Patent ID: 8201973

Claim:
A flame detector comprising: a housing formed with an opening at a front side thereof; a circuit board disposed in the housing and having a circuit for detecting flames; a first light source mounted on the circuit board and configured to emit first light; a light guide member having a light emission portion, the light guide member comprised of translucent material and configured to guide the first light from the first light source to the light emission portion by internal propagation thereof to emit the first light from the light emission portion ahead of the housing; a first light receiving element configured to detect second light having a predetermined wavelength unique to the flames from the opening; a translucent cover interposed between the opening and the first light receiving element; a second light source configured to emit third light to the translucent cover; and a second light receiving element configured to detect the third light passed through the translucent cover to test the translucency of the translucent cover, wherein the second light source and the second light receiving element are mounted on the circuit board, wherein the light emission portion is formed into a substantially annular shape which encloses the first light receiving element at the front side of the housing to limit a field of view of the first light receiving element to a predetermined range, and wherein the light guide member has a light entrance portion and a light exit portion for the third light to form a light path from the second light source to the second light receiving element through the translucent cover and the light guide member.