JPS61247738A - Plastic bearing - Google Patents

Abstract

PURPOSE:An expensive plastic bearing protected from a trouble due to static electricity, comprising a specified plastic material. CONSTITUTION:Accumulation of electrostatic charges on a shaft 3 is prevented by facilitating the discharge of electrostatic charges to a frame 1 by attaching thereto a bearing 2 which is made of a plastic material mixed with fine metallic pieces, carbon particles, or the like, or coated with a surface film such as an electroconductive film and has a decreased electric conductivity of 10<-8>OMEGA cm or below.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic bearing used in rotating parts of electronic equipment, OA equipment, etc.

[Conventional technology]

Recent advances in plastic materials have made significant progress in the wear resistance of plastic materials, and plastics, which can be mass-produced and are inexpensive, have replaced the metal bearings traditionally used as bearings for medium- and low-speed rotating parts. Increasingly, materials are being used.

In particular, plastic materials are extremely suitable for mass-produced electronic equipment such as office automation equipment, where price competition is fierce.Plastic materials are used in parts of the structure that do not require particularly high mechanical strength. ing.

[Problem that the invention seeks to solve]

However, the good electrical insulation performance, which was an advantage of plastic materials, actually becomes a disadvantage when plastic materials are used as bearings. Even if electric charges accumulate on the metal part of the shaft due to friction, they are difficult to discharge. Static electricity builds up, which causes problems such as fine dust adsorption, paper adsorption, malfunction of electronic circuits when electrostatic discharge exceeds dielectric breakdown voltage, and even generation of radio noise. It became so.

The present invention was made in order to solve the above-mentioned problems, and the object is to obtain a plastic bearing that does not cause various problems due to static electricity accumulation even when used as a bearing material. It is.

[Failure to solve the problem]

To achieve the above-mentioned purpose, the present invention provides a plastic bearing using conductive properties imparted to plastic.

[Effect]

Since the plastic bearing according to the present invention has conductive properties, it can constantly discharge static electricity, does not accumulate electric charge, and therefore does not cause problems due to static electricity charging.

〔Example〕

FIG. 1(A) is a front view showing a cross section of a plastic bearing according to an embodiment of the present invention, and FIG. 1(B) is a side view thereof.

In the figure, (1) has 7 frames, the frame (1) is provided with a plastic bearing (2), and the shaft (3)
is stably protected by a plastic bearing (2) and passes through the frame (1). Plastic bearing (2)
is made of a plastic material that has been given electrically conductive properties.

Giving conductive properties to plastics in this way is also done, for example, in order to obtain a radio wave shielding effect on plastic covers of electronic devices, etc., and there are the following methods for this purpose.

(1) Mixing metal pieces, carbon powder, etc. into plastic materials.

(2) A coating film of conductive paint is formed on the surface of the plastic molded product.

(3) Depositing or sputtering a metal film on the surface of the plastic molded product.

By applying these methods to plastic bearings, the electrostatic charge that tends to accumulate on the shaft (3) in Figure 1 will be reduced.
Electrical discharge can be easily carried out on the frame via the plastic bearing (2) which is endowed with electrically conductive properties.

The conductivity required for electrostatic discharge is 10sΩ-c
A slight conductivity on the order of rn (ohm centimeter) or less is sufficient, and any of the above methods (1) to (3) can easily provide a means for discharging.

FIG. 2 is an explanatory diagram showing the discharge path of static electricity as an electrical equivalent circuit, in which (1) corresponds to the frame, (2) corresponds to the plastic bearing, and (3) corresponds to the shaft.

In the above embodiment, the frame (1) is assumed to be made of a conductive material, for example, metal. However, if the frame (1) is made of insulating plastic, the plastic bearing (2) may be used. By using it as if it were a slip ring in an alternating current machine and providing grounding from the plastic bearing (2) with an electric wire or the like, the same effect as providing a freely slidable contact piece can be obtained.

〔Effect of the invention〕

According to the present invention, by configuring the plastic bearing to have conductive properties, it is possible to prevent damage caused by static electricity with an inexpensive bearing.

[Brief explanation of drawings]

FIG. 1 (N is a front view showing a cross section of a plastic bearing according to an embodiment of the present invention, (B) is a side view thereof, and FIG. 2 is an explanatory diagram of an electrical equivalent circuit corresponding to FIG. 1. 1: 7 frames, 2: Nigelastic bearings, 3: Shaft. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A plastic bearing characterized by using a plastic material having conductive properties. (2) A plastic bearing according to claim 1, characterized in that it uses a plastic material mixed with a substance exhibiting electrically conductive properties, such as metal flakes and carbon particles. (3) The plastic bearing according to claim 1, characterized in that a plastic material having a surface coating film exhibiting electrically conductive properties, such as an electrically conductive coating film, is used.