JPH10319677A - Corona discharge device and image forming apparatus using the same - Google Patents

Abstract

(57) Abstract: In a corona discharge device, the photoconductor is charged sufficiently and uniformly while increasing the peripheral speed of the photoconductor. SOLUTION: A metal shield case 27c having an opening for discharge opened toward a photoreceptor 1, and a partition for partitioning the inside of the shield case 27c into two discharge chambers along the rotation direction of the photoreceptor 1. Plate 27f and first and second corona wires 27a, 27a, which are stretched in the width direction of the photoconductor 1 in the discharge chambers on the upstream and downstream sides in the rotation direction of the photoconductor 1.
27b, a first grid plate 27d attached to the opening of the discharge chamber around which the first corona wire 27a is stretched at a predetermined interval from the first corona wire 27a, and a second corona wire The first corona wire 27a and the first grid plate 27
A corona discharge device is constituted by the second grid plate 27e attached at an interval equal to or longer than the interval d.

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 used in an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus, and an image forming apparatus using the same.

[0002]

2. Description of the Related Art In electrophotographic apparatuses, equipment using dry toner occupies the mainstream, and many copiers, laser printers,
It has been put to practical use as plain paper facsimile, etc., and has achieved remarkable development. The electrophotographic apparatus is an apparatus to which an electrophotographic process technology is applied, and visualizes an electrostatic latent image formed on a photoreceptor with toner particles.

FIG. 3 shows the structure of a corona discharge device in a conventional electrophotographic apparatus. A corona discharge device 2 is provided near a photoreceptor 1 formed by coating a photosensitive drum on the outer peripheral surface of a metal drum as a base material. The corona discharge device 2 includes a metal shield case 2b having an opening formed toward the photoconductor 1, a corona wire 2a stretched in the width direction of the photoconductor 1 in the shield case 2b, and an opening. And a grid plate 2c attached to the portion. Then, the photoconductor 1 is uniformly charged by corona discharge by the corona wire 2a.

When the photosensitive member 1 is irradiated with an exposure light beam 4 obtained from an exposure optical system 3 by modulating light intensity or pulse width of an image signal by a laser driving circuit (not shown), the photosensitive member 1 is exposed. Upon exposure, a predetermined electrostatic latent image is formed.

Here, in an image forming apparatus including an electrophotographic apparatus, recently, a high printing speed has been demanded in order to improve work efficiency and cope with large-volume printing.

In order to increase the printing speed, it is necessary to increase the peripheral speed of the photosensitive member 1.

[0007]

However, if the peripheral speed of the photosensitive member 1 is increased in the electrophotographic apparatus having the above structure, it is not possible to secure a sufficient time for the photosensitive member 1 to pass through the opening of the corona discharge device 2. . As a result, problems such as a reduction in charging efficiency and occurrence of discharge unevenness occur, and image quality deteriorates.

Accordingly, an object of the present invention is to provide a corona discharge device capable of sufficiently and uniformly charging a photosensitive member while increasing the peripheral speed of the photosensitive member, and an image forming apparatus using the same. .

[0009]

In order to solve this problem, a corona discharge device according to the present invention is a metal-made corona discharge device having a discharge opening opened toward a photosensitive member on which an electrostatic latent image is formed. A shield case, a partition plate for partitioning the inside of the shield case into two discharge chambers along the rotation direction of the photoconductor, and a discharge chamber upstream of the rotation direction of the photoconductor in a width direction of the photoconductor. A first corona wire, a second corona wire stretched in the width direction of the photoconductor in the discharge chamber on the downstream side in the rotation direction of the photoconductor, and an opening of the discharge chamber stretched by the first corona wire. A first grid plate attached to the portion at a predetermined distance from the first corona wire;
And a second grid plate attached to the opening of the discharge chamber on which the corona wire is stretched, with an interval larger than the interval between the first corona wire and the first grid plate.

A corona discharge device according to the present invention includes a metal shield case having a discharge opening opened toward a photoreceptor on which an electrostatic latent image is formed, and a photoreceptor inside the shield case. In a partition plate partitioned into two discharge chambers along the rotation direction, and in a discharge chamber on the upstream side in the rotation direction of the photoconductor,
A first corona wire stretched in the width direction of the photoconductor, a second corona wire stretched in the width direction of the photoconductor in a discharge chamber on the downstream side in the rotation direction of the photoconductor, and a first corona wire. The first is attached to the opening of the discharge chamber where the wire is stretched.
And a second grid plate attached to the opening of the discharge chamber in which the second corona wire is stretched, wherein the distance between the first corona wire and the first grid plate is L1. The distance between the first corona wire and the side wall of the shield case is L2, and the distance between the first corona wire and the partition plate is L.
3. The distance between the second corona wire and the second grid plate is L4, the distance between the second corona wire and the partition plate is L5, and the distance between the second corona wire and the side wall of the shield case is L.
6, L2 = L3, L5 = L6 and L1
<L2, L4 <L5.

