Patent ID: 7426338

Claim:
A switch mechanism usable underwater comprising: an exterior member having a first hole and a second hole; a first pressing operation member being watertight against the first hole of the exterior member; a second pressing operation member being watertight against the second hole of the exterior member; first switch means being turned on/off by the first pressing operation member; second switch means being turned on/off by the second pressing operation member; and a lever member being rotatable around a fulcrum being provided in the exterior member, pressing the first pressing operation member at a first contact point when rotating in a first direction, and pressing the second operation member at a second contact point when rotating in a second direction opposite to the first direction, wherein, when a cross-sectional area at a boundary of water and air in a state of the first pressing operation member being inserted into the first hole is defined as S 1 , and a cross-sectional area at a boundary of water and air in a state of the second pressing operation member being inserted into the second hole is defined as S 2 , and wherein, when a distance between the fulcrum and the first contact point is defined as R 1 , and a distance between the fulcrum and the second contact point is defined as R 2 , and wherein, when static frictional force occurring when the first pressing operation member is forced into the first hole is defined as F 1 , and static frictional force occurring when the second pressing operation member is forced into the second hole is defined as F 2 , and wherein, when the water pressure is defined as P, the lever member has a rotational balance of the water pressure when the following mathematical formula is satisfied: P×S 1× R 1+ F 1× R 1= P×S 2× R 2+ F 2× R 2.