WO2002099791A1

WO2002099791A1 - Method of measuring chracteristic data for multilevel optical recording medium, and evaluation method for multilevel optical recording medium

Info

Publication number: WO2002099791A1
Application number: PCT/JP2002/005518
Authority: WO
Inventors: Hiroyuki Arioka; Syuji Tsukamoto; Takashi Horai
Original assignee: Tdk Corporation
Priority date: 2001-06-05
Filing date: 2002-06-04
Publication date: 2002-12-12
Also published as: JP2002367237A

Abstract

A method of measuring characteristic data for a multilevel optical recording medium, comprising measuring (steps 31-33) characteristic data for a multilevel optical recording medium (1) by using a two-value recording/reproducing evaluation device. This multilevel optical recording medium (1) is so produced as to be capable of multilevel recording with light reflectance with respect to a reproducing laser beam controlled in multiple stages by switching at least one of a recording laser beam irradiation time and an irradiation power and by changing the transmittance of a recording layer (12) by a recording laser beam. Accordingly, since characteristic data for a multilevel optical recording medium (1) can be measured without newly purchasing or producing a dedicated multilevel recording/reproducing evaluation device, the measuring costs can be reduced.

Description

Itoda »

Method for measuring characteristic data of multi-level optical recording medium and evaluation method for multi-level optical recording medium

Technical field

The present invention relates to a measuring method for measuring characteristic data of a multilevel optical recording medium capable of multilevel recording in one virtual recording cell, and a multilevel optical recording medium based on the characteristic data measured by the measuring method. It is related to the evaluation method for evaluating. -Background technology

Currently, as an optical recording medium, binary data is recorded by irradiating a recording laser beam to form pits, and the binary data can be reproduced based on the presence or absence of the pits. Value optical recording media are widely used. In recent years, in response to a request for an increase in the recording density of an optical recording medium, a study for adjusting the focused beam diameter of a recording laser beam to perform high-density recording has been advanced. On the other hand, unlike the method of adjusting the focused beam diameter, the development of a multi-level optical recording medium that can record one of a plurality of different meaningful marks in one virtual recording cell is underway. In this multi-level optical recording medium, for example, by changing the irradiation amount of the recording laser beam to multiple stages, a part of one virtual recording cell to be recorded in the optical recording medium that has a deteriorated portion (light-transmissive portion) is reduced. In the following, this is also called the “recording mark”), and the ratio of the recording mark to the entire virtual recording cell depends on the irradiation amount of the recording laser beam. In other words, in this multilevel optical recording medium, when the reproduction laser beam is irradiated, the light transmittance of the virtual recording cell where the recording mark is formed is affected, and as a result, the light of the reproduction laser beam is irradiated. The reflectivity is multi-step (for example, 5 steps or more),. Therefore, it is necessary to associate each of a plurality of data contents with each of the multi-stage light reflectances. As a result, any one of a plurality of data is recorded in one virtual recording cell

. In this case, the light transmittance is the ratio of the laser beam passing through the virtual recording cell to the reproducing laser beam irradiated on the virtual recording cell, and the light reflectance is the virtual recording cell. The irradiated reproduction laser beam passes through this virtual recording cell, is reflected by the reflective layer of the multi-level optical recording medium, and then passes through the virtual recording cell again and is emitted outside the multi-level optical recording medium. Laser beam rate.

On the other hand, multi-level recording is possible only after the multi-level optical recording medium controls the light reflectivity of each virtual recording cell in multiple steps. For example, the light reflectivity of the unrecorded portion and the recording laser beam Unless the dynamic range corresponding to the difference from the light reflectance of the recording portion with the largest irradiation amount is large to some extent, multilevel recording becomes difficult. For this reason, the recording layer used for the multi-level optical recording medium is made of a material suitable for multi-level recording, such as a wide dynamic range of light reflectivity to cope with multi-step irradiation by the recording laser beam. Must be selected. Therefore, when selecting this material, the characteristic data such as the dynamic range of the light reflectance of various multi-level optical recording media to be evaluated in which the recording layer is formed of various materials is measured, and based on the characteristic data, It is necessary to evaluate the quality of the multilevel optical recording medium to be evaluated. Also, at the time of manufacturing a multi-level optical recording medium, the recording data can be normally reproduced in a multi-level optical recording medium in a reproducible manner by using a dedicated multi-level recording / reproducing evaluation apparatus for each manufacturing lot. Need to be evaluated. Disclosure of the invention

