JPH09114194A - Corona discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corona discharge device using an integral discharge electrode and an independent serrate electrode type discharge electrode, having a stable discharge characteristic and uniform electrification at a low cost, capable of easily cleaning the discharge electrode, having a sufficient discharge with a smaller discharge current and a good handling property, and easy to assemble and maintain. SOLUTION: This corona discharge device is provided with a corona discharge electrode 111 linearly formed with multiple discharge electrodes, a control grid 116 located between the corona discharge electrodes and an image carrier 10 and controlling the surface potential of the image carrier 10, and plate-like shield plates 112 located on both sides of the corona discharge electrodes. The corona discharge electrodes are multiple electrode plates held on multiple insulating substrates 1117A, 117B arranged in parallel respectively in this corona discharge device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona discharge device for charging the surface of a photoconductor (image forming body) in electrophotographic image formation, and more particularly to a non-contact type of a plurality of point-shaped corona discharge devices. The present invention relates to a corona discharge device having a discharge electrode.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an image by an electrophotographic method, a photosensitive member is uniformly charged by a corona discharge type charger, and then imagewise exposed by an imagewise exposing means to form a latent image. Then, after being developed by the developing means to form a toner image, the toner image is transferred onto the recording paper by the transfer device.

Conventionally, corona discharge type chargers used in this type of image forming apparatus are largely classified into a wire discharge type (corotron, scorotron, dicorotron, etc.) and a pin discharge type (pin electrode type, serrated electrode type, etc.). Be separated. The latter has recently come to be used in electrophotographic copying machines, printers and the like due to low ozone generation. In particular, a sawtooth electrode having a structure in which an electrode plate in which a plurality of sawtooth electrode portions are provided on one thin plate member is easy to miniaturize, generates a small amount of ozone, has a low discharge voltage, etc. There is a feature of. A charger using a sawtooth discharge electrode is disclosed in Japanese Patent Laid-Open No. 63-15272.
JP-A-5-45999 and U.S. Pat. S. P.
No. 3,691,373.

As a corona charger using a sawtooth electrode, a charger as shown in FIG. 16 is used. FIG. 16A is a front view showing the configuration of the corona charger.
6 (B) is AA of the corona charger shown in FIG. 16 (A).
FIG. In these figures, 111 is a saw-tooth electrode for corona discharge located toward the photoconductor drum 10, and 112 is a shield plate having an opening having a U-shaped cross section. The sawtooth electrode 111 is attached to the shield plate 112 by an insulating electrode plate holding member 113 and a pressing member 114, and the external shape is a hexahedron having a rectangular cross section.

Further, the independent saw-tooth electrode type corona charger in which a high voltage is applied to each of the saw-tooth discharge electrodes produces a smaller amount of ozone as compared with the above-mentioned saw-tooth electrode type corona charger. The feature is that the variation of the discharge current of each sawtooth electrode portion is reduced.

[0006]

At present, image forming apparatuses are required to be downsized and to be processed at high speed.
In order to meet this requirement, the photosensitive drum is a small-diameter drum, and the processing means such as the corona charger, the image exposure means, and the developing means arranged in the peripheral portion are downsized, and the interval between the processing means is narrowed. It is necessary. In particular, a plurality of sets of corona chargers, image exposing means and developing means are provided on the peripheral portion of the photoconductor drum, and a plurality of toner images are formed on the photoconductor by superimposing them, and the formed multicolor toner images are collectively formed. In an image forming apparatus for transferring the image onto a recording sheet, it is strongly desired to reduce the size of the above-mentioned processing means and reduce the interval between the processing means because the number of processing means provided in the peripheral portion of the photosensitive drum is large. .

The corona discharge device has a wire electrode and a sawtooth electrode. The corona discharge device using the sawtooth electrode is characterized in that it can be easily downsized, the amount of ozone generated is small, and the discharge voltage is low. In addition, the independent sawtooth electrode produces a smaller amount of ozone compared to the normal sawtooth electrode,
The feature is that the variation of the discharge current of each independent sawtooth electrode is reduced. However, since the tips of the sawtooth electrode and the independent sawtooth electrode are sharp and protrude long, there are disadvantages that they are troublesome to handle, and the tips are easily soiled and difficult to clean.

The present invention has been made to solve the above-mentioned problems, and in a corona discharge device using an integrated discharge electrode and an independent sawtooth electrode type discharge electrode, discharge characteristics are stable and uniform charging is performed. It is possible to supply a corona discharge device at a low cost, to make the discharge electrode resistant to dirt, to easily clean the discharge electrode, to perform sufficient discharge with a smaller discharge current, to make it easy to assemble and to handle. It is an object of the present invention to provide a corona discharge device having features such as easy maintenance.

[0009]

The above object is to provide a corona discharge electrode formed by linearly forming a plurality of discharge electrodes on an insulating substrate, and to locate the image between the corona discharge electrode and the image carrier. In a corona discharge device having a control grid for controlling the surface potential of a carrier and plate-shaped shield plates located on both sides of the corona discharge electrode, the corona discharge electrodes are a plurality of insulating substrates arranged in parallel. It is achieved by a corona discharge device characterized in that it has a plurality of electrodes respectively held on the.

Another object of the present invention is to provide a corona discharge electrode in which a plurality of discharge electrodes are linearly formed on an insulating substrate and a surface potential of the image carrier located between the corona discharge electrode and the image carrier. In a corona discharge device having a control grid for controlling, and a plate-shaped shield plate located on both sides of the corona discharge electrode, the corona discharge electrode is a plurality of electrodes formed on both sides of the insulating substrate. It is achieved by a corona discharge device characterized in that

In the above-mentioned invention, the corona discharge device is arranged in the circumferential direction of the rotating image carrier,
Four sets of image forming means including an image exposure means and a developing device, a transfer means, and a cleaning device are provided to charge, image expose, and charge the peripheral surface of the image carrier during one rotation of the image carrier. A preferable mode is that the toner images of different colors are superposed by repeating the development to form a color toner image, and the color toner image is transferred to a transfer material by a transfer means.

Further, in the above invention, the corona discharge device includes an image forming means including a corona discharge device, an image exposure means, and a plurality of developing devices, a transfer means, and a cleaning device in a circumferential direction of a rotating image carrier. And a plurality of different color toner images are formed by repeating charging, image exposure and development on the peripheral surface of the image carrier while the image carrier is rotated a plurality of times. In a preferred embodiment, the color toner image is mounted on a color image forming apparatus that transfers the color toner image onto a transfer material by a transfer unit.

[0013]

1 is a block diagram showing an example of a color image forming apparatus suitably equipped with a corona discharge device of the present invention. In the figure, reference numeral 10 denotes a drum-shaped image bearing member, that is, a photosensitive drum, and a transparent conductive layer, an organic photosensitive member (OPC) or a on the outer periphery of a cylindrical substrate formed of a transparent member such as optical glass or transparent acrylic resin. A photosensitive layer made of —Si or the like is 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 the outer peripheral gear as a drive gear. , 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). 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 columnar support member 12A fixed with a guide pin as a guide with respect to the substrate of the apparatus main body, and housed inside the base of the photosensitive drum 10. The exposure optical system 12 includes an LCD, LIS and the above light emitting element.
A combination of optical shutter members such as A and PLZT and an imaging element such as a SELFOC lens can also be used.

13 (Y), 13 (M), 13 (C) and 13 (K) are development containing yellow (Y), magenta (M), cyan (C) and black (K) developers. In the developing device, which is a means, a developing sleeve 13 that rotates in the same direction with a predetermined gap with respect to the peripheral surface of the photosensitive drum 10, respectively.
0 is provided.

The developing devices 13Y, 13M, 13C and 13K are the corona chargers 11Y, 11M and 1 described above.
1C and 11K charging and exposure optical systems 12Y and 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 which is separate from this 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, and the drum is started. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface by the rotational scanning of.

The latent image is reversely developed by the developing device 13Y in a state where the developer on the developing sleeve is not in contact with the latent image, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photoconductor 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 image of the exposure optical system 12M.
Image signal is applied by an electric signal corresponding to the color signal of (1), that is, the image signal of magenta (M), and the non-contact reversal development by the developing device 13M causes the magenta (M) toner image on the yellow (Y) toner image. The toner images are sequentially superposed and formed.

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,
Finally, a black (K) toner image corresponding to the fourth color signal is sequentially formed by the corona charger 11K, the exposure optical system 12K, and the developer 13K, and the black (K) toner image is formed within one rotation of the photosensitive drum 10. A color toner image is formed on the peripheral surface.

