JP3034497B2 - Information recording / reproducing / erasing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel information recording method, and more particularly, to a spectral reflectance when a high energy is applied and a spectral reflectance when a low energy is applied. The present invention relates to an erasable information recording device for recording information by changing the information to a higher value. 2. Description of the Related Art In recent years, various information recording / reproducing methods have been developed as information recording density and digitization progress. In particular, optical disks utilizing laser light energy for recording, erasing, and reproducing information are mining rare metal Nos.
80, 1983 (optical disks and materials), a higher recording density is possible than magnetic disks, and this is a promising method for information recording in the future. Among them, a reproducing apparatus using a laser has been put to practical use as a compact disk (CD). On the other hand, the recordable methods are roughly classified into two types: a write-once type and a rewritable type. The former can only be written once and cannot be erased. The latter is a method capable of repeatedly recording and erasing. In the write-once recording method, the medium at the recording portion is destroyed or formed by laser light to form irregularities, and reproduction uses the change in the amount of light reflection due to the interference of the laser light at the irregularities. For this recording medium, it is generally known to use Te or an alloy thereof to form irregularities by melting and sublimation. This type of medium has some problems such as toxicity. Magneto-optical materials are mainly used as rewritable recording media. This method uses optical energy to invert the local magnetic anisotropy of the medium near the Curie point or the compensation point temperature, and records the magnetic anisotropy.
Reproduction is performed using the amount of rotation of the polarization plane due to the force-effect . This method has been vigorously researched and developed with the aim of putting it into practical use in a few years, as the amount of rewritable type is also promising. However, at present, there is a large problem that there is no material having a large rotation amount of the polarization plane, and the output level such as S / N and C / N is small even if various measures such as multi-layer film formation are performed. As another rewritable type system, there is a system that utilizes a change in reflectance due to a reversible phase change between amorphous and crystalline recording media. [0003] For example, National Technical Report Vol.
9. No. 5 (1983) p. 82. A thin film obtained by adding a small amount of germanium (Ge) and (Sn) to TeOx described in No. 82 becomes amorphous by irradiating a short-pulse laser beam with a high power density, and has a higher reflectance than a non-irradiated portion of the laser beam. Is recorded by decreasing the Conversely, erasing is used by irradiating a laser beam with a low power density to crystallize and raise the reflectance higher than that of the recording portion. [0004] As in the prior art, the reflectance
The case of recording by lowering the Ku changes such dust on the disc, the dust adheres, it acts in a direction to lower the reflectance. Thus the recorded signal, dust, by dust, the signal level will be reduced. It is an object of the present invention to provide an information recording apparatus using a recording medium utilizing a change in crystal structure and capable of preventing a signal level from being reduced by dust or the like. [0006] In order to achieve the above object,
According to the present invention, the following information recording device is provided.
Is done. That is, an optical disk and the optical disk
A light source for inputting light energy to the light,
The disk includes a substrate and a recording medium provided on the substrate.
Having a predetermined threshold value from the light source.
State 1 after the high intensity light energy is applied,
Light energy of a predetermined intensity lower than the threshold is input.
State 2 that is different from the state 1 after the
The reflectance (R _W ) for light of a predetermined wavelength in state 1 is
From the reflectance (R _E ) for the light having the wavelength in the state 2,
The information recording device is characterized in that the information recording device has a higher [0008] The present invention uses a recording medium having a crystal structure different Tsu in a state of low energy and cooling after introduction of high energy lower intensity than the intensity cooled state after turning the predetermined intensity, high energy Information is recorded by changing the spectral reflectance in a state of cooling after inputting to be higher than that in a state of cooling after inputting low energy . [0009] The recording medium according to the present invention is characterized in that, by applying energy in a solid state, at least 2
It has a kind of reflectance and can change the spectral reflectance reversibly, especially the spectral reflectance in the state of cooling after inputting high energy, and the reflectance in the state of cooling after inputting low energy It is a recording medium that can change higher than the above. [0010] In the present invention, a recording medium that the reflectivity R _W after high energy input is greater than the reflectivity R _E after low energy _{input, R E <R W <γR} E + (1-γ), 0 <Γ <1 (1) When the expression (1) is satisfied, the recording medium can be recorded and erased. Here, γ is the ratio of the effective energy required to obtain the low reflectance state and the high reflectance state. This relationship is derived as follows. That is, there is a relationship of the formula (2) between the externally input energy P and the effective energy Q actually input to the medium. P (1-R) = Q (2) In a medium having a reflectance R, energy of P * R is reflected and is not actually input to the medium. Therefore, charged with high reflectivity R _W and a low energy state which supplied the high energy
Equation (3) holds between the low reflectance R _{E in} the closed state . ## EQU1 ## Here, since P _W > P _E, from equation (3), (1)
