JPH09185223A - Corona discharging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a corona discharging device which has an easiness for handling, whose assembling and maintenance are easy without hurting the hand and the finger of an operator, and whose electrode can be easily exchanged by closely sticking a corona discharging electrode to an insulating substrate, providing a leading end part on a position which does not protrude from the insulating substrate, and making the corona discharging electrode exchangeable. SOLUTION: As to a saw-toothed electrode board 70 provided on a corona charger 11; a saw-toothed electrode 111 is integrally formed on the insulating substrate 117 by such means as vapor deposition or etching. The insulating substrate 117 is inserted and guided to a guide groove 112b provided in the central longitudinal direction of a top board 112a attached to the upper surface inside a shield plate 112, and is attached by making an end part 113a inserted in the recessed part 115a of a side part member 115 which is attached to both ends of the plate 112 by means of a resin screw. A control grid 116 is attached to an aperture part on the lower side of the plate 112. When the board 70 is exchanged, the member 115 on one side can be detached from the plate 112 and the board 117 can be pulled out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, and more particularly, to a corona discharge device for charging a surface of an image carrier, the corona discharge having a plurality of pointed discharge electrode plates. Regarding the device.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an image by an electrophotographic method, a photosensitive drum is uniformly charged by a corona discharge type charger and then imagewise exposed by an image exposing device to form a latent image. Then, after developing with a developing device to form a toner image, the toner image is transferred onto a transfer sheet, which is a transfer material, by a transfer device.

Conventionally, corona discharge type chargers used in this type of image forming apparatus are classified into a wire discharge type (corotron, scorotron, dicorotron, etc.) and a pin discharge type (pin electrode type, serrated electrode type, etc.). Broadly divided. The latter pin discharge method has come to be used in electrophotographic copying machines, printers and the like in recent years because of low ozone generation. In particular, an integrated sawtooth electrode having a structure in which a plurality of sawtooth discharge electrode portions are provided on one thin plate member is easy to miniaturize,
It is characterized by low ozone generation and low discharge voltage. And, the charger using the sawtooth discharge electrode is
JP-A-63-15272 and U.S. Pat. S. P. 4725
The technique is disclosed by the specification, etc.

As a corona charger using a sawtooth electrode, a charger as shown in FIG. 1 is used. FIG.
FIG. 1A is a front view showing the configuration of a corona charger, and FIG.
1B is a cross-sectional view taken along the line AA of the corona charger shown in FIG.

In FIG. 1, 111 is a photosensitive drum 10.
The saw-tooth electrode for corona discharge located toward the side, and 112 is a shield plate having an opening having a U-shaped cross section. The sawtooth electrode 111 is an insulating electrode plate holding member 1.
It is attached to the shield plate 112 by 13 and the pressing member 114.

In addition, the corona charger of the independent sawtooth electrode in which a high voltage is applied to each of the sawtooth discharge electrodes via a resistor is
Compared with the corona charger of the sawtooth electrode described above, the amount of ozone generated is further reduced, and the variation in the discharge current of each independent sawtooth electrode is reduced.

[0007]

A corona discharge device using a corona charger has a wire electrode and mainly a sawtooth electrode, but the corona discharge device using a sawtooth electrode is easy to miniaturize as described above. The features are that the amount of ozone generated is small and the discharge voltage is low. Further, the independent sawtooth electrode has the features that the amount of ozone generated is further reduced and the variation of the discharge current of each independent sawtooth electrode is reduced as compared with the normal sawtooth electrode. However, since the tips of the integrated sawtooth electrode and the independent sawtooth electrode are sharp and long and protrude, the handling is troublesome, the tip is easily deformed, and there is a concern that the operator's hand or finger may be damaged.

Further, when the corona discharge device is used for a long time, foreign matters such as toner and paper dust generated in the periphery adhere to the discharge electrode, which causes charging failure and image failure. Even if the discharge electrode is cleaned and used, the frequency of replacement of the discharge electrode increases.

The present invention has been made to solve the above problems. That is, it provides a corona discharge device which is easy to handle, easy to assemble and maintain without damaging the operator's hands and fingers, the discharge electrodes can be easily replaced, and the ozone discharge amount is small. This is the purpose.

[0010]

The object of the present invention is achieved by adopting the following constitution.

