Variable frequency light pulser for smoke detectors

Details Variable frequency light pulser for smoke detectors Variable frequency light pulser for smoke detectors

1977-06-20

1979-08-07

Caldwell, Sr., John W.

Communications: electrical

Condition responsive indicating system

Specific condition

250574, G08B 1710, G01N 2126

Patent

active

041639693

ABSTRACT:
A scatter type of battery smoke detector includes a clock circuit applying energy pulses to an LED light source which directs light pulses on a smoke sensing path. Smoke entering the light path scatters pulsed light to a photodiode whose output voltage varies with smoke density and corresponding light pulse level. A threshold stage responds to photodiode voltage above a threshold level to generate a detection pulse. The detection pulses and clock pulses are applied to a control circuit including a dual data-type flip-flop logic circuit, and thence to a threshold circuit driving an alarm horn. If the smoke density and hence the detection pulse amplitude exceed a predetermined level, coincident application of the clock and detection pulses to the control circuit will cause the control circuit to respond by energizing the alarm continuously so long as the detection pulses recur at the clock frequency. If a spurious noise voltage should coincide with a clock pulse the control circuit will energize the alarm, but only for the brief inter-pulse interval. To reduce battery drain the inter-pulse is made relatively long by design of the normal clock circuit time constant. But, to reduce the time that a spurious alarm can sound, the clock circuit time constant is shortened substantially when the control circuit responds to coincident pulses.

REFERENCES:
patent: 4068130 (1978-01-01), Malinowski

Affiliated with

Also associated with

Rating

Variable frequency light pulser for smoke detectors does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Variable frequency light pulser for smoke detectors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Variable frequency light pulser for smoke detectors will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1526840