JPH0455384Y2 - - Google Patents

Description

[Detailed description of the invention] <Field of industrial application> The present invention relates to an electric switch that becomes conductive when a pressing force is applied to the key top and automatically returns to a non-conductive state when the pressing force is released. The present invention relates to a push-type switch that can prevent switch components from deforming due to high temperatures when the switch is soldered into an electric circuit board.

<Conventional technology> Conventionally, the key top of a push-button switch, which is fixed to an electric circuit board by soldering, is made of a synthetic resin molded product, and in order to improve its appearance, it is plated with resin to give it a metallic luster. It's out.

<Problems to be solved by the invention> However, in the above-mentioned key top, when soldering inside the electric circuit board,
In recent years, the so-called reflow method has become more common, but in this method the switch body becomes hot and the key top also becomes deformed due to the high temperature. In order to prevent the above deformation, a highly heat resistant resin such as PPS or PBT resin is used, but it is not easy to chrome plate it. In addition, the cost required for surface treatment increases, which causes an increase in costs.

In other words, for synthetic resin molded products used for key tops, the heat resistance of the synthetic resin and the plating cost of this synthetic resin conflict, and synthetic resin molded products (ABS resin), which can be plated at low cost, are deformed. so it can't be used.

This idea was devised in view of the above circumstances.
The purpose of the present invention is to provide a push switch whose key top is not deformed during a reflow soldering process.

<Means for Solving the Problems> The push-type switch according to the present invention has a body in which a plurality of terminals and fixed contacts are insert-molded, the fixed contacts are exposed in a recess, and a substantially shallow cap-shaped elastic body. a conductive snap plate placed in the recess; a substantially button-shaped key top made of conductive metal; and a key top interposed between the key top and the snap plate to connect both. an electrically conductive frame attached to the body to attach the key top, the snap plate, and the insulating plate to the body; the frame is provided with an earth connection terminal; It is electrically connected to the key top.

<Function> When a pressing force is applied to the key top, the snap plate deforms downward through the insulating plate and comes into contact with the fixed contact piece, making it conductive.On the other hand, when the pressing force is released,
The snap plate returns to its separated state due to its elasticity.

The key top is always grounded together with the frame while not receiving any pressing force.

<Example> Hereinafter, an example according to the present invention will be described with reference to the drawings.

FIG. 1 is an exploded perspective view of a push switch according to the present invention, FIG. 2 is a sectional view of the push switch, and FIG. 3 is a circuit diagram of the push switch.

10 is a body made of synthetic resin such as epoxy resin. This body 10 has a plurality of terminals 11 protruding outward from both side walls, and a body 10.
Fixed contact pieces 13 and 14 are insert-molded and fixed in a recess 12 formed in the center of the holder.
Further, a notch is formed in the vertical inner wall surface of the recess 12, into which a snap plate 20, which will be described later, is inserted.

Reference numeral 20 denotes a circular snap plate having an approximately shallow cap shape and having an inverting function, and is made of a silver-clad phosphor bronze plate with silver contact portions.

30 is a heat-resistant insulating plate, which is attached to the snap plate 2.
It is formed in a size that covers 0.

Reference numeral 40 denotes a frame formed by pressing a tin-plated steel plate, etc., and an opening 41 in the center thereof through which a knob 53 of a key top 50 (described later) passes vertically.
A ground connection terminal 4 is formed protruding from one side.
2 and the two sides sandwiching the ground connection terminal 42 are each provided with a locking opening 43 that fits into a protrusion 15 formed on the body 10.

Reference numeral 50 denotes a key top made of conductive metal, such as chrome-plated brass. The center part thereof has a downwardly directed protrusion 51, the periphery has a series of horizontal collars 52, and the upper part has an opening 41 of the frame 40.
A knob 53 is provided which projects further upwards.

The above-mentioned components are assembled as follows.

Insert the snap plate 20 to which the insulating plate 30 is attached into the recess 12 of the body 10, then place the key top 50 on the snap plate 20, place the frame 40 on the key top 50, and then tighten the knob 53. It is made to protrude from the opening 42.

The frame 40 is fixed to the body 10 by fitting the locking opening 43 into the protrusion 15 of the body 10.

Further, a protrusion 51 facing downward of the key top 50
is in contact with the snap plate 20 via the insulating plate 30, and the key top 50 is always pushed upward. The collar 52 of the key top 50 abuts against the periphery of the opening 41 of the frame 40, and the frame 40 prevents the key top 50 from slipping out upward, and the key top 50 is maintained at a ground potential.

When the key top 50 is pressed, the snap plate 20 deforms downward and comes into contact with the fixed contact pieces 13 and 14, making them conductive. When the pressing force is released, the snap plate 20 is separated by its elasticity. return to the state.

In order to securely attach the push-type switch assembled as described above to the electrical circuit board, each terminal of the push-type switch and the corresponding terminal of the electrical circuit board must be soldered and brought into contact with each other in advance. Then, they are placed in a furnace and heated to a predetermined temperature. This heating melts both solders and electrically and mechanically connects them.

Note that if an alloy such as aluminum is used for the key top, it can be used as is without plating.

Further, in the above description, the insulating plate 30 is attached to the snap plate 20, but an insulating layer may be formed on the lower surface of the protrusion 51 of the key top 50.

<Effects of the invention> According to the push switch according to the invention, the following effects can be achieved by making the key top conductive.

Because it has high heat resistance, it can be used even at temperatures that would deform synthetic resins, especially when performing reflow soldering.

Since the keytop is connected to the ground circuit through the frame, it has good conductivity and does not accumulate static electricity, so it will not be subjected to static shock due to manual operation.

Since the key top is made of metal,
In cases where plating is required, the cost of plating can be reduced because surface treatment is not required.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a push switch according to the present invention, FIG. 2 is a sectional view of the push switch, and FIG. 3 is a circuit diagram of the push switch. 10...Body, 11...Terminal, 13, 14...
...Fixed contact piece, 20...Snap plate, 30...
...Insulating plate, 40...Frame, 42...Earth connection terminal, 50...Key top.

Claims (1)

[Scope of utility model registration request] A body in which a plurality of terminals and fixed contacts are insert-molded, and the fixed contact piece is exposed in a recess, and a conductive snap plate made of a substantially shallow cap-shaped elastic body and placed in the recess. a substantially button-shaped key top made of conductive metal; an insulating plate interposed between the key top and the snap plate to insulate them; and an insulating plate attached to the body to connect the key top and the snap plate. 1. A push-type switch comprising: an insulating plate; and a conductive frame for attaching the insulating plate to the body, the frame having a ground connection terminal formed thereon and electrically connected to the key top.