Optical disc having a substrate with micro-embossments for tracking guides
An optical disc includes a substrate having micro-embossments, in which flat portions referred to as lands, and track guides, referred to as hills, and which protrude from the surfaces of the flat portions are formed. A reflective layer is formed on the substrate, a dielectric layer is formed on the reflective layer, a recording layer is formed on the dielectric layer, and a protective layer is formed on the recording layer. Thus, the lands and hills on the substrate of the optical disc enable disc fabrication to more easily facilitate manufacturing of the optical disc. Accordingly, tracks of the disc can be narrowed, to thereby enhance a recording density of the optical disc.
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This application is a divisional of U.S. application Ser. No. 09/513,687, now pending, which claims the benefit of Korean Application No. 99-13453, filed Apr. 16, 1999, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to an optical disc, and more particularly, to an optical disc having an enhanced recording density, and fabrication of the optical disc is facilitated and tracks are narrowed.
2. Description of the Related Art
In general, a near field recording drive is used for recording data on a disc or reproducing data from the disc in which an optical spot focused on the disc forms a near field. In the near field recording drive, a light flying head and a disc are spaced from each other by a predetermined interval, in order to record, reproduce and erase the data with respect to the disc to which a near field is formed. This technology is disclosed in detail in U.S. Pat. No. 5,470,627, which will be briefly described below with reference to
A recording/reproducing operation of the
A near field is formed between the surface of the objective lens 30 on which the laser light 11 is focused and the optical disc 40. As a result, information is recorded on the optical disc 40 and read out from the optical disc 40 via the near field. That is, the light focused on the surface of the optical disc 40 becomes a heat source, to heat a recording layer of the optical disc 40 higher than a predetermined temperature. If a current flows through a magnetic coil during heating to thereby generate a constant magnetic field, the vertical component of the magnetic field forms a vertical magnetic sphere on a recording layer of the disc, to thereby perform a data recording. When the recorded data is reproduced, the light flying head irradiates laser light toward the surface of the optical disc 40 on the vertical magnetic sphere and reads data according to a deflection direction of the laser light reflected from the surface of the optical disc 40. That is, the reflective light reflected from the reflective layer coated on the surface of the optical disc 40 is incident to the objective lens 30. The tracking during recording and reproducing is possible as the patterns of the lands 50 and the grooves 60 formed on the substrate 45 are distinguished by the reflective layers.
A more detailed structure of the optical disc 40 used in the
As described above, since four or more layers are deposited on the substrate on which the grooves are formed in the optical disc, the grooves are backfilled with sputtering particles. As a result, a signal detected by a light flying head is feeble. Meanwhile, there is a method for equaling the groove width and deepening and narrowing the groove depth so that the signal detected by the light flying head becomes greater. However, this method makes disc fabrication difficult since a stamper for fabricating a basic form of a substrate should be fabricated in the form of an inverse V-shape.
SUMMARY OF THE INVENTIONTo solve the above and other problems, it is an object of the present invention to provide an optical disc for use in a narrow track pitch in which a groove deformation is prevented at the time of a multilayer formation and fabrication of a high density disc is facilitated.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To accomplish the above and other objects of the present invention, there is provided an optical disc comprising: a substrate having that portions and micro-embossments, which are track guides, protruding from surfaces of the flat portions; a reflective layer formed on the surfaces of the flat portions and the micro-embossments of the substrate; a dielectric layer formed on the reflective layer; a recording layer formed on the dielectric layer; and a protective layer formed on the recording layer.
BRIEF DESCRIPTION OF THE DRAWINGSThe above object and other advantages of the present invention will become more apparent by describing the preferred embodiment thereof in more detail with reference to the accompanying drawings in which:
A preferred embodiment of the present invention will be described with reference to the accompanying drawings, wherein like reference numerals refer to like elements throughout.
