Patent ID: 7345552

Claim:
A constant temperature type crystal oscillator comprising: a heat supply body that supplies heat to a crystal resonator from which a plurality of lead wires are led out, to maintain the temperature constant; an oscillating element that constitutes an oscillating circuit together with said crystal resonator; a temperature control element that constitutes a temperature control circuit for controlling the temperature of said crystal resonator; and a circuit board for mounting said heat supply body, said oscillating element, and said temperature control element, and through which lead wires of said crystal resonator are passed through the mounting, wherein said heat supply body comprises: a heat conducting plate which has through holes for said lead wires and is mounted on said circuit board, and which faces, and is directly thermally joined to, said crystal resonator; and a chip resistor for heating which is mounted on said circuit board adjacent to said heat conducting plate, and is thermally joined to said heat conducting plate, wherein said heat conducting plate has first concavities on a first pair of opposite end sides, and said chip resistors that have been thermally joined to said heat conducting plate are disposed inside said first concavities, wherein said concavities extend through the entire heat conducting plate in the direction of said through holes.