Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1994-04-19
1996-11-19
Hofsass, Jeffery
Communications: electrical
Condition responsive indicating system
Specific condition
340693, 250574, 356336, 356438, G08B 17107
Patent
active
055766978
ABSTRACT:
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.
REFERENCES:
patent: 3901602 (1975-08-01), Gravatt, Jr.
patent: 4679939 (1987-07-01), Curry et al.
patent: 4999512 (1991-03-01), Zito
patent: 5104221 (1992-04-01), Bott et al.
patent: 5280272 (1994-01-01), Nagashima et al.
Aizawa Masato
Nagashima Tetsuya
Hochiki Kabushiki Kaisha
Hofsass Jeffery
Wu Daniel J.
LandOfFree
Fire alarm system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fire alarm system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fire alarm system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-543682