JP2002296874A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device internally equipped with an electrifying device capable of restraining the producing amount of produced ozone and a sound pressure level by applying AC voltage to a discharge wire coated with dielectric substance. SOLUTION: In this image forming device having the electrifying device constituted so that the potential of a photoreceptor is controlled by applying the AC voltage to the discharge wire coated with the dielectric substance and also applying DC voltage having a specified polarity to a potential control plate provided near the discharge wire, the thickness of the dielectric substance with which the discharge wire is coated is within 30 μm to 50 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The present invention relates to an image forming apparatus such as a copying machine or a printer having a charging device for performing corona discharge by applying a voltage.

[0002]

2. Description of the Related Art Generally, a corona charger provided in an image forming apparatus such as a copying machine or a printer of an electrophotographic type has a shield member formed by a side plate and a back plate, and a band electrode is provided in the shield member. Are arranged by arranging discharge wires constituting the above. Further, in a state where the discharge wire is attached to a predetermined location in the apparatus, a discharge opening of the shield member is provided so as to face the drum-shaped or belt-shaped photoconductor surface. In use, a high voltage is applied to the discharge wire. When applied, a corona discharge is generated and charge is applied to the photoreceptor surface.

[0003] However, the above-mentioned discharge wires do not have sufficient durability, so that there is often an inconvenience that they have to be replaced.

As a measure for improving the durability, a dichrotron method in which the surface of a discharge wire is coated with a dielectric substance such as glass and an AC voltage is applied to the discharge wire has been proposed.

According to Japanese Patent Publication No. 60-18060, the thickness of a dielectric substance is described as 51 μm to 254 μm.

[0006]

However, the discharge wire coated with the above-mentioned dielectric substance has a large thickness of the dielectric substance due to the necessity of maintaining the insulating property, so that the discharge voltage has to be increased. A problem arises in that the amount of ozone generated and the discharge noise when an AC voltage is applied increase.

An object of the present invention is to provide an image forming apparatus in which a charging device for solving the above problem is provided.

[0008]

An AC voltage is applied to a discharge wire coated with a dielectric substance, and a DC voltage having a predetermined polarity is applied to a potential control plate provided in the vicinity of the discharge wire. An image forming apparatus having a charging device configured to control an electric potential of a body, wherein the image forming device has a charging device in which a thickness of a dielectric substance covering the discharge wire is in a range of 30 μm to 50 μm. Forming equipment.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The description in the present application does not limit the technical scope of the claims and the meaning of terms.

FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus including a printer. FIG. 2 is a schematic diagram showing a cross-sectional configuration of a charging device of a dicotron type.

FIG. 3 is a graph showing a comparison of the ozone generation amount with respect to the discharge time of the discharge wire diameter.

FIG. 4 is a graph showing a comparison between the diameter of the discharge wire and the sound pressure level. In FIG. 1, reference numeral 10 denotes a photoreceptor as an image forming body, 11 denotes a charging device, 12 denotes an exposure optical system as image writing means, 13 denotes a developing device, and 14 denotes a cleaning device for cleaning the surface of the photoreceptor 10. , 15 is a cleaning blade, 16 is a developing sleeve, 17 is a transfer device as transfer means, 18 is a separation pole for separating the transfer material P from the photoconductor 10, and 19 is a separation preventing the transfer material P from winding around the photoconductor 10. They are nails. Photoconductor 10, charging device 11, exposure optical system 12, developing device 13, transfer pole 17, separation pole 18,
The separation claw 19 and the cleaning device 14 constitute the image forming unit 1.

The photoreceptor 10 is formed by forming a photosensitive layer such as a conductive layer, an a-Si layer or an organic photosensitive layer (OPC) on the outer periphery of a cylindrical metal substrate formed of, for example, an aluminum material. Is rotated clockwise as indicated by the arrow in FIG.

Reference numeral 20 denotes a conveyor belt having a plurality of holes, 21 denotes a driving roller, 22 denotes a driven roller, and 23 denotes a suction box. It is connected to a duct, a suction fan, and the like shown in the figure, and has a function of sucking the transfer material P onto the traveling conveyor belt 20. The transport unit 2 is formed by the transport belt 20, the driving roller 21, the driven roller 22, the suction box 23, and the like.

Numeral 30 is a paper cassette, 31 is a feed roller, 32 and 33 are transport rollers, 34 is a timing roller, 35 is a manual feed roller, 36 is a manual feed tray, 40 is a fixing device, 41 is a heat fixing roller, 42 Denotes a pressure roller and 70 denotes an image reading unit.

Next, an image forming process will be described with reference to the drawings. When a drive motor (not shown) starts rotating at the start of image formation (recording), the photoconductor 10 rotates clockwise as indicated by an arrow. At the same time, the charging device 11 starts applying a potential to the photoconductor 10.

On the photoreceptor 10 after the potential is applied,
Image writing of an electric signal corresponding to image data from the image reading device 70 is started through the exposure optical system 12,
An electrostatic latent image corresponding to the original image is formed on the surface of the photoconductor 10, and the electrostatic latent image is reversely developed by the developer conveyed by the developing sleeve 16 of the developing device 13, and a toner image (visible image) Becomes

On the other hand, the transfer material P is sent out from a paper cassette 30 by a feed-out roller 31,
And is conveyed to the timing roller 34, sent out by the drive of the timing roller 34, and
Synchronized with the upper toner image, the transfer pole 17 and the photoconductor 10
To the area between Even in the case of manual paper feed, the transfer material P on the manual paper feed tray 36 is
5, is conveyed to the timing roller 34 via the conveying roller 33, is sent out by the driving of the timing roller 34, is synchronized with the toner image on the photoconductor 10, and is formed between the transfer pole 17 and the photoconductor 10. It is fed to the area between.