The inventor has found the following points to be improved as a result of examining the above-described conventional technology. That is, at present, as a device for measuring and evaluating characteristic data of an optical recording medium, a binary recording / reproducing evaluation device for evaluating a binary optical recording medium is mainly used. Used. For this reason, if it is necessary to use a dedicated multi-level recording / reproduction evaluation device to measure and evaluate the characteristic data of the multi-level optical recording medium, the manufacturer of the optical recording medium must use a dedicated multi-level recording / reproduction evaluation. Equipment must be newly purchased or manufactured. Even if a manufacturer already owns a multi-level recording / reproducing evaluation device, it is necessary to purchase or manufacture a new multi-level recording / reproducing evaluation device to further increase the production of multi-level optical recording media. There is. For this reason, despite the superior recording method, it is necessary to reduce the manufacturing cost of the multi-level optical recording medium due to the rise in the characteristic data measurement cost and the evaluation cost due to the purchase of a new evaluation device. It will be difficult. Therefore, it is preferable to improve this point.

The present invention has been made to solve the above-described points to be improved, and has as its main object to provide a method for measuring characteristic data of a multilevel optical recording medium that can reduce the measurement cost. Another object of the present invention is to provide an evaluation method for a multi-level optical recording medium that can reduce the evaluation cost.

The method for measuring characteristic data of a multi-level optical recording medium according to the present invention is a measuring method for measuring characteristic data of a multi-level optical recording medium manufactured to enable multi-level recording. The characteristic data of the multi-level optical recording medium is measured using a reproduction evaluation device. It should be noted that the multi-level optical recording medium of the present invention includes both a multi-level optical recording medium as a sample manufactured in a development stage and a multi-level optical recording medium actually manufactured as a product.

In this case, in the multi-level optical recording medium, by switching at least one of the irradiation time and the irradiation power of the recording laser beam, the light reflectance with respect to the reproducing laser beam is controlled in multiple stages, and multi-level recording is performed. Preferably, it is manufactured as possible. Further, the multi-level optical recording medium may be configured such that the transmittance of the recording layer is changed by one beam of the recording laser, whereby It is preferable that the light reflectance for the one beam is controlled in multiple stages. Further, it is preferable that the multi-level optical recording medium is configured so that the light reflectance with respect to the reproduction laser beam can be controlled to five or more steps.

In the method of measuring characteristic data of these multi-level optical recording media, the characteristic data of the multi-level optical recording medium is measured using an existing binary recording / reproducing evaluation device, and a dedicated multi-level recording / reproduction evaluation device is used. Since the characteristic data of the multi-level optical recording medium can be measured without purchasing or manufacturing a new one, the measurement cost can be reduced. Therefore, the manufacturing cost of the multi-level optical recording medium can be sufficiently reduced.

Also, predetermined data is recorded on the multi-level optical recording medium by the binary recording / reproducing evaluation device, and the characteristic data of an unrecorded part and a recorded part of the recorded multi-level optical recording medium are recorded. It is preferable to measure. By performing the measurement in this manner, it is possible to measure accurate characteristic data of the actually recorded multilevel optical recording medium. Therefore, for example, when evaluating the quality of a multilevel optical recording medium, the reliability of the evaluation can be improved.

The evaluation method of the multi-level optical recording medium according to the present invention is based on the characteristic data measured by the characteristic data measuring method for any one of the above-described multi-level optical recording media. Evaluate multi-level optical recording media.

In this evaluation method for a multilevel optical recording medium, a special multilevel optical recording medium is evaluated based on characteristic data measured using an existing binary recording / reproduction evaluation apparatus. Since the multilevel optical recording medium can be evaluated without newly purchasing or manufacturing an apparatus, the evaluation cost can be reduced. Therefore, the manufacturing cost of the multi-level optical recording medium can be sufficiently reduced.

In this case, the measured characteristic data and the multi-level optical recording medium measured by the binary recording / reproduction evaluation device and the multi-layer recording / reproduction evaluation device, respectively. It is preferable to evaluate the quality of the multi-level optical recording medium based on a correlation previously obtained with respect to both characteristic data of the body. By performing the evaluation in this manner, the quality of the multi-level optical recording medium can be accurately evaluated.

Further, it is preferable that the quality of the multi-level optical recording medium is evaluated by comparing reference characteristic data obtained in advance based on the correlation with the characteristic data measured by the binary recording / reproducing evaluation device. . With such an evaluation, the quality of the multi-level optical recording medium can be evaluated in a short time.

This disclosure relates to the subject matter included in Japanese Patent Application No. 2001-169699, filed on June 5, 2001, All are expressly incorporated herein by reference. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a partially cutaway perspective view showing the configuration of an optical recording medium 1 according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram conceptually showing the recording marks M a to M g recorded on the optical recording medium 1.

FIG. 3 is a characteristic diagram showing the relative light reflectance characteristics of the optical recording medium 1 using various organic dyes.

FIG. 4 is a characteristic diagram showing relative light reflectance characteristics of Samples 1 to 3 using different types of organic dyes.

FIG. 5 is a flowchart of the medium evaluation process 30.

FIG. 6 is a block diagram showing the configuration of the binary recording / reproduction evaluation device 40. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, with reference to the accompanying drawings, a method of measuring characteristic data of a multi-level optical recording medium according to the present invention and a method of evaluating a multi-level optical recording medium will be described. A preferred embodiment will be described.

First, the configuration of a multilevel optical recording medium 1 to be evaluated in the present invention (hereinafter, also referred to as “optical recording medium 1”) will be described with reference to FIG.

The optical recording medium 1 is a CD-R type optical recording medium (write-once optical recording medium). As shown in FIG. 1, a substrate 11, a recording layer 12, a reflective film 13, and a protective layer 14 are provided. It is configured with. The substrate 11 is formed in a disk shape using a transparent resin as a base material. On one surface (upper surface in FIG. 1) of the substrate 11, a laser beam guide group 11 a and a land 11 b are spirally formed from the vicinity of the center to the outer edge. ing. The recording layer 12 is formed using organic dyes such as cyanine, merocyanine, methine dyes and derivatives thereof, benzenethiol metal complexes, phthalocyanine dyes, naphthalocyanine dyes, and azo dyes. It is formed by coating so as to cover 11a and land 11b. The recording layer 12 is decomposed and deteriorated by the irradiation of the recording laser beam by the recording device, and the light transmittance changes according to the irradiation amount of the laser beam. The reflection film 13 is a thin film layer for reflecting a reproduction laser beam that has passed through the substrate 11 and the recording layer 12 when reproducing the recording data recorded on the optical recording medium 1, and is made of gold, silver, or the like. It is formed on the recording layer 12 by, for example, sputtering using the above metal as a main raw material. The protective layer 14 is a layer that protects the reflective film 13 and the recording layer 12, and is formed so as to cover the outer surface of the reflective film 13.

Next, the recording principle of the optical recording medium 1 will be described with reference to the drawings.

In the optical recording medium 1, as shown in FIG. 1, virtual recording cells S 1, S ′ ′ obtained by virtually dividing the group 11 a along the rotation direction (circumferential direction) are defined as recording units. ing. Here, as shown in FIG. 2, the length of the virtual recording cell S in the direction along the group 11a is defined to be shorter than the focused beam diameter (diameter of the beam waist) D.

In this case, the recording laser beam emitted from the pickup of the recording device is irradiated. By controlling the irradiation time (that is, the irradiation amount of the laser beam) in multiple steps according to the value of the recording data, the degree of decomposition and alteration of the recording layer 12 (mainly organic dye) differs as shown in Fig. 2. Recording marks M a to M g (hereinafter, also referred to as “recording marks M” when not distinguished) are formed in the virtual recording cell S. In the figure, the degree of decomposition and deterioration is conceptually shown by the size of the recording mark M. In addition, when recording data is recorded with a recording laser beam, the recording mark M has a length corresponding to the irradiation time because the recording laser beam is irradiated while rotating the optical recording medium 1. It becomes an oval.

When multi-level recording is performed on the optical recording medium 1, the light reflectance when the virtual recording cell S is irradiated with the reproduction laser beam is, for example, 7 steps (8 steps including the unrecorded part). In this way, the degree of degradation and deterioration (the amount of change in light transmittance) of each of the recording marks M a to M g is specified. In this case, the light reflectance increases as the degree of degradation of the recording layer 12 decreases. For this reason, the virtual recording cell S on which the recording mark M is not recorded has the characteristic of maximum light reflectance, and the virtual recording cell S of the smallest recording mark M a has the largest light reflectance of the recording mark M. Thereafter, the light reflectance of each virtual recording cell S decreases in the order of the recording marks Mb to Mf, and the virtual recording cell S of the largest recording mark Mg has the minimum light reflectance. It has the following characteristics. Therefore, by controlling the irradiation amount of one laser beam and appropriately setting the area ratio of the degraded and degraded portion (that is, the light transmittance of the recording layer 12), the recording marks Ma to M having the seven levels of light reflectivity are obtained. g can be formed.

