Information reproducing method information reproducing apparatus of multilayer optical disk
A reproducing device and reproducing technology, which are applied in the directions of recording/reproducing by optical methods, beam guiding devices, recording of information on magnetic disks, etc., can solve the problem of taking a lot of time, increasing aberrations of optical systems, and increasing manufacturing costs. Large and other problems to achieve the effect of enhancing convenience
Inactive Publication Date: 2004-06-09
HITACHI CONSUMER ELECTRONICS CORP
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Problems solved by technology
At this time, when the NA is increased, there is a problem that the aberrations caused by the deviation of the optical system, the thickness of the disc substrate, and the tilt error increase.
If it is 2 layers, it must be repeated 2 times; if it is 4 layers, it must be repeated 4 times, and it takes a lot of time from loading to replaying
Moreover, since it is necessary to use a disk in which layer information is recorded on each layer of the recording layer of a multilayer disk, it is necessary to prepare a different stamper for each layer, and the manufacturing cost of the disk will increase.
Method used
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[0032]Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an information reproducing apparatus for realizing the information reproducing method of the multi-layer disc of the present invention. The information playback device of the present invention is broadly classified into an optical sensor and a signal processing control unit. The optical sensor consists of a blue semiconductor laser 101 with a wavelength of 405nm, a collimator lens 102 with a focal length of 13mm for converting laser light into parallel light, a diffraction grating 103, a polarizing beam splitter 104, a straight mirror 105, a spherical aberration correction device 106, 1 / 4 A wavelength plate 107, an objective lens 108, an objective lens actuator 109, a condenser lens 110 with a focal length of 13 mm, a cylindrical lens 111 with a focal length of 200 mm, and a detector 112. For a polycarbonate substrate with a substrate thickness of 0.1mm, the...
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Abstract
When reproducing a multilayer optical disk using a high-numerical-aperture objective, the period of time required before the disk is reproduced is reduced by discriminating recording layers. A spherical aberration signal is detected as a differential signal between focus position fluctuation signals respectively in a central section and in a peripheral section of a reproduced flux of light. A recording layer is discriminated using a quantity of correction of spherical aberration at a zero-crossing point of a level or a spherical aberration signal associated with the differential signal. After adding the spherical aberration for the correction of the discriminated layer, residual spherical aberration is corrected by feedback control using a residual spherical aberration signal.
Description
technical field [0001] The present invention relates to the information reproducing method of information reproducing by laser, especially the necessary layer discrimination method and the detection and correction method of spherical aberration when using blue-violet semiconductor laser and high NA objective lens to reproduce multi-layer disc. Background technique [0002] VCRs that are spreading today generally use video tapes, but recently VCRs that use optical discs are also on the market. [0003] Optical discs are superior to video tapes in terms of random access; in terms of ease of use or almost no image degradation due to repeated playback, time changes, and high density of capacity, VCRs using optical discs will generally be considered more and more in the future . Moreover, the optical disc device is used in various applications such as an external recording device for a computer or a music recording and reproducing device in addition to video recording, and its i...
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IPC IPC(8): G11B7/24G11B7/00G11B7/005G11B7/085G11B7/09G11B7/095G11B7/125G11B7/13G11B7/131G11B7/135G11B7/1353G11B7/1365
CPCG11B7/0908G11B7/1353G11B7/1365G11B7/0901G11B2007/0013G11B7/131G11B7/095G11B7/08505
Inventor 有吉哲夫岛野健宫本治一
Owner HITACHI CONSUMER ELECTRONICS CORP