JPH077038U - Key switch - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a key switch that can be normally operated even if a pressing force is applied to the end of the key top. [Structure] The pressing force applied to the key top 1 is applied to the membrane switch SW via the dome state 4A formed on the embossed sheet 4 to turn on the membrane switch SW,
In the key switch of the structure for turning off, a small projection 4B that engages with the peripheral edge of the key top 1 is provided around the dome-shaped body 4A provided on the embossed sheet.
By engaging with the peripheral edge of the back surface of the key top 1,
Even if a pressing force is applied to the end of the key top, the key top does not fall down, and the dome-shaped body 4A is pressed down at the center of the key top so that the switch operation can be performed reliably.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

[0002]

[Prior art]

 The applicant of the present application proposed a key switch having a structure as shown in FIG. 7 by the name of “Japanese Patent Application No. Hei 5-30881: Support structure of key top and key switch”. This invention is an improvement of the structure of the previously proposed key switch. However, we are trying to propose a key switch that is easy to use.

In the key switch proposed above, a flat key top 1 is attached to a flexible transparent film sheet 2. The transparent film sheet 2 is laminated on the upper surface of the light guide plate 3 which also functions as a spacer. A hole 3A having an area larger than the shape of the key top 1 is formed in the spacer / light guide plate 3, and the key top 1 is arranged above the hole 3A. On the back side of the transparent film sheet 2, a protrusion 1A is formed at approximately the center of the key top 1. The protrusion 1A is formed of, for example, a photocurable resin material. The protrusion 1A faces the apex of the dome-shaped body 4A formed on the embossed sheet 4, and when the key top 1 is pushed down, the dome-shaped body 4A is pushed down, and when the amount of deformation thereof exceeds a predetermined value, the dome-shaped body is formed. The body 4A is inverted so as to be convex downward, and the reaction force causes the membrane switch SW provided on the lower side to be turned on.

A printed wiring board 6 is arranged on the lower surface of the membrane sheet 5 which constitutes the membrane switch SW. A light source 7 such as a light emitting diode is mounted on the printed wiring board 6, and the light source 7 is engaged with the recessed hole 3B formed in the spacer / light guide plate 3 so that the light from the light source 7 is incident on the spacer / light guide plate 3. This light is guided through the transparent film sheet 2 to the key top 1 on which a transparent plate is formed, and the key top 1 is illuminated, and the function display portion printed on the surface of the transparent film sheet 2 is illuminated and given to the key top 1. Display the selected function.

Reference numeral 8 denotes a case of the device. A window 8A for exposing the keytop 1 is formed in the case 8 of the apparatus, and the keytop 1 is projected to the outside through the window 8A so that the keytop 1 can be pressed.

[0006]

[Problems to be solved by the device]

 The key switch previously proposed has a structure in which the dome-shaped body 4A is simply formed on the embossed sheet 4. For this reason, as shown in FIG. 8, when the end portion of the key top 1 is pushed down, there is a disadvantage that the membrane switch SW is not turned on only when the key top 1 is tilted.

That is, when the key top 1 is tilted and operated, the load P applied to the key top 1 is a load P ₁ sufficient for the dome-shaped body 4A to be inverted downward as shown in FIG. Although the key top 1 is reached, the pressing force F is not transmitted from the key top 1 to the center of the dome-shaped body 4A, so it is considered that the dome-shaped body 4A stops without being inverted.

An object of the present invention is to propose a key switch having a structure that does not cause such an inconvenience.

[0009]

[Means for Solving the Problems]

 In this device, the key top is formed on the embossed sheet in the key switch structure in which the dome-shaped body formed on the embossed sheet is pushed down by the key top and the direction of the dome-shaped body is reversed to operate the membrane switch in the ON state. It has a structure in which small protrusions are provided around the circumference of the dome-shaped body that engages with the peripheral edge of the key top.

According to the structure of the present invention, even if a pressing force is applied to the end of the key top, the peripheral edge of the key top engages with the small protrusion. As a result, the key top does not fall down greatly and is pushed down while maintaining a substantially horizontal state. As a result, the pressing force is concentrated on the center of the key top by the reaction force from the small protrusions even though the pressing force is applied to the end of the key top, and the pressing force can be applied to the dome-shaped body of the embossed sheet. Regular switch operation is possible.

