JPH02991Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improved structure of a small switch for mounting on a printed wiring board using molded plastic for the switch operation part, and aims to eliminate problems caused by static electricity.

In conventional switches for the above applications, if the operating part is made of an insulating material such as plastic,
When the operating section itself is charged with static electricity, or when static electricity charged on the human body appears on the surface of the operating section through the operating fingers, this static electricity can cause the switch to open or close if there is no escape route from the operating section to the ground. There is a problem in that it affects the potential of the contacts and causes damage to the circuits of the switch and related equipment. In other words, although an insulating slider is interposed between the metal operating rod to which the operating section is attached and the switching contact section, the surface insulation of this slider is relatively low due to its structure. In the case of high-voltage static electricity, it is thought that it affects the opening/closing contact portion in a conductive manner or generally in an electrostatic induction manner.

In view of the above points, the present invention uses molded plastic for the operating section of this type of switch, but makes the entire or a necessary part of it from conductive plastic, in order to quickly dissipate the static electricity that appears on the operating section to the ground. In addition, a metal cover or mounting plate attached to the top surface of the switch body housing the opening/closing contact section is provided with a claw piece that is inserted into the hole in the printed wiring board, and this claw piece is connected to the ground on the surface of the wiring board. By contacting a conductor, static electricity in the operating section can easily escape from the operating rod to the ground through the conductive sleeve that is in constant contact with the operating rod and the cover or mounting plate that attaches it. It is.

Conventionally, the surface of plastic has been plated with the intention of beautifying the appearance of the switch operation part, but although the plating makes the surface conductive, it is intended to dissipate static electricity in a controlled manner. Not only is it fundamentally different from the above-mentioned present invention because it does not have a structure in which a grounding path is formed, but plating processing also has the drawback of being relatively high in cost, and the exterior color is only the single color of the metal coating. However, it also has disadvantages such as being easy to peel off.

To explain one embodiment of the present invention with reference to the drawings,
In Fig. 1, 1 is an insulating switch body, and three fixed contact pieces/terminals 11, 1 are attached to the bottom wall of the switch body.
2 and 13 are penetrated and fixed, and a movable contact piece 10 is supported on the center contact piece 12 so as to be tiltable left and right in a seesaw manner. These fixed contact pieces 11 to 13 and the movable contact piece 10 constitute an opening/closing contact portion. A metal cover 2 is attached to the open upper surface of the main body 1, and a metal mounting plate 3 is further attached thereon. As shown in FIG. 2, the cover 2 consists of a top plate 2a and front and rear hanging plates 2b.
The cover 2 is fixed to the main body 1 by bending the two front and rear claw pieces 2d of the lower end of the hanging plate 2b to the corresponding downward step surface of the main body 1. Mounting plate 3 is top plate 3
a and left and right hanging plates 3b, each hanging plate 3b
Two downwardly protruding claw pieces 3c are formed at the lower ends of each. The claw piece 3c is used for mounting the switch and also for grounding, which is the main purpose of the present invention.

A circular hole is formed in the center of each upper surface plate of the cover 2 and the mounting plate 3, and the lower end of the metal sleeve 4 is caulked and fixed around the hole. Due to this fixation, the mounting plate 3 is also fixed to the main body 1 via the cover 2. A metal moving rod 5 is inserted into the sleeve 4, and an insulating slider 7 is inserted into a recess deeply recessed upward from the lower end surface of the sleeve 4 with a compression spring 8 interposed therebetween. The lower end of the slider 7 is placed on the movable contact piece 10 so as to be movable left and right. The spherical part formed in the center of the actuating rod 5 hits the periphery of the circular hole at the upper end of the sleeve 4, and the spring 8
The sleeve 4 and the actuating rod 5 are kept in contact with each other at all times. Further, the actuating rod 5 tilts left and right around the spherical portion.

An operator 6 is fitted to the upper end of the actuating rod 5. This control is made of molded plastic, especially conductive plastic.The material is ordinary insulating plastic mixed with fine metal powder or conductive carbon black, and its resistivity is
10 ⁸ to 10 ³ Ωcm or less. In order to ensure the support of the operator 6, a bearing piece 3d is provided that is bent upward at a right angle from the center of each front and rear edge of the top plate 3a of the mounting plate, and the operator 6 is inserted into the hole in the upper part of the bearing piece 3d.
A short shaft rod protruding outward from the front and rear plates of is inserted and supported.

In Figure 2, this switch is connected to a printed wiring board 20.
To attach the three terminals 11 to 13 and the two left and right claw pieces 3c to the corresponding holes 20 of the plate 20,
a, connect them to individual printed wiring provided on the back side of the board 20, and then fix by soldering. As a result, the present switch is firmly attached to the plate 20, and at the same time, the mounting plate 3 is grounded via the wiring on the corresponding back surface of the claw piece 3c. Therefore, when a person's charged hand touches the operator 6 to operate the switch, the static electricity is transferred to the metal actuating rod 5 in contact with the operator 6 → the metal sleeve 4 → the claw piece 3 of the mounting plate 3
It escapes from the grounded wiring on the back surface of the board 20 to the ground through the cable 20c, thereby avoiding the adverse effects of static electricity.

