JPH02117013A - Electrode wire - Google Patents

Abstract

PURPOSE:To make the manufacture easier and to make it possible to sustain a corona discharge stably for a long period by providing a platinum coverage layer further on the surface of a gold coverage layer. CONSTITUTION:A gold layer 2 is provided on the surface of a tungsten core wire 1, and furthermore, a platinum coverage layer 3 is provided on the surface of the gold coverage layer 2. By using tungsten for the core wire, an excellent mechanical strength is obtained, a sufficient tensile force can be given to an electrode wire when it is extended long on a device, and a swinging of wire and the like in the service can be prevented. And since the platinum coverage layer is formed over the gold lining layer, the gold does not contact to the ambiance directly, and the uneven discharge owing to the oxidization and the like in the service is not generated even though it is used for a long time. Consequently, an excellent anti-abrasive and anti-oxidizing properties can be obtained, a stable corona discharge is realized, and the manufacture is also easy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in electrode wires used in corona discharge devices and the like.

[Conventional technology and problems]

Corona discharge devices are used in copiers, dust collectors, etc., and the surface of the tungsten wire, which has excellent mechanical properties, is coated with a uniform oxide film to prevent oxidation of the tungsten wire. A formed surface oxidized tungsten wire or a gold-plated tungsten wire coated with gold is used.

However, in surface oxidized tungsten wires, it is difficult to obtain a sufficiently dense and defect-free oxide film to prevent oxygen diffusion, and the protection of the electrode wires has been insufficient. Further, when gold-plated tungsten wire is used for a long time, deposits may be observed, and the tungsten wire may be oxidized by ozone or the like due to plating defects.

This oxidation and deposits caused uneven discharge and uneven copying, especially in copying machines.

In addition, so-called platinum-clad tungsten wire, which is a tungsten wire covered with a platinum pipe and then drawn, is also used. This electrode wire is expected to provide stable corona discharge over a long period of time, but since the hardness and ductility of platinum and tungsten are significantly different, it is difficult to draw the wire, and losses due to wire breakage occur during the manufacturing process. However, the disadvantages are that the quality of the product varies widely and it is inevitably expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel electrode wire that solves the problems of the prior art, is easy to manufacture, and can provide stable corona discharge for a long period of time.

[Means and effects for solving the problem] The present inventor provides an electrode wire in which a gold coating layer is provided on the surface of a tungsten core wire, and a platinum coating layer is further provided on the surface of this gold coating layer. Thus, the above problems were solved and the above objectives were achieved.

Tungsten is used for the core wire because tungsten is a metal with a high melting point and has excellent mechanical strength, allowing sufficient tension to be applied to the electrode wire when it is stretched over a long length of equipment, and preventing the wire from wobbling during use. This is because it can be done.

In the electrode wire of the present invention in which a platinum coating layer is formed on a gold base layer, the gold does not come into direct contact with the atmosphere, so uneven discharge due to oxidation etc. does not occur even when used for a long time. Although the details of why there is a difference in operating life between gold and platinum are not clear, it is presumed that there is a difference in the reactivity of the two to ozone and the like.

The reason why the gold underlayer is coated under the platinum layer is to improve the oxidation resistance of the electrode wire. As described below, the coating layer is easily formed by plating, but it is usually difficult to obtain an oxidation-resistant film with sufficient strength and thickness by plating only platinum. The thickness of the platinum layer on the surface of the electrode wire of the present invention may be a thin film of one layer or less, and therefore, unlike platinum clad wires, difficult processing such as covering with platinum metal and drawing the wire is not required.

Formation of the covering layer is not particularly limited, but plating is preferred for ease of production. The plating may be electrolytic plating, electroless plating or non-electrochemical plating. After forming the coating layer, lightly processing the surface, such as drawing, to make it smooth is effective for improving discharge characteristics.

Hereinafter, the content of the present invention will be explained in more detail according to Examples.

〔Example〕

A tungsten wire with a wire diameter of 73 mm was gold plated using a commonly practiced method using a cyanide bath, and then platinum plating was applied over the entire base layer using a chloroplatinic acid bath. . The thickness of the gold plating layer at this time was 4.1/al, and the thickness of the platinum layer was 0.334. Next, in order to make the surface smooth, wire was drawn to a wire diameter of 70 tones. The thickness of the gold and platinum coating layers after drawing was 4.33n.

The electrode wire of the present invention was produced as described above.

FIG. 1 shows a cross-sectional view of the electrode wire of the present invention.

The obtained electrode wire of the present invention was attached to the apparatus shown in FIG. 2, and DC discharge was performed using the electrode wire as an anode. The applied voltage at this time was 7 kV. At predetermined intervals, the case covered with the electrode wire was removed, the surface of the electrode wire was observed, and the case was attached to a commercially available electrophotographic copying machine to check for uneven copying.

For comparison, similar tests were also conducted on a surface oxidized tungsten wire and a gold-plated tungsten wire with a plating thickness of approximately 4 mm.

As a result, ordinary gold-plated tungsten wire has a discharge of 50
After 0 hours or less, discoloration occurred on the surface and uneven copying occurred. Further, the surface oxidized tungsten wire similarly exhibited copy unevenness after 700 hours of discharge. On the other hand, the electrode wire of the present invention in which the entire base layer was plated with platinum showed no surface discoloration or uneven copying even after 1000 hours or more.

〔Effect of the invention〕

As described above, the electrode wire of the present invention has excellent corrosion resistance, particularly oxidation resistance, can perform stable corona discharge for a long period of time, is relatively easy to manufacture, and has industrial utility value of the present invention. is big.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the electrode wire of the present invention. Figure 2 shows
1 is a schematic diagram of a corona discharge device used in an example of the present invention. In the figure, 1: tungsten core wire, 2: gold coating layer 3: platinum coating layer, 4: high voltage generator 5: charge case, 6: electrode wire.

Claims (1)

[Claims] 1. An electrode wire having a gold coating layer on the surface of a tungsten core wire, characterized in that a platinum coating layer is further provided on the surface of the gold coating layer.