Abstract: Liquid Crystal compounds represented by the following formula are disclosed. ##STR1## wherein R and R' are independently selected from alkyl groups containing 1.about.20 carbon atoms; X is --O--, --O--CO--O-- or direct bond; A.sub.1 and A.sub.2 are independently cyclic groups (such as phenylene and biphenylene), said cyclic groups may be substituted with 1.about.4 fluorine, chlorine or bromine atoms, or 1 or 2 substituent groups selected from the group consisting of cyano, nitro and trifluoromethyl groups; Y is --CO--O--, --O--CO--, --C.tbd.C--, --CH.sub.2 O--, --OCH.sub.2 --, --CH.dbd.N--, --N.dbd.CH--, --N.dbd.N--, --CH.sub.2 S--, --SCH.sub.2 -- or direct bond; and * represents asymmetric atom providing optical activity.

Abstract: A piezoelectric resonator includes a base plate and a strip-type, energy trapping piezoelectric resonator chip mounted on the base plate. The piezoelectric resonator chip includes a piezoelectric chip plate and a pair of electrode patterns formed on the opposed main surfaces of the piezoelectric chip plate. One main surface of the piezoelectric chip plate faces the base plate and is parallel therewith, and a conductive layer is formed on each end of the main surface facing the base plate. The thickness of the conductive layer is greater than that of the electrode pattern so that the electrode pattern is separated from the base plate. The conductive layer is directly mounted onto a conductive portion of the base plate, so as to electrically connect the electrode pattern and the conductive portion of the base plate.

Abstract: A piezoelectric resonator chip which includes a piezoelectric chip plate and a pair of electrode patterns which is formed on the opposite surfaces of the piezoelectric chip plate, the electrode patterns face each other through the piezoelectric chip plate. At least one of the electrode patterns has an adjuster pattern which includes a narrow cutting pattern and a separation pattern which is connected to the electrode pattern through the cutting pattern and which faces the other electrode pattern.

Abstract: A piezoelectric resonator which resonates in thickness shear mode. The piezoelectric resonator includes a strip shaped resonance chip made of an X-cut plate of lithium tantalate crystal and having a rectangular cross-section. Electrodes are formed at the center portion with respect to the longitudinal direction of the resonance chip on each of two X-plane surfaces. The width of the electrodes is equal to the width of the resonance chip. The longitudinal direction of the resonance chip inclines with respect to the Y-axis by an angle of 50.degree..+-.2' in the clockwise direction in the X-plane so as to make the longitudinal direction of the resonance chip coincide with the displacement direction of primary oscillation of the crystal. Optimal ratios of the dimensions of the resonance chip and terminal connectors at the ends of the resonance chip are given to reduce spurious response.