Method and apparatus for calibration of comfort control IR sensor
First Claim
1. In a comfort control system having a thermal sensor including an IR sensor having an output responsive to interior vehicle radiant temperatures relative to the thermal sensor temperature and a thermistor circuit having an output responsive to the temperature of the thermal sensor, and a microprocessor based control receiving outputs of the IR sensor and the thermistor circuit to determine a value proportionate to the interior vehicle radiant temperature as the sum of the thermistor circuit output and a gain times the IR sensor output, the method of compensating for errors in the IR sensor signal comprising the steps of:
- stabilizing the interior vehicle temperature;
detecting the sensor output values;
then heating the temperature sensor;
then again detecting the sensor output values; and
compensating for any error by adjusting the value of the gain in the microprocessor based control.
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Accused Products
Abstract
An infrared sensor for determining the temperature of a car interior includes a thermistor and a thermopile in a can and a protective window which exposes the thermopile to the thermal energy of the car interior. The combined outputs of these thermally sensitive elements represents the interior radiant temperature. The effectiveness of the thermopile changes if the window gets dirty to change its output. A resistive heater on the can is used to heat the sensor during calibration. A microprocessor receiving the outputs of the sensor has an algorithm for adjusting a gain which compensates for sensor changes. When the interior temperature is stable, the sensor is heated and thermistor values before and after heating the sensor are used as a basis for adjustment of the gain.
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Citations
11 Claims
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1. In a comfort control system having a thermal sensor including an IR sensor having an output responsive to interior vehicle radiant temperatures relative to the thermal sensor temperature and a thermistor circuit having an output responsive to the temperature of the thermal sensor, and a microprocessor based control receiving outputs of the IR sensor and the thermistor circuit to determine a value proportionate to the interior vehicle radiant temperature as the sum of the thermistor circuit output and a gain times the IR sensor output, the method of compensating for errors in the IR sensor signal comprising the steps of:
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stabilizing the interior vehicle temperature; detecting the sensor output values; then heating the temperature sensor; then again detecting the sensor output values; and compensating for any error by adjusting the value of the gain in the microprocessor based control. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A comfort control system for supplying regulated air to the passenger compartment of an automotive vehicle having temperature sensor calibration comprising:
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a sensor package including an IR sensor responsive to thermal radiation levels in the compartment relative to the sensor temperature, a thermistor responsive to the temperature of the sensor package, and a heater for heating the package, the IR sensor being subject to change in efficiency; a controller including a microprocessor coupled to the sensor package for regulating the temperature, mode and air speed of air entering the passenger compartment; a circuit including the microprocessor combining outputs of the IR sensor and the thermistor to produce a thermal value representing the interior vehicle temperature; and the controller including means for turning on the heater for a given time when the thermopile temperature is equal to the interior radiant temperature, means for storing a calibration value which compensates for IR sensor changes, and means for adjusting the calibration value to neutralize any apparent change of the thermal value upon heating. - View Dependent Claims (11)
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Specification