JP3395026B2 - Corona charging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona discharge type charging device used for charging a photosensitive member in an electrophotographic image forming apparatus. In particular, the present invention relates to a corona discharge type charging device using a non-contact sawtooth electrode. 2. Description of the Related Art Conventionally, as a corona discharge type charging device of this type, a wire discharge type (corotron, scorotron,
Dicorotron) and pin discharge method (pin electrode type, sawtooth electrode type, etc.). The latter has recently come to be used in electrophotographic copying machines, printers and the like due to low ozone generation. In particular, a corona charger having a structure using an electrode plate provided with a plurality of sawtooth-shaped electrode portions on a single thin plate-shaped member is disclosed in JP-A-63-15272 and JP-A-5-45999. Have been. However, in a corona discharge from a corona charging device using a saw-tooth electrode plate having a plurality of saw-tooth electrode portions provided on a single thin plate-like member, each of the above-mentioned problems can be solved. The state of discharge from the sawtooth portion is non-uniform, requiring a large amount of discharge current for uniform charging. FIG. 10 is a diagram showing a discharge state of a corona charger using a saw-tooth electrode plate, and FIG. 11 is a diagram showing a discharge intensity distribution from one saw-tooth electrode. Position (L) from the vertex on the horizontal axis centering on the vertex (O),
The vertical axis indicates the strength (E), and the sawtooth electrode plate 61 is a discharge electrode of a corona charger made using the sawtooth electrode plate.
1, and when a voltage is applied to the control grid 615, a corona discharge occurs with directivity of the discharge between the electrode and the photosensitive drum, and ions due to the discharge from the apex 611b of the sawtooth electrode 611a are almost completely discharged from the control grid 615. Head in the direction. Therefore, discharge is performed without being affected by the opening angle and without lowering the charging performance. However, the corona discharge from the saw-tooth electrode has a higher discharge capacity than the wire discharge method, but the non-uniformity of the discharge from the individual saw-tooth electrode is promoted. A phenomenon was observed. Further, in a corona charging device using a saw-tooth electrode plate having a plurality of saw-tooth electrodes provided on a single thin plate-like portion, the tip of the saw-tooth electrode is easily broken, so that the corona charging device can be easily assembled. There is a problem in that the sawtooth electrode of the sawtooth electrode plate is damaged or damaged at the time of cleaning at the time of maintenance, and the cleaning is difficult. SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and does not damage parts during assembling of the saw-tooth electrode or cleaning of dirt on the saw-tooth electrode, and stabilizes the discharge performance of corona discharge. It is an object of the present invention to provide a corona charging device. SUMMARY OF THE INVENTION The object of the present invention is to provide a corona discharge saw-tooth electrode plate in which saw-tooth electrodes facing an image forming body for forming a latent image are arranged at a constant pitch. in the corona charging device provided with a support member for supporting the first
A first sawtooth electrode plate and a second sawtooth electrode plate,
In the tooth electrode plate, the support member supports the first sawtooth electrode plate.
Holding the image forming body in the moving direction of the image forming body.
The apex side of the root of the first sawtooth electrode is arranged on the upstream side,
The second saw-tooth electrode plate may be configured such that the support member includes the second sawtooth electrode.
When the tooth electrode plate is supported, it faces the moving direction of the image forming body.
And the vertex side of the second sawtooth electrode is on the downstream side.
And a slope formed on the support member such that a vertex side of a root of the first and second saw-tooth electrodes is closer to the image forming body, and provided on the slope of the support member. The entire surface of the first and second sawtooth electrodes is joined to the corona charging device. [Embodiment 1] FIG. 1 and FIG. 2 show the configuration of a scorotron charger which is an embodiment of a corona charger according to the present invention.
This will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a scorotron charger showing one embodiment of a corona charger of the present invention, and FIG. 2 is a sectional view of the scorotron charger of FIG. The sawtooth electrode plate 110 is an electrode plate for corona discharge, and has a strip-shaped plate portion 111, a voltage application terminal 114 provided at an end portion, and a plurality of strip electrodes provided at the strip-shaped end of the plate portion 111. The vertex 113 of the saw-tooth electrode 112, which is an equal-length electrode portion, is formed with the saw-tooth electrode 112 provided at a constant pitch, and is arranged to face the photosensitive drum 10 as an image forming body. The sawtooth electrode plate 110 is
For example, it is formed by etching a stainless steel plate which is a thin conductive plate having a thickness of 100 μm, and the curvature of the apex 113 of the sawtooth electrode 112 is R = 40 μm or less. The control grid 105 is formed, for example, by etching a stainless steel plate having a thickness of 0.1 mm, and has mounting holes 105a and 105b at its ends. The shield 103, which is a shield member, is made of, for example, stainless steel, has an opening having a U-shaped cross section, and has holes 103a, 103b at its ends.
Is provided. The support member 120 is made of an insulating resin such as AB
It is made of S resin and includes a support portion 123 having a trapezoidal cross section at the center and end portions 121 and 122 at both ends. Support Department 1
23 has a tapered portion 123 for attaching the sawtooth electrode plate 110.
a is provided. The end portion 121 is provided with a groove 124 for inserting the voltage application terminal 114 of the sawtooth electrode plate 110, and a pin 121a for attaching a shield on the upper surface,
Pin 121 for attaching control grid 105 to bottom 125
b. The end 122 has a shield mounting pin 122a on the top surface and the control grid 105 on the bottom 126.
And a pin 122b for attaching the same. A voltage application terminal 1 provided on the sawtooth electrode plate 110
14 is inserted into the tapered portion 123a provided on the sawtooth electrode plate 110 while inserting the sawtooth electrode plate 110 into the groove 124 provided on the end 121 of the support member 120.
It is pasted to the support member 120 including the twelve apexes 113, and joined and fixed. Preferably, the voltage application terminal 114 is flush with or slightly protrudes from the groove 124 of the support member 120 in order to couple with a conductive line (not shown). The sawtooth electrode plate 110 may be directly formed by etching a material obtained by bonding a conductive thin plate to the support member 120 in advance. In this state, the plate
Since the entire surface of the sawtooth electrode plate 110 provided with 111 and the sawtooth electrode 112 is joined to the support member 120, the sawtooth electrode 112 is not damaged by other members. The support member 1 on which the sawtooth electrode plate 110 is mounted
Pins 121a and 122a provided on the upper surface of
3 holes 103a, 103b are fitted, and pins 121a, 122a are
For example, the shield 103 is fixed to the support member 120 by heat caulking by ultrasonic fusion. Furthermore, the end 121 of the support member 120
And a pin 122 provided at the end 122.
b, holes 105a provided at both ends of the control grid 105,
105b is fitted, and the pins 121b and 122b are thermally caulked by, for example, ultrasonic fusion, and the control grid 105 is attached to the support member 120.
And the corona charging device 100 is completed. In this state, the sawtooth electrode 112 is further protected. Also, the head of the thermal caulking by ultrasonic fusion of the pins 121b and 122b protrudes from the plate surface of the control grid 105, so that even if the head is placed on a member (not shown),
105 is protected from being damaged. The U-shaped both ends of the shield 103 and the control grid 105 come into contact with each other to be in a conductive state. In the above assembly, the sawtooth electrode plate 110 may be attached after the shield 103 is attached to the support member 120, and the control grid 105 is fixed to the support member 120 to which the sawtooth electrode plate 110 is attached. After that, an assembling method of attaching and fixing the shield 103 to the support member 120 can be adopted. Next, the arrangement of the sawtooth electrode plate joined to the support member for the photosensitive drum and the discharge distribution of corona charging from the sawtooth electrode will be described with reference to FIGS. FIG. 3 is a view showing the arrangement of the sawtooth electrode plate joined to the support member with respect to the photosensitive drum, and FIG. 4 is a view showing the intensity distribution of discharge from the sawtooth electrode of FIG. The position (L) from the vertex on the horizontal axis centering on (O),
The vertical axis indicates the intensity (E). FIG. 3A shows a saw-tooth electrode plate 110 bonded to a support member 220 with the apex 113 of the saw-tooth electrode 112 facing the photoconductor drum 10 and orthogonal to the photoconductor drum 10. FIG. 4A shows a discharge distribution of corona charging from the apex 113 of the sawtooth electrode 112, as shown in FIG.
The discharge concentrates on the central portion (O) of the sawtooth electrode, the discharge distribution does not spread uniformly, and the potential control ability by the control grid 105 is slightly inferior. In addition, the supporting member 220 at a location where the discharge is concentrated is easily deteriorated by ozone. FIG. 3B shows that the sawtooth electrode plate 110 bonded to the support member 220 has the apex 113 of the sawtooth electrode 112 facing the photosensitive drum 10 and the apex 113 of the sawtooth electrode 112 faces the photosensitive drum.
Apex 113 of the sawtooth electrode 112
And the point 10a at the shortest distance from the vertex 113 to the photosensitive drum 10.
