WO2004019327A1

WO2004019327A1 - Method for deciding recording condition of data onto optical recording medium and data recording device

Info

Publication number: WO2004019327A1
Application number: PCT/JP2003/010693
Authority: WO
Inventors: Syuji Tsukamoto; Narutoshi Fukuzawa
Original assignee: Tdk Corporation
Priority date: 2002-08-23
Filing date: 2003-08-25
Publication date: 2004-03-04
Also published as: JP2004086949A; AU2003261711A1; TW200405301A

Abstract

There is provided a data recording condition decision method capable of surely determining the data recording level difference when 2-bit data or more-bit data is recorded onto an optical recording medium and the data recorded on the recording medium is read and deciding the data recording condition so as to obtain a reproduction signal having a wide dynamic range. As the maximum light reflectance assigned for a virtual recording cell virtually set on the recording layer of the optical recording medium becomes higher, the recording power of the laser beam used for recording data is set at a higher level and as the minimum light reflectance assigned for the virtual recording cell becomes lower, the recording power of the laser beam used for recording data is set at a lower level.

Description

Description Method for determining data recording condition on optical recording medium and data recording device

The present invention relates to a method for determining conditions for recording data on an optical recording medium and a data recording apparatus. More specifically, the present invention relates to a method for recording two or more bits of data on an optical recording medium and recording the data on an optical recording medium. When reading the read data, it is necessary to determine the data recording conditions so that the difference in the recording level of the data can be reliably determined and a reproduced signal having a wide dynamic range can be obtained. A method for determining data recording conditions that can be performed and the ability to record data of 2 bits or more on an optical recording medium and to reliably determine the difference in the data recording level when reading data recorded on the optical recording medium Data recording conditions are determined so that a reproduced signal having a wide dynamic range can be obtained, and data can be recorded on an optical recording medium. The recording device. It relates. Conventional technology

Conventionally, optical recording media such as CDs and DVDs have been widely used as recording media for recording digital data, and the data recording method is to record data to be recorded along a track along a track. A method of modulating the length is widely used.

When such a recording method is used, when recording data, a laser beam whose intensity is modulated is irradiated along a track of the optical recording medium, and a pit having a predetermined length is formed. On the other hand, when reproducing data, a laser beam set to the reproducing power is irradiated along the track of the optical recording medium, and the presence or absence and length of the pit are detected.

In recent years, in response to the demand for high-density recording of data, tracks on optical recording media are virtually divided into virtual recording cells having a predetermined length, and virtual recording is performed. A so-called “multi-level recording method” has been proposed in which one of 2 ^N types (N is an integer of 2 or more) of different recording marks is formed in a recording cell to record N-bit data. .

In the multilevel recording method, the total energy of the laser beam irradiated to the virtual recording cell, that is, (power of the laser beam) X (time of irradiation of the virtual recording cell with the laser beam) is changed in ^2N steps. Thus, ^2N types of recording marks are formed in a virtual recording cell, and N bits of data are recorded. As a result, the virtual recording cell in which the total energy of the irradiated laser beam is different and different recording marks are formed will have different light reflectivity with respect to the laser beam. Data can be reproduced by irradiating along the track of the optical recording medium and detecting the amount of laser beam reflected by the virtual recording cell. In this way, by changing the optical reflectance of the virtual recording cell to ^2N steps, N-bit data is recorded on the optical recording medium, and the data is recorded on the optical recording medium with high density. In order to increase the difference in light reflectance between the virtual recording cell with the highest light reflectance and the virtual recording cell with the lowest light reflectance, that is, to increase the dynamic range, It is necessary to control the total energy of the laser beam applied to the recording cell, and in order to satisfy such a requirement, an optical recording medium configured to record data by a multi-level recording method is used. For example, a recording layer containing an organic dye material is provided.

The light reflectance of the recording layer containing the organic dye material is such that, when no data is recorded, when the laser beam having the maximum power or more is irradiated, the organic dye material is decomposed and deteriorated. It has the property of reducing light reflectance. Therefore, by changing the total energy of the laser beam applied to the virtual recording cell in ^2N steps, the light reflectance of the virtual recording cell in which the recording mark is formed can be changed in ^2N steps, It becomes possible to record N-bit data with different recording levels on a recording medium. However, when forming a recording mark on a recording layer containing an organic dye material, the relationship between the total energy of the laser beam applied to the virtual recording cell and the light reflectance of the virtual recording cell is not linear, and When the total energy of the laser beam applied to the recording cell is less than the first predetermined value, even if the total energy of the laser beam applied to the virtual recording cell changes, the light reflectance of the virtual recording cell changes. When the total energy of the laser beam applied to the virtual recording cell is greater than or equal to the second predetermined value, the light reflectance of the virtual recording cell is saturated, and the laser beam applied to the virtual recording cell is saturated. It has been observed that even if the total energy of the system changes, the light reflectivity of the virtual recording cell hardly changes.

Conventionally, however, the laser beam applied to the virtual recording cell is within a range in which the relationship between the total energy of the laser beam applied to the virtual recording cell and the light reflectance of the virtual recording cell becomes almost linear. By changing the total energy of the beam, recording marks with different recording levels were formed in the virtual recording cells.

