JPH0552942B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a corona discharge device disposed near a photoreceptor inside the main body of a copying machine and used as a charging device for charging the photoreceptor. This invention relates to an improvement of a corona discharge device that does not cause uneven discharge.

[Prior Art] Conventionally, as this type of corona discharge device, the fourth
As shown in the figure, there is a shield a whose longitudinal section is approximately U-shaped and which is open on the photoreceptor side, a corotron wire b that is stretched within the shield a and generates corona ions, and a corotron wire b that is installed at both ends of the shield a. A device is known which is composed of a corotron wire b and a fitting c for attaching the end of the corotron wire b.

As shown in FIGS. 5 and 6, the conventional fixture c has a box portion d formed of an insulating material such as unsaturated polyester resin, polycarbonate resin, or ABS resin into a box shape, and a bottom surface of the box portion d. It consists of a protruding engaging part f that engages an attaching part e attached to the end of the corotron wire b, and a lid part g that covers the box part d.

In the conventional corona discharge device, when dew condenses on the inner surface of the fixture c, current leakage occurs from the corotron wire b to the shield a side through the moisture attached to the inner surface, that is, creepage leakage (current leakage).
There were cases where this occurred.

For this reason, in the past, a plurality of plate-shaped protrusions h were provided on the bottom surface of the fixture c on the side of the shield a to increase the creepage distance from the corotron wire b to the shield a, thereby reducing the creepage leakage. A configuration has been adopted to prevent this from occurring.

That is, by providing the protrusion h, the creepage distance (α+β+2γ) from the contact point i of the corotron wire b with the protrusion h to the shield a can be reduced.
This is because the voltage per unit length of the current flowing along the creepage surface becomes smaller when creepage leakage occurs, making it easier for the discharge to be cut off midway through. It was hot.

[Problems to be Solved by the Invention] However, in the conventional corona discharge device, forming the convex portion h on the fixture d increases the creepage distance, but on the other hand, the corotron wire b
Since the spatial distance between the wire b and the protrusion h becomes shorter, when the inner surface of the fixture d condenses and becomes conductive, an arc discharge (air spark discharge) occurs between the wire b and the protrusion h instead of the creepage leak described above. In addition, as shown in Fig. 5, creepage leakage is likely to occur through the wall j of the convex part h and the side wall k of the box part d, and if the distance between the convex parts h and h is narrow. , water droplets tend to accumulate in the concave portion l formed by these convex portions h, h and the bottom surface of the box portion d, resulting in disadvantages such as a shortening of the creepage distance.

As a result, creepage leakage and arc discharge tend to occur more frequently, the discharge of the corona discharge device temporarily or continuously stops, and the photoreceptor becomes insufficiently charged, forming a toner image on the copy paper. Not done. There are disadvantages such as so-called white spot development occurs, the fixture d melts due to heating such as arc discharge and becomes unusable, and in extreme cases it burns and causes a fire.

[Means and effects for solving the problems] The present invention was made by focusing on the above problems, and its object was thought to be to increase the creepage distance within the above-mentioned fixture. Provided is a corona discharge device in which creeping leakage, arc discharge, etc. are less likely to occur by forming no convex portions and forming the space distance between the corotron wire and the inner surface of the fixture to be approximately equal within the fixture. It's about doing.

That is, the present invention provides a shield that is disposed near a photoreceptor inside the main body of a copying machine and is open on the photoreceptor side, a corotron wire that is stretched within this shield, and a corotron wire that is provided at both ends of the shield. ,
A corona discharge device comprising a fitting made of an insulating material for attaching the end of a corotron wire, the fitting being fitted into a shield with an open side surface on the side where the corotron wire is stretched. A box-shaped sheathing section is provided, and a mounting surface for attaching the end of the corotron wire is installed at the position where the shortest spatial distance from the corotron wire to each inner surface of the sheathing section is equal, which is set upright on the inner bottom surface of this sheathing section. By constructing a rectangular parallelepiped-shaped mounting part, the shortest spatial distance from the corotron wire to each inner surface of the covering part is equalized in the above-mentioned mounting fixture, thereby preventing creepage leakage and arc discharge, and preventing discharge. This is to prevent unevenness.

[Example] Hereinafter, examples of the present invention will be described in detail with reference to the drawings.The corona discharge device of the present invention is similar to the conventional device, as shown in FIG. A corotron wire 2 that is stretched within the shield 1 to generate corona ions, and a pair of attachments provided at both ends of the shield 1 for attaching the ends of the wire 2. It is composed of tool 3.

