摘要:
An objective lens actuator that can accommodate higher density and speed is provided by improving frequency characteristics of an objective lens.The objective lens actuator includes an objective lens, a cylindrical lens holder that holds the objective lens, and a reinforcement part disposed in an opening opposite to the objective lens of the lens holder. The reinforcement part has a size that occupies one third to one half of the cylindrical wall of the lens holder from the end of an aperture along the optical axis. In this range, the high order resonance frequencies of the lens holder can be increased, and therefore, it is possible to obtain an objective lens actuator that can minimize the vibration amplitude at the high order resonance frequencies.
摘要:
A synthetic cork stopper which has excellent gas-barrier properties and is satisfactory in sealing properties and suitability for opening. The synthetic cork stopper is obtained by foaming a composition including (a) an isobutylene-based block copolymer comprising a polymer block comprising isobutylene as its main component and a polymer block formed from a cationic polymerizable monomer ingredient in which isobutylene is not its main component; and a foaming agent.
摘要:
An objective lens actuator, having a small tilt of an objective lens, for driving the objective lens in a focusing direction and a tracking direction, so as to focus lights on a recording surface of an optical disc, as a recording medium of information, comprises therein: a magnet; a lens holder, which is configured to hold the lens thereon; and four (4) pieces of tracking coils are disposed in a line on a side surface of the lens holder for holding the objective lens thereon, facing to the magnet. And also, an objective lens actuator, having a small tilt of an objective lens, for driving an objective lens in a focusing direction and a tracking direction, so as to focus lights on a recording surface of an optical disc, as a recording medium of information, comprises therein: magnets, which are disposed on two (2) surfaces putting the objective lens therebetween; a lens holder, which is configured to hold the lens thereon; and four (4) pieces of tracking coils are disposed in a line on each of two (2) side surfaces of the lens holder for holding the objective lens thereon, facing to the magnets.
摘要:
A cap liner composition including (a) 100 weight parts of isobutylene-based block copolymer containing a polymer block based on isobutylene and a polymer block containing a monomer ingredient not based on isobutylene, and (b) 0.1 to 20 weight parts of lubricant added to the (a) isobutylene-based block copolymer, is provided. Also, a cap liner using the composition is provided. The thus formed cap liner that is used as a sealing material for a beverage cap has an excellent gas barrier property and preferable sanitary characteristics, and it can be opened easily in an actual use.
摘要:
An optical pickup in which the position of a magnet can be adjusted with respect to a yoke is provided. The optical pickup has an objective lens, a lens holder that holds the objective lens, a magnet disposed opposite to a side surface of the lens holder, and a yoke to the inside of which the magnet is attached. The yoke has an opening at least near the bottom of the magnet, through which the magnet can be visually observed from the outside of the yoke, the bottom being on the side of the yoke that is farther from an optical disc and the top being on the side of the yoke that is closer to the optical disc along the optical axis of the objective lens.
摘要:
In an object lens actuator, stiffness of a lens holder is improved and the higher order resonance frequency is sufficiently increased. The stiffness of the lens holder is improved by providing a flat plate perpendicular to the focusing direction between the side wall of a lens holding part and the outer sidewall along the tracking direction at approximately the middle of both ends of the lens holder along the focusing direction.
摘要:
An objective-lens driving apparatus includes permanent magnets on both ends of the movable unit, simultaneously, on the other side of the movable unit parallel to the tracking direction, also a permanent magnet at a position closer to the center of the movable unit. This configuration makes it possible to reduce each moment generated at each of a focusing coil and a tracking coil when an objective lens is displaced.
摘要:
Processes for producing an AB block copolymer, an ABA block copolymer or a multiblock copolymer are provided, which comprises adding an alkenyl-containing polymer (I) to a living or to an atom transfer radical polymerization system or a living cationic polymerization system.
摘要:
A cycloolefin copolymer resin composition having well-balanced transparency and impact resistance which comprises (A) a cycloolefin copolymer and (B) 1 to 100 parts by weight, per 100 parts by weight of said cycloolefin copolymer, of at least one rubber-like polymer selected from the group consisting of (B1) an aromatic vinyl-isobutylene copolymer and (B2) an aromatic vinyl-conjugated diene copolymer, wherein the difference in refractive index (nD) at 20° C. between the components (A) and (B) is at most 0.015 and the particle size of the component (B) dispersed in the component (A) is from 0.4 to 3 &mgr;m. The composition may further contain a core-shell polymer (C), whereby the impact resistance can be further improved. The composition is prepared by kneading the above components at an elevated temperature optionally in the presence of an organic peroxide.
摘要:
In an optical disk drive using as a light source a semiconductor laser having a main electrode and a plurality of subsidiary electrodes, a wave front of a generated laser beam is modulated by controlling injection currents to the plurality of subsidiary electrodes, in accordance with a change in signal outputs when the wave front is modulated, a tilt is detected between a direction normal to the surface of an optical disk and an objective lens optical axis, and in accordance with the detected tilt, the injection currents to the semiconductor laser are determined to correct the tilt. Since the tilt is detected and corrected through electrical modulation, the system can be made compact without using new components for tilt detection, and high speed control up to a high frequency becomes possible because there is no limit of the control bandwidth to be caused by sub-resonances in a high frequency band, like a mechanical actuator.