A corona discharge electrode in which a plurality of discharge electrodes are linearly formed on an insulating substrate, and a control grid located between the corona discharge electrode and the image carrier to control the surface potential of the image carrier. In the corona discharge device having, the corona discharge electrode is in close contact with the insulating substrate, the tip of the corona discharge electrode facing the image carrier is provided at a position not protruding from the tip of the insulating substrate. The corona discharge device is replaceable with the corona discharge device.

In the above invention, the corona discharge device is arranged in the circumferential direction of the rotating image carrier.
An image forming unit including an image exposure device and a developing device for forming a plurality of toner images, a transfer device, and a cleaning device are provided to charge the peripheral surface of the image carrier while the image carrier rotates once.
In a preferred form, it is mounted in a color image forming apparatus that forms a color toner image by superimposing toner images of different colors by repeating image exposure and development, and transfers the color toner image to a transfer material by a transfer device. is there.

Further, in the above invention, the corona discharge device may be arranged in a circumferential direction of a rotating image carrier.
An image forming unit for forming a plurality of toner images including an image exposure device and a plurality of developing devices, a transfer device, and a cleaning device are provided, and the peripheral surface of the image carrier is rotated while the image carrier rotates a plurality of times. It may be mounted in a color image forming apparatus that forms a color toner image by superimposing toner images of different colors by repeating charging, image exposure, and development, and transfers the color toner image to a transfer material by a transfer device. This is the preferred form.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings and FIGS.

FIG. 2 is a block diagram showing an example of a color image forming apparatus equipped with the corona discharge device of the present invention.

In FIG. 2, reference numeral 10 denotes a photosensitive drum, which is a drum-shaped image bearing member (hereinafter referred to as a photosensitive drum), and is provided on the outer periphery of a cylindrical substrate formed of a transparent member such as optical glass or transparent acrylic resin. A transparent conductive layer, an organic photoreceptor (OPC), and a photosensitive layer composed of a-Si are provided.

The photosensitive drum 10 is bearing-supported by a flange guide pin at one end, and the flange at the other end is externally fitted to a plurality of guide rollers provided on the substrate of the main body of the apparatus to drive gears on the outer circumference. , And is rotated clockwise with the driving force thereof grounding the transparent conductive layer.

Reference numerals 11Y, 11M, 11C, and 11K are corona chargers used in the image forming process of each color of yellow (Y), magenta (M), cyan (C), and black (K), and are provided on the photosensitive drum 10. The above-mentioned organic photoreceptor layer is charged by the grid held at a predetermined potential and the corona discharge by the electrode plate to give a uniform potential to the photoreceptor drum 10.

12Y, 12M, 12C and 12K are LEDs, FL, EL, arranged in the axial direction of the photosensitive drum 10.
An exposure optical system including a light emitting element such as a PL and an image forming element such as a SELFOC lens, in which image signals of respective colors read by a separate image reading device are sequentially taken out from a memory and each of the exposure optical systems described above. System 12Y, 12M, 12
The electric signals are input to C and 12K, respectively.

Each of the above-mentioned exposure optical systems 12Y, 12M, 12
Both C and 12K are attached to a cylindrical support member 120 fixed to the substrate of the apparatus main body with guide pins as guides, and are housed inside the base body of the photosensitive drum 10. The exposure optical system 12 includes an LCD, LIS and
A combination of optical shutter members such as A and PLZT and an imaging element such as a SELFOC lens can also be used.

13Y, 13M, 13C and 13K are developing units which are developing means for accommodating yellow (Y), magenta (M), cyan (C) and black (K) developers, respectively.
The developing sleeves 130 rotate in the same direction while maintaining a predetermined gap with respect to the peripheral surface of the photoconductor drum 10.

The developing devices 13Y, 13M, 13C and 13K are the corona chargers 11Y, 11M and 1 described above.
Charging by 1C and 11K, exposure optical system 12Y, 12
The electrostatic latent image formed on the photosensitive drum 10 by image exposure with M, 12C, and 12K is subjected to reversal development by a non-contact development method under application of a development bias voltage.

The image of the original is read by an image reading device separate from the present device, and the image read by the image pickup device or the image edited by the computer is once used as an image signal for each color of Y, M, C and K. Stored and stored in memory.

In forming an image, the photoconductor drum 1 is started by starting the photoconductor drive motor by starting the image recording.
0 is rotated clockwise, and at the same time, application of electric potential to the photoconductor drum 10 is started by the charging action of the corona charger 11Y.

