Abstract: In a projection-type image display device, a driven member of a screen is displaced in a plane parallel to the screen. The driven member can be a Fresnel lens or a diffusing member. An elastic retaining unit holds the driven member in such a manner as to be capable of moving in the plane parallel to the screen, and a pair of driving sources applies driving forces in mutually intersecting directions to the driven member. A control circuit drives the pair of driving sources with driving waveforms having a prescribed phase difference therebetween so that the driven member makes continuous motion in a plane parallel to the screen when an image is projected.

Abstract: In a projection-type image display device, a driven member of a screen is displaced in a plane parallel to the screen. The driven member can be a Fresnel lens or a diffusing member. An elastic retaining unit holds the driven member in such a manner as to be capable of moving in the plane parallel to the screen, and a pair of driving sources applies driving forces in mutually intersecting directions to the driven member. A control circuit drives the pair of driving sources with driving waveforms having a prescribed phase difference therebetween so that the driven member makes continuous motion in a plane parallel to the screen when an image is projected.

Abstract: An operating mechanism having a guiding circular plate (9b) provided at a side surface of a gear wheel (9), an annular groove (15d) formed in a pinion (15) into which the guiding circular plate (9b) is fitted whereby the relative position in axial direction between the pinion (15) and the gear wheel (9) does not change even if there is an axial displacement of the gear wheel (9) or the pinion (15) due to a play. Accordingly, there is obtainable a stable angular position of the gear wheel (9) in the disconnection between the pinion (15) and a clutch driving element (16), via a cam constituted by a end-face cam (a projection) (9a) provided at a side surface of the gear wheel (9) and the clutch driving element (16).

Abstract: A process for preparing a quinone, which comprises reacting a polynuclear aromatic hydrocarbon and a ceric salt in an aqueous acid solution in the presence of an organic solvent selected from the group consisting of chlorobenzene and an alkylbenzene represented by the general formula: ##STR1## where each of R.sub.1, R.sub.2 and R.sub.3 is an alkyl group and the total carbon number of the alkyl groups is from 3 to 6.

Abstract: A scale deposition from an aqueous slurry of naphthoquinone and phthalic acid can be prevented by adding fine crystals of phthalic acid to the aqueous slurry of naphthoquinone and phthalic acid collected, which slurry is obtained by contacting a gas resulting from a catalytic gas phase oxidation of naphthalene with water or a mother liquor recycled. The fine crystals of phthalic acid have diameters of less than 100.mu., preferably 10 to 40.mu., and can be in an aqueous slurry of phthalic acid pulverized by a pulverizer.