JPH0765669A - Push button switch - Google Patents

Abstract

PURPOSE:To simplify the structure of a push button switch and heighten the reliability of the switch at a low cost. CONSTITUTION:An insulator 6 higher than fixed electrodes is set on a substrate 3 between a pair of the fixed electrodes 5A, 5B. A protective sheet 2 is positioned above the substrate 3 and a movable electrode 7 is set in the inner face of the protective sheet 2 in the way the electrode extends over the pair of fixed electrodes. A circular expanded part 8 larger than the external shape of the movable electrode 7 is formed in the outer face of the membrane sheet 1. A circular projected part 9 to push the periphery of the movable electrode 7 is formed in the inner face of the circular expanded part 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a push-button switch in which a movable electrode is brought into contact with a pair of fixed electrodes provided at a distance to conduct electricity.

[0002]

2. Description of the Related Art A conductive resin film piece (movable electrode) is arranged on fixed electrodes arranged at intervals, and the resin film piece is deformed by a push button (key top portion) separately provided to move the movable electrode. Japanese Patent Publication No. 53-26308 (59H51) discloses a push-button switch that performs switch operation by contact between a fixed electrode and a fixed electrode.

[0003]

However, in the conventional push button switch, a push button (key top portion) must be additionally provided, and the resin film piece (movable electrode) is formed into a spherical projection shape and a spherical projection shape. Since a circular deformation node is formed on the resin film piece, the structure is complicated.

Further, since the resin film piece is brought into contact with the fixed electrode by being deformed by the deformation node of the resin film piece, the resin film piece is fixed when the resin film piece has poor elasticity due to secular change or the like. There may be a case where the electrode cannot be restored while being in contact with it. Therefore, the operating accuracy at the time of operating the switch is lowered and the reliability is lacking.

In view of the above points, the present invention simplifies the structure of the push button switch, improves the operation accuracy of the switch, and improves reliability.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a pair of fixed electrodes arranged on a substrate at a distance, a protective sheet positioned above the substrate, and attached to the inner surface of the protective sheet. And a movable electrode having a distance from the pair of fixed electrodes and arranged across the pair of fixed electrodes, and a membrane sheet provided on the protective sheet. When a switch is operated by bringing the movable electrode into contact with the fixed electrode by applying pressure from above, an insulator higher than the height of the fixed electrode is provided on the substrate between the pair of fixed electrodes, and the outer surface of the membrane sheet is provided. And an annular bulge larger than the outer shape of the movable electrode is formed on the inner surface of the movable electrode, and an annular protrusion for pressing the peripheral edge of the movable electrode is formed on the inner surface of the annular bulge.

[0007]

When the switch is operated and the annular bulging portion is pressed from above the membrane sheet, the annular protrusion presses the peripheral edge of the movable electrode and contacts the fixed electrode. Since the central portion of the movable electrode is in contact with the insulator, only the peripheral edge of the movable electrode is deformed downward, and the restoring force is accumulated in the movable electrode at this time.

When the pressing force on the membrane sheet is released, the movable electrode is restored by the accumulated restoring force and is separated from the fixed electrode. Further, even if there is a secular change, the separation between the fixed electrode and the movable electrode is maintained due to the presence of the insulator higher than the height of the fixed electrode.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a push button switch of the present invention provided in an operation section for operating a device. Reference numeral 1 is a membrane sheet covering the surface of the operating portion, 2 is a protective sheet formed by a vinyl sheet or the like arranged on the lower surface of the membrane sheet 1, and 3 is a concave portion 4 formed on the upper portion. Resin control board, 5A
And 5B are a pair of fixed electrodes which are fixed to the concave portion 4 of the control substrate 3 to form a switch circuit, and 6 is an insulator which is positioned between the fixed electrodes 5A and 5B and fixed to the concave portion 4. The height is higher than the height of the fixed electrodes 5A and 5B.

Reference numeral 7 denotes a movable electrode formed of an elastically deformable conductive resin film piece attached to the inner surface of the protective sheet 2, which has a small clearance from the pair of fixed electrodes 5A and 5B and which is a pair. It is arranged across the fixed electrode.

