Apparatus for controlling ventilation fan
AssigneeMatsushita Seiko Co., Ltd.
InventorMasahiko Kawasaki
Life of this patent
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Abstract
The level of a signal voltage of a sensor circuit 9 which changes depending upon the environmental change is detected by comparing the signal voltage with a reference voltage which is constant for a period of time longer than the period of the signal voltage and is momentarily and stepwise changed between a plurality of values. A change in the signal voltage is determined by a determining circuit 14 for operating a ventilation fan. Accurate detection of the environmental change can be made at an improved response even if a power source voltage for the sensor circuit 9 is so unstable or is pulsated that the signal voltage of the sensor circuit 9 has a changing amplitude.
Claims2
A device for controlling a ventilation fan, comprising:
- a sensor circuit for generating a signal voltage having an amplitude which oscillates at a predetermined period and changes depending upon an environmental change;
- means for detecting the signal voltage by comparing the signal voltage from said sensor circuit with a reference voltage which is constant for a period of time longer than the predetermined period of the signal voltage and is momentarily and stepwise changed to assume a plurality of values;
- and
- means for controlling the operation of a ventilation fan depending upon a change in the signal voltage which is detected by said detecting means.
A device for controlling a ventilation fan, comprising:
- a sensor circuit for generating a signal voltage having an amplitude which oscillates at a predetermined period and changes depending upon an environmental change;
- means for detecting the signal voltage by comparing the signal voltage from said sensor circuit with a reference voltage which is constant for a period of time longer than the predetermined period of the signal voltage and is momentarily and stepwise changed to assume a plurality of values by means of a combination of a plurality of resistors, the resistances of which increase by step of double as high as one resistor, and
- means for controlling the operation of a ventilation fan depending upon a change in the signal voltage which is detected by said detecting means.
Dependencies are inferred from the claim text.