Information-recording medium, method for manufacturing same, method for recording and playbacking information and method for erasing information

Abstract

A recording film has recording tracks that record information and separating regions that separate neighboring recording tracks. A recording film reflects light when performing recording, playback, and erasing of information. A protective film has a pattern of surface unevenness that corresponds with the recording tracks and separating regions, and has a thickness at a recording track whereby there is a change in the reflectivity of the reflective film depending upon whether or not there is information recorded, and a thickness at the separating regions such that the reflectivity does not depend upon whether information is recorded.

What is claimed is:  
     
         1 . An information recording medium comprising; 
 a recording film that records information;    a reflective film, which is formed on said recording film, and which reflects light so as to record information on said recording film, play back information therefrom, or erase information;    and a protective film that is formed between said recording film and said reflective film, and which has a configuration so that the reflectivity of a part corresponding to said recording region of said information-recording medium will be differ from each other depending upon whether or not said recording film of said recording region has information recorded thereon, while said reflectivity of a part corresponding to said separating region of said information-recording medium separating adjacently arranged recording regions from each other, is substantially uniform to each other, regardless the fact that whether or not said recording film of said separating region has information recorded thereon.    
     
     
         2 . An information-recording medium according to  claim 1 , wherein said protective film has a thickness so that in said recording region, said reflectivity of a part corresponding to said recording region of said information-recording medium will be differ from each other depending upon whether or not said recording film of said recording region has information recorded thereon, while said reflectivity of a part corresponding to said separating region of said information-recording medium is substantially uniform to each other, regardless the fact that whether or not said recording film of said separating region has information recorded thereon.  
     
     
         3 . An information-recording medium according to  claim 2 , wherein said protective film has a convex-concave configuration corresponding to said recording region and said separating region, respectively.  
     
     
         4 . An information-recording medium according to either  claim 3 , wherein the surface of said recording film is flat, and further wherein said reflective film has the convex-concave configuration that is substantially the same as that of said protective film.  
     
     
         5 . An information-recording medium according to  claim 3 , wherein said recording film has the convex-concave configuration that is substantially the same as that of said protective film and wherein said protective film fills this pattern of surface unevenness and has a flat surface, the surface of said reflective film being flat.  
     
     
         6 . An information-recording medium according to  claim 2 , wherein the thickness of said protective film is established in accordance with at least one parameter of the group consisting of the wavelength of the light used for play back information, the material of the recording film, the material of the protective film, and the material of the reflective film.  
     
     
         7 . An information-recording medium according to  claim 3 , wherein said protective film has a thickness so that in a case of a light having a first wavelength being used, the reflectivity of a concaved part of said convex-concave configuration will be uniform regardless the fact that whether or not said recording film has information recorded thereon, while the reflectivity of a convexed part thereof will differ from each other, depending upon whether or not said recording film has information recorded thereon, further in a case of a light having a second wavelength being used, the reflectivity of a convexed part of said convex-concave configuration will be uniform, regardless the fact that whether or not said recording film has information recorded thereon, while the reflectivity of a concaved part thereof will differ from each other, depending upon whether or not said recording film has information recorded thereon.  
     
     
         8 . An information-recording medium which can record information onto circular tracks, said medium comprises a plurality of first tracks eccentrically arranged to each other and a plurality of second tracks each being eccentrically arranged to each other and between said first tracks adjacently arranged, wherein said first tracks has different reflectivities from each other corresponding to the fact that whether or not a part of said first track has information recorded thereon, while said second tracks has substantially uniform reflectivity, regardless the fact that whether or not said second tracks has information recorded thereon, with respect to said light having said first wavelength, while with respect rho said light having said second wavelength which is different from said first wavelength, said second tracks has different reflectivities from each other corresponding to the fact that whether or not a part of said second track has information recorded thereon, while said first tracks has substantially uniform reflectivity, regardless the fact that whether or not said first tracks has information recorded thereon, and further wherein said second tracks serving as a separating region for separating said adjacently arranged recording films which record information thereon, from each other, with respect to said first tracks and further wherein said first tracks serving as said separating region with respect to said second tracks.  
     
     
         9 . An information-recording medium according to  claim 8 , wherein said first and second tracks comprise a recording film which records information thereon, a protective film and a reflective film reflects light, and further wherein said protective film has a thickness so that with respect to a light having a first wavelength, said first tracks has different reflectivities from each other corresponding to the fact that whether or not a part of said first track has information recorded thereon, while said second tracks has substantially uniform reflectivity, regardless the fact that whether Or not said second tracks has information recorded thereon, further wherein, with respect to said light having said second wavelength which is different from said first wavelength, said second tracks has different reflectivities from each other corresponding to the fact that whether or not a part of said second track has information recorded thereon, while said first tracks has substantially uniform reflectivity, regardless the fact that whether or not said first tracks has information recorded thereon.  
     
