Nittan Company Limited

Lixil Nittan Company, Limited

Akihisa Kudoh

Hiroshi Kaneko

Kazuyoshi Sakurai

Nobuyuki Akiyama

Masahiro Katagiri

A flame detector is provided. A circuit board is disposed in a housing. A first light source emits first light. A light guide member comprised of translucent material guides the first light from the first light source to a light emission portion of the light guide member. A first light receiving element detects second light having a predetermined wavelength unique to the flames. A second light source emits third light to a translucent cover which is disposed between an opening of the housing and the first light receiving element. A second light receiving element detects the third light passed through the translucent cover to test the translucency. The first light source, the second light source and the second light receiving element are mounted on the circuit board. The light emission portion is formed into a substantially annular shape which encloses the first light receiving element at a front side of the housing to limit a field of view of the first light receiving element to a predetermined range. And 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.

Flame detector

Fire detector

A first band pass filter selects and transmits light having an infrared wavelength specific to flame. A first infrared-ray receiving element receives the light from the first band pass filter. A second band pass filter selects and transmits light having an infrared wavelength which is not the infrared wavelength specific to flame. A second infrared-ray receiving element receives the light from the second band pass filter. A first output of the first infrared-ray receiving element is compared with a second output of the second infrared-ray receiving element to detect the flame. When light having homogeneous energy in a transmissive wavelength band of the first band pass filter and a transmissive wavelength band of the second band pass filter is incident on the first band pass filter and the second band pass filter, an amount of the light transmitted through the second band pass filter is less than an amount of the light transmitted through the first band pass filter, and the first output and the second output are adjusted so that a level of the first output is equal to a level of the second output.

Growing community of inventors

Tokyo, Japan

Akihisa Kudoh