Key switch having jointed links

1. A key-switch, comprising:

a keycap configured to be pressed down;

a base member; and

a link mechanism disposed between the keycap and the base member and configured to support the keycap such that the keycap is movable up and down relative to the base member,

wherein the link mechanism includes four links arranged in a rectangular shape, and each of the links includes a sliding part configured to slide on the base member, a mounting part attached to the keycap, and joints connecting adjacent links among the four links together.

2. The key-switch as claimed in claim 1 , wherein the joints include a convex part formed at one end of the mounting part and a concave part formed at another end of the mounting part, the concave part of one of the links being configured to engage rotatably with the convex part of another one of the links.

3. The key-switch as claimed in claim 1 , further comprising a membrane switch having a rubber actuator disposed thereon, wherein the base member has an opening through which the rubber actuator passes through, and the rubber actuator situated in the opening is in contact with the keycap.

4. The key-switch as claimed in claim 1 , further comprising an electrical switch formed on the base member, and is turned on and off in response to sliding movement of the sliding part.

5. The key-switch as claimed in claim 1 , wherein the four links are attached to the keycap through the respective mounting parts of the four links such that the four links are movable relative to the keycap around four pivot axes, respectively, the four pivot axes being arranged in a rectangular shape.

6. The key-switch as claimed in claim 1 , wherein the joints are configured such that movement of a given one of the four links mechanically causes movement of two links immediately adjacent to the given one of the four links.