However, in order to obtain a reproduced signal with a wide dynamic range, the difference in light reflectance between the virtual recording cell with the highest light reflectance and the virtual recording cell with the lowest light reflectance is as large as possible. As described above, it is necessary to control the total energy of the laser beam applied to the virtual recording cell, and the energy is applied to the virtual recording cell within a range in which the relationship with the light reflectance of the virtual recording cell becomes almost linear. When recording marks with different recording levels are formed in virtual recording cells by changing the total energy of the laser beam to be reproduced, there is a problem that a reproduced signal having a sufficiently wide dynamic range cannot be obtained. Was. Disclosure of the invention

Therefore, according to the present invention, when data of 2 bits or more is recorded on an optical recording medium, and when the data recorded on the optical recording medium is read, a difference in data recording level can be reliably determined, Determine the data recording conditions so that a playback signal with a wide dynamic range can be obtained. It is intended to provide a method for determining data recording conditions that can be specified. .

Another object of the present invention is to record data of 2 bits or more on an optical recording medium and, when reading the data recorded on the optical recording medium, to reliably determine the difference in the data recording level. An object of the present invention is to provide a data recording device capable of determining data recording conditions and recording data on an optical recording medium so that a reproduced signal having a wide dynamic range can be obtained.

The present inventor has conducted intensive studies to achieve the object of the present invention, and as a result, when the recording power level of the laser beam changes, the irradiation time of the laser beam set to the recording power to the virtual recording cell and The relationship between the virtual recording cell and the light reflectance changes, and the higher the recording power of the laser beam, the higher the level of the laser beam set to the recording power, even if a higher maximum reflectance is assigned to the virtual recording cell. The data at different recording levels can be recorded in the virtual recording cell without greatly changing the irradiation time of the laser beam, while the lower the recording power level of the laser beam, the lower the minimum reflectance in the virtual recording cell Assigns different recording levels to the virtual recording cells without significantly changing the irradiation time of the laser beam set to the recording power. Found that it is possible to record.

The present invention is based on such findings, and according to the present invention, the object of the present invention is to provide a plurality of virtual recording cells, which are virtually set in a recording layer of an optical recording medium, with two or more bits. When recording the data, the recording power of a laser beam used for recording data is set according to the maximum light reflectance and / or the minimum light reflectance allocated to the virtual recording cell. in a preferred embodiment of the recording condition _c present invention is achieved by the determination method, the higher the virtual split the recording cell skilled Teru maximum reflectivity is high, the recording power of the laser beam is set to a high level.

In another preferred embodiment of the present invention, the virtual recording cell As the minimum reflectance to be applied is lower, the recording power of the laser beam is set to a lower level.

In a further preferred aspect of the present invention, as the maximum relative reflectance assigned to the virtual recording cell is higher, the recording power of the laser beam is set to a higher level, and the maximum relative light reflectance RRaH and the minimum relative light The reflectance RR hH is set to satisfy 100—RR aH and RR hH.

In another preferred embodiment of the present invention, as the minimum reflectance assigned to the virtual recording cell is lower, the recording power of the laser beam is set to a lower level, and the maximum relative light reflectance RRaH and the minimum The relative light reflectance RRhH is set so as to satisfy 100_RRaL> RRhL.

In a preferred embodiment of the present invention, the recording layer of the optical recording medium contains an organic dye material.

The object of the present invention is also to provide a maximum light allocated to the virtual recording cell when recording data of 2 bits or more in a plurality of virtual recording cells virtually set on the recording layer of the optical recording medium. Achieved by a data recording device characterized by storing recording condition setting data in which a recording beam of a laser beam used for recording data is set according to the reflectance and / or the minimum light reflectance. Is done.

In a preferred embodiment of the present invention, as the maximum reflectance assigned to the virtual recording cell is higher, the recording level of the laser beam is set to a higher level, and the recording condition setting data is generated. I have. In another preferred embodiment of the present invention, as the maximum reflectance assigned to the virtual recording cell is lower, the recording power of the laser beam is set to a lower level, and the recording condition setting data is generated. ing. In a further preferred aspect of the present invention, as the maximum relative reflectance assigned to the virtual recording cell is higher, the recording power of the laser beam is set to a higher level, and the maximum relative light reflectance RRaH and the minimum relative light Set so that the reflectance RR hH satisfies 1 0 0— RR a H and RR h H Then, the recording condition setting data is generated.

In another preferred embodiment of the present invention, the lower the minimum reflectance assigned to the virtual recording cell, the lower the recording power of the laser beam is set to a lower level, and the maximum relative light reflectance RR aH The minimum relative light reflectance RRhH is set so as to satisfy 100—RRaL> RRhL, and the recording condition setting data is generated.

The above and other objects and features of the present invention will be apparent from the following description and corresponding drawings. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic perspective view of an optical recording medium according to a preferred embodiment of the present invention.

FIG. 2 is an enlarged schematic cross-sectional view of a portion surrounded by a circle of the optical recording medium shown in FIG.

FIG. 3 is a diagram showing a state in which recording marks are formed in a plurality of virtual recording cells.

FIG. 4 is a graph showing the relationship between the time during which a recording layer of an optical recording medium is irradiated with a laser beam whose power is set to the recording power, and the light reflectance of the recording layer.

FIG. 5 shows the change in the power of the laser beam applied to the virtual recording cell S. FIG. 6 shows the recording power set when the recording power of the laser beam applied to the recording layer of the optical recording medium is changed. 4 is a graph showing the relationship between the time of laser beam irradiation and the light reflectance of the recording layer.

FIG. 7 is a block diagram of a data recording device according to a preferred embodiment of the present invention.

