Claims
- 1. In a fire-responsive control device of the type including a fire detector which produces a trigger signal when a change of surrounding physical phenomenon is caused by fire, a control circuit responsive to said detector, a controlled apparatus, and a DC source, the improvement in said detector comprising an output stage including a thyristor arranged to receive the trigger signal to turn on the thyristor when the detector responds to said change, said thyristor being connected in parallel with said control circuit through a pair of DC source-signal lines so as to include the switching path of said thyristor in a current path including said DC source, said control circuit comprising means for detecting a current flowing through said current path when said thyristor is turned on, an oscillator connected in parallel with said thyristor so as to begin oscillating operation when said means detects said current, first relay means arranged to periodically turn off said thyristor by an oscillating output of the oscillator, second relay means arranged to energize said controlled apparatus when said means detects said current, and delay means connected to maintain the operation of said second relay means for a predetermined interval after transient suppression of said current in said thyristor from the DC source, said controlled apparatus being connected with said control circuit so as to be energized by said second relay means while said second relay means is in operation.
- 2. The control device according to claim 1 wherein said means for detecting the current is connected in series with said thyristor, and wherein said oscillator and said second relay means are connected across the DC source in a parallel combination when said means detects the current flowing through said current path.
- 3. The control device according to claim 2 wherein said means for detecting the current comprises a first relay connected in series with said thyristor and a normally open contact of said first relay, said contact being arranged to connect said oscillator and second relay means across the DC source on the source side of said first relay when said means detects the current flowing through said current path.
- 4. The control device according to claim 2 wherein said means for detecting the current comprises a first resistor connected in series with said thyristor and first transistor connected to be turned on by the voltage drop across said resistor so as to connect said oscillator across the DC source through said first transistor when said first transistor is turned on, a second transistor connected to be turned on by said first transistor through said delay means when said first transistor is turned on, said second relay means being connected across the DC source through said second transistor.
- 5. The control device according to claim 3 wherein said first relay means comprises a second relay having a normally closed circuit and a normally open contact which are connected in a first series combination, a resistor connected between said means for detecting the current and said thyristor so as to form a second series combination with said thyristor, and a capacitor connected between the junction of said normally closed contact and said normally open contact of said second relay and the junction of said resistor and the anode electrode of said thyristor, said first series combination being connected in parallel with said second series combination so as to form a discharge circuit including said normally open contact of said second relay said first capacitor and said thyristor when said normally open contact of said second relay is closed.
- 6. The control device according to claim 4 wherein said first relay means comprises a third transistor which is connected in series with said means for detecting the current and said thyristor across the DC source, said third transistor being connected to periodically turn off by the oscillating output of said oscillator so as to transitorily suppress the current flowing through said thyristor from the DC source.
- 7. The control device according to claim 2 wherein said second relay means is connected across the DC source and energized through said delay means by said means for detecting the current when said means detects the current flowing through said current path.
- 8. The control device according to claim 4 wherein said delay means comprises a series circuit of a diode and a capacitor which is connected across the DC source when said means detects the current flowing through said current path, and a second resistor connected in series between a base electrode of said second transistor and the junction of said diode and said capacitor, whereby said diode is forward-biased when said means detects the current flowing through said current path and said capacitor is charged by a current flowing through said diode from the DC source so that after the suppression of current flowing through said current path, the energization of said second transistor is continued until said capacitor has discharged through said second resistor.
BACKGROUND OF THE INVENTION
The present application is a continuation-in-part of the parent application Ser. No. 810,004 filed June 24, 1977, now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
3286185 |
Gilbert |
Nov 1966 |
|
3299288 |
McDowell et al. |
Jan 1967 |
|
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
810004 |
Jun 1977 |
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