JPH0375760A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To increase the corona irradiation density of an opening without increasing the total current by forming the cross section of a charge wire in such a manner that the length in the diameter direction of a photosensitive body is shorter than a length perpendicular to that length. CONSTITUTION:The charge wire 32 is stretched across a casing 30 so as to be parallel with the photosensitive body 14. The cross section of the wire 32 is formed into an almost oval by making the length L, which is perpendicular to the length (l), longer than the length (l) in the diameter direction of the photosensitive body 14. When a high voltage is applied to the wire 32, the corona irradiation density of the flat part 32a on the side of the length L is increased while it is reduced on the side of the length (l). Since the side of the length L of the wire 32 faces the opening 30a of the casing 30, the corona irradiation density on the side of the opening 30a, shown by an arrow A, is increased. Thus, the total current can be reduced and harmful effects caused by corona discharge can be eliminated, by only replacing with the wire 32.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to electrophotographic devices such as printers, copiers, and facsimile machines that use lasers to record on paper using electrophotographic processes such as charging, exposure, development, transfer, and fixing. Regarding.

Conventionally, in this type of device, the charging wires of the charging section, transfer section, etc. were enclosed in a casing, except for the opening facing the photoconductor, and ran parallel to the photoconductor. Then, a high voltage is applied to the charge wire, and the surface of the photoreceptor is charged by corona discharge, for example, at the charging section, and the toner image on the photoreceptor is transferred to paper at the transfer section.

However, conventionally, for the total current flowing through the charge wire,
Sufficient charging due to corona discharge could not be obtained. This is because the cross-sectional shape of the charge wire is round (circular), so corona discharge occurs evenly around the entire circumference, and the generated corona ions are grounded from the casing surrounding the charge wire.
This is because only the corona ions emitted from the opening of the casing are utilized.

By the way, ozone is generated during corona discharge, and the ozone causes various problems, and there is also the problem that dust in the air is attracted to the charge wire, causing uneven charging and uneven image density.

Therefore, increasing the total current flowing through the charge wire may aggravate the adverse effects caused by the corona discharge.

Therefore, in conventional devices, without increasing the total current flowing through the charge wire, an insulator such as insulating tape, mylar, or insulating paint is provided on both sides of the opening of the casing, and the insulator reflects the corona ions and emits the corona ions. The density is intentionally changed to increase the corona radiation density at the aperture.

However, with conventional equipment, insulating tape, Mylar, and insulating paint are applied to both sides of the casing opening, which is a hassle.

Therefore, the purpose of this invention is to eliminate the troublesome work of installing insulating tape or mylar on both sides of the opening of the casing or applying insulation coating, and to eliminate corona discharge at the opening without increasing the total current flowing through the charge wire. The goal is to increase density.

In order to achieve the above object, the present invention provides an electrophotographic apparatus in which a wire is passed in parallel with a photoreceptor.
The charge wire is characterized in that the cross-sectional shape of the charge wire is longer in the direction perpendicular to the radial direction of the photoreceptor than in the radial direction of the photoreceptor.

Then, the corona radiation density is increased on the side of the charge wire facing the photoreceptor.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 schematically shows the entire internal mechanism of a laser printer which is an embodiment of the present invention. The code 10 in the figure is
This is the main body of the device. A paper feed tray 11 is detachably attached to the right side of the apparatus main body 10 in the figure. Paper 12 is stored in the paper feed tray 11 . The apparatus main body 10 also includes a photoreceptor 14, a charging section 15, an optical writing section 16, a developing section 17, a transfer section 18. It includes a cleaning section 19, a fixing section 20, and the like. and.

As the photoreceptor 14 rotates, its surface is uniformly charged by a charging unit 15, a video signal sent from the outside is electronically converted by an optical writing unit 16, and the electrostatic latent is scanned using a laser beam. An image is formed, and this electrostatic latent image is visualized in a developing section 17 to form a toner image.

On the other hand, the paper 12 in the paper feed tray 11 is transferred to the paper feed roller 21.
Then, the toner image is transferred to the paper 12 by the transfer section 18, and the paper 12 is separated from the photoconductor 14 by a separation section (not shown).

It is transported and sent to the fixing section 20. Then, in the fixing unit 20, the hot roller 23 and the pressure roller 24 apply heat and pressure to fix the paper, and then the paper is selectively sent out to the paper discharge tray 27 or 28 by the paper discharge rollers 25 and 26 and stacked thereon.

By the way, in the laser printer of the embodiment, the transfer section 1
8 is specifically constructed as shown in FIG. That is, the casing 30 of the transfer unit 18 is formed by bending a sheet metal into a U-shaped cross section to enclose three sides and provide an opening 30a on the other side to form an elongated box shape. The casing 30
A holder member 31 is fixed to both ends in the length direction. The holder member 31 is made of an insulating material and is formed into a block shape.

A charge wire 32 is stretched in the length direction of the casing 30, and the casing 30 is connected to a third
Attach the charge wire 32 to the photoreceptor 14 as shown in the figure.
As shown in FIG. 2, the cross-sectional shape of the charge wire 32 that runs parallel to the photoreceptor 14 is longer in the direction perpendicular to the photoreceptor 14 than in the radial direction;
Form into a roughly oval shape.

When a high voltage is applied to the charge wire 32, the corona radiation density at the flat portion 32a on the length L side becomes high, and the corona radiation density on the length L side in the direction perpendicular to the flat portion 32a becomes low. Since the length L side of the charge wire 32 is directed toward the opening 30a of the casing 30, the corona radiation density on the opening 30a side indicated by arrow A becomes high.

Although the charge wire 32 described above has an oval cross-sectional shape, it may have various cross-sectional shapes as shown in FIGS. 3(a) to (h).

In FIG. 3, the charge wire 32 shown in (H) is
It is a tape-like thin plate. Also, in each figure in Figure 3,
Arrow A indicates the side with higher corona radiation density.

In the above-described embodiment, a laser printer was described in which the cross-sectional shape of the charge wire 32 of the transfer section 18 was formed so that the length L in the direction perpendicular to the radial direction of the photoreceptor was longer than the length in the radial direction of the photoreceptor. The charge wire 34 of the charging part,
A laser printer may be constructed by similarly configuring the charge wire of the separating section that separates the paper after transfer from the photoreceptor.

From the above, according to this invention, there is no need to apply insulating tape, Mylar, or insulating paint to the opening of the casing.
The corona radiation density at the opening can be increased, and sufficient charging can be achieved.

Also, by simply replacing the traditional charge wire.

The total current flowing through the charge wire can be lowered.

Therefore, the adverse effects caused by corona discharge are improved.

For example, it is possible to reduce the generation of ozone and the collection of dust on the surface of the charge wire.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a transfer section provided in a laser printer which is an embodiment of the present invention, FIG. 2 is a schematic diagram of a part of the charge wire and photoreceptor, and FIG. 3 is a diagram showing the other parts of the charge wire. In this embodiment, (a) to (h) are sectional views of the charge wire. FIG. 4 is an overall schematic diagram of the internal mechanism of the laser printer. 10... Apparatus body 14... Photoreceptor 15... Charging section 18... Transfer section

Claims (1)

[Scope of Claims] In an electrophotographic apparatus in which a charge wire is passed in parallel to a photoreceptor, the cross-sectional shape of the charge wire is formed such that a length in a direction perpendicular to the radial direction of the photoreceptor is longer than a length in a radial direction of the photoreceptor. This is an electrophotographic device.