Patent US4647786A successfully refreshed from Google Patents.
US4647786A
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Photoelectric smoke detector and its application
Assignee: OASIS 1563 HUBBARD ST BATAVIA IL 60510
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Filing: 1983-10-10
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Granted: 1987-03-03
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Expires: 2003-10-10
Abstract
Abstract In a photoelectric smoke detector, a radiation source is driven intermittently by a control circuit and the radiation influenced by smoke particles, for instance scattered radiation, is picked up by a radiation receiver. The signal of the radiation receiver is transmitted to a signal processing circuit which is transmitted to a signal processing circuit which is simultaneously regulated by the control circuit. The signal processing circuit comprises a phase sensitive circuit which reverses or inverts the received signal according to the phase of the signal of the control circuit and transmits the thus modified signal to an integrating circuit. The integrating circuit controls a display circuit by means of its integrated output signal. The display circuit can, for instance, output an alarm signal when the integrated signal, i.e. the smoke intensity, exceeds a prescribed threshold value or can display the smoke intensity. In this manner, even weak smoke signals can be surely and reliably detected even when they are fully masked by noise. Such a smoke detector can be advantageously employed as an especially sensitive and interference-resistant fire alarm.
Inventors
- 👤 Hannes Guttinger
- 👤 Martin Labhart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:09
CPC Classifications
G; G08; G08B; G08B29/00; G08B29/18; G08B29/185; G08B17/00; G08B17/10; G08B17/103; G08B17/107; G08B29/20; G08B29/22; G08B17/11; G08B17/113
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
153 words
A photoelectric smoke detector, comprising: a radiation source; a control circuit for generating an alternating driving signal having a phase and serving for intermittently driving said radiation source; a radiation receiver; an evaluation circuit connected to said radiation receiver and capable of outputting an alternating smoke alarm signal when said radiation receiver receives radiation influenced by smoke particles in synchronization with operation of said radiation source; said evaluation circuit comprising a phase sensitive circuit regulated by said control circuit in relation to said intermittent driving of said radiation source and for inverting said alternating smoke alarm signal of said radiation receiver according to said phase of said alternating driving signal of said control circuit for generating an output signal; a display circuit; and an integrating circuit for integrating said output signal of said phase sensitive circuit with a prescribed time-constant and for regulating said display circuit in correspondence with said integrated output signal.
Claim 2
Dependent Claim
153 words
A photoelectric smoke detector, comprising: a radiation source; a control circuit for generating an alternating driving signal having a phase and serving for intermittently driving said radiation source; a radiation receiver; an evaluation circuit connected to said radiation receiver and capable of outputting an alternating smoke alarm signal when said radiation receiver receives radiation influenced by smoke particles in synchronization with operation of said radiation source; said evaluation circuit comprising a phase sensitive circuit regulated by said control circuit in relation to said intermittent driving of said radiation source and for inverting said alternating smoke alarm signal of said radiation receiver according to said phase of said alternating driving signal of said control circuit for generating an output signal; a display circuit; and an integrating circuit for integrating said output signal of said phase sensitive circuit with a prescribed time-constant and for regulating said display circuit in correspondence with said integrated output signal.
Claim 3
Dependent Claim
35 words
The photoelectric smoke detector as defined in claim 1, further including: a frequency filter; and said alternating smoke alarm signal of said radiation receiver being transmitted through said frequency filter to said phase sensitive circuit.
Claim 4
Dependent Claim
36 words
The photoelectric smoke detector as defined in claim 1 further including: a phase shift circuit; and said alternating driving signal of said control circuit being transmitted through said phase shift circuit to said phase sensitive circuit.
Claim 5
Dependent Claim
19 words
The photoelectric smoke detector as defined in claim 1, wherein: said prescribed time-constant of said integrating circuit is variable.
Claim 6
Dependent Claim
49 words
The photoelectric smoke detector as defined in claim 1, wherein: said control circuit comprises means for generating a periodical signal for operating said radiation source and for regulating said phase sensitive circuit; and said periodical signal having active intervals and inactive intervals of essentially the same order of magnitude.
Claim 7
Dependent Claim
44 words
The photoelectric smoke detector as defined in claim 1, wherein: said control circuit comprises means for generating an at least approximately square-wave signal; said at least approximately square-wave signal having an alternating component; and said alternating component being transmitted to said phase sensitive circuit.
Claim 8
Dependent Claim
18 words
The photoelectric smoke detector as defined in claim 6, wherein: said phase sensitive circuit comprises a multiplier circuit.
Claim 9
Dependent Claim
31 words
The photoelectric smoke detector as defined in claim 1, wherein: said display circuit is structured to output a signal as soon as said integrated output signal exceeds a prescribed threshold value.
Claim 10
Dependent Claim
39 words
The photoelectric smoke detector as defined in claim 1, wherein: said radiation receiver is structured and disposed to receive scattered radiation scattered from smoke particles and to emit a signal depending on an intensity of said received scattered radiation.
Claim 11
Dependent Claim
193 words
A photoelectric smoke detector, comprising: a source of radiation for emitting radiation; a control circuit for generating an alternating signal exhibiting a phase and for intermittently driving said source of radiation in synchronism with said phase of said alternating signal; a radiation receiver for receiving a portion of said radiation influenced by smoke particles and for generating an output signal indicative of said received portion and exhibiting a polarity; an evaluation circuit connected to said radiation receiver and to said control circuit for generating a smoke alarm signal when said radiation receiver receives said portion of said radiation influenced by smoke particles in synchronism with said radiation intermittently emitted by said source of radiation; said evaluation circuit comprising a phase-sensitive circuit for receiving both said output signal and said alternating signal and for selectively either preserving said polarity or inverting said polarity according to said phase; means for generating a predeterminate time-constant; an alarm circuit; and said evaluation circuit comprising an integrating circuit connected subsequent to said phase-sensitive circuit for integrating said output signal in relation to said predeterminate time-constant and for controlling said alarm circuit in relation to said integrated output signal.
