Patent ID: 8431852

Claim:
A key switch device comprising: a switch panel; a key top positioned above the switch panel; a pair of link members positioned between the key top and the switch panel and adapted to support the key top so that the key top may be moved in a vertical direction while maintaining a horizontal posture; a membrane sheet positioned below the switch panel and adapted to close and open a contact of an electric circuit corresponding to the vertical motion of the key top; an actuating member positioned between the membrane sheet and the key top and adapted to close the contact corresponding to the downward motion of the key top; and an annular elastic wall member positioned between the switch panel and the membrane sheet, wherein the elastic wall member is formed on an upper side of the membrane sheet so as to be arranged along a contour of the key top, and is configured to contact a surface of the switch panel, the surface opposing the upper side of the membrane sheet.