Temperature measuring system
First Claim
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1. A temperature measurement system comprising:
- a capacitance-resistance oscillator circuit having a time constant circuit including at least one thermistor functioning as a resistive element, for producing an output signal at a frequency which varies with ambient temperature in a manner determined by a temperature coefficient of said thermistor;
control circuit means coupled to receive said oscillator circuit output signal, and responsive thereto for periodically producing groups of pulses, with the number of pulses in each of said groups varying in a manner determined by the value of said oscillator circuit output signal frequency during generation of said group; and
a logarithmic transformation circuit coupled to receive said groups of pulses from said control circuit means, and responsive to each of successive ones of said groups for producing digital data representing a numeral which is the logarithm of the number of pulses in said group, whereby said digital data varies in accordance with ambient temperature in a substantially linear manner within a limited range of temperatures.
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Abstract
A temperature measuring system which includes a CR oscillator circuit and a logarithmic transformation circuit. The CR oscillator circuit employs at least a thermistor as the resistance element for forming a time constant with a capacitor which serves as the capacitance element, the oscillation frequency of the oscillator circuit varying with a change in ambient temperature. The logarithmic transformation circuit subjects the information obtained from the CR oscillator circuit to a logarithmic transformation, whereby said information is logarithmically compressed to provide numerical data approximately dependent upon ambient temperature.
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Citations
9 Claims
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1. A temperature measurement system comprising:
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a capacitance-resistance oscillator circuit having a time constant circuit including at least one thermistor functioning as a resistive element, for producing an output signal at a frequency which varies with ambient temperature in a manner determined by a temperature coefficient of said thermistor; control circuit means coupled to receive said oscillator circuit output signal, and responsive thereto for periodically producing groups of pulses, with the number of pulses in each of said groups varying in a manner determined by the value of said oscillator circuit output signal frequency during generation of said group; and a logarithmic transformation circuit coupled to receive said groups of pulses from said control circuit means, and responsive to each of successive ones of said groups for producing digital data representing a numeral which is the logarithm of the number of pulses in said group, whereby said digital data varies in accordance with ambient temperature in a substantially linear manner within a limited range of temperatures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification