JPS6243018A - Contact rubber for push button switch - 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 a contact rubber for a push button switch that is provided in many word processors, computer input keyboards, and the like.

[Prior art and its problems]

The contact rubber of a conventional push button switch was constructed as shown in FIG. That is, a conductive rubber in which carbon black or the like is dispersed is integrally adhered to the surface of an insulating rubber 4 made of silicone rubber or the like, and a current-carrying contact surface 2 is formed on the surface of the conductive rubber. All of the contact rubbers are attached to a support block 5, and in response to the vertical movement of the support block 5, the current-carrying contact surface 2 connects and disconnects the electrical contacts s and s' of the board 9. . The conductive contacts s and s' have a plane pattern of, for example, the sixth
It was formed into a comb shape as shown in the figure. That is, in FIG. 6, they are arranged in a U-shape with a slight distance from each other, as indicated by s and S/ within the chain line frame, and are connected to lead conductors J and H, respectively. A large number of such electrodes are arranged spaced apart from each other.

However, as long as a contact rubber as shown in FIG. 7 is used, at least the current-carrying contact surface 2 of the contact rubber
Since a portion corresponding to the total surface area of the electrode S is short-circuited on the substrate 90 substrate.

No lead conductors other than those connected to S' can be laid around S'. That is, other lead conductors cannot be laid between the electrodes s and s' or in the vicinity thereof, and the lead conductors are laid in a detour to avoid the vicinity thereof. Therefore, jumper wire portions X are required at various locations as shown in FIG. Then, this jumper wire portion X and the lead conductor 1. J.

Since it is necessary to insulate each other from K, many man-hours are required to manufacture the printed circuit board.

At the same time, the insulation at the jumper wire portion X deteriorates, reducing the reliability of the board. Furthermore, instead of using such a jumper wire section X, the following method has also been used. That is, conductors printed on hard insulating films were connected to each other through an insulating coating having holes formed at appropriate positions. However, in such a printed circuit board, it is necessary to form a larger number of printed patterns in a wider area, and the cost of the board increases accordingly. aims to provide a contact rubber that allows conductors for other leads to be laid between a pair of slightly spaced electrodes on a printed circuit board, thereby simplifying the printed pattern and replacing the traditional jumper wire section. This is to eliminate as much as possible to improve insulation and provide a printed circuit board at low cost. Its structure is as follows.

That is, the pushbutton switch has a conductive rubber which is attached to the lower surface of the pushbutton switch so as to be movable up and down, and which short-circuits between the slightly spaced electric handles so as to be freely accessible and detachable. Here, the feature of the present invention is that the cross section is made of conductive rubber formed into a substantially gate-like or bridge-like shape, and each leg end of the gate shape is exposed, and at least a pair of current-carrying contact surfaces are formed thereon. Configure 2.3. The area between both current-carrying contact surfaces 2.3 is covered with insulating rubber.

[Embodiments of the invention]

Next, each embodiment of the present invention will be described based on the drawings.

FIG. 1 is a cross-sectional view of the contact rubber of the present invention,
FIG. 2 is a view taken along the line nn in FIG. 1. FIG. 3 is an enlarged cross-sectional view of this contact rubber. As is clear from FIG. 3, this contact rubber has a conductive rubber 12 whose cross section is approximately gate-shaped. Then, the outer periphery of the conductive rubber 12O except for the leg ends is covered with an insulating base 1 made of insulating rubber. At the same time, the inner periphery of the conductive rubber 12 is covered with the insulating rubber 4.

A protrusion 10 is formed in the center of the insulating rubber 4. Here, the insulating base 1 and the insulating rubber 4 are both made of insulating silicone rubber with a hardness of H375 or higher, and the conductive rubber 12 is made of silicone rubber in which conductive fine particles such as carbon black are dispersed. A material having a resistivity of 4Ω1 and a hardness of H365 to H75 is used as an example. The tips of the current-carrying contact surfaces 2.3 are each made into slightly curved planes, and the tops of the protrusions 10 are slightly (0.1
tm). Further, such contact rubber is integrally formed by extrusion using an extrusion molding machine having two irradiation tubes. That is, the conductive rubber 12 is extruded from one injection tube, and the insulating rubber 4 covering the inner and outer peripheries of the rubber 12 is extruded from the other injection tube to form a thin strip. Then, by cutting it across into rings at intervals of about 3N, for example, a large number of contact rubbers can be manufactured.

[For production]

Next, how to use this contact rubber will be explained.

In this contact rubber, as shown in FIGS. 1 and 2, an insulating base 1 is attached to the lower surface of a support block 5 by adhesive or other means. Note that the upper surface of the insulating base 1 is the support block 5.
It does not necessarily have to be completely bonded to the bottom surface; for example, in the figure, only the upper surfaces of both left and right ends of the insulating base I are bonded to the bottom surface of the support block 5, and the middle portion is bonded to the bottom surface of the support block 5 so that a space is formed between it and the support block 5. It may be configured as follows. Next, a shaft 6 is integrally provided on this support block 5,
A key top 7 is fixed to the upper end of the shaft 6. or,
A guide frame 8 is provided on the outer periphery of the support block 5, and a protrusion or the like of the support block 5 (not shown) fitted into a guide groove (not shown) on the outer surface of the guide frame 8 is guided to move up and down. . Further, the outer surface of the guide frame 8 is removably fixed to a support frame of a keyboard (not shown). Further, a return rubber 1) having a bell-shaped protrusion is interposed between the upper surface of the support block 5 and the key top 7. In this return rubber 1), when the key top 7 is pushed downward, the bell portion is elastically deformed, and the elastic force causes the key to be closed.