After a potential is applied to the photosensitive layer of the photosensitive drum 10, the exposure optical system 12Y starts image exposure with an electric signal corresponding to a first color signal, that is, a yellow (Y) image signal. By rotating and scanning the drum, an electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface of the drum.

The latent image is reversal-developed by the developing device 13Y with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further given a potential on the yellow (Y) toner image by the discharge action of the corona charger 11M, and the second color signal of the exposure optical system 12M, that is, magenta (M). Image exposure is performed by an electric signal corresponding to the image signal, and a magenta (M) toner image is formed on the yellow (Y) toner image by non-contact reversal development by the developing device 13M. It

By the same process, the corona charger 11
C, the exposure optical system 12C, and the developing device 13C further produce a cyan (C) toner image corresponding to the third color signal, and finally, the corona charger 11K and the exposure optical system 12K.
A black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed by the developing device 13K, and a color toner image is formed on the peripheral surface of the photosensitive drum 10 within one rotation. .

These exposure optical systems 12 (Y, M, C,
Image exposure of the photosensitive layer of the photoconductor drum 10 by K) is performed from the inside of the drum through the transparent substrate. Therefore, the exposure of the images corresponding to the second, third, and fourth color signals is performed in a state in which none of the toner images previously formed is transmitted, and the image corresponding to the first color signal is exposed. It is possible to form an equivalent electrostatic latent image.

Each exposure optical system 12 (Y, M, C,
In order to stabilize the temperature inside the photosensitive drum 10 and prevent the temperature rise due to the heat generation of K), a material having good thermal conductivity is used for the supporting member 120, a heater is used at low temperature, and heat is used at high temperature. By taking measures such as radiating heat to the outside through the pipe, it can be suppressed to the extent that there is no problem. Further, during the developing action by each developing device, a developing bias voltage in which a direct current or an alternating current is applied to the developing sleeve is applied respectively, and jumping development is performed by the one-component or two-component developer accommodated in the developing device, thereby making it transparent. Non-contact reversal development is performed on the photoconductor drum 10 whose grounding is the conductive layer.

The photosensitive drum 10 and the corona charger 1 described above.
1 (Y, M, C, K), exposure optical system 12 (Y, M, C,
K), the developing device 13 (Y, M, C, K) and the cleaning device 19 are housed in a detachable housing inside the image forming apparatus main body to form the process cartridge 100.

The color toner image thus formed on the peripheral surface of the photosensitive drum 10 is conveyed from the paper feeding cassette 15 in the corona transfer device 14A having a transfer electrode and is fed in synchronization with the driving of the timing roller 16. Is transferred onto a transfer paper which is a transfer material.

The transfer paper on which the toner image has been transferred is separated from the peripheral surface of the photosensitive drum 10 by removing the charge in the corona charge-eliminating separator 14B having a separating electrode, and the toner image is fused in the fixing device 17. Later paper ejection roller 1
It is discharged onto the tray 20 at the upper part of the apparatus via the unit 8.

Hereinafter, the corona charger 11 (Y, M,
C, K), corona transfer device 14A, corona charge removal separator 14
B is generically called a corona discharge device.

On the other hand, the photosensitive drum 10 from which the transfer paper is separated
The cleaning device 19 removes and cleans the residual toner to continue forming the toner image of the original image, or temporarily stops and waits for the formation of a new toner image of the original image.

FIG. 3 is an enlarged sectional view showing a part of the image forming apparatus of FIG. A plurality of developing devices 13Y, 13M,
13C shows a plurality of corona chargers 11Y, 11M, 11C and 11K arranged adjacent to 13C and 13K. Since these corona chargers 11Y, 11M, 11C, and 11K have the same structure, the corona chargers will be hereinafter referred to as the corona charger 11 as a representative.

FIG. 4 is a front view of the corona charger 11.

3 and 4, reference numeral 111 denotes a sawtooth electrode which is an example of a corona discharge electrode, which will be described in detail with reference to FIG. 112
Is a shield plate having an opening, and the photosensitive drum 1
An opening is provided substantially parallel to the 0 circumferential surface. The shield plate 112 is, for example, a stainless steel shield plate.

The sawtooth electrode 111 is attached to an electrode plate holding member 113 made of an insulating resin, and is pressed by a pressing member 114 also made of an insulating resin, and then both ends are made of an insulating resin, for example, ABS resin. It is sandwiched by the front and rear side members 115, dropped into the shield plate 112, and the electrode plate holding member 113 having the sawtooth electrode 111, the pressing member 114, and the side member 115 are integrally fixed to the shield plate 112 by a resin screw.

