Abstract: An optical transmission module having optical fibers and an optical semiconductor device with light couplings between the optical fibers and conversion parts of the optical semiconductor device, which conversion parts either convert electrical signals into optical signals or convert optical signals into electrical signals, includes a guide substrate having grooves which hold the optical fibers, and at least one positioning part formed on and protruding from the optical semiconductor device and having a width smaller than that of the grooves, wherein the optical semiconductor device is attached to the guide substrate such that the at least one positioning part fits into the grooves, so that the conversion parts face end surfaces of the optical fibers to establish the light couplings.

Abstract: An image forming apparatus includes a microcomputer. The number of image forming operation of a photosensitive drum is counted by a counter as a copy quantity, and data of the copy quantity is applied to the microcomputer. By referring to a copy quantity-voltage table, voltage setting data according to the copy quantity is applied by the microcomputer to a bias voltage source so that the bias voltage source applies a required bias voltage according to the voltage setting data to a conductive substrate of the photosensitive drum.

Abstract: An image forming apparatus includes a semiconductor laser unit for emitting a laser beam, a photosensitive drum which rotates in a first direction, a scanning optical system for making the laser beam scan the photosensitive drum in a second direction perpendicular to the first direction, wherein an electrophotography process is carried out on the surface of the photosensitive drum, a data generator for generating intensity data for each dot in an image in accordance with image information supplied from an external controller, and a laser driver for outputting a driving signal which drives the semiconductor laser unit, the driving signal having a pulse width and a level for each dot in an image, the pulse width being a predetermined value less than a value corresponding to an interval between adjacent dots formed in a direction parallel to the first direction, and the level corresponding to the intensity data generated by the data generator.

Abstract: A steel oil ring assembly having an upper rail, a lower rail and an annular space-expander embraced by the rails and having radially extending or axially extending corrugations. The spacer is split at one circumferential location to form abutting end portions which come into pressured contact with each other at a force point located on a plane passing through the centers of the corrugations that extends in an axial direction for radially extending corrugations and in a radial direction for axially extending corrugations. The free ends of the abutting end portions of the spacer form an opening having an angle of 10.degree..+-.9.degree. extending outwardly from the force point.

Abstract: A gas expansion engine in a refrigerating cycle is disclosed and, in particular, a gas expansion engine is provided which includes a cylinder and piston to define a variable-capacity expansion chamber therebetween. The piston is reciprocably inserted into the cylinder and is coupled to a motion conversion mechanism through a piston rod. One ball-and-socket joint is provided at at least one of a location between the piston rod and the piston and a location between the piston rod and the motion conversion mechanism.

Abstract: A steel oil ring assembly having an upper rail, a lower rail and an annular space-expander embraced by the rails and having radially extending or axially extending corrugations. The spacer is split at one circumferential location to form abutting end portions which come into pressured contact with each other at a force point located on a plane passing through the centers of the corrugations that extends in an axial direction for radially extending corrugations and in a radial direction for axially extending corrugations. The free ends of the abutting end portions of the spacer form an opening having an angle of 10.degree..+-.9.degree. extending outwardly from the force point.

Abstract: A piston is eccentrically arranged in a cylinder along its axial direction and can be rotated relative to the cylinder. Part of the piston is in contact with the cylinder's inner surface. First and second helical grooves are formed in the piston's outer surface and separated at its central portion, the pitches of the grooves being gradually increased from both end portions to the center portion of the piston. First and second blades are inserted in first and second grooves so as to be moved in and out of the grooves with the outer edges of the blades contacting the inner surface. The blades partition a space between the cylinder and the piston into a plurality of operation chambers with volumes corresponding to the gradual pitch increases.

Abstract: A fluid compressor includes a cylinder and a columnar rotary rod. The rod is arranged in the cylinder so as to extend in the axial direction thereof and be eccentric thereto, and orbitable relative to the cylinder without rotation with respect to the cylinder while part of the rod is in contact with the inner circumferential surface of the cylinder. A spiral groove is formed on the outer circumference of the rod and a spiral blade is fitted in the groove. The space between the outer circumference surface of the rod and the inner circumference surface of the cylinder is divided by the blade into a plurality of operating chambers. The groove has an overall length larger than that of the blade by a predetermined length so that the blade is displaceable relative to the rod in the radial and circumferential directions of the rod without sliding on the inner circumferential of the cylinder.

Abstract: A two-cylinder type rotary compressor with a more durable bearing portion and a higher operational efficiency is provided. In addition, the two-cylinder type rotary compressor significantly reduces vibration and noise generated therefrom.

Abstract: A scroll member comprising a metallic end plate having a spiroidal groove on one side thereof, and a through-hole communicating with the groove, and a resin wrap joined to the groove of the end plate so as to protrude from the surface of the end plate. The wrap being formed by injection molding, and the through-hole and the groove being filled with part of the wrap.

Abstract: In a scroll compressor, the side of the orbiting end plate away from the compression chambers is slidably supported by an annular protusion formed in the frame. A lower pressure chamber is formed on the radially outer side of this annular protrusion, and an Oldham's ring is fitted inside the lower pressure chamber.

Abstract: In a scroll compressor, at least one suction port for gas is opened in a stationary end plate which has a spiral wrap. Gas is drawn directly into the compression chambers from the suction port. In addition, the suction port has an opening straddling both the radially extending surface of the stationary end plate at the outermost circumference of the compression chambers and the compression chamber side wall that is perpendicular to the radially extending surface, and the opening area of the suction port is relatively large.