JP2005339795A - Optical information recording medium, reproducing method for optical information recording medium, and optical information reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium with which accurate and sure reproduction is possible even if information is recorded to high density, a recording method using the same, a reproducing method, reproducing device and a recording device. <P>SOLUTION: The optical information recording medium 1 has a substrate 12 formed with pits and/or grooves of rugged shapes corresponding to the recorded information and is used for optically reproducing the information by irradiation with a light beam or the optical recording medium has a recording layer, wherein the optical information recording medium is provided with a temperature sensitive layer changing the transmittance of the irradiation light beam according to elevation of the temperature by irradiation with the light beam, and a light absorption layer 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical information recording medium, and a recording method, a reproducing method, an optical information reproducing apparatus, and an optical information recording apparatus using the same. More specifically, the present invention relates to an optical information recording medium such as an optical disc that optically reproduces or records / reproduces information optically by using a light beam such as a laser beam. And an optical information recording medium whose recording density is improved by providing a layer for assisting temperature change of the layer, and a recording method, reproducing method, optical information reproducing apparatus, and optical information recording apparatus using the same Is.

  With the development of digitalization in the information society, recording / reproduction at high density is desired on a writable medium.

  In order to improve the recording capacity, various medium configurations have been tried as so-called writable optical recording media, and in order to realize high-density recording / reproduction, for example, i) Shortening the wavelength of the laser light, ii) increasing the objective lens NA (aperture) focused on the optical information recording medium, iii) making the recording layer of the optical information recording medium multilayer, iv) optical information Attempts have been made to form a mask layer (also referred to as an optical shutter layer) that blocks a part of the light having the original spot size on the recording medium to substantially reduce the light spot diameter of the laser light.

  Methods for reducing the substantial spot diameter by forming a mask layer on an optical information recording medium are described in, for example, Patent Document 1, Patent Document 2, and the like.

  Specifically, Patent Document 1 discloses an optical disc apparatus that performs recording and reproduction using a change in reflectance by uneven pits formed on an optical disc substrate, on the medium layer on which a signal is recorded ( The laser beam is emitted from the objective lens on the disk surface to the side where the laser beam is emitted) at room temperature, and the laser beam is not absorbed by the temperature rise due to the reproduction laser power. It is disclosed to form a temperature-dependent optical shutter layer that absorbs reproduction laser light.

  Further, in Patent Document 1, in an optical disc apparatus that records and reproduces information using a change in reflectance due to a phase change of a recording material, a laser beam is emitted from an objective lens on the disc surface (from an objective lens on the disc surface). On the side where the laser beam is emitted), the laser beam is absorbed at room temperature, the laser beam is not absorbed by the temperature rise due to the power of the laser beam, and the laser beam is again absorbed by the temperature drop after passing through the beam. Forming a temperature dependent optical shutter layer is also disclosed.

  Further, in Patent Document 2, in an optical recording medium having a recording film on a substrate, an optical shutter layer is provided at a position before the reading light or recording light is incident on the recording film. It is in a colored state that does not transmit the light before being irradiated, and the thermochromic substance that becomes light transmissive as the temperature of the central part of the irradiated part rises due to irradiation of the reading light and becomes partially transparent, as a main component An optical recording medium containing is disclosed.

In these methods, in an optical information recording medium having a concavo-convex pit or recording film on a substrate, a mask layer is provided on the light incident side of the pit or recording film. This mask layer is usually formed of a thermochromic material or a phase change material. Since a large amount of light such as readout light is incident on the central portion of the irradiated portion in the mask layer, the temperature rises due to light irradiation. Therefore, the central part of the irradiated part in the mask layer changes optically or thermally, and is partially decolored to become light transmissive. On the other hand, the outer peripheral part of the irradiated part, where the incident light is weak, and the part where no light is incident, have little or no temperature rise due to light irradiation, so the light transmittance is reduced and the light is blocked. Is done. As a result, the substantial spot size becomes the size of the central portion of the irradiated portion, and the substantial spot size can be reduced. That is, the mask layer transmits light only in a portion where the light intensity distribution is high, thereby substantially reducing the spot diameter of incident light and enabling recording and reproduction of small pits. As a result, high-density recording / reproduction with respect to the optical information recording medium becomes possible. In the rotated optical disc, the central portion is an upstream portion (the high temperature portion 33a in FIG. 13) of the reproduction beam spot 33 in FIG.
Japanese Patent Laid-Open No. 5-12673 (Publication date: January 22, 1993) Japanese Patent Laid-Open No. 5-12715 (Publication date: January 22, 1993)

  Substances such as thermochromic materials and phase change materials forming the mask layer (optical shutter layer) of Patent Document 1 and Patent Document 2 exhibit a mask effect by melting when the temperature is raised to a certain temperature or higher. Is. The melted substance has high fluidity, and its initial composition and shape are likely to change. For this reason, in an optical information recording medium having a mask layer that exhibits a mask effect when the temperature is raised to a certain temperature or higher, the mask effect is gradually increased due to deviations in the composition and shape of the mask layer when repeated recording and reproduction are performed. There is a problem that the mask effect is almost eliminated by repeating the process several thousand times. Therefore, the conventional optical information recording medium has insufficient durability.

  Patent Document 1 states that “this temperature-dependent light transmittance variable medium is formed of a polymer material or an organic material, for example, and is made of a material having a high light transmittance in a high temperature region, for example. is there. The change in the transmittance may be due to a change in the regularity of the molecular arrangement as in the case of a liquid crystal material, as the light transmittance increases as the material melts. Further, like the phase change material, the light transmittance may be changed by crystallization of, for example, chalcogenide adhered in an amorphous state by heating and cooling. Is described. However, in this description, it cannot be said that an example of a material having high light transmittance in a high temperature region is specifically described in the text. Therefore, the invention of Patent Document 1 cannot be realized by those skilled in the art based on the description of Patent Document 1 and the technical common sense at the time of publication of Patent Document 1.

  The present invention has been made in view of the problem that high-density recording / reproduction is desired. The purpose of the present invention is to provide optical information capable of accurate and reliable reproduction even when information is recorded at high density. It is an object to provide a recording medium, and a recording method, a reproducing method, a reproducing apparatus, and a recording apparatus using the recording medium.

  In order to solve the above problems, an optical information recording medium of the present invention is an optical information recording medium for reproducing recorded information by irradiation with a light beam. It has a temperature-sensitive layer in which the rate and / or transmittance changes, and a light-absorbing layer that changes the temperature of the temperature-sensitive layer.

  According to the above configuration, when the reproducing light beam is irradiated, the transmittance changes in the temperature-sensitive layer where the temperature is increased by the light beam irradiation, that is, the transmittance is decreased or increased, and there is no other temperature increase and the temperature is low. Then, the transmittance is maintained. Further, the temperature of the temperature sensitive layer varies depending on the light absorption layer in addition to the light beam irradiation. For example, when the light absorption layer is a material that converts light into heat, the light absorption layer absorbs a light beam for reproduction and converts it into heat. The heat converted in the light absorption layer moves to the temperature sensitive layer. As a result, the temperature of the temperature sensitive layer that has risen due to light beam irradiation is further increased. Therefore, the transmittance of the portion is further lowered or increased.

  As a result, it is possible to reproduce information based on light transmitted through the high temperature portion or the low temperature portion of the temperature sensitive layer. As a result, it is possible to selectively perform reproduction in an area having a size smaller than the spot size of the reproduction light beam. Furthermore, since the light absorption layer assists the temperature change of the temperature sensitive layer, even when irradiated with a light beam of the same power as the conventional one, information can be reproduced accurately and reliably compared to those without the light absorption layer. A possible optical information recording medium can be provided. Therefore, even a pit smaller than the readout spot size of the optical system that could not be read by the conventional method that does not use the temperature sensitive layer and the light absorption layer can be read with high signal intensity characteristics.

  An optical information recording medium for reproducing the recorded information by irradiating with a light beam has a concave-convex pit formed on the substrate from the beginning, such as a CD-ROM, for example. This is a medium that functions as a dedicated ROM). As a typical example of the optical information recording medium having the above-described structure, there is provided a substrate on which concave and convex pits and / or grooves corresponding to recorded information are formed, and light for optically reproducing the information by irradiation with a light beam. Examples of the information recording medium include a configuration having a temperature sensitive layer in which the transmittance of the irradiated light beam changes according to the temperature rise caused by the light beam irradiation. If a substrate having concave and convex pits and / or grooves is not used, it is difficult to realize an optical information recording medium having the above-described configuration. Alternatively, a method of forming pits and recording / reproducing information thereafter (although there is no such practical example in the past) can be considered.

  In order to solve the above problems, an information recording medium of the present invention is an optical information recording medium for recording information by irradiation with a light beam and reproducing the information by irradiation with a light beam. It is characterized by having a temperature sensitive layer whose reflectance and / or transmittance changes based on a change in temperature due to irradiation, and a light absorbing layer which changes the temperature of the temperature sensitive layer.

  According to the above configuration, when the recording light beam is irradiated, the transmittance changes, that is, decreases or increases in the temperature-sensitive layer where the temperature is increased by the light beam irradiation, and other portions where the temperature is low without any temperature increase. Then, the transmittance is maintained. Further, the temperature of the temperature sensitive layer varies depending on the light absorption layer in addition to the light beam irradiation. For example, when the light absorption layer is a material that converts light into heat, the light absorption layer absorbs a light beam for reproduction and converts it into heat. The heat converted in the light absorption layer moves to the temperature sensitive layer. As a result, the temperature of the temperature sensitive layer that has risen due to light beam irradiation is further increased. Therefore, the transmittance of the portion is further lowered or increased.

  Thereby, it is possible to record information based on light transmitted through the high temperature portion or the low temperature portion of the temperature sensitive layer. Recording can be performed selectively in an area having a size smaller than the spot size of the recording light beam. In addition, since the light absorption layer assists the temperature change of the temperature sensitive layer, even when irradiated with a light beam of the same power as conventional, information recording can be performed accurately and reliably compared to those without the light absorption layer. A possible optical information recording medium can be provided. Therefore, even a mark smaller than the readout spot size of the optical system that could not be read by the conventional method that does not use the temperature sensitive layer and the light absorption layer can be read with high signal intensity characteristics. Further, according to the above configuration, when information is recorded on the recording layer, it is possible to selectively perform reproduction in an area having a size smaller than the spot size of the irradiation light beam, as in the above configuration. As a result, compared with an optical information recording medium that does not have a temperature sensitive layer and a light absorbing layer, an optical information recording medium that can accurately and reliably reproduce information even if information is recorded at a high density. Can be provided.