On the opening side of the shield plate 112,
For example, a control grid 116, which is a control electrode formed by etching a stainless steel plate having a thickness of 0.1 mm to have a mesh width of 1 mm, is attached to the side member 115 with a resin screw for attaching the control grid, and a scorotron-type corona charging is performed. The vessel 11 is assembled.

The width of the opening generally affects the charging performance, and the wider the opening, the better the charging performance. The slower the linear velocity (peripheral velocity) of the photosensitive drum 10, the more advantageous for charging. Although the width of the opening is determined depending on the image forming apparatus, in the image forming apparatus having the corona charger of the present invention, the peripheral space of the photoconductor drum 10 is effectively used and the image processing unit such as the image exposure device or the developing device is used. The corona chargers 11Y, 11M, 11C, and 11K have a narrow and flat configuration in order to properly arrange the above-mentioned components and obtain a small-sized image forming apparatus which has not been available in the past. However, for this reason, the interval between the shield plates 112 becomes narrow, and an excessive overcurrent flows from the saw-tooth electrode 111 to the side plate of the shield plate 112 and the control grid 116, which causes a problem that proper and uniform charging characteristics cannot be obtained. .

The present invention is intended to obtain proper and uniform charging characteristics even for such a narrow and flat corona discharge device.

FIG. 5A shows a sawtooth electrode 111 according to the present invention.
5 is a perspective view of a sawtooth electrode plate 70 including the insulating substrate 117 and FIG. 5B is a side sectional view of the sawtooth electrode plate 70.
(C) is a front view of the sawtooth electrode plate 70.

In FIG. 5, the saw-tooth electrode plate 70 provided on the corona charger 11 has the saw-tooth electrode 111 on which the insulating substrate 1 is formed.
It is integrally formed on 17 by means such as vapor deposition or etching. Alternatively, the sawtooth electrode 111 made of a conductive thin plate such as a stainless steel plate is attached to the insulating substrate 117.
It is formed by closely adhering to and joining.

The tip portions of a plurality of equal-length electrode tips 111a, which are linearly arranged at a constant pitch, are located opposite to the circumferential surface of the photosensitive drum 10. Sawtooth electrode plate 70
The sawtooth electrode 111 has a point p of the tip 111a of 2 m.
m, the height h of the peak is 2 mm, the apex angle θ of the peak is 15 °, and the tip radius r of the peak is 20 μm or less. Adjacent peaks 11 of the sawtooth electrodes 111
If the pitch p between 1a and 111a is too close, a discharge current will flow and the discharge will become unstable. Therefore, the pitch p requires a certain distance. As a result of various studies, this pitch p is 2
mm or more is necessary for discharge stabilization. Sawtooth electrode 11
1 is connected to a power supply 110 that applies a high voltage of 4 to 10 kV.

The pointed portion 111 a of the sawtooth electrode 111 facing the control grid 116 is formed on the insulating substrate 11.
7 are arranged in parallel with each other at a position slightly retracted from the front end portion 117a. The insulating substrate 117 is a ceramic plate,
It is made of a material such as a glass plate or an epoxy resin plate that does not cause dielectric breakdown even when a high voltage is applied.

The point 11 of the sawtooth electrode 111 is formed on the surface of the sawtooth electrode plate 70 opposite to the insulating substrate 117.
The part other than 1a may be covered with the insulating covering member 118. The insulating substrate 117, the sawtooth electrode 111,
By arranging the insulating coating member 118 in this way, the pointed portion 111a of the sawtooth electrode 111 that facilitates handling at the time of maintenance, inspection, and repair of the corona charger without damaging the operator's hands or fingers. Since it is less likely to become dirty, it is possible to obtain a stable discharge performance for a long time, the corona charger 11 can be downsized, and other effects.

FIG. 6 is a front view of a discharge electrode section in which a plurality of independent sawtooth electrodes are arranged.

In FIG. 6, a plurality of independent sawtooth electrodes 119 are provided.
Are arranged in parallel on the insulative substrate 117, and are covered with an insulative covering member 118 except the pointed head 119a which is the discharge acting portion of the independent sawtooth electrode 119. Each of the plurality of independent sawtooth electrodes 119 has an electric resistance R.
It is connected to the power source 110 via. The pointed heads 119a of the plurality of independent sawtooth electrodes 119 facing the control grid 116 are arranged in parallel with each other at a position slightly retracted from the tip end 117a of the insulating substrate 117.

