JPS6129023A - Coil spring for key switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a key switch used, for example, in the keyboard of an electronic cash register or a personal computer, and in particular, the present invention relates to a key switch that is incorporated into this type of key switch. Concerning coil springs.

<Background of the Invention> As shown in FIG. 6, a conventional key switch of this type includes a guide tube 9 that is fixedly attached to a key mounting plate 90, and a key plunger that is disposed within the guide tube 9 so as to be able to freely slide back and forth. 91, a spring seat 93 made of silicone rubber fitted into the lower end opening of the guide tube 9, and a first key plunger 91 for raising and returning the key plunger 91 disposed on the spring seat 93 in the guide *9. , a second coil spring 95 for pressing the switch operation part 92 of the spring seat 93 downward, and a key top 96 attached to the upper end of the key plunger 91. . Thus, in the illustrated key switch, two types of coil springs are required, one each, which causes an increase in the number of key switch components. For this reason, it is necessary to separately manage each coil spring as a part, and when assembling, it is necessary to perform work such as positioning for each coil spring, which causes problems such as a decrease in work efficiency.

<Object of the Invention> The present invention aims to reduce the number of parts in a key switch, and to provide a new coil spring for a key switch that can simplify and improve the efficiency of assembly work, and can be made thinner in shape. With the goal.

It is also an object of the present invention to provide a coil spring for a key switch with excellent characteristics, which can realize a good pressurizing operation of the switch contact and can be expected to have a good expansion and contraction movement without buckling of the key pressing blade. What is the purpose?

<Structure and Effects of the Invention> In order to achieve the above object, the coil spring for a key switch of the present invention is formed so that the winding diameter is small at approximately the center portion, and the pitch increases from this small winding diameter portion toward both ends. It is characterized by being large and made by continuously winding a single spring wire from one end to the other with a large winding diameter.By configuring it in this way, the two coils in the conventional example are By unifying the spring, the number of parts in the key switch can be reduced, which makes it easier to manage the switch components. Also, during assembly, the number of steps such as positioning the coil spring is reduced, simplifying the work. Efficiency can be achieved. In addition, since we have specially provided a small diameter part for switch operation, the pressing force is concentrated on the small diameter part, and it is possible to achieve good contact pressurization action against the switch plate, and also to ensure that the key pressing blade does not buckle. It has the remarkable effect of achieving the first objective of the invention, such as being able to expect expansion and contraction movements.

<Description of Embodiments> FIG. 1 shows an example of the configuration of a key switch. The illustrated key switches IA and IB are inserted into a support 2 attached to the switch plates 1 to 7 and a cylindrical inner hole 8 of a guide cylinder 3 integrally provided with the support 2 so as to be able to reciprocate and slide. A key plunger 4, a key top 9 fitted into the upper end of the key plunger 4, and a coil according to the present invention interposed between the key plunger 4 and the switch plate 7 in the cylinder bore 8 of the guide cylinder part 3. It consists of a spring 5. The switch plate 7 and the support body 2 are arranged such that the pair of legs 3A of the guide cylinder portion 3 are inserted into the locking hole 7A provided in the switch plate 7, positioned and locked (and the pair of legs 3A are inserted into the locking hole 7B). After the stop portion 3B is inserted and positioned, a portion of the protruding lock portion 3B protruding toward the front side of the switch plate 7 is fixed to each other by caulking.Furthermore, the key plunger 4 and the guide cylinder portion 3 are A pair of legs 3 of the guide tube 3
A pair of locking claw legs 4A of the key plunger 4 are slidably engaged in respective guide grooves a provided inside the guide grooves A, so that the upper end of the guide groove 3a and the locking claw legs 4A collide with each other. By contacting the key plunger 4 with respect to the switch plate 7, the amount by which the key plunger 4 is displaced upward is restricted. The coil spring 5 has a narrow winding diameter portion 5C having a narrowed shape by reducing the winding diameter at the substantially central portion, and the pitch increases from the small winding diameter portion 5C toward both ends 5a and 5b, respectively. In addition, one end 5a has a large winding diameter.
It is formed by continuously winding a single spring wire from one end to the other end.

The upper conical spring portion 5A of the coil spring 5
One end 5a is fixedly placed on the spring seat 4B of the key plunger 4, and by constantly urging the key plunger 4 upward, the key plunger 4 is raised and returned to the standby position during a key depression operation. Further, the small diameter portion 5C is a portion that protrudes downward when a key is pressed and comes into contact with the switch plate 7, and the lower conical spring portion 5B presses the small diameter portion 5C against the switch plate 7.

Further, the switch plate 7 on which the coil spring 5 is pressed has a substrate 70 printed with a wiring pattern having a fixed contact portion 71 and a movable contact portion 72 as shown in FIG. The flexible sheet 73 has a spacer 74 pasted around the contact portion 72.

The flexible sheet 73 has a movable contact section 7 on the fixed contact section 71.
2 is superimposed on the upper surface of the substrate 70 so that the small diameter portion 5C of the coil spring 5 is positioned by pressing the key.
When the flexible sheet 73 is pressed as shown in FIG. 3, the movable contact portion 72 comes into contact with the fixed contact portion 71 and becomes a “contact portion” state.

Therefore, by setting the diameter of the small diameter portion 5C of the coil spring 5 to be small, the pressing force is concentrated on the small diameter portion 5C, and a good contact pressing operation against the switch plate 7 can be realized.

In the case of the illustrated coil spring 5, the small diameter portion 5C
The diameter of each end portion 5a, 5b is set to 3.5, and a -F portion circular armor spring portion 5A and a lower conical spring portion 5B are respectively formed, and each end portion 5a, 5b has a diameter of 1. A reinforcing portion is formed by closely winding the coil about three times around the small diameter portion 5C.

In the key switches IA and IB configured in this way, after the key plunger 4 is inserted into the guide cylinder part 3 of the support body 2, the key top 9 is fitted and fixed to the upper end of the key plunger 4, and then , the coil spring 5 is inserted into the lower end opening of the key plunger 4, the upper end 5a is positioned on the spring seat of the key plunger 4, and then the support body 2 is fixed to the switch plate 7, thereby assembling. Under this state, the lower conical spring portion 5B and the upper conical spring portion 5A of the coil spring 5 are compressively deformed, and the small diameter portion 5C is disposed in a position extremely close to the switch plate 7.

Thus, when key top 9 is depressed, key plunger 4
As the upper conical spring portion 5A is lowered, the upper conical spring portion 5A is further compressed and deformed, whereby the small diameter portion 5C is brought into contact with the switch plate 7 and the “contact closed” state is created.

FIG. 5 shows the key suppression operation characteristics for the coil spring 5. In the figure, Fa indicates the pressing force acting on the coil spring 5 under the initial state, and when this pressing force is increased from Fa to Fg and the key plunger 4 is moved by a stroke S along the cylinder inner hole, This is to obtain a "contact closed" state.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of a key switch incorporating the coil spring of the present invention, Figs. 2 and 3 show the operation of the switch plate, and Fig.
Figure 4 is a front view showing the coil spring of the present invention, Figure 5 is an explanatory diagram showing the pressing characteristics of a key switch, and Figure 6 is a sectional view showing a conventional key switch. IA, IB...key switch, 5...coil spring, 5A...upper conical spring part, 5B...lower conical spring part, 5C...small diameter part, 5a, 5b... ·edge.

Claims (1)

[Claims] The winding diameter is formed to be small at the approximately center portion, and the pitch increases from this small winding diameter portion toward both ends, and
A coil spring for a key switch is made by continuously winding a single spring wire from one end to the other so that it has a large winding diameter.