FIG. 4B shows a case where the corona discharge from the apex 113 of the sawtooth electrode 112 is distributed at a central portion of the sawtooth electrode, as shown in FIG. As shown in (O), the discharge distribution that is almost uniform and has a high discharge capability spreads, and the potential control capability by the control grid 105 becomes extremely good. Further, ozone deterioration of the support member 220 due to discharge is small. FIG. 3C shows a case where the sawtooth electrode plate 110 joined to the supporting member 220 is arranged horizontally with respect to the photosensitive drum 10, and the sawtooth electrode 112 extends from the vertex 113 of the sawtooth electrode 112. As shown in FIG. 4 (C), the discharge distribution of the corona charging is slightly lower than the central portion (O) of the apex of the sawtooth electrode, but the discharge distribution spreads very uniformly, and the potential control capability by the control grid 105 is obtained. Is also excellent. Further, there is no ozone deterioration of the support member 220 due to the discharge. As described above, the arrangement with respect to the photosensitive drum is most preferably in the state shown in FIG. 3B, but FIG. 5 shows how the sawtooth electrode is inclined with respect to the moving direction of the photosensitive drum. As shown in FIG. 5A, the sawtooth electrode plate 110 joined to the support member 220 turns the apex 113 of the sawtooth electrode 112 toward the photoconductor drum 10 and moves the photoconductor drum 10 in the moving direction. The vertex 113 side of the saw-tooth electrode 112 is closer to the photoconductor drum 10, the root side is separated, and the photovoltaic drum 10 is arranged so that the vertex 113 is inclined with respect to the photoconductor drum 10. 5B, the vertex 113 side of the sawtooth electrode 112 is located downstream with respect to the moving direction of the photosensitive drum 10, as shown in FIG. In some cases. In both cases, as described with reference to FIG. 4B, the discharge distribution of corona charging from the apex 113 of the saw-tooth electrode 112 is broader than that of the center of the saw-tooth electrode. The configuration shown in FIG. 5A, which has a good potential control ability by the control grid 105 and has a discharge distribution with a wide skirt on the downstream side in the moving direction of the photosensitive drum 10, is most preferable because uniform discharge is achieved. In the case of the configuration (B), the discharge distribution spreads upstream in the moving direction of the photosensitive drum 10 and the discharge is strongest at the exit portion.
Compared to the case of the configuration (A), the charging becomes slightly non-uniform, and the support member is more likely to be degraded by ozone. Embodiment 2 The configuration and discharge distribution of a scorotron charger as another embodiment of the corona charger of the present invention will be described with reference to FIGS. FIG. 6 is a cross-sectional view of a scorotron charger showing another embodiment of the corona charging device of the present invention. FIG. 7 is a diagram showing the intensity distribution of discharge from the sawtooth electrode of FIG. With the intersection (O) extending in the direction from the base to the apex of the electrode as the center, the horizontal axis indicates the position (L) from the intersection and the vertical axis indicates the intensity (E). The general configuration of the scorotron charger 300 is the same as that of the first embodiment, except that tapered portions 323a and 323b are provided on both sides of the support portion 323 of the support member 320, and the tapered portions 323a and 323b are provided.
Each of the sawtooth electrode plates 110a and 110b is bonded to each of the sawtooth electrodes 112a and 112b by, for example, bonding.
a and 113b as a whole are joined and fixed. The shield 103 and the control grid 105 are connected to the sawtooth electrode plates 110a, 110
end 321 (not shown), 322 of support member 320 to which b is joined
The scorotron charger 300 is fixed by, for example, thermal caulking with a pin used in the first embodiment or a resin screw. The moving direction of the photosensitive drum 10 is shown in FIG.
As shown in FIG. 7, the discharge distribution of the scorotron charger 300 arranged as shown in FIG. 7 is centered on the intersection (O) on the extension from the root of the two sawtooth electrodes 112a and 112b to the vertices 113a and 113b. The present invention provides a scorotron charger in which a uniform discharge is obtained with a wide and uniform discharge capability, a very high potential control capability by the control grid 105, and uniform charging. Next, a configuration in which a scorotron charger as a corona charging device is provided with a cleaning means will be described with reference to FIGS. FIG. 8 is a sectional view of the scorotron charger of FIG. 6 provided with a cleaning unit, and FIG.
It is a side view of the scorotron charger of FIG. A cleaning means 500 is provided at one end inside the scorotron charger 300. On the upper part of the U-shaped shield 103, two cleaning means 500 slide in the longitudinal direction. Long grooves 103c and 103d are provided, and long grooves 323c and 323d for sliding the cleaning means 500 are also provided at both ends of the support portion 323 of the support member 320 in parallel with the shield 103, and a plate 501 having spring properties is provided.
a and 501b are fitted through the long grooves 103c and 323c and the long grooves 103d and 323d provided in the shield 103 and the support member 320, respectively.
