JP3134908B2 - Key switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a keyboard for electronic equipment.
And a key switch used as a device for inputting various data.

[0002]

2. Description of the Related Art Conventionally, keyboards and various data for electronic devices have been developed.
In the device for inputting the data, the central part of the dish-shaped return spring having conductivity on the back of the pressed key is bent against the edge,
There is a device using a key switch in which the back surface of the central portion is brought into contact with the terminal and the terminal is in conduction with the edge. For example, Japanese Utility Model Application Laid-Open No. 56-2021 filed by the present applicant.
Publication No. 8 is one of them.

In the key switch described in that publication, a contact member is pressed into a contact hole penetrating in the key pressing direction,
A conductive dish-shaped return spring is held in the recess, the key is covered over a housing provided with a locking means for preventing the key from coming out, and the center of the return spring is provided by a projection provided on the back surface of the pressed key. The part is bent to conduct.

[0004]

In the structure of the conventional key switch, when the key is pressed, the dish-shaped return spring is pressed against the back surface of the key, causing buckling, and causing the terminal on the housing side to be buckled. Contact. After the contact, the reaction force applied to the contact part of the dish-shaped return spring from the terminal side concentrates on the contact part of the dish-shaped return spring. However, there has been a problem that the flakes are peeled off to cause rust or cracks, resulting in poor contact.

Also, in order to obtain a key switch having a long stroke, the diameter of the dish-shaped return spring must be increased, so that the switch is enlarged in the radial direction of the dish-shaped return spring. There were also points.

The present invention provides a key switch that does not cause a contact failure due to plating peeling or cracking even if contact is repeated, and a key switch that does not increase the diameter of a dish-shaped return spring.
The purpose is to obtain a long key switch.

[0007]

In order to solve the above-mentioned object, in a key switch according to the present invention, the key has a convex portion on the back surface of the pressing surface, and is fitted into the convex portion of the key. A hook-shaped leaf spring having a portion and a contact portion abutting on a central portion of the return spring is provided between the key and the return spring.

[0008]

When the key of the key switch constructed as described above is depressed, the central portion of the dish-shaped return spring is pushed by the abutting portion of the leaf spring, causing buckling, and then applying a contact to the terminal on the housing side. Abut After the contact, the reaction force applied to the contact portion of the dish-shaped return spring from the terminal side is absorbed by the hook portion of the leaf spring, and no large concentrated stress is applied to the contact portion of the dish-shaped return spring. Therefore, the plating does not peel off, causing rust or cracking.

Further, in order to obtain a key switch having a long stroke, it is only necessary to adjust the bent portion of the leaf spring, so that it is not necessary to increase the diameter of the dish-shaped return spring.

Therefore, according to the present invention, there is provided a key switch which does not cause a contact failure due to plating peeling or cracking even if contact is repeated, and a stroke of the stroke without increasing the diameter of a dish-shaped return spring. A long key switch can be obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals.

FIG. 2 is an exploded perspective view showing the structure of the key switch of the embodiment, and FIG. 1 is an enlarged cross-sectional view taken along the line AA in the state where the key switch of FIG. 2 is assembled.

The key switch 1 includes a housing 5 having terminals 2 to 4 constituting terminals, a conductive dish-shaped return spring 6 also serving as a contact portion, and a hook-shaped leaf spring 7.
Key-8.

Each of the terminals 2 to 4 has a U-shape, and as shown in FIG.
a to 2a extending in parallel from both ends of the
4b.

The housing 5 is provided with a flange 10 integrally around the main body 9. A concave portion 11 for positioning the return spring 6 is provided on the upper surface of the main body 9. The terminals 2 to 4 are provided with the contact portions 2 a to 4 a mounted on the bottom surface 11 a of the concave portion 11 and the leg portions 2 b to 4 b protruding outside the flange 7. The contact portions 2a, 4a are provided at the edge of the bottom surface 12a, and the contact portion 3a is provided at the center of the bottom surface 12a. The opposite side walls 9a, 9b (9b is not shown) of the main body 9 are provided with projections 13, 14 which engage with the key 8.

The return spring 6 is positioned in the recess 11 of the housing 5 with its edge contacting the contact portions 2a, 4a.

The key 8 extends from the edge of the pressing surface 8a to the housing 5.
Side wall 8 that has a side wall that covers the main body 9 of
b, 8c (8c is not shown), respectively,
Square holes 15 and 16 are provided for engaging with the projections 13 and 14 of FIG. Further, a convex portion 17 that engages with the leaf spring 7 is provided on the back surface 8d of the pressed surface 8a. Protrusions 13, 14 and square hole 1
The key 8 is slidable with respect to the housing 5 in the pressing direction with respect to the housing 5.

The leaf spring 7 is provided between the return spring 6 and the key 8. The leaf spring 7 has a fitting hole 19 which fits into the projection 17 of the key 8 with a bent portion 18 interposed therebetween. An embossing portion 20 is provided as an abutting portion that abuts on the central portion of 6. The embossed portion 20 has a predetermined flat surface that comes into contact with the central portion of the return spring 6 as shown in FIG.