By connecting each of the independent sawtooth electrodes 119 with the sawtooth electrode as an independent sawtooth electrode to the power source 110 through the electric resistance R, the corona charger further reduces the amount of ozone generated. Dispersion of the discharge current of each independent sawtooth electrode 119 is reduced, and a stable and uniform charging characteristic is obtained.

FIG. 7 is a perspective view showing an embodiment of a corona charger according to the present invention.

In FIG. 7, the corona charger 11 has substantially the same structure as the charger described with reference to FIGS.
The insulating substrate 117 of the sawtooth electrode plate 70 is inserted and guided in the guide groove 112b provided in the central longitudinal direction of the top plate 112a attached to the inner upper surface of the shield plate 112, and attached to both ends of the shield plate 112 with resin screws. The insulating substrate 1 is provided in the recess 115a of the side member 115.
17 are attached by inserting the end portions 113a of both end portions. The control grid 116 is attached to the lower opening of the shield plate 112 by a resin screw (not shown).

The present corona charger 11 configured as described above
When replacing the sawtooth electrode plate 70, by removing the resin screw of the side member 115 on one side and removing it from the shield plate 112, the end portion 113a of the insulating substrate 117 of the sawtooth electrode plate 70 is moved to the opposite side. Recess 115 of side member 115
It can be removed from the shield plate 112 by removing it from a. Next, the end portion 113a of the insulating substrate 117 of the new sawtooth electrode plate 70 is connected to the guide groove 112 of the top plate 112a.
After inserting into the recess 115a of the side member 115 via b, insert the end 113a of the insulating substrate 117 of the sawtooth electrode plate into the recess 115a of the removed side member 115,
The side member 115 is attached to the shield plate 11 with a resin screw.
You can attach it to 2.

Thus, the saw-tooth electrode plate 70, which is the corona discharge electrode of the corona charger 11, can be easily replaced.

FIG. 8 is a view showing a corona charger of the type in which the saw-tooth electrode is vertically attached and detached.

In FIG. 8, a sawtooth electrode plate 70 having an insulating substrate 117 on which the sawtooth electrode 111 is provided as described above.
Are attached to the electrode plate holding member 113 with resin screws not shown, and the electrode plate holding member 113 is attached to the inner upper surface of the shield plate 112 with resin screws. The control grid 116 is attached to the lower opening of the shield plate 112 by a resin screw (not shown).

The present corona charger 11 configured as described above
When replacing the sawtooth electrode plate 70, the control grid 1
16 is removed by removing a resin screw (not shown), and the resin screw on the upper surface of the shield plate 112 is removed to remove the sawtooth electrode plate 70.
The electrode plate holding member 113 to which is attached is removed. The sawtooth electrode plate 70 can be removed by removing a resin screw (not shown) from the electrode plate holding member 113. Next, a new sawtooth electrode plate 70 is attached to the electrode plate holding member 113 with a resin screw (not shown), and the electrode plate holding member 113 is attached to the inner upper surface of the shield plate 112 with a resin screw. The replacement is completed by attaching the control grid 116 to the lower opening of the shield plate 112 with a resin screw (not shown).

FIG. 9 is a view showing a corona charger of the type in which sawtooth electrodes are attached / removed in the left / right direction.

In FIG. 9, in this method, the shield plates are left and right shield plates 112a, 112b.
The shield plate 112 is separated as shown in FIG.
The a and 112b are attached to the electrode plate holding member 113 from the left and right by resin screws. Control grid 11
6 is also attached to the lower openings of the shield plates 112a and 112b from the left and right by resin screws. Therefore, when exchanging the sawtooth electrode plate 70, these resin screws are removed and the shield plate 112b or 11 is removed.
2a is removed from the electrode plate holding member 113, the control grid 116 is removed from the shield plate 112a or 112b which is not removed from the electrode plate holding member 113, the sawtooth electrode plate 70 is removed from the electrode plate holding member 113, and a resin screw (not shown) is used. Remove and remove. When a new sawtooth electrode plate 70 is attached, the procedure described above may be reversed, as is the case with FIG.

As described above, the sawtooth electrode plate 70, which is the corona discharge electrode of the corona charger 11, can be easily replaced, as can be seen from the description of FIGS. 8 and 9.

