Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1993-05-19
1995-03-21
Hofsass, Jeffery A.
Communications: electrical
Condition responsive indicating system
Specific condition
250384, G08B 1710
Patent
active
054000130
ABSTRACT:
An ionization type smoke detector includes a smoke detecting section including an intermediate electrode and an outer electrode to confine an outer ionization chamber therebetween into which smoke to be detected is introduced, and a reference resistance section for forming a reference resistance with respect to the outer ionization chamber, and a sensor output section including a first transistor with its gate connected to the intermediate electrode, and a serial circuit connected to a source of the first transistor and consisting of a first fixed resistor and a first constant-current circuit having a first variable resistor for output adjustment, the sensor output section producing a sensor output from a junction between the first constant current circuit and the first fixed resistor; a fire discriminating section including a reference voltage generating circuit having a second variable resistor for reference voltage adjustment, the fire discriminating section producing a discrimination output when the sensor output exceeds a reference voltage; and fire signal transmitting section for transmitting a fire signal in response to the discrimination output. The sensitivity is easily adjusted and a current flowing during fire monitoring is not changed with different supply voltages.
REFERENCES:
patent: 3866195 (1975-02-01), Ried, Jr.
patent: 4081795 (1978-03-01), Ogawa
patent: 4091363 (1978-05-01), Siegel et al.
patent: 4097850 (1978-06-01), Conforti
patent: 4193069 (1980-03-01), Cooper et al.
patent: 4364031 (1982-12-01), Scheidweiler et al.
patent: 4524351 (1985-06-01), Kimura et al.
patent: 4825196 (1989-04-01), Morita
patent: 5189399 (1993-02-01), Beyersdorf
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