Linearized digital thermometer

An electronic thermometer, comprising:

• a thermistor having a predetermined non-linear temperature and resistance relationship characteristic;
• a source operatively connected for directing a constant current through the thermistor to thereby create an analog voltage across said thermistor related to thermistor temperature by the predetermined temperature and resistance relationship;
• visual display means operatively connected in said electronic thermometer for visually displaying an indication of a calculated equivalent temperature as sensed by said thermistor;
• converter means operatively connected for receiving the analog voltage across said thermistor and for supplying a digital signal directly related to the analog voltage;
• computer means operatively connected for controlling said converter means to supply the digital signal, for calculating an equivalent temperature from the digital signal applied from said converter means, and for operatively controlling said display means to display a visual indication of the calculated equivalent temperature;
• said computer means including a solid state preprogrammed read only memory containing information in a lookup table defining a predetermined piecewise linearized approximation of the predetermined non-linear temperature and resistance characteristic of said thermistor, the information in said lookup table including slope and constant information for each segment of the piecewise linearized approximation;
• said computer means calculating the equivalent temperature for each individual digital signal supplied by said converter means by relating each digital signal from said converter means to the piecewise linearized approximation recorded in the lookup table, by obtaining slope and constant information for each digital output signal from said lookup table, and by digitally performing a first order algebraic calculation with each digital signal and with the slope and constant information obtained for that digital signal, the result of the calculation being the equivalent temperature;
• and
• said computer means conducting a signal representative of the equivalent temperature to said display means and controlling said display means to visually display an indication of the equivalent temperature.