Abstract: A key switch comprises a first link member 12 and a second link member 13, and the first link member 12 has a pair of legs 12a, 12b, linked with each other by a first connection bar 12c as well as a second connection bar 12d. The legs 12a, 12b are provided with pivots 12e, 12f, respectively, and the second link member 13 is attached to the external side of the first link member 12, rotatably about the pivots 12e, 12f, respectively. The back surface of a key top 11 is provided with a pair of rotation supports 11a, 11b, and a pair of slide supports 11c, 11d. The former serving for rotatably supporting one end of the first link member 12, and the latter for slidably supporting one end of the second link member 13. An elastic member 14 is disposed inside the first link member 12, and causes electrical connection to be made between contacts 16a, and 16b when the key top 11 is pressed down.

Abstract: A keyboard unit having a base plate, and a plurality of key switches provided on the base plate. Each of the key switches has an electric contact provided within a membrane sheet on the base plate, an elastic dome portion formed on the base plate so as to cover the electric contact, a bearing portion provided on base plate, and a key cap having a support shaft which engages the bearing portion, and an engaging portion which engages the dome portion. When the key cap is depressed, the dome portion is elastically deformed so that an inner surface of the dome portion presses against the electric contact, and when the key cap is not depressed, deformation of the dome portion is removed so that the inner surface of the dome portion is separated from the electric contact and the key cap is pushed up by the dome portion.