JP2001216866A - Switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dome-shaped contact spring with clicking action having the superior electrical stability in the contact of a movable contact part and a fixed contact part of the contact spring without curtailing the service life of the contact spring in repeatedly operating the contact spring with the clicking action. SOLUTION: In this switch where an outer surface of the dome-shaped contact spring 3 with the clicking action is fixed to an inner face of a sheet 2, an outer peripheral part of the contact spring 3 is brought into contact with a contact piece 12 of a base 4, and the inner central part of the contact spring 3 made as a movable contact part 8 is brought into contact with or separated from a fixed contact part 13 of the base for electrically switching on and off the contact between the movable contact part 8 and the fixed contact part 13, a hollow 9 is formed on the movable contact part 8, and an edge part 10 formed around the hollow 9 is brought into contact with the surface of the fixed contact part 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to audio equipment,
The present invention relates to a signal input switch used for an electric device or an electronic device such as a video device, a communication device, and a measurement device, and particularly to an improvement of a dome-shaped movable contact spring having a click action.

[0002]

2. Description of the Related Art Conventionally, a switch used for a signal input portion of an electric device or an electronic device includes a dome-shaped contact spring having a click action and a fixed contact portion opposed to a movable contact portion inside the contact spring. Have. The movable contact part
In order to prevent poor contact due to surface contact with the fixed contact portion, recently, a movable contact having a hole is often used.

When a switch is operated, the contact spring is elastically deformed by a pressing force acting on the top of the contact spring, and the direction of the warp is reversed under a click action. At the time of this inversion, the outer peripheral edge portion of the hole of the movable contact portion and the fixed contact portion come into contact with each other by line contact, and are electrically turned on,
Generates a signal according to the purpose of the switch. in this way,
Due to the presence of the hole in the movable contact part, the contact between the edge part of the movable contact part and the fixed contact part becomes line contact instead of surface contact, and the contact pressure at the edge part increases for fine dust etc. In addition, the electrical stability of the contact between the movable contact and the fixed contact is greatly improved.

[0004]

A hole is formed in a movable contact portion, and a plate-like spring material is formed into a dome shape. When a dome-shaped contact spring with a click action is manufactured, the spring material is formed after forming. Due to the springback, the contact spring does not have a uniform dome shape, and the movement amount (stroke) as an operation characteristic becomes large. When the contact spring is repeatedly used, the tensile stress and the compressive stress applied around the hole are large. And cracks are easily formed around the holes. For this reason, there is a problem that the life of the product is shortened. In particular, this tendency is increasing as the size of the contact springs is becoming smaller.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a contact between a movable contact portion and a fixed contact portion of a contact spring when a contact spring having a dome shape and a click action is repeatedly operated without reducing the life of the contact spring. To provide a contact spring with a click action that is excellent in electrical stability.

[0006]

SUMMARY OF THE INVENTION In accordance with the above object, the present invention forms a depression in a central portion of a dome-shaped contact spring having a click action, that is, a movable contact portion, and is formed around the depression. The edge of the fixed contact part is brought into contact with the surface of the fixed contact part by line contact, thereby ensuring the electrical stability of the contact between the two and at the same time, by making the movable contact part a hole, This prevents the life of the spring from being shortened.

Specifically, according to the present invention, the outer surface of a dome-shaped contact spring with a click action is fixed to the inner surface of a sheet, and the outer peripheral portion of the contact spring is brought into contact with a contact piece of a substrate. At the same time, the inner central part of the contact spring is used as a movable contact part, and this movable contact part is brought into contact with and separated from the fixed contact part of the substrate, and the state between the movable contact part and the fixed contact part is electrically turned on and off. In such a switch, a recess is formed in the movable contact portion, and an edge formed around the recess is brought into contact with the surface of the fixed contact portion.

Here, the depression is formed as any one of a circle, an ellipse, a polygon, and a star. Also,
The edge portion is formed as a continuous state or a discontinuous state around the depression.

[0009]

FIG. 1 shows an off state of a switch 1 of the present invention, and FIG. 2 shows an on state of the switch. In these figures, the switch 1 is assembled by a sheet 2 of insulating material, a dome shaped contact spring 3 with a click action and a substrate 4. The sheet 2 is an adhesive film such as plastic, for example, PET, and is adhered to the upper surface of the substrate 4 with an adhesive surface in order to arrange the contact spring 3 on the upper surface of the substrate 4 in a positioning state. The contact spring 3 is made of a dome-shaped metal plate as a whole, and is fixed to an inner surface of the seat 2 by an outer surface. In FIG. 1, the seat 2 is provided with a contact spring 3
The opening 14 is formed at a position corresponding to the central portion of the opening, but the opening 14 may be formed according to the purpose of use and application.

As shown in FIGS. 3 and 4 in addition to FIGS. 1 and 2, the contact spring 3 is made of a stainless steel plate having a thickness of about 0.06 mm and a diameter of about 3.5 mm. A skirt portion 6 formed by a conical surface at an outer peripheral edge portion of the dome portion 5 forms an integral dome shape as a whole, and a boundary portion between them is an annular bent portion 7. . The inner central portion of the contact spring 3, that is, the inner central portion of the dome portion 5 is a movable contact portion 8 made of a silver plating layer. The movable contact portion 8 forms a circular recess 9, and an edge around the recess 9. 10 are formed. Since this depression 9 is usually formed simultaneously with the punching and bending of the contact spring 3 by a press machine,
A protrusion 11 is formed on the outer surface corresponding to the depression 9.

