JP2518716Y2 - Push button switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a push button switch having a conductive portion on the inner upper side of a hollow mesa-shaped (reversed bowl-shaped) elastic body.

"Prior Art" There are known examples of the push button switch described in JP-A-64-3930 and JP-A-63-18727, and as shown in FIG. 3, insulation made of an elastic material such as silicone rubber is used. A conductive portion 2 made of a conductive material on the upper inside of a flexible hollow mesa-shaped elastic body 1,
It has a shape integrally formed downward, and when the elastic body 1 is pushed down, the contact point 12 on the substrate 15 and the conductive portion 2 are brought into contact with each other.

[Problems to be Solved by the Invention] In the above-described known push button switch, the conductive portion 2 is integrally projecting inside the hollow mesa-shaped elastic body 1. As shown in the figure, since the injection gate 11 must be set on the lower surface of the conductive portion 2, the lower surface of the conductive portion 2 after molding, that is, the flat contact surface 5 of the conductive portion 2 is formed.
A residual protrusion 4 due to the injection gate 11 is generated at the end, and this residual protrusion 4 becomes a harmful substance, which easily causes a contact failure between the conductive portion 2 and the contact 12. It is necessary to remove the residual protrusion 4 to prevent it. Therefore, there is a problem that the number of unnecessary removal steps increases and the cost increases.

The present invention provides a push button switch that solves the above-mentioned drawbacks of the conventional means.

"Means for Solving the Problems" The push button switch of the present invention which solves the above technical problems is "a hollow mesa-shaped elastic body integrally provided with a conductive portion having a flat contact surface facing downward. In the push button switch, a concave portion is formed in the central portion of the lower surface of the conductive portion, the outside of the concave portion is formed into a flat contact surface, and the concave portion is
It has at least "a shape having a depth sufficient to accommodate the entire length of the residual projection based on the injection gate of the injection molding by the molding die".

[Operation] In the push-button switch of the present invention having the above-described configuration, the concave portion is provided at the center of the lower surface of the conductive portion, and the outer lower surface of the concave portion is the flat contact surface.
The injection gate can be set in the recess. Therefore, even if a residual protrusion is generated due to the injection gate, the entire residual protrusion is accommodated in the concave portion, so that the contact action between the flat contact surface existing outside the concave portion and the mating contact is excellent. Reserved.

"Example" Hereinafter, a detailed description will be given based on examples. First, referring to FIG. 1 of an embodiment of the present invention, a conductive portion 2 is provided so that a flat contact surface 5 faces downward on an inner upper portion of a hollow mesa-shaped elastic body 1.
In the push button switch having, a circular concave portion 3 that is concentric with the conductive portion 2 is provided at the center of the lower surface of the conductive portion 2,
The outer portion of the concave portion 3 is formed on the flat contact surface 5 on the lower surface of the conductive portion 2. That is, the recessed portion 3 accommodates the residual protrusion 4 based on the injection gate that occurs when the push button switch is injection molded, and the depth D is carefully selected so that the residual protrusion 4 does not protrude from the flat contact surface 5. There is.

Next, a method of molding the push button switch of the embodiment shown in FIG. 1 will be described with reference to FIG. That is, this push button switch is mass-produced by injection molding with a molding die, and a fixed die 7 and a movable die 8 joined together in a part line 6 are used. First, an elastic body of the elastic body 1 excluding the conductive portion 2 is used. The movable die 8 having the cavity 9 is an elastic body injection gate of the fixed die 7.
The elastic body 1 is primarily molded by being joined to the portion 11A.

Then, after the elastic body 1 is cooled and solidified by the above-mentioned primary molding, the elastic body 1 of the primary molding is attached to the portion of the fixed die 7 having the conductive cavity 10 of the conductive portion 2 having the concave portion 3 and the conductive portion injection gate 11B. The movable die 8 mounted and molded is rotationally or slidably moved and joined as shown in FIG. 2 (B), the conductive portion 2 is secondarily molded by injection from the injection gate 11B, and after the conductive portion 2 is cooled and solidified. The fixed die 7 and the movable die 8 are separated and opened, and the push button switch having a desired shape is taken out.

In the figure, 13 is an injection runner groove, and 14 is an injection nozzle.

In the push button switch of the above-mentioned embodiment, since the residual protrusion 4 is completely housed in the recessed portion 3, the above-mentioned operation is achieved, and
The extra thick of the conductive portion 2 due to the provision of the concave portion 3 is removed,
In addition to saving the material, the work of removing the residual protrusion 4 becomes unnecessary.

The elastic body 1 of the push-button switch of the present invention is made of thermoplastic elastomer or thermosetting rubber having an injection molding die, and the conductive portion 2 is made to be capable of being bonded to the elastic body 1 by injection molding. , A thermoplastic elastomer to which conductivity is imparted by adding carbon powder or metal powder, or a thermosetting rubber having injection moldability.

[Advantages of the Invention] As described above, in the push-button switch of the present invention, the harmful residual protrusion due to the injection gate does not exist on the contact surface side of the conductive portion, so that a good switch function is stabilized and Since the work of removing the remaining protrusions is unnecessary, the molding process of the push button switch is simplified and the cost is reduced.
Furthermore, there is an effect of saving material by removing extraneous material in the conductive portion.

[Brief description of drawings]

FIG. 1: A push button switch according to an embodiment of the present invention, (A)
Is its front view, (B) is its bottom view, and FIG. 2 (A).
(B): FIG. 1 is a front view showing the molding method of the embodiment, FIG.
Figure: Front view of conventional push button switch, Figure 4: Front view of conventional push button switch molding method , 5: Flat contact surface, 6: Part line, 7: Fixed type, 8: Movable type, 9: Elastic body cavity, 10: Conductive section cavity, 1
1: injection gate, 12: contact

Claims (1)

(57) [Scope of utility model registration request] 1. A push button switch in which a conductive portion having a flat contact surface facing downward is integrally provided on an upper inner side of a hollow mesa-shaped elastic body, and a concave portion is formed in a central portion of a lower surface of the conductive portion. The outside of the recess is formed into a flat contact surface, and the recess has a shape having at least "a depth sufficient to accommodate the entire length of the remaining projection based on the injection gate of the injection molding by the mold". And push button switch.