JPH02111897U - - Google Patents

Description

[Brief explanation of the drawing]

1 to 1c are circuit diagrams of the photoelectric smoke detector according to claim 1, FIG. 2 is a timing chart showing its operation, and FIG. 3 is a circuit diagram of the photoelectric smoke detector according to claim 2. FIG. 4 is a circuit diagram showing the structure inside the chamber of the smoke detector, FIG. 5 is a circuit diagram of a conventional photoelectric smoke detector, and FIG. 6 is a timing chart showing its operation. Explanation of symbols, 1...first constant voltage circuit, 2...
Second constant voltage circuit, 3...Light emitting element drive circuit, 3
a...Light emitting element, 4...Light receiving signal amplification circuit, 4a
... Light receiving element, 5 ... Signal processing circuit, 6 ... First
a trigger circuit, 7...a second trigger circuit, SC
R1...first switching element, SCR2...
Second switching element, TC1...first charge/discharge circuit, TC2...second charge/discharge circuit, V1...
First reference voltage, V2... second reference voltage.

Claims (1)

[Claims for Utility Model Registration] (1) A light-emitting element drive circuit that causes a light-emitting element to emit light intermittently, and a light-receiving element that detects light scattered by smoke from the emitted light pulses from this light-emitting element, and output level corresponding to smoke density. a light reception signal amplification circuit for amplifying and outputting the electric signal of the light reception signal amplification circuit; a signal processing circuit for processing the electric signal of the light reception signal amplification circuit by a synchronization pulse synchronized with the drive pulse of the light emitting element drive circuit; a first trigger circuit having a first charge/discharge circuit charged by a signal from the signal processing circuit and a first reference voltage; and a second charge/discharge circuit charged by a signal from the signal processing circuit. and a second trigger circuit having a second reference voltage; and a first switching element that is driven by the trigger signal of the first trigger circuit to short-circuit the first signal line and the common line. , a second switching element that is driven by the trigger signal of the second trigger circuit to short-circuit the second signal line and the common line; and a switching element between the first signal line and the common line. The first step is to stabilize the supply voltage to a predetermined voltage level.
a constant voltage circuit, and a second constant voltage that stabilizes the supply voltage between the second signal line and the common line to a predetermined voltage level lower than the output voltage of the first constant voltage circuit. In the photoelectric smoke detector, the signal processing circuit outputs an output signal from the light reception signal amplification circuit to the first and second trigger circuits when the synchronization pulse is input, and The first charging/discharging circuit of the trigger circuit is
While being charged with a predetermined charging time constant by the output signal of the signal processing circuit, during the period when the output signal of the signal processing circuit is stopped, it is discharged with a predetermined discharging time constant that is longer than the charging time constant. and a second charging/discharging circuit of the second trigger circuit,
While being charged by the output signal of the signal processing circuit with a predetermined charging time constant that is longer than the charging time constant of the first charging/discharging circuit, during the period when the output signal of the signal processing circuit is stopped, A photoelectric smoke detector, characterized in that the photoelectric smoke detector is configured to discharge at a predetermined discharge time constant that is longer than the discharge time constant of the first charging/discharging circuit. (2) A light-emitting element drive circuit that causes the light-emitting element to emit light intermittently; and a light-receiving element that detects light scattered by smoke from the emitted light pulses from the light-emitting element using a light-receiving element, and amplifies and outputs an electrical signal with an output level that corresponds to the smoke density. a signal amplification circuit; a signal processing circuit that processes the electric signal of the light reception signal amplification circuit by a synchronization pulse synchronized with the drive pulse of the light emitting element drive circuit; and a signal processing circuit that is charged by the signal from the signal processing circuit. a trigger circuit having a charge/discharge circuit and a reference voltage; a switching element that is driven by a trigger signal of the trigger circuit to short-circuit the signal line and the common line; and a switching element between the signal line and the common line. In a photoelectric smoke detector equipped with a constant voltage circuit that stabilizes a supply voltage to a predetermined voltage level, the signal processing circuit transmits an output signal from the light reception signal amplification circuit to the trigger circuit when the synchronization pulse is input. The charging/discharging circuit of the trigger circuit is charged with a predetermined charging time constant by the output signal of the signal processing circuit, while the period when the output signal of the signal processing circuit is stopped is a predetermined charging time constant. A photoelectric smoke detector characterized in that it discharges with a discharge time constant of . (3) The signal processing circuit according to claim 1 or 2, characterized in that the signal processing circuit includes a compensation circuit that compensates for a delay in the output signal from the light reception signal amplification circuit when the synchronization pulse is input. photoelectric smoke detector.