The following description relates to each surface of the substrate 405 as there are two surfaces of the substrate 405, each having the lands 600 and the hills 500. The thin-film reflective layer 401 is formed on the surface of the substrate 405, which includes the surfaces of the lands 600 and the hills 500. On the outer surface of the reflective layer 401 are formed a dielectric layer 402 for boundary of a recording layer 403 and the recording layer 403 for recording data. Finally, a transparent protective layer 404 for protecting the recording layer 403 is formed on the recording layer 403. The thickness of the protective layer 404 is to avoid an occurrence of an unstable float of the light flying head or a stiction phenomenon, due to unevenness of the disc surface. For this purpose, the protective layer 404 is formed higher than the hills 500 embossed on the substrate 405 or a pit plane (not shown) for storing information thereon. The surface of the protective layer 404 having the above thickness maintains flatness. As described above, in the case that the hills 500 are provided as a basic pattern of the substrate 405 of the optical disc 400 shown in
A process for recording and reproducing data on and from the optical disc 400 shown in
During recording, laser light 11 is incident to the objective lens 30 to thereby form an optical spot on the bottom of the objective lens 30. The formed optical spot becomes a small spot which is inversely proportional with a refractive index of the material of the objective lens 30. The optical spot becomes abruptly large after it comes out in the air. However, since the optical disc 400 is close to the objective lens 30, at a distance of λ/10 to λ/5, a near field is generated. Thus, the optical spot is transferred to the optical disc 400 with the size of the optical spot maintained. During reproduction, the optical spot is reflected from the reflective layer 401 coated on the outer side of the substrate 405 of the optical disc 400 shown in
In the above embodiment, the optical disc has been described with respect to a double-sided disc. However, the present invention can be applied to a single-sided disc.
As described above, the present invention includes the lands and hills on the substrate of the optical disc, to thereby facilitating disc fabrication. Accordingly, tracks of the disc can be narrowed, to thereby enhance a recording density.
Although a few preferred embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
Claims
1. A method of forming an optical disc which stores data, comprising:
- stamping a substrate to have first protrusions extending from a first surface of the substrate, wherein the first protrusions are track guides for the data.
2. The method of claim 1, further comprising:
- forming a first reflective layer on the first surface and the first protrusions;
- forming a first dielectric layer on the first reflective layer;
- forming a first recording layer on the first dielectric layer; and
- forming a first protective layer on the first recording layer.
3. The method of claim 2, wherein the first protective layer is further from the first surface than peaks of the first protrusions.
4. The method of claim 1, further comprising:
- stamping the substrate to have second protrusions extending from a second surface of the substrate, wherein the second protrusions are track guides for the data.
5. The method of claim 2, further comprising:
- stamping the substrate to have second protrusions extending from a second surface of the substrate, wherein the second protrusions are track guides for the data;
- forming a second reflective layer on the second surface and the second protrusions;
- forming a second dielectric layer on the second reflective layer;
- forming a second recording layer on the second dielectric layer; and
- forming a second protective layer on the second recording layer.
6. The method of claim 5, wherein the second protective layer is further from the second surface than peaks of the second protrusions.
7. A method of recording data on an optical disc including a substrate having a surface with protrusions extending from the surface, wherein the protrusions are track guides for the data, a reflective layer formed on the surface and the protrusions, a dielectric layer formed on the reflective layer, a recording layer formed on the dielectric layer, and a protective layer formed on the recording layer, the method comprising:
- moving an objective lens of a flying head to a distance of λ/10 to λ/5 from the protective layer; and
- forming an optical spot at a bottom of the objective lens to generate a near field, thereby recording the data on the recording layer based upon the protrusions.
8. A method of reproducing data from an optical disc including a substrate having a surface with protrusions extending from the surface, wherein the protrusions are track guides for the data, a reflective layer formed on the surface and the protrusions, a dielectric layer formed on the reflective layer, a recording layer formed on the dielectric layer and storing the data, and a protective layer formed on the recording layer, the method comprising:
- moving an objective lens of a flying head to a distance of λ/10 to λ/5 from the protective layer; and
- forming an optical spot at a bottom of the objective lens to generate a near field; and
- reflecting the optical spot from the reflective layer after passing through the cording layer, using the protrusions, to reproduce the data.
Type: Application
Filed: Mar 30, 2005
Publication Date: Aug 4, 2005
Applicant: Samsung Electronics Co., Ltd. (Suwon-si)
Inventors: Yong-Hoon Lee (Suwon-city), Chul-Woo Lee (Sungnam-city), Chong-Sam Chung (Sungnam-city), Kun-Ho Cho (Suwon-city)
Application Number: 11/092,761