JPH04235443A - Key switch structure for telephone set - Google Patents

Abstract

PURPOSE:To reduce thickness without losing a click feeding. CONSTITUTION:A membrane switch 33 equipped with an elastic disks 33b consisting plural thin plates is provided on a printed circuit board 31, plural recessed parts 36b corresponding to the elastic discs 33b of the membrane switch 33 is integrally molded with the back of the membrane switch, a key top sheet 36 with characters and symbols printed on its surface is placed on the printed circuit board 31, and the recessed part 36b of the applicable key to sheet 36 is formed to a shape and hardness so as to give a click feeding when the membrane switch 33 is changed-over.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key switch structure for telephones such as automobile telephones and mobile telephones.

[0002] Needless to say, the ultimate purpose of communication is to be able to immediately convey or exchange intentions or information with anyone at any time, from anywhere, and in addition to conventional fixed point-to-point communication, mobile communication is gradually developing. Mobile communication is communication between moving objects (including people) such as ships, automobiles, and airplanes and general subscriber telephones, offices, etc., and communication between mobile objects.In recent years, it has become a type of mobile communication. Car phones and mobile phones are being actively developed.

[0003] Such car phones and mobile phones are required to be smaller and thinner from the viewpoint of portability, and the key switches installed for performing various input operations are also required to be smaller and thinner. At the same time, ergonomic considerations are also required to ensure reliable operation.

0004

2. Description of the Related Art FIG. 3 is a perspective view showing the appearance of a general handset in a car telephone. handset 2
A keyboard in which a receiver and a transmitter are ergonomically arranged at a predetermined distance on one side of the 0, and a plurality of key switches for performing dial operations etc. are arranged on the other side. 10 and a liquid crystal display for displaying information. The handset 20 is connected by a cable to a main body that includes a transmitting and receiving device.

FIG. 4 is an exploded perspective view showing the structure of a conventional key switch, and FIG. 5 is a sectional view thereof. In the same figure,
11 is a printed circuit board, on which a plurality of switch circuit patterns (not shown) are formed and a plurality of light emitting diode chips 13 are arranged.

Reference numeral 12 denotes a rubber switch, and the rubber switch 12 is formed by arranging a plurality of protrusions 12b and a plurality of through holes 12d that can be restorably depressed into the base sheet 12a. They are arranged at positions corresponding to the switch circuit pattern and the light emitting diode chip 13 formed on the printed circuit board 11, respectively.

Reference numeral 14 denotes a light guide plate. The light guide plate 14 has a light transmitting property, and has a plurality of through holes 14a through which the convex portion 12b of the rubber switch 12 passes, and a recess for receiving the light emitting diode chip 13 on the printed circuit board 11. 14b. 16 is a rubber sheet, and the rubber sheet 16 has a key top portion 16a on which characters and the like are printed. The rubber sheet 16 is attached to the light guide plate 14 by the double-sided adhesive sheet 17.
is glued to.

However, when the key top portion 16a of the rubber sheet 16 is pressed, the contact portion formed on the bottom surface of the convex portion 12b of the rubber switch 12 comes into contact with the switch circuit pattern formed on the printed circuit board 11. The corresponding switch circuit is closed and a switching operation is performed. Furthermore, when the light emitting diode chip 13 is turned on at night, etc., the light emitted from the light emitting diode chip 13 passes through the inside of the light guide plate 14 and is guided to the back side of the rubber sheet 16, illuminating the rubber sheet 16 from the back side. It is supposed to be done.

[0009]

[Problems to be Solved by the Invention] However, conventionally used rubber switches require a stroke of at least 0.8 mm in order to perform a reliable switching operation, depending on their configuration. There is a problem in that there is a limit when considering thinning.

[0010] Also, when a rubber switch is operated (pressed down), there is little click feeling (the vibration generated when the switch is pressed and the user recognizes through the fingertips that a switching operation has been performed), and especially if the stroke is made small, there is no click sensation at all. In some cases, there is a problem in that reliable operation cannot be expected from an ergonomic point of view.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a key switch structure that can be made thinner without sacrificing the above-mentioned click feeling.

0012

[Means for Solving the Problems] A membrane switch is provided on a printed circuit board, and includes a plurality of thin elastic disks, and performs a switching operation by deformation of the elastic disks, and the membrane switch is mounted on the back surface of the membrane switch. A key top sheet on which a plurality of convex portions corresponding to the elastic discs are integrally molded and characters and symbols printed on the surface thereof is placed on the printed circuit board, and the convex portions of the key top sheet are placed on the printed circuit board. The shape and hardness are such that the membrane switch produces a click feeling when switching.

[0013]

[Operation] A membrane switch forms a terminal pattern on a printed circuit board that is insulated from other patterns at least on its surface, and attaches a thin elastic disc with a depressed center to the terminal pattern. This switch is arranged so that they face each other, and when the elastic disk is pressed down, the elastic disk is deformed so that it can be restored, and the contact between the elastic disk and the terminal pattern is detected, and the stroke is 0.5 mm or less (
~0.2 mm), which is smaller than the stroke of a conventional rubber switch, and can achieve a thinner profile.