FIG. 8 is a graph showing the result of measuring the relationship between the light reflectance of each virtual recording cell and the irradiation time of the laser beam set to the recording power in Example 1.

FIG. 9 shows the recording power P w of the laser beam in the second embodiment, 9 is a graph showing the result of measuring the relationship between error rates. DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a partially cut-away schematic perspective view of an optical recording medium, and FIG. 2 is a substantially enlarged perspective view of a circled portion in FIG.

As shown in FIGS. 1 and 2, the optical recording medium 1 according to the present embodiment is configured as a write-once DVD-R type optical recording medium, and includes a light-transmitting substrate 11 and a dummy substrate. 1 2 and a recording layer 21, a reflective layer 22, a protective layer 23 and a bonding layer 24 between the light-transmitting substrate 11 and the dummy substrate 1 2 .

As shown in FIG. 1, the light-transmitting substrate 11 is formed in a disk shape using a light-transmitting resin.

In FIG. 2, the lower surface of the light-transmitting substrate 11 constitutes a light incident surface on which a laser beam is incident. As shown in FIG. 2, the upper surface of the light-transmitting substrate 11 has a central portion. A group 11a and a land 11b for guiding the laser beam are spirally formed from the vicinity toward the outer edge.

As shown in FIG. 2, the recording layer 21 is formed so as to cover the group 11 a and the land 11 b formed on the upper surface of the light transmitting substrate 11, and comprises a cyanine, merocyanine, and methine-based material. It contains organic dyes such as dyes and derivatives thereof, benzene thiol metal complexes, phthalocyanine dyes, naphtha thiocyanine dyes, and azo dyes.

When the recording layer 21 is irradiated with a laser beam having a power equal to or higher than a predetermined value, the organic dye contained in the recording layer 21 is decomposed and deteriorates, and the light reflectance of the portion irradiated with the laser beam is changed. Changes.

The reflective layer 22 reflects the laser beam applied to the recording layer 21 via the light-transmitting substrate 11 when reproducing data recorded on the recording layer 21 of the optical recording medium 1. This is a thin film layer for It is formed by the sputtering method used as a part.

As shown in FIG. 2, a protective layer 23 is formed so as to cover the surface of the reflective layer 22 in order to protect the reflective layer 22 and the recording layer 21.

As shown in FIG. 2, an adhesive layer 24 is formed on the protective layer 23. The adhesive layer 24 allows the light-transmitting substrate 11, the recording layer 21, the reflective layer 22 and the protective layer 24 to be formed. The laminate composed of the layers 23 and the dummy substrate 12 are adhered.

In this embodiment, each of the light-transmitting substrate 11 and the dummy substrate 12 has a thickness of about 0.6 mm.

In the present embodiment, 3-bit data is recorded on the recording layer 21 of the optical recording medium 1.

As shown in FIGS. 1 and 2, the recording layer 21 of the optical recording medium 1 includes a plurality of virtual recording cells S, S having a predetermined length virtually along the group 11a. Each virtual recording cell S constitutes a recording unit for recording data.

As shown in FIG. 3, the virtual recording cells S, S,... Have a length L in the direction along the group 11a of each virtual recording cell S smaller than the spot diameter of the laser beam. As such, it is virtually set.

In FIG. 3, different recording marks M a, M b, M c, M d, M e, M f, M g, M are respectively stored in eight consecutive virtual recording cells S, S,. h is formed, and three bits of data are recorded at different recording levels, and each virtual recording cell S is irradiated with a laser beam whose power is set to a recording level. By controlling the length of time, the degree of degradation of the organic dye material in the virtual recording cell S can be controlled, and different recording marks can be formed in the virtual recording cell S.

Fig. 3 shows the degradation of the organic dye material in virtual recording cell S. The degree is indicated by the size of the recording marks Ma, Mb, Mc, Md, Me, Mi, Mg, and Mh.In recording data, the laser beam is applied to the recording layer while rotating the optical recording medium 1. to be irradiated to 2 1, each virtual recording cell S, oval recording marks Ma, Mb, Mc, Md, M e, M f, g N Mh is formed.

The organic dye material has such a property that the light reflectance becomes lower as the degree of decomposition and alteration is larger.Therefore, the virtual recording cell S in which no recording mark is formed and no data is recorded is the largest. The virtual recording cell S having a larger light reflection rate and a larger recording mark has a smaller light reflection rate.

FIG. 4 is a graph showing the relationship between the time of irradiating the recording layer 21 of the optical recording medium 1 with a laser beam whose power is set to the recording power and the light reflectance of the recording layer 21.

The degree of degradation of the organic dye material increases as the irradiation time of the laser beam set at the recording power increases, and as shown in Fig. 4, the laser beam set at the recording power changes. As the irradiation time increases, the light reflectance of the recording layer 21 decreases.

