| 摘要 |
PURPOSE:To improve the frequency-temperature characteristics of a crystal oscillator, by forming a pierced hole within the main oscillation surface of a crystal oscillator bar which is produced by an etching process. CONSTITUTION:A rectangular pierced hole 4 is formed at about the center in the width direction of the resonance branch 3a of a tuning fork type crystal bar 3 with <=1/3 branch width and with >=1/2 length of the branch 3a from the area near the bottom of a groove 3c in the lengthwise direction. Such hole 4 is drilled by applying a photoethcing process to a crystal ore after forming it into a wafer. The drilled bar 3 has a composite posture of vibration of a flexion vibration and a expansion/contraction vibration within X and Y planes. The arrow 7 shows the degree and direction of the displacement of vibration at a certain moment of vibration. For the cut angle of the bar 3, the zero temperature coefficient TZTC can be set at desired 25 deg.C by turning the Z plate around the axis X by +3 deg.20'. The secondary temperature coefficient is greatly improved with a cut angle of +3 deg.20'. Thus the frequency-temperature characteristics is improved for a crystal oscillator. |
