JPH08185012A - Contact charger - Google Patents

Abstract

PURPOSE: To simplify the charger and to eliminate an electrical noise by providing a power source to impress a voltage between a dielectric and an electrode and a means to ionize the atmosphere in the vicinity of the discharge part of the electrode to the charger. CONSTITUTION: A voltage is impressed between the first electrode 2 and second electrode 4 of a charging member 1 from a first power source 5; an electric discharge is generated between the tips of the first electrode 2 and second electrode 4, and the atmosphere in the vicinity of the charging part of the electrode is ionized. A dielectric layer 9 is applied on a dielectric 8 as an image carrier 7. The dielectric 8 is brought into contact with the second electrode 4 and relatively moved, a DC voltage is impressed between the dielectric 8 and the second electrode 4 from a second power source 6, and the surface of the dielectric layer 9 has a surface potential almost equal to the potential applied on the second electrode 4. Consequently, the charger is simplified, an AC power source is not needed, and the problem such as an electrical noise caused by an AC power source is solved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for uniformly charging a dielectric surface by bringing a charging member into contact with a dielectric surface of an image forming apparatus and applying a voltage between the charging member and the dielectric. Is.

[0002]

2. Description of the Related Art Conventionally, contact charging of a dielectric surface of an image carrier of an image forming apparatus is disclosed in JP-A-63-149669.
JP-A 1-267667 and Japan Hardc
As described in detail in pages 37 to 40 of the opy'90 paper, a charging roller having a conductive resin and a resistance film on a metal shaft has a DC component of -620V and an AC frequency of 10V.
A method of superposing an amplitude of 1500 V (Vp-p, peak-to-peak voltage) at 00 Hz to uniformly charge the dielectric layer has been put into practical use.

[0003]

However, the above-mentioned conventional example has the following drawbacks because it requires an AC component and a high voltage.

1) Since an expensive AC power source is required, the device cost increases.

2) Since electric noise (radio waves) is generated due to the high-voltage AC component, a sufficient radio wave shield is required.

3) Since a high voltage is applied between the dielectric and the contact charging member, when there is a partial defect in the dielectric layer or the contact charging member, a spark discharge or a pinhole pattern during image formation appears. There is a risk of being caught.

4) The contact charging structure is complicated and expensive as described above.

5) Since an electric potential of the above-mentioned AC frequency appears on the surface of the dielectric after charging, at the time of image formation, an optical pattern is formed according to the image pattern of a commonly known laser optical system, LED, etc. Then, interference fringes are generated between the AC components of those optical systems.

An object of the present invention is to solve the above problems.

[0010]

In order to solve the above problems, the first invention of the present application is directed to an electrode which moves relative to a dielectric while contacting the dielectric, and a voltage is applied between the dielectric and the electrode. And a means for ionizing the atmosphere near the discharge part of the electrode.

A second invention is the same as the first invention,
The ionizing means is a second electrode provided in the vicinity of the electrode, and a voltage is applied between the electrode and the second electrode.

A third invention is characterized in that, in the first or second invention, at least one of the electrode or the second electrode tip has a semi-insulator.

A fourth invention is characterized in that, in the first to third inventions, the tip of the second electrode is covered with an insulator and an AC voltage is applied.

[0014]

【Example】

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
An example of the image forming apparatus will be described with reference to FIG. FIG. 1 is a view best showing the features of the present invention. In FIG. 1, the charging member 1 is applied with a voltage from a first power supply 5 between a first electrode 2 and a second electrode 4, Is discharged at the tips of the electrode 2 and the second electrode 4, and the atmosphere near the electrode discharge is ionized. A dielectric layer 9 is coated on the conductor 8 as the image carrier 7. By applying a direct current voltage from the second power source 6 between the conductor 8 and the second electrode 4 while the dielectric layer 9 and the second electrode 4 are in contact with each other and relatively moved, The surface has a surface potential that is substantially equal to the potential applied to the second electrode 4.

A description will be given below using specific numerical values. The charging member 1 uses stainless steel foil with a thickness of 20 μm for each of the first electrode 2 and the second electrode 4, and the insulating layer 3 has a thickness of 3 μm.
0 μm polyimide was used. An aluminum cylinder having a diameter of 30 mm is used as the conductor 8 as the image carrier 7, and a photosensitive material such as an organic semiconductor (hereinafter referred to as OPC) zinc oxide, selenium, or amorphous silicon is applied or vapor-deposited as the dielectric layer 9. To do.

In this apparatus, OPC is used, driven and rotated at 100 mm / sec in the direction of the arrow, and the charging member 1 is moved to the image carrier 7 at an angle α of 0 ° to approximately 90 ° or the voltage of the first electrode and the second electrode. The polarity can be changed from 90 ° to approximately 180 °, but in this embodiment, the angle was selected to be 45 °.
Now, as shown in FIG. 1, a voltage of -1250 V is applied to the first electrode 2,
When a voltage of -600V is applied to the second electrode 4, the surface of the image carrier 7 is uniformly charged to about -580V.

