Nippon Conlux Co., Ltd.

Nippon Hoso' Kyokai

Murata Kikai Kabushiki Kaisha

Kabushiki Kaisha Nippon Coinco

Nippon Conlux, Ltd.

Koichi Yamazaki

Kazuo Noda

Eiichi Nakamura

Akira Onodera

Osamu Yamada

Yasuyuki Kimura

Toru Kuroda

Masayuki Takada

Hiroaki Yoshida

Tetsuya Honda

Yonezo Furuya

Kenzou Yoshihara

Keijirou Fujino

A laser light beam generated from a light source is divided by a diffraction grating into a plurality of light beams, i.e., a single main beam to be used for recording information and plural auxiliary beams distributed on two imaginary straight lines crossing each other. One of the straight lines extends parallel to tracks of a recording medium. The resultant divided beams are converged to be irradiated onto a recording medium, and reflected components, from the recording medium, of the beams are received by corresponding light receiving elements. Thus, the main and auxiliary beams distributed on one of the two imaginary straight lines are used to perform focusing and tracking. Further, one of the two auxiliary beams distributed on the other straight line are used to determine whether a track where information is to be recorded is a blank area or not, and the other of the auxiliary beams is used to verify whether the information has been recorded correctly.

Optical information recording device and method for detecting and

Each information recording track has pre-formatted fore and rear header sections containing address information identifying the track, which permit each of the recording tracks to be accessed from either of the header sections. A predetermined synchronization signal is pre-formatted in a storing area for each frame having a predetermined data size, so that information can be non-rewritably recorded onto the storing area for a predetermined frame by referring to the pre-formatted synchronization signal. With this arrangement, data can be recorded onto a selected information recording track in either of the directions of relative reciprocating movement of the recording medium to a recording/reproducing head, and thus the recording speed can be increased. The arrangement also allows data to be recorded even when one of the header sections has become unreadable due to some defect of the recording medium, and prevents occurrence of jitters in reproduced signals by allowing data to be recorded accurately at predetermined locations for each of the frames.

Optical information recording with preformatted synchronization signals

In an optical information recording and reproducing apparatus, information is recorded or reproduced by moving a recording medium relative to an optical head. In order to execute information recording onto the medium in the course of the relative movement involving acceleration and deceleration, the generation timing and intensity of a light beam to be generated in correspondence with the information to be recorded are controlled in response to a varying speed of the relative movement so that data pits to be formed in the recording medium can be standardized in pitch and size irrespective of the relative movement speed. Also, in order to permit information reproduction from the medium in the course of the relative movement involving acceleration and deceleration, reproduction timing of data read by the optical head is set in synchronism with variation in the relative movement speed so that the data can be reproduced at proper timing irrespective of the relative movement speed. With such arrangements, there can be achieved a highly increased information recording/reproduction speed, extended information recording area, reduced size and cost of the apparatus, and reduced power consumption in the apparatus.

Method of and apparatus for recording and reproducing optical information

For recording or reproduction of information, the optical beam is moved relative to the recording medium along the longitudinal direction of a certain track. When accessing another track, the relative movement of the light beam along the longitudinal direction of the track is decelerated, and during this deceleration, the light beam is started to move in the direction transverse to the tracks toward the desired track. Thus, it is not necessary to wait for such time when the relative movement of the light beam along the longitudinal direction of the track has been completely stopped, and hence the necessary accessing time can substantially be reduced. If control is made to cause a decelerating rate of the relative movement to decrease continuously gradually or stepwise from a relatively high decelerating rate to a relatively low rate and the light beam is caused to start relatively moving toward the desired track while the relative movement is at the relatively low decelerating rate, it is allowed to effectively suppress occurrence of unwanted mechanical vibration due to abrupt deceleration of the relative movement.

Method and apparatus for accessing a target track on optical medium

In a laser output control device for use in an optical information recording and reproducing apparatus which uses output light from a semiconductor laser device to record and reproduce information onto and from an optical information recording medium, a light receiving element is provided on the peripheral portion of a laser light emitting window formed in a housing of the semiconductor laser device. The peripheral component of forward radiated light of the laser light output from the semiconductor laser device is received by the light receiving element, so as to control the output power of the semiconductor laser device in accordance with output of the light receiving element corresponding to the received light.

Laser output control device for an optical information recording and

Information is recorded and reproduced by making a light beam traverse guide tracks to reach a target track. In moving the light beam to the target track, a tracking error signal is supplied to the inverting input terminal of a comparator to compare it with a potential at the non-inverting input terminal. The comparator outputs a comparison result signal to an output terminal. This output signal is fed back to the non-inverting input terminal via a feedback element so that the potential at the non-inverting input terminal changes with the output signal of the comparator. With the operation of the potential control circuit, a large feedback signal of the feedback element is used when a tracking control off signal is supplied, so that the potential at the non-inverting input terminal is easy to change with the output signal level. When the tracking control off signal is not supplied, a small feedback signal is used to change the potential at the non-inverting input terminal with the output signal level. The signal detected by the comparator is supplied to the output circuit to reference the direction control signal and generate a track traverse detecting signal.

Information recording/reproducing apparatus for optical information

In an error correction circuit, when a data loss is detected, substitute data comprising all bits of '1' or '0' are generated during a data loss period and substituted for the lost data for the data loss period. Thereafter, the whole data containing the substitute data are decoded in a predetermined error correction system to generate corrected data.

Error correction circuit which substitutes bits into data stream during

In a tracking or focusing servo control loop, there are provided a switch element for switch-controlling a tracking or focusing error signal, and a smoothing circuit for switching passage the error signal. An amount of detected reflection from an optical recording medium is monitored by a controller section, and the switching action of the switch element is ON/OFF-controlled by the controller section so as to maintain a servo loop gain at a predetermined standard. Thus, it is possible to maintain a constant servo loop gain without being influenced by variation in the laser light amount or difference in reflectivity characteristics of the recording layers of individual optical recording media, and constantly stable tracking servo control and/or focusing servo control can be performed.

Optical recording and reproducing system using servo control, switches

A high-density recording medium has data tracks and guide tracks formed on both sides of each of the data tracks. Intervals between the guide tracks are set in such a manner that the outer edges of two adjacent guide tracks correspond in position to two tracking laser beam spots on the recording medium. To allow use of either of the high-density recording medium, and a conventional recording medium on which intervals between guide tracks are set in such a manner that the inner edges of two adjacent guide tracks correspond in position to two tracking laser beam spots, control is performed such that polarity of a tracking control servo is selectively inverted depending upon which of the high-density and conventional recording medium is used.

Tracking system for use in regular and high density optical recording

A position detector detects a relative position of an optical head to a recording medium, and on the basis of the thus-detected relative position, a position detection signal is generated in response to movement of a light beam over a predetermined distance. Then, in response to the position detection signal, a comparison is made between the number of track crossing counted for the predetermined movement distance on the basis of reception of reflection of the light beam, and a predetermined reference value for the predetermined movement distance. Then, track crossing count compensation data is generated which corresponds to a difference between the counted number of track crossing and the reference value, and the counted number of track crossing is corrected by use of such compensation data.

Track seek method and device for use with an optical information

An information storage and retrieval device comprising a card conveyor mount for supporting and conveying a card-type information storage medium; a drive means having a linear motor, for reciprocatingly driving the card conveyor mount; an electrical power control circuit having switching elements, for providing power to the linear motor; speed detection means and for detecting the speed at which the card conveyor mount is moving. A speed command for calculating an indicated speed corresponding to an output from the speed detection means, shaping a speed command therefrom, and sending the command to the electrical power control circuit; and an optical head for irradiating a laser beam onto the information storage medium; whereby information is written to the information storage medium by the optical head irradiating the laser beam onto the information storage medium, and information is read therefrom by detecting laser light reflected from the information storage medium; the information storage and retrieval device further comprising a comparison means having a pair of comparators and having identical threshold values of different polarities.

Information storage and retrieval device

Information is recorded and reproduced by making a light beam traverse guide tracks to reach a target track. In moving the light beam to the target track, a current output circuit responds to a track jump command, and supplies a drive current to an objective lens driver. The driver current is transformed by the conversion circuit into a rapidly rising and gradually falling current, and supplied to the driver, The objective lens then moves. When the light beam reaches a track adjacent the target track, a track traverse detecting circuit supplies a track traverse detecting signal. In response to this signal, the current output circuit supplies a damping current by reversing the polarity of the drive current to the driver. The damping current is transformed by the conversion circuit into a rapidly rising and gradually falling current, and supplied to the driver.

A write once type information recording medium having a recording format that includes sectors. Each Sector includes x pieces of p-bit frames. Each frame contains an f-bit synchronization signal region and a d-bit data region. Each bit of at least one x-bit packet in which a v-bit error correction code has been added to u-bit data, is distributed to each one of the data regions of the x pieces of frames. This makes it possible for the write once type information recording medium to have an increased data storage efficiency and an effective error correction capability for a burst error.

Write once type information recording medium, method and apparatus for

An optical information recording and reproduction apparatus that correctly performs tracking control even when there is a step in the information recording surface in an apparatus that records and reproduces information to and from an information recording medium such as an optical card or the like. An optical information recording and reproduction apparatus which focusses a light spot from a laser onto an optical information recording medium which has a tracking track and performs the recording and reproduction of information to required positions using the tracking track as a reference. The apparatus reduces the optical output of the laser when track jumping and seeking when there is an information reproduction operation.

Optical recording/reproducing by reducing laser power when there is a

The present invention provides an optical card wherein the irradiation position of laser beams is pulled back into an information recording section 1 in such a manner that the operation of recording or reproducing information can continue. In this optical card, information is recorded on or reproduced from a prescribed information recording section on a card surface in accordance with optical scanning along guide tracks provided in the card surface, and the optical card is provided with a mirror section arranged adjacent to the information recording section in the direction parallel to the direction of optical scanning of the information recording section. The optical card is characterized in that the mirror section is provided with at least one pair of curved auxiliary guide tracks that are connected to the guide tracks in the information recording section.

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Sakado, Japan

Koichi Yamazaki