Image exposure on the photosensitive layer of the photosensitive drum 10 by each of these exposure optical systems 12 (Y to K) is performed from the inside of the drum through the transparent substrate. Therefore, the exposure of the image 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 is equivalent to the image corresponding to the first color signal. It is possible to form an electrostatic latent image of. Each exposure optical system 12
In order to stabilize the temperature inside the photoconductor drum 10 and prevent the temperature rise due to the heat generation of (Y to K), a material having good thermal conductivity is used for the support member 101, and a heater is used when the temperature is low.
When the temperature is high, it can be suppressed to such an extent that there is no problem by taking measures such as radiating heat to the outside through a heat pipe. 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 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 photoconductor drum by removing the charge in the corona charge-eliminating separator 14B having a separation electrode, and is fixed by the fixing device 17.
After the toner is welded, the toner is discharged onto the tray 20 at the upper part of the apparatus through the paper discharge roller 18.

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 residual toner to continue forming the toner image of the original image, or temporarily stops and waits for formation of a new toner image of the original image.

FIG. 2 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. 3 is a side view of the corona charger 11.

In FIGS. 2 and 3, reference numeral 111 denotes a saw-tooth electrode which is an example of a corona discharge electrode, and a tip portion in which a plurality of pointed head portions 111a, which are electrode tips of equal length, are linearly arranged at a constant pitch is a photosensitive drum. It is located opposite to the circumferential surface of 10. The sawtooth electrode 111 is made by etching a stainless steel plate having a thickness of 0.05 mm,
1a has a pitch p of 2 mm, a peak height h of 2 mm, a peak apex angle θ of 15 °, and a peak radius r of 20 μm or less (see FIG. 7).

Reference numeral 112 denotes a shield plate having an opening, and the opening is provided substantially parallel to the circumferential surface of the photosensitive drum 10. 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 electrode (grid) made to have a mesh width of 1 mm by etching a 0.1 mm thick stainless steel plate.
The 116 is attached to the side member 115 with a resin screw for attaching the control electrode, and the scorotron type corona charger 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. For this reason, the charging performance is deteriorated, and in order to obtain proper and uniform charging characteristics, a high voltage has to be applied, which causes a problem that the ozone generation amount increases. Further, since the discharge part of the sawtooth electrode is limited to the tip of the sawtooth as compared with the wire electrode, there is a problem that it is vulnerable to contamination by foreign matter such as toner and paper dust, and moreover it is difficult to clean.

The present invention is intended to obtain proper and uniform charging characteristics at a low voltage for the corona discharge device having such a narrow and flat structure.

The present invention also provides a saw-tooth electrode type corona discharge device which is resistant to contamination by foreign matter such as toner and paper dust and is easy to clean.

FIG. 4 is an enlarged sectional view showing an embodiment of a corona charger in which the saw-tooth electrodes 111 are arranged in two rows in parallel, and FIG. 5 is another embodiment of a corona charger in which the saw-tooth electrodes 111 are arranged in two rows in parallel. An enlarged cross-sectional view showing an example, FIG. 6 is a perspective view of an electrode portion of a corona charger in which the sawtooth electrodes are arranged as shown in FIG. 4,
FIG. 7 is a front view of the electrode portion. FIG. 4 shows two insulating substrates 117A and 117B for the sawtooth electrode portion 120A,
An example in which 120B are arranged in the same direction is shown. FIG.
Shows an example in which the saw-tooth electrode portions 120A and 120B are arranged so as to face the two insulating substrates 117A and 117B, respectively. The two sawtooth electrodes 111A and 111B provided on the corona charger 11 shown in these figures are provided on the insulating substrates 117A and 117B, respectively.
0A and 120B are integrally formed by means such as vapor deposition or etching. Alternatively, the sawtooth electrode portions 120A, 120 made of a conductive thin plate such as a stainless steel plate
B is bonded to the insulating substrates 117A and 117B, respectively. The sawtooth electrodes 111A and 111B are 3 to 10 k
It is connected to a power source 110 that applies a high voltage of V.

The pointed portion 120a of the sawtooth electrode 111 facing the control electrode 116 is arranged in parallel with a position slightly retracted from the tip portion 117a of the insulating substrate 117.

