Fast warm-up oven controlled piezoelectric oscillator

Claim 1

An oven controlled oscillator assembly comprising an evacuated ceramic flatpack crystal enclosure, a piezoelectric crystal plate within said crystal enclosure, a piezoelectric crystal plate within said crystal enclosure, thermally insulating means mounting said crystal plate in said crystal enclosure, said crystal enclosure having at least one lid which includes an infrared transmitting window, an infrared source in close proximity to said window outside of said crystal enclosure to emit radiation through the window to said crystal plate, a reflector mounted as a dome over said window with said infrared source between the window and the reflector, said radiation being of wavelengths absorable by said crystal plate, means including temperature sensing means on said crystal plate and temperature control circuitry for controlling the emission from the infrared source so as to maintain said crystal plate at a predetermined temperature, oscillator circuitry and means for thermally insulating said crystal plate and oscillator circuitry from the environment outside said assembly, whereby the assembly has a very small thermal time constant for fast warmup of the crystal plate, and a very large thermal time constant to give insensitivity to outside environmental changes.