Abstract: An overwritable optical disk apparatus in which a finite conjugate optical system is employed. The apparatus comprises an optical head for converging diffused light from a light source onto an optical disk for performing data write/read operation, a driving unit for rotating the disk and a beam splitter for guiding the light reflected from the optical disk to a photodetector for detecting light reflected from the optical disk. Influence of disk displacement occurring in accompanying the rotation of the disk and disk eccentricity are suppressed to a minimum by encasing rotatably the optical disk within a credit card size casing which is adapted to be loaded and held stationarily in the optical disk apparatus. Thin structure of the optical head and miniaturization of the optical disk apparatus are realized with light utilization efficiency for data write/read operation being increased.

Abstract: The information processor uses a portable memory which is able to be overwritten by laser power modulation system. The memory includes a disk type recording medium incorporated rotatably in a thin case, and carries out write/read/erase by means of a first magnetic field application device, a second magnetic field application device, and an optical head radiating light through this case.

Abstract: A low pressure container type rolling piston compressor which includes a compression element, a motor element, a rotary shaft with an eccentric portion driven by the motor element, a cylinder for receiving therein the eccentric portion of the rotary shaft, a rolling piston having an inner circumference to which the eccentric portion is fitted and an outer circumference which rolls along the inner wall surface of the cylinder, a vane having an end which is in contact with the outer circumference of the rolling piston to divide the inner space of the cylinder into a high pressure chamber and a low pressure chamber, a pair of bearing plates for closing both open ends of the cylinder, a sealing container housing the above-mentioned structural elements and storing at its lower part a lubricating oil wherein a pressure in the sealing container is the same as that in the low pressure chamber and wherein an oil supplying passage is formed in either one of the pair of bearing plates for closing both open ends of the c