An expression is obtained. FIG. 1 shows the range obtained from the equation (1). A hatched portion in FIG. 1 indicates a state in which recording and erasing can be performed. In this case, it is desirable that the difference in reflectance between R _W and R _E is large, considering that the output of reproduction is good. Especially in the case of R _W ≧ 1.3R _E, particularly good reproduction output is obtained, a large S / N can be obtained. This range is a portion shown with a mesh pattern in FIG. γ is the ratio of the Q _E and Q _W, in effect can be approximated with the heating temperature of the recording medium the reflectivity of R _W and R _E are obtained. Substantially, it can be approximated as a temperature at which a change in reflectance can occur. The recording medium of the present invention is suitable for those in which the above relationship is satisfied, but is also suitable for a material having a crystal-crystal phase transition. The recording medium of the present invention is characterized in that at least one element of group Ib of the periodic table and a group IIb, group IIIb, group IVb and V
A material made of an alloy with at least one selected from group b elements is preferable. Among these alloys, alloys containing copper as a main component and Al, Ga, In, Ge and Sn are preferable, and Ni, Mn, and F are used as the third elements in these alloys.
Alloys containing e and Cr are preferred. Further, Al, Cd and Z are mainly composed of silver.
Alloys containing n are preferable, and alloys containing Cu, Al, and Au as the third element in these alloys are more preferable. An alloy containing gold as a main component and containing Al is preferable. The alloy of the present invention comprises the group Ib element and the group IIb, III
Those having an intermetallic compound with a group b, IVb or Vb element are preferred. That is, the alloy according to the present invention has different phases of crystal structure in at least two temperature ranges in a solid state, and has at least two different reflectivities at the same temperature by heating and cooling in the solid state. And can reversibly change the reflectance. The present invention can be applied to an apparatus in which a thin film of a recording medium is provided on a substrate provided with a tracking groove. The recording medium has a first state higher than room temperature in a solid state.
Has a temperature (high temperature) and a first temperature lower than the temperature (low temperature) crystal structure different in the state, by quenching from the high temperature metal having a different crystal structure than that an equilibrium phase at room temperature Or it is preferable to be comprised with an alloy. The alloy according to the present invention has at least two spectral reflectance at the same temperature by rapid cooling from a high temperature solid state is one that can be varied reversibly spectral reflectance. That is, the alloy according to the present invention has a phase having a different crystal structure in at least two temperature ranges in a solid state,
Among them, the spectral reflectance differs between the quenched state of the high-temperature phase and the low-temperature phase state of the non-quenched standard state. It changes reversibly. The principle of the change in the reversible reflectance according to the present invention will be described with reference to FIG. The figure is a phase diagram of an XY binary alloy in which an α solid solution, a β intermetallic compound, and a γ intermetallic compound are present. Taking an alloy of ABx composition as an example, the alloy in the solid phase, beta single phase, may take a (beta + gamma) phase and (alpha + gamma) phase. The crystal structure differs in the single-phase state of α, β, and γ, and the single and mixed phases have different optical properties, for example, different spectral reflectances. Such alloys are at T ₁ temperature, typically room temperature, but have (α
+ Γ) phase is stable. When heating and quenching it to T ₄ temperature β-phase is rapidly cooled to T ₁ temperature. This state is (α +
Since it is different from the γ) phase, the spectral reflectance also differs. When this quenched β-phase alloy is heated is cooled to T _e temperature below T ₂ temperature β-phase is transformed to (α + γ) phase, the spectral reflectance is returned to the initial state. By repeating such two heating and cooling processes, it is possible to reversibly change the spectral reflectance. The alloy examples of the recording medium of the present invention are as follows. Silver as a main component, zinc 30 to 46 wt%,
Alloy containing one kind of aluminum of 6 to 10 wt%, copper as a main component, alloy containing one kind of aluminum of 10 to 20 wt%, indium of 20 to 40 wt%, tin of 16 to 35 wt%, gold as a main component, aluminum of two Alloys containing 0.5-5 wt% or a small amount of VIII, Ib, II
It may contain one or more of the elements of groups b, IIIb, IVb, Vb, VIa, VIIa. Its content is preferably 10w
t% or less. The recording density is 20 megabits / cm ²
For producing information in a small area as described above, 0.01
The thickness is preferably 0.2 to 0.2 μm. It is effective that the recording layer is directly cooled and solidified from a gas phase or a liquid phase into a predetermined shape. These methods include a PVD method (evaporation, sputtering method, etc.), a CVD method, and a method using a member having high thermal conductivity for rotating a molten metal at high speed. In particular, there are a molten metal quenching method in which a molten metal is poured onto a circumferential surface of a metal roll and rapidly solidified, an electroplating method, a chemical plating method, and the like. When a powdery material is used, it is effective to apply it on a substrate and adhere it to the substrate. When applying, a binder that does not cause a reaction or the like even when the powder is heated is preferable. It is also effective to coat the surface of the material, the film formed on the substrate, or the surface of the coating layer in order to prevent the material from being oxidized by heating. The powder is preferably formed by a atomizing method in which the molten metal is sprayed together with a gaseous or liquid refrigerant, and then injected into water and rapidly cooled. Its particle size is 0.
It is preferably 1 mm or less, particularly preferably ultrafine powder having a particle size of 1 μm or less. The film is formed by evaporation, sputtering, C
It can be formed by VD electroplating, chemical plating or the like. In particular, sputtering is preferable for forming a film having a thickness of 0.1 μm or less. Spatter ring can be easily controlled target alloy composition. As means for recording information and the like, electric energy in the form of voltage and current, electromagnetic waves (visible light, radiant heat, infrared rays, ultraviolet rays, light of a photographic flash lamp, electron beam, proton beam, argon laser, semiconductor laser) Laser beam, etc.
Heat) can be used, and it is particularly preferable to use it for an optical disk utilizing a change in spectral reflectance due to the irradiation. Optical disks include digital audio disks (DAD or compact disks), video disks,
There is a memory disk and the like, and these can be used. The recording medium of the present invention can be used for each of a read-only type, an additional recording type, and a rewritable disk device, and is particularly effective for a rewritable disk device. An example of the principle of recording and reproduction of an optical disk according to the present invention is as follows. First, the recording medium is locally heated and, by rapid cooling after the heating, the crystal structure in the high temperature region is held in the low temperature region to record predetermined information, or locally heated based on the high temperature phase. In the high-temperature phase, information is locally recorded in the low-temperature phase, and the recorded portion is irradiated with light to detect a difference in optical characteristics between the heated portion and the non-heated portion, thereby reproducing information. Further, the part recorded as information can be heated at a temperature lower or higher than the heating temperature at the time of recording to erase the recorded information. The light is preferably a laser beam, particularly preferably a short wavelength laser. The reflectance between the heated part and the non-heated part of the present invention is 500 nm or 80.
Since it is the largest at a wavelength near 0 nm, it is preferable to use laser light having such a wavelength for reproduction. The same laser source is used for recording and reproduction, and it is preferable to irradiate another laser beam having a lower energy density than that of the recording for erasing. [Table 1] (Embodiment 1) A recording medium having a thickness of about 100 nm was formed on a 1.2 mmt SiO ₂ glass substrate by a sputtering method. This two-layer film is recorded from the recording medium film side using a laser beam,
Then, erasure was performed. After recording and erasing, 200-15
FIG. 2 shows an example of the spectral reflectance at a wavelength of 00 nm. Table 1 shows the results of measuring the reflectance (%) of various alloy thin films at the light source wavelength of 830 nm during recording and erasing.
A high recording temperature corresponds to a high energy input, and a low erasing temperature corresponds to a low energy input. All the alloy thin films shown in Table 1 satisfied the recording and erasing conditions. The alloy composition in the table is% by weight. Recording temperature is 350
Adjusting the power of the laser beam so that ° C., erasing temperature was adjusted by differential Okasu the laser beam to be 0.99 ° C.. According to the present embodiment, a high S / N ratio can be obtained. [Table 1] (Embodiment 2) An Ag-40 wt% Zn alloy thin film is used as a recording medium,
Disks were produced with the film configurations shown in Table 2. Recording and erasing were performed using a semiconductor laser having a wavelength of 830 nm, and the reflectance after recording and after erasing was measured at a light source wavelength of 830 nm. The results are shown in FIG. Recording conditions of 1 to 12 satisfied the recording and erasing conditions. Among them, No. 8
The best characteristics were shown up to １２12. In addition, No. No. 13 satisfied the recording conditions but did not satisfy the erasing conditions. However, even in such a case, Ta _{2 is used} as an interference film for laser light.
The thickness of the O ₅ by devising the, No. In the situation shown in FIG. 5, the erasing condition can be satisfied. In this case, by optimizing the thickness of Ta ₂ O ₅ , interference as shown in FIG. 4 was caused, and the reflectance after recording and after erasing could be reduced. It should be noted that, in Table 2, The films using CrO _x films as the heat absorbing films shown in 10 to 12 satisfy the recording and erasing conditions by the effect of lowering the reflectance and the effect of heat absorption as shown in FIG. The recording and erasing temperatures were adjusted by adjusting the laser beam so that the temperatures were the same as in the first embodiment. [Table 2] Embodiment 3 A glass substrate of 1.2 mmt is used as a substrate, an Ag-40 wt% Zn film having a thickness of 70 nm is used as a recording film, and a CrO _x having a thickness of 10 nm is used as a heat absorbing layer and SiO is used as a transparent layer.
₂ was fabricated disk as shown in FIG. 6 described in 200nm thickness, the recording and erasing and the results repeated was performed on the recording method of the present invention for the recording medium formed on the glass substrate 1 in the semiconductor laser 5, what No problem even at times
It was confirmed that the initial characteristics were maintained. In the figure, 1 is a glass substrate, 2 is a recording medium, 3 is a heat absorbing layer, and 4 is a transparent layer as a protective film. According to the present invention, a change in crystal structure is utilized.
Signal level decreases due to dust, etc.
It is possible to provide an information recording device that can prevent
Wear.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram that can be used in the information recording apparatus of the present invention .
4 is a graph showing a relationship between spectral reflectances at the time of recording / erasing of a recording medium . FIG. 2 is used in an information recording apparatus according to an embodiment of the present invention .
7 is a graph showing spectral reflectance characteristics of a recording medium that can be used . FIG. 3 is used in an information recording apparatus according to an embodiment of the present invention .
5 is a graph showing the relationship between the spectral reflectances at the time of recording / erasing of an alloy film of a recording medium which can be performed . FIG. 4 is used in an information recording apparatus according to an embodiment of the present invention .
9 is a graph showing spectral reflectance characteristics when an interference film is used as a recording medium that can be used . FIG. 5 is used for an information recording apparatus according to an embodiment of the present invention .
9 is a graph showing spectral reflectance characteristics when a heat absorbing film is used as a recording medium that can be used . [6] the laser beam to the optical disc of one embodiment of the present invention
Explanatory diagram showing that recording and reproduction are performed by irradiating . FIG. 7 shows a record that can be used in the information recording apparatus of the present invention .
FIG. 3 is an explanatory diagram showing a binary phase diagram of an alloy constituting the recording medium. [Description of Signs] 1 substrate 2 recording medium 3 heat absorbing layer 4 transparent layer 5 laser beam

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuo Ito 3-1-1 Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Shoichi Nagai 3-1-1 Sachimachi, Hitachi-shi, Ibaraki No. 1 Hitachi, Ltd. Hitachi Research Laboratories (72) Inventor Ryuji Watanabe 3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Hitachi Research Laboratories (72) Inventor Seiki Shimizu 3, Hitachi City, Hitachi City, Ibaraki Prefecture No. 1-1, Hitachi, Ltd. Hitachi Research Laboratory (56) References JP-A-55-129939 (JP, A) JP-A-59-144049 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 7/24 522

Claims (1)

(57) [Claims] A light source unit, wherein the light source unit stores the light on an optical disk mounted on the device.
The optical disk is used for recording and erasing information on the disk.
Light energy is applied to the disc to
Irradiation of reproduction light for reproduction is performed, and the optical disc includes a substrate and a recording medium provided on the substrate.
A recording medium film , and the recording medium film has a property from the light source section as a property.
Received the light energy until the temperature reached 1.
The first phase changes to the first phase, wherein the first phase is
Said light energy reaching a second temperature lower than the temperature of 1
Changes to the second phase when receiving
And the reflectance of the first phase for the reproduction light is
2 higher than the reflectance for the reproduction light of the second phase,
Record information by the change from the second phase to the first phase,
The information is erased by the change from the first phase to the second phase.
An information recording / reproducing / erasing apparatus characterized by being deleted. 2. The information recording / reproducing / erasing device according to claim 1,
The reflectance of the first phase for the reproduction light is R _W ,
In the second phase, the light of the wavelength used for the reproduction
If the set to R _E Iritsu, R _W and R _E is the information recording reproducing erasing instrumentation to satisfy the relationship of R _W ≧ 1.3R _E
Place.