Source: https://patents.justia.com/patent/6449231
Timestamp: 2019-08-22 13:28:18
Document Index: 234383716

Matched Legal Cases: ['art 206', 'art 205', 'art 205', 'art 206', 'art 205', 'art 205', 'art 206', 'art 205', 'art 205', 'art 206', 'art 206', 'art 205', 'art 205', 'art 206', 'art 205', 'art 205', 'art 206', 'art 205', 'art 206', 'art 205', 'art 205', 'art 206', 'art 205', 'art 205', 'art 206', 'art 205', 'art 206', 'art 205', 'art 205', 'art 206', 'art 205', 'art 205', 'art 206', 'art 205']

US Patent for Storage unit, optical recording medium and information recording method Patent (Patent # 6,449,231 issued September 10, 2002) - Justia Patents Search
Justia Patents Of Record CarrierUS Patent for Storage unit, optical recording medium and information recording method Patent (Patent # 6,449,231)
Storage unit, optical recording medium and information recording method
Jan 19, 1999 - Fujitsu Limited
The intermediate layer 102 transfers or blacks the information recorded in the recording layer 101 to the reproducing layer 103 depending on the temperature. When reproducing the information recorded in the data part of the track in this manner, the temperature distribution of the laser power at the time of the reproduction is utilized to form a magnetic front mask 105 and a rear mask 106 at parts other than the reproducing position, so that it is possible to reproduce only the necessary information from the magneto-optical disk. In other words, in a case where the information recorded in the data part has a minimum mark length of 0.38 &mgr;m and this information is reproduced using a laser beam having a wavelength of 680 nm, for example, it is possible to reproduce only the necessary information from the magneto-optical disk by forming the masks 105 and 106, even if the spot diameter of the laser beam is approximately 1 &mgr;m and is approximately 3 times the minimum mark length.
However, the ID part of the control track is recorded by forming the concavo-convex parts (embossed pits) on the substrate of the magneto-optical disk. For this reason, even if an attempt is made to record the information in the ID part of the control track with the same density as the data part of the control track, the MSR cannot be used, and there was a problem in that the information recorded in the ID part cannot be reproduced accurately. In other words, in the case where the spot diameter of the laser beam is approximately 1 &mgr;m as described above, for example, approximately 3 pits fall within the beam spot even if an attempt is made to reproduce the pit having the minimum mark length of 0.38 &mgr;m, and it is possible to reproduce the information from only the necessary one of the 3 pits. This is because there is no known means for masking the information from the pits other than the necessary pit from among the 3 pits which fall within the beam spot.
Next, a description will be given of a particular format of the optical disk 72 used in this embodiment. For the sake of comparison, FIGS. 8A and 8B show a track format of a conventional optical disk having a diameter of 90 mm, a memory capacity of 640 MB and in conformance with the ISO/IEC15041, and FIGS. 9A and 9B show a sector format of this conventional optical disk. In the optical disk having the diameter of 90 mm, the memory capacity of 640 MB and in conformance wit the ISO/IEC15041, the minimum mark length of the ID part and the data part is set to 0.64 &mgr;m for both the control track and the data track, and approximately the limit mark length is reached when the wavelength of the laser beam used is 680 nm.
In order to achieve a memory capacity of 1.3 GB which is approximately 2 times the memory capacity of 640 MB using the above described optical disk having the diameter of 90 mm, the memory capacity of 640 MB and in conformance with the ISO/IEC15041, it is necessary to set the minimum mark length to 0.32 &mgr;m. In the data part 206 of the data track 201 on the optical disk 72, it is possible to realize a minimum mark length of 0.32 &mgr;m utilizing the MSR. But in the ID part 205 of the data track 201 and the ID part 205 and the data part 206 of the control track 202, it becomes impossible to reproduce the information if the minimum mark length is set to 0.32 &mgr;m. Hence, the minimum mark length is set to 0.64 &mgr;m as in the conventional case in the ID part 205 of the data track 201 and the ID part 205 and the data part 206 of the control track 202. The ratio with respect to the entire storage capacity of the optical disk 72 occupied by the ID part 205 of the data track 201 and the control track 202 is small, and thus, the storage capacity of the optical disk 72 as a whole will not be greatly reduced by such an arrangement. The track format for this case is shown in FIGS. 10A and 10B, and the sector format for this case is shown in FIGS. 11A, 11B and 11C. In FIGS. 11A through 11C, those parts which are the same as those corresponding parts in FIGS. 9A and 9B are designated by the same reference numerals.
In this case, the recording density in the track longitudinal direction is 0.57 &mgr;m, for example, on the control track 202 and in the ID part 205 of the data track 201. The recording density in the track longitudinal direction is 0.29 &mgr;m, for example, in the data part 206 of the data track 201.
