Patent ID: 7312414

Claim:
A key switch device comprising: a support plate; a key top arranged above the support plate; a pair of link members interlocked to each other to support the key top above the support plate and direct the key top in a vertical direction; and a switch mechanism capable of opening and closing a contact section of an electric circuit in accordance with a vertical movement of the key top, wherein each of the pair of link members has a toothed end such that the link members are assembled together into a reverse V-shape as seen in a lateral direction, and a sliding part is slidably engaged with the support plate, wherein the switch mechanism includes a membrane switch sheet carrying the contact section at a position corresponding to the key top and placed on the support plate, wherein the support plate has a displacement restricting part arranged on the support plate, wherein each of the pair of link members has an engaging part configured to contact the displacement restricting part at any time during the vertical movement of the key top, whereby the displacement of the key top in the sliding direction of the sliding part of each of the pair of link members is restricted, and wherein each of the pair of link members has two arm portions and a body portion coupling the two arm portions, and the engaging part includes a curved concave portion and a curved convex portion formed on the body portion.