Therefore, the time for irradiating the laser beam set to the recording power is Ta, and the light reflectance Ra of the recording layer 21 at the shortest time is determined by the virtual recording cell S having the maximum light reflectance. In addition to allocating the light reflectance, the laser beam set at the recording power is irradiated with the laser beam for the time Th, and the light reflectance R h of the recording layer 21 when the laser light is the longest is assumed to be the virtual light having the minimum light reflectance. Assigned as the light reflectance of the recording cell S, the light reflectance between the maximum light reflectance R a and the minimum light reflectance R h is divided into seven, and the six types of mutually different light reflectance Rb, Rc, Rd, Re, Ri, and Rg are determined, assigned as the light reflectance of the virtual recording cells S having different data recording levels, and recorded by irradiating a laser beam. The organic dye material contained in the layer 21 is decomposed and deteriorated, and the light reflectance of the virtual recording cell S is changed to Ra, Rb, Rc, The irradiation time of the laser beam of the recording power required to obtain R d, Re, R f, R g, and R h is determined, respectively, and is temporarily determined according to the data recording level. By irradiating the virtual recording cell s with a laser beam set to the recording power to form a recording mark, it becomes possible to record 3-bit data in each virtual recording cell S. However, the maximum irradiation time T max of the laser beam to the virtual recording cell is equal to L / V (where L is the length of the virtual recording cell and V is the recording linear velocity). It is necessary to set the irradiation time T h of the laser beam for forming the recording mark M h having the light reflection rate R h of not more than T max. For example, when the length L of the virtual recording cell S is 385 nm and the recording linear velocity V is 7 m / sec, the irradiation time T h of the laser beam for forming the recording mark M h is It must be set to 55 nsec or less.

FIG. 5 is a diagram showing a modulation pattern of the power of the laser beam applied to the virtual recording cell S.

As shown in FIG. 5, the power of the laser beam applied to the virtual recording cell S is selectively modulated into the recording power w and the base power, and the recording mark M to be formed in the virtual recording cell S is obtained. a, M b, M c, M d, M e, M f, M g, and M h corresponding to the time T a, T b, T c, at which the power of the laser beam is set to the recording power w. Td, Te, Tf, Tg, and Th are set.

Immediately after the irradiation of the laser beam set to the recording power, the organic dye material contained in the recording layer 21 decomposes and decomposes little by little, starting from the start of the irradiation of the laser beam set to the recording power. After the elapse of the first predetermined time, the degree of decomposition and alteration of the organic dye material increases substantially linearly as the irradiation time of the laser beam increases, and after the elapse of the second predetermined time, the irradiation time of the laser beam Even if the recording layer 21 is increased, the degree of decomposition and deterioration of the organic dye material hardly increases. Therefore, as shown in FIG. 4, the light reflectance of the recording layer 21 depends on the recording power. When the set irradiation time of the laser beam is within the area A shorter than the first predetermined time, the laser beam irradiation time does not change much even if the irradiation time is increased, and the laser beam set at the recording power is not changed. When the irradiation time of the beam is within the area B for more than the first predetermined time and less than the second predetermined time, the laser beam As the irradiation time of the laser beam increases, it decreases almost linearly, and the irradiation time of the laser beam set to the recording power is longer than the second predetermined time.

When it is in C, even if the irradiation time of the laser beam increases, it does not change much and the light reflectance reaches Rs.

Therefore, when the light reflectance in the area A and the area C as well as the light reflectance in the area B are assigned as the light reflectance of the virtual recording cell S, the light reflectance in the area B becomes Using the light reflectance in the area A and the area C, data of different recording levels is stored in the virtual recording cell S, as compared with the case where data of different recording levels are recorded in the virtual recording cell S. When recording, it is necessary to greatly change the irradiation time of the laser beam set to the recording power. Conventionally, the light reflectance in the area B shown in FIG. S is assigned as the light reflectance of the virtual recording cell, and the irradiation time of the laser beam set to the recording power is controlled so that the light reflectance of the virtual recording cell S becomes the assigned value. Recording data with different recording levels It has been configured to.

However, as described above, the light reflectance in the area B shown in FIG. 4 is assigned as the light reflectance of the virtual recording cell S, and the light reflectance of the virtual recording cell S becomes the assigned value. As described above, when recording data of different recording levels in the virtual recording cell by controlling the irradiation time of the laser beam set to the recording power, the maximum reflectance Ra and the minimum reflectance Rh are calculated. There has been a problem that the difference cannot be made sufficiently large, and as a result, a reproduced signal having a sufficiently wide dynamic range cannot be obtained.

Therefore, the maximum light reflectance R of the virtual recording cell S can be maintained within a range where data of different recording levels can be recorded in the virtual recording cell S without greatly changing the irradiation time of the laser beam set in the recording power. a is as close as possible to the light reflectance R o of the virtual recording cell S where no recording mark is formed, and the minimum light reflectance R h of the virtual recording cell S is the saturation light reflectance R s The light reflectivity of each virtual recording cell S is assigned so that it is as close as possible, and the time for irradiating the laser beam set to the recording power w Determining the minimum and maximum values of is necessary to reproduce a signal with a wide dynamic range.

Therefore, the inventor of the present invention has conducted diligent research and has found that recording of a laser beam. When the first level changes, the relationship between the irradiation time of the laser beam set to the recording power w to the virtual recording cell S shown in FIG. 4 and the light reflectance of the virtual recording cell S changes. and, as the level of the recording Pawa P _w of the laser beam is high, the virtual record be assigned a higher maximum reflectance in the cell S, the recording power _P v this set laser beam without significantly changing the irradiation time of the recording Data with different levels can be recorded in the virtual recording cell S. On the other hand, as the level of the recording power _P of the laser beam is lower, even if a lower minimum reflectivity is assigned to the virtual recording cell S, the recording power is reduced. It has been found that data with different recording levels can be recorded in the virtual recording cell s without greatly changing the set irradiation time of the laser beam.

