FIRE DETECTOR UTILIZING ULTRAVIOLET AND INFRARED SENSORS

• US 3,665,440 A
• Filed: 08/19/1969
• Issued: 05/23/1972
• Est. Priority Date: 08/19/1969
• Status: Expired due to Term

• Current Assignee: James M. Mcmenamin
• Original Assignee: James M. Mcmenamin
• Inventors: McMenamin, James M.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Wannisky, William M.
• Application Number:
  US04/851,221
• Time in Patent Office: 1,008 Days
• Field of Search: 340/228,228.2,227,224 250/83.3H,83.3UV,237R,237P,237S 317/133.5
• US Class Current: 340/578
• CPC Class Codes: F23N 2229/08 detecting flame flicker
• CPC Class Codes: F23N 2229/14 using two or more different types of flame sensor
• CPC Class Codes: G08B 17/12 Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions

Abstract

A fire detector consisting principally of a first radiation detector for detecting radiation in the infrared region of the spectrum and a second detector for detecting radiation in the ultraviolet region of the spectrum, connected to an alarm through a logic circuit. The logic circuit is adapted to set-off the alarm only if the infrared detector detects infrared radiation at a predetermined level in the flicker frequency range of a flame for a predetermined period of time in the absence of ultraviolet radiation at such flicker frequency detected by the ultraviolet detector.

Claims

1. A fire detector comprising a first radiation detection means for providing a first signal in a first channel as a function of radiation detected substantially in the infrared region of the spectrum, first filter means in said first channel for passing said first signal within a predetermined flicker frequency range, said flicker frequency range being about 5 to 20 cycles per second, threshold means in said first channel for providing an output signal as a result of a signal of a predetermined amplitude at the output of said first filter means, second radiation detection means in a second channel for providing a second signal as a function of radiation detected substantially in the ultraviolet region of the spectrum, second filter means in said second channel for passing said second signal within said predetermined flicker frequency range, gating means normally inhibited by the presence of said second signal in said second channel, means for applying said first signal in said first channel to said gating means, integrating means responsive to said first signal of a predetermined duration of at least 5 seconds appearing at the output of said gating means, and alarm means actuated by said integrating means.

2. The fire detector of claim 1, further comprising a radio link between said integrating means and said alarm means.

3. The fire detector of claim 2, further comprising encoder and decoder means in said radio link.

4. A fire detector comprising a first channel consisting of a first radiation detector for converting radiation emitted by a flame substantially in the infrared region of the spectrum to a first electrical signal, band pass first amplifier means for amplifying said first electrical signal within a predetermined flicker frequency range and for rejecting said first electrical signal outside of said frequency range and threshold circuit means for passing said amplified first electrical signal above a predetermined amplitude, and a second channel consisting of a second radiation detector for converting radiation substantially in the ultraviolet region of the spectrum to a second electrical signal and band pass second amplifier means for amplifying said second electrical signal within said predetermined flicker frequency range and for rejecting said electrical signal outside of said frequency range, said fire detector further comprising inhibit circuit means adapted to pass said first amplified electrical signal in said first channel only in the absence of said second amplified electrical signal in said second channel, integrating circuit means for providing an output signal in the event of an Electrical signal of a predetermined duration appearing at the output of said inhibit circuit means, and alarm means actuated by said output signal.

5. The fire detector of claim 4, wherein said first and second band pass amplifier means are tuned to the same frequency range.

6. The fire detector of claim 5, wherein said frequency range is about 5 to 20 cycles per second.

7. The fire detector of claim 4, wherein the duration of said signal at the output of said inhibit circuit means is at least 5 seconds.

8. The fire detector of claim 4, further comprising encoder means at the output of said integrating circuit means for encoding said output signal, radio transmitter means for transmitting said encoded output signal, radio receiver means for receiving said encoded output signal, and decoder means for decoding said output signal, whereby said alarm means is actuated by said decoded output signal.