Dynamic information storage or retrieval – Dynamic mechanism subsystem – Having power driven transducer assembly
Patent
1998-08-19
2000-02-01
Cao, Allen T.
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Having power driven transducer assembly
G11B 1730
Patent
active
060211075
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an optical pick-up device and a recording and/or reproducing apparatus for optical disc used for carrying out recording and/or reproduction of information signals with respect to two kinds of optical discs different in kind, and more particularly to an optical pick-up device and a recording and/or reproducing apparatus for optical disc, which permit recording and/or reproduction of information signals with respect to two kinds of optical discs different in kind by selectively using first and second object lenses (objectives) attached on a single bobbin.
BACKGROUND ART
Hitherto, as recording media for information signals such as sound signals and/or video signals, and data, etc. processed at information processing equipment such as computer, etc., various kinds of optical discs have been used and have been proposed.
As the optical disc of this kind, there are used optical discs adapted for recording sound signals and/or data, etc. processed at information processing equipment such as computer, etc., and having diameter caused to be 120 mm or 80 mm and thickness caused to be 1.2 mm. Such optical discs are called Compact Disc (CD).
Moreover, there are also used video discs which are optical discs adapted for mainly recording video signals as information signal, and having diameter caused to be 300 mm or 200 mm and thickness caused to be 1.2 mm.
Further, with realization of multi-media of information signals, there has been demand for realization of wide variety and vast (gigantic) quantity of information signals such as picture data or sound data, etc. which are handled at a time. To satisfy such demand, as optical disc in which the medium itself has been miniaturized while realizing high recording density, there have been proposed optical discs in which two optical discs each having diameter caused to be 120 mm and thickness of the disc base (substrate) caused to be 0.6 mm are stuck to each other so that the entire thickness is 1.2 mm, and optical discs in which optical disc having thickness of 0.6 mm and disc reinforced plate having thickness of 0.6 mm are stuck to each other so that the entire thickness is caused to be 1.2 mm. Such optical discs are generally called Digital Video Disc (DVD).
In general, the optical disc constituted as a recording medium for information signals are adapted as shown in FIG. 1 so that non-signal recording areas 202, 203 are respectively provided at the inner circumferential side area of the outer periphery of a center hole 201 formed at the central portion and the outermost circumferential side area, and a signal recording area 204 where information signals are recorded is provided within the area encompassed by the inner circumferential side non-signal recording area 202 and the outer circumferential side non-signal recording area 203. At the inner circumferential side of the signal recording area 204, there is provided a TOC (Table of Contents) area 205 in which addresses of information signals recorded in the signal recording area and management information such as table (of contents) of recording contents, etc. are recorded. Further, in the optical disc, in the state where the innermost circumferential side position of the TOC area is caused to be read starting position of information signals, i.e., lead-in position, read operation of information signals recorded on the optical disc is started from the lead-in position. In addition, in CD 210 having diameter caused to be 120 mm, the lead-in position is set at the position where radius R.sub.1 from the disc center O.sub.1 is 23 mm.
In order to carry out read operation of information signals recorded on this optical disc, the optical pick-up device is caused to be moved toward the innermost circumferential side position of the optical disc. At this time, the object lens (objective) which focuses light beams emitted from the light source of the optical pick-up device to irradiate them onto the optical disc is adapted so that its optical axis is caused to be in correspondence with
Takahashi Katsuya
Tsukahara Nobuhiko
Cao Allen T.
Sony Corporation
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