     
         10 . A method for manufacturing an information-recording medium comprising: 
 a step of forming a recording film which record information thereon;    a step of forming a reflective film which reflects light so as to record information on said recording film, play back information therefrom, or erase information, on said recording film; and    a step of forming a protective film between said recording film and said reflective film, said protective film having a thickness so that in said recording region, a reflectivity of a part corresponding to a recording region of an information-recording medium will be differ from each other depending upon whether or not said recording film of said recording region has information recorded thereon, while said reflectivity of a part corresponding to said separating region separating said adjacently arranged recording regions from each other, of said information recording medium is substantially uniform to each other, regardless the fact that whether or not said recording film of said separating region has information recorded thereon.    
     
     
         11 . A method for manufacturing an information-recording medium according to  claim 10 , wherein said recording film forming step being provided with a process for forming said recording film surface thereof being flat; said protective film forming step being provided with a process for forming said protective film having a convex-concave configuration corresponding to said recording region and said separating region, respectively; and said reflective film forming step being provided with a process for forming aid reflective film having a convex-concave configuration being substantially identical with that of said protective film.  
     
     
         12 . A method for manufacturing an information-recording medium according to  claim 11 , wherein said protective film forming step further comprises a step for forming a first protective film on said recording film and which having a flat surface and a step for forming a second protective film having said convex-concave configuration by forming a photoresist film on said protective film and by patterning thereof.  
     
     
         13 . A method for manufacturing an information-recording medium according to  claim 10 , wherein said recording film forming step being provided with a step for forming said recording film having a convex-concave configuration corresponding to said recording region and said separating region, respectively, said protective film forming step being provided with a step for forming said protective film which fills said convex-concave configuration so as to reduce said unevenness surface flat, and further, said reflective film forming step being provided with a step for forming said reflective film having a flat surface.  
     
     
         14 . A method for manufacturing an information-recording medium comprising: 
 a step of forming a recording film having a flat surface;    a step of forming a first protective film on said recording film;    a step of forming a second protective film having a convex-concave configuration corresponding to recording region which record information thereon and separating regions Which separate said recording regions adjacently arranged from each other;    a step of forming a reflective film on said second protective film and along said convex-concave configuration formed on said second protective film; and    a step of adhering a surface of said first protective film with a surface of said reflective film to each other.    
     
     
         15 . A method for manufacturing an information-recording medium comprising; 
 a step of forming a recording film having a convex-concave configuration corresponding to a recording region which records information thereon and a separating region separating said adjacently arranged recording regions from each other;    a step of forming a first protective film along said convex-concave configuration formed on said recording film:    a step of forming a second protective film having a flat surface;    a step of forming a reflective film on said second protective film; and    a step of adhering a surface of said first protective film with a surface of said reflective film to each other.    
     
     
         16 . A method for recording and playbacking information by radiating light onto an information recording medium so that information is recorded on or playbacked from said information recording medium, wherein said information recording medium comprising: 
 a recording film that records information;    a reflective film, which is formed on said recording film, and which reflects light so as to record information on said recording film, to play back information therefrom, or to erase information; and    a protective film having a convex-concave configuration, that is formed between said recording film and said reflective film having a thickness so that in a case of a light having a first wavelength being used, the reflectivity of a concaved part of said convex-concave configuration will be uniform regardless the fact that whether or not said recording film has information recorded thereon, while the reflectivity of a convexed part thereof will differ from each other, depending upon whether or not said recording film has information recorded thereon, further in a case of a light having a second wavelength being used, the reflectivity of a convexed part of said convex-concave configuration will be uniform, regardless the fact that whether or not said recording film has information recorded thereon, while the reflectivity of a concaved part thereof will differ from each other, depending upon whether or not said recording film has information recorded thereon; wherein said method for recording and playbacking information is performed so that said light having a first wavelength is used for recording information onto or for palybacking information from a part corresponding to a convexed portion of said convex-concave configuration formed in said protective film, while said light having a second wavelength is used for -recording information onto or for palybacking information from a part corresponding to a concaved portion thereof.    
     
     
         17 . A method for erasing information by radiating light onto an information recording medium so that information is erased from said information recording medium, wherein said information recording medium comprising: 
 a recording film that records information;    a reflective film, which is formed on said recording film, and which reflects light so as to erase information from said information recording medium; and;    recording film, to play back information therefrom, or to erase information; and    a protective film having a convex-concave configuration, that is formed between said recording film and said reflective film having a thickness so that the reflectivity of a concaved part of said convex-concave configuration will be substantially uniform regardless the fact that whether or not said recording film has information recorded thereon, while in a case of a light having a second wavelength being used, the reflectivity of a convexed part of said convex-concave configuration will be substantially uniform, regardless the fact that whether or not said recording film has information recorded thereon;    wherein said method for erasing information is performed so that said light having a first wavelength is used for erasing information from a part corresponding to a concaved portion of said convex-concave configuration formed in said protective film, while said light having a second wavelength is used for erasing from a part corresponding to a convexed portion thereof.