In order to achieve a memory capacity of 1.3 GB which is approximately 2 times the memory capacity of 640 MB using the above described optical disk having the diameter of 90 mm, the memory capacity of 640 MB and in conformance with the ISO/IEC15041, it is necessary to set the minimum mark length to 0.32 &mgr;m. In the data part 206 of the data track 201 on the optical disk 72, it is possible to realize a minimum mark length of 0.32 &mgr;m utilizing the MSR. But in the ID part 205 of the data track 201 and the ID part 205 and the data part 206 of the control track 202, it becomes impossible to reproduce the information if the minimum mark length is set to 0.32 &mgr;m. Hence, the minimum mark length is set to 0.64 &mgr;m as in the conventional case in the ID part 205 of the data track 201 and the ID part 205 and the data part 206 of the control track 202. The ratio with respect to the entire storage capacity of the optical disk 72 occupied by the ID part 205 of the data track 201 and the control track 202 is small, and thus, the storage capacity of the optical disk 72 as a whole will not be greatly reduced by such an arrangement. The track format for this case is shown in FIGS. 12A and 12B, and the sector format for this case is shown in FIGS. 13A, 13B and 13C. In FIGS. 13A through 13C, those parts which are the same as those corresponding parts in FIGS. 9A and 9B are designated by the same reference numerals.
In order to achieve a memory capacity of 2.0 GB which is approximately 3 times the memory capacity of 640 MB using the above described optical disk having the diameter of 90 mm, the memory capacity of 640 MB and in conformance with the ISO/IEC15041, it is necessary to set the minimum mark length to 0.21 &mgr;m. In the data part 206 of the data track 201 on the optical disk 72, it is possible to realize a minimum mark length of 0.21 &mgr;m utilizing the MSR. But in the ID part 205 of the data track 201 and the ID part 205 and the data part 206 of the control track 202, it becomes impossible to reproduce the information if the minimum mark length is set to 0.21 &mgr;m. Hence, the minimum mark length is set to 0.64 &mgr;m as in the conventional case in the ID part 205 of the data track 201 and the ID part 205 and the data part 206 of the control track 202. The ratio with respect to the entire storage capacity of the optical disk 72 occupied by the ID part 205 of the data track 201 and the control track 202 is small, and thus, the storage capacity of the optical disk 72 as a whole will not be greatly reduced by such an arrangement. The track format for this case is shown in FIGS. 14A and 14B, and the sector format for this case is shown in FIGS. 15A, 15B and 15C. In FIGS. 15A through 15C, those parts which are the same as those corresponding parts in FIGS. 9A and 9B are designated by the same reference numerals.
In order to achieve a memory capacity of 2.0 GB which is approximately 3 times the memory capacity of 640 MB using the above described optical disk having the diameter of 90 mm, the memory capacity of 640 MB and in conformance with the ISO/IEC15041, it is necessary to set the minimum mark length to 0.21 &mgr;m. In the data part 206 of the data track 201 on the optical disk 72, it is possible to realize a minimum mark length of 0.21 &mgr;m utilizing the MSR. But in the ID part 205 of the data track 201 and the ID part 205 and the data part 206 of the control track 202, it becomes impossible to reproduce the information if the minimum mark length is set to 0.21 &mgr;m. Hence, the minimum mark length is set to 0.64 &mgr;m as in the conventional case in the ID part 205 of the data track 201 and the ID part 205 and the data part 206 of the control track 202. The ratio with respect to the entire storage capacity of the optical disk 72 occupied by the ID part 205 of the data track 201 and the control track 202 is small, and thus, the storage capacity of the optical disk 72 as a whole will not be greatly reduced by such an arrangement. The track format for this case is shown in FIGS. 16A and 16B, and the sector format for this case is shown in FIGS. 17A, 17B and 17C. In FIGS. 17A through 17C, those parts which are the same as those corresponding parts in FIGS. 9A and 9B are designated by the same reference numerals.
In the Specific Examples 1 through 4 described above, the recording density is improved by setting the mark length to {fraction (1/2, 1/3)}, . . . , based on the optical disk having the diameter of 90 mm, the storage capacity of 640 MB and in conformance with the ISO/IEC15041. However, it is also possible to realize an optical disk having a storage capacity of 1.3 GB by reducing the track pitch from 1.1 &mgr;m to 0.9 &mgr;m and reducing the mark length from 0.64 &mgr;m to 0.38 &mgr;m, for example. In this case, the sector format may be the same as that shown in FIGS. 13A through 13C.
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Patent number: 6449231
Inventor: Takehiko Numata (Kawasaki)
Application Number: 09/232,927
Current U.S. Class: Of Record Carrier (369/53.2); Track Data Format/layout (369/275.3)