• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:

    公开号:NL1009126A1
    申请号:NL1009126
    申请日:1998-05-11
    公开日:1999-01-25
    发明作者:Myoung-June Kim；Seong-Seu Kim；Young-Man Ahn；Myong-Do Ro；Du-Seop Yoon；Seung-Tae Jung；Jang-Hoon Yoo；Chul-Woo Lee；Hea-Jung Suh
    申请人:Samsung Electronics Co Ltd；
    IPC主号:
    专利说明:

    Background of the Invention Field of the Invention
    The present invention relates to an optical disc with two or more information recording layers, and more particularly to an optical disc that can be played back compatible by optical disc players of different format standards.
    Generally, multilayer optical disks are manufactured which contain two or more recording layers as a method of increasing the information recording capacity of one optical disk.
    Description of the prior art
    An example of a conventional dual layer optical disk is explained with reference to Fig. 1. As shown in Fig. 1, the optical disk successively comprises from the side illuminated by light a first transparent substrate 11, a first recording layer 13 with an information recording surface, a first adhesive layer 15, an intermediate layer 17, a second adhesive layer 19, a second recording layer 21, and a second transparent substrate 23.
    The first substrate 11 is made of transparent PVC with a thickness of 1 mm, and transmits an incidental lie. The first recording layer 13 is made of an ultraviolet curable resin and is formed on one surface of the first substrate 11. Areas 13a and grooves 13b forming a spiral track are applied to the first recording layer 13. A partially translucent film is formed on the surface 14 of the first recording layer 13 adjacent to the first adhesive layer 15 to transmit part of the incident light. The preferred material of the partially translucent film is material such as zinc selenide (ZnSe), bismuth oxide (BiO), cadmium sulfide (CdS), cadmium telluride (CdTe) or silicon carbide (SiC).
    Furthermore, the second recording layer 21 has a configuration similar to that of the first recording layer 13, and the surface 20 next to the second adhesive layer 19 is provided with a reflective layer having a reflectivity of about 90%. The first and second adhesive layers 15 and 19 and the intermediate layer 17 are layers for joining and spacing between the first recording layer 13 and the second recording layer 21 and for transmitting the incident light. The second substrate 23 made of transparent PVC protects the second recording layer 21.
    In the optical disc manufactured as described above, the reproduction of the recorded information is performed using the incident beam entering from the first substrate 11 and focused by an objective lens 3. The information recorded on the first recording layer 13 can be displayed by adjusting the objective lens 3 to focus a beam 1 on the first recording layer 13, and the information registered on the second recording layer 21 can be displayed by adjusting the objective lens 3 to focus a beam 1 ' on the second recording layer 21.
    Although the optical disc manufactured as described above has the advantage of increasing the recording capacity by dual layers of first and second recording layers 13 and 21, it can only be used by an optical disc player using 650 nm wavelength light for example, a digital versatile disc player with a "read only memory" (DVD-ROM).
    On the other hand, recently in the optical disc player art, the digital versatile disc player is commercially available according to a new standard, capable of realizing high quality sound and images with increased recording capacity. The digital versatile disc player uses a laser that emits light with a wavelength of 650 nm as the light source, while in the compact disc player the wavelength of the laser light is 780 nm and the standard numerical aperture of the objective lens is 0.6. In addition, in the specification of the digital versatile disc for the digital versatile disc player, a thickness of 0.6 mm between the incident surface and the recording surface and a track pitch of 0.74 μτη are the norm, while in the compact disc the thickness is 1.2 mm and the rail pitch is 1.6 μπι.
    Since the above-mentioned digital versatile disc player has been developed in various configurations to display a disc of the compact disc standard, the information recorded on a compact disc can also be displayed by the digital versatile disc player.
    However, information recorded on a digital versatile disc cannot be displayed by a compact disc player due to the difference in specifications.
    Summary of the invention
    To solve this problem, it is an object of the present invention to provide an optical disc with two or more information recording layers capable of compatible playback by optical disc players of different format standards.
    Therefore, to achieve this object, an optical disc capable of being reproduced by different format standard optical disc players and comprising a transparent substrate transmitting incident light is provided, a first recording layer having an information recording surface on which an information signal is recorded. Its recorded information is represented by first wavelength light. Also, the optical disc includes a partially transmissive film formed on one surface of the first recording layer, which exhibits different transmissivity depending on the wavelength of the incident light. Most light of the first wavelength is reflected by the partially translucent film and most light of the second wavelength is transmitted. There is also an intermediate layer that transmits the light transmitted by the partially translucent film, a second recording layer having an information recording surface on which an information signal is recorded. The recorded information is represented by the second wavelength light transmitted by the partially translucent film. Also, a reflective film is formed on the information recording surface of the second recording layer that reflects light focused on the second recording layer.