[0014]Furthermore, the membrane switch can provide a click feeling when pressed through a member having a certain degree of hardness, and in the present invention, when the membrane switch switches on the back side of the key top sheet, a click feeling can be obtained. It is constructed by integrally molding a convex portion with a shape and hardness that gives a comfortable feeling, and can be expected to ensure reliable operation from an ergonomic standpoint.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing essential parts of an embodiment of the present invention, and FIG. 2 is an exploded perspective view.

In the figure, 31 is a printed circuit board, and on the printed circuit board 31, although not shown, a plurality of terminal patterns are formed and arranged, and a plurality of light emitting diode chips 32 are arranged. There is. Reference numeral 33 designates a membrane switch. The membrane switch 33 has through-holes formed at positions corresponding to the terminal patterns formed on the printed circuit board 31 of a base sheet 33a made of a polyester film, and a disk made of stainless steel is formed in each through-hole. 33b, and a through hole 33c is formed at a position corresponding to the light emitting diode chip 32 on the printed circuit board. The disk 33b is an elastic member formed so that its central portion is depressed, and by pressing down the vicinity of the central portion, the disk 33b
b deforms and contacts the terminal pattern formed on the printed circuit board 31 in a restorable manner.

Reference numeral 34 denotes a light guide plate having optical transparency, and the light guide plate 34 connects each disk 33b of the membrane switch 33.
It has a plurality of through holes 34a facing each other, and a recess 34b for receiving the light emitting diode chips 32 arranged on the printed circuit board 31. 36 is a key top sheet having a plurality of key top parts 36a, characters etc. are printed on the surface of each key top part 36a, and a plurality of convex parts 36b having a predetermined hardness are integrally molded on the back side. There is.

37 is a convex portion 36b of the key top sheet 36
The key top sheet 36 is a double-sided adhesive sheet having through holes 37a at positions corresponding to the respective positions, and the key top sheet 36 is adhered to the light guide plate 34 by this double-sided adhesive sheet 37. The light guide plate 34 to which the key top sheet 36 is adhered is fixed together with the membrane switch 33 to a printed circuit board 31 fixed to a case 40 of the handset with a plurality of screws 38.

The key top sheet 36 described above is molded using a rubber-based resin, and is molded by film transfer molding (in-mold method). And key top sheet 3
The hardness of the convex portion 36b formed on the back surface of 6 can be, for example, 70 degrees, and the height in the protruding direction can be about 1 mm.

When the key top portion 36a of the key top sheet 36 is pressed down, the convex portion 36b of the key top sheet 36 causes the disc 33b of the membrane switch 33 to be pressed down.
is deformed and a switching operation is performed.

According to this embodiment, the membrane switch 3
3 is adopted, and this membrane switch is pressed down via a protrusion 36b of a predetermined hardness that is integrally molded on the back surface of the key top sheet 36, so a reliable click feeling can be obtained and erroneous operation can be avoided. You can expect reliable operation without any problems. Further, since the membrane switch 33 has a stroke of 0.5 mm or less (~0.2 mm), which is smaller than a conventional rubber switch, it is possible to construct a thin keyboard as a whole. Furthermore, since the distance between the key top sheet 36 and the light emitting diode chip 32 arranged on the printed circuit board 31 also becomes closer, a sufficient amount of light can be obtained on the surface of the key top sheet 36, making it possible to use it even at night. The key top portion 36a can be easily recognized visually.

Furthermore, by employing a rubber-based resin as the material for the key top sheet 36, the strength is improved, and molding by an in-mold method is possible, so that the flexibility of the design can be improved.

[0023]

As described above, the present invention has the advantage that it is possible to reduce the thickness of the key switch without impairing the click feeling.

[Brief explanation of the drawing]

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

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

FIG. 3 is a perspective view of a typical handset.

FIG. 4 is an exploded perspective view of the prior art.

FIG. 5 is a cross-sectional view of the prior art.

[Explanation of symbols]

31 Printed circuit board 33 Membrane switch 34 Light guide plate 36 Key top sheet 36b Convex part

Claims (1)

[Claims] [Claim 1] A plurality of thin elastic disks (33b).
a membrane switch (33) which performs a switching operation by deforming the elastic disc (33b).
is provided on the printed circuit board (31), and a plurality of convex portions (36b) are integrally molded on the back surface thereof corresponding to the elastic disc (33b) of the membrane switch (33), and characters and symbols are printed on the surface thereof. A printed key top sheet (36) is placed on the printed circuit board (31), and when the membrane switch (33) switches the convex portion (36b) of the key top sheet (36). A key switch structure for a telephone, characterized by having a shape and hardness that produces a click feeling.