Abstract: The optical disk of this invention includes a read-only area in which a plurality of read-only tracks are formed and a rewritable area in which a plurality of rewritable tracks are formed, wherein each of the plurality of read-only tracks is divided into a plurality of first sectors, a signal is prerecorded in at least one of the plurality of first sectors under a predetermined reproduction format, each of the plurality of rewritable tracks is divided into a plurality of second sectors, a signal is recordable in at least one of the plurality of second sectors under a predetermined recording format including the predetermined reproduction format, and the read-only area is located on an inner portion of the optical disk, while the rewritable area is located on an outer portion of the optical disk.

Abstract: Provided is a process for producing an ethylenimine polymer aqueous solution which has a high concentration (high resin content) and is less changeable with the passage of time, that is, has a stabilized quality. The above process comprises polymerizing ethylenimine in a water based medium at a temperature of 80° C. or lower and then ripening it at a temperature of 100 to 150° C.

Abstract: In a recording and reproducing apparatus for a disc-shaped recording medium, and a defect substitution method for a disc-shaped recording medium (8), whether reproduction of recorded data is good is determined by sector unit and not by product code unit, defective sector discrimination is performed by sector unit, and only sectors determined defective are alternately recorded, when using a recording format in which data that is error detection and correction coded with a product code is segmented and recorded to a plurality of sectors.

Abstract: In a recording and reproducing apparatus for a disc-shaped recording medium, and a defect substitution method for a disc-shaped recording medium (8), whether reproduction of recorded data is good is determined by sector unit and not by product code unit, defective sector discrimination is performed by sector unit, and only sectors determined defective are alternately recorded, when using a recording format in which data that is error detection and correction coded with a product code is segmented and recorded to a plurality of sectors.

Abstract: Provided are processes by which an ethylenimine polymer and an aqueous solution thereof can advantageously be produced at low costs in an industrial scale. The ethylenimine polymer can be produced by polymerizing crude ethylenimine obtained by a simple distilling operation from an ethylenimine-containing reaction mixture produced by subjecting ethanolamine to intermolecular dehydration reaction, preferably crude ethylenimine having impurity contents which are controlled in the specific ranges. When the above crude ethylenimine is polymerized in an aqueous medium, capable of being obtained is an aqueous solution of an ethylenimine polymer having a higher molecular weight than that produced by non-solvent polymerization. The ethylenimine polymer can be purified by, for example, adding water thereto, mixing them and then vaporizing and removing water under heating. The aqueous solution of an ethylenimine polymer can be purified by heating and condensing it.

Abstract: In a recording and reproducing apparatus for a disc-shaped recording medium, and a defect substitution method for a disc-shaped recording medium (8), whether reproduction of recorded data is good is determined by sector unit and not by product code unit, defective sector discrimination is performed by sector unit, and only sectors determined defective are alternately recorded, when using a recording format in which data that is error detection and correction coded with a product code is segmented and recorded to a plurality of sectors.

Abstract: One or more optical discs, each having a ROM field having information with a length of at least one track formed in convex and concave pit rows, and a rewritable field capable of rewriting the information with a length of at least one track, an information unrecorded field having a length of at least one track located between the ROM field and rewritable field, the rewritable field having a spiral or concentric guide track oscillating in a radial direction, the ROM field having spiral or concentric convex and concave pit rows, and at least a part field at the rewritable field side of the information unrecorded field has a transition field having a spiral or concentric guide track oscillating in the radial direction continuously or intermittently and a track pitch To of the ROM field and a track pitch Tw between grooves and lands of the rewritable field have values such that To>Tw.

Abstract: An information recording method has;a history determination step for determining whether or not a medium being cased and capable of being used for information recording and reproduction has previously been taken out from the case by using an identification section having historical information as to whether the medium has previously been taken out from the case or not; anda verification step for verifying correctness of information recorded always or on condition that a predetermined condition is satisfied when a result of the determination shows that the medium has previously been taken out from the case.

Abstract: In an optical disc, an ID field contains a plurality of address information, and is preliminarily recorded in convex and concave signals, and is composed of two sets offset by about 1/2 track pitch toward the internal or external track direction adjacent to the guide track, an information recording field is composed of grooves and lands oscillating at a single frequency in the radial direction, and the grooves and lands alternate in every revolution of the guide track. When w bits of information are included in one period of oscillation, an information unrecorded field between the ID field and information recording field is arranged to have a length of w/10 bits or more and/or w bits or less, and therefore, when recording continuous information data such as video data, it is possible to record continuously by generating a clock securely from the oscillating signal, and moreover, the format efficiency is improved, so that a format of a larger capacity is achieved.