The fixture 3 is made of flame-retardant polypropylene, which is an insulating material that repels water droplets and is hard to stain.As shown in FIGS. 2 and 3, the fixture 3 includes a rectangular bottom plate 4, A rectangular parallelepiped-shaped wire attachment part 5 erected at approximately the center of the
and a cover member 6 that surrounds the wire attachment portion 5 and has a substantially L-shaped vertical section with open sides of the shield 1 and the bottom plate 4, and is fitted to both ends of the shield 1. The lower surface side of the bottom plate 4 is bonded and fixed to the surface of the shield 1.

Further, as shown in FIGS. 2 and 3, the wire attachment portion 5 is located at a position where the shortest spatial distance from the corotron wire 2 to each inner surface of the covering portion consisting of the bottom plate 4 and the lid member 6 is equal. It has a mounting surface M on which the wire end is mounted. The mounting surface M is provided with a threaded portion 8 around which the end of the corotron wire 2 is wound and fixed via a washer 7, and a protrusion 9 with which the wire 2 is brought into contact and positioned. The corona discharge device of the present invention is constructed by stretching the corotron wire 2 between the fixtures 3.

The dimensions inside the fixture 3 are as shown in FIGS. 2 and 3, from the corotron wire 2 to the bottom plate 4.
and the shortest spatial distance to each inner wall of the lid part 6 y ₁ , y ₂ ,
Both y ₃ and y ₄ are approximately 9 mm, and the shortest creepage distance from the wire attachment part 5 to the shield 1 (z1 +
z2) is approximately 20 mm, and the distance _z3 from the mounting portion 5 to the side wall of the lid portion 6 is approximately 7 mm.

In the corona discharge device of the present invention configured in this manner, the shortest spatial distance between the corotron wire 2 and the inner wall of the fixture 3 surrounding it is approximately the same, so even if the inner wall is condensed, The electric lines of force from the corotron wire 2 to the inner wall surface are uniformly dispersed, which has the effect of preventing the occurrence of arc discharge.

In addition, in the above-mentioned fixture 3, there is no convex part that increases the creepage distance, and the corotron wire 2 and the inner wall of the above-mentioned lid part 6 are not in contact with each other. This has the effect that creepage leakage toward the upper wall and side walls of the lid portion 6 is less likely to occur.

Furthermore, since the above-mentioned fixture 3 has a smaller inner surface area than conventional fixtures, it has the advantage that dew condensation is less likely to occur and creeping leakage and arc discharge are less likely to occur.

In this attachment 5, the shortest creepage distance from the wire attachment part 5 to the shield 1 (Z ₁ +
Z ₂ ) is approximately 20 mm, which is shorter than conventional fittings, but the above-mentioned creepage leakage is less likely to occur compared to conventional corona discharge devices.

[Effects of the Invention] As described above, in the present invention, a fixture for attaching a corotron wire is composed of the above-mentioned sheathing part and a mounting part, and in the fixture, from the corotron wire to each inner surface of the sheathing part. Since the shortest spatial distances are made equal, arc discharge is less likely to occur and creepage leakage is also less likely to occur compared to conventional corona discharge devices.

Therefore, since the discharge does not stop temporarily or continuously, uneven discharge is less likely to occur, and the fixture does not melt due to heating.

[Brief explanation of the drawing]

1 to 3 show embodiments of the present invention, and FIG. 1 is a perspective view of the corona discharge device of the present invention;
FIGS. 2 and 3 show a front view and a side view of this fixture, and FIGS. 4 to 6 show a conventional corona discharge device, with FIG. 4 being a perspective view of the device, and FIG. 6 shows a perspective view of the fixture, and FIG. 6 shows a sectional view taken along the - plane of FIG. 4. Description of symbols, 1...Shield, 2...Corotron wire, 3...Mounting tool, 4...Bottom plate, 5...
Wire attachment part, 6... Lid part, 7... Washer, 8... Screw part, 9... Protrusion part.

Claims (1)

[Claims] 1. A shield disposed near the photoconductor inside the main body of the copying machine and open on the photoconductor side, a corotron wire stretched within this shield, and a corotron wire provided at both ends of the shield. a fitting made of an insulating material for attaching the end of the corona discharge device, the fitting being fitted within the shield;
A box-shaped sheathing part with an open side surface on the side where the corotron wire is stretched, and a box-shaped sheathing part erected on the inner bottom surface of this sheathing part, at a position where the shortest spatial distance from the corotron wire to each inner surface of the sheathing part is equal. 1. A corona discharge device comprising: a rectangular parallelepiped-shaped mounting portion having a mounting surface for mounting an end portion of a corotron wire.