A corona discharge device according to the present invention comprises a metal shield case having a discharge opening opened toward a photosensitive member on which an electrostatic latent image is formed, and a rotating direction of the photosensitive member in the shield case. A first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoconductor, a first grid plate attached to an opening of the discharge chamber over which the first corona wire is stretched, A second grid plate attached to the opening of the discharge chamber in which the corona wire is stretched.
The distance between the side wall of the shield case and the partition plate in the discharge chamber where the corona wire is stretched is L7, and the distance between the side wall of the shield case and the partition plate in the discharge chamber where the second corona wire is stretched is L8. L8 <L7 <2 ×
Each is arranged so as to satisfy the relationship of L8.

A corona discharge device according to the present invention comprises a metal shield case having a discharge opening opened toward a photoreceptor on which an electrostatic latent image is formed, and a rotating direction of the photoreceptor in the shield case. A first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoconductor, a first grid plate attached to an opening of the discharge chamber over which the first corona wire is stretched, A second grid plate attached to the opening of the discharge chamber in which the corona wire is stretched.
Φ1> φ2 and 40 μm <φ2 <8, where φ1 is the diameter of the corona wire and φ2 is the diameter of the second corona wire.
The diameters of the first and second corona wires are set so as to satisfy the relationship of 0 μm.

A corona discharge device according to the present invention includes a metal shield case having a discharge opening opened toward a photoconductor on which an electrostatic latent image is formed, and a rotating direction of the photoconductor in the shield case. A first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoconductor, a first grid plate attached to an opening of the discharge chamber over which the first corona wire is stretched, A second grid plate attached to the opening of the discharge chamber in which the corona wire is stretched.
When the aperture ratio of the grid plate is R1 and the aperture ratio of the second grid plate is R2, the first and second grid plates satisfy the relationship of 0.4 <R2 / R1 <0.8. The aperture ratio is set.

According to the present invention, there is provided a corona discharge device comprising: a metal shield case having a discharge opening opened toward a photosensitive member on which an electrostatic latent image is to be formed; A first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoconductor and electrically connected to the first corona wire in series, and an opening of the discharge chamber in which the first corona wire is stretched. A first grid plate attached to the portion, and a second grid plate attached to the opening of the discharge chamber around which the second corona wire is stretched.

The image forming apparatus of the present invention uses one of these corona discharge devices.

With such a corona discharge device, the photosensitive member can be charged sufficiently and uniformly while increasing the peripheral speed of the photosensitive member. Further, with such an image forming apparatus, high image quality can be obtained even when high printing speed is achieved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a metal shield case having a discharge opening opening toward a photoreceptor on which an electrostatic latent image is formed, and a shield case. A partition plate for dividing the inside of the case into two discharge chambers along the rotation direction of the photoconductor, and a first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoconductor in the discharge chamber on the downstream side in the rotation direction of the photoconductor;
A first grid plate attached to the opening of the discharge chamber on which the corona wire is stretched at a predetermined interval from the first corona wire, and a discharge chamber on which the second corona wire is stretched A corona discharge device having a second grid plate attached to the opening at a distance equal to or greater than the distance between the first corona wire and the first grid plate.

The invention according to claim 2 of the present invention provides:
A metal shield case having a discharge opening opened toward the photoconductor on which an electrostatic latent image is formed, and a partition for partitioning the inside of the shield case into two discharge chambers along the rotation direction of the photoconductor. A plate, a first corona wire stretched in the width direction of the photoconductor in a discharge chamber on the upstream side in the rotation direction of the photoconductor, and a discharge chamber on the downstream side in the rotation direction of the photoconductor in the width direction of the photoconductor. A second corona wire stretched, a first grid plate attached to an opening of the discharge chamber over which the first corona wire is stretched, and a discharge chamber over which the second corona wire is stretched. A second grid plate attached to the opening, a distance between the first corona wire and the first grid plate being L1, a distance between the first corona wire and a side wall of the shield case being L2, The distance between the first corona wire and the partition plate is L3, and the second Nawaiya and the distance between the second grid plate L4, the distance between the second corona wires and the partition plate L
5, when the distance between the second corona wire and the side wall of the shield case is L6, the coronas are arranged such that L2 = L3, L5 = L6, and satisfy the relationship of L1 <L2, L4 <L5. It is a discharge device.

