Ear thermometer and measuring apparatus used with it

A measuring apparatus for an ear thermometer comprising:

• a common voltage line;
• a built-in battery serving as a power source;
• a connector to receive a connector of a probe, having a common voltage terminal connected to the common voltage line;
• a flash-type microcontroller to control a temperature sensor of the probe, receive a resistance value output signal corresponding to a measured temperature from the temperature sensor, convert the signal into a digital temperature value, and output the digital temperature value, the microcontroller having a test port, a program write port, and a common voltage port connected to the common voltage line, establishing a flash mode when a HIGH voltage higher than a first predetermined voltage is applied to the test port, to enable a program to be written through the write port, and establishing a run mode when a LOW voltage lower than the first predetermined voltage is applied to the test port;
• a voltage regulator having an input side connected to the common voltage line, to provide a constant reference voltage;
• and
• a mode switching circuit connected to the common voltage line, to apply the HIGH voltage to the test port of the microcontroller when a common voltage is higher than a second predetermined voltage, apply the LOW voltage to the test port of the microcontroller when the common voltage is lower than the second predetermined voltage, and bypass a leakage current passing from the common voltage line to the mode switching circuit toward an output of the voltage regulator so as to combine them together,
• the connector having the common voltage terminal, a battery power source terminal connected to the built-in battery, a program write terminal connected to the write port of the microcontroller, and a sensor connection terminal to receive the resistance value output signal corresponding to a measured temperature from the temperature sensor of the probe.