Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Reexamination Certificate
2001-07-06
2004-12-28
Huber, Paul W. (Department: 2653)
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
Reexamination Certificate
active
06836459
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an optical pickup device for recording or reproducing data on/from optical disks.
BACKGROUND OF THE INVENTION
In recent years, optical disks capable of storing enormous amounts of data at high density have been used in various fields. Optical disks are optical data storage mediums characterized by the capabilities of non-contact data recording or reproduction, and medium interchange. Especially, optimal disks have received attention as external storage mediums for optical disk files or computers.
On optical disks, data are recorded or reproduced by an optical pickup using a semiconductor laser or the like, and the recorded data can be erased and rewritten on some optical disks.
FIG. 21
is a schematic diagram illustrating the structure of a conventional optical pickup device
500
. The optical pickup device
500
is provided with a data recording/reproduction means
502
, and a driving means
512
for driving the data recording/reproduction means
502
. The data recording/reproduction means
502
is provided with a light source holder for recording or reproducing data on/from a disk type recording medium
511
that rotates about an axis
510
, and a fine-adjustment means
504
for finely adjusting the position of the light source holder
503
. The light source holder
503
is provided with a laser beam emission/reception means
515
, a reflection mirror
505
, an object lens
506
, an object lens holder
507
, and an object lens position adjustment means
508
.
The data recording/reproduction means
502
is driven, by the driving means
512
, in the direction of the radius of the recording medium
511
, and records or reproduces data on/from an arbitrary area of the recording medium
511
. The laser beam emission/reception means
515
emits a laser beam
519
, and receives the laser beam
519
reflected at the recording medium
511
. The reflection mirror
505
is a plane mirror that reflects the laser beam
519
. The object lens
506
converges the laser beam
519
reflected by the reflection mirror
505
, onto the signal recording surface of the recording medium
511
. The object lens holder
507
holds the object lens
506
. The object lens position adjustment means
509
drives the object lens holder
507
in the direction perpendicular to the data recording surface of the recording medium
511
so as to bring the laser beam
519
into a focus on the signal recording layer of the recording medium
511
.
In the optical pickup device
500
so constructed, except for an auxiliary laser beam for track servo, a single laser beam
519
is focused on a single recording track on the recording medium
511
, and reading/writing of data from/into the signal recording track is carried out at one time. In this case, since the recording rate or reproduction rate of the optical pickup device
500
to the recording medium
511
depends on the rotation speed of the optical disk, the recording medium
511
must be rotated at a high speed to increase the recording rate or reproduction rate. Therefore, prevention of vibrations caused by that the recording medium
511
is out of balance, and speedup in signal processing are desired.
FIG. 22
is a schematic diagram illustrating a conventional optical pickup device
501
that can perform reading or writing of data from/into plural recording tracks at the same time. In
FIG. 22
, the same reference numerals as those shown in
FIG. 21
denote the same or corresponding parts. The light source holder
503
further includes a diffraction grating
509
and a diffraction grating adjustment means
515
. The diffraction grating
509
splits the laser beam
519
into plural laser beams
514
that are nearly parallel to each other. The diffraction grating adjustment means
515
finely adjusts the diffraction grating
509
so that splitting of the laser beam
519
is appropriately carried out.
As described above, in the optical pickup device
501
shown in
FIG. 22
, the diffraction grating
509
splits the laser beam
519
into the nearly-parallel laser beams
514
, and data are read or written from/into plural recording tracks at the same time using the laser beams
514
, whereby high-speed reading/writing is achieved without increasing the rotation speed of the recording medium
511
. A birefringence material may be used instead of the diffraction grating
509
.
In the conventional optical pickup device
500
or
501
, the focal length in the focusing direction and the focal direction in the tracking direction must be controlled by the object lens adjustment means
508
and the fine-adjustment means
504
, respectively, to bring the laser beam
519
into a focus on the data recording layer of the optical disk
511
. Especially in an optical disk recording apparatus or an optical disk reproduction apparatus that is applicable to both a DVD (Digital Versatile Disk) and a CD (Compact Disk), since the position of a data a recording layer in a recording medium in the vertical direction of the medium (hereinafter referred to as “depth position”) differs between the DVD and the CD due to the difference in their standards, the object lens adjustment means
508
is necessary to bring a laser beam into focuses on the respective data recording layers of the DVD and the CD. Therefore, mechanical driving by the object lens adjustment means
508
and the fine-adjustment means
504
is necessary to control the position of the focus of the laser beam, and excess time and energy for the mechanical driving are required.
Further, in order to bring a laser beam into focuses on the data recording layers of the DVD and the CD, a double-focus lens that can bring a laser beam into the respective focuses may be employed as an object lens, instead of the object lens adjustment means
508
. In this case, however, a signal from one focus is inputted as noise to a signal from the other focus, resulting in degraded signal quality.
Further, in order to record or reproduce data on/from an arbitrary area of the data recording medium
511
, the data recording/reproduction means having a weight including the weights of the object lens adjustment means
508
and the fine-adjustment means
504
must be driven by the driving means
512
. Therefore, excess time and energy are required for driving the data recording/reproduction means
502
.
Furthermore, in the conventional optical pickup device
501
, when plural laser beams are emitted, the intervals of focuses of the respective laser beams are fixed by the physical arrangement of the respective constituents, or it is only possible to change the intervals of focuses of all laser beams
514
at the same time by the diffraction grating
509
. Accordingly, for example, in a three-beam system optical pickup device, although two beams can be brought into focuses on recording tracks, the focus position of the third beam alone cannot be controlled independently. In some cases, reading of data by the third beam cannot be carried out unless using a technique that can read data even when the focus of the beam is not positioned on the recording track, such as an image sensor or the like.
SUMMARY OF THE INVENTION
The present invention is made to solve the above-mentioned problems and has for its object to provide an optical pickup device that realizes speedup and energy saving in driving the data recording/reproduction means with the driving means by reducing the weight of the data recording/reproduction means, that realizes speedup and energy saving in controlling the position of focus of a laser beam by performing the control without using mechanical driver, and that is able to adjust the positions of focuses of plural laser beams independently.
Other objects and advantages of the invention will become apparent from the detailed description that follows. The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the scope of the invention will be apparent to those of skill in the art from the detailed descriptio
Huber Paul W.
Wenderoth , Lind & Ponack, L.L.P.
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