Next, characteristics of the organic dye used in the recording layer 12 of the optical recording medium 1 will be described with reference to the drawings.

Generally, the organic dye used in the recording layer 12 has a characteristic that the degree of decomposition and alteration increases as the irradiation time (irradiation amount) of the recording laser beam increases. On the other hand, the change in the light reflectance at this time is not linear with respect to the irradiation time (irradiation amount) of the recording laser beam. The recording laser beam irradiation time (irradiation amount) ), The degree of degradation is moderate for a while from the start of irradiation, becomes steep and linear after a predetermined time, and then gradually decreases again, exceeding a certain irradiation time. Later, it shows the characteristic that the degree hardly increases. The light transmittance of the organic dye that has not yet been degraded and altered, and the light transmittance of the organic dye that has been degraded and altered the most (organic dye that has been degraded and altered until the degree of degradation and degradation hardly increases) Also, the amount of change in light transmittance according to the degree of degradation and degradation varies depending on the material of the organic dye used. Therefore, for example, when five types of optical recording media 1 in which the recording layers 12 are formed of mutually different organic dyes are produced, the absolute light reflectances of the recording layers 12 of the optical recording media 1 are different from each other. . In this case, the absolute light reflectance is replaced by the reference light reflectance (100%) for the disk with a thin surface made of gold or the like applied to the smooth surface by, for example, sputtering. Means the light reflectance at the unrecorded portion (unrecorded virtual recording cell S) in the recording layer 12 of each optical recording medium 1 compared to the reference light reflectance. The characteristics of the relative light reflectivity of each recording layer 12 of each optical recording medium 1 are also different from each other as shown by characteristics C1 to C5 in FIG. In addition, as shown in the figure, the degree of the above-mentioned degradation alteration contributes to the slope of the curves of the characteristics C1 to C5. In this case, the relative light reflectance is obtained by replacing the value of the absolute light reflectance of the unrecorded portion (that is, the unrecorded virtual recording cell S) in the recording layer 12 of each optical recording medium 1 with 100%. Means the ratio of the light reflectance according to the irradiation time in the recording portion (that is, the recorded virtual recording cell S). Further, due to the difference in the absolute light reflectance and the relative light reflectance for each organic dye, the modulation degree, dynamic range, jitter characteristics, and B.E.R. Various characteristics such as rate) are also different. Furthermore, these various properties are determined not only by the material of the organic dye, but also by various parameters such as the coating thickness of the organic dye, the structure of the group 11a (depth, width or shape of the groove) and the material of the reflective film 13. It will be different depending on the situation.

In this case, the multi-recording is performed only when the optical reflectance of the optical Since the recording of a bell is possible, the absolute light reflectance of the recording portion having the highest light reflectance (the unrecorded virtual recording cell S) is somewhat large (for example, 40% to 80%), and Unless the difference in light reflectance between the recording part having the largest light reflectance and the recording part having the smallest light (the virtual recording cell S in which the recording mark M g is formed) is large to some extent, the recording data recorded at multi-levels will be obtained. Reproduction becomes difficult. The absolute light reflectivity is preferably as large as possible. However, in general, for example, the laser beam for reproduction is irregularly reflected in accordance with the characteristics of the above-described parameters and the structure of the group 11a, so that it is difficult for the pickup of the reproduction apparatus to pick up. It is difficult to secure values above 80% due to the reduced amount of return. Also, the value of the light reflectivity in the recorded portion (unrecorded virtual recording cell S) that has not been degraded and altered is replaced with 100%, and the degree of degradation and degeneration is the highest, and the recorded portion (degradation and degradation is degraded). When the ratio of the light reflectance of the virtual recording cell S) which has been decomposed and deteriorated until the laser state hardly increases is defined as the relative light reflectance dynamic, the relative light reflectance is determined from the characteristics of the organic dye described above. In the unrecorded area (approximately two-tenths of an area) of the dynamic range, and in the recorded part (the area of about two-tenths) where the degree of decomposition and degradation is the highest, the laser beam The relative light reflectance changes nonlinearly with respect to the irradiation time (irradiation amount), and the relative light reflection with respect to the irradiation time is in an area of about 6/10 which is an intermediate area between the two areas. The rate changes linearly. For this reason, for the optical recording medium 1, for example, the recording portion having the highest absolute light reflectance is in the range of 40% to 80%, and the recording portion having the highest light reflectance is within the range of 40% to 80%. The difference in light reflectance between the virtual recording cell S where the recording mark M a is recorded and the virtual recording cell S where the recording mark M g is recorded exceeds 40 points. preferable. Therefore, when selecting an organic dye to be used as the recording layer 12 or when inspecting non-defective products during the production of the optical recording medium 1, the difference between the absolute light reflectance and the light reflectance is determined by the above-described criteria. Value) is important. It should be noted that the two regions of about two-tenths in the unrecorded portion side and the recorded portion side described above, and the intermediate region The ratio of the area in the range of about 6/10 is largely determined by the organic dye used for the recording layer 12 and is not determined uniquely.