According to a third aspect of the present invention, there is provided a metal shield case having a discharge opening which is opened toward a photosensitive member on which an electrostatic latent image is formed, and a light-sensitive element provided inside the shield case. A partition plate that divides into two discharge chambers along the rotation direction of the body, and a discharge chamber on the upstream side in the rotation direction of the photoconductor,
A first corona wire stretched in the width direction of the photoconductor, a second corona wire stretched in the width direction of the photoconductor in a discharge chamber on the downstream side in the rotation direction of the photoconductor, and a first corona wire. The first is attached to the opening of the discharge chamber where the wire is stretched.
And a second grid plate attached to the opening of the discharge chamber in which the second corona wire is stretched, and the shield case in the discharge chamber in which the first corona wire is stretched. When the distance between the side wall and the partition plate is L7 and the distance between the side wall of the shield case and the partition plate in the discharge chamber in which the second corona wire is stretched is L8, L8 <L.
The corona discharge devices are arranged so as to satisfy the relationship of 7 <2 × L8.

According to a fourth aspect of the present invention, there is provided a metal shield case having a discharge opening opened toward a photoreceptor on which an electrostatic latent image is formed, and a light-sensitive element in the shield case. A partition plate that divides into two discharge chambers along the rotation direction of the body, and a discharge chamber on the upstream side in the rotation direction of the photoconductor,
A first corona wire stretched in the width direction of the photoconductor, a second corona wire stretched in the width direction of the photoconductor in a discharge chamber on the downstream side in the rotation direction of the photoconductor, and a first corona wire. The first is attached to the opening of the discharge chamber where the wire is stretched.
And a second grid plate attached to the opening of the discharge chamber on which the second corona wire is stretched. The diameter of the first corona wire is φ1, and the diameter of the second corona wire is φ1. When the diameter is φ2, φ1> φ2 and 40 μm <
This is a corona discharge device in which the diameters of the first and second corona wires are set so as to satisfy the relationship of φ2 <80 μm.

According to a fifth aspect of the present invention, there is provided a metal shield case having a discharge opening opened toward a photoreceptor on which an electrostatic latent image is to be formed, and a light-sensitive element in the shield case. A partition plate that divides into two discharge chambers along the rotation direction of the body, and a discharge chamber on the upstream side in the rotation direction of the photoconductor,
A first corona wire stretched in the width direction of the photoconductor, a second corona wire stretched in the width direction of the photoconductor in a discharge chamber on the downstream side in the rotation direction of the photoconductor, and a first corona wire. The first is attached to the opening of the discharge chamber where the wire is stretched.
And a second grid plate attached to the opening of the discharge chamber in which the second corona wire is stretched, wherein the opening ratio of the first grid plate is R1, the second grid plate is 0.4 <R2 / R1 <, where R2 is the aperture ratio of
This is a corona discharge device in which the aperture ratios of the first and second grid plates are set so as to satisfy a relationship of 0.8.

According to a sixth aspect of the present invention, there is provided a metal shield case having a discharge opening opened toward a photoreceptor on which an electrostatic latent image is formed, and a photosensitive element in the shield case. A partition plate that divides into two discharge chambers along the rotation direction of the body, and a discharge chamber on the upstream side in the rotation direction of the photoconductor,
A first corona wire stretched in the width direction of the photoconductor, and in a discharge chamber downstream of the rotation direction of the photoconductor, stretched in the width direction of the photoconductor and electrically connected in series with the first corona wire. A second corona wire connected to the first corona wire and a first corona wire attached to an opening of the discharge chamber on which the first corona wire is stretched.
And a second grid plate attached to the opening of the discharge chamber on which the second corona wire is stretched.

The invention according to claim 7 of the present invention is an image forming apparatus using any one of these corona discharge devices.

According to the invention, the photosensitive member can be charged sufficiently and uniformly while the peripheral speed of the photosensitive member is increased, and high image quality can be obtained even when the printing speed is increased. Has an action.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

(Embodiment 1) FIG. 1 is a schematic diagram of an image forming apparatus using a corona discharge device according to an embodiment of the present invention, and FIG. 2 is a diagram showing the structure of the corona discharge device in the image forming device of FIG. FIG.

The image forming apparatus according to the first embodiment is an electrophotographic apparatus that visualizes an electrostatic latent image formed on a photoreceptor by an electrophotographic process technique using toner particles. As shown in FIG. Using a metal drum such as aluminum as the base material,
The photoreceptor 1 is formed by coating a photosensitive receiving layer such as selenium (Se) or an organic photoconductor (hereinafter, referred to as “OPC”) on the outer peripheral surface thereof in a thin film shape. The photoconductor 1 rotates in the circumferential direction to convey a sheet described later.

A corona discharge device 2 is provided near the photosensitive member 1 as an electrostatic latent image carrier. As shown in detail in FIG. 2, the corona discharge device 2 has a shield case 27c having an opening that opens toward the photoreceptor 1.
have. The inside of the shield case 27c made of a metal conductive member is divided into two discharge chambers along the rotation direction of the photoconductor 1 by a partition plate 27f made of the same material as the shield case 27c. A first corona wire 27a is located on the upstream side in the rotation direction, and a second corona wire 27b is located on the downstream side in the width direction of the photoconductor 1, respectively. In the first embodiment, the first and second corona wires 27a, 27b
Is made of tungsten, and both have a diameter of 60 μm. However, other diameters may be used.

A first grid plate 27d is provided at the opening of the discharge chamber where the first corona wire 27a is stretched, and a second grid plate 27d is provided at the opening of the discharge chamber where the second corona wire 27b is stretched.
Grid plates 27e are respectively attached.

As shown in FIG. 1, a corona current supply power source 28 is connected to the first and second corona wires 27a and 27b, and the first and second grid plates 27d and 27e are provided.
Is connected to a grid bias voltage supply power supply 29. The corona current supply power supply 28 outputs a current of about -1 mA, and the grid bias voltage supply power supply 29
A voltage of 650 V is output. As a result, the first and second corona wires 27a, 27b cause corona discharge, and the first and second grid plates 27d, 27d,
The photosensitive member 1 is uniformly charged via each of the photoconductors 27e.

Further, in the vicinity of the photoreceptor 1, an exposure engineering system for irradiating the photoreceptor 1 with an exposure light beam 4 obtained by subjecting an image signal to light intensity modulation or pulse width modulation by a laser driving circuit (not shown). 3 are installed. Then, the photoconductor 1 is exposed by the exposure light beam 4 to form a predetermined electrostatic latent image.

The toner 10 agitated and conveyed by a toner agitating member 11 rotatably supported at both ends by a developing hopper 9.
Is supplied to the surface of the developing roller 5 which is a toner carrier, and a toner supply roller 6 is provided to scrape off the toner 10 on the developing roller 5 which has not been developed and remains. The toner supply roller 6 has a resistance value of 10 ⁶ formed by forming a conductive foam around a metal shaft 6a.
The shaft 6a is connected to a toner supply bias voltage supply power supply 26 which is a constant voltage power supply.

The developing roller 5 has a single-layer structure in which a metal shaft 5a is used as a base material and silicon rubber as a conductive elastic member is formed on the outer peripheral surface thereof, and its resistance value is about 10 ⁶ Ω. . The rubber hardness of the developing roller 5 is 30 to
The range of 60 degrees is preferable, and the surface roughness is preferably 7 μmRz or less, because the higher the surface smoothness, the more uniform the formation of a thin toner layer can be achieved. In the first embodiment,
The developing roller 5 has a rubber hardness of 40 degrees and a surface roughness of 3 μmRz.
It has become. A developing bias voltage supply power supply 12 which is a constant voltage power supply is connected to the shaft 5 a of the developing roller 5.

The toner 10 is a non-magnetic one-component toner. For example, carbon, wax,
It is composed of a material in which a charge control agent and the like are uniformly dispersed.

The developing roller 5 and the toner supply roller 6 are arranged in contact with each other and have a nip width of, for example, about 2 mm.
a and 6a are rotatably supported respectively. As shown in the drawing, the developing roller 5 and the photoconductor 1 are in contact with each other and rotate in opposite directions, while the developing roller 5 and the toner supply roller 6 are in contact with each other and rotate in the same direction. Has become. Therefore, the developing roller 5 and the toner supply roller 6 are in frictional contact.

The developing roller 5 is in contact with or in proximity to the photosensitive member 1 and has a developing bias voltage power supply 12.
When the toner 10 is transferred and adhered to the portion where the electrostatic latent image is formed on the photosensitive member 1 by the applied bias voltage,
The electrostatic latent image is visualized.

