Abstract: In the optical pickup unit configured to guide a laser beam emitted from a laser source to an objective lens, to converge the laser beam with the objective lens to be irradiated to a disk, and to guide the laser beam reflected and returned by the disk to the photo detector including a light reception region constituted by a plurality of segments, the photo detector is disposed with each amplifier corresponding to each segment of the light reception region, is disposed with each output terminal that outputs each light reception output corresponding to each segment from the photo detector via each amplifier, and is disposed with an output setting circuit that sets each light reception output from each of the output terminals by changing the gain of each of the amplifiers and/or by attenuating the input or output of each of the amplifiers with an attenuator.

Abstract: In the optical pickup unit configured to guide a laser beam emitted from a laser source to an objective lens, to converge the laser beam with the objective lens to be irradiated to a disk, and to guide the laser beam reflected and returned by the disk to the photo detector including a light reception region constituted by a plurality of segments, the photo detector is disposed with each amplifier corresponding to each segment of the light reception region, is disposed with each output terminal that outputs each light reception output corresponding to each segment from the photo detector via each amplifier, and is disposed with an output setting circuit that sets each light reception output from each of the output terminals by changing the gain of each of the amplifiers and/or by attenuating the input or output of each of the amplifiers with an attenuator to correct each light reception output from each of the output terminals with the output setting circuit depending on an output difference generated in each

Abstract: A rolling bearing provided with measures to suppress a rise in temperature. The rolling bearing comprises inner and outer races, a plurality of rolling elements 16 interposed between the inner and outer races, and a cage for retaining the rolling elements 16. On the use conditions that the direction of load is stationary to the outer/inner race and rotational with respect to the inner/outer race of the two races, the cage 17 is guided for rotation with outer/inner regions of its pocket surfaces in contact with the rolling elements 16. It is also intended to facilitate satisfactory lubrication by means of grease and to enhance the durability and life of the bearing. For that purpose, a bearing 21 incorporated into a main motor is arranged with both end faces adjoining end members 24 and 25 that have grease pockets 22 and 23 formed therein, respectively.

Abstract: A ball screw for a vacuum apparatus which includes a screw shaft having a spiral inner raceway formed on an outer peripheral surface thereof, a ball nut having a spiral outer raceway formed on an inner peripheral surface thereof, a plurality of balls disposed in a spiral space defined between the inner raceway and the outer raceway, and circulating members connecting ends of the spiral space to each other to define a continuous ball circulating passage. The plurality of balls are first balls formed of high polymer material containing polytetrafluoroethylene as a main component and second balls formed of either a metallic material or a ceramic material. The first balls circulate through the circulating passage together with the second balls. The second balls have lubricating films of crystalline polytetrafluoroethylene formed on the surface thereof.

Abstract: A linear ball bushing comprises a cylindrical retainer (1) having a number of pockets (1a), a number of balls (2) received in the pockets (1a), respectively, and a retaining sleeve (3) having a number of retaining holes (3a) corresponding to the pockets (1a) in the retainer (1) center (O3) of the retaining hole (3a) being offset by a distance (S) from center O1 of the pocket (1a) axially of the retainer so that a portion of peripheral edge of the retaining hole overhanging the pocket (1a), thereby preventing the balls (2) from dropping out of the pockets (1a).

Abstract: The outer ring 3 is formed of COPNA resin. The inner ring 1 and balls 4 are formed of martensitic stainless steel SUS440C or the like, and the retainer 5 is formed of SUS304 or the like.

Abstract: The raceway surfaces of the inner and outer rings 1 and 2 and the surfaces of the rolling elements 3 are formed with lubricating films 1a, 2a and 3a of polytetrafluoroethylene having average molecular weight of not more than 5000 {PTFE (A)}. PTFE heretofore used for rolling bearings is a polymer having average molecular weight of more than 1.times.10.sup.5 mostly 1.times.10.sup.6 -1.times.10.sup.7, but PTFE(A) is very low in shear strength and soft as compared with PTFE polymer.