Flame detector using a light guide for optical sensing

Patent metadata

Field	Value
Publication number	US-9251683-B2
Application number	US-201113235057-A
Country	US
Kind code	B2
Filing date	Sep 16, 2011
Priority date	Sep 16, 2011
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

A multi-sensor fire detector includes first and second flame sensors which are coupled to an external environment by a rigid, tapered, optical coupling element. An external end of the coupling element has a cured hemispherical shape with a viewing angle approaching one hundred eighty degrees. Processing and control circuits coupled to the sensors make a determination as to the presence of a fire condition.

First claim

The invention claimed is:

1. A detector comprising multiple optical flame sensor assemblies that operate simultaneously comprising:
a one-piece, elongated, rigid light guide having a hemispherical optical input end where light from a flame directly enters the light guide anywhere over the hemispherical optical input end, a tapered body, and an optical output end,
wherein the light guide comprises first and second different, optical flame sensor assemblies, each comprised of a distinct optical bandpass filter and a photodiode for dual frequency temperature evaluation of the light from the flame where each sensor assembly responds to an optical, flame related, signal of a respective color frequency of a flame having an orange-yellowish color and light intensity changes at frequencies below 20-30 Hz; and
control circuits, responsive to at least outputs from the different sensor assemblies, wherein the control circuits form a ratio of signals from the first and second sensor assemblies to detect the presence of flames of a fire.

2. The detector as in claim 1 where the frequencies comprise first and second different frequencies.

3. The detector as in claim 1 where the input end receives input radiant energy over a viewing angle in excess of one hundred seventy degrees.

4. The detector as in claim 1 where the input end is symmetrical about an elongated axis which extends through the output end.

5. The detector as in claim 1 which includes first and second signal processing circuits coupled to respective sensor assemblies and to the control circuits and where the sensor assemblies comprise radiant energy responsive semiconductors.

6. The detector as in claim 1 wherein the first and second optical band pass filters are positioned between the output end and the photodiodes.

7. The detector as in claim 6 where the filters each exhibit a center frequency with the frequencies offset from one another, and where the filters are symmetrically located on each side of an elongated axis which extends through the light guide and through the output end.

8. The detector as in claim 7 which includes at least one added sensor, different from the first and second sensor assemblies.

9. The detector as in claim 8 where the added sensor is selected from a class which includes at least smoke, gas, thermal, and humidity sensors.

10. The detector as in claim 9 which includes a housing that has at least an optical input and ambient condition input ports.

11. The detector as in claim 10 where the control circuits evaluate ambient temperatures indicated by signals from the first and second sensor assemblies.

12. The detector as in claim 1 where the control circuits each include a selected low pass filter.

13. The detector as in claim 10 where the light guide extends between a portion of the housing and the first and second sensor assemblies.

Assignees

• Petrovic Dragan
• Honeywell Int Inc

Inventors

• Petrovic Dragan

Classifications

• G08B29/043

  of fire detection circuits · CPC title

• G01J5/0014

  for sensing the radiation from gases, flames · CPC title

• G08B17/10

  Actuation by presence of smoke or gases {, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means} · CPC title

• G08B17/12 Primary

  Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions · CPC title

• G08B29/183

  Single detectors using dual technologies (G08B13/1672, G08B13/2448, G08B13/2494 take precedence) · CPC title