Reference numeral 8 denotes an annular bulging portion formed on the membrane sheet 1 so as to bulge integrally with the sheet toward the outer surface, and is provided larger than the outer shape of the movable electrode 7 to provide a pressing area when the switch is operated. It also serves to display (switch operation display section).

Reference numeral 9 denotes an inwardly projecting annular projection on the inner surface of the annular bulging portion 8 for pressing the peripheral edge of the movable electrode 7.

Reference numeral 10 is a control box which is electrically connected to the push button switch of the present invention and which controls the electric load of the equipment, which is not shown but is integrated with the control board 3 by screws or the like. is there.

The control box 10 is a case formed of a non-conductive material such as polyethylene or polypropylene in a box shape.
11, a plate-like spacer 12 made of poly-ethylene, polypropylene or the like, which is housed in the case 11 and partially formed integrally with a thick portion 12A, and a circuit including a switch circuit for the fixed electrodes 5A and 5B. A printed circuit board 13 on which printed wiring is provided, and an electronic component 15 such as a diode, a transistor, a capacitor, an LED, etc., which is mounted on the printed circuit board 13 and soldered 14;
The case (11) is filled with a filler (16) made of urethane resin for insulation and waterproofing. The filler 16 covers the entire area on the front surface side where the electric component 15 is attached to the printed circuit board 13, and the thick portion 12 on the rear surface side of the printed circuit board 13.
It covers 14 parts of soldering except A.

Since the thick wall portion 12A is partially formed in the spacer 12 (the portion which does not need to be insulated and waterproofed), the amount of expensive insulating resin (urethane type) is reduced to reduce the cost. The printed circuit board 13 and the electrical components 15 can be insulated and waterproofed.

Next, the operation of the push button switch of the present invention will be described. When the central portion of the annular bulging portion 8 of the membrane sheet 1 is pressed, the peripheral edge of the movable electrode 7 is protected by the annular projection 9.
The pair of fixed electrodes 5A and 5B are pressed and come into contact with each other. When the pressing force is released, the movable electrode 7 is restored.

Further, since the insulator 6 which is higher than the height of the fixed electrodes 5A and 5B is disposed between the pair of fixed electrodes 5A and 5B, the protective sheet 2 extends with the lapse of time and the movable electrode 7 moves downward. Even if it hangs down, the insulator 6 supports the lowering of the movable electrode 7 and blocks the conduction between the fixed electrodes 5A and 5B.

[0018]

According to the present invention, since the annular bulge portion is formed in the membrane sheet to serve as the switch operation area, the entire structure is simplified without separately providing a push button or a switch operation display portion. it can.

Further, since the annular bulging portion and the annular protrusion are formed in the membrane sheet, the annular bulging portion and the annular protrusion increase the strength of the membrane sheet, and therefore the membrane sheet does not loosen. .

Further, since the insulator higher than the height of this fixed electrode is provided between the pair of fixed electrodes, the contact between the movable electrode and the fixed electrode is blocked by this insulator, and the reliability of the switch operation is improved.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part of a push button switch of the present invention.

FIG. 2 is a switch operation state diagram of the same.

FIG. 3 is a sectional view of a main part of a control box used for the push button switch of the present invention.

FIG. 4 is a perspective view of a spacer used for the control box.

[Explanation of symbols]

 1 Membrane Sheet 2 Protective Sheet 3 Control Board 5A, 5B Fixed Electrode 6 Insulator 7 Movable Electrode 8 Annular Swelling 9 Annular Protrusion

Claims (1)

[Claims] 1. A pair of fixed electrodes arranged on a substrate at a distance, a protective sheet positioned above the substrate, and a pair of fixed electrodes attached to the inner surface of the protective sheet. It is provided with a movable electrode having a space and arranged over a pair of fixed electrodes, and a membrane sheet provided on the protective sheet, and the membrane sheet is movable by applying pressure from above. In a switch operation in which an electrode is brought into contact with a fixed electrode, an insulator having a height higher than that of the fixed electrode is provided on a substrate between a pair of fixed electrodes, and the outer surface of the membrane sheet is larger than the outer shape of the movable electrode. A pushbutton switch characterized in that a large annular bulging portion is formed, and an annular projection for pressing the peripheral edge of the movable electrode is formed on the inner surface of the annular bulging portion.