Patent US3820097A successfully refreshed from Google Patents.
US3820097A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flame detection system with compensation for the flame detector
Assignee: Honeywell Inc
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Filing: 1973-04-16
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Granted: 1974-06-25
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Expires: 1993-04-16
Abstract
Abstract A flame detection system utilizes a flame responsive impedance, such as a lead sulphide photocell, and responds to the change in infrared radiation and the flame flicker frequency of the sensed flame. The flame responsive impedance is connected through a variable impedance means to a source of direct current voltage. The voltage between the flame responsive impedance and the variable impedance means is compared by an amplifier to a voltage divider network so that a feedback voltage can be generated by the amplifier to control the variable impedance means. The variable impedance means is controlled by the feedback so as to keep the direct current voltage across the flame responsive impedance constant to compensate for variations in flame background radiation, and cell to cell variation. The system then uses a band-pass amplifier and detector-integrator system to control an output switch.
Inventors
- 👤 M Larson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:01
CPC Classifications
F; F23; F23N; F23N5/00; F23N5/02; F23N5/08; F23N5/082; F23N2223/00; F23N2223/20; F23N2229/00; F23N2229/08; F23N2229/16
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
138 words
A flame detection system with direct current source means adapted to be connected to flame responsive impedance means which changes impedance when exposed to radiation from a flame, including: variable impedance means adapted to connect said flame responsive impedance means to said direct current source means; voltage reference means; amplifier means having input means and output means including feedback means with said input means connected between said flame responsive impedance means and said voltage reference means; said feedback means connected to control said variable impedance means by providing said variable impedance means with a direct current feedback voltage to stabilize a direct current potential across said flame responsive impedance means; and said output means further being connected to switch means to control said switch means in response to radiation of a flame at said flame responsive impedance means.
Claim 2
Dependent Claim
138 words
A flame detection system with direct current source means adapted to be connected to flame responsive impedance means which changes impedance when exposed to radiation from a flame, including: variable impedance means adapted to connect said flame responsive impedance means to said direct current source means; voltage reference means; amplifier means having input means and output means including feedback means with said input means connected between said flame responsive impedance means and said voltage reference means; said feedback means connected to control said variable impedance means by providing said variable impedance means with a direct current feedback voltage to stabilize a direct current potential across said flame responsive impedance means; and said output means further being connected to switch means to control said switch means in response to radiation of a flame at said flame responsive impedance means.
Claim 3
Dependent Claim
39 words
A flame detection system as described in claim 1 wherein said variable impedance means, said flame responsive impedance means, and said voltage reference means form a bridge with said amplifier means input connected to an output of said bridge.
Claim 4
Dependent Claim
20 words
A flame detection system as described in claim 2 wherein said flame responsive impedance means is an infrared flame detector.
Claim 5
Dependent Claim
36 words
A flame detection system as described in claim 3 wherein said variable impedance means includes transistor means in series circuit with said flame detector; said transistor means being connected to said feedback means and controlled thereby.
Claim 6
Dependent Claim
17 words
A flame detection system as described in claim 4 wherein said switch means includes second amplifier means.
Claim 7
Dependent Claim
34 words
A flame detection system as described in claim 5 wherein said second amplifier means is a band-pass amplifier means responsive to pass a frequency in the frequency range of the flicker of a flame.
Claim 8
Dependent Claim
28 words
A flame detection system as described in claim 6 wherein said second amplifier means further includes clipper means to limit the voltage input to said second amplifier means.
Claim 9
Dependent Claim
52 words
A flame detection system as described in claim 7 wherein said second amplifier means also includes output means having detector and integrator circuit means responsive to said flame flicker frequency so that said detector and integrator circuit means is activated by a sequence of flame flicker signals received by said flame detector.
Claim 10
Dependent Claim
36 words
A flame detection system as described in claim 4 wherein said transistor means includes a first transistor controlled by said feedback means; and a second transistor in series circuit with said first transistor and slaved thereto.
Claim 11
Dependent Claim
57 words
A flame detection system as described in claim 1 wherein said variable impedance means is radiation responsive impedance means and radiation source means with said radiation responsive impedance means varying in impedance with changes in radiation from said radiation source means; and said feedback means connected to control a radiation level generated by said radiation source means.
Claim 12
Dependent Claim
35 words
A flame detection system as described in claim 10 wherein said radiation responsive means is a photoresistor and said radiation source means is a light source with said resistor and light source in a package.
Claim 13
Dependent Claim
17 words
A flame detection system as described in claim 10 wherein said switcH means includes second amplifier means.
Claim 14
Dependent Claim
34 words
A flame detection system as described in claim 12 wherein said second amplifier means is a band-pass amplifier means responsive to pass a frequency in the frequency range of the flicker of a flame.
Claim 15
Dependent Claim
28 words
A flame detection system as described in claim 13 wherein said second amplifier means further includes clipper means to limit the voltage input to said second amplifier means.
Claim 16
Dependent Claim
52 words
A flame detection system as described in claim 14 wherein said second amplifier means also includes output means having detector and integrator circuit means responsive to said flame flicker frequency so that said detector and integrator circuit means is activated by a sequence of flame flicker signals received by said flame detector.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |