Abstract: A contact heater arrangement is disclosed for a piezoelectric effect crystal resonator. The piezoelectric effect crystal element may be an SC cut quartz crystal disc having electrodes affixed to one side thereof to generate a lateral field in the crystal disc. The contact heater element is applied to the side of the crystal element opposite the side on which the electrodes are affixed. The particular pattern of the heater leaves the center of the crystal element exposed for frequency adjustment purposes. Locating the heating element and electrodes on opposite sides of the crystal element generates a constant temperature which has been found effective to uniformly heat a piezoelectric effect crystal element, and with appropriate control circuitry, allows for temperature stabilization of the crystal element.

Abstract: SC cut crystal resonators having lateral field excitation are disclosed. An SC cut quartz crystal blank is a doubly rotated Y cut which has the very valuable characteristic that its resonance frequency is stable while under stress, either from temperature gradients or from shock and vibration. Because of the threefold symmetry of quartz, and since the SC cut is rotated 22 degrees about the Z axis, there is a Y axis only about 8 degrees from the surface of an SC cut plate. A lateral field directed along or near this axis strongly excites the C mode and very weakly excites the B mode, if at all. The electrodes generating the lateral field are placed on the same major surface of an SC cut quartz crystal disc element and shaped to place the strongest field in the center of the disc element. This has been found to strongly couple to the C mode and suppress all other modes including the B mode and satellite C modes. Spectral purity and Q are enhanced thereby.