Olympus Optical Company, Ltd.

Ken Ohshima

Masaharu Sakamoto

Yoshiaki Ikeda

Kenji Kimura

Shoji Yoshikawa

Kunio Yamamiya

Hiroshi Kodama

Ken Satoh

Toshikazu Kato

Kiichi Kato

Sinichi Saitou

Seizo Watanabe

Hideyuki Kenjyo

Toyoaki Takeuchi

Hiroo Okada

Tsutomu Shibata

Masuo Okumura

Jun Sakashita

An optical recording/reproducing apparatus includes a pickup with a laser light source, an objective lens and lens drive coil for moving the optical axis of the laser beam transmitted through objective lens, a carriage drive voice-coil motor for moving a carriage with the pickup mounted thereon to move the laser beam transmitted through the objective lens, and tracking apparatus for operating both the lens drive coil and the carriage drive voice-coil motor. The tracking apparatus includes a lens servo stable detecting device for detecting that the laser beam from the objective lens has reached a desired track, apparatus for turning on a servo control loop with the lens drive coil in response to a tracking instruction, and apparatus for turning on a servo control loop with the carriage drive voice-coil motor in response to a detection output from the lens servo stable detecting device.

Optical memory accessing and tracking apparatus with pickup and lens

A beam tracking system is used in an optical information recording and/or reproducing apparatus to optically track a record medium track. An objective lens irradiates an optical beam onto the record medium and is driven by a lens actuator to sweep the optical beam in a coarse mode relative to a predetermined track of the record medium. A carriage moves relative to the record medium for carrying the objective lens thereon and is driven by a carriage actuator to sweep the optical beam in a fine mode relative to the track. A detector detects the reflected optical beam during the sweep of the optical beam to produce a tracking signal representative of the deviation of the optical beam from the track. A pair of control circuits are connected to control the lens and carriage actuators respectively to effect the alignment of the optical beam with the track according to the tracking signal. A timing circuit is coneected to enable operation of the control circuit which controls the lens actuator and to inhibit operation of the other control circuit which controls the carriage actuator for a certain interval to effect alignment of the optical beam solely by means of the lens actuator, and thereafter to enable the other control circuit to maintain the optical beam alignment by means of the cooperative action of the lens and carriage actuators.

Optical beam tracking system for use in optical information recording

Apparatus for compensating for physical deviations due to warp and surface deflections in optical discs during optical recording and reproducing operations. Focus error signals are developed corresponding to the individual addresses of the physical deviations and the extent of deviation from the in-focus position of the focusing lens by moving a light pickup under control of a microcomputer radially of the disc so that N given radial pitch intervals are defined relative to the record surface of the optical discs and M circumferential address positions of each rotation of the disc. The detector detects the focus error signal values at M.sub.x N.sub.x address locations which are memorized in a memory storing M.times.N values and these are used for developing control signals for moving a focusing lens vertically with an actuator activated by the control signals so that the position of the focusing lens vertically is positioned relative to the record surface so that the focus distance to the record surface is compensated for the physical deviations and an in-focus condition obtained. An arithmetic unit develops light intensity correction values from the memorized data and from this power correction values signals are applied to the source of light beam so that the light beam is applied to the record surface as a spot of proper area dimensions and intensity compensated for the physical deviations.

Servo apparatus for compensating for warp and deflection deviations on

In an auto-focussing system, an actuator which moves together with an objective lens is vertically movable against a rotating optical disc and radiates a light beam so as to form a light spot on an information plane of the disc. A focus servo unit moves the actuator so that an optical distance between the actuator and the disc is within a proper distance region and performs the focus control of the light spot on the disc. While the actuator is approaching the optical disc, an auto-focus/focus servo controller initially makes the servo unit nonoperative and, when the actuator reaches a too-far position in a suitable servo loop distance region specified by a servo loop of the focus servo unit, the controller temporarily stops the movement of the actuator and then moves the actuator again from the too-far position by only a predetermined distance, thereby causing the actuator to be located within the focus loop distance region.

Microprocessor controlled focussing servo acquisition

The invention relates to a method and an apparatus for generating a data recording area signal in order to define an appointed data recording area on a data storing medium which has a multitude of sectors with high information density recorded by means of beam irradiation. The index signal derived from the detected index pattern in a sector is used together with a clock signal supplied.

Data recording area signal generating method and apparatus

A head drive control apparatus has a head and a scale reader. When the head is moved by a head drive mechanism, the scale reader detects the marks on a scale and converts them into a scale signal. In a speed control mode, the scale signal is compared with a target signal by an access signal generator, which produces an access signal representing the difference between the compared signals. The head is moved in accordance with the access signal until the scale signal becomes identical with the target signal. When these signals become equal, the speed control mode is switched to a position control mode. In the position control mode, a scale signal generator, a pulse generator, an up/down counter, a D/A converter, an adder and an interpolator convert the scale signal into an analog signal which represents the position of the head. The analog signal is compared with a position designating signal by a differential amplifier. The head is moved in accordance with the output signal of this amplifier.

Head drive control apparatus

A detecting circuit for detecting an operating center of an actuator of an optical head includes a first comparator for comparing a tracking signal based on a reproduced signal coming from the optical head with a reference voltage approximate to zero voltage level, and a second comparator for comparing the tracking signal of which the DC component is removed with a second reference voltage approximate to zero voltage level. A level inversion of a binary output signal of the first comparator is detected at a level inverting point of a binary output signal of the second comparator. The operating center of the actuator is checked with the detection of the level inversion.

