JPH11213809A - Sheet-like key top - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the sense of clicking of the contact part of a metallic coned disc spring or a resin film dome and the like and to prevent the breakage of the contact part by a residual stress by using a thermoplastic elastomer as the material of the pressing part of a push-button switch. SOLUTION: On the upper surface side of a key top body consisting of a thermoplastic resin 3 such as PE, PP, PS, AS, PMMA, PC, MS, poly(-4- methylpentene) or the like, a film having a display part curved in the same form a printed thereon is formed, and on the lower surface side of the key top, a pressing part formed of a thermoplastic elastomer 6 of styrene, olefin, polyester, polyamide, urethane, vinyl chloride or the like is integrated to the lower surface side of the key top by thermal fusion to form a sheet-like key top for a push-button switch. In the pressing part, the reduction in the sense of clicking after continuous keying and the cracking to a contact part due to the excessively high material hardness of the pressing part can be prevented by imparting rubber elasticity, which is a characteristic of the thermoplastic elastomer 6 thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone, a personal computer keyboard, a controller, an AV device, and a motor input S.
It relates to various key switches such as W.

[0002]

2. Description of the Related Art In general, a push button switch in which a film on which a display portion having the same shape is printed is integrally formed on the upper surface side of a key top body made of a thermoplastic resin molded by a mold, is generally used. The combination of a key top display portion and a pressing portion is mainly used. One-piece products are formed by integral molding, and two-piece products are formed by separate molding.

Hitherto, hardness has been required as a characteristic of a key top display portion, and the purpose is to improve the feel and response.
Translucent thermoplastic resin is used, and the pressing part also requires hardness as a characteristic. It is made of translucent thermoplastic resin, and improves the click characteristics by combining with a metal disc spring. It was necessary to plan. Further, the key top display portion and the pressing portion require a thermoplastic resin as transparent as possible in order to transmit light from a light-emitting body such as an EL or LED.

[0004]

In mounting, a film on which a display portion having the same shape is printed is integrally formed on the upper surface side of a key top body made of a molded thermoplastic resin.
A contact portion such as a metal disc spring or a resin film dome having a click feeling is provided on the lower surface of the push button switch, and when the switch is pressed, the tip of the pressing portion presses the metal disc spring or the resin film dome. .

Therefore, since the pressing portion is formed of a high-hardness thermoplastic resin, when the contact portion is a metal disc spring,
The pressing pressure load after clicking increased, and a load was applied to the substrate below the metal disc spring, and dents were likely to occur on the substrate.

In the case where the contact portion is a resin film dome, the pressing portion has a high resin hardness and there is no stress relaxation due to the pressing force. Cracks occurred in the contact due to residual stress.

[0007]

According to the present invention, the pressing portion of the push button switch is made of a thermoplastic elastomer as shown in FIG. It is intended to provide a sheet-like key top structure characterized by improving the contact and preventing breakage of the contact portion due to residual stress.

[0008] The two can be integrated by any method such as a double-sided tape, an adhesion method using an adhesive, an adhesion method using an adhesive, and a fusion method using heat, ultrasonic waves or the like.

The key top display section is formed by sandwiching a film on which a display section has been printed in advance between the lower and upper molds of the key top display section molding die, and injection-molding a thermoplastic resin. The part is sandwiched by the lower and upper dies of the pressing part forming die, and the film perforated in a predetermined position in advance,
It can be formed by injection molding of a thermoplastic elastomer.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS PE, PP, PS, AS, PMM
A, PC, MS, key top body made of a thermoplastic resin such as poly (-4-methylpentene) or the like is formed on the upper surface side with a film on which a display portion curved to the same shape is printed, and a lower surface of the key top is formed. On the side, a pressing portion formed of a thermoplastic elastomer such as styrene, olefin, polyester, polyamide, urethane, or polyvinyl chloride was integrated by heat fusion to form a sheet-like key top of a push button switch.

When the pressing portion is formed of a material other than the above, a urethane type, an acrylic type, an epoxy type,
The parts are integrated using a PVC or polyester adhesive.

[0012]

Embodiment 1 A method of manufacturing a key top according to FIG. 2 is described. (A) A film 1 which has been printed beforehand is bent into the same shape as a desired key top shape by a die (B). After setting in the molds 8 and 9 (C), the mold is clamped, and then the thermoplastic resin 3 is injection-molded from the gate injection port 4 arranged on the back of the key display unit (D), and integrally molded with the film. The gate is cut simultaneously with the mold opening (E).

Further, a method of integrating the pressing portions will be described with reference to FIG.

The movable mold 9 is used as a common mold, the mold is closed by the secondary fixed mold 10 and the thermoplastic elastomer 6 is removed.
Is injection molded to form a pressing portion to form the push button switch of the present invention.

The gate injection port 5 was disposed on the side projection 7 of the pressing portion.

In the two-piece structure type having the key top display section and the pressing section, the fixing method of the film of the key top display section is not limited, so that the thermoplastic resin of the key top display section and the thermoplastic elastomer of the pressing section are used. However, there is no need for adhesion and fusion.

As the thermoplastic resin for the key top display section,
Polyethylene, polypropylene, polyvinyl chloride, polystyrene, styrene-acrylonitrile copolymer, AB
Thermoplastic resins such as S resin and methacrylic resin, and engineering plastics such as polyamide resin, polyacetal, and polycarbonate are mainly used.

As the thermoplastic elastomer, styrene-based, vinyl chloride-based, olefin-based, polyester-based, polyamide-based, urethane-based and the like are mainly used as a property for imparting rubber elasticity.

[0019]

According to the present invention, the pressing portion is provided with rubber elasticity which is a characteristic of a thermoplastic elastomer, so that the contact portion such as a metal disc spring or a resin film dome having a click feeling on the lower surface of the push button switch can be used. This makes it possible to prevent the click feeling after continuous key tapping due to the excessively high material hardness of the pressing portion and to prevent the contact portion from cracking.

Further, in the conventional one-piece product, the key top printed character portion was easily distorted in the air escape direction of the resin in order to satisfy injection molding conditions for preventing sink marks due to the curing of the thermoplastic resin. Can switch between the injection condition for forming the key top display section and the injection condition for forming the pressing section, so that the quality of the key top display section can be maintained and the pressing section can be formed. The influence of generation is eliminated, which can greatly contribute to improvement in yield.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a sheet-like key top.

FIG. 2 is a view showing a process of forming a keytop.

FIG. 3 is a view showing a step of forming and integrating a pressing portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Film 2 Display part 3 Thermoplastic resin 4, 5 Gate inlet 6 Thermoplastic elastomer 7 Side protrusion

Claims (2)

[Claims] 1. A key press main body made of a thermoplastic resin is integrally formed with a film on which a display portion which is curved in the same shape is printed on an upper surface side, and a convex press used as a presser on a lower surface side of the key top. A sheet-like key top of a push button switch having a portion, wherein the convex pressing portion is formed of a thermoplastic elastomer. 2. The method according to claim 1, wherein the thermoplastic elastomer is a styrene-based thermoplastic elastomer.
2. The sheet-like key top according to claim 1, wherein the key top is selected from vinyl chloride, olefin, polyester, polyamide and urethane.