As described above, since the saw-tooth electrode of the corona charger can be easily replaced, there is an effect that assembly and maintenance can be facilitated.

The corona discharge device of the present invention described above is not limited to the corona charger 11 described above, but can be applied to the corona transfer device 14A and the corona charge removal separator 14B.

FIG. 10 is a block diagram showing another embodiment of the image forming apparatus having the corona discharge device of the present invention.
In the figure, parts having the same functions as in FIG. 2 of the above-described embodiment are assigned the same reference numerals. Therefore, the points different from the above embodiment will be described below.

Reference numeral 101 denotes a belt-shaped image bearing member, a so-called photosensitive belt, which is formed by coating an organic photosensitive layer (OPC) on the outer circumference of a flexible endless substrate, and which is arranged in a horizontal direction between the rotary roller. In the state of being stretched around, it is circulated and conveyed in the clockwise direction in the drawing by the drive of the rotating roller. The photoconductor belt 101 forms an image forming surface by rubbing the lower peripheral surface of the photoconductor belt 101 against the guide member 102 by the bias of a tension roller.

11Y, 11M, 11C and 11K are scorotron charging type corona chargers.
The above-mentioned organic photosensitive layer is charged by a corona discharge by a control grid and a sawtooth electrode held at a predetermined potential to give a uniform potential to the photosensitive belt 101.

12Y, 12M, 12C, and 12K are LEDs, FL, EL, PL in which light emitting elements are arranged in a line in the depth direction of the photosensitive belt 101, or LCD, LISA, in which elements having an optical shutter function are arranged in parallel. An exposure optical system composed of a PLZT and a SELFOC lens as a unity-magnification imaging element, in which image signals of respective colors read by a separate image reading device are sequentially taken out from a memory to the exposure optical systems. Each is input as an electric signal.

Reference numerals 13Y, 13M, 13C and 13K denote developing units for accommodating yellow (Y), magenta (M), cyan (C) and black (K) developers, respectively. On the other hand, a developing sleeve is provided which rotates in the same direction while maintaining a predetermined gap. Each developing device 13
(Y, M, C, K) is the corona charger 11 described above.
(Y, M, C, K) charging and exposure optical system 12 (Y,
The electrostatic latent image formed on the photosensitive belt 101 by image exposure with M, C, K) is reversely developed in a non-contact state by applying a developing bias voltage.

In the color image forming apparatus described above, the corona charger 11, the exposure optical system 12, and the developing device 13 constitute one set of a single color, and four sets of these sets are arranged in series. The present invention is of course applicable to the corona charger 11, the corona transfer device 14A, and the corona charge removal separator 14B, which are the corona discharge devices mounted on the image forming apparatus.

FIG. 11 is a constitutional view showing still another embodiment of the image forming apparatus having the corona discharge device of the present invention. In the figure, parts having the same functions as in FIG. 2 of the above-described embodiment are assigned the same reference numerals. Therefore, the points different from the above embodiment will be described below.

The image forming apparatus comprises a rotating image carrier 10
In the circumferential direction, an image forming unit including a corona charger 11, an image exposure unit 12, a plurality of developing units 13Y, 13M, 13C, and 13K, a corona transfer unit 14A, and a corona charge removal separator 1
4B and the cleaning device 19 are provided, and the image carrier 1
During a plurality of rotations of 0, the peripheral surface of the image carrier 10 is repeatedly charged, image-exposed and developed to form toner images of different colors, thereby forming a color toner image. The color toner image is transferred to the corona transfer device 14A. Transfer to the transfer material by
After the transfer material is separated from the image carrier 10 by the corona charge-eliminating separator 14B, the transfer material is heat-fixed by the fixing device 17 and discharged onto the tray 20 above the apparatus via the paper discharge roller 18. The present invention is of course applicable to the corona charger 11, the corona transfer device 14A, and the corona charge removal separator 14B, which are the corona discharge devices mounted on the image forming apparatus.

[0071]

According to the invention of claim 1, the corona charger can be easily handled during assembly, maintenance, inspection and repair without damaging the operator's hands or fingers, and the discharge electrode can be easily replaced. Has the effect that can be done.

The structure of the invention according to claim 2 has an effect that the corona charger can be downsized and the amount of ozone generated is reduced.

The configurations of the inventions according to claims 3 and 4 have the effects that the amount of ozone generated is further reduced, the variation in discharge current is reduced, and stable and uniform charging characteristics are obtained.