The toner image is transferred onto the transfer material P by a transfer pole 17 to which a voltage having a polarity opposite to that of the toner is applied.

Thereafter, the photoreceptor 10 continues to rotate, is cleaned by the cleaning device 14, and is directed to the next image formation.

On the other hand, the transfer material P carrying the toner image thereon is
The photoreceptor 1 is subjected to the charge removal operation by the AC voltage at the separation pole 18 and
The attraction force with zero is weakened, and the photosensitive member 10 is separated from the photosensitive member 10 by curvature. There is a concern that the transfer material P may be wrapped around the photoreceptor 10 due to environmental humidity and the like, so that the separation claw 19 is provided.

The separated transfer material P is sent to the conveying means 2, sucked by the conveying belt 20 by the suction box 23, and conveyed to the fixing device 40. Thereafter, the transfer material P is applied with heat and pressure while being nipped and conveyed in a nip portion T between the heat fixing roller 41 and the pressure roller 42, so that the toner image is fused and fixed on the transfer material P.

Next, a description will be given of a discharge (dichorotron method) generated by applying an AC voltage to a discharge wire coated with a dielectric substance.

As described above, when the thickness of the dielectric material is increased and the diameter is increased, the discharge voltage must be increased, and accordingly, the amount of generated ozone and the AC voltage increase.
The problem of harshness at the time of applying a voltage leads to the generation of discharge noise that gives an unpleasant feeling.

In order to solve the above problem, it is necessary to maintain a uniform charge state on the surface of the photoreceptor by securing a certain amount of generated ions while maintaining the insulating property of the discharge wire coated with the dielectric substance. This is made possible by making the thickness of the dielectric substance as small as possible and applying a smaller discharge voltage.

Next, an experiment using a charging device as shown in FIG. 2 will be described. In FIG. 1, the charging device 11 includes a discharge wire 111 coated with a dielectric material 114 made of glass, a side plate 112, a back plate 113, and the like. Side plate 112 and back plate 1
Reference numeral 13 applies a DC control voltage E and serves as a potential control plate for controlling the potential of the photoconductor 10. Dielectric substance 11
The thickness t of 4 is desirably 30 μm to 50 μm.

In this embodiment, the amount of ozone generated when the photoreceptor 10 is discharged as a single unit in a box using a dummy drum made of an aluminum tube and combined with the charging device 11 is described. , Sound pressure level, 3 different thickness
Measurements were made on various types of discharge wires.

As a condition for obtaining a good image, it is necessary that a current of a predetermined value or more flows through the photosensitive drum 10 as the dummy drum. Now, the experimental conditions are such that the constant current I is 235 μA for the measurement of the amount of generated ozone and 250 μA for the measurement of the sound pressure level, and the control voltage E to the potential control plate is −
800V, distance H between photoconductor 10 and coated discharge wire
Is set to 3 mm, and the distance D between the side plate 112 and the coated discharge wire is set to 3 mm.
= 220 μm, a = 100 μm, t = 60 μm),
(B = 156 μm, a = 60 μm, t = 48 μm),
(B = 128 μm, a = 60 μm, t = 34 μm), the respective VI characteristics and the ozone concentration ratio were confirmed (where a is the diameter of the element wire of the discharge wire 111, b is the diameter of the dielectric substance 114). , T indicate the thickness of the dielectric substance 114, and the material of the dielectric substance 114 is glass.

The result of the measurement, a constant current I = for obtaining the 235Myuei, necessary applied voltage and generating ozone concentration ratio of the discharge wires of the three, compared voltage 13 kV _PP, concentration ratio 1, the voltage 12. 6 kV _PP , concentration ratio 0.91,
Is a graph as shown in FIG. 3 at a voltage of 12.2 kV _PP and a concentration ratio of 0.83 (the vertical axis is the amount of generated ozone, and the horizontal axis is the discharge time). Further, regarding the sound pressure level, a constant current = 250
A graph as shown in FIG. 4 was obtained when μA was used (the vertical axis represents the sound pressure level, and the horizontal axis represents the diameter of the dielectric substance).

From the above results, the sound pressure level and ozone generation amount of the improved type in which the diameter a of the wire of the discharge wire 111 and the thickness t of the dielectric substance 114 are reduced within a limited range are as follows:
It can be seen that the thickness t of the dielectric material is suppressed to be lower than that of the unmeasured type in which the thickness is 60 μm.

[0032]

According to the present invention, it is possible to provide an image forming apparatus in which a charging device using an improved discharge wire capable of suppressing the ozone generation amount and the sound pressure level is provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus including a printer.

FIG. 2 is a schematic diagram illustrating a cross-sectional configuration of a charging device of a dicotron type.

FIG. 3 is a graph showing a comparison of an ozone generation amount with respect to a discharge time of a discharge wire diameter.

FIG. 4 is a graph showing a comparison between a discharge wire diameter and a sound pressure level.

[Explanation of symbols]

 Reference Signs List 10 photoconductor 11 charging device 111 discharge wire 112 side plate 113 backplate 114 dielectric material

Claims (1)

[Claims] 1. A discharge wire coated with a dielectric material is provided with A
An image forming apparatus having a charging device configured to control the potential of the photoconductor by applying a C voltage and applying a DC voltage of a predetermined polarity to a potential control plate provided near the discharge wire; An image forming apparatus comprising: a charging device in which a thickness of a dielectric material covering the discharge wire is in a range of 30 μm to 50 μm.