Abstract: A linking mechanism used in a key switch assembly is disclosed to include a first link, which is shaped like an open frame, and a second link, which is receivable within the first link. The first link and the second link are respectively symmetrically configured and obliquely coupled between a key cap and a positioning plate above a circuit module in a crossed manner for performing a scissor action to guide vertical movement of the key cap relative to the circuit module for enabling the key cap to be pressed by a user to trigger the circuit module in producing a control signal.

Abstract: A self-illumination circuit board includes a double-layer substrate structure, a circuit layer embedded in the substrate structure and carrying a circuit layout, side-emitting light sources mounted in the substrate structure and electrically connected to the circuit layout for emitting light sideways, and light guide plates embedded in the substrate structure and respectively disposed adjacent to the side-emitting light sources for uniformly distributing light emitted from the side-emitting light sources over respective light exit surfaces thereof. The invention also provides a self-illumination keyboard using the self-illumination circuit board.