Keyboard arrangement having after-control signal detecting sensor in electronic musical instrument

Claim 1

A keyboard arrangement in an electronic musical instrument, comprising: a plurality of keys pivotably supported and arranged in juxtaposed relationship, said keys being manually movable toward and away from a sensor means, and an after-control signal detecting sensor means positioned at a distance from said keys and extending in transverse direction of the direction of movement thereof keys to correspond to all of these keys, said sensor means comprising a flexible conductive pressure transmitting member serving as a first electrode member facing the bottoms of said keys at said distance therefrom, a conductive base member serving as a second electrode member, and a conductive flexible and elastic member extending below a number of said keys, with said first and second electrode members embedded therein at positions close to opposite surfaces of said elastic member, said conductive flexible and elastic member being made of a flexible and elastic material containing conductive particles dispersed therein and exhibiting a difference in electrical resistance between the state in which this member is compressed and deformed and the state in which it is not compressed and deformed, said first electrode member being adapted to flex itself when pressed by at least one of said keys to transmit to the conductive flexible and elastic member the pressures received from said at least one key of the keyboard to cause compression and deformation of the conductive flexible and elastic member in proportion to the magnitude and amount of said pressure thereby varying its resistance, said two electrode members being connected to input terminals of an electric circuitry of said instrument to input said varying resistance as an after-control signal.