FIG. 6 shows the time of irradiating the laser beam set to the recording power / ³ w when the recording power w of the laser beam irradiating the recording layer 21 of the optical recording medium was changed, and the recording layer 2 6 is a graph showing the relationship between the light reflectance of Example 1 and the light reflectance.

As shown in FIG. 6, according to the study of the present inventors, when the recording power of the laser beam is set to a high level, the light reflectance of the recording layer 21 is changed to the laser beam set to the recording power w. In a short time after the start of irradiation of the laser beam, in other words, at a stage where the light reflectance is high, the light reflectance decreases almost linearly as the irradiation time of the laser beam increases, and At an early stage, in other words, at a stage where the light reflectance does not decrease so much, even if the irradiation time of the laser beam is increased, the light reflectance does not change much, and eventually the saturated light reflectance R s On the other hand, when the recording power of the laser beam is set to a low level, the light reflectance of the recording layer 21 starts to irradiate the laser beam at the set recording power. From a relatively long time Even if the laser beam irradiation time increases over time, it does not change much and the light reflectance is relatively low. At this stage, as the laser beam irradiation time increases, the light reflectivity power decreases almost linearly, and even if the laser beam irradiation time increases, the light reflectivity does not change much. It has been observed that the light reflectance does not change much even if the laser beam irradiation time increases, only after a long time is required and the light reflectance is considerably low.

Therefore, if the recording power w of the laser beam is set to a high level, the irradiation time of the laser beam set to the recording power can be maintained even if the maximum light reflectance assigned to the virtual recording cell S is set to a high value. Since it is possible to record data having different recording levels in the virtual recording cell S without greatly changing it, if the recording power w of the laser beam is w /, it is assigned to the virtual recording cell s. Can be assigned to the virtual recording cell S when the maximum light reflectivity R a H and the maximum relative light reflectivity RR a H (%) and the recording power of the laser beam are ^ (PwL <PwH). The maximum light reflectivity R a L and the maximum relative light reflectivity RR a L (%) satisfy the following equation.

R a L. <R a H

RR a L <RR a H

Here, the relative light reflectance RR i (%) when the absolute light reflectance is R i is defined by the following equation.

RR i (%) = {(R i-R s) / (R o — R s)} X 100 Thus, the maximum light reflectance Ra and the maximum relative light reflectance RR a allocated to the virtual recording cell S By setting the recording power level of the laser beam according to (%), the maximum light reflectance Ra and the maximum relative light reflectance RRa (%) assigned to the virtual recording cell S are set to high values. However, data with different recording levels can be recorded in the virtual recording cell S without greatly changing the irradiation time of the laser beam set to the recording power w, and a reproduced signal having a wide dynamic range can be reproduced. It is possible to obtain.

On the other hand, if the recording power w of the laser beam is set to a low level, even if the minimum light reflectance assigned to the virtual recording cell S is set to a low value, Since it is possible to record data of different recording levels in the virtual recording cell S without greatly changing the irradiation time of the laser beam set to the recording power, the recording power P w of the laser beam is In some cases, when the minimum light reflectance R hL and the minimum relative light reflectance RR h L (%) that can be assigned to the virtual recording cell S and the recording power of the laser beam are (PwL <PwH), The minimum light reflectance R hL and the minimum relative light reflectance RR h L (%) that can be assigned to the virtual recording cell S satisfy the following equations.

R h L <R h H

RRh L <RR hH

Thus, by setting the level of the recording power w of the laser beam according to the minimum light reflectance R h and the minimum relative light reflectance RR h (%) assigned to the virtual recording cell S, the virtual recording cell S Even if the minimum light reflectance R h and the minimum relative light reflectance RR h (%) are set to low values, the recording level can be maintained without significantly changing the irradiation time of the laser beam set to the recording power. Can be recorded in the virtual recording cell S, and a reproduced signal having a wide dynamic range can be obtained.

Further, as shown in FIG. 6, when the level of the recording power of the laser beam is high, the light reflectance of the recording layer 21 increases at a stage where the level of the light reflectance is relatively high and the irradiation time of the laser beam As the light reflection increases, the light reflection decreases almost linearly, while the light reflectance of the recording layer 21 increases with the irradiation time of the laser beam at a stage where the light reflection level is not so low. Even if the recording power P w of the laser beam is set to a high level P w / f in order to increase the maximum light reflectance assigned to the virtual recording cell S, the virtual recording cell will not change. The maximum relative light reflectance RR a H and the minimum relative light reflectance RR hH assigned to S are determined so as to satisfy the following equation.

1 00 -R R a H <R R h H

If the recording power of the laser beam is w /, the virtual recording cell S By determining the maximum relative light reflectance RR a H and the minimum relative light reflectance RR hH assigned to the laser beam in this manner, the recording power is set when the recording power of the laser beam is P wiJ. Even if the irradiation time of the laser beam is not significantly changed, the maximum relative light reflectance RR a H and the maximum relative light reflectivity of the virtual recording cell S can be recorded within the virtual recording cell S within a range where data with different recording levels can be recorded in the virtual recording cell S, respectively. It becomes possible to assign the minimum relative light reflectance RRhH.