  An optical information recording medium for recording the information and reproducing the information by irradiation with a light beam is a medium functioning as a recording / reproducing RAM (phase change medium, magneto-optical (MO) recording medium, etc.). A write-once medium (using a dye, an inorganic film, etc.). As a typical example of the optical information recording medium having the above-described structure, an optical information recording medium that includes a recording layer for optically recording information and optically reproduces the information by irradiation with a light beam. Examples include a structure having a temperature sensitive layer in which the transmittance of the irradiation light beam changes according to the temperature rise due to irradiation.

  It can also be said that the light absorption layer changes the light absorption amount (that is, reflectance and / or transmittance) of the temperature sensitive layer by absorbing the light beam. In addition, as the temperature sensitive layer whose reflectance changes based on a change in temperature, a layer made of a material whose refractive index (real part / imaginary part) changes in temperature, such as ZnO (zinc oxide), and an Al (aluminum) film A structure having a reflective layer such as, for example, is conceivable. In this case, the light absorption layer is preferably formed between the layer made of the material whose refractive index changes in temperature and the reflective layer.

  The temperature sensitive layer has a change in reflectance and / or transmittance based on interference of the irradiated light beam between reflected light on one surface of the temperature sensitive layer and reflected light on the other surface. Is preferred. Further, the temperature sensitive layer has a transmittance lowering region accompanying absorption on the short wavelength side at room temperature (from the vicinity of the absorption wavelength on the short wavelength side to the wavelength of the irradiation light beam most on the longer wavelength side than the reproduction light beam wavelength). The region near the maximum value of the near transmittance is shifted to the long wavelength side or the short wavelength side as the temperature sensitive layer increases, and the spectral transmittance and / or the spectral reflectance at the wavelength of the reproduction light beam. Is preferably changed. Further, it is preferable that the spectral reflectance characteristics of the temperature sensitive layer have a minimum value near the wavelength of the light beam due to the optical interference effect between the reflected light on one surface and the reflected light on the other surface.

  According to each of the above configurations, optical interference occurs between the reflected light on one surface of the temperature sensitive layer and the reflected light on the other surface, and using this optical interference effect, the transmittance characteristics of the temperature sensitive layer and By controlling the temperature change of the reflectance characteristic, it is possible to increase the transmittance and / or reflectance change (modulation factor) due to the temperature change. As a result, the masking effect by the temperature sensitive layer is further increased, and reproduction with a diameter smaller than the spot diameter of the irradiation light beam can be performed more accurately and reliably.

  If the temperature-sensitive layer has a reduced or increased transmittance of the light beam irradiated as the temperature rises, the transmittance of the temperature-sensitive layer heated to a high temperature is reduced or increased. The reproduction resolution can be improved.

As described above, the mask layers of Patent Documents 1 and 2 have a problem that the mask effect is lowered when repeated recording and reproduction are performed. On the other hand, in the said structure, the temperature sensitive layer which reduces or raises the transmittance | permeability in a high temperature part is used. The temperature-sensitive layer can be made of a material that does not melt due to temperature rise during recording or playback.
Even if repetitive recording and reproduction are performed, the mask effect does not decrease. Therefore, an optical information recording medium having excellent durability can be provided.

  The temperature-sensitive layer preferably contains a metal oxide, particularly zinc oxide, whose reflectance and / or transmittance changes as the temperature rises.

  According to the above configuration, since the temperature sensitive layer can be prevented from melting due to a temperature rise during recording and reproduction, an optical information recording medium having excellent durability that does not deteriorate the mask effect even when repeated recording and reproduction is performed. Can be provided.

  The light absorption layer is preferably formed on the side opposite to the light beam irradiation surface in the temperature sensitive layer. In other words, the light absorption layer is preferably provided on the back side of the temperature sensitive layer. The light absorption layer preferably includes a phase change material, a magneto-optical material, or an alloy thereof, and includes Si, Ge, AgInSbTe, GeSbTe, TbFeCo, DyFeCo, GdFeCo, or an alloy composed of two or more thereof. More preferably, Si is included. The temperature sensitive layer and the light absorbing layer are preferably adjacent to each other.

  According to each of the above configurations, a light beam that is irradiated effectively can be converted into heat, so that the temperature of the temperature-sensitive layer can be further increased due to the light beam irradiation. . That is, the temperature rise of the temperature sensitive layer due to the light beam irradiation can be further increased. As a result, the transmittance and / or reflectivity of the portion where the temperature has risen can be greatly changed, so that it is possible to provide an optical information recording medium capable of reproducing information more accurately and reliably.

  Further, in an optical information recording medium including a recording layer for optically recording information, it is preferable that the temperature sensitive layer is provided on the back side of the surface of the recording layer on which the light beam is irradiated. According to the above configuration, the temperature sensitive layer is provided on the back side of the surface of the recording layer on which the light beam is irradiated, so that the mask layer is provided on the light incident side of the recording layer. There are the following advantages over the configuration. That is, in the optical information recording media of Patent Documents 1 and 2 having a recording film on the substrate, since the mask layer is formed on the light incident side of the recording film, at least one of the total amount of light reaching the recording layer. Part is absorbed by the mask layer. Therefore, high signal quality cannot be obtained due to a decrease in recording sensitivity or an increase in reproduction noise. On the other hand, by providing a temperature sensitive layer on the back side of the recording layer, it is possible to easily raise the temperature of the temperature sensitive layer using optical interference. As a result, it is possible to reproduce with lower laser power and to realize an optical information recording medium with high reproduction sensitivity.

  As described above, the optical information recording medium of the present invention uses the change in reflectance and / or transmittance corresponding to the change in the temperature of the temperature sensitive layer due to the light beam and the light absorption layer to reproduce light. It is characterized in that a minute recording mark having a beam diffraction limit or less can be reproduced.

  In the reproducing method of the optical information recording medium of the present invention, the optical information recording medium is irradiated with a light beam so that a high temperature portion and a low temperature portion are generated in a light beam spot in the temperature sensitive layer, and the temperature sensitive layer is obtained. In addition, the transmittance at the high temperature portion is reduced, the temperature of the high temperature portion is further heated by the light absorption layer, and information is reproduced based on the light transmitted through the low temperature portion of the temperature sensitive layer. Further, in the reproducing method of the optical information recording medium of the present invention, the optical information recording medium is irradiated with a light beam so that a high temperature portion and a low temperature portion are generated in the light beam spot in the temperature sensitive layer, and the temperature is It may be a method of increasing the transmittance in the high temperature portion of the sensitive layer, further heating the temperature of the high temperature portion by the light absorbing layer, and reproducing the information based on the light transmitted through the high temperature portion of the temperature sensitive layer. .

  According to each of the above methods, information is reproduced based on light transmitted through the low-temperature part or the high-temperature part of the temperature-sensitive layer, so that reproduction can be performed selectively in a region having a size smaller than the spot size of the light beam for reproduction. It can be carried out. As a result, information can be accurately and reliably reproduced from an optical information recording medium on which information is recorded at high density.

  In the reproduction method according to the present invention, it is preferable to control the reproduction power so that the super-resolution effect is optimized (maximum signal amplitude). That is, since the irradiation power control of the light beam at the time of signal reproduction has an optimum value for the reproduction power intensity, for example, the reproduction power at which the C / N ratio or the reproduction signal amplitude becomes the maximum value is obtained in advance and the maximum value is obtained. It is preferable to reproduce while feedback.

  In the recording method of the optical information recording medium of the present invention, the optical information recording medium is irradiated with a light beam so that a high-temperature portion and a low-temperature portion are generated in the light beam spot in the temperature-sensitive layer. It is characterized by lowering the transmittance in the high temperature part of the sensitive layer, further heating the temperature of the high temperature part by the light absorbing layer, and heating the recording layer by the light transmitted through the low temperature part of the temperature sensitive layer. . Further, the optical information recording medium recording method of the present invention irradiates the optical information recording medium with a light beam so that a high temperature portion and a low temperature portion are generated in the light beam spot in the temperature sensitive layer. A method of increasing the transmittance of the temperature sensitive layer at a high temperature portion, further heating the temperature of the high temperature portion by a light absorbing layer, and heating the recording layer by light transmitted through the high temperature portion of the temperature sensitive layer. Also good.

  According to each of the above methods, information is reproduced based on light transmitted through the low-temperature part or the high-temperature part of the temperature-sensitive layer, so that reproduction can be performed selectively in a region having a size smaller than the spot size of the light beam for reproduction. It can be carried out. As a result, information can be recorded accurately and reliably from an optical information recording medium on which information is recorded at high density.

  The reproducing method of the optical information recording medium of the present invention is a reproducing method of the optical information recording medium, wherein a minute recording mark having a diffraction light beam below the reproduction limit is reproduced using the temperature sensitive layer and the light absorbing layer. It is characterized by doing. The optical information reproducing apparatus of the present invention is characterized by reproducing a minute recording mark having a diffraction light beam below the diffraction limit using the optical information recording medium and the optical information reproducing method.

  According to the above-described invention, it is natural that information on a minute recording mark below the diffraction limit of the reproduction light beam can be reproduced.

  The recording method of the optical information recording medium of the present invention is the recording method of the optical information recording medium, wherein at least the temperature sensitive layer and the light absorbing layer are used, and the minute recording mark below the diffraction limit of the reproduction light beam It is characterized by recording. The optical information recording apparatus of the present invention is characterized by recording information on a minute recording mark below the diffraction limit of a light beam using the optical information recording medium and the recording method.

  According to the above-described invention, it is natural that information on a minute recording mark below the diffraction limit of the reproduction light beam can be recorded.

  As described above, the optical information recording medium of the present invention includes a substrate on which concave and convex pits and / or grooves corresponding to recorded information are formed, and for optically reproducing the information by irradiation with a light beam. The optical information recording medium has a temperature-sensitive layer in which the transmittance of the irradiated light beam changes according to the temperature rise caused by the light beam irradiation, and a light-absorbing layer that assists in heating the temperature-sensitive layer.

  According to the above configuration, reproduction can be performed selectively. Reproduction can be selectively performed in a low transmittance region (high temperature region or low temperature region) having a size smaller than the spot size of the light beam for reproduction. As a result, it is possible to provide an optical information recording medium that can be accurately and reliably reproduced even if information is recorded at high density. Therefore, even a pit smaller than the readout spot size of the optical system that could not be read by the conventional method that does not use the temperature sensitive layer can be read with high signal intensity characteristics. In addition, the presence of the light absorption layer makes it easy to heat the temperature sensitive layer, thereby improving the reproduction power sensitivity.

