Fire detector
AssigneeNittan Company, Limited
InventorTetsuo Kimura
Life of this patent
Estimating the term…
Abstract
In a fire detector that includes a sensor for producing an output voltage corresponding to smoke concentration, temperature, etc., there is provided a charge-and-discharge circuit to be reset by the turning ON of a switching circuit which is made ON at a fixed voltage. The output of the charge-and-discharge circuit and the output of a sensor are applied to the switching circuit to vary the ON period of the switching circuit corresponding to the output voltage of the sensor. Any irregularity in the sensor can be monitored by changes in the ON period.
Claims9
A fire detector designed for connection between a pair of electrical alarm lines, comprising:
- a sensor producing an output voltage which corresponds to a magnitude of a condition of interest, such as smoke concentration, air temperature and the like;
- a charge reservoir connected between said pair of alarm lines and being charged by current flowing through them;
- and
- a switching circuit connected to the sensor and the charge reservoir and turning on and off to respectively discharge and charge the charge reservoir, the switching circuit turning on as a function of said output voltage and voltage across the charge reservoir, whereby the charge reservoir is repeatedly charged and discharged with a period determined by said output voltage.
A fire detector designed for connection between a pair of electrical alarm lines, comprising:
- a sensor producing an output voltage which corresponds to a magnitude of a condition of interest, such as smoke concentration, air temperature and the like;
- a charge reservoir connected between said pair of alarm lines and being charged by current flowing through them;
- a switching circuit connected to the sensor and the charge reservoir and turning on and off to respectively discharge and charge the charge reservoir, the switching circuit turning on as a function of said output voltage and voltage across the charge reservoir;
- and
- means for determining how long the switching circuit is on and off.
Dependencies are inferred from the claim text.