Hitachi, Ltd.

Other

Hitachi Koki Co., Ltd.

Masuo Kasai

Takeshi Maeda

Shigeru Nakamura

Kiyoshi Matsumoto

Toshimitsu Kaku

Kazuo Shigematsu

Seiichi Mita

Yoshito Tsunoda

Masahiro Ojima

Koji Muraoka

Motoyasu Terao

Akira Arimoto

Seiji Yonezawa

Kunio Harada

Takeshi Mochizuki

Morishi Izumita

Takeshi Nakao

Toshiaki Tsuyoshi

Yoshizumi Eto

Kanji Kato

Hiroyuki Tsuchinaga

Yoshinori Miyamura

Makoto Nakura

Minoru Hiroshima

Masahiro Takasago

Yoshihiro Hamakawa

Mariko Umeda

Shigeru Yoshizawa

Minoru Seino

Eiichi Seya

Osamu Namikawa

Hiroshi Yasuoka

Motoo Uno

Kazutoshi Obara

Raiji Shimomura

Shuichi Morio

Kiyoo Takeyasu

Yasuhide Matsumura

Minoru Ohshima

Fumio Hara

Susumu Saitoh

A magnetic head is supported with variable stiffness for loading onto the disk surface and unloading off the disk surface. The magnetic head is attached to an end of a thin leaf spring which has been curved in advance, and the leaf spring is interposed between two flat plates, with one of the flat plates being slidable. With the slidable flat plate being moved to the position where the plate overlies a fitting section of the magnetic head, a head support point is provided at a first position with respect to the magnetic head, the thin leaf spring takes an extending straightened state, and at the same time, the thin leaf spring, two flat plates, and magnetic head fitting section form a unitary member with a high stiffness for supporting the magnetic head thereby to load the magnetic head onto the disk surface. With the slidable plate being moved in the opposite direction so as to free the curved section of the thin leaf spring, a second head support point provided at a position further away from the magnetic head than the first position, and the magnetic head is supported flexibly with a lower stiffness by the thin leaf spring. Since the thin leaf spring curves in a free state at this moment, the magnetic head which is attached to the end of the leaf spring is unloaded off the disk surface as if it is whipped up.

Magnetic head load/unload device, method and a magneto-optical disk

A focus error detecting method and an optical head using it. In the focus error detecting method, a light beam is emitted from a light source, the beam is given positive and negative astigmatism by a diffraction grating or an acoustooptic element in a focusing optical system, beams thus formed are focused on an information recording surface, the beams reflected from the information recording surface are received by photo-detecting elements in separated optics, the reflected beams with positive and negative astigmatism are compared with each other to take a difference in a focus error detecting circuit, and a focus error detecting signal is obtained on the basis of the difference. The focus for the optical head can be adjusted using the focus error detecting signal.

Focus error detecting method and optical head using the same

A light spot positioning method and apparatus for performing a seek operation of positioning a record/playback light spot at a desired track on a recording medium by a macro moving mechanism for an optical head and a micro moving mechanism mounted on the optical head or the base of the apparatus, and for selecting the bandwidth of the control servo of the micro moving mechanism to be higher than 10 KHz during a track pull-in operation. By selecting the bandwidth of control servo of the micro moving mechanism higher than 10 KHz, the track can be pulled in with the relative velocity between the track and the light spot remaining high. During a track following operation after the completion of the track access, the band of the control servo of the micro moving mechanism is changed to a low level of lower than 5 KHz.

Light spot positioning method and optical disc memory apparatus

A separation type optical head according to the present invention includes at least a light source portion for emitting collimated beams, a focusing device (a focusing lens) for focusing the collimated beams onto an information recording surface of an optical disc medium, a focal point control mechanism for the position of the spot on the information recording surface, and a photo-detection portion for receiving beams reflected by the information recording surface. The structure is divided into a fixed portion including the light source portion and the photo-detection portion and a movable portion including the focusing device (focusing lens) and the focal point control mechanism. At least the movable portion of the separation type optical head is movably accommodated n a frame (sealing case) for the optical head so as to prevent irregular vibrations of the movable portion due to high speed air flows or turbulence. Furthermore, a focal point control mechanism of an air float type may be employed in the movable portion of the separation type optical head so as to actively utilize the high speed air flow generated due to the rotation of the disc medium to perform a rough adjustment of the focal point of the focusing device.

Stack type optical disc apparatus, sealed and separate type optical head

A beam position control apparatus in which a light beam is led into a light detector from a light generating source through a movable reflector and positioning of the light beam is performed by a servo control circuit for feeding a signal from the light detector back to the movable reflector, comprises: an oscillator for oscillating in response to an initializing signal and moving the movable reflector to move the beam onto the light detector; and a control switch for separating the oscillator and the movable reflector from each other in response to the signal from the light detector, the oscillator and the control switch being arranged in the servo control circuit.

Beam position control apparatus

A recording/reproduction head incorporates an optical system which produces two light spots on an optical disk at positions spaced out from each other by, for example, half the radial span of the effective area of the disk. In recording or reproducing information using the two light spots, the inner light spot is moved to an unused track area provided in the innermost section of the disk, an auto-focusing servo system for the inner light spot is started, a control track provided near the unused area is read to judge the compatibility of the disk, and, only when the disk compatibility is verified, the outer light spot is moved to an unused track area provided in the outermost section of the disk, and an auto-focusing servo system for the outer light spot is started by making reference to a signal to the already operating inner auto-focusing servo system. Although the outer auto-focusing servo system is started at the outermost section where the vertical swing of the disk is pronounced, the disk swing can be inferred from the signal of the already operating inner auto-focusing servo system, and therefore it can be started stably even over the outer section with a large vertical swing at a timing of minimal swing imparted by the signal of the inner auto-focusing servo system.

