| 摘要 |
PURPOSE:To enable the precise detection of a temperature in a wide range, by making the oscillation frequency of an oscillator constant irrespective of a change in the temperature, while making the most of the characteristic of the oscillator in the manner that it has a high temperature resolution without being affected by a suspended capacity and the frequency characteristic of an oscillating element. CONSTITUTION:A temperature detector comprises two C-MOS inverters IV1 and IV2, a temperature-sensitive resistance element determining a time constant together with a capacitor C, e.g. a variable resistor connected in parallel with a thermistor Rth, a resistance array Rx, and a protective resistor Rp. In order to make an oscillation frequency fx constant, it is sufficient that a parallel resistance Rpo has a constant value. Since the resistance value Rth of the thermistor changes with a temperature, the resistance value Rx of the resistance array is made to change with the temperature so as to maintain the oscillation frequency at a constant value. Such operations are performed in several times that the difference between the output frequency of an oscillator 10 and the oscillation frequency fo of a reference oscillator is determined and reduced. A resistance value delivered after these operations satisfy a relational formula for the relation between the temperature and the change in the resistance value of the thermistor. |
