Torsional quartz crystal resonator

A torsional quartz crystal tuning fork resonator, comprising:

• a tuning fork having a plurality of tines vibratable in a torsional mode of vibration during use of the resonator, the tuning fork comprising a quartz crystal Z-cut plate having x, y and z axes corresponding, respectively, to the electrical, mechanical and optical axes of the quartz crystal, the plate having a length defined along the y-axis, a width x.sub.0 defined along the x-axis and a thickness z.sub.0 defined along the z-axis, the fork tines extending lengthwise along the y-axis, and the cut of the plate being defined by rotation of the plate through a first cut angle in the range of 0.degree. through +30.degree. around the x-axis thereby defining new x', y' and z' axes, and rotation of the plate through a second cut angle in the range of -20.degree. through -10.degree. or +10.degree. through +20.degree. around the z' axis to form a quartz crystal tuning fork resonator having a thickness-to-width ratio R.sub.zx =z.sub.0 /x.sub. 0 within the range of 0.6 through 1.1 and having a first order temperature coefficient .alpha. of approximately zero around room temperature.

A torsional quartz crystal tuning fork resonator, comprising:

• a quartz crystal Z-cut plate having x, y and z axes corresponding to the electrical, mechanical and optical axes, respectively, of the quartz crystal, the cut of the plate being defined by rotation of the plate around the x-axis through an angle in the range 0.degree. through +30.degree. thereby defining new x', y' and z' axes and by rotation of the plate around the z'-axis through an angle in the range -20.degree. through -10.degree. or +10.degree. through +20.degree., the plate having a vibrational portion having a tuning fork shape and being vibratable in a torsional mode of vibration, a supporting portion for supporting the resonator, and a bridge portion interconnecting the vibrational and supporting portions such that the vibrational portion can undergo torsional mode vibration relative to the supporting portion during use of the resonator, the resonator having a thickness-to-width ratio R.sub.zx =z.sub.0 /x.sub.0 within the range of 0.6 through 1.1, and the resonator having a first order temperature coefficient .alpha. of approximately zero around room temperature.