JP2001076585A - Membrane switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of contact points caused by the moisture flowing into a membrane switch used for the operation section of an electronic apparatus or the like with no additional component. SOLUTION: An upper membrane circuit sheet 1, a spacer sheet 2, and a lower membrane circuit sheet 3 are integrally laminated so that the contact points 1a, 3a provided on the upper and lower membrane circuit sheets 1, 3 are faced together in this membrane switch. Vent grooves 5 having the capacity larger than the air going into or out of the inside of the membrane switch when it is depressed or returned are formed between the vent hole 2b of the spacer sheet 2 and the contact points 1a, 3a. The moisture flowing in as the air goes in or out hardly reaches the contact points 1a, 3a, and the membrane switch with excellent water resistance is obtained with no additional component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane switch used for an operation section of an electronic device or the like.

[0002]

2. Description of the Related Art A conventional membrane switch generally used for an operation section of an electronic device or the like is configured as shown in FIGS.

That is, the upper membrane circuit sheet 1
And a spacer sheet 2 forming the ventilation groove 2a and the ventilation hole 2b, and a lower membrane circuit sheet 3 as main constituent members, which are laminated together and joined by an adhesive or the like to be integrated.

The upper membrane circuit sheet 1 and the lower membrane circuit sheet 3 have contact points 1 facing each other.
a, 3a are arranged, and the upper membrane circuit sheet 1
When the switch unit 1b is depressed via an operation key or the like, the contact points 1a and 3a facing each other are brought into contact to conduct electricity.

The air hole 2b formed in the spacer sheet 2 communicates with the outside air, and the pressure inside the membrane switch changes due to the pressing and returning operations of the membrane switch and the temperature change, and the volume inside the switch section 1b expands and expands. The air pressure is balanced so that the pressing / return operation is not affected by the contraction.

In the membrane switch having such a structure, when the operation section of the electronic device or the like is flooded, the air enters and exits from the vent hole 2b of the membrane switch through the ventilation groove 2a through the vent groove 2a, and the moisture enters and exits when returning. Flows in, and the contacts 1a and 3a deteriorate due to corrosion or the like.

Accordingly, as a waterproof measure for this type of membrane switch, as shown in FIGS.
By affixing a member such as a gas permeable waterproof seal member 4 to the air hole 2b communicating with the outside air (disclosed in Japanese Patent Application No. 10-154436), the flow of moisture into the inside of the membrane switch is cut off, and the contact 1a, 3a is prevented from deteriorating.

[0008]

By the way, the waterproofing of the membrane switch having the above-mentioned structure involves the problem of increasing the price and securing the space for the members because the members are added.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a membrane switch excellent in water resistance without adding members.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to provide a ventilation groove having a volume larger than that of air flowing into and out of the membrane switch when the membrane switch is pressed / returned, between the ventilation hole and the contact in the spacer sheet. It is configured to be formed.

According to the present invention, it is possible to realize a membrane switch having excellent water resistance without additional members.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, an upper membrane circuit sheet, a spacer sheet and a lower membrane circuit sheet are laminated and combined, and the contacts provided on the upper and lower membrane circuit sheets are opposed to each other. A membrane switch in which a ventilation groove having a volume equal to or greater than air flowing into and out of the membrane switch when the membrane switch is pressed / returned is formed between the ventilation hole and the contact in the spacer sheet, and the air between the ventilation hole and the contact is provided. By ensuring a certain volume or more of the ventilation groove for ingress and egress, it is difficult for the moisture flowing into the inside of the membrane switch to reach the contact point, making it easy to have excellent water resistance without additional members. Has an action.

According to a second aspect of the present invention, in the membrane switch according to the first aspect, the ventilation groove is formed in a rectangular wave shape. The ventilation groove secures a certain volume or more, and is provided inside the membrane switch. It has an effect that it is difficult for the inflowing water to reach the contact point.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is an exploded perspective view of a membrane switch according to a first embodiment of the present invention, and FIG. 2 is a front view of the membrane switch. In each drawing, the same components as those in the conventional example are denoted by the same reference numerals as in the conventional example.

As shown in FIGS. 1 and 2, this membrane switch comprises an upper membrane circuit sheet 1, a spacer sheet 2 forming ventilation grooves 5 and ventilation holes 2b.
The lower membrane circuit sheet 3 is used as a main constituent member, these are laminated with each other, and joined by an adhesive or the like to be laminated and united.

The upper membrane circuit sheet 1 and the lower membrane circuit sheet 3 have opposite contacts 1a,
3a is arranged. The ventilation holes 2b in the spacer sheet 2 are provided, for example, so as to penetrate from the front of the membrane switch.
And the contacts 1a and 3a.

The ventilation groove 5 formed by the spacer sheet has a small cross-sectional area so as not to affect the pressing / returning operation of the switch portion 1b so that water does not easily enter, and has a rectangular wave shape. The distance is extended to secure a volume larger than the air that enters and exits the inside of the membrane switch.

The membrane switch thus configured maintains the equilibrium between the air pressure inside the membrane switch and the outside air pressure even when the switch section 1b is pressed and returned, and also allows air to flow through the ventilation groove 5 from the ventilation hole 2b. Even if moisture flows into and out of the membrane switch as it enters and exits, the contact 1
a, 3a can be prevented from reaching water.

[0020]

As is apparent from the above description, the present invention secures a certain volume or more of the ventilation groove through which the air enters and exits between the ventilation hole and the contact point. This makes it difficult to reach the contact points, and can easily realize a membrane switch having excellent water resistance without additional members.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a membrane switch according to a first embodiment of the present invention.

FIG. 2 is a front view of the membrane switch.

FIG. 3 is an exploded perspective view of a conventional membrane switch.

FIG. 4 is a sectional view of the membrane switch.

FIG. 5 is an exploded perspective view of another conventional membrane switch.

FIG. 6 is a cross-sectional view of the membrane switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper membrane circuit sheet 1a Contact 1b Switch part 2 Spacer sheet 2b Vent hole 3 Lower membrane circuit sheet 3a Contact 5 Vent groove

Claims (2)

[Claims] 1. An upper membrane circuit sheet, a spacer sheet and a lower membrane circuit sheet are laminated and united.
A membrane switch in which contacts provided on a lower membrane circuit sheet are opposed to each other, wherein a ventilation groove having a volume equal to or greater than air flowing into and out of the membrane switch when the membrane switch is pressed / returned is formed between the ventilation hole and the contact in the spacer sheet. A membrane switch characterized by: 2. The membrane switch according to claim 1, wherein the ventilation groove is formed in a rectangular wave shape.