円形平板状水晶振動子の小形化に伴う周波数温度特性と変曲点温度の検討 Frequency-Temperature Behavior and Inflection Temperature of Miniaturized Circular Disk AT-Cut Crystal Resonator
In the field of watch industry, the requirement of the practical application of miniaturized AT-cut crystal resonator, of which f requency temperature behavior is cubic curve, has increased in accordance with the development of miniature electronic components in MHz. The ratio of diameter to thickness of the conventional circular disk AT-cut plate is usually more than l5, but the ratio of miniaturized one described in this paper is ranged from 4.338 to 4.683 (diameter: from 6.329 mm to 6.832 mm, thickness: 1.459 mm, resonance frequency: about l.2 MHz). The vibration mode of the miniaturized circulardisk AT-cut crystal resonator is composed of coupling between the thickness shear and the flexure. The coupling modulus g, containing both the thickness shear modulus and the flexure modulus, is discussed. The relation between the g and the cut angle from minor face ( r' face ) is calculated, and the cut angles examined in this paper are decided by the minimum part of g variation. The frequency temperature behaviors are measured, every time the diameter of specimen is gradually decreased by polishing by a few micron meter. It is understood by these measurements that the resonance frequency is not almost changed in the wide temperature range ( e. g. -l0℃〜40℃) by the selection of both the cut angle and the ratio of diameter to thickness. The first, the second, and the third temperature coefficients are varied with the ratio of diameter to thickness. The relations between the temperature coefficient Tf and the temperature accompanied with each ratio are examined. And also the inflection temperatures are calculated by mentioned above coefficients. It is shown that the inflection temperature depends on the cut angle and the ratio of diameter to thickness. The polishing accuracy of the specimen is studied by experimental results.
日本時計学会誌 (95), 2-25, 1980-12-10