Push button switch including complementary housing and actuator polygonal shapes

A push button switch, comprising:

• a key cap having a bottom surface and a plunger extending vertically from the bottom surface, the plunger having a side surface and a bottom surface, a hook being provided near a bottom end of the side surface;
• a housing having a vertical slot with an opening for the passage and reciprocal movement of the plunger guided by an inner surface of the housing, the inner surface defining a polygon shape with an internal obtuse angle at each of a plurality of intersecting corners thereof along a horizontal cross section;
• an elastically deformable actuation means received within the housing, the actuation means being deformed in response to the reciprocal movement of the plunger;
• a membrane switch, in response to a status of the actuation means, for on-off control of an electric equipment;
• said push button switch being characterized in that the side surface of the plunger defines a complementary polygon shape with an internal obtuse angle at each of a plurality of intersecting corners thereof along the horizontal cross section such that a plurality of line contacts between the side surface of the plunger and the inner surface of the housing are provided, thereby reducing operation resistance of the push button switch.