Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2000-07-11
2002-07-30
Miller, Brian E. (Department: 2652)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S053190
Reexamination Certificate
active
06426925
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a recording and/or reproducing apparatus including an optical pickup in which an objective lens is arranged to converge and irradiate light beams onto a signal recording surface of an optical disk rotated by a rotating drive mechanism, and an optical pickup apparatus for such a recording and/or reproducing apparatus. More particularly, the present invention relates to a recording and/or reproducing apparatus having an adjustment mechanism for adjusting a tilted optical axis of an objective lens against an optical disk, and an optical pickup apparatus therefore.
BACKGROUND ART
In a conventional optical disk intended to be used as a recording medium for information signals, it has been proposed to increase a recording density in the optical disk so as to have a large recording capacity. An optical disk for a high recording density is designed to have a narrow track width and a small pitch between tracks, each of which information signals record.
To accurately read information signals recorded in the high-density optical disk, it is necessary to scan a recording track having a narrow track width and a small track pitch by accurately converging a light beam onto that track. Accurately converging light beams onto such a recording track requires an objective lens with a large numerical aperture (NA).
An objective lens with a large numerical aperture (NA) has a short focal length. Such an objective lens generates a small beam spot to be converged on a recording track of the optical disk. An optical disk is mounted on the disk rotating drive mechanism and is rotated thereby. If the optical disk is bent and is deflected, the disk causes a skew that prevents a light beam from being irradiated perpendicularly onto the optical disk. Such a skew also prevents a light beam from being applied accurately to a specified recording track on the optical disk, thus disabling information signals from being read accurately.
The objective lens converges and irradiates light beams onto the signal recording surface of the optical disk. A light beam irradiated onto the optical disk must be applied accurately and perpendicularly to the optical disk without a skew. For this purpose, there has been proposed an optical pickup apparatus provided with a skew adjustment mechanism for adjusting a tilt of the objective lens in accordance with a tilt of the optical disk rotated by the rotating drive mechanism.
With a recording and/or reproducing apparatus that uses optical disks as recording media, a rotating drive mechanism is unmovably arranged for rotating an optical disk, and an optical pickup apparatus is moved along a diameter of the rotating optical disk across inner and outer peripheries thereon. Thereby, the recording or reproducing of information signals is performed by scanning recording tracks on the optical disk with optical beams. Recording and/or reproducing apparatus of this type is constructed to provide a skew adjustment by tilting the entire optical pickup apparatus including an optical pickup transfer mechanism.
In order to tilt the optical pickup apparatus including the transfer mechanism, a tilt-adjustable support member is provided on a base on which the disk rotating drive mechanism and the like are mounted. This support member supports the optical pickup apparatus in a movable fashion and carries the transfer mechanism. Since the support member is movable on the base, a skew adjustment is made by adjusting a tilt of the optical pickup apparatus.
As mentioned above, the skew adjustment mechanism adjusts a skew by accordingly tilting the support member that supports the optical pickup apparatus in a movable fashion. In the skew adjustment mechanism of this type, the optical pickup apparatus moves on the support member, and thus a supporting point for the tilt varies with the optical pickup apparatus. When the support member is tilted, a displacement amount of the optical pickup apparatus varies with a moved position. Especially when the optical pickup apparatus moves to a position that is far from the supporting point for tilting the support member, just a slight tilt of the support member greatly displaces the optical pickup apparatus. The objective lens irradiating a light beam onto the optical disk moves remarkably, causing a tracking error that disables a light beam from scanning a specified recording track. When a tracking error occurs, the optical pickup apparatus is incapable of accurate tracking and cannot correctly read information signals from the optical disk.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a new recording and/or reproducing apparatus and a new optical pickup apparatus therefore that solve problems found in conventional recording and/or reproducing apparatuses and optical pickup apparatuses.
It is another object of the present invention to provide a recording and/or reproducing apparatus and an optical pickup apparatus therefore that can accurately adjust a skew of light beams irradiated onto an optical disk mounted and rotated on a rotating drive mechanism, and accurately read or write information signals from or to the optical disk.
It is still another object of the present invention to provide a recording and/or reproducing apparatus and an optical pickup apparatus therefore that can accurately read or write information signals to a high-density optical disk.
In order to attain the above-mentioned objects, a recording and/or reproducing apparatus according to the present invention comprises: a rotating drive mechanism provided to mount and rotate a disk with at least one signal recording surface; a transfer mechanism for transferring the rotating drive mechanism along a diameter of the mounted disk; an optical pickup having at least one objective lens to converge a light beam on the recording disk surface; a detection unit provided to irradiate a light beam onto the disk mounted on the rotating drive mechanism and detect a tilt of the disk mounted on said rotating drive mechanism based on the light beam returned from the disk; and an adjustment mechanism for providing a rotative movement based on a detection result from the detection unit around a center-axis line orthogonal to a line formed between an optical axis of the objective lens and the center of the disk mounted on the rotating drive mechanism.
This recording and/or reproducing apparatus performs a skew adjustment by adjusting a tilt of the objective lens against the signal recording surface of the optical disk based on a detection result from the detection unit that detects a return light beam that is irradiated onto the disk and is reflected thereon.
The recording and/or reproducing apparatus according to the present invention is so configured that a distance from the objective lens to a center axis orthogonal to a line formed between an optical axis of the objective lens and the center of the disk mounted on the rotating drive mechanism becomes shorter than a distance from the center axis to a point of action for the optical pickup driven by the adjustment mechanism.
The adjustment mechanism is provided with a cam and a motor. The cam rotates the optical pickup around the center axis orthogonal to a line formed between an optical axis of the objective lens and the center of the disk mounted on the rotating drive mechanism. The motor drives the cam based on a detection result from the detection unit that detects a return light beam that is irradiated onto the disk and is reflected thereon.
Further, the recording and/or reproducing apparatus according to the present invention comprises: a rotating drive mechanism that mounts and rotates a disk with at least one signal recording surface an optical pickup having at least one objective lens to converge a light beam on the recording disk surface; a detection unit provided to irradiate a light beam onto the disk mounted on the rotating drive mechanism and detect a tilt of the disk mounted on the rotating drive mechanism based on the light beam returned from the disk; and an
Miller Brian E.
Sony Corporation
LandOfFree
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