Sensor control apparatus and gas detection system
AssigneeNgk Spark Plug Co., Ltd.
InventorsYuzo Higuchi, Tomonori Uemura
Life of this patent
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Abstract
A sensor control apparatus (2) of a gas detection system (1) includes a first low-pass filter (46), a second low-pass filter (48), and a multiplexer (50) so as to provide different time constants for detection of a sensor output signal Vs1 and for detection of a response signal Vs2. When the sensor output signal Vs1 is detected, a signal whose frequency band is the same as that of Vs1 is input to the analog-to-digital conversion section (31) through the first low-pass filter (46). Therefore, the detection accuracy of Vs1 is increased. When Vs2 is detected, a signal whose frequency band is the same as that of Vs2 is input to the analog-to-digital conversion section (31) through the second low-pass filter (48).
Claims6
A sensor control apparatus for controlling a gas sensor including a sensor element which outputs a sensor output signal, the sensor output signal changing with a change in the concentration of a gas and which includes a first cell composed of a solid electrolyte body and a pair of electrodes,
- the sensor control apparatus comprising:
- a detection signal generation section which generates an impedance detection signal for detecting the impedance of the first cell;
- an analog-to-digital conversion section which receives the sensor output signal, the sensor output signal changing with a change in the concentration of the gas, or which receives a response signal generated by the first cell in response to the impedance detection signal, and which converts the analog value of the sensor output signal or the response signal to a digital value, the sensor output signal and the response signal being output from the first cell;
- and
- a time-constant variable filter section which is a low-pass filter provided in a signal path between the first cell and the analog-to-digital conversion section and having a variable time constant,
- the time-constant variable filter section having a time constant which changes such that the time constant at the time when the sensor output signal is input to the analog-to-digital conversion section is greater than the time constant at the time when the response signal is input to the analog-to-digital conversion section.
Dependencies are inferred from the claim text.