Shin-etsu Polymer Co., Ltd.

Kenichi Okada

Ryoichi Sado

Yoshitsugu Morikawa

Kiyoshi Nomoto

A key-board switching unit for electronic instruments is constructed with a printed circuit board provided with a plural number of pairs of fixed contact points on the surface and an insulating covering sheet member mounted on or above the printed circuit board and provided on the bottom surface with movable contact points to face the fixed contact points. Different from conventional units in which exact correspondence in the positions of the fixed and movable contact points is required with time- and labor-consuming assembling works, the movable contact points in multiple numbers distributed over the whole bottom surface of the covering sheet member in such a manner that, when the covering sheet member is pushed and depressed at the switching position, the fixed contact points forming a pair of the counter-electrodes are contacted and electrically connected with at least one movable contact point even without exact positioning of the covering sheet member and the printed circuit board to give a great advantage of the increased productivity in the works of assembling. In particular, the movable contact points are formed of a pressure-sensitive electroconductive rubber.

Keyboard switch assembly

The invention provides a novel composition capable of giving an electrically conductive, flexible shaped body having stability in the applied voltage vs. current performance. The composition comprises an electrically insulating polymeric material having flexibility such as a diorganopolysiloxane, a finely divided particulate or fibrous metallic silicon such as a finely powdered semiconductor grade high purity metallic silicon dispersed in the insulating polymeric material as the matrix and an organosilicon compound having at least one functional group directly bonded to the silicon atom or at least one peroxy linkage directly bonded to the silicon atom in a molecule.

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Ageo, Japan

Kenichi Okada