This application claims the priority benefit of Taiwan application serial no. 96130326, filed Aug. 16, 2007. All disclosure of the Taiwan application is incorporated herein by reference.
1. Field of the Invention
The present invention generally relates to an optical recording medium, in particular, to a three-level recording phase-change optical disc.
2. Description of Related Art
Compared with conventional magnetic recording medium, optical recording medium has become one of the most indispensable recording medium due to its advantages of large recording capacity, easy-to-storage property, long storage period, low manufacturing cost, and high data protection etc. With the advanced high techniques of laser photoelectric products and multimedia video/audio compression, the development of optical recording medium is going toward a bigger capacity, a higher recording density, and a smaller size.
Generally speaking, optical recording media can be categorized into compact disc (CD) and digital versatile disc (DVD), wherein DVD is currently the mainstream of optical recording media. However, with the widespread of multimedia application information, the capacity of DVD optical disc has become insufficient because most media data contain text, audio, and video data of large quantity. Accordingly, a high-density blu-ray disc (BD) which can store about 25 GB per layer by using blu-ray to write and record has been developed in order to increase the capacity of a recording medium effectively.
Among various optical recording media, the most popular one is write once recording medium (WORM), such as write once compact disc-recordable (CD-R), write once digital versatile disc-recordable (DVD-R), and write once blu-ray disc-recordable (BD-R) etc. The recording layer in such a write once optical recording medium is made of an organic dye or an inorganic material. Compared to the write once optical recording medium having its recording layer made of organic dye, the write once optical recording medium having its recording layer made of inorganic material has such advantages as simple fabrication process, low contamination, high tolerances in light and weather, etc., therefore it is one of the most potential products in optical recording medium.
Generally speaking, with different write mechanisms, recording layers made of inorganic materials of a write once optical recording medium have different material systems. For example, for a write once optical recording medium, recording points of the recording layer made of inorganic material can be formed by an alloy structure change with interface reaction of material layers or phase changes. An inorganic phase-change optical disc usually has two recording layers. While heated by a laser, the two recording layers produce phase changes so as to form a recording region, wherein the recording region can changes the reflective index of the optical disc as recording points for signal recording identification. However, only two-level reading can be achieved, therefore the recording density of the optical disc cannot be improved in foregoing inorganic phase-change optical disc.
Therefore, the present invention provide a method of recording and reproducing information of a three-level recording phase-change optical disc, wherein three recording regions can be formed through phase changes of three different reflective indexes in recording, so that three-level reading can be achieved and accordingly the recording density of the optical disc can be improved.
The present invention provides a three-level recording phase-change optical disc including a first recording layer, a second recording layer, a third recording layer, a reflective layer, and a first dielectric layer. The second recording layer and the third recording layer are sequentially disposed on the first recording layer. The reflective layer is disposed on the third recording layer. The first dielectric layer is disposed between the reflective layer and the third recording layer. The first recording layer, the second recording layer, and the third recording layer form three recording regions.
According to embodiments of the present invention, a first recording region is formed by the first recording layer, the second recording layer, and the third recording layer; wherein the first recording region shows a first reflective index; a phase change caused by the first recording layer and the second recording layer under a first power so as to form a second recording region, and the second recording region shows a second reflective index; a phase change happened at the first recording layer, the second recording layer and the third recording layer under a second power so as to form a third recording region, and the third recording region shows a third reflective index.
According to the embodiments of the present invention, the first power is smaller than the second power.
According to the embodiments of the present invention, the first power and the second power are both between 5 mW and 30 mW.
According to the embodiments of the present invention, the differences between the first reflective index, the second reflective index, and the third reflective index have to be greater than 5%, so that a reading apparatus can distinguish these different reflective indexes.
According to the embodiments of the present invention, the material of the first recording layer may be copper (Cu) alloy.
According to the embodiments of the present invention, the material of the first recording layer may be copper (Cu)/magnesium (Mg) alloy or copper (Cu)/zinc(Zn) alloy.
According to the embodiments of the present invention, the material of the first recording layer may be copper (Cu)/silicon (Si) composition.
According to the embodiments of the present invention, the thickness of the first recording layer is between 3 nm and 10 nm.
According to the embodiments of the present invention, the material of the second recording layer may be silicon.
According to the embodiments of the present invention, the thickness of the second recording layer is between 3 nm and 10 nm.
According to the embodiments of the present invention, the material of the third recording layer may be aluminium (Al) alloy.
According to the embodiments of the present invention, the material of the third recording layer may be aluminium (Al)/zinc (Zn) alloy, aluminum(Al)/copper alloy, aluminum-titanium (Ti) alloy, or aluminum (Al)/magnesium (Mg) alloy.
According to the embodiments of the present invention, the thickness of the third recording layer is between 3 μm and 10 μm.
According to the embodiments of the present invention, the material of the first dielectric layer may be SiNx, ZnS—SiO2, AlNx, SiC, GeNx, TiNx, TaOx, or YOx, or any compound made by more than one of SiNx, ZnS—SiO2, AlN, SiC, GeNx, TiNx, TaOx, or YOx.
According to the embodiments of the present invention, the material of the reflective layer may be Ag, Au, Al, Ti, Pd, Cr, Mo, W, Ta, or an alloy containing at least one of Ag, Au, Al, Ti, Pd, Cr, Mo, W, and Ta.
