Keyboard having lower casing with integral upraised portion for supporting PC board, and key switch having air vent in PC board

A key switch, comprising:

• a film-like printed-circuit board having a circuit pattern on an upper surface thereof, said circuit pattern including at least one stationary electrode;
• a support plate on which said printed-circuit board rests;
• an elastic sheet resting on said printed-circuit board, and including an elastically collapsible cap portion disposed opposite to said at least one stationary electrode, said cap portion cooperating with said printed-circuit board to define an enclosure in which said at least one stationary electrode is disposed;
• a movable electrode secured to a lower surface of a top wall of said cap portion of said elastic sheet;
• and
• an operator-controlled key operable to press said cap portion at said top wall thereof, thereby causing said cap portion to collapse, so as to move said movable electrode toward said at least one stationary electrode;
• wherein said printed-circuit board has an air vent formed therethrough in communication with said enclosure;
• wherein said support plate has a groove formed in communication with said air vent, so that air in said enclosure may flow into said groove through said air vent when said cap portion collapses upon depression of said key;
• and
• wherein said cap portion has a peripheral wall adjacent to an opening thereof at which said cap portion is closed by said printed-circuit board to form said enclosure, said peripheral wall contacting, upon collapse of said cap portion, the upper surface of said printed-circuit board along a closed loop which is located inside an inner periphery of said cap portion which defines said opening thereof, said air vent being positioned such that at least a part of the air vent is located inside said closed loop of said peripheral wall.

A key switch assembly comprising:

• a film-like printed-circuit board having a circuit pattern on an upper surface thereof, said circuit pattern including a plurality of stationary electrodes;
• a support plate on which said printed-circuit board rests;
• an elastic sheet resting on said printed-circuit board, and including a plurality of elastically collapsible cap portions disposed opposite to said plurality of stationary electrodes, said cap portions cooperating with said printed-circuit board to define a plurality of enclosures in which said plurality of stationary electrodes are disposed;
• a plurality of movable electrodes respectively disposed on lower surfaces of top walls of said cap portions of said elastic sheet;
• and
• a plurality of operator-controlled keys operable to press said cap portions at said top walls thereof, thereby causing said cap portions to collapse so as to move said movable electrodes toward the corresponding stationary electrodes;
• wherein said printed-circuit board has a plurality of air vents formed therethrough, such that each of said plurality of enclosures communicates with at least one of said air vents;
• and
• wherein said support plate has at least one groove formed therein, each of said at least one groove communicating with at least two of said plurality of enclosures through the air vents communicating with said at least two enclosures.