Abstract: An information recording and reproducing apparatus detects deterioration in a recording medium. Structure is provided for recording information including an error correction code. A signal indicative of recorded information is received, and an error signal indicative of a number of errors that are detected is produced. This error signal is based on verification of the error correction code. The error correction code is verified using a strict clipping level, which is a level stricter than a usual level recognized as a particular signal level. This strict clipping level is compared with the signal indicative of reading areas, and error signals are produced thereby. When the error signal indicates a number of errors greater than a predetermined number, each sector is checked to determine if it is a bad sector. Each bad sector is recorded with a mark signal that indicates a bad sector.

Abstract: This invention relates to an optical disk, in which part of the sectors are reproduction-only sectors and remaining sectors are recording-reproduction sectors. Data and first error correcting codes for the data are recorded in advance in the reproduction-only sectors, and second error correcting codes for data over a plurality of reproduction-only sectors are recorded in advance in other reproduction-only sectors. At data reproduction, only sectors which are unrecoverable by the first error correction codes undergo error correction by the second error correcting codes, and the corrected data with the first error correcting codes being appended are recorded in the recording-reproduction sectors. Later on, when data in sectors unrecoverable by the first error correcting codes are needed, the above-mentioned recorded sectors are read out.

Abstract: An information recording and reproducing apparatus records and reproduces information on and from an optical recording disk having a sector recording format of frame structure in which data in each sector are divided into a plurality of frames, and a data head identification mark is affixed to the head of each of the frames, so as to prevent propagation of a demodulation error due to failure of word synchronization attributable to pull-out of a PLL during data reproduction. In the apparatus, one frame pulse is generated for each of the frames on the basis of a sector identifier detection signal and a frame data demodulation start signal, and, according to the result of counting the frame pulses, the frame numbers of frame data demodulated and stored in a sector buffer memory are accurately detected.

Abstract: A data recording and reproducing apparatus is disclosed in which an optical disc for recording, reproducing or erasing data is radiated with an erasing light beam and a recording-reproducing light beam sequentially to record or reproduce the data with the recording-reproducing light beam and erase the data with the erasing light beam. In rewriting the data, the erasing light beam is radiated in advance of the recording-reproducing light beam on a data section of the disc, and the old data is erased by temperature increase and annealing by the erasing light beam, while new data is recorded by temperature increase and quenching with the recording-reproducing light beam set to the recording light intensity. After recording the new data, the light intensity of the erasing light beam is gradually decreased and turned off.

Abstract: In an information and recording and reproducing apparatus using a disc-shaped information recording medium having a plurality of recording tracks, each of which recording tracks is divided into a plurality of sectors, to record and reproduce information on and from the information recording medium on a sector-by-sector basis, when a target sector is detected to be a defective sector whose address can not be reproduced, in the first place, a reference sector, which is positioned preceding the defective target sector and whose address can be reproduced, is detected.

Abstract: An optical disk exclusively used for reproduction has an optically detectable guide groove in which signals have previously been recorded. One type of optical disk exclusively used for reproduction is interchangeable with an optical disk which allows both recording and reproducing operations or enables information recorded thereon to be erased. If such an optical disk is not provided with a guide groove in an unrecorded region remaining between a data managing information region and a data recording region, problems may arise when the optical head of an optical disk apparatus is positioned in the unrecorded region at the time of starting the operation of the apparatus and when the optical head effects retrieval between the data managing information region and the data recording region.

Abstract: In an optical information recording/reproducing apparatus for recording/reproducing information on or from an optical disc, a laser beam is focused on the surface of a substrate of the optical disc so that the intensity or a high frequency component of a reflected laser beam is used to detect contaminants on the optical disc surface or a test signal containing a plurality frequency components and recorded on a specified track on the optical disc is reproduced and detected so that the difference between amplitudes of the frequency components is used to detect contaminants on the optical disc surface. Scattering of the laser beam can be prevented and recording/reproducing can be effected with a proper level of laser power.

Abstract: An information recording and reproduction apparatus for recording and reproduction of information in a recording medium having an information recording area divided into a plurality of sectors, in which a defective sector is replaced for recording and a signal for identifying the defective sector is recorded. Each sector includes a preformatted sector identification section ID and a data field for recording data therein. A defective sector is replaced by a sector at another position. When the sector identification section ID and/or data field DF has a defect, a first signal is recorded in addition to the data in the data field DF, followed by writing a second signal overlapped in the sector identification section ID of the same sector which causes an address data read error thereby to attach a defect mark to the defective sector.

Abstract: An optical recording and reproducing apparatus for recording and reproducing data in an optical disk is disclosed. The optical disk has a plurality of erase test sectors in tracks, in one of which the accumulated number of tests together with test data is written. The data read from the erase test sector is compared with the recorded data to effect an erase function diagnosis. If data comparison shows an non-coincidence or the accumulated number of tests exceeds a predetermined value, a new erase test sector is used. The fatigue of the recording medium caused by a defect of the medium or reduced erasing efficiency due to an increased number of erasures of the recording medium is checked by controlling the accumulated number, completely separately from the fault of erase function of the apparatus, thus improving the reliability of the erase function self-diagnosis.

Abstract: An optical information recording and reproducing apparatus for recording and reproducing information on and from an optical recording disk having an optically detectable guide track divided into a plurality of sectors is disclosed. When a sector to or from which a data is to be recorded or reproduced is a defective sector or a non-use sector because of updating, a special pattern signal is recorded on the defective sector or the non-use sector, and if the recorded special pattern signal is detected in the reproduction cycle, that sector is determined as a defective or non-use sector and recording or reproducing on or from that sector is inhibited.

