Patent ID: 8085105

Claim:
A constant-temperature type crystal oscillator comprising: a crystal unit comprising: a case main body comprising first mounting terminals for surface mounting including a first power source terminal on an outer bottom surface of the case main body; and a crystal element that is hermetically encapsulated in the case main body; a surface-mounted oscillator, which comprises an IC chip housed in the case main body, and which forms an oscillator circuit with at least the crystal unit; a temperature control circuit comprising: a heating resistor composed of a chip element for heating up the crystal unit; and a temperature sensor that detects an operational temperature of the crystal unit; and a circuit substrate, on which the surface-mounted oscillator, the heating resistor, and the temperature sensor are installed, and which comprises second mounting terminals including a second power source terminal, wherein one end of the heating resistor and one end of the temperature sensor are electrically connected to the second power source terminal, wherein the first power source terminal of the surface-mounted oscillator and the one end of the heating resistor and one end of the temperature sensor are electrically connected to the second power source terminal of the circuit substrate, and wherein the first power source terminal of the surface-mounted oscillator is directly and electrically connected to, at least, the one end of the temperature sensor via an electrically-conducting path.