    Brief description of the drawings
    The foregoing objects and advantages of the invention will become apparent with reference in detail to a preferred embodiment thereof with reference to the attached drawings, in which: Fig. 1 is a sectional view showing an example of a conventional dual layer optical disc; FIG. 2 is a section showing an embodiment of an optical disk according to the invention; FIG. 3 is a graph showing the relationship between the reflectivity and the wavelength of the> partially translucent film of an optical disc according to the present invention; Fig. 4 is a sectional view showing an example of the partially translucent film of an optical disc according to the invention; FIG. 5 is a section showing another example of the partially translucent film of an optical disc according to the invention; FIG. 6 is a graph showing the reflectivity of light beams of first and second wavelengths according to thickness variations of the first dielectric layer of FIG. 5; Fig. 7 is a sectional view of an optical disk according to the present invention and schematically illustrates a mode for using a first recording layer of the optical disk; and FIG. 8 is a view of an optical disk according to the present invention schematically showing a mode for using a first recording layer of the optical disk.
    Detailed description of the invention
    Referring to Fig. 2, an embodiment of an optical disk according to the present invention sequentially from the side illuminated by the light (L) comprises a transparent substrate 31, a first recording layer 33, a partially translucent film 35, an intermediate layer 39, a reflective film 43, a second recording layer 45 and a protective layer 47.
    The transparent substrate 31 transmits incident light (L) and protects the first recording layer 33. The transparent substrate 31 is made of a polymeric material such as transparent PVC as in the case of the conventional optical disk. The first recording layer 33 has an information recording surface 34 on which information is recorded and the information recorded on the information recording surface 34 is displayed by incident light of a first wavelength. The first wavelength in this case is a wavelength of about 650 nm, and thus the first recording layer 33 corresponds to the information recording layer of the conventional digital versatile disc. Areas 34a and pits 34b which form a spiral track are provided on the information recording surface 34 of the first recording layer 33. Here, the track pitch of the first recording layer 33 is approximately 0.74 µm and the thickness (TJ between a light input surface 31a of the transparent substrate 31 and the information recording surface 34 of the first recording layer 33 preferably 0.6 mm.
    The partially translucent film 35 is formed on the information recording surface 34 of the first recording layer 33 and exhibits different transmitting powers depending on the wavelength of the incident light and therefore reflects the most light with the first wavelength and carries the most light with a second wavelength of, for example, 780 nm across for displaying an information signal recorded on the second recording layer 45.
    The intermediate layer 39 is a layer for joining and establishing a distance between the first recording layer 33 and the second recording layer 45 and transmits the incident light of the second wavelength which is through the partially transmissive film 35
    Hereby, adhesive layers 37 and 41 are formed between the partially translucent film 35 and the intermediate layer 39 and between the intermediate layer 39 and the second recording layer 45, respectively. The adhesive layers 37 and 41 are made of an ultraviolet curable resin and are formed by the spin coating method known per se.
    The second recording layer 45 has an information recording surface 46 and recorded information is displayed by the second wavelength light transmitted through the partially translucent film 35. The second recording layer corresponds to the information recording layer of the conventional compact disc (CD) . The second recording layer 45 is provided with regions 46a and pits 46b which form a spiral track in a manner similar to the first recording layer 33. Here, the track pitch of the second recording layer 45 is about 1.6 μτη and the thickness (T2) between light the surface 31a of the transparent substrate 31b enters and the information recording surface 46 of the second recording layer 45 is preferably 1.2 mm.
    The information recorded on the first recording layers 33 may be essentially the same as the information on the second recording layer 45. For example, when the optical disc of the present invention is used as a compatible audio disc, the first and second recording layers 33 and 45 are recorded, respectively. with the same audio information in different format. That is, the first recording layer 33 is recorded with super audio information with a sample rate of 96 kHz or higher and 5.1 channels Dolby AC3, and the second recording layer 45 is recorded with stereo audio information with a sample ratio of 44 , 1 kHz. Therefore, the optical disc is played either to produce stereo audio sound in a compact disc player or to produce super audio sound.
    The reflection film 43 is formed between the adhesive layer 41 and the information surface 46 of the second recording layer 45 and reflects light that is focused on the second recording layer 45. The reflection film 43 is formed of a material such as aluminum, aluminum alloys, copper or copper alloys.