On the other hand, when the level of the recording power _P w of the laser beam is low, as shown in FIG. 6, the light reflectivity of the recording layer 21 is maintained until the level of the light reflectivity becomes relatively low. As the irradiation time of the laser beam increases, it does not decrease almost linearly, while the light reflectance of the recording layer 21 increases until the level of the light reflectance becomes significantly lower. Since it is recognized that the irradiation time increases almost linearly, the recording power of the laser beam is set to a low level so as to increase the minimum light reflectance assigned to the virtual recording cell S. The maximum relative light reflectance RR a L and the minimum relative light reflectance RR h L assigned to the virtual recording cell S are determined so as to satisfy the following equation.

1 00 -RR a L> RR h L

When the recording power of the laser beam is, the maximum relative light reflectance RR a L and the minimum relative light reflectance RR h L assigned to the virtual recording cell S are determined in this manner, and the laser When the recording power of the beam is P, the data with different recording levels can be recorded in the virtual recording cell S without greatly changing the irradiation time of the laser beam set to the recording power. Thus, the maximum relative light reflectance RRaL and the minimum relative light reflectance RRhL of the virtual recording cell S can be assigned.

According to the above basic idea, according to the maximum light reflectance R a and the maximum relative light reflectance RR a and the minimum light reflectance R h and the minimum relative light reflectance RR h assigned to the virtual recording cell S. Thus, the recording power _P w of the laser beam used for recording data is selected, and other characteristics, For example, the optimum recording power w is determined from the recording power of the selected laser beam in accordance with the error rate when reproducing data.

Further, the light reflectance between the maximum light reflectance R a and the minimum light reflectance R h is roughly divided into seven equal parts, and six different light reflectances R b, R c, R d, R e, R f and R g are determined, and assigned as the light reflectance of the virtual recording cell S having different data recording levels, and the organic dye material contained in the recording layer 21 is decomposed and deteriorated by irradiating a laser beam. And the recording power _P w "of the laser beam required to set the light reflectance of the virtual recording cell S to be Ra, Rb, Rc, Rd, Re, Rf, Rg, and Rh. The optimum level and the irradiation time of the laser beam set to the optimum recording power are determined for each virtual recording cell S having a different data recording level, and the recording condition setting data is generated.

The recording condition setting data generated in this way is stored in the memory of the data recording device in association with ID data specifying the type of the optical recording medium 1, and is read out when recording data. The irradiation time of the laser beam set to the optimum recording power P w to be applied to the virtual recording cell S is determined according to the level of the laser beam recording power and the data recording level. The recording layer 21 is irradiated with a laser beam to record data.

As shown in FIG. 7, the data recording device 40 is configured as a so-called DVD-R recorder, and includes a spindle servo 41, a spindle motor 42, a pickup 43, a focus tracking servo 44, and a feed servo 4. 5 and a controller 4 6 are provided.

The spindle motor 42 is driven and controlled by a spindle servo 41 to rotate the optical recording medium 1 at a constant linear velocity.

The pickup 43 is controlled by the control device 46 to record data. At the time of recording, the optical recording medium 1 is irradiated with a laser beam having an amplitude from the base power P to the recording power, and at the time of reproducing data recorded on the optical recording medium 1, the reproducing power r is applied to the optical recording medium 1. It is configured to irradiate a laser beam set to.

Further, the pickup 43 has an objective lens (not shown) and a half mirror (not shown). When recording data or reproducing data, the laser beam is optically recorded by the objective lens and the half mirror. The light is focused on the recording layer 21 of the medium 1. Specifically, the objective lens is subjected to focus tracking control by the focus tracking servo 44, and the laser beam is focused on the recording layer 21 of the optical recording medium 1.

The pickup 43 is reciprocated by a servo 45 between the inner circumference and the outer circumference along the diameter direction of the optical recording medium 1, while the optical recording medium 1 is moved by a spindle motor 42. Since the laser beam is rotated at a constant linear velocity, the laser beam is applied to the entire surface of the recording layer 21 along the track.

The controller 46 controls the drive of the spindle servo 41, the pickup 43, the focus tracking servo 44 and the feed servo 45, and based on the electric signal output from the pickup 43. Thus, the data recorded on the recording layer 21 is read.

Although not shown, the memory of the control device 46 stores recording condition setting data in association with ID data for specifying the type of the optical recording medium 1.

When recording data on the recording layer 21 of the optical recording medium 1, first, the control device 46 reads the ID data recorded on the optical recording medium 1, and records the data in the memory according to the ID data. The corresponding recording condition setting data is read.

Next, the controller 46 is used to record data on the recording layer 21 of the optical recording medium 1 according to the read recording condition setting data. And it determines the recording power _{P w} of the laser beam, in accordance with the data of the recording level, and determines the irradiation time of the optimum recording power P This set laser beam is irradiated on a virtual recording cells S, the control device 4 By 6, the laser driver of the pickup 43 is controlled, and the irradiation time of the laser beam applied to the virtual recording cell S is controlled according to the recording level of the data to be recorded.

According to the present embodiment, the configuration is such that the higher the maximum light reflectance Ra and the maximum relative light reflectance RRa (%) assigned to the virtual recording cell S, the higher the recording power of the laser beam is set to a higher level. Therefore, even if the maximum light reflectance Ra and the maximum relative light reflectance RRa (%) assigned to the virtual recording cell S are set to high values, the recording power PH significantly changes the irradiation time of the set laser beam. Without recording, data having different recording levels can be recorded in the virtual recording cell S, and a reproduced signal having a wide dynamic range can be obtained.

