maintained in the state of being pulled in the longitudinal direction, the grid screen portion The part 23 is maintained in a uniform flat state without being distorted.

When the charging device of this example was used to charge the photoconductor, the photoconductor was uniformly charged without causing uneven charging or the like.

Further, in the charging device in this embodiment, the grid screen portion 23 and the stabilizing plate portion 24 are integrally formed by a thin metallic conductive plate, and the upper end of each stabilizing plate portion 24 apart from the bending side is formed. In position,
Since the lengthwise ends of the respective stabilizers 24 are held by the holder 21 in a state of being pulled by the biasing means 28 composed of springs, the thin conductive plates are bent on both sides in the width direction of the grid screen 23. When the respective stabilizers 24 are provided, even if the bending position is slightly displaced and the width of the grid screen 23 is narrowed as shown in FIG. The surface of the screen portion 23 is not twisted, and the surface of the screen portion 23 is always maintained in a uniform flat state, so that the photosensitive member can be stably charged.

[0035]

As described above in detail, in the charging device according to the present invention, the conductive plate is bent on both sides in the width direction of the grid screen so as to have a groove shape, and the stabilizer is integrated with the grid screen. Since the conductive plate having a small thickness was used for forming, the grid screen part made of mesh or the like can be easily manufactured. For example, the mesh is formed on the grid screen part by punching with a press. In this case, even if you do not increase the mesh interval in the grid screen section unlike when using a thick conductive plate, the mesh part will not be cut, and when this conductive plate is punched, this punching It does not cause burrs around the area and has a negative effect on charging the photoconductor. It was no longer say.

Further, in the charging device according to the present invention, since the grid screen portion and the stabilizing plate portion integrally formed as described above are respectively pulled by the biasing means in the longitudinal direction along the corona electrode, Even when the grid screen portion and the stabilizer portion are integrally formed by the thin conductive plate as described above, the grid screen portion is not twisted by the tension by each urging means and is in a constant plane state. As a result, the photosensitive member can be stably and uniformly charged without uneven charging when charging the photosensitive member.

Further, in the charging device according to the present invention, since the grid screen portion and the stabilizing plate portion are integrally formed as described above, the conventional charging device in which the grid screen and the stabilizing plate are separately provided. Compared with, the number of parts is small, the manufacturing is easy and the manufacturing cost is low, and by adjusting the position where the corona electrode is installed well, it is possible to make the grid screen part and the stabilizer part at the same potential. The charging device can be downsized.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a conventional charging device.

FIG. 2 is a perspective view showing a charging device in which a grid screen portion and a stabilizer portion are integrally formed by using a rigid conductive plate having a certain thickness.

FIG. 3 is a plan view showing a state on the side of a photoconductor on which the charging device shown in FIG. 2 is set.

4 is a cross-sectional explanatory view showing a state in which the charging device shown in FIG. 2 is set on a support frame of a photoconductor to charge the photoconductor.

FIG. 5 is a schematic perspective view showing a charging device according to an embodiment of the present invention.

FIG. 6 is a side view of the charging device according to the embodiment.

FIG. 7 is an explanatory bottom view of the charging device according to the embodiment as viewed from the grid screen side.

FIG. 8 is an explanatory diagram showing a state in which each of the stabilizing plate portions bent on both sides in the width direction of the grid screen portion is in contact with the positioning protrusions provided on the holder in the charging device according to the embodiment.

FIG. 9 is a diagram showing a state in which, in the charging device according to the embodiment, when the width of the grid screen portion is narrowed, each stabilizer plate is deformed well and the grid screen portion is kept in a uniform flat shape. It is a figure.

[Explanation of symbols]

 22 Corona Electrode 23 Grid Screen Part 24 Stabilizer Part 27, 28 Energizing Means

Claims (1)

[Claims] 1. A grid screen portion is formed along a corona electrode in a central portion of a thin conductive plate, and
In a charging device in which the conductive plate is bent so as to have a groove shape on both sides in the width direction of the grid screen part, and the stabilizer part is integrally formed with the grid screen part, the grid screen part and the stabilizer part are formed. A charging device, characterized in that it is provided with a biasing means for pulling in the longitudinal direction along the corona electrode.