Matsushita Electric Industrial Co., Ltd.

Noboru Kikuchi

Tohru Nakamura

Akira Kurahashi

Hironori Tomita

Toshiyuki Shimada

Kazuhiro Aoki

Osamu Mizuno

Hideki Aikoh

Kanji Wakabayashi

Masanari Mohri

Masayuki Shinoda

Yasuaki Edahiro

A lens drive device for an optical information recording and/or reproducing head, which has a cylindrical lens holder for the support of an objective lens assembly and a tubular guide bearing receiving the lens holder for sliding and rotary motions in a direction parallel to and about the longitudinal axis of the lens holder. The device also has magnetic yokes positioned on respective sides of the guide bearing and each having tracking and focusing coils wound therearound. The lens holder has two permanent magnets embedded therein with their respective different poles exposed radially outwardly from a peripheral surface of the lens holder. The guide bearing has two windows defined therein at respective locations corresponding to the respective positions of the permanent magnets in the lens holder. When the focusing coils on the respective yokes are energized, the lens holder can be driven in a focusing direction parallel to the longitudinal axis of the lens holder, while when the tracking coils on the respective yokes are energized, the lens holder can be driven in a tracking direction generally perpendicular to the longitudinal axis of the lens holder.

Lens drive device with lens holder carrying drive flux generating magnets

From the start of descending of a disk-shaped recording medium in a direction of approaching an objective lens in the optical axis direction by a loading mechanism until it is set at a specified position with respect to a spindle motor, a DC current is supplied to an optical axis direction driving coil through an evading current feeding circuit in a direction for a movable part to depart from the disk-shaped recording medium, and the movable part is located at the remotest position from the disk-shaped recording medium due to an electromagnetic force generated by the DC current flowing in the optical axis direction driving coil and a permanent magnet, so that the disk-shaped recording medium and the objective lens will not collide against each other even if an objective lens with a short working distance is used.

Objective lens driving apparatus

A tracking control apparatus of an optical signal recording/reproduction apparatus, records and reproduces a data signal by causing a light spot focused on an optical recording medium to trace data-recording tracks and then accesses the light spot to a desired track. The tracking control apparatus varies a tracking-servo target value in a direction of performing the track-jumping operation, and then, if the tracking error signal exceeds a predetermined position level, the tracking control apparatus repeatedly varies the polarity of the tracking error signal until the light spot eventually arrives at the target track subject to the track-jumping operation. By virtue of the structure mentioned above, the tracking control apparatus can stably perform the track-jumping operation even when external disturbances, such as vibration, occur in the servo system.

Tracking control for optical information recording and reproducing

An equalizer apparatus is applied to a DBF disk recording medium in which a sampling clock is reproduced from clock pits recorded on the disk recording medium. A fixed coefficient equalizer includes an analog to digital converter, a memory and a two-dimension equalizer. The fixed coefficient equalizer suppresses interference from adjacent tracks and reduces the error rate of the reproduced data caused by crosstalk even in the case of a narrow track pitch. Further, by adding to the equalizer a sign detector, a FIR low-pass filter and a coefficient control circuit to form a variable coefficient equalizer, interference fluctuation attributed to the linear recording density, recording power irregularity, light spot shape, tracking error, etc., can be automatically compensated to suppress the equalization error caused by such fluctuation. Further, using the variable coefficient equalizer, clocking timing errors and fluctuations can be automatically and efficiently compensated.

Data recording/reproducing apparatus with two-dimensional equalizer for

A magneto-optical data recording and reproducing device for storing data in a data memory medium which applies modulation to a plane of polarization, erasing data therefrom and reproducing data stored therein, comprises a light source for emitting a light beam with linear polarization, a light spot forming means for condensing the light beam emitted from the light source and forming a light spot on the data memory medium, a beam splitting means, located between the light source and the light spot forming means, to which reflected light beams from the data memory medium are applied and splitted, a beam detecting prism, to which light beams splitted by the beam splitting means are applied, providing the polarizing function that a predetermined first pencil of light beam with linear polarization is reflected while a second pencil of light beam with linear polarization crossing the first pencil at right angles is transmitted, a beam splitting prism, being located near or adhered to the beam detecting prism, for splitting the second pencil of light beam with linear polarization transmitted through the beam detecting prism into two subpencils with approximately the same quantity of light, reflecting the splitted subpencils and then re-allying them to the beam detecting prism to form two optical axes extending along approximately the same direction as that of the first pencil of light beam with linear polarization, at least one or more photo detector to which a plurality of light beams having passed through the beam detecting prism and the beam splitting prism are applied, a data retrieval unit for retrieving data in the data memory medium according to output of the photo detector, a tracking servo unit to which a tracking error signal picked up by the output of the beam detector is applied, and a driving means for driving at least the light spot forming means in response to an output signal from the tracking servo unit.