Next, a method for evaluating the optical recording medium 1 will be described with reference to the drawings. The optical recording medium 1 can be evaluated using any of the various characteristics described above, and is usually evaluated using a multilevel recording / reproduction evaluation apparatus. On the other hand, the inventor has determined that the characteristic data of the optical recording medium 1 measured by the multi-level recording / reproducing evaluation device is different from the characteristic data of the optical recording medium 1 measured by the binary recording / reproducing evaluation device. Have found that a certain correlation exists. For example, as described above, when the absolute light reflectivity and the relative light reflectivity dynamic range of the optical recording medium 1 recorded by the binary recording method satisfy predetermined criteria, regardless of the type of the above-described parameter, When recording on the optical recording medium 1 by the multi-level recording method, the absolute light reflectance is in the range of 40% to 80%, and the light reflectance between the unrecorded portion and the recording mark Mg is It has been found that the difference exceeds 40 points and is sufficient to identify each recording mark M a -M g. As another example, the C / N ratio of a reproduced signal to a binary recording signal (so-called 3T signal (692 ηs signal)) determined according to the orange hook (Compact Disc Recordable System Description) is used. When the C / N ratio measurement exceeds a predetermined level (for example, 50 dB), it is also found that the optical recording medium 1 can be used for multilevel recording. Furthermore, between the above-mentioned various characteristics of the optical recording medium 1 based on the binary recording method, such as the optical reflectance, modulation degree, dynamic range, jitter characteristics, and B.E.R. (bit error rate). Also find that a certain correlation exists.

Accordingly, hereinafter, as an example of the correlation found by the inventor, the absolute light reflectance and relative light reflectance dynamic range of the optical recording medium 1 recorded by the binary recording / reproducing method, and the multi-level recording Correlation between the absolute light reflectivity of the optical recording medium 1 recorded by the reproducing method and the difference in the light reflectivity described above. And a method for evaluating the optical recording medium 1 based on raw data on the absolute light reflectance and relative light reflectance dynamic range of the optical recording medium 1 recorded by the binary recording / reproducing method. explain. Note that, as the above-mentioned predetermined reference (threshold), the following description is based on the assumption that the lower limit of the absolute light reflectance is 40% and the lower limit of the relative light reflectance dynamic range is 40%. . In addition, the present invention evaluates the optical recording medium 1 (hereinafter, also referred to as “sample”) when selecting an organic dye to be used as the recording layer 12, and evaluates the optical recording medium 1 for each production lot during the production of the optical recording medium 1. This method can be applied to both evaluation of actual products at the time of quality inspection. The following describes an example of evaluation of a sample when selecting an organic dye.

First, a binary recording / reproducing evaluation apparatus for measuring the light reflectance of the optical recording medium 1 will be described with reference to FIG. The binary recording / reproduction evaluation device 40 is a general-purpose evaluation device, and has a function of a normal CD-R recorder and a function of measuring light reflectance. Specifically, the binary recording / reproducing evaluation device 40 includes a spindle servo 41, a spinneret motor 42, a pickup 43, a focus tracking servo 44, a feed servo 55, and a control device 46. In this case, the spindle motor 42 is driven and controlled by the spindle servo 41, and rotates the optical recording medium 1 at a constant linear velocity. The laser 43 (both not shown) is driven by a laser driver under the control of the controller 46 to irradiate the optical recording medium 1 with a recording laser beam or a reproducing laser beam. As a result, the recording of binary data on the recording layer 12 or the reproduction according to the level of the reproduction laser beam reflected by the optical recording medium 1 is performed.