The insulating substrate 117 is made of a material such as a ceramic plate or an epoxy resin plate that does not cause dielectric breakdown even when a high voltage is applied.

Further, when discharge between the saw-tooth electrode 111 and the shield plate 112 becomes a problem, an insulating coating member 118 may be provided on the surface opposite to the insulating substrate 117. As a means for providing the insulating covering member 118 on the sawtooth electrode 111, a means such as laminating and adhering an insulating resin film, coating an insulating paint, or performing a resin treatment such as Teflon is applied. To be done. The tip end portion of the insulating coating member 118 facing the control electrode 116 is arranged in parallel with a position slightly retracted from the pointed portion 111a of the sawtooth electrode 111.

By forming the saw-toothed electrode portion 120 on the insulating substrate 117 in this manner, the corona charger can be easily handled during maintenance, inspection and repair. It exhibits excellent effects such as easy cleaning.

By arranging a plurality of sawtooth electrodes 111, the area of the sawtooth electrode tip portion 120a increases, so that it becomes resistant to dirt by toner, paper dust, etc., and stable discharge performance for a long time can be obtained. Even if the size of 11 is reduced, sufficient discharge performance can be obtained, and other excellent effects are exhibited.

FIG. 8 is a front view of a discharge electrode portion in which a plurality of independent sawtooth electrodes 119 are arranged. Multiple independent sawtooth electrodes 1
19 are arranged in parallel on the insulating substrate 117. Each of the plurality of independent sawtooth electrodes 119 has an electric resistance R
It is connected to the power source 110 via. Then, the plurality of independent sawtooth electrodes 11 facing the control electrode 116.
Nine pointed heads 119a are arranged in parallel with each other at a position slightly retracted from the tip end 117a of the insulating substrate 117.

FIG. 9A shows the two insulating substrates 11
7A, 117B and the two sawtooth electrode parts 120A, 1
FIG. 9 is a front view showing an embodiment in which 20B and 20B are arranged in parallel.
(B) is the AA sectional view. Although the drawings show the integrated sawtooth electrode parts 120A and 120B, the present invention is also applicable to the independent sawtooth electrodes 119A and 119B.

If the pitch p between the adjacent peaks 120a, 120a of the sawtooth electrode section 120A 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 required to be 2 mm or more for stabilizing the discharge.

In the corona discharge device shown in FIG. 4 in which a plurality of sawtooth electrodes 111 are arranged in parallel, the sawtooth electrode portion 12 is also provided.
The distance between the pointed portions 120a and 120b before and after 0A and 120B must be 2 mm or more. Therefore, the back-to-back arrangement of the saw-tooth electrode portions 120A and 120B shown in FIG. 5 has an advantage that the corona discharge device can be made more compact than the arrangement of the saw-tooth electrode portions 120A and 120B shown in FIG.

The sawtooth electrode portions 120A and 120B are also provided.
Are arranged in parallel as shown in FIG. 9 (C) and arranged in the same phase, each tip 1 of the sawtooth electrode portions 120A and 120B is
The distance W between 20a and 120b is determined by the insulating substrate 117.
It is equal to the distance D1 between A and 117B.

However, the sawtooth electrode portions 120A, 120
If the phase of B is shifted by a half pitch as shown in FIG. 9B, if the distance W between the pointed portions 120a and 120b of the sawtooth electrode portions 120A and 120B is a constant distance, the sawtooth electrode 111A is obtained. , 111B can be narrowed. For example, the pitch p between adjacent cusps on the same plane is p =
2 mm, the peak portion 120a between the two front and rear, in order to set the distance W = 2 mm between 120b, the distance D2 = 3 ^1/2 mm (1.73mm) next to the insulating substrate, the distance D2 above The distance D1 can be shortened as compared with the interval D1.

FIG. 10A shows three sawtooth electrodes 11
1A, 111B, and 111C are cross-sectional views showing an embodiment in which they are arranged in parallel, and FIG. 10B is a cross-sectional view taken along the line AA of the electrode portion. Also in this embodiment, three sawtooth electrodes 111A,
If the phases of 111B and 111C are shifted from each other by a half pitch as in the case of FIG. 9, the sawtooth electrode portions 120A,
120B, 120C each point 120a, 120b, 1
If the distance W between 20c is a constant distance, the independent sawtooth electrode 1
The respective short distances of 11A, 111B and 111C can be narrowed. Although the drawing shows the integrated sawtooth electrode 111, the present invention is also applicable to the independent sawtooth electrodes 119A and 119B.