This is to restore step 7. Further, a substrate 9 is provided opposite the lower surface of the contact rubber.

This substrate 9 is made of a film or plate-like material made of a hard synthetic resin material. Then, on its surface, electric jf4 a, a'
is provided by printing or etching, etc., facing the current-carrying contact surface 2.3, and lead conductors B-D are laid between them as shown in FIGS. 1 and 4. That is, in this embodiment, as is clear from FIG. 4, electrodes A and E are electrically connected to electrodes a and a' spaced apart from each other, respectively. Then, by pressing the support professional 7ri 5, a.
A' is short-circuited. However, as is clear from FIG. 1, the current-carrying contact surfaces 2 and 3 that short-circuit the two are formed in the shape of a bridge, and an insulating rubber 4 is provided in the middle thereof. Therefore, even if a and a' are short-circuited, the lead wires B-D installed between them are not short-circuited. As a result, only A and E are electrically connected. If another support block 5 is pressed to short-circuit between B and B', only B-E will be short-circuited. In addition, in FIGS. 1 and 3, the protrusion 1o formed at the center of the insulating rubber 4 concentrates the pressing force on the current-carrying contact surfaces 2 and 3 as much as possible, so that most of the insulating rubber 4 is placed on the substrate 9. This prevents pressure from being applied to the surface and ensures reliable contact between conductors.

Incidentally, if such a contact rubber is used, the print pattern shown in FIG. 6 can be easily simplified as shown in FIG. 5. That is, FIG. 5 is an example of a design change of the section ``■'' surrounded by a chain line frame in FIG. 6, and when this contact rubber is used, the design can be simplified as shown in the same figure. As a result, the jumper wire portion X in FIG. 6 becomes almost unnecessary.

For example, as shown in Fig. 5, between t, 17, q, q'
Between each lead conductor J, 1. This is based on the fact that it can be installed. And this, as shown in Figure 3,
This is possible because the conductive rubber 12 has a bridge shape and the insulating rubber 4 is provided between the legs.

〔Effect of the invention〕

The contact rubber of the present invention has the above structure and has the following effects.

(1) This contact rubber has a conductive rubber whose cross section is formed into a gate shape or a bridge shape, and the zero leg ends of each of the gate shapes are exposed to form at least a pair of current-carrying contact surfaces 2 and 3. . Since the area between the two current-carrying contact surfaces 2.3 is covered with insulating rubber, a pair of electrodes a and a' facing the contact rubber and in contact with the contact rubber can be freely approached and separated, as shown in FIGS. 1 and 4. As an example, lead conductors A to D can be laid on the substrate 9 as shown in FIG. This simplifies the pattern of the printed circuit board, reduces the number of conventional jumper wires and the like as much as possible, and makes it possible to manufacture a printed circuit board that is easy to design and inexpensive.

(2) Also, according to this contact rubber, the number of jumper wires, etc. that were conventionally used can be reduced as much as possible, so insulation defects that occur in the jumper wire (section X in Figure 6) can be avoided.
This makes it possible to create reliable printed circuit boards.

(3) Furthermore, since this contact rubber is made of conductive rubber formed into an almost gate-shaped or pre-fuji shape, and insulating rubber is covered between the legs, this contact rubber is manufactured by extrusion molding. However, since it can be manufactured by cutting it across to an appropriate length, the contact rubber itself can also be manufactured at low cost.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the contact rubber of the present invention, Fig. 2 is a view taken along the ■-■ arrow in Fig. 1, Fig. 3 is an enlarged sectional view of the contact rubber, and Fig. 4 is the bottom surface of the contact rubber. Fig. 5 shows an example of a pattern of a printed circuit board disposed facing the contact rubber of the present invention, and Fig. 5 shows an example of a holding pattern. An example of a design change, Figure 6 is an example of a printed circuit board pattern used for a conventional contact rubber.
FIG. 7 is a sectional view of a conventional contact rubber. 1... Insulating base 2.3... Current-carrying contact surface 4...
・Insulating rubber 5-Support block 6...Shaft 7...Key top 8...Guide frame
9... Substrate 10... Projection 1)... Rubber cylinder for return 12... Conductive rubber a''-s... Electrode A-K... Lead conductor X... Jumper wire Department Agent Patent Attorney Kubo 1) Takumi Figure 1

Claims (1)

[Claims] It is attached to the bottom of the push button switch so that it can move up and down.
In a contact rubber having a conductive rubber in which electrodes slightly spaced apart are short-circuited so as to be freely connected and separated, an insulating base (1
), the cross section is formed into a substantially gate shape or bridge shape, and each leg end of the gate shape is exposed to form at least a pair of current-carrying contact surfaces (2), (3). A contact rubber for a push button switch, characterized in that the current-carrying contact surfaces (2) and (3) are covered with insulating rubber.