US3836857A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flame detector
Assignee: Hitachi Ltd
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Filing: 1973-04-24
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Granted: 1974-09-17
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Expires: 1993-04-24
Abstract
Abstract A flame detector wherein a pair of diodes are connected in series with opposite directions of conduction across the respective terminals of an AC power source, and a light emitting device, such as a discharge tube, is connected between the point of connection of the two diodes and a flame rod disposed in a flame to be detected. With this construction, a predetermined voltage is applied between a burner and the flame rod, whichever side of the AC power source is grounded.
Inventors
- 👤 K Ikegami
- 👤 M Yamamoto
- 👤 J Honda
- 👤 M Miyanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:09
CPC Classifications
F; F23; F23N; F23N5/00; F23N5/02; F23N5/12; F23N5/123
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
150 words
A flame detector comprising a grounded burner, a flame rod disposed at a place at which a flame from the burner is to exist, first and second non-linear impedance means each presenting a low impedance when a voltage is applied thereto and exhibiting a high impedance when no voltage is applied thereo, an AC power source having one of its terminals grounded, one of said terminals of said power source being connected to one terminal of said first non-linear impedance means and the other terminal thereof being connected to one terminal of said second non-linear impedance means, and a light emitting device for emitting light in response to the presence to the flame, one of the electrodes of said light emitting device being connected to said flame rod and the other electrode being connected in common to the other terminal of each of saiD first and second non-linear impedance means.
Claim 2
Dependent Claim
150 words
A flame detector comprising a grounded burner, a flame rod disposed at a place at which a flame from the burner is to exist, first and second non-linear impedance means each presenting a low impedance when a voltage is applied thereto and exhibiting a high impedance when no voltage is applied thereo, an AC power source having one of its terminals grounded, one of said terminals of said power source being connected to one terminal of said first non-linear impedance means and the other terminal thereof being connected to one terminal of said second non-linear impedance means, and a light emitting device for emitting light in response to the presence to the flame, one of the electrodes of said light emitting device being connected to said flame rod and the other electrode being connected in common to the other terminal of each of saiD first and second non-linear impedance means.
Claim 3
Dependent Claim
20 words
The flame detector according to claim 1, wherein each of said first and second non-linear impedance means comprises a diode.
Claim 4
Dependent Claim
83 words
The flame detector according to claim 1, wherein each of said first and second non-linear impedance means comprises a non-linear photoconductive element having a high resistance when not irradiated by light and presenting a low resistance when irradiated by light, and a light emitting element formed integrally therewith, said light emitting element being connected between one terminal of said AC power source and ground, said photoconductive element being connected between said one terminal of said AC power source and said light emitting device.
Claim 5
Dependent Claim
25 words
The flame detector according to claim 3, wherein a capacitor for bypassing AC signal components is connected across the terminals of said light emitting device.
Claim 6
Dependent Claim
96 words
A flame detector comprising a grounded burner, first and second flame rods disposed at a place at which a flame from the burner is to exist, an AC power source one of its terminals grounded, and first and second light emitting devices for emitting light in response to the presence of the flame, said first light emitting device being connected between said first flame rod and one of the terminals of said AC power source, said second light emitting device being connected between said second flame rod and the other terminal of said AC power source.
Claim 7
Dependent Claim
96 words
A flame detector comprising a grounded burner, first and second flame rods disposed at a place at which a flame from the burner is to exist, an AC power source one of its terminals grounded, and first and second light emitting devices for emitting light in response to the presence of the flame, said first light emitting device being connected between said first flame rod and one of the terminals of said AC power source, said second light emitting device being connected between said second flame rod and the other terminal of said AC power source.
Claim 8
Dependent Claim
30 words
The flame detector according to claim 5, wherein an individual capacitor for bypassing AC signal components is connected across both terminals of, and in parallel with, each light emitting device.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-16 | 1978-03-18 | 1978-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-16 | 1982-03-18 | 1982-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-16 | 1986-03-18 | 1986-09-17 | $7700.00 | Window Closed / Lapsed |