The toner stirring member 11 draws a circular locus as the toner supply roller 6 rotates, and
The toner 10 is prevented from aggregating, and the toner 10 is conveyed toward the toner supply roller 6.

A toner regulating blade 7 is provided in contact with the developing roller 5. This toner regulating blade 7
An elastic metal spring plate member 7a such as a stainless steel plate or a phosphor bronze plate and a toner regulating member 7 which comes into contact with the developing roller 5
b. The toner regulating member 7b is a metal spring plate member 7a.
An elastic member such as urethane rubber or silicone rubber having a rubber hardness of 60 degrees is integrally formed at one end of the member.
Such a toner regulating blade 7 is screwed to a blade holder 8. The toner regulating blade 7 presses the developing roller 5 with, for example, a linear pressure of 80 g / cm.
The toner 10 supplied from the toner supply roller 6 to the developing roller 5 is frictionally charged by the toner regulating blade 7, and a thin toner layer is formed on the outer peripheral surface of the developing roller 5. In the non-magnetic one-component contact developing system as in Embodiment 1, the thickness of the toner layer on the developing roller 5 is preferably in the range of 0.4 to 0.6 mg / cm ² .

Paper 15 is stored in a paper cassette 14 provided at the starting point of the transport path. The paper 15 is fed to a paper cassette 14 by a half-moon shaped paper feed roller 16.
Are fed out to the transport roller 17 one by one. Then, the fed recording sheet 15 is nipped by a pair of transport rollers 17 and transported in the direction of the photoconductor 1 indicated by an arrow A.

The sheet 15 is temporarily stopped and waited, and the sheet 1 is stopped.
In order to make the toner image 5 coincide with the toner image formed on the photoconductor 1, a registration roller 18 is provided on the transport path before reaching the photoconductor 1 in contact with a driven roller. Further, a transfer roller 20 is provided so as to be rotatably supported in contact with the photoconductor 1. The transfer roller 20 is made of a metal such as stainless steel as a base material, and an elastic member is formed in a layer on the outer peripheral surface.

When the toner image reaches the contact portion between the transfer roller 20 and the photosensitive member 1 with the rotation of the photosensitive member 1, the registration roller 18 aligns the toner image with the toner image, and the paper 15 is also brought into contact with the toner image. To reach. At this time, when a high voltage from the transfer bias power supply 24 is applied to the metal shaft 20a of the transfer roller 20 to apply a charge having a polarity opposite to that of the toner 10 to the back surface of the sheet 15, the toner image on the photoconductor 1 Is transferred to

A fixing device 21 including a heat roller 22 having a heat source therein and a pressure roller 23 for sandwiching and conveying the sheet 15 together with the heat roller 22 is provided at a stage subsequent to the conveyance path. Accordingly, the paper 15 on which the toner image has been transferred is sent to the fixing device 21, where the toner image is fixed by pressure and heat by the sandwiching rotation of the heat roller 22 and the pressure roller 23. On the other hand, the photoreceptor 1 after the toner image has been transferred onto the paper 15 has the transfer residual toner scraped off by the cleaning blade 25, and is irradiated with light by the charge eliminator 13 to be neutralized, thereby preparing for the next process.

Using the electrophotographic apparatus configured as described above, the distance L1 between the first corona wire 27a and the first grid plate 27d shown in FIG. 2 is set to 8 mm and 10 mm, and the second corona wire 27b is set. The printing operation was performed by changing the distance L4 between the first grid plate 27e and the second grid plate 27e from 6 mm to 12 mm, and the charging efficiency was evaluated from the charging potential on the surface of the photoreceptor 1 to evaluate charging unevenness from the image. The evaluation was a three-level evaluation of ○, Δ, and ×.

The distance L7 between the side wall of the shield case 27c and the partition plate 27f in the discharge chamber where the first corona wire 27a is stretched, and the second corona wire 27
The distance L8 between the side wall of the shield case 27c and the partition plate 27f in the discharge chamber in which the b is stretched is 30 mm, and the first corona wire 27a and the shield case 27c
L2 between the first corona wire 27a and the partition plate 27f, the distance L5 between the second corona wire 27b and the partition plate 27f, the second corona wire 27b and the side wall of the shield case 27c. Distance L6 is all 15
mm.

The process speed is 200 mm / sec.
c, the peripheral speed of the developing roller 5 was 280 mm / sec, and the peripheral speed of the toner supply roller 6 was 192 mm / sec.

The evaluation results are shown in (Table 1).

