Abstract: A plurality of arcuate grouping contacts and a plurality of strip contacts are formed in an annular array in opposed spaced relation with each other on two insulation layers. A control key is disposed in opposed position to the annular array of contacts on the side of one of the insulation layers opposite from the other of the layers, and an annular elastic member is interposed between the undersurface of the control key and the annular array of contacts whereby a portion of one of the insulation layers is displaced toward the other of the insulation layers depending upon the direction and magnitude of a force applied to the control key to bring the grouping contacts corresponding to the direction of the force into contact with one or more of the strip contacts.

Abstract: A membrane switch sheet is disposed on a base plate and an adhesive layer is formed all over the membrane switch sheet. A positioning sheet, which has positioning holes respectively corresponding to membrane switches arranged on the membrane switch sheet, is disposed on the adhesive layer, and a tact plate having a normally upward curved portion is bonded to the adhesive layer in each positioning hole. A mounting plate is disposed on the positioning sheet at a distance therefrom. The mounting plate has a sleeve at a position corresponding to each tact plate. A stem is slidably received in the sleeve. The stem is capped with a key top formed integrally therewith. An acutating coiled spring is fixed at one end and engaged at the other end with the tact plate. When the key top is depressed, the coiled spring presses down the corresponding membrane switch through the tact plate, turning on the switch.