Further, according to the present embodiment, the lower the minimum light reflectance R h and the minimum relative light reflectance RR h (%) assigned to the virtual recording cell S, the lower the recording power ^ P w of the laser beam. Even if the minimum light reflectance R h and the minimum relative light reflectance RR h (%) assigned to the virtual recording cell S are set to low values, the recording power is set to “w”. Thus, data having different recording levels can be recorded in the virtual recording cell S without greatly changing the irradiation time of the laser beam, and a reproduced signal having a wide dynamic range can be obtained.

Furthermore, according to the present embodiment, when the recording power w of the laser beam is set to a high level P in order to increase the maximum light reflectance assigned to the virtual recording cell S, The maximum relative light reflectivity RR a H and the minimum relative light reflectivity RR h H are determined so as to satisfy the following equation. Therefore, when the recording power of the laser beam is P wiJ, the recording power The maximum relative light reflectance of the virtual recording cell S is set within the range where data with different recording levels can be recorded in the virtual recording cell S without greatly changing the irradiation time of the laser beam set in the virtual recording cell S. It becomes possible to assign RR a H and minimum relative light reflectance RR h H.

1 0 0-R R a H <R R h H

According to the present embodiment, when the recording power of the laser beam is set to a low level P w in order to lower the minimum light reflection rate to be allocated to the virtual recording cell S, the virtual recording cell S is allocated to the virtual recording cell S. The maximum relative light reflectivity RR a L and the minimum relative light reflectivity RR h L are determined so as to satisfy the following equation.If the recording power of the laser beam is, then the recording power The maximum relative light reflectance RR a L of the virtual recording cell S, respectively, within the range where data with different recording levels can be recorded in the virtual recording cell S without greatly changing the laser beam irradiation time set in And the minimum relative light reflectance RR h L can be assigned.

Further, according to the present embodiment, the memory (not shown) of the control device 46 of the data recording device 50 stores the recording condition setting data in association with the ID data specifying the type of the optical recording medium 1. In recording the data on the recording layer 21 of the optical recording medium 1, the ID data recorded on the optical recording medium 1 is read by the controller 46, and the data is read according to the ID data. , corresponding recording condition setting data stored in the memory is read out, according to the recording condition setting data, together with the record power _{P w} of the laser beam is determined to an optimum level, the data of the recording level Accordingly, the configuration is such that the irradiation time of the laser beam set to the optimum recording power for irradiating the virtual recording cells S having different recording levels is determined accordingly. Thus, it is possible to record data having different recording levels in the recording area and obtain a reproduced signal having a wide dynamic range.

Hereinafter, in order to further clarify the effects of the present invention, examples and comparative examples will be described.

Example 1

An optical recording medium sample was produced as follows. First, by injection molding, the group and land have a thickness of 0.6 mm and a diameter of 12 O mm, and the surface and the track pitch (group pitch) are 0.74 m. A disk-shaped light-transmitting substrate made of the formed polycarbonate was prepared.

Next, the light-transmitting substrate is set in a spin coating apparatus, and while rotating the light-transmitting substrate, the azo-based material represented by the following structural formula is placed on the surface on which the groups and lands of the light-transmitting substrate are formed. An organic solvent containing an organic dye was added dropwise to form a coating film, and the coating film was dried to form a recording layer having a thickness of 100 nm on the group.

Further, the light-transmitting substrate on which the recording layer was formed was set in a sputtering apparatus, and a reflective layer made of an alloy of Ag, Pd, and Cu and having a thickness of 150 nm was formed on the recording layer. Was formed.

Next, it is set in a light-transmitting substrate spin coating apparatus, and while rotating the light-transmitting substrate, the acrylic UV-curable resin is dissolved in a solvent, and the prepared resin solution is applied to the surface of the reflective layer. To form a coating film, and the coating film was irradiated with ultraviolet rays to cure the acrylic ultraviolet curable resin, thereby forming a protective layer.

Further, while rotating the light-transmitting substrate, an ultraviolet-curable adhesive was dropped on the protective layer 23 to form an adhesive layer. Next, a dummy substrate made of polycarbonate and having a thickness of 0.6 mm and a diameter of 120 mm, which is made by injection molding, is adhered to the surface of the adhesive layer, and is irradiated with ultraviolet light to be cured by ultraviolet curing. The agent was cured to produce an optical recording medium sample.

The optical recording medium sample thus prepared was set on an optical recording medium evaluation device “DDU100” (trade name) manufactured by Pulstec Industrial Co., Ltd., and the recording linear velocity was set to 7.0 m / sec. The recording power of the laser beam was set to 9.0 OmW, and the laser beam was irradiated from the light-transmitting substrate side.

Here, along the group, virtual recording cells having a length of 385 nm are virtually set on the recording layer, and the irradiation time of the laser beam set to the recording power is set for each virtual recording cell. In other words, different recording marks were formed on multiple virtual recording cells.

Here, the maximum irradiation time for irradiating the virtual recording cell with the laser beam set to the recording power was 55 nsec.

Similarly, a different track of the same optical recording medium sample is irradiated with a laser beam whose recording power is set to 12.2 mW, and the laser beam set to the recording power is set for each virtual recording cell. By changing the irradiation time, different recording marks were formed in multiple virtual recording cells.

Further, similarly, a different track of the same optical recording medium sample is irradiated with a laser beam having a recording power set to 16 OmW, and a laser beam set to the recording power is set for each virtual recording cell. At different times, different recording marks were formed in multiple virtual recording cells.