The pickup 43 has an objective lens and a half mirror (both not shown), and focuses a recording or reproducing laser beam on the recording layer 12 of the optical recording medium 1. Specifically, focus tracking control of the objective lens is performed by the focus tracking servo 44, whereby a recording or reproducing laser beam is focused on the recording layer 12 of the optical recording medium 1. This pickup ⁴ 3 The optical recording medium 1 is reciprocated by a feeder 45 between the inner peripheral side and the outer peripheral side along the diameter direction of the optical recording medium 1. The control device 46 controls the drive of the spindle servo 41, the pickup 43, the focus tracking servo 44, and the feed servo 45, and the recording layer 1 based on the electric signal output from the pickup 43. The recorded data recorded in 2 is read, and the light reflectance of the reproducing laser beam reflected by the optical recording medium 1 is measured. Since the reading process of the recorded data and the measuring process of the light reflectance are known, their description is omitted.

First, samples 1 to 3 (not shown) are prepared by applying different organic dyes, respectively. Next, the medium evaluation processing 30 shown in FIG. In the medium evaluation process 30, first, predetermined data is recorded on the sample to be evaluated by the binary recording / reproducing evaluation device 40 (step 31). In this case, the recording laser beam emitted by the binary recording / reproduction evaluation device 40 is set to a relatively large power for binary recording. Therefore, since the recording layer 12 is greatly decomposed and deteriorated, the relative light reflectance of the recording portion in each sample is represented by the points P 1 to P 3 on the characteristics C 1 to C 3 of the samples 1 to 3 shown in FIG. As shown by 3, it drops significantly. Next, the absolute light reflectance of the unrecorded portion of each of the samples 1 to 3 and the relative light reflectance of the unrecorded portion and the recorded portion are measured by the binary recording / reproducing evaluation device 40 (step 32). Specifically, the binary recording / reproduction evaluation device 40 irradiates a reproduction laser beam toward each sample and simultaneously passes the reproduction laser beam reflected by the reflection film 13 after passing through the recording layer 12. Receive light. Next, after converting the reproduction laser beam received via the pickup 43 into an electric signal, the controller 46 controls the absolute light reflection of each sample 1 to 3 based on the level of the electric signal. Find the rate. Next, the control device

In step 46, the relative light reflectance of the recording portion is obtained for each of the samples 1 to 3 by replacing the value of the absolute light reflectance for each of the samples 1 to 3 with the light reflectance of 100%.

In this case, the absolute light reflectance of each of the unrecorded portions of Samples 1, 2, and 3 was 60%,

Measured at 50% and 30%, and the relative light reflections on the recorded portions of Samples 1, 2, and 3 It is assumed that the emissivity is measured as 10%, 65%, and 15%, respectively, as indicated by points P1 to P3 on characteristics C1 to C3 shown in FIG. Note that the characteristics C1 to C3 in the figure are based on the relative light reflectance of the recording portions of Samples 1, 2, and 3, and the relative light reflectance corresponding to the recording portion corresponding to each irradiation time was estimated. The characteristics are illustrated.

Next, the controller 46 obtains a relative light reflectance dynamic range of each of the samples 1 to 3 based on the relative light reflectance of each of the unrecorded portion and the recorded portion (step 33). In this case, as shown in FIG. 4, for example, the relative light reflectivity dynamic range Ra1 of sample 1 is 90%, the relative light reflectivity dynamic range Ra2 of sample 2 is 35%, and sample 3 is A relative light reflectivity dynamic range Ra3 of 85% is obtained. Next, the controller 46 compares the obtained absolute light reflectance with the corresponding lower limit (40% as a predetermined reference value), and determines whether each absolute light reflectance exceeds the lower limit. In addition to determining whether or not the relative light reflectance dynamic range of each sample 1 to 3 is compared with the corresponding lower limit (40% as a predetermined reference value), the relative light reflectance dynamic range is determined. To determine whether or not exceeds the lower limit (Step 3 4) ₀

