Dome-Shaped Contact and Multi-Step Operation Electrical Switch Incorporating the Same

A multi-step operation electrical switch having a contact formed on a board and a dome-shaped elastic conductive plate, comprising:

• a first dome portion;
• a first spacer portion that is disposed along the outer periphery of said first dome portion;
• a second dome portion that is disposed at the center of said first dome portion with a second spacer portion interposed between the first and second dome portions;
• a first contact that faces the first dome portion;
• and
• a second contact that faces the second dome portion,
• wherein said first dome portion and said second dome portion bulge in the same direction,
• said first and second spacer portions are both conical and tapered in said bulge direction, and
• the radius of curvature of said second dome portion is smaller than the radius of curvature of said first dome portion.

A multi-step operation electrical switch having a contact formed on a board and a dome-shaped elastic conductive plate, said elastic plate being deformed to come into electrical contact with said contact when the elastic plate is pressed, and said elastic plate being restored to the initial shape and electrically disconnected from said contact when a pressing force is removed, the multi-step operation electrical switch comprising:

• a first dome portion that is a part of said elastic plate, bulges in the direction opposite to the direction in which the elastic plate is pressed, and is depressed by a pressing force applied thereto;
• a first contact that is formed on the board and comes into contact with said first dome portion when the first dome portion is depressed;
• a first spacer portion that is a part of said elastic plate and serves to maintain a clearance between the first dome portion and the first contact when said first dome portion is not depressed;
• a second dome portion that is a part of said elastic plate, bulges in the direction opposite to the direction in which the elastic plate is pressed, and is depressed by a pressing force that is greater than the pressing force applied to depress said first dome portion;
• a second contact that is formed on the board and comes into contact with said second dome portion when the second dome portion is depressed;
• and
• a second spacer portion that is a part of said elastic plate and serves to maintain a clearance between the second dome portion and the second contact when said first dome portion is depressed but said second dome portion is not depressed.