JPH01973A - electrophotographic equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to electrophotographic devices such as printers and copying machines that utilize an electrophotographic process.

[Conventional technology]

Laser printers that use an electrophotographic process apply a corona discharge charge generated by a main charger to a centrally located photoreceptor drum, which is then exposed to light, and the latent image formed by this exposure is developed. The toner is developed using a device, and the resulting visible image is further transferred onto paper using a transfer charger, and this is fixed to give a permanent visible image. Therefore, applying a uniform potential on the surface of the photoreceptor with the main charger is an important factor in determining the quality of the permanent visible image.

This 4! The amount of F charge can be changed by changing the current applied to the charging wire and the distance between the charging wire and the photoreceptor.

By the way, as shown in FIGS. 2(a) and 2(b), a conventional charger has insulators 4a at both ends of a long and narrow shield case 1.
.

Electrical terminals 5a and 5b are attached via the terminal 4b, and two charged wires 2 and 3 for corona discharge are stretched in parallel between the electrical terminals 5a and 5b, and the support height of the charged wires 2 and 3 is The distance between the charging wire and the photoreceptor was varied in the length direction by making the electric terminals 5a and 5b have different heights, and by making both charging wires tilt in the same direction.

[Problem that the invention seeks to solve]

The above-mentioned conventional charger is effective when the potential amount varies regularly in the longitudinal direction in the relationship between the photoreceptor drum 7 and the charging wire shown in FIG. As shown in b), the surface potential of the photoreceptor drum 7 is often the same at the front and rear ends and is higher at the center, and in such cases it has not been possible to correct it.

Since a charging wire is originally stretched long, there is a difference in charging efficiency between both ends and the center, and the potential at the center is generally high as described above.

An object of the present invention is to provide an electrophotographic apparatus that enables uniform charging over the entire surface of a photoreceptor.

[Means for solving problems]

The present invention provides an electrophotographic apparatus having a charger that energizes a 41F electric wire along the surface of a photoreceptor and charges the surface of the photoreceptor with static electricity through corona discharge. Set the installation interval between the two ends to be wider than the installation interval at both ends.

This electrophotographic device is characterized by:

〔Example〕 Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIGS. 1(a) and 1(b), electrical terminals 5a and 5 are connected to both ends of the shield case 1 via insulators 4a and 4b.
Two charged wires 2 for corona discharge are inserted into the longitudinal grooves 6 of the insulators 4a and 4b and placed inside the case F.
, 3, one end 2a, 3a of which is hooked to the electrical terminal 5a,
Other end 2b.

: 3b is hooked to the electric end 7-5b via the spring 8.

In this embodiment, one of the two charged wires 2 and 3 is supported in the groove 6 through the insulator 4a on the side of the electric terminal 5a.
To install it, an adjustment screw 9a is attached to adjust the height position, and the height position of the other charging wire 2 is similarly adjusted to the insulator 4b on the electric terminal 5b side. 14 setting screw 9b is attached.

In the present invention, as shown in FIG. 1(b), one charged wire 2
Fix the end 2a on the electrical terminal 5a side of the electrical terminal 5b.
Push up the end 2b of the charged wire 2 on the side with the adjusting screw 9b, fix the end 3b of the other charged wire 3 on the electrical terminal 5b side, and push the end 3a of the charged wire 2 on the electrical terminal 5a side with the adjusting screw 9
Push up with a, wire both charged wires 2 and 3 in a cross pattern, and connect the fourth
As shown in FIG. 2B, one end 2b of the charging wire 2 is brought close to the surface of the photoreceptor 7, and the other end 3b of the charging wire 3 is brought closer to the surface of the photoreceptor 7.

In other words, by bringing the opposite ends 2b and 3a of the charged wires 2 and 3 closer to the photoreceptor 7 and crossing them relatively, the distance between the center of both the charged wires 2 and 3 and the photoreceptor 7 is set by a certain amount. Set to A. On the other hand, the ends 2 of the charged wires 2 and 3
In b and 3b, the end 2b of the charging wire 2 is closer to the surface of the photoreceptor 7 than the end 3b of the charging wire 3, and the distance between the end 2b of the charging wire 2 and the surface of the photoreceptor is A-x. The distance between the end 3b of the charging wire 3 and the surface of the photoreceptor is set to +X. In this case, since the charging efficiency is determined by the charging line set at A-x, the charging efficiency due to corona discharge is better than at the center of the charging line. In addition, charged wires 2 and 3
end 2a.

3a, the end 3a of the charging wire 3 is closer to the surface of the photoreceptor than the end 2a of the charging wire 2, and the same thing can be said.

In this way, as shown in FIG. 4(a), the charged wire 2.
In order to set the installation interval A at the center of 3 with respect to the surface of the photoreceptor to be wider than the installation interval A-x at both ends 2b and 3a,
It becomes possible to uniformly charge the entire surface of the photoreceptor by corona discharge as shown in FIG. 4(b).

In the embodiment, there are two charging wires, but there may be two or more charging wires. Further, in the embodiment, the heights of both the front and rear can be changed, but even if the height of one is adjustable only on the front side and the other one only on the back side, the same effect can of course be obtained. If there is only one charged wire, the same effect can be obtained by adjusting the height of the center using an insulating spacer at the center.

〔Effect of the invention〕

As explained above, the present invention includes a charger for charging a photoreceptor in an electrophotographic printer and a copying machine,
The distance between the charging wire stretched on the charger and the surface of the photoreceptor can be adjusted at the center and both ends of the charging wire in the longitudinal direction to correspond to the optimal surface potential of the photoreceptor. This has the effect of making it possible to uniformly charge the particles, thereby increasing the quality of the print images finally obtained from printers and copying machines.

[Brief explanation of drawings]

FIG. 1(a) is a cross-sectional view showing the charger in the present invention,
Figure 1 (b) is a cross-sectional view along the same line, Figure 2 (a) is a cross-sectional view showing the conventional example, Figure 2 (b) is a longitudinal cross-sectional view of the same, and Figure 3 (a).
is a schematic diagram showing a conventional example, FIG. 3(b) is a characteristic diagram on the surface of a photoreceptor in the conventional example, FIG. 4(a) is a schematic diagram showing the present invention, and FIG. 4(b) is a characteristic diagram of the present invention. FIG. 3 is a characteristic diagram on the surface of a photoreceptor.

Claims (1)

[Claims] (1) In an electrophotographic apparatus having a charger that energizes a charging wire along the surface of a photoreceptor and charges the surface of the photoreceptor with static electricity through corona discharge, the center of the charging wire is connected to the surface of the photoreceptor. An electrophotographic apparatus characterized in that an installation interval is set wider than an installation interval at both ends of the apparatus.