As a result, the controller 46 determines that the sample 1 in which both the absolute light reflectance and the relative light reflectance dynamic range exceed the lower limit value is a non-defective product (step 35), and sets the sample in which the absolute light reflectance is lower than the lower limit value. 3 is determined to be defective, and sample 2 having a relative light reflectance dynamic range below the lower limit is determined to be defective (step 36). In this case, for sample 1 with a relative light reflectivity dynamic range of 90%, the region where the relative light reflectivity is linear has 54% of the relative light reflectivity dynamic range (90% x 6/10). Therefore, for example, in the case of seven-level multi-level recording, it is possible to secure a sufficiently large margin (relative light reflectance difference) between each step. On the other hand, in each of the samples 2 and 3, it is difficult to secure a sufficiently large margin between each step in multi-level recording of seven steps. Therefore, the organic dye used in Sample 1 It is determined that the recording medium 1 is suitable for use in the recording layer 12.

As described above, according to the method of measuring and evaluating the characteristic data of the multilevel optical recording medium, the absolute light reflectance of the unrecorded portion and the relative light By measuring the reflectivity dynamic range as characteristic data and evaluating the quality of the sample based on each measured characteristic data, the quality can be determined reliably and easily without using a dedicated multi-level recording / reproduction evaluation device. Can be evaluated. As a result, the characteristic data of the sample can be measured using the existing binary recording / reproduction evaluation device 40, and the evaluation can be performed based on the raw data.ぴ Evaluation cost and, consequently, manufacturing cost of optical recording medium 1 can be sufficiently reduced '. In addition, the reliability of the evaluation is further enhanced by performing the evaluation based on the absolute light reflectance and the relative light reflectance dynamic range that directly affect the quality of the optical recording medium 1 during the actual reproduction of the recorded data. Can be Further, as described above, the quality of the optical recording medium 1 can be evaluated by simply comparing the lower limit (reference characteristic data) with the characteristic data measured by the binary recording / reproducing evaluation device 40. The quality of the recording medium 1 can be evaluated.

It should be noted that the present invention is not limited to the above-described embodiment of the invention, and can be appropriately modified. For example, in the embodiment of the present invention, an example of evaluating the optical recording medium 1 employing an organic dye as the recording layer 12 has been described, but the multi-level optical recording medium according to the present invention has been described. The method of measuring the characteristic data and the method of evaluating the multi-level optical recording medium are not limited to the above, and the multi-level optical recording medium using an organic dye or an inorganic material other than those described above for the recording layer 12 may be used. It can also be applied to multi-level optical recording media for multi-level recording by phase change or magneto-optical. Furthermore, in the embodiment of the present invention, an example is shown in which the optical recording medium 1 is configured as a CD-R type optical recording medium. However, the present invention is not limited to this, and other optical recording media may be used. It is generally applied to recording media, and is not limited to disk-shaped rotating bodies. Absent. Further, in the embodiment of the present invention, the optical recording medium 1 is configured to irradiate the recording and reproducing laser beams from the substrate 11 side, but the reflective layer, the recording layer, and the protective layer are sequentially formed on the substrate. The present invention can also be applied to an optical recording medium which is stacked and configured to irradiate a recording and reproducing laser beam from the protective layer side.

Further, the characteristic data (data on light reflectance) shown in the embodiment of the present invention is an example, and can be applied to measurement of other characteristic data and an evaluation method based on the measured characteristic data. . Further, the numerical values of each light reflectance shown as an example are illustrative values for facilitating the understanding of the present invention, and can be appropriately changed. Further, the multi-level optical recording medium of the present invention includes various multi-level optical recording media that can perform multi-level multi-level recording as long as there are five or more levels. In addition, in the evaluation method described in the embodiment of the present invention, the lower limit (reference characteristic data) for the characteristic data measured by the binary recording / reproducing evaluation device 40 is obtained in advance based on the correlation. Although an example in which the quality of the optical recording medium 1 is evaluated by comparing the measured characteristic data with the lower limit has been described, the present invention is not limited to this. For example, based on the correlation, the characteristic data measured by the binary recording / reproduction evaluation device 40 is replaced with the characteristic data measured by the multi-level recording / reproduction evaluation device, and the replaced characteristic data and the multi-level recording It is also possible to evaluate by comparing with reference characteristic data for a reproduction evaluation device. Industrial applicability

As described above, according to the measuring method of Patent ¹ raw data for the multi-level optical recording medium according to the present invention, to measure the characteristic data of the multi-level optical recording medium using an existing binary recording reproducing evaluation apparatus This makes it possible to measure characteristic data of a multi-level optical recording medium without newly purchasing or manufacturing a dedicated multi-level recording / reproducing evaluation device, thereby reducing the measurement cost. This makes it possible to sufficiently reduce the manufacturing cost of the multi-level optical recording medium. A method for measuring special raw data for a multilevel optical recording medium is realized.

