Switch having a ball member

A switch comprising:

• a housing;
• an emitter including an emitter main body disposed in said housing, and an emitter head to emit a light signal;
• a receiver including a receiver main body disposed in said housing, and a receiver head to receive the light signal;
• a receptacle disposed in said housing, and including a first wall proximate to said emitter and having a light exit hole aligned with said emitter head, a second wall proximate to said receiver, and a tubular wall connected between said first and second walls, said first and second walls and said tubular wall defining a chamber having a tapered portion that gradually converges from said tubular wall toward said light exit hole, said first wall and said tubular wall being formed integrally, said second wall being a plate that is formed separately from said tubular wall, said second wall having a projection projecting into said chamber from an inner surface of said second wall, said plate of said second wall having an annular protrusion surrounding said projection and abutting against an inner surface of said tubular wall, and a light entry hole that extends through said second wall and said projection, said emitter head, said light exit hole, said light entry hole, and said receiver head being aligned with each other along a light path;
• and
• a ball member rollable within said chamber, and in certain positions of the switch the projection controls the ball movement with respect to the light path.