Hochiki Kabushiki Kaisha

Masato Aizawa

Tetsuya Nagashima

Hiroshi Shima

Hidenari Matsukuma

A fire detection device comprises a detection element to convert the infrared ray energy into the electric signal, a first extracting unit to extract the signal of a first prescribed frequency range including the flicker frequency of a fire from the output signal of the detection element, a second extracting unit to extract the signal of a second prescribed frequency range including no flicker frequency of a fire but including the frequency on the higher frequency side than that of the first prescribed frequency range from the output signal of the detection element, and a judging unit to judge a fire based on the output signal of the first extracting unit and the output signal of the second extracting unit. The fire detection device is capable of surely discriminating and detecting the flame from other infrared ray energy generation source. A band pass filter or the like need not be increased in number, and the increase in the product price can be prevented. In particular, the flame detection device is capable of rapidly judging a fire, and suitable for practical applications.

Flame detection device and flame detection

A fire alarm system comprises a first light emitting device (11), a first polarizing filter (31), a first light receiving device (21), a second light emitting device (12), a second polarizing filter (32), and a second light receiving device (22). With the above arrangement, the amount of the parallel polarized component to the scattering plane as well as the amount of the perpendicular polarized component to the scattering plane is detected. The ratio between these amounts of light has a correlation with the type of smoke. A calculation section (4) calculates this ratio from the outputs of the light receiving devices (21, 22). A decision section (6) compares the above-described ratio with a reference value which has been preset according to the type of smoke to be detected, whereby the judgement of whether there is a fire or not is performed depending on the type of smoke. Thus, the detection of a fire can be performed from the light scattered by smoke taking into account the type of smoke.

Fire alarm system

A fire alarm system which radiates light towards a smoke detecting space. Scattered light resulting from smoke that may exist in the smoke detecting space is judged by a receiver with respect to the type of smoke that may prevail in the space. The presence of a fire is judged by comparing the light that has been received with a set threshold level. The threshold level is set to different levels in accordance with the type of smoke detected.

Growing community of inventors

Hachiouji, Japan

Masato Aizawa