Next, an electric signal according to an image pattern is applied to the laser diode 10 to form an image light L1 and the polygon mirror 1 is rotated by a high speed motor 11.
When the image bearing member 7 is reflected by 2 and irradiated onto the image bearing member 7, an electrostatic latent image is obtained on the image bearing member 7. Since the amount of light irradiation light at this time varies depending on the type of the image carrier 7, it is preferable to select about -60 to -100V.

In the developing device 13, conventionally known means such as one-component jumping development, two-component magnetic brush development, and cascade development are used. In this apparatus, one-component jumping development is used, and in order to perform so-called reversal development in which a developer (hereinafter referred to as toner) adheres to the position where light is irradiated, the potential is almost equal to the potential of the surface of the image carrier 7. Was developed by applying a voltage of -500V. An alternating voltage may be superimposed on this voltage.

The toner image obtained on the image carrier 7 is transferred onto the transfer paper P by the action of the transfer roller 14. The transferred toner is fixed or fixed on the transfer paper by means of heating, pressurizing, etc., not shown.

The toner remaining on the image carrier 7 is removed by the cleaning device 15, and the same process is repeated.

According to the above-mentioned embodiment, the device can be simplified, the radio wave shield and the like are not required, and it is resistant to image defects due to defects such as pinholes and scratches in the dielectric layer. In an image forming apparatus such as a beam printer, it is possible to prevent generation of interference fringes and the like, and it is possible to prevent generation of charging noise as compared with AC voltage application contact charging.

(Other Embodiments) FIG. 3 shows another embodiment of the present invention. In the first embodiment of the present invention described with reference to FIGS. 1 and 2, spark discharge or the like occurs when electric field concentration occurs due to scratches, stains or the like on the discharge surfaces of the first electrode 2 and the second electrode 4. Failure may occur.

In order to solve the above problem, in the embodiment shown in FIG. 3, the semi-insulators 16 · 10 ⁴ to 10 ⁴ are attached to the tip of the second electrode 4.
The insulating member 16 is formed by applying a volume resistivity of about 10 ¹² Ω · cm to about 20 μm.

In this embodiment, in addition to the same effect as the first embodiment, the above-mentioned drawback can be eliminated.

Of course, it has been found that similar results can be obtained by performing the same treatment on the first electrode 2 as well.

As the material of the semi-insulator 16, amorphous silicon, silicon carbide, amorphous ceramics, zinc sulfide sinter, boron nitride, silicon nitride, zinc sulfide, or carbon in resin (including resin such as rubber) is used. It may be composed of dispersed materials.

FIG. 4 shows still another embodiment of the present invention. In this embodiment, the first electrode 2 described in the first embodiment is covered with the insulator 2A, and the first electrode 2 and Similar effects can be obtained by applying an AC voltage between the second electrodes 4 from the first power supply 5 '. In this case, for example, about 1200 Vpp may be applied. All the combinations of the configurations of FIGS. 1 to 4 described above are possible.

Another embodiment of the present invention is shown in FIG. 5, and as shown in the figure, it is composed of a second electrode 4 and an insulator 3, and energy such as ultraviolet rays or X-rays or electromagnetic waves capable of ionizing air. May be irradiated to ionize between the second electrode 4 and the dielectric 7.

Also in each of the embodiments shown in FIGS.
The same effect as that of the first embodiment can be obtained.

[0030]

As described above, according to the present invention,
Since the dielectric layer and the charging member are in contact with each other while being moved, and only the DC voltage is applied, 1) the device can be simplified, 2) radio wave shield is not required, 3)
Strong against image defects such as pinholes and scratches that are defects in the dielectric layer 4) In particular, it is possible to prevent interference fringes in image forming devices such as LED lasers and beam printers 5) AC voltage application contact As compared with charging, it is possible to achieve effects such as preventing the generation of charging noise.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a basic configuration of the present invention.

FIG. 2 is a sectional view illustrating a first embodiment of the present invention.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing still another embodiment of the present invention.

FIG. 5 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Charging member 2 ... 1st electrode 3 ... Insulating layer 4 ... 2nd electrode 7 ... Dielectric ...

Claims (4)

[Claims] 1. A method comprising: an electrode that relatively moves while being in contact with a dielectric; a power supply for applying a voltage between the dielectric and the electrode; and a means for ionizing an atmosphere near the discharge part of the electrode. Contact charging device. 2. The contact charging device according to claim 1, wherein
The contact charging device, wherein the means for ionizing is a second electrode provided in the vicinity of the electrode, and a voltage is applied between the electrode and the second electrode. 3. The contact charging device according to claim 1, wherein at least one of the electrode and the tip of the second electrode has a semi-insulator. 4. The contact charging device according to claim 2, wherein the tip of the second electrode is covered with an insulator and an AC voltage is applied.