JPH0320985Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a key switch, and more particularly to a key switch in which legs and guide pins provided on a press key are slidably disposed in a through hole bored in a substrate such as a printed board.

As a conventional key switch, the one shown in FIG. 1 is known. That is, a substrate 1 such as a printed board
Fixed electrodes are patterned on the legs 4a, 4a, which are provided on a substantially rectangular parallelepiped-shaped casing 4 made of synthetic resin.
A through hole 3 for inserting the casing 4 is made in the substrate 1, and the casing 4 is inserted into the substrate 1 by means of protruding pieces 4b, 4b having sloped portions provided at the tips of the legs 4a, 4a.
It is designed to be fixed in place.

The upper surface of the casing 4 has a through hole 4c into which the press key 5 is inserted. The press key 5 is made of a synthetic resin material and has a convex shape, and the press part 5a of the press key 5 projects a through hole 4c on the upper surface of the casing 4 from the inside of the casing 4, and serves as a press for pressing the elastic member 6 of the press key 5. The width W of the piece 5b is selected so that it can freely slide up and down inside the casing 4.

The elastic member 6 is made of rubber or the like and is approximately cup-shaped. The legs 6a of the cup-shaped portion are sandwiched between the lower end of the casing 4 and the substrate 1, and the fixed electrode 2 is inserted into the cup-shaped portion. A movable electrode 7 made of conductive rubber or the like is disposed at a position facing the , and a protrusion 6b provided at the top of the cup-shaped portion is in contact with the pressing piece 5b of the pressing key 5, so that the elastic force of the elastic member 6 is The push key 5 is always raised in the direction of arrow U.

In the above-described configuration, when the press key 5 is pressed against the lifting force of the elastic member 6, the cup-shaped portion bends and the movable electrode 7 comes into contact with the fixed electrode 2, forming a switch. This switch structure has the disadvantage that the number of parts increases because it requires the press key 5 and the casing 4 for vertically sliding the press key 5 within the casing 4.

In order to eliminate these drawbacks, the present applicant has developed a push key 8 that combines a conventional push key and a casing.
A key switch as shown in FIG. 2 has been proposed in which the key switch can be slid vertically into a through hole 3 of a substrate 1.

That is, in FIG. 2, the press key 8 is formed of synthetic resin or the like in a substantially rectangular shape, and has legs 8a, 8a at the lower end similar to that shown in FIG. It has protruding pieces 8b, 8b with
By lowering the press key 8 against the lifting force of the elastic member 6, the movable electrode 7 is brought into contact with the fixed electrode 2 to function as a switch.

However, the problem with this configuration is that if the press key 8 is pressed unevenly as shown by arrow D in FIG.
The movable electrode 7 may not be able to be brought into contact with the switch, which has the disadvantage that a reliable switch operation cannot be performed. In addition, there was a keyboard (Utility Model Publication No. 53-28049) in which a rod-shaped guide was suspended below the press key and was engaged and supported by a guide tube provided on the printed wiring board in order to prevent uneven pressing of the press key. .

However, since the keyboard supports the press keys by engaging only the two contact operation legs protruding from the left and right sides of the press keys with the dustproof plate placed on the board, the cushioning slack, which is an elastic member, The return by part acts on a part of the pressed key, and as a result,
There is a problem in that the axis of the guide tube and the pin is misaligned, and the push key does not return accurately due to friction therebetween.

Furthermore, depending on the pressing operation of the press key, even after the movable electrode and the fixed electrode are brought into contact,
The so-called on-stroke was short, which also caused contact chattering.

The present invention proposes a key switch that eliminates the above-mentioned drawbacks.The key feature is that the key can be smoothly slid up and down even if the key is pressed in an uneven position, and the switch can be operated reliably. It was made to work. Therefore, in the present invention, a center hole is bored in the center of the top of a cup-shaped elastic member that is housed in the cavity of the press key and holds the key top position at a predetermined height, and is concentric with the center hole. A cylindrical elastic protrusion is provided so that the elastic protrusion comes into contact with the top of the inner wall of the press key, and a central through hole of the elastic member and a guide provided in the substrate are provided in the center of the press key. A straight bar-shaped guide body that is inserted into the through hole and guides the key top parallel to the substrate is integrally provided, and the key top is moved parallel to the substrate when pressed.

