Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Reexamination Certificate
1999-12-21
2001-07-10
Young, W. R. (Department: 2651)
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
C369S044230
Reexamination Certificate
active
06259668
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application No. 96-3603, filed Feb. 14, 1996, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording/reproducing apparatus having an optical pickup device, and more particularly, to a recording/reproducing device having an optical pickup device which enables reading out of information from optical disks having different thicknesses and enables recording information thereon.
In the optical pickup of the recording/reproducing device, an objective lens faces a recording surface of an optical disk for focusing light to record information onto the recording surface of the disk or receiving light reflected from the surface of the disk to read information.
2. Description of the Related Art
Recently, research on an optical drive has been conducted in which the drive can seat disks having different thicknesses by adopting a lens device including both a hologram lens and a refractive lens.
FIGS. 1 and 2
show focusing states of a conventional optical pickup device of light incident by zero order diffracted light and 1st order diffracted light on a thin disk and a thick disk, respectively. A refractive lens
2
and a hologram lens
1
are disposed in sequence along an optical path from each of disks
3
a
and
3
b
. The hologram lens
1
has a lattice pattern
11
for diffracting light that passes through the hologram lens
1
. Thus, while light
4
emitted from a light source (not shown) passes through the hologram lens
1
, light is divided into a diffracted 1st order light
41
and a non-diffracted zero order light
40
, respectively. While the diffracted 1st order light
41
and the non diffracted zero order light
40
pass through each of the objective lenses
2
, the light
41
and
40
are focused with different intensities, thereby forming a focus on the thin disk
3
a
and on the thick disk
3
b.
The lens device described above can record information on disks having different thicknesses and read out information therefrom using zero order light and 1st order light. However, as the incident light is divided into zero order light and 1st order light, the efficiency of light use is lowered. That is, since the incident light is divided into zero order light and 1st order light by the hologram lens
1
, the actual amount of light used for recording information is only 15%. Also, when information is reproduced, information is included in only one of zero order light and 1st order light. Thus, 1st order light or zero order light without information is detected by a photo detector and the detected light may produce noise. The above problem can be overcome by processing the hologram lens of the lens device. However, this requires a high precision process of etching a fine pattern on the hologram, thereby increasing the manufacturing cost.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an optical pickup device wherein parts thereof can be manufactured and assembled easily at low cost.
It is another object of the present invention to provide a recording and/or reproducing apparatus which has high efficiency of light use and low spherical aberration.
To achieve the above and other objects, there is provided a recording and/or reproducing apparatus comprising an optical pickup device and a processing unit, wherein the optical pickup device comprises a light source; an objective lens facing a disk having a light passing region divided into central, intermediate and periphery regions respectively corresponding to a near axis area, an intermediate axis area and a far axis area of incident light, wherein the curvature of the central and peripheral regions are optimized for a thin disk and that of the intermediate region is optimized for a thick disk; a photo detector for detecting light reflected from the disk; a beam splitter, disposed between the objective lens and the light source, for transmitting/reflecting light from the light source toward the objective lens and for reflecting/transmitting light reflected from the disks toward the photo detector; and the processing unit processes an information signal to control the incident light generated by the light source, and processes the detected light from the photodetector.
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Lee Chul-woo
Yoo Jang-hoon
Chu Kim-Kwok
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
Young W. R.
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