    The protective layer 47 for protecting the second recording layer 45 is formed on the second recording layer 45 to prevent oxidation and damage to the second recording layer 45.
    Since the feature of the present invention depends on structures and characteristics of the partially translucent film 35, the partially translucent film 35 will now be discussed with reference to Figures 3-6.
    As shown in Fig. 3, it is preferable that the partially translucent film 35 has a reflectivity of more than about 25% with respect to a wavelength of 650 nm, and a reflectance of less than 18% with respect to a wavelength of 780 nm.
    This serves to avoid an adverse situation where the information recorded on the second recording layer 45 of the optical disc of the present invention that can be displayed in a CD / DVD compatible player using one light source with light having a shorter wavelength, for example light with a wavelength of 650 nm.
    To obtain the characteristics of the partially translucent film 35 as described above, the partially translucent film 35 consists of dielectric material as follows.
    The partially translucent film 35 may be formed from dielectric materials such as silicon (Si), silicon nitrides (SiNx), beryllium copper alloys, titanium dioxide (TiO2) or silicon dioxide (SiO2). Here, the reflectivity of the partially transmissive film 35 with respect to the light of the first wavelength and its transmissivity to light of the second wavelength can be determined by adjusting the thickness of the partially light transmissive film 35.
    In addition, the partially translucent film 35 can be constructed in the form of multi-layer dielectric layers laminated sequentially with a titanium dioxide (TiO2) layer, a magnesium fluoride (MgF2) layer and a titanium dioxide (TiO2) layer. Furthermore, the partially translucent film 35 preferably includes high refractive index dielectric layers ranging from about 2.0 to 2.9 and low refractive index dielectric layers ranging from about 1.3 to 2.0.
    When the high refractive index dielectric layers and the low refractive index dielectric layers are laminated successively from the side illuminated by light as described above, the reflectivity (R) on its interface is determined by the following equation:
    where nx and n2 are refractive indices of the respective high refractive index dielectric layers and low refractive index dielectric layers, d is the thickness of each high refractive index dielectric layer and λ is the wavelength of the incident light.
    Therefore, the reflectivity of the partially translucent film 35 with respect to the wavelength of the light is suitably determined by laminating the high refractive index dielectric layers and the low refractive index dielectric layers, as shown in FIG. 4. Here, each layer of the high refractive index dielectric layers and low refractive index dielectric layers may be made of a dielectric material such as silicon (Si), silicon nitrides (SiNx), beryllium copper alloys, titanium dioxide (TiO2) or silicon dioxide (SiO2).
    In addition, as shown in Fig. 5, the partially translucent film 35 may comprise a high refractive index first dielectric layer 35a, a low refractive index second dielectric layer 35b, and a high refractive index third dielectric layer 35c which successively are laminated from the side of the first recording layer 33 (Fig. 2). When each dielectric layer is formed from silicon nitride (SiN) and the refractive index of the high refractive index dielectric layers 35a and 35c is 2.88 and the refractive index of the low refractive index dielectric layer 35b is as shown in Fig. 5 , the characteristic reflectivity of the partially transmissive film 35 with respect to the light having the first wavelength of 650 nra and light having the second wavelength of 780 nm is shown in Fig. 6.
    Fig. 6 is a graph showing variations in the reflective powers of the first and second wavelengths relative to thickness variations of the first dielectric layer 35a when the thickness of the second dielectric layer 35b is 900 A and the thickness of the third dielectric layer 35c is 600 A is. As shown in Fig. 6, in the vicinity of a thickness of 1500 Å, the reflectivity of the light with the first wavelength of 650 nm is approximately 57% and the reflectivity of the light with the second wavelength of 780 nm is approximately 16%. %, and thus it is found that the partially translucent film 35 of this example exhibits a characteristic wavelength selectivity to transmit about 84% of the light of the second wavelength. Therefore, the reflectivity of the light beams of the first and second wavelengths can be selectively adjusted by adjusting the thickness or refractive index of each layer of the partially translucent film 35.
    Now, the display modes of the optical disc of the present invention will be explained when the information of the optical disc is displayed in, for example, a compact disc player and a digital versatile disc player, respectively.
    Referring to Fig. 7, when the optical disc is played in the digital versatile disc player, light 51 with a wavelength of 650 nm emitted from a light source is converged by an objective lens 53 with a numerical aperture of 0.6 and is focused on the first recording layer 33.
    Conversely, when referring to Fig. 8, the optical disc is played in the compact disc player, light 61 having a wavelength of 780 nm emitted from a light source is converged by an objective lens 63 having a numerical aperture of 0.45.
