Abstract: Herein disclosed is a method for manufacturing a base plate for a recording disc, which comprises steps of polishing the surface of the base plate of glass or aluminum, thereafter dispersing uniformly micro-crystals on the polished surface to form a portion where the micro-crystals are in contact with said polished surface, and subjecting the base plate to etching treatment with an etching agent in a gas phase or a liquid phase. Also disclosed is a base plate for a recording disc, which is obtained by uniformly dispersing micro-crystals on the surface of the base plate and subjecting the same to etching treatment, said base plate having very fine convexities and concavities on its surface.

Abstract: A substrate including a disk having a pair of opposed faces and being coined to provide a sub-micron flatness and smoothness for the disk faces. The coined disk can then be coated with a layer of storage material and used as a storage medium. Apparatus and a method for forming the coined substrate includes means for moving a plurality of disks along a predetermined path after the disks have been formed by blanking or stamping. The disks are cleaned before being coined and then stacked into containers which can be closed for transit to a point of use. The coining of the disks and the placement of the disks in containers is done under clean room conditions and the resulting coined substrates are free of flaws and defects encountered with the practice of conventional substrate forming techniques.

Abstract: A method of manufacturing a substrate for a memory disk characterized in that a blank material comprising a non-magnetic metal substrate covered with a non-magnetic metal as an underlayer is subjected to a coining operation by two dies, i.e. upper and lower dies each having flat compressing surface and a certain kind of textured design formed thereon within an apparatus including a mandrel and a die ring arranged to limit the spreading extent of the material whereby a surface having ultra-preciseness and simultaneously impressed texture design is obtained.

Abstract: A method for manufacturing a metal substrate for a memory disk wherein a metal blank material (6) is sandwiched between two dies within a metal mould (3) limiting the extent to which the material spreads, using a core member (4) if necessary, each of the dies having a flat and smooth working surface, the compression force and sheet gauge reduction ratio being regulated or the surface roughness and amount of coating lubricants employed being regulated.

Abstract: A method of manufacturing a substrate for a memory disk characterized in that a blank material comprising a non-magnetic metal substrate covered with a non-magnetic metal as an underlayer is subjected to a coining operation by two dies having flat compressing surfaces within an apparatus including a mandrel and a die ring arranged to limit the spreading extent of the material whereby a surface having ultra-preciseness is obtained.

Abstract: A human body protector comprising a front layer and a rear layer. In this protector, each layer is comprised of a plurality of segments having a regular hexagon shape and arranged by placing circumferential edges of adjacent segments in contact with each other in a state wherein spaces between the adjacent segments are substantially eliminated, and joining lines between the adjacent segments of one layer are covered by the segments of the other layer, and through apertures at the joining points, existing because joining lines of the segments of one layer overlap the joining points of another layer, are closed by a retaining members. The construction of the protector of the present invention provides an excellent protection against penetration of the protector by a sharp pointed blade, such as an ice pick.

Abstract: An acrylic resin article comprising a methyl methacrylate polymer and dibenzylidene sorbitol or its derivative as essential ingredients; and a process for producing an acrylic resin article, which comprises putting a composition comprising a methyl methacrylate monomer or a mixture of a methyl methacrylate polymer and a methyl methacrylate monomer and dibenzylidene sorbitol or its derivative in a mold, and thereafter polymerizing the methyl methacrylate monomer in the composition.

Abstract: A composition consisting essentially of solid powdery dibenzylidene sorbitol and a higher fatty acid, the surface of the dibenzylidene sorbitol being coated with the higher fatty acid; and a process for producing dibenzylidene sorbitol powder having a coating of a higher fatty acid on its surface, which comprises a step of forming an aqueous emulsion of the higher fatty acid by adding an alkali to an organic solvent solution or hot molten mass of the higher fatty acid partially saponify the higher fatty acid and dispersing the resulting mixture of the higher fatty acid and its saponification product in water, a step of coating the surface of dibenzylidene sorbitol powder with the higher fatty acid by adding the dibenzylidene sorbitol to the resulting emulsion, and a step of separating the solid from the mixture, drying the solid and recovering the dried product. The transparency and rigidity of a polyolefin resin is improved by addition of aforesaid dibenzylidene sorbitol composition.

Abstract: In a process for preparing dibenzylidenesorbitol by dehydrocondensation of 1 mol of sorbitol with 2 mols of benzaldehyde in the presence of an acid catalyst, the improvement in which the reaction is carried out in two stages, the first-stage reaction comprising reacting the reactants with heating at a temperature of 50.degree. to 70.degree. C., the first-stage reaction being shifted to the second-stage reaction by adding water and an additional amount of an acid catalyst when the conversion of sorbitol to dibenzylidenesorbitol reaches 10 to 40%, and the second-stage reaction comprising of reacting the mixture in the suspended state at ordinary temperature in 2.5 or more parts by weight, per part by weight of sorbitol, of an aqueous reaction medium, and the resulting dibenzylidenesorbitol is obtained as an aqueous suspension.

Abstract: Disclosed is a device for measuring the rotational speed of a diesel engine. The device comprises a sensor element of electrostrictive effect type adapted to be detachably mounted on a delivery pipe of a fuel injection system of the diesel engine and having an intrinsic resonance frequency between 100 KHz and 10 MHz. A high frequency electric signal is transmitted from the sensor element in response to a high frequency oscillation generated in the fuel within the delivery pipe when fuel is injected. The device further comprises an amplifier, a converter, a wave shaping circuit, an integral circuit and an indicator. The high frequency electric signal is processed in the device and the rotational speed of the diesel engine is indicated by the indicator.