502a and 502b are adhered to the plates 501a and 501b, and the knob 503 is attached while the sawtooth electrode plates 110a and 110b including the vertices 113a and 113b are sandwiched between the cleaning pads 502a and 502b. Attached to. At the time of maintenance and inspection of the scorotron charger, the knob 503 provided on the cleaning means 500 is held, and the sliding long grooves 103c and 323c of the cleaning means 500 provided on the shield 103 and the support member 320 are provided. Long groove 103d,
323d and the cleaning means 5 in the direction of the arrow in FIG.
Then, the cleaning pads 502a and 502b are slid over the sawtooth electrodes 110a and 110b to move the sawtooth electrodes 110a and 110b.
Clean b. Since the sawtooth electrodes 110a and 110b are joined to the support portion 323 of the support member 320, they are not damaged or damaged during cleaning. The cleaning means described in the second embodiment can of course be applied to the scorotron charger described in the first embodiment. Further, in the above-described embodiment, the cylindrical photoconductor drum has been described as the image forming body. However, the image forming body is not necessarily limited to the cylindrical shape, and may include a belt photoconductor having a horizontal image forming surface. According to the first aspect, the saw-tooth electrode is not damaged or damaged at the time of assembling the scorotron charger, which is a corona charging device, or at the time of maintenance and inspection. According to the second aspect of the present invention, there is provided a scorotron charger having a uniform discharge distribution having a high discharge ability and having a good potential control ability by a control grid. According to the third aspect of the present invention, there is provided a scorotron charger having a discharge distribution which is more uniform, has a higher discharge capability, has a very good potential control capability by a control grid, and causes less ozone deterioration of a support member due to discharge. Is done. According to the fourth aspect of the present invention, there is provided a scorotron charger having a cleaning means that does not damage or damage the sawtooth electrode during maintenance and inspection.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a scorotron charger showing one embodiment of a corona charger of the present invention. FIG. 2 is a sectional view of the scorotron charger of FIG. FIG. 3 is a diagram illustrating an arrangement of a sawtooth electrode plate joined to a support member with respect to a photosensitive drum. FIG. 4 is a diagram showing an intensity distribution of electric discharge from the sawtooth electrode of FIG. 3; FIG. 5 is a diagram showing how a sawtooth electrode is inclined with respect to a moving direction of a photosensitive drum. FIG. 6 is a sectional view of a scorotron charger showing another embodiment of the corona charger of the present invention. FIG. 7 is a view showing an intensity distribution of discharge from the sawtooth electrode of FIG. 6; 8 is a cross-sectional configuration diagram in which cleaning means is provided in the scorotron charger of FIG. FIG. 9 is a side view of the scorotron charger of FIG. 8; FIG. 10 is a diagram showing a discharge state of a corona charger using a sawtooth electrode plate. FIG. 11 is a diagram showing an intensity distribution of discharge from one sawtooth electrode. [Description of Signs] 10 Photoconductor drum 100, 300 Scorotron charger 103 Shield 105 Control grid 110, 110a, 110b Sawtooth electrode plate 113, 113a, 113b Apex 120, 220, 320 Support members 123, 323 Support portions 123a, 323a, 323b Taper portion 500 Cleaning means 502a, 502b Cleaning pad 503

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-2314 (JP, A) JP-A-7-5746 (JP, A) JP-A-7-43990 (JP, A) JP-A-2- 256077 (JP, A) JP-A-5-224507 (JP, A) JP-A 56-23955 (JP, U) JP-A 61-101757 (JP, U) (58) Fields investigated (Int. Cl. ^7, DB name) G03G 15/02 G03G 15/16 102 H01T 19/00

Claims (1)

(57) [Claim 1] A sawtooth electrode plate for corona discharge in which sawtooth electrodes facing an image forming body for forming a latent image are arranged at a constant pitch, and the sawtooth electrode plate is supported. In a corona charging device provided with a support member, a first saw-tooth electrode plate and a second saw-tooth electrode
An electrode plate, wherein the first saw-tooth electrode plate has
When the first sawtooth electrode plate is supported, the
In the moving direction, the top of the first sawtooth electrode is higher than the root of the first sawtooth electrode.
The point side is located upstream and the second sawtooth electrode plate is
When the supporting member supports the second sawtooth electrode plate,
With respect to the moving direction of the image forming body, the second sawtooth electrode
The vertex side is located downstream from the root, and the first
And an inclined surface formed such that a vertex side of the second saw-tooth electrode is closer to the image forming body than the root of the second sawtooth electrode is provided on the support member, and the first and the second surfaces are formed on the inclined surface of the support member.
A corona charger, wherein the entire surface of the second sawtooth electrode is joined.