Magneto-optical data recording and reproducing device

An optical head equipped with a tracking error detector to obtain a tracking error signal for tracking servo. The detector includes a photodetector having a light-detecting region on which a light spot with a predetermined diameter is formed by a reflected light beam from a recording medium. The region is divided by a first division line into two which are further divided by second and third division lines so as to form first to fourth subregions, the first and second subregions being adjacent to each other with the first division line being interposed therebetween, the third subregion being adjacent to the first subregion, and the fourth subregion being adjacent to the second subregion. The separation between the second and third division lines is determined so that the sum of the light receiving quantities of the first and fourth subregions is substantially equal to the sum of the light receiving quantities of the second and third subregions when the objective lens is shifted from its neutral position. Electric signals produced in correspondance with the light receiving quantities are supplied to a differential amplifier to take a difference between a sum signal of the signals due to the first and fourth subregions and a sum signal of the signals due to the second and third subregions.

Optical head with tracking error detecting system

An optical head and supporting apparatus has an optical head for irradiating a parallel beam in a direction perpendicular to a recording surface of an optical disk, an objective lens rigidly mounted on the optical head for receiving the parallel beam from the optical head, tracking drive coils for driving the optical head over the whole recording range in a first direction transverse to the recording tracks of the optical disk, focusing drive coils for driving the optical head in a second direction perpendicular to the recording surface of the optical disk, and a support mechanism made of wire-shaped elastic bodies for supporting the optical head freely movably in the first and second directions over the whole recording range in the first direction of the optical head. The support mechanism is fixedly mounted through elastic bodies on a part of a structural body independent of movement of the optical head. Seek, tracking and focusing movements of a beam spot can be achieved in such a way that the wire-shaped eleastic bodies are elastically deformed by forces developed through the tracking drive coils and focusing drive coils thereby to move the optical head two-dimensionally.

Optical head supporting apparatus

A magneto-optical recording and/or reproducing apparatus includes an optical head for providing a light spot for recording, reproducing and erasing of a magneto-optical disc, a magnetic head which is disposed at a position opposing the optical head with the magneto-optical disc therebetween and which provides a magnetic field for recording and erasing while maintaining a substantially constant distance from the magneto-optical disc by effecting a lift obtained by an air flow generated by the rotation of the disc, a loadbeam which has the magnetic head on its one end and serves to provide a force caused by elastic deformation to the magnetic head to thereby be balanced with the lift thus obtained, and a moving mechanism connected to the loadbeam. Approaching or evading the magnetic head to or from the magneto-optical disc can be realized by deforming the moving mechanism.

Magneto-optical recording and reproducing apparatus having magnetic head

A signal recording/reproducing apparatus equipped with a recording head section for recording signals on a recording medium and a reproducing head section for reproducing the signals recorded on the recording medium. The recording head section is arranged to record the signal to form N recording sub-tracks on the recording medium and the reproducing head section has M reproducing sub-heads which trace the N recording sub-tracks to reproduce the recording signal. The pitch of the M sub-heads thereof is equal to a pitch of the recording sub-tracks and the number M of the sub-heads is greater than the number N of the recording sub-tracks. The reproducing head section is coupled to a reproduction signal detecting section which is turn eliminates the interference and the crosstalk between adjacent tracks from the reproduced signal due to the reproducing head section. This arrangement allows narrowing the track pitch to increase the recording capacity and extremely improving the transfer rate concurrently with the elimination of the interference between the adjacent codes and crosstalk between the adjacent tracks.

Signal recording/reproducing apparatus

A data demodulation apparatus applicable to a playback input signal from a digital recording apparatus, which executes A/D conversion of the input signal with a sampling period that is equal to the bit separation of that signal, and obtains phase data for reproducing the phase of the clock signal component of the input signal each time that a '1' state bit is detected in a sampling period. For each sampling period, or set of successive sampling periods, data values are derived which respectively represent a number of bit positions of the input signal within that period and the presence or absence of '1' state bits in the period, and these data values are converted to serial form to respectively constitute a reproduced clock signal and a detected data signal.

Data demodulation apparatus

An objective lens actuator is provided which is equipped with an actuating mechanism for actuating an objective lens mounted on a lens holder of an apparatus adapted to write or read information into or from a recording medium. The actuator moves the lens and its holder in two directions, one direction being substantially parallel to a surface of the recording medium such that the objective lens makes turning motion about a pivot axis oriented substantially normal to the surface of the recording medium and the other direction being vertical, with the lens and holder sliding vertically relative to the pivot axis. The actuator is equipped with at least one parallel driving coil for driving the movable section in the parallel direction and with at least one parallel driving magnetic circuit for imparting a magnetic flux to the parallel driving magnetic circuit. The actuator is arranged such that both drive forces, which are generated as a result of respective actions of electric currents flowing through at least two faces of the parallel driving coil and magnetic fluxes of the parallel driving magnetic circuit, constitute turning forces for turning the objective lens about an axis in the same rotational direction, thereby enhancing driving precision.

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Hirakata, Japan

Noboru Kikuchi