Ebauches S.a.

Rudolf J Dinger

The invention relates to a piezo-electric crystal reasonator comprising a tuning fork having two tines, one on each side of an axis of symmetry, having in addition to the excitation electrodes formed on the tines, auxiliary electrodes comprising conductive coatings formed, with the same axis of symmetry, on the same crystal which interconnects the two tines and further relates to a method for making such tuning fork resonator including the detection of asymmetry by applying an excitation voltage to the excitation electrodes to cause the resonator to oscillate, and while it is oscillating, detecting a voltage appearing between the auxiliary electrodes to indicate asymmetrical oscillation of the tines. In addition to excitation electrodes (5, 6, 7) on the tines (2, 3) of the tuning fork, auxiliary conductive electrodes (17, 18, 19, 21) are formed on a part of the resonator which interconnects the two tines. The resonator is then caused to oscillate by applying an excitation voltage to said excitation electrodes and, while it is oscillating, the voltage appearing between the auxiliary electrodes in the event of an asymmetrical oscillation of the tines is detected. Any asymmetry between the two tines can thus be detected and corrected in the course of the manufacture of the tuning fork.

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St.-Aubin, Switzerland

Rudolf J Dinger