  Further, as described above, the optical information recording medium of the present invention includes a recording layer for optically recording information by irradiation with a light beam, and for optically reproducing the information by irradiation with the light beam. The optical information recording medium has a temperature-sensitive layer in which the transmittance of the irradiated light beam changes according to the temperature rise caused by the light beam irradiation, and a light-absorbing layer that assists in heating the temperature-sensitive layer.

  According to the above configuration, it is possible to selectively perform recording in a region having a size smaller than the spot size of the recording light beam. As a result, it is possible to provide an optical information recording medium capable of recording information with high density and accuracy with high accuracy as compared with an optical information recording medium having no temperature sensitive layer. Further, according to the above configuration, when information is recorded on the recording layer, it is possible to selectively perform reproduction in an area having a size smaller than the spot size of the irradiation light beam, as in the above configuration. In addition, the presence of the light absorption layer makes it easy to heat the temperature sensitive layer, thereby improving the reproduction power sensitivity. As a result, the above configuration can provide an optical information recording medium that can be accurately and reliably reproduced even when information is recorded at a high density, compared to an optical information recording medium that does not have a temperature sensitive layer. The light absorbing layer can lower the reproduction power, resulting in an improvement in reproduction resolution and higher density than conventional.

  As described above, the optical information recording medium reproducing method of the present invention irradiates the optical information recording medium with a light beam so that a high temperature portion and a low temperature portion are generated in the light beam spot in the temperature sensitive layer. In this method, the transmittance in the high temperature portion of the temperature sensitive layer is reduced, and information is reproduced based on the light transmitted through the low temperature portion of the temperature sensitive layer. In addition, as described above, the optical information recording medium reproducing method of the present invention has a light beam so that a high-temperature portion and a low-temperature portion are generated in the light beam spot in the temperature-sensitive layer with respect to the optical information recording medium. , The transmittance at the high temperature portion of the temperature sensitive layer is increased, and information is reproduced based on the light transmitted through the high temperature portion of the temperature sensitive layer.

  According to each of the above methods, information is reproduced based on the light transmitted through the low temperature portion or the high temperature portion of the temperature sensitive layer, thereby selectively reproducing in a region having a size smaller than the spot size of the light beam for reproduction. It can be carried out. As a result, the above configuration has an effect that information can be accurately and reliably reproduced from an optical information recording medium on which information is recorded at high density.

  As described above, the optical information recording medium recording method of the present invention irradiates the optical information recording medium with a light beam so that a high temperature portion and a low temperature portion are generated in the light beam spot in the temperature sensitive layer. In this way, the transmittance in the high temperature portion of the temperature sensitive layer is reduced, and the recording layer is heated by the light transmitted through the low temperature portion of the temperature sensitive layer. In addition, as described above, the optical information recording medium recording method of the present invention has a light beam so that a high-temperature portion and a low-temperature portion are generated in the light beam spot in the temperature-sensitive layer with respect to the optical information recording medium. Is used to increase the transmittance at the high temperature portion of the temperature sensitive layer and heat the recording layer with light transmitted through the high temperature portion of the temperature sensitive layer.

  According to each of the above methods, the recording layer is heated by the light transmitted through the low-temperature part or the high-temperature part of the temperature-sensitive layer, thereby selectively recording in an area having a size smaller than the spot size of the recording light beam. It can be carried out. As a result, the above configuration has an effect that information can be recorded on the recording layer with high density and accuracy. In addition, the presence of the light absorption layer makes it easy to heat the temperature sensitive layer, thereby improving the reproduction power sensitivity.

  The reproducing method of the optical information recording medium of the present invention is a reproducing method of the optical information recording medium, wherein a minute recording mark having a diffraction light beam below the reproduction limit is reproduced using the temperature sensitive layer and the light absorbing layer. It is a method to do. The optical information reproducing apparatus of the present invention is configured to reproduce a minute recording mark below the diffraction limit of the reproducing light beam using the optical information recording medium and the optical information reproducing method.

  According to these, it is possible to reproduce the information of the minute recording mark below the diffraction limit of the reproducing light beam.

  The recording method of the optical information recording medium of the present invention is the recording method of the optical information recording medium, wherein at least the temperature sensitive layer and the light absorbing layer are used, and the minute recording mark below the diffraction limit of the reproduction light beam Is a method of recording. The optical information recording apparatus of the present invention is configured to record information on a minute recording mark below the diffraction limit of a light beam using the optical information recording medium and the recording method.

  According to these, it is possible to record information on a minute recording mark below the diffraction limit of the reproduction light beam.

[Embodiment 1]
Hereinafter, an embodiment of an optical information recording medium of the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1, 3, 22, and 23, the optical information recording medium of the present embodiment is a reproduction-only optical information recording medium 1a, 1c, and 1d, and a reproduction beam 30 that is a reproduction light beam. The transparent resin layer 11, the temperature sensitive reflection layer 13, and the substrate 12 are formed in this order from the side on which the light enters. The temperature-sensitive reflection layer 13 includes a temperature-sensitive layer 21, a light absorption layer 22, a reflection layer 23 and / or a heat insulation layer 24. That is, the temperature sensitive reflection layer 13 of the optical information recording medium 1a is composed of the temperature sensitive layer 21, the light absorption layer 22, and the reflection layer 23. The temperature sensitive reflection layer 13 of the information recording medium 1c is the temperature sensitive layer 21. The temperature-sensitive reflective layer 13 of the information recording medium 1d is composed of a temperature-sensitive layer 21, a light-absorbing layer 22, a reflective layer 23, and a heat-insulating layer 24.

  As described above, the optical information recording media 1a, 1c, and 1d have the temperature-sensitive reflective layer 13 formed on the substrate 12 and the transparent resin layer 11 formed thereon. The reproduction beam 30 is incident on the inner surface of the substrate 12 (the surface on the temperature sensitive reflective layer 13 side) through the temperature sensitive reflective layer 13.

  As will be described later, since the temperature sensitive layer 21 can be formed of an oxide and a stable substance, the structure without the transparent resin layer 11 as shown in FIGS. 2, 24, 25, and 4 (light Information recording media 1b, 1e and 1f) are also possible.

  The transparent resin layer 11 needs to be transparent at the wavelength of the reproducing beam 30 and not to prevent the incident of the reproducing beam 30. Thereby, the optical information recording medium 1a of the type in which the reproduction beam 30 enters from the transparent resin layer 11 side can be configured. The material constituting the transparent resin layer 11 is not particularly limited. For example, polycarbonate, amorphous polyolefin, thermoplastic polyimide, PET (polyethylene terephthalate), PEN (polyether nitrile), PES (polyether sulfone) ) And other thermoplastic transparent resins (plastics); thermosetting transparent resins such as thermosetting polyimides and ultraviolet curable acrylic resins, and combinations thereof. The transparent resin layer 11 usually has a thickness of about 1 to 100 μm. Moreover, the transparent resin layer 11 may have a thickness of about 0.1 to 1.2 mm, and in that case, an appropriate strength can be imparted to the optical information recording medium 1a. Instead of the transparent resin layer 11, other transparent materials such as glass or a layer made of a combination of glass and transparent resin may be used. In that case, the thickness is suitably about 0.1 to 1.2 mm.

  The substrate 12 must be capable of imparting appropriate strength to the optical information recording medium 1a. The optical characteristics of the material constituting the substrate 12 are not particularly limited, and may be transparent or opaque. Examples of the material constituting the substrate 12 include glass; thermoplastic transparent resins such as polycarbonate, amorphous polyolefin, thermoplastic polyimide, PET, PEN, and PES; thermosetting resins such as thermosetting polyimide and ultraviolet curable acrylic resin. Transparent resins; metals, etc., and combinations thereof. The thickness of the board | substrate 12 is not specifically limited, For example, about 0.3-1.2 mm is suitable. The pit pitch is about 0.3 to 1.6 μm, and the pit depth is about 30 to 200 nm. Further, the guide groove has a pitch of about 0.3 to 1.6 μm and a depth of about 30 to 200 nm.

  On the inner surface of the substrate 12 (surface on the temperature-sensitive reflective layer 13 side), concave and convex pits and guide grooves corresponding to the recorded information are formed. Both pits and grooves may be formed, or only one of them may be formed.

  The temperature-sensitive reflection layer 13 has a function of changing the transmittance and / or the reflectance at the wavelength of the reproduction beam 30 in accordance with the temperature change caused by the irradiation of the reproduction beam 30. Thereby, it is possible to selectively perform reproduction in an area having a size smaller than the spot size of the reproduction beam 30. The temperature sensitive reflective layer 13 is formed of a temperature sensitive layer 21, a light absorbing layer 22, a reflective layer 23 and / or a heat insulating layer 24. For example, in the basic optical information recording medium 1a shown in FIG. The temperature sensitive layer 21, the light absorbing layer 22, and the reflective layer 23 are laminated in this order from the side on which the (reproducing beam 30) is incident, that is, from the transparent resin layer 11 side. That is, the temperature sensitive reflective layer 13 is configured by laminating the reflective layer 23, the light absorbing layer 22, and the temperature sensitive layer 23 in this order on the substrate 12.

The temperature sensitive layer 21 has a function of changing the transmittance at the wavelength of the reproduction beam 30 in accordance with the temperature rise of the light absorption layer 22 by irradiation of the reproduction beam 30. The temperature-sensitive layer 21 is a translucent material whose transmittance changes reversibly with changes in temperature, and includes a material whose transmittance at the reproduction light beam wavelength changes as the temperature rises. As the material, a material whose transmittance of the temperature sensitive layer 21 changes greatly in a specific wavelength region when the temperature rises, specifically, when the temperature rises from 20 ° C. to 180 ° C., the temperature sensitive layer 21 A material whose light transmittance changes within a range of ± 80% is suitable. As the material, a thermochromic substance can be used. A thermochromic substance is a substance that undergoes a chemical structural change and absorbs heat by absorbing heat. Specific examples of thermochromic substances whose transmittance decreases with changes in temperature include inorganic thermochromic substances such as metal oxides; lactones and fluoranes added with alkalis, leuco dyes and other organic acids. Organic thermochromic substances such as those added may be mentioned. Among these, metal oxides whose transmittance at the absorption edge wavelength changes by changing the forbidden band according to temperature are preferable. This is because such metal oxides are not easily changed in composition and shape even when chemical structural changes due to temperature changes are repeated, and are excellent in durability. Specific examples of the metal oxide include ZnO, SnO ₂ , CeO ₂ , NiO ₂ , In ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , VO ₂ , SrTiO _{3, and the} like. Of these, ZnO (zinc oxide) is particularly preferable. The film thickness of the temperature sensitive layer 21 can be adjusted depending on the material to be used. For example, about 5 to 800 nm is suitable, but the layer thickness of the temperature sensitive layer 21 is preferably 100 nm or more. Therefore, the temperature sensitive layer 21 is most preferably a ZnO (zinc oxide) film having a thickness of 100 nm or more.

  The light absorbing layer 22 supplementarily changes the temperature of the temperature sensitive layer 21 by irradiation of the reproduction beam 30. That is, the light absorption layer 22 has a function of changing the light absorption amount (reflectance and / or transmittance) of the temperature sensitive layer 21. The light absorption layer 22 is preferably made of a material that absorbs the reproduction laser beam (reproduction beam 30) and converts it into heat. Specific examples include Si films, Ge films, phase change films such as AgInSbTe films and GeSbTe films, magneto-optical films such as TbFeCo films, DyFeCo films, and GdFeCo films, and alloy films thereof. Most preferably it is. The film thickness of the light absorption layer 22 can be adjusted depending on the material to be used. For example, about 5 to 300 nm is appropriate, but the layer thickness of the light absorption layer 22 is preferably 10 nm or more. Therefore, the light absorption layer 22 is most preferably a Si (silicon) film having a thickness of 10 nm or more.

  In addition, as shown in FIG. 1, it is preferable that the temperature sensitive layer 21 and the light absorption layer 22 are adjacently comprised. Thereby, for example, the light absorption layer 22 absorbs the reproduction beam 30 and converts it into heat, so that the temperature of the temperature sensitive layer 21 can be increased more efficiently. However, the temperature sensitive layer 21 and the light absorption layer 22 do not necessarily have to be adjacent to each other as long as they are close to a range in which the temperature of the temperature sensitive layer 21 can be changed. For example, another layer (for example, a layer (transparent dielectric layer) for providing a multiple reflection effect by light interference) may be formed between the temperature sensitive layer 21 and the light absorption layer 22.

  The reflective layer 23 reflects the light transmitted through the temperature sensitive layer 21 and the light absorbing layer 22. The reflective layer 23 is preferably formed of a metal film having a high reflectance. Specific examples of the metal film having a high reflectance include an Al film, an Au film, an Ag film, and an alloy film thereof. The layer thickness of the reflective layer 23 is not particularly limited, and can be adjusted to a layer thickness that can realize a desired reflectance, and for example, about 20 to 100 nm can be mentioned.

  Furthermore, the temperature-sensitive reflective layer 13 has not only the basic optical information recording medium 1a shown in FIG. 1 but also the optical information recording media 1b to 1f shown in FIG. 2 and FIGS. You can also. That is, in the present invention, the temperature-sensitive reflective layer 13 may have the reflective layer 23 and / or the heat insulating layer 24 in addition to the temperature-sensitive layer 21 and the light absorbing layer 22.

  More specifically, the temperature-sensitive reflective layer 13 has a heat insulating layer 24 instead of the reflective layer 23 of the optical information recording medium 1a as in the optical information recording media 1c and 1e (see FIGS. 22 and 24). There may be. In this case, the efficiency of reflecting the light transmitted through the temperature sensitive layer 21 and the light absorption layer 22 is inferior to the case where the reflective layer 23 is provided. However, since the heat insulating layer 24 has heat insulating properties, the temperature of the temperature sensitive layer 21 can be increased more efficiently by the heat generated in the light absorbing layer 22 than when the heat insulating layer 24 is not provided. Can do.

  Further, the temperature-sensitive reflective layer 13 includes a heat insulating layer 24 between the light absorbing layer 22 and the reflective layer 23 of the optical information recording medium 1a as in the optical information recording media 1d and 1f (see FIGS. 23 and 25). The structure which has may be sufficient. In this case, in addition to the above-described advantages of the optical information recording media 1c and 1e (that is, the temperature of the temperature sensitive layer 21 can be increased efficiently), the light transmitted through the heat insulating layer 24 is efficiently transmitted. It can be reflected by the reflective layer 23.

  In addition, the heat insulation layer 24 will not be specifically limited if it is a substance with small heat conductivity. However, the heat insulating layer 24 is preferably transparent in the case of an optical information recording medium having the reflective layer 23, and is preferably a substance having a high reflectance in the case of an optical information recording medium not having the reflective layer 23. . Examples of the heat insulating layer 24 include a SiN film and an AlN film, and a SiN film is preferable. The film thickness of the heat insulation layer 24 is not particularly limited, and can be adjusted to a thickness that can achieve a desired transmittance or reflectance. For example, the film thickness of the heat insulation layer 24 can be about 20-100 nm.

  In the optical information recording media 1a to 1f, the incident light is reflected not only by the reflective layer 23 or the heat insulating layer 24 but also by each of the temperature sensitive layer 21 and the light absorbing layer 22.

  With such a configuration, a writable recording film such as a so-called CD (Compact Disc), CD-ROM (Compact Disc Read Only Memory), DVD (Digital Versatile Disc), DVD-ROM (Digital Versatile Disc Read Only Memory), etc. A reproduction-only optical information recording medium 1 that does not have can be realized.

  Next, an example of a method for reproducing the optical information recording medium 1 will be described.

  The optical information recording medium 1a uses a laser light source (not shown) and an optical system such as a condenser lens 31 to reproduce the reproduction beam 30 from the transparent resin layer 11 side to the inner surface of the substrate 12 (at least one of pits and grooves). Can be reproduced by detecting light reflected on the surface with an optical head (not shown).

  At this time, irradiation of the reproduction beam 30 to the optical information recording medium 1 a is performed so that a high temperature portion and a low temperature portion are generated in the light beam spot in the temperature sensitive layer 21. For example, when a reproduction beam 30 is incident on the optical information recording medium 1 dedicated to reproduction from the transparent resin layer 11 side and the surface of the optical information recording medium 1 is scanned in a predetermined direction with the reproduction beam 30, the surface of the temperature sensitive layer 21. In the reproduction beam spot 33, a temperature gradient is generated in the traveling direction of the reproduction beam spot 33 as shown in FIG. Therefore, a high temperature portion 33 a and a low temperature portion 33 b are generated in the reproduction beam spot 33 on the surface of the temperature sensitive layer 21. For example, the temperature of the high temperature portion 33a is 60 ° C. or higher and lower than 180 ° C., and the temperature of the low temperature portion 33b is 20 ° C. or higher and lower than 60 ° C.

  As described above, the transmittance of the temperature sensitive layer 21 changes with temperature change. For example, when the transmittance of the temperature sensitive layer 21 decreases as the temperature increases, the transmittance of the temperature sensitive layer 21 at the wavelength of the reproduction beam 30 is reduced in the high temperature portion 33a where the temperature is increased by the incidence of the reproduction beam 30. (Low transmittance state). As a result, most of the light incident on the optical information recording medium 1a is blocked by the temperature sensitive layer 21, so that the amount of light transmitted through the temperature sensitive layer 21 is reduced. As a result, the amount of light incident on the reflective layer 23 on the back side (substrate 12 side) of the temperature sensitive layer 21 is also reduced. Accordingly, since the amount of reflected light reflected by the reflective layer 23 is suppressed, the temperature sensitive reflective layer 13 as a whole is in a low reflectance state.

  On the other hand, in the low temperature part 33 b where the temperature is lower than that of the high temperature part 33 a, the transmittance of the temperature sensitive layer 21 at the wavelength of the reproduction beam 30 is not changed by the irradiation of the reproduction beam 30. Therefore, the transmittance of the low temperature portion 33b is relatively higher than the transmittance of the high temperature portion 33a. As a result, the amount of light incident on the reflective layer 23 on the back side (substrate 12 side) of the temperature sensitive layer 21 increases. Therefore, the amount of reflected light reflected by the reflective layer 22 also increases, and the temperature sensitive reflective layer 13 is in a highly reflective state.

  In addition, the optical information recording medium 1 a has a light absorption layer 22 that assists the temperature change of the temperature sensitive layer 21. For this reason, when the reproduction beam 30 is irradiated to the light absorption layer 22, the light absorption layer 22 absorbs the reproduction beam 30 and converts it into heat. Since the light absorption layer 22 and the temperature sensitive layer 21 are close (preferably adjacent), the heat generated in the high temperature portion 33 a of the light absorption layer 22 moves to the temperature sensitive layer 21. As a result, the temperature of the high temperature portion 33a of the temperature sensitive layer 21 becomes higher. That is, since the temperature difference between the low temperature portion 33b and the high temperature portion 33a is increased, the transmittance of the high temperature portion 33a of the temperature sensitive layer 21 is further reduced. Thereby, light can be blocked | interrupted in the high temperature part 33a much more than the case where it does not have the light absorption layer 22. FIG.

  In addition to this, in the case of the optical information recording media 1c to 1f having the heat insulating layer 24 as shown in FIGS. 21 to 25, the heat generated in the light absorbing layer 22 is more efficiently applied to the temperature sensitive layer 21. Therefore, the light can be further blocked by the high temperature portion 33a.

  That is, specifically, the temperature sensitive reflection layer 13 can be in a low reflectance state at, for example, 60 ° C. or more and less than 180 ° C., and in a high reflectance state at 20 ° C. or more and less than 60 ° C. Furthermore, by having the light absorption layer 22 and the heat insulation layer 24, it can be set to a high reflectance state or a low reflectance state more efficiently.

  As a result, the temperature sensitive layer 21 is difficult to transmit the reproduction beam 30 in the latter half portion of the reproduction beam spot 33 which is the high temperature portion 33a. Accordingly, light is substantially blocked by the high temperature portion 33a of the temperature sensitive layer 21, and information is reproduced based on the light transmitted through the low temperature portion 33b of the temperature sensitive layer 21. That is, in a state where the substrate 12 is masked by the high temperature portion 33a, the reflected light on the surface of the substrate 12 that has passed through the low temperature portion 33b where the temperature has not risen is detected by the optical head, and reproduction is performed. Thereby, the size of the reproduction region on the surface of the substrate 12 (recording information surface) on which the pits and / or grooves are formed can be made smaller than the reproduction beam spot 33 on the temperature sensitive reflection layer 13. As a result, the size of the playback area can be further reduced, and the playback resolution can be improved. Therefore, the information corresponding to the minute pits and / or grooves carved on the surface (recording information surface) of the substrate 12, particularly the pits and / or grooves below the diffraction limit of the reproduction light beam can be reliably obtained with a larger reproduction signal intensity. Can be played. As described above, in the optical information recording medium of the present embodiment, the temperature sensitive layer 21, the light absorbing layer 22, the reflective layer 23, and / or the heat insulating layer 24 are used on the surface of the substrate 12 (recording information surface). A minute recording mark below the diffraction limit of a reproducing light beam engraved as pits and / or grooves can be reproduced.

  In addition, the reproducing method of the optical information recording medium in the case where the transmittance of the temperature sensitive layer 21 decreases with increasing temperature has been described with reference to FIG. On the other hand, in the reproducing method of the optical information recording medium when the temperature sensitive layer 21 increases in transmittance as the temperature rises, the high temperature portion 34a of the reproducing beam spot 34 has a high reflectance as shown in FIG. This is almost the same except that the low temperature portion 34b is in a low reflectance state. That is, in the temperature sensitive layer 21, the reproduction beam 30 is hardly transmitted through the first half portion of the reproduction beam spot 34 that is the low temperature portion 33 b. Therefore, light is substantially blocked by the low temperature portion 34b of the temperature sensitive layer 21, and information is reproduced based on the light transmitted through the high temperature portion 34a of the temperature sensitive layer 21. That is, in a state where the substrate 12 is masked by the low temperature portion 34b, the reflected light on the surface of the substrate 12 that has passed through the high temperature portion 34a whose temperature has risen is detected by the optical head, and reproduction is performed.

  Furthermore, as described above, the mask layer that increases the transmittance of the high-temperature portion used in Patent Document 1 is a thermochromic material that exhibits a mask effect by melting when heated to a certain temperature or higher. Since it is formed of a substance such as a phase change material, there is a problem that the mask effect is lowered when repeated recording and reproduction are performed.

  On the other hand, in this embodiment, the temperature sensitive layer 21 that reduces or increases the transmittance of the high temperature portion 33a or 34a is used. Further, the temperature of the high temperature portion 33 a or 34 a of the temperature sensitive layer 21 is further increased by the light absorption layer 22. Furthermore, the temperature of the high temperature portion 33a or 34a of the temperature sensitive layer 21 is efficiently increased by the heat insulating layer 24. Since the temperature sensitive layer 21 can be formed of a material such as a metal oxide that does not melt due to a temperature rise during recording or reproduction, the mask effect does not deteriorate even when repeated recording and reproduction are performed. Therefore, the optical information recording medium 1a of the present embodiment has an advantage that it is excellent in durability.

  In the optical information recording medium 1 of the present embodiment, the light absorption layer 22 and the reflection layer 23 are formed on the back surface of the surface of the temperature sensitive layer 21 where the light beam is irradiated. The absorption layer 22 and the reflection layer 23 constitute a temperature-sensitive reflection layer 13 in which the reflectance of the irradiated light beam decreases as the temperature increases due to the light beam irradiation. The above configuration is a super-resolution reproduction method that uses a mask layer provided to change the transmittance on the light incident side, that is, a super-resolution reproduction method that uses a substance that melts due to a temperature rise during recording or reproduction. (Patent Documents 1 and 2 etc.) use a reflection type super-resolution reproduction system whose principle is fundamentally different.

  In the temperature sensitive layer 21, the transmittance reduction region accompanying absorption on the short wavelength side at normal temperature includes the wavelength of the reproduction light beam, and the transmittance reduction region accompanying absorption on the short wavelength side is long wavelength as the temperature rises. It is preferable that the spectral transmittance at the wavelength of the reproduction light beam is lowered by shifting to the short wavelength side or the short wavelength side. The temperature-sensitive layer 21 has an absorption wavelength on the short wavelength side at room temperature (lower limit of the absorption band existing in the ultraviolet / visible region) shorter than the wavelength of the reproduction beam 30, and absorbs on the short wavelength side as the temperature rises. It is preferable that the end wavelength shifts to the long wavelength side or the short wavelength side, and the spectral transmittance at the wavelength of the reproduction beam 30 decreases. For example, when the wavelength of the reproduction beam 30 is within the range of 380 nm to 415 nm (for example, 408 nm), the temperature sensitive layer 21 has an absorption edge wavelength on the short wavelength side near room temperature of 375 nm. A ZnO film is preferred.

  In the spectral transmittance characteristics of the ZnO film, as shown in FIG. 15, the absorption edge wavelength on the short wavelength side shifts to the long wavelength side as the temperature rises. Thereby, the ZnO film of the high-temperature portion 33a that has been heated by the incidence of light has a low spectral transmittance at a wavelength of the reproduction beam 30 and a low transmittance state. Note that the ZnO film in the low temperature portion 33b having a relatively low temperature remains high in light transmittance. Further, when the temperature of the portion of the ZnO film that has been raised is lowered, the absorption edge wavelength on the long wavelength side of the spectral transmittance characteristic returns to the short wavelength side, and the spectral transmittance increases. Thereby, the modulation degree (change in spectral transmittance at the wavelength of the reproduction beam 30 between the high temperature portion 33a and the low temperature portion 33b) can be increased. In addition to this, the light absorption layer 22 raises the temperature of the high temperature part 33a. Therefore, the reproduction beam 30 is less likely to be transmitted through the high temperature portion 33a, and a high reproduction signal intensity can be obtained more reliably.

  Moreover, it is preferable that the temperature-sensitive layer 21 is controlled in temperature change of transmittance characteristics by using an optical interference effect between reflected light on one surface and reflected light on the other surface. The spectral reflectance characteristic of the temperature sensitive layer 21 is such that a minimum value due to the optical interference effect between the reflected light on one surface and the reflected light on the other surface is near the wavelength of the light beam (preferably within ± 20 nm, and further Preferably it is within ± 10 nm. When the thickness of the temperature sensitive layer 21 is increased to 200 nm or more, optical interference occurs between the reflected light on one surface and the reflected light on the other surface. For example, the spectral reflectance characteristics of a film made of a zinc oxide film (400 nm) and an aluminum film that do not have the light absorption layer 22 are, as shown in FIG. In FIG. 17, it has 400 nm). This makes it possible to increase the slope of the reflectance near the absorption edge, and as a result, the degree of modulation (change in spectral transmittance at the wavelength of the reproduction beam 30 between the high temperature portion 33a and the low temperature portion 33b). ) Can be increased. Therefore, the reproduction beam 30 is less likely to be transmitted through the high temperature portion 33a, and a high reproduction signal intensity can be obtained more reliably. If the film thickness of the film made of the aluminum film is less than 40 nm, optical interference does not occur, and the spectral reflectance characteristic does not have a minimum value due to the optical interference effect, for example, as shown in FIG. .

  FIG. 18 is a graph showing spectral reflectance characteristics in the configuration using the light absorption layer 22 shown in FIG. FIG. 9 shows an absorber shift and optical interference effect in an optical information recording medium having a ZnO film (210 nm) as the temperature sensitive layer 21, an Si film (50 nm) as the light absorption layer 22, and an Al film (30 nm) as the reflection layer 23. Is shown. According to this, it is understood that the reflectance is lower than that without the light absorption layer 22 (see FIGS. 16 and 17), that is, the light absorption amount is increased. The optical information recording medium shown in FIG. 18 can have a high-temperature mask structure in which the reflectance is high at the low temperature portion and the reflectance is reduced at the high temperature portion, as in the case of FIG. In the optical information recording medium using the light absorbing layer 22, the temperature of the temperature sensitive layer 21 is more likely to rise. Therefore, the reproduction power sensitivity of the optical information recording medium can be increased. That is, when the light beam having the same irradiation amount is irradiated, the temperature rise of the temperature sensitive layer 21 becomes larger than when the light absorbing layer 22 is not provided, and thus the reproduction sensitivity of the optical information recording medium is further increased. Can do.

  Further, as shown in FIG. 26, the temperature of the temperature sensitive layer 21 can be increased more efficiently than when the heat insulating layer 24 is used (● in the figure) and when the heat insulating layer 24 is not used (▲ in the figure). And the reproduction sensitivity can be increased. That is, by having the heat insulating layer 24, super-resolution reproduction can be performed with a smaller reproduction power.

  FIG. 20 is a graph showing the recording mark dependency data of the CN ratio, which is one of the reproduction signal characteristics, for the optical information recording medium 1a having the light absorption layer 22 described above. According to this, when the film thickness of the temperature sensitive layer 21 is increased (210 nm → 230 nm), the spectral reflectance characteristic has a low temperature mask structure in which the reflectance increases as the temperature rises as shown in FIG. In the case of such a film configuration, the temperature distribution in the reproduction beam spot 34 is as shown in FIG. 14, and contrary to FIG. 13, the low temperature portion 34b has a low reflectance and the high temperature portion 34a has a high reflectance. . In this case, it is possible to reproduce information accurately and reliably by reproducing the light transmitted through the high temperature part 34a.

  FIG. 15 shows spectral transmittance characteristics in the vicinity of the absorption edge of the temperature sensitive layer 21 made of a ZnO film having a thickness of 400 nm at low temperature (30 ° C.) and high temperature (200 ° C.). FIG. 16 shows spectral reflectance characteristics in the vicinity of the absorption edge of the temperature-sensitive reflective layer 13 composed of a ZnO film having a thickness of 100 nm and an Al film having a thickness of 50 nm at a low temperature (30 ° C.) and a high temperature (200 ° C.). FIG. 17 shows spectral reflectance characteristics in the vicinity of the absorption edge of the temperature-sensitive reflective layer 13 composed of a ZnO film having a thickness of 400 nm and an Al film having a thickness of 50 nm at a low temperature (30 ° C.) and a high temperature (200 ° C.). FIG. 18 shows the temperature-sensitive reflective layer 13 composed of a 210 nm-thickness ZnO film, a 50-nm-thickness Si film, and a 30-nm-thick Al film at low temperature (30 ° C.) and high temperature (200 ° C.). Spectral reflectance characteristics are shown. FIG. 19 shows the absorption near the absorption edge of the temperature-sensitive reflective layer 13 composed of a ZnO film having a thickness of 230 nm, a Si film having a thickness of 50 nm, and an Al film having a thickness of 30 nm at a low temperature (30 ° C.) and a high temperature (200 ° C.). Spectral reflectance characteristics are shown.

The absorption edge wavelength change of these temperature sensitive layers 21 is due to the temperature change of the forbidden band width of the metal oxide semiconductor. Besides ZnO, ZnS, SnO ₂ , CeO ₂ , NiO ₂ , In ₂ O ₃ , Metal oxides such as TiO ₂ , Ta ₂ O ₅ , VO ₂ , and SrTiO ₃ are also effective.

  FIG. 26 shows a temperature sensitive reflection layer 13 composed of a 150 nm thick ZnO film, a 50 nm thick Si film, and a 30 nm thick Al film, a 150 nm thick ZnO film, and a 50 nm thick film. It is a graph which shows the CNR-reproduction power dependence of the temperature sensitive reflection layer 13 which consists of Si film and a 20-nm-thick SiN film. Thus, it can be seen that by having SiN, super-resolution reproduction with a smaller reproduction power can be performed.

  Hereinafter, an example of the optical information recording medium 1 of the present embodiment will be described.

  In an example of the optical information recording medium of the present embodiment, the transparent resin layer 11 has a thickness of about 0.1 mm. Moreover, in an example of the optical information recording medium of the present embodiment, pits having a concavo-convex pattern corresponding to information are formed on the inner surface of the substrate 12 (the surface on the temperature-sensitive reflective layer 13 side). In this example, the temperature sensitive layer 21 is a ZnO film having a thickness of about 200 nm. In this example, the light absorption layer 22 is a Si film having a thickness of about 50 nm. In this example, the reflective layer 23 is an Al film having a thickness of about 30 nm.

  The optical information recording medium of the present embodiment can be manufactured, for example, by the following method.

  As shown in FIG. 1, first, a metal film as a reflection layer 23 and a light absorption layer 22 are formed on a substrate 12 having a surface (information recording surface) on which pits and / or grooves corresponding to recording information are formed. The Si film and the temperature sensitive layer 21 are sequentially formed by a magnetron sputtering method to form the temperature sensitive reflective layer 13. After the temperature-sensitive layer 21 is formed, in order to protect the information recording surface and the temperature-sensitive reflective layer 13 from the external environment, an ultraviolet curable acrylic resin or the like is spin-coated on the temperature-sensitive reflective layer 13 and cured by ultraviolet irradiation. Thus, the transparent resin layer 11 is formed. Further, as shown in FIGS. 2 and 4, the temperature sensitive layer 21 can be formed of an oxide and a stable substance, and thus a configuration without the transparent resin layer 11 (optical information recording medium 1b) is possible.

  Although the case where the recording / reproducing beam is incident on the optical information recording medium 1 from the transparent resin layer 11 side has been described here, the optical information recording medium of the present invention is the same as the optical information recording medium 1. It may be an optical information recording medium having a layer structure (however, the positions of the temperature sensitive layer 21 and the reflective layer 23 in the temperature sensitive reflective layer 13 are reversed) and the reproduction light beam is incident from the substrate 12 side. . In this configuration, it is preferable that a protective layer is formed on the opposite side of the temperature-sensitive reflective layer 13 from the substrate 12.

  In this configuration, the substrate 12 is preferably one that does not interfere with the incidence of the reproduction light beam and can impart an appropriate strength to the optical information recording medium, such as glass; polycarbonate, amorphous polyolefin, thermoplastic polyimide, Examples thereof include thermoplastic transparent resins such as PEN and PES; thermosetting transparent resins such as thermosetting polyimide and ultraviolet curable acrylic resin, and combinations thereof. As the thickness of the substrate 12, it is usually appropriate to have a thickness of about 0.3 to 1.2 mm.

  In this configuration, the protective layer may be made of any material that can protect the temperature-sensitive reflective layer 13. Specifically, the same material as the substrate 12 is used. Note that the protective layer may be transparent or opaque. The protective layer usually has a thickness of about 1 to 100 μm.

  Further, in the optical information recording medium of the present invention, it is preferable that pits and / or grooves are formed only on one side of the substrate 12 as in the optical information recording medium 1. Both or one of them may be formed.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIGS. 5 to 12 and FIGS. 27 to 34. FIG. For convenience of explanation, members having the same functions as those shown in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  Optical information recording media according to the present embodiment are optical information recording media 2a, 2e, and 2g for recording / reproducing (write-once type or rewritable type), as shown in FIGS. 5, 9, 27, and 29. The transparent resin layer 11, the recording layer 14, the temperature-sensitive reflective layer 13, and the substrate 12 are formed in this order from the side on which the recording / reproducing beam 32, which is a recording or reproducing light beam, enters. The recording / reproducing beam 32 is a light beam that outputs recording power during recording and outputs reproducing power during reproduction.

  The temperature-sensitive reflection layer 13 is the same as that of the first embodiment, and the temperature-sensitive layer 21, the light absorption layer 22, the reflection layer 23 and / or the heat insulation from the side on which the recording / reproducing beam 32 is incident (the transparent resin layer 11 side). The layer 24 is laminated in this order. 6, 10, 31. Since the temperature sensitive layer 21 can be formed of an oxide and a stable substance as shown in FIGS. 3 and 33, a configuration without the transparent resin layer 11 (optical information recording media 2b, 2i, 2k) is also possible.

  Further, as shown in FIGS. 7, 11, 28, and 30, optical recording media 2c, 2f, and 2h for recording / reproduction (write-once type or rewritable type) are recording / reproduction light beams. A configuration in which the transparent resin layer 11, the temperature sensitive reflection layer 13, the recording layer 14, and the substrate 12 are formed in this order from the side on which the recording / reproducing beam 32 is incident is also possible. The temperature sensitive reflection layer 13 is formed by laminating the temperature sensitive layer 21, the light absorption layer 22, and the reflection film 23 in this order from the side on which the recording / reproducing beam 32 is incident (the transparent resin layer 11 side). As shown in FIGS. 8, 12, 32, and 34, the temperature sensitive layer 21 can be formed of an oxide and a stable substance, so that even in a configuration without the transparent resin layer 11 (optical information recording media 2d, 2j, and 2l). Is possible.

The recording layer 14 can be formed of a recording material usually used in the field. For example, when the optical information recording medium 2 is a write-once medium, an organic dye material such as cyanine or phthalocyanine can be used. When the optical information recording medium 2 is a rewritable (recording / reproducing / erasing type) medium, a magneto-optical recording material such as TbFeCo or a phase change recording material such as AgInSbTe, GeTeSb, or AgInSb can be used. In the case of using a magneto-optical recording material such as TbFeCo, the recording layer 14 is made of, for example, a dielectric layer made of a dielectric material such as SiN (silicon nitride), a recording layer made of a magneto-optical recording material, and protection of SiN or the like. A laminated structure including three protective layers made of a material is preferable. When a phase change recording material such as AgInSbTe, GeTeSb, or AgInSb is used, the recording layer 14 is made of, for example, a dielectric layer such as a ZnS / SiO ₂ film, or a phase change recording material such as AgInSbTe, GeTeSb, or AgInSb. A laminated structure including a recording layer and a protective layer such as a ZnS / SiO ₂ film is preferable. The layer thickness of the recording layer 14 is not particularly limited, and for example, about 5 to 500 nm is appropriate.

  As in the first embodiment, the substrate 12 may be any material that can impart an appropriate strength to the optical information recording medium 1, and may be transparent or opaque. Examples of the material constituting the substrate 12 include the materials constituting the substrate 12 described above. The thickness of the board | substrate 12 is not specifically limited, For example, about 0.3-1.2 mm is suitable. In this embodiment, a flat substrate may be used instead of the substrate 12 on which pits and grooves are formed.

  The transparent resin layer 11 and the temperature sensitive reflection layer 13 are the same as those in the first embodiment except that the recording layer 14 is interposed therebetween.

  With such a configuration, so-called CD-R (Compact Disc Recordable), CD-RW (Compact Disc ReWritable), DVD-R (Digital Vesatile Disc Recordable), DVD-RW (Digital Vesatile Disc ReWritable), DVD-RAM (Digital An optical information recording medium having a writable recording layer such as Vesatile Disc Random Access Memory (MO) or MO (Magneto-Optical disc) can be realized.

  The optical information recording media 2a to 2l can be reproduced by the same reproducing method as the optical information recording medium 1 of the first embodiment. That is, the recording / reproducing beam 32 is made incident on the recording layer 14 from the transparent resin layer 11 side or the temperature sensitive layer 21 side using a laser light source (not shown) and an optical system such as a condenser lens 31. At this time, the light beam is irradiated so that a high-temperature portion and a low-temperature portion are generated in the light beam spot in the temperature-sensitive layer 21, and the transmittance of the temperature-sensitive layer 21 at the high-temperature portion is changed. Information reflected on the recording layer 14 is detected by an optical head (not shown) to reproduce information based on the light transmitted through the low temperature portion of the temperature sensitive layer 21.

  In the optical information recording media 2a, 2b, 2e, 2g, 2i, and 2k, the temperature-sensitive reflection layer 13 is formed on the back surface of the recording layer 14 (the back surface of the surface irradiated with the recording / reproducing beam 32) as viewed from the incident light. Therefore, at the time of reproduction, when the recording / reproducing beam 32 is guided to the guide groove of the transparent substrate, the recording / reproducing beam 32 enters the temperature-sensitive reflective layer 13 through the recording layer 14. By the incidence of the recording / reproducing beam 32, as described above, the temperature of the temperature sensitive reflection layer 13 rises, and the second half of the reproducing beam spot becomes high temperature, and the other parts become low temperature. Further, the high temperature portion becomes higher temperature by the light absorption layer 22. And since the temperature sensitive reflection layer 13 has the property that a reflectance changes according to temperature rise, it will be in the state of low reflectance in a high temperature part, and will be in the state of high reflectance in a low temperature part. As a result, the information recorded on the recording layer 14 can be reproduced with a small opening (low temperature portion) below the optical spatial resolution (diffraction limit of the reproduction light beam). It becomes possible to reproduce with high quality. As described above, in the optical information recording medium of the present embodiment, the recording layer 14 is reproduced using the temperature-sensitive layer 21 and the light absorption layer 22 so as to reproduce a minute recording mark below the diffraction limit of the reproducing light beam recorded on the recording layer 14. It is possible.

  The optical information recording media 2a, 2b, 2e, 2g, 2i, and 2k according to the present embodiment are provided with the temperature sensitive layer 21 on the back side of the recording layer 14 when viewed from the incident light. There are the following advantages over the configurations of Patent Documents 1 and 2 in which the mask layer is provided on the light incident side of the recording layer. That is, by providing the temperature sensitive layer 21 on the back surface of the recording layer 14, it is possible to easily increase the temperature of the temperature sensitive layer 21 using optical interference. As a result, it is possible to reproduce with lower laser power and to realize an optical information recording medium with high reproduction sensitivity.

  Furthermore, since the optical information recording media 2a to 2l according to the present embodiment use the temperature sensitive layer 21 that reduces or increases the transmittance of the high temperature portion 33a, as in the first embodiment, the recording and reproduction are performed. The temperature sensitive layer 21 can be formed of a material such as a metal oxide that does not melt due to a temperature rise. Therefore, even if repetitive recording and reproduction are performed, there is an advantage that the mask effect is not lowered and the durability is excellent.

  According to the configuration of the optical information recording media 2a, 2b, 2e, 2g, 2i, and 2k, the temperature sensitive layer 21 is provided on the back side of the surface of the recording layer 14 on which the recording / reproducing beam 32 is irradiated. There are the following advantages over the configurations of Patent Documents 1 and 2 in which the mask layer is provided on the light incident side of the recording layer 14. That is, in the optical information recording media of Patent Documents 1 and 2 having a recording film on the substrate, since the mask layer is formed on the light incident side of the recording film, at least one of the total amount of light reaching the recording layer. Part is absorbed by the mask layer. Therefore, high signal quality cannot be obtained due to a decrease in recording sensitivity or an increase in reproduction noise. On the other hand, by providing the temperature sensitive layer 21 on the back surface of the recording layer 14, the temperature of the temperature sensitive layer 21 can be easily increased by using optical interference. As a result, it is possible to reproduce with lower laser power and to realize an optical information recording medium with high reproduction sensitivity.

  The recording method is not particularly limited, but the following method is preferable. That is, at the time of recording, when the recording / reproducing beam 32 is irradiated to the optical information recording media 2c, 2d, 2f, 2h, 2j, and 2l, a high-temperature portion and a low-temperature portion are generated in the temperature-sensitive reflective layer 13, for example, When the transmittance is lowered in the high temperature portion, the minute region of the recording layer 14 is selectively heated by the light transmitted through the low temperature portion. As a result, information can be recorded in a minute area of the recording layer 14, so that high-density recording can be realized. Further, when the recording / reproducing beam 32 is irradiated to the optical information recording media 2a, 2b, 2e, 2g, 2i, and 2k, a high temperature portion and a low temperature portion are generated in the recording layer 14, and a minute region of the recording layer 14 is selected. Heat up. As a result, information can be recorded in a minute area of the recording layer 14, so that high-density recording can be realized.

  In each of the above-described embodiments, the transmittance of the temperature sensitive layer 21 at the reproduction light beam wavelength is reduced as the temperature rises. However, for example, even in the temperature sensitive layer 21 having the transmittance characteristics shown in FIGS. 15 to 17, the transmittance may not necessarily decrease due to the temperature rise depending on the setting of the reproduction light beam wavelength. That is, in the case of the temperature sensitive layer 21 having the transmittance characteristics shown in FIGS. 15 to 17, the transmittance decreases at a high temperature at a wavelength of 405 nm, but when the reproduction light beam wavelength is set longer than that, the transmittance is reduced. May rise at high temperatures. Therefore, this is also effective when the reproduction light beam wavelength is set so that the transmittance increases at a high temperature. In other words, the temperature sensitive layer 21 may be one whose transmittance at the reproduction light beam wavelength increases as the temperature increases.

  In the optical information recording media 1 and 2 in which the transmittance of the temperature sensitive layer 21 at the reproduction light beam wavelength increases as the temperature rises, a high temperature portion and a low temperature portion are generated in the light beam spot in the temperature sensitive layer 21. By irradiating the light beam, the transmittance at the high temperature portion of the temperature sensitive layer 21 is increased, and the reflected light from the recording layer 14 is detected by an optical head (not shown), so that the high temperature portion of the temperature sensitive layer 21 is detected. Information can be reproduced by a method of reproducing information based on the transmitted light.

  Further, FIGS. 18 and 19 show spectral reflection spectra when the light absorption layer 22 is used on the back side (substrate 12 side) of the temperature sensitive layer 21. By using this structure, the temperature reached by the temperature sensitive layer 21 can be increased with a lower laser power, so that it is possible to realize a super-resolution reproduction medium with high medium reproduction sensitivity. Even in this case, it is possible to design either a high-temperature mask type (FIG. 18) in which the reflectivity decreases with an increase in temperature or a low-temperature mask type (FIG. 19) in which the reflectivity increases with an increase in temperature.

  The reproduction resolution characteristics (● in the figure) of the optical information recording medium including such a light absorption layer 22 (including the temperature sensitive reflection layer 13) can be obtained by using only the temperature sensitive layer 21 and the reflection layer 23 not including the light absorption layer 22. FIG. 20 shows a comparison with the case (♦ in the figure) and the case of only the reflective layer 23 (▲ in the figure). According to this, the temperature-sensitive super-resolution medium (♦ and ▲ in the figure) can reproduce beyond the optical resolution limit (0.17 μm), and includes the light absorption layer 22 (● in the figure). ), Since the reproduction sensitivity is good, the resolution limit is further improved, and a reproduction signal up to 0.09 μm is obtained. Note that the reproduction parameters of the evaluation optical system are a wavelength of 408 nm and an objective lens aperture (NA) of 0.65.

  In the optical information recording media 2a, 2b, 2e, 2g, 2i, and 2k, the temperature sensitive layer 21 is provided on the back side of the surface of the recording layer 14 that is irradiated with the light beam. The temperature sensitive layer 21 may be provided on the recording layer 14 on the side irradiated with the recording / reproducing beam 32 (optical information recording media 2c, 2d, 2f, 2h, 2j, and 2l). In this case, although the reproduction sensitivity is inferior to that of the optical information recording media 2a, 2b, 2e, 2g, 2i, and 2k, a medium having higher durability than the configurations of Patent Documents 1 and 2 can be realized.

  Further, the optical information recording medium of the present invention further records the optical information recording media 2a to 2l on the side where the light is incident on the temperature sensitive reflective layer 13, that is, between the substrate 12 and the temperature sensitive reflective layer 13. The layer 14 may be laminated.

  In addition, this invention is not limited to each embodiment mentioned above, A various change is possible in the range shown to the claim. For example, the optical information recording medium of the present invention may be in the form of a card or a sheet as well as a disk-shaped, so-called disc-shaped optical disk. In the optical information recording medium of the present invention, the optical information recording method is not particularly limited as long as it is an optical method. The optical information recording medium of the present invention includes a magneto-optical disk, a phase change optical disk, etc. Various optical information recording media can be included.

  Further, the optical information recording medium of the present invention may be one in which the layer structure of Embodiment 1 or Embodiment 2 is repeatedly laminated. For example, the temperature-sensitive reflective layer 13 or the temperature-sensitive reflective layer 13 and the recording layer 14 are formed on two substrates, and these substrates are bonded so that the temperature-sensitive reflective layer 13 or the recording layer 14 faces each other. It can also be set as the structure which can perform light irradiation from the board | substrate side.

  Furthermore, embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. For example, the optical information recording medium of the present invention is a hybrid medium in which a reproduction-only surface having the same layer structure as in the first embodiment and a recording / reproducing surface having the same layer structure as in the second embodiment are mixed. It is good.

  Further, as the optical information recording / reproducing apparatus (optical information reproducing apparatus, optical information recording apparatus) for recording / reproducing with respect to the optical information recording medium according to the present embodiment, the optical information recording / reproducing apparatus shown in FIG. 21 is used. Can do. FIG. 21 is a block diagram showing a configuration of an embodiment of an optical information recording / reproducing apparatus according to the present invention.

  As shown in FIG. 21, the optical information recording / reproducing apparatus irradiates a spindle motor 91 for rotating the optical information recording medium 2, a recording / reproducing beam 32, and an optical pickup 92 that detects reflected light from the recording layer 14. A mechanical deck 93 that supports the spindle motor 91 and the optical pickup 92; a laser control circuit 94 that controls the laser power of the optical pickup 92; a servo mechanism 95 that moves the position of the mechanical deck 93 based on the output of the optical pickup 92; A recording system data control unit 96 that controls the laser power of the optical pickup 92 by controlling the laser control circuit 94 according to the information signal, and a medium signal detection circuit 97 that detects the information signal from the reflected light detected by the optical pickup 92. , An information processing circuit 9 for processing the information signal detected by the medium signal detection circuit 97 Includes an error detection system 99 for detecting an error of the information signal.

  The optical pickup 92 causes a recording / reproducing beam 32 (laser beam) to enter the recording layer 14 from the transparent resin layer 11 side using a laser light source (not shown) and an optical system such as a condenser lens 31. The optical pickup 92 irradiates the optical information recording medium 2 with the recording / reproducing beam 32 so that a high-temperature portion and a low-temperature portion are generated in the light beam spot in the temperature-sensitive layer 21. Decrease the transmittance at the part. The optical pickup 92 detects the reflected light from the recording layer 14 with an optical head (not shown).

  In the optical information recording / reproducing apparatus, the laser power of the optical pickup 92 is controlled by the laser control circuit 94, and the laser is irradiated onto the optical information recording medium 2 with high power during recording / erasing and with low power during reproduction. It is like that.

  In each of the above-described embodiments, the transmittance of the temperature sensitive layer 21 at the reproduction light beam wavelength is reduced as the temperature rises. However, for example, even in the temperature sensitive layer 21 having the transmittance characteristics shown in FIGS. 6 to 8, the transmittance may not necessarily decrease due to the temperature rise depending on the setting of the reproduction light beam wavelength. That is, in the case of the temperature sensitive layer 21 having the transmittance characteristics shown in FIGS. 15 to 17, the transmittance decreases at a high temperature at a wavelength of 405 nm, but when the reproduction light beam wavelength is set longer than that, the transmittance is reduced. May rise at high temperatures. The present invention is also effective when the reproduction light beam wavelength is set such that the transmittance increases at a high temperature. In other words, the temperature sensitive layer 21 may be one whose transmittance at the reproduction light beam wavelength increases as the temperature increases.

  In the optical information recording media 1 and 2 in which the transmittance of the temperature sensitive layer 21 at the reproduction light beam wavelength increases as the temperature rises, a high temperature portion and a low temperature portion are generated in the light beam spot in the temperature sensitive layer 21. By irradiating the light beam, the transmittance at the high temperature portion of the temperature sensitive layer 21 is increased, and the reflected light from the recording layer 14 is detected by an optical head (not shown), so that the high temperature portion of the temperature sensitive layer 21 is detected. Information can be reproduced by a method of reproducing information based on the transmitted light.

  In addition, when recording on the optical information recording medium 2 in which the transmittance of the temperature sensitive layer 21 at the reproduction light beam wavelength increases as the temperature rises, a high temperature portion and a low temperature portion are generated in the light beam spot in the temperature sensitive layer 21. In this way, by irradiating the light beam, the transmittance at the high temperature portion of the temperature sensitive layer 21 is increased, and the reflected light from the recording layer 14 is detected by an optical head (not shown). This can be performed by a method in which a minute region of the recording layer 14 is selectively heated by light transmitted through the portion.

  In the optical information recording medium 2 described above, the temperature sensitive layer 21 is provided on the back side of the surface of the recording layer 14 where the light beam is irradiated. However, the temperature sensitive layer 21 is a recording layer in the recording layer. You may provide in the side irradiated with the reproduction beam 32. FIG. In this case, although the reproduction sensitivity is inferior to that of the optical information recording medium 2, a medium having higher durability than that of Patent Documents 1 and 2 can be realized.

  In addition, a recording layer 14 is further laminated on the optical information recording medium 2 of the present invention on the light incident side of the temperature-sensitive reflective layer 13, that is, between the substrate 23 and the temperature-sensitive reflective layer 13. May be.

  In addition, this invention is not limited to each embodiment mentioned above, A various change is possible in the range shown to the claim. For example, the optical information recording medium of the present invention may be in the form of a card or a sheet as well as a disk-shaped, so-called disc-shaped optical disk. In the optical information recording medium of the present invention, the optical information recording method is not particularly limited as long as it is an optical method. The optical information recording medium of the present invention includes a magneto-optical disk, a phase change optical disk, etc. Various optical information recording media can be included.

  Further, the optical information recording medium of the present invention may be one in which the layer structure of Embodiment 1 or Embodiment 2 is repeatedly laminated. For example, the temperature-sensitive reflective layer 13 or the temperature-sensitive reflective layer 13 and the recording layer 14 are formed on two substrates, and these substrates are bonded so that the temperature-sensitive reflective layer 13 or the recording layer 14 faces each other. It can also be set as the structure which can perform light irradiation from the board | substrate side.

  Furthermore, embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. For example, the optical information recording medium of the present invention is a hybrid medium in which a reproduction-only surface having the same layer structure as in the first embodiment and a recording / reproducing surface having the same layer structure as in the second embodiment are mixed. It is good.

It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on one Embodiment of this invention. 1 is a schematic cross-sectional view showing an optical information recording medium according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing an optical information recording medium according to an embodiment of the present invention. It is a schematic sectional drawing which shows the optical information recording medium which concerns on other embodiment of this invention. 1 is a schematic cross-sectional view showing an optical information recording medium according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing an optical information recording medium according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing an optical information recording medium according to an embodiment of the present invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium shown in FIG. It is a fragmentary sectional view which shows the principal part of the optical information recording medium shown in FIG. It is a fragmentary sectional view which shows the principal part of the optical information recording medium shown in FIG. It is a fragmentary sectional view which shows the principal part of the optical information recording medium shown in FIG. It is a figure for demonstrating the mask effect by a temperature sensitive reflection layer, and has shown temperature distribution and reflectance distribution within the reproduction beam spot in a temperature sensitive reflection layer. It is a figure for demonstrating the mask effect by a temperature sensitive reflection layer, and has shown temperature distribution and reflectance distribution within the reproduction beam spot in a temperature sensitive reflection layer. It is a graph which shows an example of the temperature change of the spectral transmittance characteristic of a temperature sensitive layer. It is a graph which shows an example of a temperature change of the spectral reflectance characteristic with a temperature sensitive reflection layer without a light absorption layer, and shows a case where the temperature sensitive layer is thin and there is no minimum value due to the light interference effect. It is a graph which shows another example of the temperature change of a spectral reflectance characteristic with a temperature sensitive reflective layer without a light absorption layer, and shows the case where the temperature sensitive layer is thick and there is a local minimum due to the light interference effect. . It is a graph which shows another example of the temperature change of the spectral reflectance characteristic of the temperature sensitive reflective layer with a light absorption layer, the temperature sensitive layer is thick, and the local minimum due to the light interference effect exists on the shorter wavelength side than the reproduction wavelength. Shows when to do. It is a graph which shows another example of the temperature change of the spectral reflectance characteristic of the temperature sensitive reflective layer with a light absorption layer. The temperature sensitive layer is thick, and the minimum value due to the light interference effect exists on the longer wavelength side than the reproduction wavelength. Shows when to do. It is the graph which showed the reproduction resolution signal characteristic (C / N ratio) of the optical information recording medium which has a light absorption layer and a temperature sensitive layer compared with those without them. It is a block diagram which shows the structure of one Embodiment of the optical information recording / reproducing apparatus concerning this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on one Embodiment of this invention. It is the graph which showed CNR-reproduction power dependence of the recording mark length (0.14 micrometer) of the super-resolution area | region in the optical information recording medium which has a light absorption layer, a temperature sensitive layer, and a reflection layer or a heat insulation layer. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on other one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on other one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on other one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on other one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on other one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on other one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on other one Embodiment of this invention. It is a fragmentary sectional view which shows the principal part of the optical information recording medium which concerns on other one Embodiment of this invention.

Explanation of symbols

1a to 1f, 2a to 2l Optical information recording medium 11 Transparent resin layer 12 Substrate 13 Temperature sensitive reflective layer 14 Recording layer 21 Temperature sensitive layer 22 Light absorbing layer 23 Reflective layer 24 Heat insulating layer 30 Reproducing beam 31 Condensing lens 32 Recording / reproducing beam 33 reproduction beam spot 33a high temperature part 33b low temperature part 34 reproduction beam spot 34a high temperature part 34b low temperature part

Claims (16)

In an optical information recording medium for reproducing information recorded on a substrate by irradiation with a light beam,
A temperature-sensitive layer in which the reflectance and / or transmittance changes based on a change in temperature due to irradiation of the light beam;
A light absorption layer that changes the temperature of the temperature sensitive layer,
An optical information recording medium, wherein a substrate, a temperature sensitive layer, and a light absorbing layer are arranged in this order from the side irradiated with the light beam. In an optical information recording medium for reproducing information recorded on a substrate by irradiation with a light beam,
A temperature-sensitive layer whose reflectance and / or transmittance changes based on a change in temperature caused by irradiation with a light beam, and a light-absorbing layer that increases the temperature of the temperature-sensitive layer by absorbing the light beam and converting it into heat. And a heat insulating layer that makes the temperature rise of the temperature sensitive layer efficient,
An optical information recording medium comprising a substrate, a temperature sensitive layer, a light absorbing layer, and a heat insulating layer arranged in this order from the side irradiated with the light beam.   The temperature sensitive layer is configured to reflect and / or transmit the irradiated light beam based on the interference of the irradiated light beam between the reflected light on one surface of the temperature sensitive layer and the reflected light on the other surface. The optical information recording medium according to claim 1, wherein the rate changes.   In the temperature sensitive layer, the transmittance reduction region due to absorption at the short wavelength side at room temperature shifts to the long wavelength side or the short wavelength side according to an increase in the temperature range of the temperature sensitive layer, and at the wavelength of the reproduction light beam. The optical information recording medium according to claim 1, wherein the spectral transmittance and / or the spectral reflectance is changed.   5. The optical information recording medium according to claim 1, wherein the temperature-sensitive layer includes a metal oxide whose reflectance and / or transmittance changes with an increase in temperature.   6. The optical information recording medium according to claim 5, wherein the temperature sensitive layer contains zinc oxide.   The optical information recording medium according to claim 1, wherein the light absorption layer is a magneto-optical material.   7. The light according to claim 1, wherein the light absorption layer includes Si, Ge, AgInSbTe, GeSbTe, TbFeCo, DyFeCo, GdFeCo, or an alloy composed of two or more of these. Information recording medium.   The optical information recording medium according to claim 1, wherein the temperature sensitive layer and the light absorption layer are adjacent to each other.   10. The optical information recording medium according to claim 1, wherein the optical information recording medium is a reflection corresponding to a change in temperature of the temperature sensitive layer by the light beam and the light absorbing layer. An optical information recording medium capable of reproducing a minute recording mark below the diffraction limit of a reproducing light beam by utilizing a change in the rate and / or transmittance.   The method for reproducing an optical information recording medium according to any one of claims 1 to 10, wherein at least the temperature sensitive layer and the light absorbing layer are used to record a minute recording mark below the diffraction limit of the reproduced light beam. A method for reproducing an optical information recording medium, comprising reproducing.   The optical information recording medium according to claim 1 is irradiated with a light beam so that a high-temperature portion and a low-temperature portion are generated in a light beam spot in the temperature-sensitive layer. An optical information recording characterized in that the transmittance in the high temperature portion is reduced and the temperature of the high temperature portion is further heated by the light absorbing layer to reproduce information based on the light transmitted through the low temperature portion of the temperature sensitive layer. Media playback method.   The optical information recording medium according to claim 1 is irradiated with a light beam so that a high-temperature portion and a low-temperature portion are generated in a light beam spot in the temperature-sensitive layer. An optical information recording medium characterized by increasing the transmittance at a high temperature portion, further heating the temperature of the high temperature portion by a light absorption layer, and reproducing information based on the light transmitted through the high temperature portion of the temperature sensitive layer How to play. In an optical information recording medium for reproducing information recorded on a substrate by irradiation with a light beam,
In order from the incident side of the light beam,
Substrate, ZnO, ZnS, SnO ₂ , CeO ₂ , NiO ₂ , In ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , VO ₂ , SrTiO ₃ film, Si, Ge, AgInSbTe, GeSbTe, TbFeCo, An optical information recording medium comprising: a film made of either DyFeCo or GdFeCo. In an optical information recording medium for reproducing information recorded on a substrate by irradiation with a light beam,
In order from the incident side of the light beam,
Substrate, ZnO, ZnS, SnO ₂ , CeO ₂ , NiO ₂ , In ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , VO ₂ , SrTiO ₃ film, Si, Ge, AgInSbTe, GeSbTe, TbFeCo, An optical information recording medium comprising a film made of either DyFeCo or GdFeCo and a film made of either SiN or AlN.   Using the optical information recording medium according to any one of claims 1 to 10 and 14 to 15 and the reproducing method according to any one of claims 11 to 13, the diffraction limit of the reproducing light beam is below the diffraction limit. An optical information reproducing apparatus for reproducing information of a minute recording mark.

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