Abstract: An optical disk recording, and reproducing apparatus for recording and reproducing information and which is capable of storing a large amount of information, transferring data at a high speed, and supporting SCSI-1 and SCSI-2. The magnetooptical-disk recording and reproducing apparatus is of the same size as that of the 5.25-inch magnetic disk recording and reproducing apparatus. The front panel 1 has the cartridge slot 2 and cartridge ejection button 3 provided thereon so that a cartridge including a disk for recording and reproducing information is inserted in or ejected from the apparatus. The cartridge insertion slot 2 has a double flap provided so that at least one part of the double flap closes the slot, preventing dust from entering through the cartridge slot 2 except when the cartridge is inserted in or ejected from the apparatus. The magnetooptical-disk recording and reproducing apparatus can record information of 1 GB/side or above on the disk.

Abstract: An optical method for recording, reproducing, and erasing a digital signal of a mark length recording system onto/from an optical recording medium such as an optical disc or the like eliminates a fluctuation of the edge position of the reproduction signal due to heat interference between pits, thereby reducing a fluctuation of the edge position due to a fluctuation of external environmental conditions. For this purpose, there are proposed the following methods: 1) the shape of the recording pulse waveform is controlled, 2) the density at which data is recorded to the disc is variably set in accordance with the disc position, 3) a test recording is executed prior to recording user data, and the like. With these methods, a superhigh density optical recording can be realized.

Abstract: In a write control method on an optical recording, at least one shift amount selected from the defocus amount of a laser beam on a recording medium, the shift amount of a recording position on a recording track and the shift amount of laser power during recording is controlled such that the selected amount falls within a predetermined range. Subsequently, a trial signal is trially recorded at a plurality of trial zones on the recording medium by using a laser power value as a parameter. The recorded trial signal is read and a difference .DELTA.V between center levels of a highest density waveform and a lowest density waveform is detected. In connection with each trial zone, the laser power value when a reading trial signal which makes the difference .DELTA.V minimum is recorded is defined as an optimum recording power value.

Abstract: An optical recording medium on which information is recorded by irradiating the medium with a light spot to cause a characteristic change of an actual reflection factor, the optical recording medium including grooves of different optical depths which extend in a direction in which the light spot is moved relative to the medium and which are alternately and periodically formed in a direction perpendicular to the relative movement direction of the light spot so that a plurality of grooves thereof can be covered by the light spot, and mark recording regions provided on the flat surfaces between the grooves, the pitch of the flat surfaces between the grooves being selected to be substantially half the diameter of the light spot, thus increasing the recording density and preventing the cross-talk. A method and apparatus for reproducing the information recorded on the medium are provided.

Abstract: An optical disk recording and reproducing apparatus for recording and reproducing information and which is capable of storing a large amount of information, transferring data at a high speed and supporting SCSI-1 and SCSI-2. The magnetooptical-disk recording and reproducing apparatus is of the same size as that of the 5.25-inch magnetic disk recording and reproducing apparatus. The front panel 1 has the cartridge slot 2 and cartridge ejection button 3 provided thereon so that a cartridge including a disk for recording and reproducing information is inserted in or ejected from the apparatus. The cartridge insertion slot 2 has a double flap provided so that at least one part of the double flap closes the slot, preventing dust from entering through the cartridge slot 2 except when the cartridge is inserted in or ejected from the apparatus. The magnetooptical-disk recording and reproducing apparatus can record information of 1 GB/side or above on the disk.

Abstract: An optical recording control method determines an optimum recording laser power by effecting a test recording before information to be recorded is recorded on a disk. The recording laser power is formed of a plurality of powers. A relationship among the plurality of laser powers is regulated by power level ratios between respective powers, whereby a power used when a laser light is radiated on the disk can be controlled to be constant independent of an ambient temperature and a structure of a disk. Therefore, accurate recording marks can be formed on the disk.

Abstract: A magneto-optical disk recording control method using the mark length recording method wherein the marks and gap regions between marks are recorded on the surface of the disk by maintaining a constant temperature distribution during the recording. The laser is driven to a non-recording level in gap regions between marks that exceed a base recording level used for reproduction of the marks. When a mark is recorded, the laser power is increased to a recording power level and after the mark has been recorded, the laser power level is reduced to the base power level, followed by being raised to the gap recording level. Control of the laser is performed by superposing a plurality of pulse trains that are synchronized with respect to a clock having a cycle T. The pulse trains are derived from the code train to be recorded and have pulses with a duration that is an integral multiple of (1/2)T.

Abstract: A MCAV optical disc read/write system with a postscript type of recording medium is, which uses a pit edge method of recording information in spiral physical tracks of the medium. The spiral physical tracks are grouped into logical tracks in which a single track address is assigned to each logical track. The logical tracks in turn are grouped into circumferential zones. The number of physical tracks constituting a logical track in adjacent circumferential zones, and the number of track sectors per logical track are set such that the increment in the number of sectors per physical track in proceeding from an inner one to an outer one of such zones is controlled to minimize rate changes in the read/write clock frequency at zone boundaries. Sector addresses thereby may be read even when a read/write head is positioned in a wrong one of adjacent zones.

Abstract: An optical disk recording and/or reproducing apparatus is provided which is capable of storing a large amount of information, transferring data at a high speed, supporting SCSI-1 and SCSI-2, and the reducing the size of the apparatus, particularly the height (to the so-called half height), The magnetooptical-disk recording and/or reproducing apparatus of the invention is of the same size as that of the 5.25-inch magnetic disk recording and/or reproducing apparatus of half height, or it is 146 mm wide, 203 mm deep, and 41.3 mm high. The front panel 1 has the cartridge slot 2 and cartridge ejection button 3 provided thereon so that a cartridge including a disk for recording and reproducing information is inserted in or ejected from the apparatus.

Abstract: An optical recording/reproducing apparatus includes a plurality of semiconductor lasers, an objective lens for focusing light beams from the semiconductor lasers on an optical disk to form a plurality of light spots, and a correction unit for reducing an offset in a tracking signal occurring concomitantly with relative position correction for the light spots. The correction unit includes a rotary wedge-shaped prism disposed in an optical path through which a laser beam incident on the optical disk and a reflection laser beam from a light spot on the disk pass in opposite directions. The shape, refractive index and initial installation angle of the wedge-shaped prism are designed to have predetermined values that cancel the position shift of the laser beam on the objective lens surface occurring concomitantly with deflection of the laser beam.

Abstract: An amplitude difference between a reproduction signal from a preformat portion of an optical disk and a reproduction signal from a recording portion of user's data is obtained. When the amplitude difference exceeds a predetermined value, a first gain value which was set for information from the preformat portion is used as a gain value of an AGC circuit for reproduction and a gain control of the reproduction signal is performed. On the other hand, when the amplitude difference is smaller than the predetermined value, a second gain value which was set for the user's data is used. Thus, a situation such that a noise and a remaining signal of the user's data which was not erased are erroneously recognized as an inherent reproduction signal can be prevented. A discrimination to see if the data has been recorded in the recording portion of the user's data or not can be also accurately performed.

Abstract: Disclosed is an optical recording and reproducing apparaus comprising a light source directing a light spot toward a recording medium, a detection system detecting light reflected from the recording medium to derive an electrical signal from the reflected light, an information processing circuit modulating the intensity of the light spot according to writing pulses to record information on the recording medium and using the electrical signal to reproduce information from the recording medium, and a tracking servo circuit carrying out tracking servo operation on the basis of the electrical signal and including an extracting circuit connected to a source of extracting pulses having a pulse width at least equal to the writing pulse width so that writing pulse parts contained in the electrical signal are extracted during recording information, whereby a track offset occurring during information recording can be minimized, and the stability of the tracking servo system can be improved.

Abstract: A record carrier having a disc-shaped substrate and a recording layer for optically writing information therein is disclosed which includes a guide groove extended in the rotational direction of the record carrier so that a plurality of revolutions of the guide groove are spaced apart from each other in radial directions of the record carrier, and a pit pattern provided between adjacent guide grooves, at positions arranged at intervals in the above rotational direction, for detecting the deviation of a light spot from the center line between adjacent guide grooves. The recording/reproducing operation for this record carrier is performed in such a manner that the first tracking error signal is detected from diffracted light from the guide groove, the second tracking error signal is detected from the pit pattern, and information is recorded in and reproduced from a land formed between adjacent guide grooves in a state that a tracking operation is performed using the first and second tracking error signals.

Abstract: In an information recording and reproducing apparatus for recording or reproducing information to/from tracks by irradiating a light spot to an optical disk in which N sectors are included per track and the number of necessary alternating sectors per track is set to M, the apparatus has a track format such that when a desired moving time of the light spot between the adjacent tracks is k times as long as a desired sector passing time of the light spot, M or more alterating sectors are arranged subsequent to the ordinary sectors to record user's data. The light spot jumps between the tracks for a period of time corresponding to k sectors. Thus, the recording of information to a certain track and the subsequent reading check (Read After Write) can be effectively executed at a high speed.

Abstract: An optical recording disc comprising a resin layer of resin material formed on a relatively rough surface of each transparent disc substrates, the resin material having approximately the same refractive index of light as the refractive index of the transparent disc substrate, and a recording layer formed on each of said resin layers. Accordingly, the optical recording disc enables a decrease in production costs and to write and read an information signal into and from the recording layer at an improved signal to noise ratio as compared to a conventional optical recording disc.

Abstract: A record carrier having a disc-shaped substrate and a recording layer for optically writing information therein is disclosed which includes a guide groove extended in the rotational direction of the record carrier so that a plurality of revolutions of the guide groove are spaced apart from each other in radial directions of the record carrier, and a pit pattern provided between adjacent guide grooves, at positions arranged at intervals in the above rotational direction, for detecting the deviation of a light spot from the center line between adjacent guide grooves. The recording/reproducing operation for this record carrier is performed in such a manner that the first tracking error signal is detected from diffracted light from the guide groove, the second tracking error signal is detected from the pit pattern, and information is recorded in and reproduced from a land formed between adjacent guide grooves in a state that a tracking operation is performed using the first and second tracking error signals.

Abstract: A magneto-optic memory apparatus is disclosed in which a laser beam is focused on a recording medium having a perpendicularly-magnetized film, the intensity of said laser beam is caused to correspond to reproducing, recording and erasing operations, an external magnetic field is applied to the recording medium at least in recording and erasing periods so that the magnetic field in the recording period is opposite in direction to the magnetic field in the erasing period, a light quantity signal corresponding to the light quantity reflected from the recording medium and a magnetization signal corresponding to data recorded on the recording medium are produced by using the reflected light from the recording medium, at least one of the light quantity signal and the magnetization is amplified by a variable gain amplifier so that an amplified value in the erasing period is nearly equal to an amplified value in the reproducing period, a defect on the recording medium is detected from the output of the variable gain

Abstract: 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.

Abstract: An optical memory apparatus employs an optical disc having a plurality of guide-grooves in spiral and concentrical form and a plurality of flat tracks each arranged between adjacent two of the guide-grooves for recording information thereon, and the depth of the guide-grooves is suitably selected to increase the degree of modulation of a track cross signal, thereby performing a stable cross track counting by the use of the track cross signal and a tracking signal. One feature of the invention relies in that the modulation degree of the track cross signal is in the range between 30 and 60%. A second feature of the invention is that the guide-grooves are formed into a V shape and have an optical depth of .lambda./6 to .lambda./5 (.lambda. is the wavelength of the light used).

Abstract: When recording domains are formed locally on a recording medium and information is recorded and reproduced by using rise and fall in a reproduced waveform obtained from the recording domains as data, timing patterns indicating start of demodulation are recorded for the lead-edge and the tail-edge of the recording domains, respectively; time interval between the timing signal for starting demodulation detected from the rise in the reproduced waveform and the timing signal for starting demodulation detected from the fall in the reproduced waveform is detected; time shifts of the signals detected from the lead-edge and the tail-edge of the recording domains succeeding the timing patterns for starting demodulation by using the time interval thus detected; and the information is stably detected as time sequential data having no jitter.