Optical disk apparatus having auto-focusing servo systems for multiple

An optical tape apparatus having improved focus and tracking control. An optical head records, reproduces, or rewrites data on an optical tape by helically scanning the tape with a laser beam. A guide plate is disposed between the optical head and the tape to prevent the beam from becoming unfocused due to fluctuation of the tape cuased by an air film between the optical head and the tape. The optical head contains a semiconductor laser and an optical system exhibiting chromatic aberration for directing the laser beam onto the tape. The optical system includes a condenser lens for focusing the beam onto the tape. Fine focus control is achieved by changing the wavelength of the laser beam by directing part of the beam reflected from the tape back to the laser, thereby changing the focal point of the beam by virtue of the chromatic aberration of the optical system. Coarse focus control is achieved by mounting the condenser lens on a piezoelectric actuator which moves the consenser lens to focus the beam onto the tape. A recording head for recording timing marks and tracking signals on the tape is disposed in advance of the optical head. A reading head reads the timing marks and the optical head reads the tracking signals. The timing marks and tracking signals are used to control the operation of the apparatus such that the tape is transported with a constant speed and data on diagonal signal tracks on the tape is accurately recorded, reproduced, or rewritten.

Optical tape apparatus with a tracking control mechanism and/or a

An optical disk storage access method using a fine and coarse actuators for positioning a light spot to an intended track on the disk, wherein a pulse is generated each time the light spot has traversed a track, the pulses are counted to determine the distance from the current spot position to a target track, the fine actuator is activated depending on the measured distance, and the fine and coarse actuators are operated in unison so that the light spot is positioned to the target track.

Optical disc access method and optical disk storage using coarse and

Access method and information retrieval apparatus in which an external scale is used during accessing an optical head to a desired track on a rotating recording medium. The number of scale pitches to a target track on the external scale is detected and the speed of the head is controlled by the number of scale pitches. An eccentricity status of the rotating recording medium is previously detected and the number of scale pitches is corrected in accordance with the detected eccentricity status so that a distance of movement in a speed control is corrected and an access time is shortened.

Eccentricity correction during optical head accessing of a desired track

A method of accessing a rotary recording medium for positioning a head at a desired track on the rotary recording medium by using a coarse actuator and a fine actuator, comprising the steps of comparing an output signal produced from a detector for detecting movement of the fine actuator occurring immediately before initiation of an access operation of the coarse actuator with an output signal subsequently produced from the detector during the access operation of the coarse actuator to produce a comparison output signal, and locking the fine actuator at a state occurring immediately before the initiation of the access operation by driving the fine actuator on the basis of the comparison output signal to thereby suppress vibrations of the fine actuator due to translocations of the coarse actuator. An information memory apparatus utilizing the access method is also disclosed.

Disc accessing using coarse and fine actuators with the fine actuator

This invention relates to a track setting method for a tracking servo system in an optical disk device and a device therefor. According to this invention the track passage velocity when the light spot moves across the track is detected and setting of the light spot onto the track is performed under the condition that the passage velocity thus detected is lower than a predetermined velocity. In the case where the passage velocity is greater than the predetermined velocity, the light spot is forced to move so that the passage velocity is lower than the predetermined velocity and the light spot is set up thereafter.

Tracking servo setting method and apparatus

An optical system for recording and reproducing optical information. A line of synchronization pits for tracking and an information recording area are disposed alternately in advance. At the time of recording, a tracking signal is detected from the line of synchronization pits and while tracking in the information recording area by utilizing this signal, the information signal is recorded in the information recording area. Tracking control in tracking in the information recording area is stabilized by holding the tracking signal which is detected from the synchronization signal and by compensating for an electrical phase delay caused by the holding.

Phase compensation apparatus for an optical information recording and

A magnetic bubble information writing device capable of carrying out writing without erasing old information representing either '0' or '1' at a location, where new information is to be written, by means of only a single hairpin-like conductor loop is disclosed, in which the single hairpin-like conductor loop is disposed at a projecting portion of permalloy patterns, enclosing the portion.

Magnetic bubble information writing device

A joint mechanism of a manipulator, according to the present invention, consists of a first joint having its rotating shaft aligned with the Z-axis in the X-Y-Z Cartesian coordinate system established at a desired position in a working space, a second joint connected to the rotating shaft of the first joint and having its rotating shaft positioned within the X-Y coordinate plane, a third joint, connected to the rotating shaft of the second joint and having its rotating shaft aligned with the vector passing through the origin of the Cartesian coordinate system, and an arm assembly connected to the rotating shaft of the third joint and comprising a link mechanism which is driven so that a wrist connected to said arm assembly may be always moved on the prolongation line of the vector, to thereby provide a simplified joint mechanism of a manipulator having a redundant degree of freedom of the posture completely independent to the position of the wrist.

Joint mechanism of manipulator

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Hachioji, Japan

Masuo Kasai