[0047]

[Table 1]

As is clear from Table 1, the first corona wire 27a located on the upstream side in the rotation direction of the photosensitive member 1 is provided.
When the distance L4 between the second corona wire 27b located downstream and the grid plate 27e is larger than the distance L1 between the grid plate 27d and the second corona wire 27d, the photosensitive member 1 can be charged sufficiently and uniformly.

In the first embodiment, the photosensitive member 1 is negatively charged by applying a negative current to the first and second corona wires 27a and 27b, but the same applies to the case of positive charging. Can be applied to

(Embodiment 2) The configuration of an electrophotographic apparatus according to Embodiment 2 is the same as that shown in FIGS. 1 and 2, and a description thereof will be omitted. Further, the voltages applied by the power supplies 28 and 29, the wire diameter, the characteristics of the developing roller 5, the toner supply roller 6, the toner regulating blade 7, the toner 10, and the transfer roller 20, the process speed, the peripheral speed of the developing roller 5, and the toner supply The peripheral speed of the roller 6 is the same as in the first embodiment.

Using the electrophotographic apparatus having the above structure, L4, L5 and L6 shown in FIG.
The printing operation was performed by changing L1, L2 and L3 from 13 mm to 17 mm, the charging efficiency was evaluated from the charging potential on the surface of the photoreceptor 1, and the charging unevenness was evaluated from the image. In addition,
Corona discharge device 2 including Embodiment 2 described below
The numerical values of L1 to L8 in 7 are the same as those in the first embodiment unless otherwise indicated. Evaluation is ○, △, ×
Of three-step evaluation. The results are shown in (Table 2).

[0052]

[Table 2]

Next, L1, L2 and L3 shown in FIG. 2 are set to 15 mm, and L4, L5 and L6 are set to 13 mm from 1 mm.
The printing operation was performed with the distance changed to 7 mm, the charging efficiency was evaluated from the charging potential on the surface of the photoconductor 1, and the charging unevenness was evaluated from the image. The evaluation was a three-level evaluation of ○, Δ, and ×. The results are shown in (Table 3).

[0054]

[Table 3]

As apparent from (Table 2) and (Table 3),
In FIG. 1, L2 = L3, L5 = L6, and L1 <L
2. When the relationship of L4 <L5 was satisfied, the photosensitive member 1 was sufficiently and uniformly charged.

In the second embodiment, the photoconductor 1 is negatively charged by applying a negative current to the first and second corona wires 27a and 27b. Applicable.

(Embodiment 3) The configuration of an electrophotographic apparatus according to Embodiment 3 is also the same as that shown in FIGS. 1 and 2, and a description thereof will be omitted. Also, power supplies 28 and 29
Voltage, wire diameter, developing roller 5, toner supply roller 6, toner regulating blade 7, toner 10, transfer roller 20, etc., process speed, developing roller 5,
And the peripheral speed of the toner supply roller 6 are also the same as those in the first embodiment.
Is the same as

Using the electrophotographic apparatus having the above structure, L1 and L4 shown in FIG.
3 and L5 = L6, L7 and L8 are changed from 15 mm to 4
The printing operation was performed by changing the distance to 5 mm, the charging efficiency was evaluated from the charging potential on the surface of the photoconductor 1, and the charging unevenness was evaluated from the image. The evaluation was a three-level evaluation of ○, Δ, and ×. The results are shown in (Table 4).

[0059]

[Table 4]

As is clear from Table 4, the distance L7 between the side wall of the shield case 27c located on the upstream side in the rotation direction of the photosensitive member and the partition plate 27f is made larger than the distance L8 on the downstream side, and L8 <L7. When the relationship of <2 × L8 was satisfied, the photoconductor 1 was sufficiently and uniformly charged.

In the third embodiment, the photoreceptor 1 is negatively charged by applying a negative current to the first and second corona wires 27a, 27b. Applicable.

(Embodiment 4) The configuration of an electrophotographic apparatus according to Embodiment 4 is also the same as that shown in FIGS. 1 and 2, and a description thereof will be omitted. Also, power supplies 28 and 29
, The developing roller 5, the toner supply roller 6,
Characteristics of the toner regulating blade 7, the toner 10, the transfer roller 20, etc., the process speed, the peripheral speed of the developing roller 5,
The peripheral speed of the toner supply roller 6 is the same as that of the first embodiment.

Using the electrophotographic apparatus having the above configuration, L1 and L4 shown in FIG. 2 are 8 mm, L2, L3,
L5 and L6 are 15 mm, and the first corona wire 2
7a diameter φ1 was changed from 40 μm to 100 μm,
The diameter φ2 of the second corona wire 27b is increased from 30 μm to 10
The printing operation was performed by changing the thickness to 0 μm, the charging efficiency was evaluated from the charging potential on the surface of the photoconductor 1, and the charging unevenness was evaluated from the image. The evaluation was a three-level evaluation of ○, Δ, and ×. The results are shown in (Table 5).

[0064]

[Table 5]

As is clear from Table 5, φ1> φ2
When the condition of 40 μm <φ2 <80 μm was satisfied, the photosensitive member 1 was sufficiently and uniformly charged.

In the fourth embodiment, the photoreceptor 1 is negatively charged by applying a negative current to the first and second corona wires 27a, 27b. Applicable.

(Embodiment 5) The configuration of an electrophotographic apparatus according to Embodiment 5 is also the same as that shown in FIGS. 1 and 2, and a description thereof will be omitted. Also, power supplies 28 and 29
Voltage, wire diameter, developing roller 5, toner supply roller 6, toner regulating blade 7, toner 10, transfer roller 20, etc., process speed, developing roller 5,
And the peripheral speed of the toner supply roller 6 are also the same as those in the first embodiment.
Is the same as Further, L1 and L4 shown in FIG.
Is 8 mm and L2, L3, L5 and L6 are 15 m
m.

Using the electrophotographic apparatus configured as described above, the opening ratio R1 of the first grid plate 27d on the upstream side in the rotation direction of the photosensitive member shown in FIG. Aperture ratio R2 of the second grid plate 27e
% To 60% to perform the printing operation.
The charging efficiency was evaluated from the charging potential on the surface, and the charging unevenness was evaluated from the image. The evaluation was a three-level evaluation of ○, Δ, and ×.
The results are shown in (Table 6).

[0069]

[Table 6]

As is clear from Table 6, the aperture ratio of the first grid plate 27d is set to R1, and the second grid plate 27f is set to R1.
Is defined as R2, 0.4 <R2 / R1 <0.8
When the relationship was satisfied, the photosensitive member could be charged sufficiently and uniformly.

In the fifth embodiment, the photoreceptor 1 is negatively charged by applying a negative current to the first and second corona wires 27a and 27b. Applicable.

(Embodiment 6) The configuration of an electrophotographic apparatus according to Embodiment 6 is also the same as that shown in FIGS. 1 and 2, and a description thereof will be omitted. Also, power supplies 28 and 29
Voltage, wire diameter, developing roller 5, toner supply roller 6, toner regulating blade 7, toner 10, transfer roller 20, etc., process speed, developing roller 5,
And the peripheral speed of the toner supply roller 6 are also the same as those in the first embodiment.
Is the same as Further, L1 and L4 shown in FIG.
Is 8 mm and L2, L3, L5 and L6 are 15 m
m. The aperture ratio R1 of the grid plate 27d is 60%, and the aperture ratio R2 of the grid plate 27e is 48%.

When the first corona wire 27a and the second corona wire 27b shown in FIG. 2 are connected in series to the corona current supply power source 28 using the electrophotographic apparatus configured as described above. The printing operation was performed in the case of connecting in parallel with, and the charging efficiency was evaluated from the charging potential on the surface of the photoreceptor 1, and the charging unevenness was evaluated from the image.

As a result, it was clarified that when connected in parallel, the current did not uniformly flow through the two corona wires 27a and 27b, which had an adverse effect on charging efficiency and charging unevenness. And it was confirmed that when both were connected in series, the photosensitive member could be charged sufficiently and uniformly.

In the sixth embodiment, the photosensitive member 1 is negatively charged by applying a negative current to the first and second corona wires 27a and 27b. Applicable.

In the above description, an example in which the corona discharge device according to the present invention is applied to an electrophotographic device has been described.
It can be widely applied to various image forming apparatuses such as an electrostatic recording apparatus.

[0077]

As described above, according to the corona discharge device of the present invention, there is obtained an effective effect that the photosensitive member can be charged sufficiently and uniformly while increasing the peripheral speed of the photosensitive member.

Further, by forming an image forming apparatus using such a corona discharge device, an effective effect that high image quality can be obtained even when a high printing speed is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus using a corona discharge device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a structure of a corona discharge device in the image forming apparatus of FIG.

FIG. 3 is a sectional view showing a conventional corona discharge device.

[Explanation of symbols]

 Reference Signs List 1 photoconductor 27a first corona wire 27b second corona wire 27c shield case 27d first grid plate 27e second grid plate 27f partition plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuhiko Noda 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Toshiro Kitahara 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Keiichi Matsuzaki 1006 Odaka, Kazuma, Kadoma, Osaka Pref.