FIG. 4 is a sectional view when the key switch is pressed. As can be seen from comparison with FIG. 1, the central portion of the return spring 6 is pressed by the leaf spring 7 to abut the contact portion 3a of the terminal 3, and the contact portions 2a of the terminals 2 and 4, the edges of which are in contact. 4a.

FIG. 5 is an explanatory diagram showing the pressing characteristics of the return spring and the leaf spring. (A) shows the pressing characteristic of the return spring,
(B) shows the pressing characteristics of the leaf spring. The vertical axis and the horizontal axis respectively indicate the load (g) and the amount of deflection (mm). The amount of bending of the return spring 6 increases as the load applied to the central portion increases. And when it reaches point a, it buckles,
The central portion starts to sink as if the surface of the rubber ball was pressed down, and the amount of deflection increases despite the decrease in load. When the point b is reached, the amount of bending increases as the load increases again. The return arrow indicates the characteristics of the return state.

As shown in FIG. 5B, the load and the amount of deflection of the leaf spring 7 are almost directly proportional to each other, the point c corresponds to the state shown in FIG. 1, and the point d corresponds to the point a in FIG. , And point e corresponds to the state shown in FIG.

FIG. 6 is an explanatory diagram showing the pressing characteristics of the key switch. Points f, g, and h are points c, c in FIG. 5B, respectively.
Corresponds to d and e.

Next, the operation will be described. Key before pressing
The switch 1 is in the state shown in FIG.
An urging force corresponding to the load indicated by point f acts on the key 8 to push up the key 8, and the edges of the square holes 15 and 16 shown in FIG. The embossed portion 20 of the leaf spring 7 comes into contact with the center of the return spring 6, and FIG.
Is applied to the center of the return spring 6.
The central portion of the return spring 6 does not contact the contact portion 3a of the terminal 3, and the terminals are not electrically connected.

When the key 8 is depressed, the leaf spring 7 begins to bend gradually, and the driving portion 20 applies a load to the central portion of the return spring 6 while sliding the central portion of the return spring 6. Fig. 6
When the point g is reached, the return spring 6 buckles and flexes sharply. The return spring 6 is located just before the side wall of the key 8 comes into contact with the flange 10 of the housing 5, the back surface of the center part contacts the contact part 3 a of the terminal 3, and the edge part contacts the terminal 2.
And 4 between the contact portions 2a, 4a.

When the key 8 is further depressed, the return spring 6 receives an upward reaction force from the contact portion 3a. However, the return spring 6 is absorbed by the bending of the leaf spring 7 so that the return spring 6 comes into contact with the contact portion 3a. No large concentrated stress acts on the part.

When the pressing force reaches a point h in FIG. 6, the side wall of the key 8 comes into contact with the flange 10 of the housing 5, and an excessive pressing force is applied to this contact portion. Therefore, a pressing force exceeding the load corresponding to the point h does not act on the return spring 6 and the leaf spring 7.

Accordingly, a large concentrated stress does not act on the contact portion between the return spring and the terminal, so that the plating does not peel off and rust or cracks do not occur.

[0028]

Since the present invention is configured as described above, it has the following effects.

A hook-shaped leaf spring having an engaging portion that engages with the back surface of the key and a contact portion that contacts the central portion of the dish-shaped return spring is provided between the key and the dish-shaped return spring. The plate spring absorbs the reaction force applied to the return spring from the terminal after the return spring abuts on the terminal, and no large concentrated stress acts on the contact portion between the return spring and the terminal. It does not cause rust or cracking due to peeling, so that contact failure does not occur even if contact is repeated.

Further, in order to obtain a key switch having a long stroke, it is only necessary to adjust the bent portion of the leaf spring, so that it is not necessary to increase the diameter of the dish-shaped return spring. A key switch having a long stroke can be obtained without increasing the diameter.

Further, since a flat portion having a predetermined size is provided at the contact portion of the leaf spring, when the key switch is pressed, the flat portion slides with respect to the dish-shaped return spring, causing wear. Therefore, it is possible to extend the life of the key switch.

[Brief description of the drawings]

1 is an enlarged cross-sectional view taken along the line AA of FIG. 2;

FIG. 2 is an exploded perspective view of the embodiment.

FIG. 3 is an enlarged view of a driving section.

FIG. 4 is a cross-sectional view when pressed.

FIG. 5 is an explanatory diagram showing pressing characteristics of a return spring and a leaf spring.

FIG. 6 is an explanatory diagram illustrating a pressing characteristic of a pressing switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Press switch 5 Housing 6 Return spring 7 Leaf spring 8 Key 17 Convex part 19 Fitting hole 20 Ejection part

Continuation of the front page (56) References JP-A 2-126317 (JP, U) JP-A 56-59731 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 13 / 36 G06F 3/02

Claims (2)

(57) [Claims] 1. A back surface of a pressed key has conductivity.
A key switch for bending a central portion of a dish-shaped return spring against an edge portion and bringing a back surface of the central portion into contact with a terminal to conduct between the terminal and the terminal in contact with the edge portion. A hook-shaped leaf spring having a convex portion on the back surface of the pressing surface and having a fitting portion fitted into the convex portion of the key and a contact portion abutting on a central portion of the return spring. A key switch provided between the key switch and the return spring. 2. The key switch according to claim 1, wherein said contact portion of said leaf spring is a stamping portion having a predetermined plane.