    The converged light 62 is transferred through the transparent substrate 31, the first recording layer 33, the partially translucent film 35 and the intermediate layer 39 and is focused on the second recording layer 45.
    As a result, the optical disc of the present invention can be played compatible in disc players of different format standards, for example, a compact disc player (CDP: compact disc player) or a digital versatile disc player (DVDP: digital versatile disc player) by recording information on the first and second recording layers 33 and 45 and forming between the two layers 33 and 45 the partially translucent film 35 exhibiting different transmissivity depending on the wavelength of hpf
    It will be apparent to those skilled in the art that numerous modifications are possible for an optical disk of the present invention without exceeding the scope and scope of the invention as defined in the following claims.
    权利要求:
    Claims (9)
    [1]
    An optical disc that can be played back compatible by optical disc players of different format standards, comprising: a transparent substrate for transmitting incident light; a first recording layer having an information recording surface on which an information signal is recorded and in which information recorded thereon is displayed by light of a first wavelength; a partially translucent film formed on one surface of the first recording layer, which exhibits a different transmissivity depending on the wavelength of the incident light and therefore reflects most of the light of the first wavelength and transmits most of the light of the second wavelength; an intermediate layer formed on one surface of the first recording layer and transmitting the light transmitted through the partially translucent film; a second recording layer having an information recording surface on which an information signal is recorded and in which information recorded thereon is reproduced by the light of the second wavelength transmitted through the partially translucent film; and a reflection film formed on the information recording surface of the second recording layer and reflecting the light focused on the second recording layer.
    [2]
    Optical disk according to claim 1, characterized in that the partially translucent film is made of a material or a combination of materials selected from the group consisting of silicon, silicon nitrides, beryllium copper alloys, titanium dioxide and silicon dioxide.
    [3]
    Optical disk according to claim 1, characterized in that the partially translucent film is a multilayer film successively laminated with a titanium dioxide layer, a magnesium fluoride layer and a titanium dioxide (TiO 2) layer.
    [4]
    Optical disk according to claim 1, characterized in that the partially translucent film comprises a dielectric layer with a high refractive index in the range of about 2.0 to 2.9 and a dielectric layer with a low refractive index in the range from 1.3 to 2.0.
    [5]
    Optical disc according to claim 4, characterized in that the each high refractive index dielectric layer and each low refractive index dielectric layer is made of a material or combination of materials selected from the group consisting of silicon, silicon nitride, beryllium copper alloys, titanium dioxide and silicon dioxide.
    [6]
    Optical disk according to claim 4, characterized in that the partially translucent film comprises a high refractive index dielectric layer, a low refractive index dielectric layer and a high refractive index dielectric layer successively viewed from the side of the first recording layer are laminated.
    [7]
    Optical disc according to claim 1, characterized in that the reflection film is made of a material or a combination of materials selected from the group consisting of aluminum, aluminum alloys, copper and copper alloys.
    [8]
    Optical disc according to claim 1, characterized in that the track pitch of the first recording layer is about 0.74 µm and the thickness between the transparent substrate and the information recording surface of the first recording layer is about 0.6 mm.
    [9]
    Optical disc according to claim 1, characterized in that the track pitch of the second recording layer is about 1.6 µm and the thickness between the transparent substrate and the information recording surface of the second recording layer is about 1.2 mm.
    类似技术:
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    同族专利:
    公开号 | 公开日
    KR19990011140A|1999-02-18|
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    GB9809623D0|1998-07-01|
    JPH1139710A|1999-02-12|
    GB2327525A|1999-01-27|
    CN1206183A|1999-01-27|
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    KR20020074685A|2001-03-21|2002-10-04|한국전자통신연구원|Optical storage medium based on the luminescence from the crystalline semiconductor and optical storage/reading device and method by using photon absorption|
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    JP2007004856A|2005-06-22|2007-01-11|Sony Corp|Information processing device and method, and computer program|
    JP4305776B2|2006-10-11|2009-07-29|ソニー株式会社|Optical disc apparatus and focus position control method|
    法律状态:
    1999-04-01| AD1B| A search report has been drawn up|
    1999-04-01| RD2N| Patents in respect of which a decision has been taken or a report has been made (novelty report)|Effective date: 19990217 |
    优先权:
    申请号 | 申请日 | 专利标题
    KR1019970034111A|KR19990011140A|1997-07-21|1997-07-21|Optical disc|
    KR19970034111|1997-07-21|
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