According to the fifth and sixth aspects of the invention, a color image is formed by a method of forming a color image by rotating the image carrier once or by a method of forming a color image by rotating the image carrier a plurality of times. It is possible to provide a corona discharge electrode of a color image forming apparatus capable of achieving the above.

As described above, according to the present invention, the handling is good, the assembling and maintenance are easy without damaging the hands and fingers of the operator, the discharge electrode can be easily replaced, and the ozone generation amount is small. It has become possible to provide a corona discharge device with a small number of charges.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a corona discharge device having a conventional sawtooth electrode.

FIG. 2 is a configuration diagram of an image forming apparatus having a corona discharge device of the present invention.

3 is a partially enlarged cross-sectional view of the image forming apparatus shown in FIG.

FIG. 4 is a front view of the corona charger shown in FIG.

FIG. 5 is a diagram showing an embodiment of a sawtooth electrode of a corona charger according to the present invention.

FIG. 6 is a front view showing an embodiment of an independent sawtooth electrode according to the present invention.

FIG. 7 is a perspective view showing an embodiment of a corona charger according to the present invention.

FIG. 8 is a diagram showing another embodiment of the corona charger shown in FIG.

FIG. 9 is a view showing still another embodiment of the corona charger shown in FIG.

FIG. 10 is a configuration diagram showing another embodiment of an image forming apparatus including the corona discharge device of the present invention.

FIG. 11 is a configuration diagram showing still another embodiment of an image forming apparatus including a corona discharge device of the present invention.

[Explanation of symbols]

 10 Photoconductor Drum (Image Carrier) 100 Process Cartridge 101 Photoconductor Belt (Image Carrier) 11, 11Y, 11M, 11C, 11K Corona Charger 111 Sawtooth Electrode (Corona Discharge Electrode) 111a, 119a Tip 112 Shield Plate 113 Electrode Plate Holding Member 114 Controlling Member 116 Control Grid 117 Insulating Substrate 118 Insulating Covering Member 119 Independent Sawtooth Electrode (Corona Discharge Electrode) 12Y, 12M, 12C, 12K Exposure Optical System 13Y, 13M, 13C, 13K Developing Device 14A Corona Transfer device 14B Corona static eliminator 70 Sawtooth electrode

Front page continued (72) Inventor Hiroyuki Tokimatsu 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Satoshi Haneda 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company

Claims (6)

[Claims] 1. A corona discharge electrode in which a plurality of discharge electrodes are linearly formed on an insulating substrate, and a control located between the corona discharge electrode and the image carrier to control the surface potential of the image carrier. In a corona discharge device having a grid, the corona discharge electrode is in close contact with an insulating substrate, the tip of the corona discharge electrode facing the image carrier is provided at a position not protruding from the tip of the insulating substrate. The corona discharge electrode is replaceable with the corona discharge device. 2. The corona discharge device according to claim 1, wherein the corona discharge electrode is a sawtooth electrode plate integrally formed by linearly arranging a plurality of sawtooth-shaped cusps. 3. The corona discharge electrode according to claim 1, wherein the corona discharge electrode is a corona discharge electrode formed by arranging a plurality of independent discharge electrodes each having a serrated point in a straight line. Corona discharge device. 4. The corona discharge device according to claim 3, wherein the plurality of independent discharge electrodes are individually connected to a common power source to which a high voltage is applied via electric resistance. 5. The corona discharge device comprises an image forming means for forming a plurality of toner images, which comprises a corona discharge device, an image exposure device and a developing device, in the circumferential direction of a rotating image carrier, a transfer device and a cleaning device. The color toner image is formed by superposing different color toner images by repeating charging, image exposure and development on the peripheral surface of the image carrier while the image carrier is rotated once. The corona discharge device according to claim 1, wherein the corona discharge device is mounted on a color image forming device that transfers an image onto a transfer material by a transfer device. 6. The corona discharge device comprises an image forming means, a transfer device and a cleaning device for forming a plurality of toner images, each of which comprises a corona discharge device, an image exposure device and a plurality of developing devices in the circumferential direction of a rotating image carrier. Are provided, and while the image carrier rotates a plurality of times, charging, image exposure, and development are repeated on the peripheral surface of the image carrier to form a color toner image by superimposing toner images of different colors. The corona discharge device according to claim 1, wherein the corona discharge device is mounted on a color image forming device that transfers the color toner image onto a transfer material by a transfer device.