Societe Suisse Pour L'industrie Horlogere Management Services S.a.

Raymond Huguenin

Jean Engdahl

Hubert Matthey

Martial Voumard

Alphonse E Zumsteg

A piezo electric resonator member is cut from a quartz crystal in a rotated -orientation and arranged for vibration in a thickness shear mode, the member being in the form of a bar elongated along either the X-axis or the Z'-axis having rectangular cross sections in planes parallel respectively to the XZ'- and Y'Z'-planes or XZ'- and XY'-planes. It is provided with metallized layers to serve as electrodes confined to a central zone of the surfaces running in the same direction as the XZ'-plane. The ends of the bar serve as support points.

Quartz crystal resonator

This specification describes a rectangular quartz crystal which has been igned with specific length-width-thickness ratios whereby vibration takes place in the thickness shear mode strongly coupled with flexural vibrations. The choice of the specific ratios permits an improved performance insofar as dynamic capacitance range, temperature dependent variations of frequency and finally quality factor are concerned. The dimensions and proportions make the crystal suitable for use as a high frequency time piece resonator.

Quartz piezo-electric element vibrating in a coupled mode

Two frequencies to be compared are applied to two inputs of a flip-flop. output of the flip-flop is fed to a low pass filter and the output of the filter is a saw tooth voltage proportional to the phase difference between the two frequencies. Differentiation of the saw tooth voltage yields a voltage proportional to the difference between the two frequencies. A threshold circuit is provided for sensing the output voltage of the filter to control a flip-flop which in turn reverses the phase of one of the frequency signals and disconnects the output of the differentiator from a capacitive storage circuit.

Frequency comparator

Apparatus for automatically adjusting the frequency of a piezoelectric reator in the form of a bar or plate includes circuitry for applying a voltage to the resonator to cause it to resonate, measuring the frequency of the resonator continuously during a frequency adjusting cycle, continuously comparing the measured frequency with a desired frequency to obtain a difference frequency value, storing the difference frequency value at the beginning of the adjusting cycle, deriving from the difference frequency value a threshold value equal to one-half of the difference frequency value, comparing the threshold value with the frequency difference value, removing material by a sand blast from a first extremity of the resonator as long as the difference frequency value is greater than the threshold value and thereafter removing material from the other extremity of the resonator until the difference frequency value is nil.

Apparatus for automatically adjusting the frequency of piezoelectric

A process for automatically adjusting the frequency of a piezoelectric reator in the form of a bar or plate includes the steps of applying a voltage to the resonator to cause it to resonate, measuring the frequency of the resonator continuously during a frequency adjusting cycle, continuously comparing the measured frequency with a desired frequency to obtain a difference frequency value, storing the difference frequency value at the beginning of the adjusting cycle, deriving from the difference frequency value a threshold value equal to one-half of the difference frequency value, comparing the threshold value with the frequency difference value, removing material by a sand blast from a first extremity of the resonator as long as the difference frequency value is greater than the threshold value and thereafter removing material from the other extremity of the resonator until the difference frequency value is nil.

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Port, Switzerland

Raymond Huguenin