Patent ID: 7718910

Claim:
A movable contact assembly comprising: a movable contact having a dome shape having an upper surface and a lower surface, the upper surface of the movable contact being convex, the lower surface of the movable contact being concave, the movable contact having an outer edge; a base sheet made of insulating material, the base sheet including: a dome portion having an upper surface and a lower surface, the lower surface of the dome portion being concave along the upper surface of the movable contact, the lower surface of the dome portion being situated on the upper surface of the movable contact, the dome portion having an outer edge, a flat portion connected with the outer edge of the dome portion and having a lower surface being flat and which is continuous with said lower surface of said dome portion and an upper surface which is continuous with said upper surface of said dome portion; and a board provided on said lower surface of said flat portion of said base sheet without a space therebetween; a columnar portion having an upper surface and a lower surface, the lower surface of the columnar portion being situated on the upper surface of the dome portion away from the outer edge of the dome portion of the base sheet; and a light guide sheet having an upper surface and a lower surface, the lower surface of the light guide sheet contacting the upper surface of the columnar portion, wherein the light guide sheet has a light-receiving surface along an edge of said light guide sheet for introducing light into the light guide sheet, and allows the introduced light to be emitted from the upper surface of the light guide sheet.