Abstract: In a recording and reproducing apparatus for a disc-shaped recording medium, and a defect substitution method for a disc-shaped recording medium, whether reproduction of recorded data is good is determined by sector unit and not by product code unit, defective sector discrimination is performed by sector unit, and only sectors determined defective are alternately recorded, when using a recording format in which data that is error detection and correction coded with a product code is segmented and recorded to a plurality of sectors.

Abstract: An information recording/reproducing apparatus and a method of recording data onto an information recording/reproducing media. The information recording/reproducing apparatus has the capability of handling the information recording/reproducing media both when they are not in the case and when they are in the case. A recording mode is selected basing on the determinations of (i) whether or not the recording/reproducing medium is a medium type which is necessarily contained in a case at recording and (ii) whether the case is presence or absence. The recording mode is selected among (i) record information onto the information recording/reproducing medium, (ii) perform after-defect-inspection recording or defect-inspecting after recording, and (iii) inhibit recording of information.

Abstract: An optical disk includes a read-only area in which a plurality of read-only tracks are formed and a rewritable area in which a plurality of rewritable tracks are formed, wherein each of the plurality of read-only tracks is divided into a plurality of first sectors, a signal is prerecorded in at least one of the plurality of first sectors under a predetermined reproduction format, each of the plurality of rewritable tracks is divided into a plurality of second sectors, a signal is recordable in at least one of the plurality of second sectors under a predetermined recording format including the predetermined reproduction format, and the read-only area is located on an inner portion of the optical disk, while the rewritable area is located on an outer portion of the optical disk.

Abstract: In an optical disk having a recording plane having a spiral first track and a spiral second track, information being to be recorded into and/or reproduced from said first and second tracks, the first track is formed into a groove-like shape, the second track is formed between adjacent the first tracks and into a land-like shape, and the first and second tracks record informations in different modulation methods.

Abstract: In an optical disk having a recording plane having a spiral first track and a spiral second track, information being to be recorded into and/or reproduced from said first and second tracks, the first track is formed into a groove-like shape, the second track is formed between adjacent the first tracks and into a land-like shape, and the first and second tracks record informations in different modulation methods.

Abstract: An optical disc using a single-spiral land and groove track format enabling accurate tracking offset correction and reliable detection of the transition point between a land track and a groove track, and a driving apparatus therefor. Four physical address areas PID1, PID2, PID3, and PID4 are recorded to a header area such that PID1 and PID2 are offset one-half track pitch toward the outside circumference of the disc from the groove track center, and PID3 and PID4 are offset one-half track pitch toward the inside circumference of the disc from the groove track center, and the physical address areas PID1-PID4 can be detected by means of a difference signal in the radial direction. The single frequency pattern area VFO at the beginning of each PID is lengthened by PID1 and PID3, thereby enabling tracking offset correction using a sum signal, and detection of the land-groove transition point using a difference signal obtained from the PID offset.

Abstract: An optical disc having both rewritable area and read-only area is disclosed. The rewritable area has a single spiral pattern of start track land at a leading edge, and a single spiral pattern of end track land at a trailing edge, whereby portions of the physical address area PID deviated approximately Pa/2 from the track of the rewritable area are being intruded into the start track land and the end track land.

Abstract: In an optical disk having a recording plane having a spiral first track and a spiral second track, information being to be recorded into and/or reproduced from said first and second tracks, the first track is formed into a groove-like shape, the second track is formed between adjacent the first tracks and into a land-like shape, and the first and second tracks record informations in different modulation methods.

Abstract: A multi-layered optical disk comprising a plurality of recording layers accumulated in the thickness direction wherein a light beam is focused on one of tracks of one of the layers thereby to record and reproduce data, the optical disk being characterized in that recording layers each have an identification section storing an address of the recording layer which the identification section belongs to.

Abstract: In an optical disk having a recording plane having a spiral first track and a spiral second track, information being to be recorded into and/or reproduced from said first and second tracks, the first track is formed into a groove-like shape, the second track is formed between adjacent the first tracks and into a land-like shape, and the first and second tracks record informations in different modulation methods.

Abstract: In an optical disc recording-reproducing apparatus using a standard optical disc enclosed in a cartridge, and optical plate for correcting various aberrations generated by a focusing lens is comprised therein in order to allow use of a double recording optical disc enclosed in the standard cartridge of the same size, the optical plate is placed in front of a focusing lens when the double recording optical disc is used, and is removed from the front of the focusing lens when the standard optical disc is used.