[0011]

【Example】

 FIG. 1 shows an embodiment of this invention. The parts corresponding to those in the drawings are designated by the same reference numerals, and detailed description thereof will be omitted, but in the present invention, the periphery of the dome-shaped body 4A formed on the embossed sheet 4 (the position that engages with the back surface of the key top 1) ), A small protrusion 4B is formed. In the example shown in FIG. 2, four small projections 4B are formed around the dome-shaped body 4A, but the number is not limited. The shape is not limited to the dome shape, and may be linear as shown in FIG. Further, in the case of a round key top, the small protrusions 4B can be formed in a ring shape as shown in FIG.

If the curvature of the upper surface of the small protrusion 4B is small, the strength of the small protrusion 4B can be increased. By making the strength of the small projection 4B strong, even if the small projection 4B is pushed by the key top 1, the small projection 4B does not collapse. As a result, as shown in FIG. 5, even if a pressing force P is applied to the end of the key top 1, the small protrusions 4B are not crushed. Therefore, the key top 1 is pressed without tilting and the protrusion 1A provided at the center causes the key top 1 to move. A pressing force can be applied to the comb-shaped body 4A. FIG. 6 shows the characteristics of the load P and the displacement S of the key switch according to the present invention. FIG. 6 shows the characteristic that the membrane switch SW is normally operated due to the presence of the small protrusion 4B. Point A shown in FIG. 6 indicates a point at which the membrane switch SW is turned on.

[0013]

[Effect of device]

 As described above, according to the present invention, since the small protrusion 4B is provided around the dome-shaped body 4A formed on the embossed sheet 4, the key top 1 is largely tilted even if the pressing force P is applied to the end of the key top 1. Without being pushed, the pressing force can be kept horizontal and the pressing force can be concentrated on the projection 1A provided at the center of the key top 1 by the reaction force received from the small projection 4B. As a result, even when the pressing force P is applied to the end of the key top 1, the key top 1 can reliably apply the pressing force to the dome-shaped body 4A, so that the membrane switch SW can be reliably turned on. can do.

Therefore, there is an advantage that a key switch having good operability and high reliability can be provided. When this invention is applied to the previously proposed key switch, since the transparent film sheet 2 to which the key top 1 is attached is an integral sheet without holes, it is possible to obtain a key boat with high waterproofness and dust resistance. it can.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view for explaining the embodiment of the present invention shown in FIG. 1 in detail.

FIG. 3 is an exploded perspective view showing another example of the main part of the present invention.

FIG. 4 is an exploded perspective view showing a modified embodiment of the present invention.

FIG. 5 is a sectional view for explaining the function and effect of the present invention.

FIG. 6 is a graph for explaining the function and effect of the present invention.

FIG. 7 is a sectional view for explaining the prior art.

FIG. 8 is a cross-sectional view for explaining the drawbacks of the prior art.

FIG. 9 is a graph for explaining the operation of the prior art.

[Explanation of symbols]

 1 key top 2 transparent film sheet 3 spacer and light guide plate 4 embossed sheet 4A dome-shaped body 4B small protrusions 5 membrane sheet SW membrane switch 6 printed wiring board 7 light source

Claims (2)

[Scope of utility model registration request] 1. A. The pressing force applied to the key top is applied to the dome-shaped body formed on the embossed sheet, the shape of the dome-shaped body is inverted to a convex state downward, and this reversal turns on the membrane switch provided under the embossed sheet. In the key switch structured to operate in the state of B. A small protrusion is provided around the dome-shaped body, and even if a pressing force is applied to the end of the key top, the small protrusion engages with the key top, and the reaction force from the small protrusion causes the dome to be located at the center of the key top. A key switch with a structure for pressing the state. 2. A flexible sheet is placed over the hole formed in the spacer, and a keytop is attached to this sheet, and the flexibility of the sheet causes the keytop to move vertically. Claim 1 configured to be capable
Key switch described.