According to one of the embodiments of the present invention, the three-level recording phase-change optical disc may be a digital versatile disc (DVD).
According to one of the embodiments of the present invention, the three-level recording phase-change optical disc may further include a first substrate, wherein the first recording layer is disposed on the first substrate.
According to one of the embodiments of the present invention, a second dielectric layer may be further disposed between the first substrate and the first recording layer.
According to one of the embodiments of the present invention, the material of the first substrate may be glass (SiOx), polycarbonate (PC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), or polyethylene (PE).
According to one of the embodiments of the present invention, a second substrate may be further disposed on the reflective layer.
According to one of the embodiments of the present invention, the material of the second substrate may be SiOx, PC, PMMA, PET or PE.
According to one of the embodiments of the present invention, the three-level recording phase-change optical disc may be a blu-ray disc (BD).
According to one of the embodiments of the present invention, a substrate may be further disposed on the reflective layer.
According to one of the embodiments of the present invention, the material of the substrate may be SiOx, PC, PMMA, PET or PE.
According to one of the embodiments of the present invention, the three-level recording phase-change optical disc may further include a cap layer, wherein the cap layer is disposed on the first recording layer.
According to an embodiment of the present invention, a second dielectric layer may be further disposed between the cap layer and the first recording layer.
According to one of the embodiments of the present invention, the material of the cap layer may be PC.
In the present invention, three recording layers are disposed in an optical disc for recording data. While writing data into the optical disc, three recording regions having three different reflective indexes are formed in the optical disc through phase changes of the three recording layers. Accordingly, three-level reading to the optical disc can be achieved.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
Referring to
To be specific, the material of the first recording layer 104 may be a copper/silicon composition composed of copper and 10%˜35% of silicon, a copper/magnesium alloy composed of copper and 15%˜50% of magnesium, or a copper/zinc alloy composed of copper and 30%˜50% of zinc. The material of the third recording layer 108 may be an aluminum/copper alloy composed of aluminum and 10%˜50% of copper, an aluminum/titanium alloy composed of aluminum and 0.9%˜50% titanium, or an aluminum/magnesium alloy composed of aluminium and 30%˜50% magnesium.
The first recording layer 104, the second recording layer 106, and the third recording layer 108 can form three recording regions. When there is no phase change at the first recording layer 104, the second recording layer 106, and the third recording layer 108, a first recording region is formed and the first recording region sends back a first reflective index when the optical disc is read. When a phase change occurred at the first recording layer and the second recording layer under a first power, a second recording region is formed and the second recording region shows a second reflective index when the optical disc is read. When a phase change is occurred at the first recording layer, the second recording layer, and the third recording layer under a second power, a third recording region is formed and the third recording region shows a third reflective index when the optical disc is read. The first power and the second power are both between 5 mW and 30 mW, and the first power is smaller than the second power.
With the three different reflective indexes, three-level reading can be performed on the optical disc provided by the present invention. In addition, the three-level recording optical disc can be fabricated simply by forming the three recording layers on a substrate in sequence, namely, the optical disc can be fabricated through a well-known single-layer optical disc fabrication process therefore complex fabrication process can be avoided.
Below, a digital versatile disc (DVD) will be described as an example of the three-level recording phase-change optical disc provided by the present invention.
Referring to
The substrate 114 is disposed on the substrate 100. The substrate 100 includes a transparent substrate having a signal surface (with a track pitch of about 0.74 μm). The material of the substrates 100 and 114 may be glass (SiOx), polycarbonate (PC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), polyethylene (PE) or other transparent materials. The thickness of the substrates 100 and 114 is about 0.6 mm.
The first recording layer 104, the second recording layer 106, and the third recording layer 108 are disposed between the substrates 100 and 114 and are sequentially disposed on the substrate 100. The material and thickness of the first recording layer 104, the second recording layer 106, and the third recording layer 108 have been described in the embodiment illustrated in
Referring to
As shown in
Below, a blu-ray disc (BD) will be described as an example of the three-level recording phase-change optical disc provided by the present invention. In the present embodiment, the materials of various layers are the same as those in the embodiment described above and are well-known to those having ordinary knowledge in the art, therefore will not be described herein.
Referring to
The substrate 114′ is disposed on the cap layer 100′. The substrate 114′ includes a transparent substrate having a signal surface (with a track pitch of about 0.32 μm). The thickness of the substrate 114′ is 1.1 mm, and the thickness of the cap layer 100′ is 0.1 mm. The material of the cap layer 100′ may be PC. The third recording layer 108′, the second recording layer 106′, and the first recording layer 104′ are disposed between the substrate 114′ and the cap layer 100′ and are sequentially disposed on the substrate 114′. The reflective layer 112′ is disposed between the third recording layer 108′ and the substrate 114′. The dielectric layer 102′ is disposed between the cap layer 100′ and the first recording layer 104′. The dielectric layer 110′ is disposed between the reflective layer 112′ and the third recording layer 108′.
Similar to the optical disc 10, when data are recorded by lasers of different powers radiated onto the optical disc 10′ through the cap layer 100′, the first recording layer 104′, the second recording layer 106′, and the third recording layer 108′ can form three recording regions which show three different reflective indexes r1′, r2′, and r3′ by the optical disc so that three-level reading can be achieved on the optical disc.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
Number | Date | Country | Kind |
---|---|---|---|
96130326 | Aug 2007 | TW | national |