Abstract: An electrode structure disposed in a vacuum switch generally comprises a pair of relatively separable electrodes and a pair of contacts provided on the opposing surfaces of the electrodes and surface areas of the contacts are selected to be smaller than the surface areas of the electrodes. The vapor pressure P.sub.0 and specific resistance .rho..sub.0 of the electrode material and the vapor pressure P.sub.1 and specific resistance .rho..sub.1 of the contact material are held in a relation ##EQU1## and values representing specific heat, heat of fusion and heat of evaporation of the contact material are 100.+-.20% of those of the electrode material except a portion on which the contact material is provided.

Abstract: A stepping motor in which a rectangular stator core in the shape of a square frame has poles in the center of the inner side edges of sides thereof, four coils are wound on the poles of stator core, and a rotor is disposed in the space surrounded with the coils and having the height of each of poles being made 0.24 to 0.5 times as much as the outside diameter of the rotor. Each of poles has at the end thereof a plurality of projections according to a step angle. The rotor has projections on the peripheral surface thereof according to the step of the pole.

Abstract: A DC circuit breaker of the type using a blown arc-extinguishing gas is disclosed which allows for reliable fast interruption of DC currents through the provision of arc extension current paths. The extension current paths are relatively long and are bent after the incidence of the arc-extinguishing gas on the arc. The arc is formed to extend for a long distance in a loop configuration. An auxiliary electrode short-circuits the extended arc with one auxiliary electrode being provided for each extension current path.

Abstract: A guest-host liquid crystal display device is disclosed which undergoes a focalconic-homeotropic phase transition. The device has a guest-host material layer including (a) a nematic liquid crystal having a positive dielectric anisotropy, (b) an optically active material for putting the nematic liquid crystal in a cholesteric condition, and (c) a pleochroic dye, and has an electrode means for establishing an electric field in the material layer in order that the material layer undergoes the phase transition from the cholesteric condition to the homeotropic condition. Liquid crystal molecules in contact with the surface of the electrode are oriented with their longitudinal axes perpendicular to the electrode surface, with an orientation treatment carried out in the electrode surface or by an orientation film provided on the electrode surface. Thus, the material layer assumes the focalconic condition in the absence of the electric field. A chiralnematic compound is employed as the optically active material.