FIG. 11 is a sectional view showing various embodiments of a power source for applying a voltage to the sawtooth electrode or the independent sawtooth electrode.

FIGS. 11A, 11B and 11C are sectional views of a corona discharge device comprising two sawtooth electrodes 111A and 111B, and FIGS. 11D, 11E and 11F show three saw teeth. Electrode 11
It is sectional drawing of the corona discharge device which consists of 1A, 111B, and 111C.

FIGS. 11A and 11D show a common power source 110 for applying the same DC voltage to all the sawtooth electrodes. That is, the plurality of sawtooth electrodes 111A,
By applying the same DC voltage to 111B and 111C, the same discharge is performed at a plurality of places. As a result, effects such as stable charging and sufficient charging with a smaller discharge current can be obtained.

11 (B) and 11 (E), the sawtooth electrode 111A located upstream of the image carrier 10 in the moving direction of the plurality of corona discharge electrodes is shown as a first DC power source 110A.
Corona discharge device in which the other sawtooth electrodes 111B and 111C are connected to the second DC power supply 110B and the voltage of the first DC power supply 110A is set higher than the voltage of the second DC power supply 110B. . As a result, the insufficiently charged portion on the upstream side can be made uniform on the downstream side. In this voltage application method, the most upstream sawtooth electrode 111
Except for A, only insufficient charging is compensated for, so that a sufficient DC voltage lower than the voltage applied to the most upstream sawtooth electrode 111A can provide a sufficient charging uniformity effect.

In FIGS. 11C and 11F, among the plurality of corona discharge electrodes, the sawtooth electrode 111A located on the upstream side in the moving direction of the image carrier 10 is connected to the AC power supply 110C, and the other electrodes are connected. This is a corona discharge device in which the sawtooth electrodes 111B and 111C are connected to a DC power supply 110B. As a result, the image carrier 10 is driven by the most upstream AC power supply 110C.
The charge remaining on the surface is removed (charge removal) and charging is performed at the same time. Since this alone is not sufficient for charging, the saw-tooth electrodes 111B and 111C downstream thereof are used for uniform charging by the DC power supply 110B. This voltage application method has an advantage that pre-charge elimination and uniform charging can be performed at the same time.

These power supply connections can also be applied to the independent sawtooth electrodes 119A, 119B and 119C.

FIG. 12A shows the sawtooth electrode 111 or the independent sawtooth electrode 119 which is the corona discharge electrode.
3 is a cross-sectional view of a corona discharge device including a plurality of electrode plates formed on both sides of an insulating substrate 117. FIG. FIG.
2 (B) is a front view of the electrode portion including the sawtooth electrode portions 120A and 120B and the insulating substrate 117D, and FIG. 12 (C) is a sectional view taken along the line AA of the electrode portion. The insulating substrate 117D of this embodiment is the insulating substrates 117A and 11A in FIG.
7B is integrated. The thickness of the insulating substrate 117D is, as shown in FIG.
When B are arranged in parallel as shown in FIG. 9C and arranged in the same phase, the distance W between the pointed portions 120a and 120b of the sawtooth electrode portions 120A and 120B becomes equal to that of the insulating substrate 11.
Almost equal to 7D thickness.

However, the sawtooth electrode portions 120A, 120
If the phase of B is shifted by a half pitch as shown in FIG. 12C, if the distance W between the tip parts 120a and 120b of the sawtooth electrode parts 120A and 120B is set to a constant distance,
The closest distance between the sawtooth electrode portions 120A and 120B can be narrowed. For example, in order to set the pitch p between adjacent cusps on the same plane to be 2 mm and the distance W between the two front and rear cusps 120a and 120b to be W = 2 mm, the insulating substrate 11 should be used.
The thickness of 7D is approximately D = 3 ^1/2 mm (1.73 mm), and this distance D can be shortened as compared with the above distance W.

FIG. 13 is a sectional view showing various embodiments of a power supply for applying a voltage to the sawtooth electrode or the independent sawtooth electrode.