Claim 12
Dependent Claim
193 words
A photoelectric smoke detector, comprising: a source of radiation for emitting radiation; a control circuit for generating an alternating signal exhibiting a phase and for intermittently driving said source of radiation in synchronism with said phase of said alternating signal; a radiation receiver for receiving a portion of said radiation influenced by smoke particles and for generating an output signal indicative of said received portion and exhibiting a polarity; an evaluation circuit connected to said radiation receiver and to said control circuit for generating a smoke alarm signal when said radiation receiver receives said portion of said radiation influenced by smoke particles in synchronism with said radiation intermittently emitted by said source of radiation; said evaluation circuit comprising a phase-sensitive circuit for receiving both said output signal and said alternating signal and for selectively either preserving said polarity or inverting said polarity according to said phase; means for generating a predeterminate time-constant; an alarm circuit; and said evaluation circuit comprising an integrating circuit connected subsequent to said phase-sensitive circuit for integrating said output signal in relation to said predeterminate time-constant and for controlling said alarm circuit in relation to said integrated output signal.
Claim 13
Dependent Claim
31 words
The photoelectric smoke detector as defined in claim 10, further including: a frequency filter connected between said radiation receiver and said phase-sensitive circuit for transmitting said output signal of said receiver.
Claim 14
Dependent Claim
28 words
The photoelectric smoke detector as defined in claim 10, further including: a phase-shift circuit connected between said control circuit and said phase-sensitive circuit for transmitting said alternating signal.
Claim 15
Dependent Claim
18 words
The photoelectric smoke detector as defined in claim 10, wherein: said predeterminate time-constant is a variably predeterminate time-constant.
Claim 16
Dependent Claim
25 words
The photoelectric smoke detector as defined in claim 10, wherein: said phase of said alternating signal of said control circuit has a symmetrical phase relationship.
Claim 17
Dependent Claim
20 words
The photoelectric smoke detector as defined in claim 10, wherein: said alternating signal is at least approximately a square-wave signal.
Claim 18
Dependent Claim
18 words
The photoelectric smoke detector as defined in claim 10, wherein: said phase sensitive circuit comprises a multiplier circuit.
Claim 19
Dependent Claim
35 words
The photoelectric smoke detector as defined in claim 10, wherein: said alarm circuit comprises means for generating and transmitting an alarm signal in response to said integrated output signal having exceeded a prescribed threshold value.
Claim 20
Dependent Claim
53 words
The photoelectric smoke detector as defined in claim 10, wherein: said radiation receiver is arranged for receiving said portion of said radiation influenced by smoke particles as radiation scattered by smoke particles; and said radiation receiver comprising means for emitting said output signal in dependence of an intensity of said received scattered radiation.
Claim 21
Dependent Claim
211 words
A fire alarm device for detecting smoke particles generated by a fire, comprising: a photoelectric smoke detector; said photoelectric smoke detector comprising: a source of radiation for emitting radiation; a control circuit for generating an alternating signal exhibiting a phase and for intermittently driving said source of radiation in synchronism with said phase of said alternating signal; a radiation receiver for receiving a portion of said radiation influenced by smoke particles and for generating an output signal indicative of said received portion and exhibiting a polarity; an evaluation circuit connected to said radiation receiver and to said control circuit for generating a smoke alarm signal when said radiation receiver receives said portion of said radiation influenced by smoke particles in synchronism with said radiation intermittently emitted by said source of radiation; said evaluation circuit comprising a phase-sensitive circuit for receiving both said output signal and said alternating signal and for selectively either preserving said polarity or inverting said polarity according to said phase; means for generating a predeterminate time-constant; an alarm circuit; and said evaluation circuit comprising an integrating circuit connected subsequent to said phase sensitive circuit for integrating said output signal in relation to said predeterminate time-constant and for controlling said alarm circuit in relation to said integrated output signal.
Claim 22
Dependent Claim
211 words
A fire alarm device for detecting smoke particles generated by a fire, comprising: a photoelectric smoke detector; said photoelectric smoke detector comprising: a source of radiation for emitting radiation; a control circuit for generating an alternating signal exhibiting a phase and for intermittently driving said source of radiation in synchronism with said phase of said alternating signal; a radiation receiver for receiving a portion of said radiation influenced by smoke particles and for generating an output signal indicative of said received portion and exhibiting a polarity; an evaluation circuit connected to said radiation receiver and to said control circuit for generating a smoke alarm signal when said radiation receiver receives said portion of said radiation influenced by smoke particles in synchronism with said radiation intermittently emitted by said source of radiation; said evaluation circuit comprising a phase-sensitive circuit for receiving both said output signal and said alternating signal and for selectively either preserving said polarity or inverting said polarity according to said phase; means for generating a predeterminate time-constant; an alarm circuit; and said evaluation circuit comprising an integrating circuit connected subsequent to said phase sensitive circuit for integrating said output signal in relation to said predeterminate time-constant and for controlling said alarm circuit in relation to said integrated output signal.
References Cited (Backward Citations)
US4206454A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1990-03-02 | 1990-09-01 | 1991-03-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-02 | 1994-09-01 | 1995-03-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-02 | 1998-09-01 | 1999-03-03 | $7700.00 | Window Closed / Lapsed |