Abstract: A track skipping detection and control arrangement for an optical recording and reproducing disc formed with guide tracks for use in an optical information recording and reproducing apparatus. According to the track skipping detection and control arrangement of the present invention, any sudden track skipping which may take place during recording can be instantaneously detected by the track traversing signal so as to reduce the recording power for the prevention of erroneous recording to neighboring tracks. Moreover, by distinguishing the track traversing signal detected during the jumping operation for repeated continuous reproduction of the particular one track of the optical disc having spiral tracks, from the traversing signal due to the track skipping, erroneous recording may be similarly prevented also with respect to the optical disc having the tracks in the spiral configuration.

Abstract: In an interleaving circuit, writing and reading are executed on the two dimonsional array memory according to a first address sequence and a second address sequence, and product code errors occurring on the same column are propagated to the columns which are different with each other. The errors are thereby scattered to minimize the decreasing of the error correcting capability of the product codes.

Abstract: An optical information recording and reproducing apparatus for recording and reproducing information from an optical recording disc including an optically detectable guide track preliminarily divided into a plurality of sectors. In the case of an unerasable disc, if an uncorrectable error exists in any sector after data has been recorded and reproduced from the sector, it is necessary to process this sector so as to prevent further reproduction an again record the data in another sector. Also, when updating a part of the data or erasing the file, it is desirable to take a measure so that reproduction of the data in any unwanted sector is prevented. Also, in the case of any unrecorded sector involving such dropout that the recording of data is presumed to cause an uncorrectable error, it is desirable to handle it as a defective sector and process it so as to prevent the recording of data therein. In such a case, it is desirable to effect the similar process also in the case of an erasable disc.

Abstract: An optical disk for optical recording and reproducing data has a spiral track and further includes a single index field and a plurality of sectors. The index field includes an index mark that indicates the position at which an optical head of the optical recording and reproducing apparatus retraces a spiral track by jumping a specific portion of the guide track. Each of the sectors has a sector header, which comprises a sector mark located at the start of the sector and an address field including a track address, sector address, and an error detecting and correcting code. The index mark in the field is detected, and the optical head is made to perform a jumping operation in response to the resulting signal, whereby the jumping operation is rendered certain. When there is a failure to read the address fields, the signal produced by detecting the index mark starts a counter which counts the signal produced by detecting a sector mark, for recovering the sector address.

Abstract: An information recording and reproducing apparatus records and reproduces information in and from a recording medium including an information recording region divided into a plurality of sectors. In recording and reproducing information in and from the recording medium, each sector includes a sector address part formatted and a data recording part for recording data. A predetermined signal is overwritten in the address of a sector thereby making reproduction of the address impossible to prevent data from being recorded again by error in the sector containing data, while at the same time protecting the writing in the sectors.

Abstract: A light beam emitted from a semiconductor laser passes through optical elements which include a condenser lens, a magnifier prism, and a focussing lens to obtain a substantially circular spot of light on a disc. The magnifier prism is constructed such that only the narrower cross-section of the elliptical light beam emitted from the condenser lens is magnified by the incidence surface of the magnifier prism to obtain a substantially circular light beam. The light beam thus obtained is reflected by the prism so that it becomes substantially perpendicular to the beam emitted from the condenser lens. After reflection by the disc, the light passes through a splitter prism. The splitter prism has a reflecting surface and a transmitting surface which spatially bisect the light beam reflected from the disc, a lens and other components. The bisected portions of the beam fall on a photodetector for focussing control and a photodetector for tracking control.

Abstract: An optical recording and reproducing apparatus in which a laser beam is converged to a tiny beam spot and projected onto an optical disc to change thermally the optical disc, thereby effecting recording and reproducing of a signal and which detects a mark (17) for determining a recording polarity of the optical disc which is provided on an optical disc or a disc jacket and effects switching between analog gate switches (23a), (23b) in accordance with the result of the detection thereby to control a polarity of a signal to be recorded or reproduced in a positive or negative direction, whereby it is made possible to stably effect recording and reproduction of signals on optical discs which provide reproduced signals of different polarities because of the characteristics of their recording materials, such as erasable optical discs and unerasable optical discs, by using one and the same recording and reproducing apparatus.

Abstract: Apparatus for detecting and correcting errors on product codes, utilizing a product code of minimum distance 2t symbols constituted by two codes having minimum distance 2 and minimum distance t respectively. First the code of minimum distance t is decoded, and secondly error number flags generated in the decoding operation are classified into three decoding modes by statistical processing. Errors are detected or corrected according to the decoding mode.

Abstract: A data recording/reproducing apparatus which uses a recording medium having a data recording area divided into a plurality of sectors, each sector having an address section in which a first address signal is recorded and a data recording section, wherein a second address signal is added to data to be recorded, the second address signal representing an address of a sector in which the data is to be recorded, the data combined with the second address signal is encoded for error compensation and is recorded in the recording mode, and the second address signal reproduced with the data from the data recording section in the reproduction mode is used to discriminate an address of a target sector for reproduction. The sector address is obtained with the same level of precision as that of the reproduced data, thereby performing precise sector control and preventing data loss.

Abstract: An optical and reversible recording and reproducing apparatus providing a practical apparatus in which information signals can be recorded, reproduced and erased by irradiating a laser beam and the like on the substrate to be optically recorded. More practically, there is provided such an apparatus wherein two light sources such as lasers having different wavelengths are used, and a first almost circular micro-lightspot is produced by one light source, while a second elliptic light spot having a longitudinal diameter in the tangential direction of a guide track on a disc is produced by the other light source. These first and second light spots are closely irradiated on one and the same guide track of an optical recording disc. The recording and reproducing of the signals are performed using the first light spot while the erasure of the recorded signals can be made by using the second light spot or using both first and second light spots in combination.