Claims (7)

[Claims] A metal shield case having a discharge opening opened toward a photoconductor on which an electrostatic latent image is formed; and a metal shield case inside the shield case along a rotation direction of the photoconductor. A partition plate partitioned into two discharge chambers, a first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoreceptor, and an opening of the discharge chamber over which the first corona wire is stretched. A first grid plate attached at a predetermined interval; and an opening of the discharge chamber around which the second corona wire is stretched, wherein the first corona wire and the first grid plate are The second installed at an interval longer than the interval Corona discharge device, characterized in that it comprises a grid plate. 2. A metal shield case having a discharge opening opened toward a photoreceptor on which an electrostatic latent image is to be formed, and a metal shield case inside the shield case along a rotation direction of the photoreceptor. A partition plate partitioned into two discharge chambers, a first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoreceptor in the discharge chamber, and a first grid plate attached to an opening of the discharge chamber where the first corona wire is stretched. And a second grid plate attached to an opening of the discharge chamber on which the second corona wire is stretched, wherein the distance between the first corona wire and the first grid plate is L1, the first corona wire and the seal The distance between the side wall of the case is L2, the distance between the first corona wire and the partition plate is L3, the distance between the second corona wire and the second grid plate is L4, the second corona wire L2 = L3, L5 = L6, and L1 <L, where L5 is the distance between the second corona wire and the side wall of the shield case.
2. Corona discharge devices, each of which is arranged so as to satisfy a relationship of L4 <L5. 3. A shield case made of metal having a discharge opening opened toward a photoconductor on which an electrostatic latent image is formed, and a metal case inside the shield case along a rotation direction of the photoconductor. A partition plate partitioned into two discharge chambers, a first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoreceptor in the discharge chamber, and a first grid plate attached to an opening of the discharge chamber where the first corona wire is stretched. And a second grid plate attached to the opening of the discharge chamber on which the second corona wire is stretched, wherein the shield in the discharge chamber on which the first corona wire is stretched Distance between the side wall of the case and the partition plate The L
7. When the distance between the side wall of the shield case and the partition plate in the discharge chamber in which the second corona wire is stretched is L8, the relationship of L8 <L7 <2 × L8 is satisfied. A corona discharge device, wherein 4. A metal shield case having a discharge opening opened toward a photoconductor on which an electrostatic latent image is to be formed, and a metal case inside the shield case along a rotation direction of the photoconductor. A partition plate partitioned into two discharge chambers, a first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoreceptor in the discharge chamber, and a first grid plate attached to an opening of the discharge chamber where the first corona wire is stretched. And a second grid plate attached to the opening of the discharge chamber where the second corona wire is stretched, wherein the diameter of the first corona wire is φ1, and the second corona wire is Where φ1> φ2 and 4 μ
A corona discharge device wherein the diameters of the first and second corona wires are set so as to satisfy a relationship of m <φ2 <80 μm. 5. A metal shield case having a discharge opening opened toward a photoreceptor on which an electrostatic latent image is formed, and a metal case inside the shield case along a rotation direction of the photoreceptor. A partition plate partitioned into two discharge chambers, a first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoreceptor in the discharge chamber, and a first grid plate attached to an opening of the discharge chamber where the first corona wire is stretched. And a second grid plate attached to an opening of the discharge chamber on which the second corona wire is stretched, wherein an opening ratio of the first grid plate is R1, and the second grid is When the aperture ratio of the plate is R2, 0.4 <R / R
A corona discharge device wherein the aperture ratios of the first and second grid plates are set so as to satisfy a relationship of 1 <0.8. 6. A metal shield case having a discharge opening opened toward a photoreceptor on which an electrostatic latent image is formed, and a metal case inside the shield case along a rotation direction of the photoreceptor. A partition plate partitioned into two discharge chambers, a first corona wire stretched in the width direction of the photoconductor in the discharge chamber on the upstream side in the rotation direction of the photoconductor, and a downstream side in the rotation direction of the photoconductor. A second corona wire stretched in the width direction of the photoconductor and electrically connected in series with the first corona wire, wherein the first corona wire is stretched. A first grid plate attached to an opening of the discharge chamber; and a second grid plate attached to an opening of the discharge chamber around which the second corona wire is stretched. Corona discharge device. 7. An image forming apparatus using the corona discharge device according to claim 1, 2, 3, 4, 5, or 6.