FIG. 13A shows a central insulating substrate 117.
Sawtooth electrode portions 120A and 120B are formed on both surfaces of D, and a common power supply 110 for applying the same DC voltage to the sawtooth electrode portions 120A and 120B is provided. That is, by applying the same DC voltage to the two sawtooth electrode portions 120A and 120B, the same discharge is performed at a plurality of places. As a result, effects such as stable charging and sufficient charging with a smaller discharge current can be obtained.

FIG. 13B shows the two sawtooth electrode portions 1
Of the 20A and 120B, the sawtooth electrode section 120A located upstream in the moving direction of the image carrier 10 is connected to the first DC power supply 110A, and the downstream sawtooth electrode section 120B is connected to the second DC power supply 110B. Then, the first DC power source 11
It is a corona discharge device in which the voltage of 0 A is set higher than the voltage of the second DC power supply 110B. As a result, the insufficiently charged portion on the upstream side can be made uniform on the downstream side. In this voltage application method, the most upstream sawtooth electrode section 120
Except for A, it is only to compensate for insufficient charging, so a DC voltage lower than the voltage applied to the most upstream sawtooth electrode 120A,
A sufficient charge uniformization effect can be obtained.

In FIG. 13C, a saw-toothed electrode portion 120A of the plurality of corona discharge electrodes, which is located on the upstream side in the moving direction of the image carrier 10, is connected to an AC power source 110C.
It is a corona discharge device in which the other sawtooth electrode portion 120B is connected to the DC power supply 110B. As a result, the most upstream AC power supply 110C removes (eliminates) the electric charge remaining on the surface of the image carrier 10 and charges it at the same time. Since this alone is not sufficient for charging, the DC power supply 110B performs uniform charging at the sawtooth electrode portion 120B downstream thereof. This voltage application method has an advantage that pre-charge elimination and uniform charging can be performed at the same time.

These power supply connections can also be applied to the independent sawtooth electrodes 119A and 119B.

In the image forming apparatus of the embodiment shown in FIG. 1, since the exposure optical system is provided inside the photosensitive drum, the adjoining member of the corona discharge device is the cleaning means, pre-charging exposure means or There is a developing means. In the image forming apparatus in which the exposure optical system is provided on the outer side of the photoconductor drum, there are other exposing means such as cleaning means, pre-charging exposure means, and developing means as adjacent members, so that the external shape can be freely set. By using the corona discharge device of the invention, a space is effectively used and a compact image forming apparatus is provided.

The corona discharge device of the present invention 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. 14 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 those in FIG. 1 of the above embodiment are designated by the same reference numerals. Further, points different from the above embodiment will be described.

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 the horizontal direction between the rotary roller and the 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 has its peripheral surface rubbed against the guide member 102 by the biasing force of the tension roller to form an image forming surface.

Reference numerals 11Y, 11M, 11C and 11K are scorotron charging type corona chargers, and are provided on the photosensitive belt 101.
The above-mentioned organic photosensitive layer is charged by a corona discharge by a control electrode (grid) and a sawtooth electrode held at a predetermined potential, and a uniform potential is given to the photosensitive belt 100.

12Y, 12M, 12C, and 12K are FL, EL, PL, LEDs in which light emitting elements are arranged in a line in the depth direction of the photosensitive belt 101, or LISA, PLZT in which elements having an optical shutter function are arranged in parallel. An exposure optical system composed of an LCS 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 be supplied to the respective 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 of the developing devices 13 (Y to K) is charged by the corona charger 11 (Y to K) described above, and the exposure optical system 1 is used.
The electrostatic latent image formed on the photosensitive belt 100 by image exposure with 2 (Y to K) is reversely developed in a non-contact state by applying a developing bias voltage.

In the above-mentioned color image forming apparatus, 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 corona chargers 11Y, 11M, 11C and 11K are also arranged in parallel in a plurality of columns as shown in FIG. As a result, corona charging can be made uniform and stable, and sufficient charging can be performed with a smaller discharge current.

FIG. 15 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 those in FIG. 1 of the above embodiment are designated by the same reference numerals. Further, points different from the above embodiment will be described.

