US5162658A
Expired / Lapsed
US
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Thermal detection arrangement having a plurality of optical filter devices
Assignee: Central Research Laboratories Ltd
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Filing: 1991-04-22
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Granted: 1992-11-10
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Expires: 2011-04-22
Abstract
Abstract A thermal detector arrangement includes a number of channels, each including a collimator for collimating incident radiation to a respective optical filter. Each optical filter has a respective radiation passband characteristic with one having a passband spanning the passbands of all of the other optical filters. The radiation passed by each optical filter is passed to a thermal detector, which preferably is in the form of a thermally isolating membrane acting as a radiation absorbent cavity and supported by a semiconductor substrate. The output signals from the thermal detectors are multiplexed, amplified by an amplifier having voltage offset compensation and digitally processed to provide an indication of a fire to be sensed.
Inventors
- 👤 Robert E. Turner
- 👤 Richard A. Ford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:38
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/10; G01J5/12; G01J5/02; G01J5/026; G01J5/08; G01J5/0801; G01J5/0802; G01J5/60; G01J5/602; G08; G08B; G08B17/00; G08B17/12
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
122 words
A thermal detector arrangement comprising a plurality of optical filter devices each having a respective passband characteristic for transmitting radiation having a wavelength indicative of a characteristic of a fire to be detected, a further optical filter device having a passband characteristic spanning the passband characteristics of the plurality of optical filter devices, a plurality of thermal detector devices, each for receiving radiation transmitted by a respective optical filter device and for providing therefrom an output signal indicative of the radiation transmitted by the optical filter device, a multiplexer circuit for multiplexing the output signals from the thermal detector devices, and signal processing means for processing the multiplexed output signals and for providing therefrom an indication of a fire to be detected.
Claim 2
Dependent Claim
122 words
A thermal detector arrangement comprising a plurality of optical filter devices each having a respective passband characteristic for transmitting radiation having a wavelength indicative of a characteristic of a fire to be detected, a further optical filter device having a passband characteristic spanning the passband characteristics of the plurality of optical filter devices, a plurality of thermal detector devices, each for receiving radiation transmitted by a respective optical filter device and for providing therefrom an output signal indicative of the radiation transmitted by the optical filter device, a multiplexer circuit for multiplexing the output signals from the thermal detector devices, and signal processing means for processing the multiplexed output signals and for providing therefrom an indication of a fire to be detected.
Claim 3
Dependent Claim
24 words
A thermal detector according to claim 1 comprising a plurality of collimators for collimating the radiation to be received by the optical filter devices.
Claim 4
Dependent Claim
17 words
A thermal detector according to claim 2 wherein the collimators each comprise a cavity of frustro-conical shape.
Claim 5
Dependent Claim
18 words
A thermal detector according to claim 2 wherein the collimators each comprise a cavity of compound parabolic configuration.
Claim 6
Dependent Claim
58 words
A thermal detector according to claim 1 wherein the thermal detector devices each comprise a silicon substrate having an aperture therein, a thermally isolating membrane supported by the substrate and arranged over the aperture, an absorber supported by the membrane, a hot junction in contact with the absorber and a cold junction in contact with the silicon substrate.
Claim 7
Dependent Claim
58 words
A thermal detector according to claim 2 wherein the thermal detector devices each comprise a silicon substrate having an aperture therein, a thermally isolating membrane supported by the substrate and arranged over the aperture, an absorber supported by the membrance, a hot junction in contact with the absorber and a cold junction in contact with the silicon substrate.
Claim 8
Dependent Claim
63 words
A thermal detector according to claim 1 wherein the thermal detector devices each comprise a silicon substrate having an aperture therein, a thermally isolating membrane supported by thesubstrate, the membrane having a resistive film on one major surface thereof arranged incident to the radiation and a reflector layer on the opposite major surface thereby to provide a radiation absorbent cavity in the membrane.
Claim 9
Dependent Claim
64 words
A thermal detector according to claim 2 wherein the thermal detector devices each comprise a silicon substrate having an aperture therein, a thermally isolating membrane supported by the substrate, the membrane having a resistive film on one major surface thereof arranged incident to the radiation and a reflector layer on the opposite major surface thereby to provide a radiation absorbent cavity in the membrane.
Claim 10
Dependent Claim
13 words
A thermal detector according to claim 7 wherein the reflector layer comprises gold.
Claim 11
Dependent Claim
44 words
A thermal detector according to claim 1 wherein the signal processing means comprises an amplifier circuit for amplifying the multiplexed output signals from the thermal detector devices, the signal processing means including an offset adjust circuit for compensating voltage offset of the amplifier circuit.
Claim 12
Dependent Claim
44 words
A thermal detector according to claim 2 wherein the signal processing means comprises an amplifier circuit for amplifying the multiplexed output signals from the thermal detector devices, the signal processing means including an offset adjust circuit for compensating voltage offset of the amplifier circuit.
Claim 13
Dependent Claim
44 words
A thermal detector according to claim 5 wherein the signal processing means comprises an amplifier circuit for amplifying the multiplexed output signals from the thermal detector devices, the signal processing means including an offset adjust circuit for compensating voltage offset of the amplifier circuit.
Claim 14
Dependent Claim
43 words
A thermal detector according to claim 7 wherein the signal processing means comprises amplifier circuit for amplifying the multiplexed output signals from the thermal detector devices, the signal processing means including an offset adjust circuit for compensating voltage offset of the amplifier circuit.
Claim 15
Dependent Claim
31 words
A thermal detector according to claim 10 wherein the offset adjust circuit comprises an inverting amplifier circuit and an integrating circuit arranged in a feedback loop to the inverting amplifier circuit.
Claim 16
Dependent Claim
31 words
A thermal detector according to claim 13 wherein the offset adjust circuit comprises an inverting amplifier circuit and an integrating circuit arranged in a feedback loop to the inverting amplifier circuit.
Claim 17
Dependent Claim
60 words
A thermal detector according to claim 1 wherein the signal processing means comprises a variable gain amplifier circuit, arranged to receive the output signal from the thermal detector device respective to the further optical filter device, having a gain controlled in dependence upon the level of the output signal from the thermal detector respective to the further optical filter device.
Claim 18
Dependent Claim
60 words
A thermal detector according to claim 7 wherein the signal processing means comprises a variable gain amplifier circuit, arranged to receive the output signal from the thermal detector device respective to the further optical filter device having a gain controlled in dependence upon the level of the output signal from the thermal detector respective to the further optical filter device.
Claim 19
Dependent Claim
60 words
A thermal detector according to claim 10 wherein the signal processing means comprises a variable gain amplifier circuit, arranged to receive the output signal from the thermal detector device respective to the further optical filter device having a gain controlled in dependence upon the level of the output signal from the thermal detector respective to the further optical filter device.
Claim 20
Dependent Claim
24 words
A thermal detector according to claim 1 wherein the signal processing means comprises an analogue to digital converter for digitising the multiplexed output signals.
Claim 21
Dependent Claim
56 words
A thermal detector according to claim 19 comprising processor means for receiving multiplexed digital output signals from the analogue to digital converter and sampling means for sampling the multiplexed digital output signals derived from the output signals of the thermal detector devices a plurality of times for providing the indication of a fire to be detected.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1995-11-10 | 1996-05-11 | 1996-11-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-11-10 | 2000-05-11 | 2000-11-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-11-10 | 2004-05-11 | 2004-11-10 | $7700.00 | Window Closed / Lapsed |