Hereinafter, the present invention will be described in detail based on FIGS. 3 and 4 showing examples thereof.

Note that the same parts as in FIGS. 1 and 2 are given the same reference numerals, and redundant explanation will be omitted.

FIG. 3 shows a key switch showing an embodiment of the present invention, in which a downwardly directed guide pin or the like is integrally formed in the center of the cavity 8d of the press key 8 when the press key is molded, or a metal pin or the like is installed directly. Rod-shaped guide body 8f
The guide body 8f is guided through a through hole 6c formed in the center of the elastic member 6 to a guiding hole 3a formed in the substrate 1.

Therefore, even if the press key 8 is pressed biased in the direction of the arrow D, the press key 8 will not be pressed tilted because the guide body 8f is guided along the through hole 3a of the substrate 1, and the press key 8 will always be pressed smoothly. can be caused to press the press key 8.

Although various shapes are conceivable for the present invention, it is clear that the elastic member is not limited to rubber or the like, but may be an ordinary coil spring or the like, and the shape of the press key may be appropriately selected such as a circular shape or a polygonal shape.

As mentioned above, the present invention reduces the number of parts by omitting the exterior cover and housing, etc., and the press key is fixed to the board to prevent it from coming off. When the press key is pressed, it is tilted and pushed down, resulting in poor contact. It is possible to provide a key switch that does not cause such problems, which has a great practical effect.

In particular, in the present invention, a central through hole is provided at the center of the top of the elastic member, and a cylindrical elastic protrusion is provided concentrically with the central through hole, and the elastic protrusion is brought into contact with the top of the inner wall of the press key. A straight bar-shaped guide integrally protruding from the center of the press key is inserted into the center hole of the elastic member and the guide hole provided on the board, and guides the key top parallel to the board, so that when the key is pressed, The key top can always be moved parallel to the board, and the key can be slid evenly without deviation no matter where the press key is pressed, and a cylindrical elastic protrusion on the top surface of the elastic member is arranged concentrically with the center hole. By providing this and bringing it into contact with the top of the inner wall of the press key,
The contact surface between the top of the inner wall of the press key and the elastic protrusion is annular, and excess pressing force applied to the press key can be absorbed by contraction and deformation of the cylindrical elastic protrusion.
Excessive strain after the movable electrode hits the fixed electrode,
This made it possible to prevent shocks.

As described above, the key switch according to the present invention has good operability without chattering or bouncing, and when pressed, the pressing key presses the elastic member parallel to the board, and when returning, the key top is evenly pressed against the elastic member. It was decided to move parallel to the board and return.

[Brief explanation of drawings]

1 and 2 are side sectional views of a conventional key switch, and FIG. 3 is a partially sectional side view of the key switch of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Fixed electrode, 3... Through hole, 3a... Guide through hole, 4... Casing, 5... Press key, 6...
Elastic member, 6b...protrusion, 6c...center through hole, 7...
Movable electrode, 8...press key, 8a...leg, 8d...cavity, 8f, 9...guide.

Claims (1)

[Scope of utility model registration request] A press key having a hollow portion opened downward and having a plurality of legs provided at the lower end of the periphery thereof, and a substrate having a plurality of through holes through which the plurality of legs are inserted while being prevented from falling out. , a cup-shaped elastic member accommodated in the cavity of the press key to maintain the key top position of the press key at a predetermined height, a movable electrode disposed on a ceiling portion within the elastic member, and the movable electrode. and a fixed electrode disposed on the substrate opposite to the key switch, wherein a central through hole is provided at the center of the top of the elastic member, and a cylindrical elastic protrusion is provided concentrically with the central through hole. bringing the elastic protrusion into contact with the top of the inner wall of the press key;
A straight bar-shaped guide body is integrally provided at the center of the first pressing key to guide the key top parallel to the base plate by being inserted into the center through hole of the elastic member and the guide through hole provided in the base plate. A key switch characterized by: