Abstract: A piezoelectric transformer comprises a piezoelectric substrate extending in a first direction, a first electrode structure provided on the substrate for exciting an elastic wave propagating through the substrate in the first direction as a result of the piezoelectric transverse effect, and a second electrode structure provided on the substrate for converting the elastic wave to an electric voltage, wherein the first electrode group occupies a first area on the substrate while the second electrode group occupies a second area on the substrate.

Abstract: A piezoelectric transformer comprises a piezoelectric substrate carrying thereon an input electrode structure provided on an upper major surface of the piezoelectric substrate for receiving an a.c. voltage for causing an excitation of an elastic wave in the substrate such that the elastic wave propagates through the substrate in a longitudinal direction, an output electrode structure provided on a lower major surface of the piezoelectric substrate for producing an output a.c. voltage by converting the elastic wave into an electric voltage, wherein the input electrode structure and the output electrode structure have a periodical structure in the longitudinal direction with a pitch corresponding to a wavelength of the elastic wave, and wherein at least one of the first and second electrode structures extend in the longitudinal direction from the first longitudinal edge to the second longitudinal edge substantially continuously.

Abstract: A reflection type liquid crystal apparatus comprising a liquid crystal panel (26) composed of a pair of first and second opposed plates (30, 32) for accommodating a liquid crystal (34) therebetween. A reflecting layer (28) is provided in the inner surface of the second plate, and the first plate is transparent. A common electrode (36) is provided in the first plate, and picture electrodes (38) are located in the second plate. A beam splitter (24) is located in front of the liquid crystal panel (26) for supplying polarized light to the first plate and for selectively transmitting polarized light emerging from the liquid crystal panel (24). The liquid crystal (34) comprises a nematic liquid crystal material having a positive birefringence and arranged in a homogeneous orientation with a constant director (n).

Abstract: A piezoelectric transformer includes a substrate of piezoelectric material, preferably a single crystal of LiNbO.sub.3. The substrate is uniformly polarized in a selected direction thereof and vibrated in a direction of the length thereof. An input voltage is applied across both sides of a portion of the substrate in a direction of the thickness thereof and thus excites a vibration by way of piezoelectric effect. Thereby another voltage is caused in the direction of the thickness of the substrate in a portion other than the portion to which the input voltage is applied, and taken out as an output voltage. As a result, it is possible to decrease the output impedance to obtain a large load current and thus fully heighten a step-up ratio of the piezoelectric transformer.

Abstract: An optical reader which comprises: at least one yellow LED array as a light source for lighting original material; an optical lens or fibers for guiding the light reflected from the original material; and an image sensor which changes the reflected light to signal waves. In embodiments of the reader, the light source includes both a yellow LED array and a green LED array with colored filters either provided over the LED arrays or on the optical lens or fibers.