According to the method for evaluating a multilevel optical recording medium according to the present invention, the multilevel optical recording medium is evaluated by evaluating the multilevel optical recording medium based on characteristic data measured using an existing binary recording / reproduction evaluation apparatus. Since the multi-level optical recording medium can be evaluated without newly purchasing or manufacturing the multi-level recording / reproducing evaluation device, the evaluation cost can be reduced. Therefore, an evaluation method for a multi-level optical recording medium that can sufficiently reduce the manufacturing cost of the multi-level optical recording medium is realized.

Claims

Scope of word blue

1. A measuring method for measuring characteristic data of a multi-level optical recording medium manufactured to enable multi-level recording,

A method for measuring characteristic data of a multi-level optical recording medium, comprising measuring characteristic data of the multi-level optical recording medium using a binary recording / reproduction evaluation apparatus.

2. Predetermined data is recorded on the multi-level optical recording medium by the binary recording / reproducing evaluation device, and the characteristic data on the unrecorded part and the recorded part of the recorded multi-level optical recording medium is recorded. The method for measuring characteristic data of a multilevel optical recording medium according to claim 1, wherein the measurement is performed.

3. The multi-level optical recording medium is capable of multi-level recording by switching at least one of the irradiation time and the irradiation power of the recording laser beam so that the light reflectivity to the reproduction laser beam is controlled in multiple stages. The method for measuring characteristic data of a multi-level optical recording medium according to claim 1, wherein the characteristic data is manufactured.

4. In the multi-level optical recording medium, by switching at least one of the irradiation time and the irradiation power of the recording laser beam, the light reflectance with respect to the reproduction laser beam is controlled in multiple steps, thereby enabling multi-level recording. 3. The method for measuring characteristic data of a multi-level optical recording medium according to claim 2, wherein the characteristic data is manufactured.

5. The multi-level optical recording medium is characterized in that the reflectance of the reproduction laser beam is controlled in multiple stages by changing the transmittance of the recording layer by the recording laser beam. 4. The method for measuring characteristic data of a multilevel optical recording medium according to claim 3, wherein:

6. The multi-level optical recording medium is configured such that the transmittance of the recording layer is changed by the recording laser beam, 5. The method for measuring characteristic data of a multi-level optical recording medium according to claim 4, wherein the light reflectance is controlled in multiple stages.

7. The characteristic data of the multi-level optical recording medium according to claim 3, wherein the multi-level optical recording medium is configured so that the light reflectance with respect to the reproduction laser beam can be controlled in five or more steps. Measurement method.

8. The characteristic data of the multi-level optical recording medium according to claim 4, wherein the multi-level optical recording medium is configured such that the light reflectance with respect to the reproduction laser beam can be controlled in five or more steps. Measurement method.

9. The characteristic data of the multilevel optical recording medium according to claim 5, wherein the multi-level optical recording medium is configured so that the light reflectance with respect to the reproducing laser beam can be controlled in five or more steps. Measuring method.

10. The multi-level optical recording medium according to claim 6, wherein the multi-level optical recording medium is configured so that the light reflectance with respect to the reproduction laser beam can be controlled in five or more steps. How to measure characteristic data.

11. The multi-level optical recording medium based on the characteristic data measured by the characteristic data measuring method for the multi-level optical recording medium according to any one of claims 1 to 10. An evaluation method for a multi-level optical recording medium characterized by being evaluated.

12. Based on the measured characteristic data and the correlation previously obtained for both the characteristic data of the multi-level optical recording medium measured by the binary recording / reproduction evaluation device and the multi-level recording / reproduction evaluation device, respectively. 12. The evaluation method for a multi-level optical recording medium according to claim 11, wherein the quality of the multi-level optical recording medium is evaluated.

13. Evaluation of the quality of the multi-level optical recording medium by comparing reference characteristic data obtained in advance based on the correlation with the characteristic data measured by the binary recording / reproduction evaluation apparatus. The multi-level optical storage device according to claim 12, characterized in that: Evaluation method for recording media.