The lower end of the skirt 6 of the contact spring 3 is
It is always in contact with, for example, an annular contact piece 12 embedded in the upper surface of the substrate 4 and is in an electrically conductive state. Further, the edge portion 10 of the movable contact portion 8 faces the fixed contact portion 13 buried at the center of the contact piece 12 on the upper surface of the substrate 4, and comes into contact with the fixed contact portion 13 to be in a state of being electrically conductive. Has become.

FIG. 5 is a graph showing the characteristics of the operating load N (vertical axis) with respect to the stroke S (horizontal axis) of the contact spring 3. As shown in FIG. 4, when a normal operating load N acts on the center of the dome portion 5 of the contact spring 3, the stroke S of the movable contact portion 8 (edge portion 10) increases in almost direct proportion. Is the stroke S1 at which the stroke S causes a click action due to the operating load N1.
, The contact spring 3 reverses the direction of the warp due to the click action, and the operating load N is smaller than before.
Also moves in the direction of the same stroke S, and then
With the force corresponding to the small operating load N2, the stroke becomes S2, and the inverted state is maintained. When the operating load N2 disappears, the contact spring 3 reverses again in the reverse direction and returns to the original state.

When the operator presses the top of the contact spring 3 downward, either directly or via the key top 15, the contact spring 3 is elastically deformed in accordance with the operating load N and becomes flat. After the stroke S1 at which the movable contact portion 8 (edge portion 10) causes the click action, the contact spring 3 reverses the direction of the warp with the bent portion 7 as a bending line, as shown in FIGS. The edge 10 of the movable contact 8 is brought into contact with the surface of the fixed contact 13. Thereby, the edge portion 10 of the movable contact portion 8 and the fixed contact portion 13
Are electrically conductive and turned on.

In this ON state, the edge portion 10 of the movable contact portion 8 makes an annular line contact and comes into contact with the surface of the fixed contact portion 13. Therefore, even if fine dust or the like adheres between the contact portions, the contact pressure of the edge portion 10 of the movable contact portion 8 with respect to the fixed contact portion 13 increases, so that the edge portion 10 of the movable contact portion 8 and the fixed contact portion The stability of the contact with the portion 13 is greatly improved, and the electrical characteristics are also improved.

Further, although the bending strain stress at the time of press working remains around the recess 9 due to the formation of the recess 9, the strain stress at the portion of the recess 9 is smaller than the shear strain stress at the time of forming the hole. When the contact spring 3 is elastically deformed, the tensile stress and the compressive stress applied around the depression 9 are smaller than those of the hole. Therefore, cracks are less likely to be formed in the concave portion 9 of the contact spring 3, and the life of the contact spring 3 becomes longer than that of the conventional one. In addition, since the depth of the depression 9 affects the spring characteristics of the contact spring 3, it is preferable to keep the depth of the recess 9 to ２ or less of the plate thickness of the contact spring 3.

The shape of the depression 9 is not limited to a circle, but may be an ellipse, a polygon, a star, or the like as shown in FIG. Also, the depression 9 is shown in FIG.
As shown in (1), the contact spring 3 can be formed by protruding the outer peripheral portion of the movable contact portion 8 serving as the recess 9 in the direction of the fixed contact portion 13. In this case, the edge portion 10 is formed between the raised portion and the depression 9. Incidentally, the depression 9 may have a hemispherical shape. Further, the edge portion 10 is annularly continuous as a preferred example, but may be formed in a discontinuous state.

[0017]

According to the present invention, the edge formed around the recess of the movable contact portion of the contact spring comes into contact with the surface of the fixed contact portion by line contact. The contact pressure of the contact spring is increased, an electrically stable contact state can be secured, and the movable contact part of the contact spring has no hole, so the tensile stress and compressive stress generated around the depression are compared to the hole. Thus, the edge portion is hardly cracked, the life of the contact spring is prolonged, and a stable switching function can be expected for a long time. Therefore, the contact spring of the main part of the present invention is practically useful as a switch element of a type constituted by combining a substrate and a sheet.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a switch of the present invention in an off state.

FIG. 2 is a cross-sectional view of the switch of the present invention in an ON state.

FIG. 3 is a plan view of a contact spring.

FIG. 4 is a sectional view of a contact spring.

FIG. 5 is a graph of stroke-operating load of a contact spring.

FIG. 6 is an enlarged sectional view of a part of a contact state between an edge portion of a movable contact portion of a contact spring and a fixed contact portion.

FIG. 7 is a plan view of a depression of another shape.

FIG. 8 is an enlarged sectional view of a part of another depression.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Switch 2 Sheet 3 Contact spring 4 Substrate 5 Dome part 6 Skirt part 7 Bend part 8 Movable contact part 9 Depression 10 Edge part 11 Protrusion part 12 Contact piece 13 Fixed contact part 14 Opening 15 Key top

Claims (2)

[Claims] 1. An outer surface of a dome-shaped contact spring having a click action is fixed to an inner surface of a sheet, and an outer peripheral portion of the contact spring is brought into contact with a contact piece of a substrate. A movable contact portion, wherein the movable contact portion is brought into contact with or separated from a fixed contact portion of the substrate, and the movable contact portion and the fixed contact portion are electrically turned on / off. A switch formed by forming an indentation on the surface of the fixed contact portion and an edge formed around the indentation. 2. The method according to claim 1, wherein the depression is formed as any one of a circle, an ellipse, a polygon, and a star.
The described switch.