Actuator operating center detecting circuit and optical disk apparatus

An optical disk apparatus has an optical disk for recording data into a recording area on an optical disk and reproducing the recorded data from the recording area. The optical disk is provided at the center with a first section with the same reflectivity as that of the recording area and a second section with a different reflectivity from that of the recording area. A photosensor sense detects the first section and produces a signal representing a reflectivity on the first section. The reflectivity data obtained from the signal level is used for controlling a gain of the servo system according to the reflectivity data.

Optical disk apparatus

A checking system for checking defects on an optically flat surface of an object to be checked is adapted to spirally scan the surface of the object with a laser beam which is projected from an optical head. The laser beam is reflected from the surface of the object and converted by a photodetector to an electric signal. The level of the electric signal is compared with a reference level to produce a defect signal. The rotation of the object is detected by a position sensor. A counter counts a position signal in response to the defect signal and the contents of the counter is stored, as data representing a defect start position, in a defect position memory. The length data of the defect signal is counted and stored in a defect length memory. Predetermined defect position data is read out of a defect position memory, while defect length data corresponding to the defect position data is read out of the defect length memory. Position data associated with an area to be displayed is compared with defect position data. When both data coincide with each other, the corresponding defect length data is counted down. During the down count period, defect picture element data is stored in a refresh memory. The picture element data stored in the refresh memory is delivered to a CRT where it is displayed as defect data.

System for checking defects on a flat surface of an object

In a system for detecting defects on an optical surface, a disk to be inspected is mounted on a turntable, and is attracted on the surface of the turntable. On the disk is provided an optical head having an objective lens located at its focal point on the surface of the disk. A laser beam emitted from a laser unit is projected through the optical head onto the disk, is reflected on the disk, and is then directed through the optical head to a photo detector. The optical head is moved in the radial direction of the disk as the turntable is rotated, and the disk is helically scanned by the laser beam. Only a defect signal is extracted from an electrical signal generated from the photo detector in a defect signal generator. The defect signal is compared in a data processing unit, and is converted to defect information of different size. When it is judged that a prescribed region on the surface of the disk is scanned by a position signal from a position sensor for detecting the position of the optical head, the data processing unit generates an address, and the defect information is stored in each size in specific assigned locations of the RAM. The defect information thus stored is displayed on a CRT or is printed out by a printer.

System for detecting defects on an optical surface

A disc drive apparatus for driving a disc selected from discs of various diameters with and without a central hole comprises: a turntable with a hole at the center of rotation thereof; a turntable support for rotatably supporting the turntable; a motor for driving the turntable; a centering member to be detachably inserted in the hole of the turntable and for mounting a disc with a central hole; a plurality of elastic disc support members which are coaxial with the center of rotation of the turntable, which extend from the surface of the turntable, and which form a plurality of annular shapes; centering index marks, disposed on the turntable, for centering a disc without a central hole; a vacuum pump; and suction channels, one end of which is open to the surface of the turntable and the other end of which is connected to the vacuum pump, for fixing on some of the disc support members the disc selected from discs of various diameters with and without a central hole and placed on some of said disc support members.

Disc drive apparatus

A system for focusing an optical head onto a flat surface has a mechanism for moving the optical head in the direction of the optical axis of the head and a mechanism for moving an objective lens in the optical head in the direction of the optical axis of the lens. A laser beam projected from the objective lens of the optical head is reflected on the flat surface, is reflected on the beam splitter, and is introduced into a detector unit. The detector unit thus generates a focusing signal having a level responsive to the distance between the objective lens and the surface. The optical head is lowered by the mechanism for moving the optical head in accordance with the focusing signal when it passes a predetermined point, and is operated to locate the focal point of the objective lens on the surface. Thereafter, the mechanism for moving the optical head becomes inoperative, and the mechanism for moving the objective lens is operated. This mechanism operates in accordance with the focusing signal and locates the focal point of the objective lens always on the surface.

System for focusing an optical head onto a flat surface

This invention is for a tape cassette having window for insertion of a magnetic head and a pinch roller formed extending from a peripheral wall of the housing of the tape cassette to one of the holding plates which holds a pair of reel hubs in place. The device according to this invention has a shutter member, and a resilient metal wire housed in the housing. The shutter member has projections which are to be engaged with an engaging member provided on a tape cassette holder member of the magnetic tape transport apparatus. The metal wire urges the shutter member to close a portion of the window formed in the holding plate. When the cassette is loaded into the loading member, the projections engage with the engaging member and the shutter member releases the closing state of the holding plate forming portion of the window against an urging force of the wire. When the cassette is removed from the loading member, the shutter member closes the holding plate forming portion to prevent the tape from being damaged by an external force.

Magnetic record tape protective device for a tape cassette

First and second capstans are rotated at respective speeds by first and second motors. The speeds of revolution of the first and second motors are detected as detection signals, and the revolution speed of at least one of the first and second motors is controlled in accordance with a difference between the detection signals. An offset voltage is added to one of the detection signals corresponding to the revolution speeds of the first and second motors for the control of tape tension.

Double-capstan tape driving device

A tape cassette according to this invention comprises at least three guide rollers disposed inside the housing of the tape cassette. The at least three guide rollers define a position of the magnetic recording tape of the tape cassette relative to the housing across the thickness thereof while the tape is travelling from one of two reel hubs held by the housing along a path extending adjacent a front wall of the housing, the front wall having openings for the insertion of a magnetic head and a pinch roller.

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Tokyo, Japan

Ken Ohshima