Membrane switch, key switch using membrane switch, keyboard having key switches, and personal computer having keyboard

摘要

A membrane switch is constituted of a lower membrane sheet, an upper membrane sheet and a spacer sheet which is inserted between both sheets, and a spring sheet which is formed of a thin metal plate arranged over the upper membrane sheet. A pair of slits formed in the spring sheet at positions corresponding to both sides of an upper electrode of the upper membrane sheet defines a switch portion in the spring sheet. When a key top is pushed down, the switch portion of the spring sheet is pushed down by a pushdown projection of the membrane switch to bring the upper electrode into contact with a lower electrode.