The modified operating element 6' shown in FIG. 3 has an insulating plastic part 6'a as a main body, and a conductive plastic part 6'b is formed thereon by molding. The operator 6' has the same overall shape as the operator 6 described above, but it has a continuous part 6'b, which mainly includes the upper surface that is touched by the human hand and the inner surface center that is in contact with the actuating rod 5. After the insulating plastic part 6'a is molded, only the insulating plastic part 6'a is formed by further molding. This embodiment is also the same as the previous embodiment in that static electricity applied to the operator is reliably discharged to the ground.

Another embodiment of the present invention shown in FIG. 4 is a switch which uses a lever-like operator 16 instead of the waveform operator 6 described above, and this operator is also made entirely of conductive plastic. Other parts are first
It is the same as shown. The only difference is that the operator 6 pushes the left and right halves of the upper surface downward, whereas the operator 16 pushes the upper protrusion left and right. Still another embodiment shown in FIG. 5 is one in which the present invention is applied to a push button switch.
is something that slides up and down. An operating element 16' is fitted into the upper end of the actuating rod 5', and this operating element is also entirely made of conductive plastic. The other structures are generally the same as those shown in the first figure. In addition to the above, the present invention can be similarly applied to other devices such as rotary switches.

FIG. 6 shows an embodiment in which the mounting plate 3 is omitted and the printed wiring board 20 is arranged vertically rather than horizontally as in the previous example. In the same figure, the cover 2' is the lower end claw piece 2 of the front and rear hanging plates 2b.
It is the same as the previous example in that it is fixed to the switch body 1 by d, but two claw pieces 2c are cut out from the front edge of the top plate and protrude forward. That is, the printed wiring board is arranged vertically in front of this switch, and each claw piece 2c is inserted into its two holes. 3
The fixed contact pieces/terminals 11', 12', and 13' are formed so as to penetrate downward through the bottom wall of the main body 1 and are bent at right angles to the rear and front. is inserted into each hole and connected to each wiring on the back side.
The wiring on the back side of the wiring board to which the claw piece 2c is connected is grounded. Furthermore, in this embodiment, an operator 1 of another shape different from any of the above-mentioned examples is provided at the upper end of the actuating rod 5.
6" is fitted. This operator is also entirely made of conductive plastic, or a necessary part as shown in FIG. 3 is made of conductive plastic. The other structure is generally the same as in FIG. The switch in this example is also a lever switch similar to that shown in FIG.

According to the present invention, all or a necessary part of the switch operation part is made of conductive plastic, and the claw piece for mounting on the printed wiring board and the grounding claw piece are also used. Static electricity can be reliably dissipated from the actuating rod to the sleeve and then to the mounting plate with a simple structure that does not require special parts, thereby eliminating the damage caused by static electricity to related equipment. In addition, compared to plating, it does not have the disadvantage of being easily peeled off, is less expensive, and has the advantage of being able to be colored in several colors as desired.

[Brief explanation of drawings]

Figure 1 is a cross-sectional elevational view of the switch according to the present invention.
Figure 2 is a perspective view showing the state immediately before installation, Figure 3
The figure is a cross-sectional elevational view showing a modification of the main part, FIGS. 4 and 5 are elevational views showing parts of each of two other embodiments,
FIG. 6 is a perspective view showing still another embodiment. 1... Switch body, 2... Cover, 3... Mounting plate, 4... Sleeve, 5... Operating rod, 6, 6',
16...Operator, 7...Insulating slider, 10-1
3...Opening/closing contact part, 20...Printed wiring board, 6'a
...Insulating plastic part, 6'b...Conductive plastic part, 2c, 3c...Claw pieces.

Claims (1)

[Scope of utility model registration request] A metal cover or a metal mounting plate is attached to the open upper surface of the insulating switch body, and the lower end of the metal sleeve is caulked and fixed to the center hole of the cover or mounting plate, and the switch is inserted into the sleeve. In a small switch for mounting on a printed wiring board, a metal actuating rod that opens and closes the opening/closing contact part in the main body is inserted through an insulating piece, and a molded plastic operator is covered on the actuating rod. , all or a continuous part of the operator, including the surface area that is touched by the hand and the area that comes into contact with the operating rod, is made of conductive plastic, and the operator is inserted into the hole of the printed wiring board in the cover or mounting plate. A small switch with a sleeve for printed wiring boards, which is equipped with a claw piece for mounting and grounding the switch.