US3906474A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Combustion products alarm
Assignee: FIRE ALERT CO
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Filing: 1973-05-07
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Granted: 1975-09-16
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Expires: 1993-05-07
Abstract
Abstract A combustion products detector of the ionization chamber type comprises a reference ionization chamber and a signal chamber arranged in series for connection across a direct current source such as a dry battery. An insulated gate field effect transistor is arranged with its drain electrode for connection to the high side of the source, and with its source electrode to the law side; its gate is connected to the common junction of the chambers; a high resistance is connected across the chambers in parallel. A control amplifier supplies the signal to a circuit for producing a preliminary alarm or proximity signal upon a predetermined increase in combustion product density in the signal chamber and a full alarm upon an additional increase. The alarm may be produced as a throbbing or undulating sound.
Inventors
- 👤 George S Lehsten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 08:41
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/11
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
368 words
A combustion product detector of the ionization chamber type comprising: a. a reference ionization chamber and a sampling ionization chamber connected in series, b. means including a variable resistor for connecting said chambers in series therewith across circuit terminals for connection to a direct current supply, c. a field effect transistor having source and drain and gate terminals, said gate terminal being connected to the junction between said chambers, and said source and drain terminals being connected across said circuit terminals in series with an output resistance, said field effect transistor being responsive to potential changes across said sampling chamber for providing a signal in proportion thereto, and d. means dependent upon a first predetermined signal at the output of said field effect transistor for indicating the approach of an alarm condition, and e. means dependent upon a second predetermined signal at the output of said field effect transistor for initiating an alarm indication, said means dependent on a first predetermined signal at the output of said field effect transistor further including a light emitting element and an oscillator for repetitively energizing said element beginning upon occurance of the first predetermined signal at the output of said field effect transistor and continuing through attainment of the second predetermined signal at the output of said field effect transistor, said detector further including means dependent upon a predetermined signal at the output of said field effect transistor for utilizing said signal to produce an alarm indication, said signal dependent means including a control amplifier comprising a transistor connected in series with a third resistance across said source and having its base connected to the output of said field effect transistor, and wherein: the oscillator comprises a capacitor connected in series with a portion of said third resistance and said control amplifier across said supply, and a unijunction transistor connected in series with another portion of said third resistance across said first portion and said capacitor and with its emitter connected to the junction of said capacitor and said first portion, and the light emitting source comprises a light emitting diode connected in parallel with at least a portion of said third resistance between said unijunction transistor and said control amplifier.
Claim 2
Dependent Claim
368 words
A combustion product detector of the ionization chamber type comprising: a. a reference ionization chamber and a sampling ionization chamber connected in series, b. means including a variable resistor for connecting said chambers in series therewith across circuit terminals for connection to a direct current supply, c. a field effect transistor having source and drain and gate terminals, said gate terminal being connected to the junction between said chambers, and said source and drain terminals being connected across said circuit terminals in series with an output resistance, said field effect transistor being responsive to potential changes across said sampling chamber for providing a signal in proportion thereto, and d. means dependent upon a first predetermined signal at the output of said field effect transistor for indicating the approach of an alarm condition, and e. means dependent upon a second predetermined signal at the output of said field effect transistor for initiating an alarm indication, said means dependent on a first predetermined signal at the output of said field effect transistor further including a light emitting element and an oscillator for repetitively energizing said element beginning upon occurance of the first predetermined signal at the output of said field effect transistor and continuing through attainment of the second predetermined signal at the output of said field effect transistor, said detector further including means dependent upon a predetermined signal at the output of said field effect transistor for utilizing said signal to produce an alarm indication, said signal dependent means including a control amplifier comprising a transistor connected in series with a third resistance across said source and having its base connected to the output of said field effect transistor, and wherein: the oscillator comprises a capacitor connected in series with a portion of said third resistance and said control amplifier across said supply, and a unijunction transistor connected in series with another portion of said third resistance across said first portion and said capacitor and with its emitter connected to the junction of said capacitor and said first portion, and the light emitting source comprises a light emitting diode connected in parallel with at least a portion of said third resistance between said unijunction transistor and said control amplifier.
Claim 3
Dependent Claim
147 words
In a combustion product detector of the ionization chamber type including a sampling chamber and a reference chamber, means for producing an output signal proportional to the density of combustion product in the sampling chamber, means for producing an amplified voltage proportional to said output signal, and means dependent upon a predetermined amplified voltage for actuating an alarm indicator, the method of calibrating the detector for determination of the density of combustion product in said sampling chamber which comprises: introducing combustion product of a predetermined alarm density in the sampling chamber; ADJUSTING the voltage across the sampling chamber to produce an amplified voltage sufficient to effect actuation of the alarm indicator; and, thereafter, determining the density of combustion product in the sampling chamber as the proportion of the predetermined alarm density in the ratio of the amplified voltage resulting from such product to said alarm actuation voltage.
Claim 4
Dependent Claim
147 words
In a combustion product detector of the ionization chamber type including a sampling chamber and a reference chamber, means for producing an output signal proportional to the density of combustion product in the sampling chamber, means for producing an amplified voltage proportional to said output signal, and means dependent upon a predetermined amplified voltage for actuating an alarm indicator, the method of calibrating the detector for determination of the density of combustion product in said sampling chamber which comprises: introducing combustion product of a predetermined alarm density in the sampling chamber; ADJUSTING the voltage across the sampling chamber to produce an amplified voltage sufficient to effect actuation of the alarm indicator; and, thereafter, determining the density of combustion product in the sampling chamber as the proportion of the predetermined alarm density in the ratio of the amplified voltage resulting from such product to said alarm actuation voltage.
Claim 5
Independent Claim
192 words
The method of calibrating a plurality of like combustion product detectors each of the ionization chamber type including a sampling chamber and a reference chamber, means for producing an output signal proportional to the density of combustion product in the sampling chamber, means for producing an amplified voltage proportional to said output signal and means dependent upon a predetermined amplified voltage for actuating an alarm indicator, comprising the steps of: providing like means for adjusting the voltage across the sampling chamber of each of said detectors; providing means for measuring the amplified voltage on each of said detectors; introducing a density of product to the sampling chamber of one of the detectors, the density being a selected fraction of the alarm density desired, while the one detector is in operation adjusting the voltage across the sampling chamber to provide an amplified voltage equal to the same fraction of the alarm voltage as the selected fraction of the alarm density, and calibrating each of the other detectors of said plurality by setting the respective means for adjusting the voltage across the sampling chamber to the same adjustment as that of said one detector.
Claim 6
Independent Claim
192 words
The method of calibrating a plurality of like combustion product detectors each of the ionization chamber type including a sampling chamber and a reference chamber, means for producing an output signal proportional to the density of combustion product in the sampling chamber, means for producing an amplified voltage proportional to said output signal and means dependent upon a predetermined amplified voltage for actuating an alarm indicator, comprising the steps of: providing like means for adjusting the voltage across the sampling chamber of each of said detectors; providing means for measuring the amplified voltage on each of said detectors; introducing a density of product to the sampling chamber of one of the detectors, the density being a selected fraction of the alarm density desired, while the one detector is in operation adjusting the voltage across the sampling chamber to provide an amplified voltage equal to the same fraction of the alarm voltage as the selected fraction of the alarm density, and calibrating each of the other detectors of said plurality by setting the respective means for adjusting the voltage across the sampling chamber to the same adjustment as that of said one detector.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |