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Method of evaluating optical information mediumMethod of evaluating optical information medium description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060203242, Method of evaluating optical information medium. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of U.S. application Ser. No. 11/074,762, filed Mar. 9, 2005, which is a continuation application of PCT/JP2004/003221, filed Mar. 11, 2004, which was published under PCT Article 21(2) in Japanese, which claims priority to Japanese Application No. 2003-074553, filed Mar. 18, 2003, the entire contents of each of which are incorporated herein by reference. TECHNICAL FIELD [0002] The present invention relates to a method for evaluating an optical information medium, and more specifically, to a simple method for evaluating an optical information medium by judging the surface quality of the medium by the use of a novel artificial fingerprint liquid as an evaluation dispersion liquid. BACKGROUND ART [0003] When an optical disk such as a reproduction-only optical disk, optical recording disk, magneto-optical recording disk, and the like, is used, the adhesion of stains or fingerprints to the surface thereof is caused on the basis of various stain materials. The adhesion of these stains or fingerprints is unpreferable, and in some cases, the surface of the optical disk is subjected to an appropriate surface treatment in order to improve an anti-staining property thereof, decrease a fingerprint adhering property or improve a fingerprint removing property. [0004] For example, investigations are being made on various water repellent or oil repellent treatments to the surface of the optical disk. In order to check the effect of improving the anti-staining property by the surface treatments, in many cases, there is used a manner of adhering a fingerprint actually onto the optical disk surface and, then, evaluating the wiping-off property thereof with the naked eye. However, such an evaluating manner is poor in quantitativeness and reproducibility. [0005] On the assumption that if the water repellency or the oil repellency of the optical disk surface is high, stain materials are easily removed, the following is frequently performed: measurement of the contact angles of various liquids, such as water and aliphatic hydrocarbons, to the above treated-surface. However, the evaluation based on the contact angle or surface free energy is, in a sense, an indirect evaluating manner. Accordingly, it can be properly used as a manner for evaluating the anti-staining property in only a highly restricted case where the above-mentioned assumption that if the water repellency or the oil repellency is high, excellent anti-staining property is exhibited comes into effect. This evaluating manner gives only a relative evaluation result at best. In other words, when this evaluating manner is applied to an optical disk surface, it is substantially impossible that a threshold value which represents whether or not the disk can be used without causing any practical problem is determined for the contact angle or surface free energy. [0006] In recent years, it has been desired that about optical information media the recording density thereof is made higher in order to store a mass of data such as moving image data. Thus, researches and developments are being actively made for making the density of recording capacity higher. As one of them, the following suggestion is made: as seen in, for example, a DVD, the recording/reproducing wavelength thereof is made short and the numerical aperture (NA) of the objective lens is made large, thereby making the condensed spot diameter of the reproducing/reproducing beam small. As compared with a CD, a recording capacity (4.7 GB/surface) 6 to 8 times that of the CD is actually attained by changing the recording/reproducing wavelength from 780 nm to 650 nm and changing the numerical aperture (NA) from 0.45 to 0.60. Recently, as a method for recording high-quality moving images for a long time, an attempt has been made to make the recording/reproducing wavelength short up to about 400 nm and making the numerical aperture high up to 0.85, so as to attain a recording capacity 4 times or more that of DVD. [0007] However, when the recording density is made high in this way, the condensed spot diameter of the recording/reproducing beam becomes small. Consequently, the recording medium-becomes more sensitive to dust, dirt, fingerprints or the like adhering to the laser beam incident side surface of the medium than the conventional art. In particular, about stains containing an organic material, such as fingerprints, a large effect is produced when the stains adhere to the laser beam incident-side surface. Since the stains are not easily removed, many countermeasures have been considered so far. [0008] For example, Japanese Laid-open Patent Publication Nos. 10-110118 (1998) and 11-293159 (1999) suggest that when a hard coat agent coated film is formed on a surface of an optical disk substrate made of polycarbonate or the like, a non-crosslinking type fluorine type surfactant is incorporated into the hard coat agent. In order to evaluate the anti-staining property of the hard coat surface of the optical disk, there is performed an operation of adhering an artificial fingerprint liquid wherein a small amount of sodium chloride, urea and lactic acid is dissolved in a mixture solution of water and ethanol onto the surface of the hard coat under pressure, using a pseudo fingerprint, and then determining the wiping-off property thereof with the naked eye. This artificial fingerprint liquid is a liquid described in JIS K2246: 1994 "Rust Preventing Oil". The JIS standard prescribes a performance-testing method for rust preventing oils used for temporary rust-prevention of metal materials such as steel. Accordingly, the artificial fingerprint liquid is prepared to determine the corrosiveness of metal materials. For this reason, the liquid is not useful at all for purposes other than this. Even if the artificial fingerprint liquid made mainly of water and ethanol is adhered onto a surface of an optical disk substrate made of resin such as polycarbonate, in reality the artificial fingerprint liquid is repelled and is not fixed on the substrate surface in almost all cases. It can be considered from this fact that the resin substrate surface exhibits the same wiping-off property against the artificial fingerprint liquid whether the surface is not subjected to any surface treatment or is subjected to surface treatment. That is, it is hardly significant to use the artificial fingerprint liquid prescribed in LIS K2246: 1994 for evaluation of the anti-staining property or the fingerprint removing property of an optical disk surface. [0009] From such an actual-situation, it is desired to develop an artificial fingerprint liquid for quantitatively and with a good reproducibility evaluating the surface quality of an optical disk. It is also desired to develop a simple evaluating method for quantitatively and reproducibly judging the surface quality of an optical disk by the use of the artificial fingerprint liquid. DISCLOSURE OF THE INVENTION Objects of the Invention [0010] Thus, an object of the present invention is to solve the above-mentioned problems of the conventional art and provide a simple method for evaluating an optical information medium by judging quantitatively and reproducibly the surface quality of the optical information medium by the use of a novel artificial fingerprint liquid as an evaluation dispersion liquid. SUMMARY OF THE INVENTION [0011] The present invention comprises the following inventions. [0012] (1) A method for evaluating an optical information medium, comprising the steps of: [0013] adhering, under predetermined conditions, an evaluation dispersion liquid containing a fine-particle-form substance and a dispersion medium capable of dispersing the fine-particle-form substance onto the surface of the optical information medium which is on the incident side of a recording and/or reproducing beam; [0014] measuring an area ratio of the medium surface occupied with the evaluation dispersion liquid droplets adhered per unit area of the medium surface; and [0015] judging the optical information medium as an acceptable medium when the measured area ratio is 6% or less. [0016] (2) A method for evaluating an optical information medium, comprising the steps of: [0017] adhering, under predetermined conditions, an evaluation dispersion liquid containing a fine-particle-form substance and a dispersion medium capable of dispersing the fine-particle-form substance onto the surface of the optical information medium which is on the incident side of a recording and/or reproducing beam; [0018] measuring a recording and/or reproducing characteristic of the medium with the evaluation dispersion liquid droplets adhered to the medium surface; and Continue reading about Method of evaluating optical information medium... Full patent description for Method of evaluating optical information medium Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method of evaluating optical information medium patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. 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