Patent ID: 8390390

Claim:
An oven controlled crystal oscillator comprising: a heat-conducting plate mounted on a principal surface of a circuit board; a crystal resonator mounted on a surface of said heat-conducting plate opposite to said surface of the circuit board; an oscillation element constituting an oscillation circuit together with said crystal resonator, and a temperature sensor that detects temperature of said crystal resonator, mounted on said circuit board; a heating resistance mounted on said circuit board, which heats said crystal resonator depending on a temperature detected by said temperature sensor; and a temperature control element including at least a power transistor, mounted on said circuit board to constitute a temperature control circuit together with said temperature sensor and said heating resistance, wherein two or more open areas communicating with said heat-conducting plate at least in the thickness direction thereof are formed on the periphery of said heat-conducting plate at positions mutually symmetric with respect to a center of said crystal resonator, wherein each open area has arranged a said power transistor and a said heating resistance.