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, charging, image exposure and development are repeated on the peripheral surface of the image carrier 10 to form different color toner images so as to form a color toner image, and the color toner image is transferred to the corona transfer device 14A. The transfer material is transferred to a transfer material by a corona discharge separator 14B, and the transfer material is separated from the image carrier 10 by a corona charge-eliminating separator 14B. To be discharged to. A corona charger 11 and a corona transfer device 1 which are mounted on this image forming apparatus and serve as a corona discharge device.
The present invention is also applicable to 4A and corona charge removal separator 14B.

[0076]

In the corona discharge device of the present invention, the saw-tooth electrodes are arranged in parallel in a plurality of columns and a plurality of power supplies for applying a high voltage are provided to improve the uniformity and stability of charging and reduce discharge. Since sufficient charging can be performed with an electric current, charging efficiency can be improved. Further, since the corona discharge device can be arranged in the narrow space between the image forming processing means, the image forming processing space is effectively used, and it is possible to use the small-diameter photosensitive drum, and the shape is reduced. A compact image forming apparatus is provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image forming apparatus having a corona discharge device of the present invention.

FIG. 2 is a partially enlarged sectional view of the image forming apparatus shown in FIG.

FIG. 3 is a side view of the corona charger shown in FIG.

FIG. 4 is an enlarged sectional view showing an embodiment of a corona charger used in the present invention.

FIG. 5 is an enlarged sectional view showing another embodiment of the corona charger used in the present invention.

FIG. 6 is a perspective view of an electrode portion of a corona charger using a sawtooth electrode.

FIG. 7 is a front view of the electrode section.

FIG. 8 is a front view of a discharge electrode section in which a plurality of independent sawtooth electrodes are arranged.

FIG. 9 is a front view showing an embodiment of an electrode portion in which two insulating substrates and two sawtooth electrodes are arranged in parallel;
-A sectional drawing.

10A and 10B are a sectional view and an AA sectional view showing an embodiment of an electrode portion in which three insulating substrates and three sawtooth electrodes are arranged in parallel.

FIG. 11 is a cross-sectional view showing various embodiments of a power supply for applying a voltage to a sawtooth electrode or an independent sawtooth electrode and a corona discharge device.

FIG. 12 is a cross-sectional view of a corona discharge device in which corona discharge electrodes are formed on both sides of an insulating substrate, a front view of an electrode portion including a sawtooth electrode and an insulating substrate, and AA of the electrode portion.
Sectional view.

FIG. 13 is a cross-sectional view showing various embodiments of a power supply and a corona discharge device for applying a voltage to a sawtooth electrode or an independent sawtooth electrode.

FIG. 14 is a configuration diagram showing another embodiment of the image forming apparatus including the corona discharge device of the present invention.

FIG. 15 is a configuration diagram showing still another embodiment of the image forming apparatus having the corona discharge device of the present invention.

FIG. 16 is a configuration diagram of a corona discharge device having a conventional sawtooth electrode.

[Explanation of symbols]

10 photoconductor drum (image carrier) 100 photoconductor belt (image carrier) 11, 11Y, 11M, 11C, 11K corona charger 110, 110A, 110B, 110C power supply 111, 111A, 111B, 111C sawtooth electrode (corona discharge) Electrodes) 120, 120A, 120B, 120C Sawtooth electrode portions 120a, 120b, 120c, 119a, 119b
Pointed portion 112 Shield plate 113 Electrode plate holding member 114 Holding member 116 Control grid 117, 117A, 117B, 117C Insulating substrate 119 Independent sawtooth electrode (corona discharge electrode) 12Y, 12M, 12C, 12K Exposure optical system 13Y, 13M, 13C, 13K Development device 14A Corona transfer device 14B Corona charge removal separator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Komatsu 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Satoshi Haneda 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company

Claims (22)

[Claims] 1. A corona discharge electrode in which a plurality of discharge electrodes are linearly formed, a control grid which is located between the corona discharge electrode and the image carrier, and which controls a surface potential of the image carrier, In a corona discharge device having plate-shaped shield plates located on both sides of a corona discharge electrode, the corona discharge electrodes are a plurality of electrode plates respectively held by a plurality of insulating substrates arranged in parallel. Corona discharge device characterized by. 2. The corona discharge device according to claim 1, wherein the corona discharge electrode is a sawtooth electrode integrally formed by linearly arranging a plurality of sawtooth-shaped cusps. 3. The corona discharge electrode is a corona discharge electrode formed by linearly arranging a plurality of independent discharge electrodes each having a serrated point. Corona discharge device as described. 4. The corona discharge device according to claim 1, wherein the plurality of corona discharge electrodes arranged in parallel have an interval of 2 mm or more. 5. The front end of the corona discharge electrode facing the image carrier is provided at a position where it does not protrude from the front end of the insulating substrate.
The corona discharge device according to any one of 1. 6. A corona discharge electrode comprising a plurality of serrated pointed portions is a plurality of electrode plates arranged in parallel,
The corona discharge device according to any one of claims 1 to 4, wherein the respective pointed portions of the electrodes that are adjacent and adjacent to each other are arranged so as to be displaced from each other in the longitudinal direction. 7. 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. 8. The plurality of corona discharge electrodes are all
The corona discharge device according to claim 1, wherein the corona discharge device is connected to a common power source for applying a DC voltage. 9. Among the plurality of corona discharge electrodes, an electrode located upstream in the moving direction of the image carrier is connected to a first DC power supply, and the other electrodes are connected to a second DC power supply. The corona discharge device according to claim 1, wherein the first DC power supply voltage is set higher than the second DC power supply voltage. 10. Of the plurality of corona discharge electrodes,
The corona discharge device according to claim 1, wherein an electrode located on the upstream side in the moving direction of the image carrier is connected to an AC power source, and the other electrodes are connected to a DC power source. 11. A corona discharge electrode in which a plurality of discharge electrodes are linearly formed on an insulating substrate, and is 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 control grid and plate-shaped shield plates located on both sides of the corona discharge electrode, the corona discharge electrodes are a plurality of electrode plates formed on both sides of an insulating substrate. Corona discharge device characterized by. 12. The corona discharge device according to claim 11, wherein the corona discharge electrode is a sawtooth electrode integrally formed by linearly arranging a plurality of sawtooth-shaped cusps. 13. 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 as described. 14. The corona discharge device according to claim 11, wherein the plurality of corona discharge electrodes arranged in parallel have an interval of 2 mm or more. 15. The front end of the corona discharge electrode facing the image carrier is provided at a position not protruding from the front end of the insulating substrate. The corona discharge device according to the item. 16. The corona discharge electrode composed of a plurality of serrated points is a plurality of electrodes arranged in parallel,
15. The corona discharge device according to claim 11, wherein the pointed portions of the electrodes that are adjacent and adjacent to each other are arranged so as to be offset from each other in the longitudinal direction. 17. The plurality of independent discharge electrodes comprises:
14. The corona discharge device according to claim 13, wherein the corona discharge device is connected to a common power source to which a high voltage is individually applied via electric resistance. 18. The corona discharge device according to claim 11, wherein all of the plurality of corona discharge electrodes are connected to a common power source for applying a DC voltage. 19. Among the plurality of corona discharge electrodes,
The electrode located on the upstream side in the moving direction of the image carrier is connected to a first DC power supply, the other electrodes are connected to a second DC power supply, and the first DC power supply voltage is set to the second DC power supply. The corona discharge device according to claim 11, wherein the corona discharge device is set higher than the voltage. 20. Among the plurality of corona discharge electrodes,
The corona discharge device according to claim 11, wherein an electrode located on the upstream side in the moving direction of the image carrier is connected to an AC power source, and the other electrodes are connected to a DC power source. 21. The corona discharge device includes four sets of image forming means including a corona discharge device, an image exposure means, and a developing device, a transfer means, and a cleaning device in a circumferential direction of a rotating image carrier. When the image carrier is rotated once, the peripheral surface of the image carrier is repeatedly charged, image-exposed and developed to form toner images of different colors, thereby forming a color toner image. The corona discharge device according to claim 1 or 11, wherein the corona discharge device is mounted on a color image forming apparatus that transfers to a transfer material by a transfer unit. 22. The corona discharge device is provided with an image forming device including a corona discharge device, an image exposure device, and a plurality of developing devices, a transfer device, and a cleaning device in a circumferential direction of a rotating image carrier. Then, while rotating the image carrier a plurality of times,
A color image forming apparatus for forming a color toner image by superposing different color toner images by repeating charging, image exposure and development on the peripheral surface of an image carrier and transferring the color toner image to a transfer material by a transfer means. The corona discharge device according to claim 1 or 11, which is mounted.