Abstract: In a dynamic pressure bearing, a dynamic pressure-generating groove is provided to one of a thrust bearing surface and a part of a rotator facing the thrust bearing surface on one of a first and second thrust bearings, and a thrust bearing surface and a part of the rotator on the other one of the first and second thrust bearings which is not provided with the dynamic pressure-generating groove are smoothed so that the smoothed surfaces are formed.

Abstract: In an injection molding method, a resin is injected into a cavity of a mold in such a manner that a pressure ratio of a cavity surface pressure in the cavity to a cylinder pressure of an injection molding device is not less than 0.65, a first pressure keeping process to keep the cylinder pressure at a constant is conducted after the filling step, the cylinder pressure is increased so that the cavity surface pressure in the cavity is 0.95 times or more larger than the pressure at the time that the cavity has been filled with the resin; and a second pressure keeping process to keep the changed increased pressure at least until a cavity surface temperature becomes lower than a glass transition temperature of the resin.

Abstract: A method for cutting a surface of a base of a photoreceptor for electrophotography is disclosed. The method comprises steps of:(a) supplying an aqueous cutting fluid to the surface of the photoreceptor base;(b) cutting the surface of the photoreceptor base by a cutting tool comprising a single crystal diamond.

Abstract: A dynamic pressure generating bearing includes a rotational body, a radial bearing provided adjacent to a center of the rotational body to rotatably support the rotational body around the radial bearing and at least one thrust bearing provided on one end of the radial bearing. When the rotational body is stably rotated, a minimum clearance generated between the rotational body and the thrust bearing is always greater than a minimum clearance generated between the rotational body and the radial bearing.

Abstract: A cutting apparatus for finishing a surface of a substrate of a photoreceptor drum of an image forming apparatus estimates a finish state of the surface on real time with the finishing. The cutting apparatus has a detector to detect a cutting force to a cutting tool from the surface in finishing, a memory to store a cutting force pattern to distinguish the finish state of the surface, comparator means to compare the detected cutting force with the stored cutting force pattern and judging means to judge the finish state of the surface along with the progress of the cutting process.

Abstract: A polygon mirror is produced using a diamond tool. The diamond tool includes a major cutting edge and an end cutting edge. The major cutting edge is formed straight by a rake face and a side flank, the major cutting edge having a first side and a second side. The end cutting edge is formed straight by the rake face and a front flank, the end cutting edge having a third side. A microscopic cutting edge is arranged between the second side and the third side so that the major cutting edge and the microscopic cutting edge together create a first corner at the second side, and the end cutting edge and the microscopic cutting edge create a second corner at the third side. The rake face is inclined downward from the second corner to the first side. The microscopic cutting edge is between 0.1 mm and 0.4 mm in a direction of the end cutting edge. The microscopic cutting edge at the first corner is swept back by an amount between 0.21 .mu.m and 0.6 .mu.

Abstract: In machining a substrate surface of a photoreceptor by the use of a cutting machine which supplies cutting lubricant from a reservoir to a cutting tool of the cutting machine, the method comprises a measurement of a cutting tool temperature by a sensor and a control of both the temperature of cutting lubricant and a flow rate thereof. The control is responsive to the cutting tool temperature and suppresses a temperature fluctuation of the cutting tool.

Abstract: A method of surface-processing a photoreceptor base including aluminum material for electrophotography on a lathe, in which a surface of the base is cut by a cutting tool having a sintered polycrystalline diamond body while cutting fluid, composed of water, an aqueous solution of a surface-active agent or an aqueous solution of a water-soluble organic solvent, is being supplied to the surface of the base frame.

Abstract: In a method of manufacturing a photoreceptor base drum by a lathe-turning machine in which a cutting tool is brought in contact with a surface of the base drum and travels in the axial direction to finish the surface of the base drum into a mirror-like surface, a main cutting edge formed by a rake surface and a front flank surface on the cutting tool is shaped as a curved surface with a radius of curvature of 0.15 to 3.5 .mu.m, and the rake surface and the front flank surface are shaped to smoothly continue to the curved surface of the main cutting edge.

Abstract: An optical beam scanning apparatus wherein a beam shaping device for forming a flat light beam which has a large width in the scanning direction and which is substantially parallel with the direction of the optical axis is disposed between a light source and rotary polygonal mirror, and a cylindrical lens bent to have both ends in the longitudinal direction thereof approaching to the scanned plane is disposed between a condensing lens for condensing the light beam reflected by the rotary polygonal mirror and a scanned plane in the vicinity of the latter. The rotary polygonal mirror and the scanned plane are arranged to have a conjugate relation with each other from geometrical optics. The light beam is converged so as to generate the beam waist near the scanned plane.

Abstract: An optical beam scanning apparatus wherein a beam shaping device for forming a flat light beam which has a large width in the scanning direction and which is substantially parallel with the direction of the optical axis is disposed between a light source and rotary polygonal mirror, and a cylindrical lens bent to have both ends in the longitudinal direction thereof approaching to the scanned plane is disposed between a condensing lens for condensing the light beam reflected by the rotary polygonal mirror and a scanned plane in the vicinity of the latter. The rotary polygonal mirror and the scanned plane are arranged to have a conjugate relation with each other from geometrical optics. The light beam is converged so as to generate the beam waist near the scanned plane.