In this way, a laser beam with a reproduction power P_r set to 1.3 mW is applied to the optical recording medium sample in which different recording marks are formed in a plurality of virtual recording cells, and the linear velocity is increased from the optically transparent substrate side. Irradiate at 7.0 m / sec, measure the amount of laser beam reflected by each virtual recording cell, measure the light reflectance of each virtual recording cell, the irradiation time of the laser beam set to the recording power, and Was measured.

The measurement results are shown in FIG. In FIG. 8, the light reflectance on the vertical axis is represented by a voltage value (V) obtained by photoelectrically converting the laser beam reflected by each virtual recording cell. The light reflectance (V) in FIG. 8 is calibrated so that the light reflectance (V) of the virtual recording cell where no recording mark is formed becomes 1.0.

As shown in FIG. 8, as the recording power level of the laser beam is higher, the light reflectance of the virtual recording cell becomes shorter in a short time after the irradiation of the laser beam set to the recording power is started. As the irradiation time of the laser beam increased, it decreased almost linearly, and it was found that the length of the region A in FIG. 4 became shorter.

Also, as shown in Fig. 8, as the recording power of the laser beam is lower, even if the irradiation time of the laser beam is increased, the light reflectance of the virtual recording cell does not change much. It took a long time, and it was found that the length of the area C in FIG. 4 became short. When the recording power of the laser beam is set to 9.0 mW, the virtual recording cell is irradiated with the laser beam set to the recording power for 55 nsec, which is the maximum irradiation time. The light reflectance of the recording cell did not reach the saturated light reflectance.

Further, as shown in FIG. 8, the higher the recording power of the laser beam, the larger the change in the light reflectance of the virtual recording cell with the increase in the irradiation time of the laser beam in the region B in FIG. Was found.

Example 2

An optical recording medium sample was prepared in the same manner as in Example 1, and was set on an optical recording medium evaluation device “DDU 100” (trade name) manufactured by Pulstec Industrial Co., Ltd. At 7.0 m / sec, 3-bit data was recorded in each virtual recording cell according to the first recording condition and the second recording condition.

In the first recording condition, the maximum relative light reflectivity RRa assigned to the virtual recording cell was set to 85%, and the minimum relative light reflectivity RRh was set to 5%. The recording layer 21 was irradiated with a laser beam having a different recording power to record data.

On the other hand, in the second recording condition, the maximum relative light reflectance RRa assigned to the virtual recording cell was set to 95%, the minimum relative light reflectance RRh was set to 15%, and the laser beams having different recording powers were set. Was applied to the recording layer 21 to record data.

A laser beam with a power level set to 1.3 mW was applied to the optical recording medium sample on which data was recorded according to the first recording condition and to the optical recording medium sample on which data was recorded according to the second recording condition. The system was irradiated at a linear velocity of 7.0 m // sec, the data was reproduced, the error rate (DSER) was measured, and the relationship between the recording power of the laser beam and the error rate was measured.

The measurement results are shown in FIG.

As shown in FIG. 9, according to the first recording condition, in the optical recording medium sample on which the data was recorded, the recording power at which the error rate (DSER) became the minimum was about 8 mW, According to the second recording condition, in the optical recording medium sample on which the data was recorded, the recording power w at which the error rate (DSER) was minimum was about 11 mW, and the low maximum relative light reflection was applied to the virtual recording cell. If a low relative light reflectance is assigned, the recording power w of the laser beam is set to a low level, and a high maximum relative light reflectance and a high minimum relative light reflectance are assigned to the virtual recording cell. In this case, it was confirmed that it is preferable to set the recording power of the laser beam to a high level. The present invention is not limited to the embodiments and examples described above, and various modifications can be made within the scope of the invention described in the appended claims, which are also included in the scope of the present invention. Needless to say, it is.

For example, in the above-described embodiment and the above-described embodiment, in the write-once DVD-R type optical recording medium, the force S described above for recording data is described. Record data on media However, the present invention is not limited to this case, and can be applied to the case where data is recorded on another optical recording medium.

Further, in the embodiment and the example, the optical recording medium 1 irradiates the recording layer 21 with a laser beam through the light transmitting substrate 11 to record data, and the data is recorded on the recording layer 21. Although it is configured to reproduce recorded data, the optical recording medium 1 irradiates a laser beam to the recording layer 21 through the light-transmitting substrate 11 to record data, and It is not always necessary to be configured to reproduce the data recorded in 21. The present invention provides a reflective layer, a recording layer, and a protective layer on a substrate in this order, and through the protective layer. The present invention can also be applied to a case where a recording layer is irradiated with a laser beam to record data, and data recorded on an optical recording medium configured to reproduce the data recorded on the recording layer. In the embodiment, each virtual record Although 3-bit data is recorded in the cell S, the present invention is not limited to the case where 3-bit data is recorded in each virtual recording cell S, but is recorded in each virtual recording cell S. It can be widely applied when recording data of 2 bits or more.

Further, in the above embodiment, when 3-bit data is recorded in each virtual recording cell S, the maximum light reflectance Ra, the maximum relative light reflectance RRa, and the minimum light reflection allocated to the virtual recording cell S are determined. The reflectance Rh and the minimum relative light reflectance RRh are set, and the maximum light reflectance Ra and the minimum light reflectance Rh or between the maximum relative light reflectance RRa and the minimum relative light reflectance RRh are set. Into approximately seven equal parts and determine six different types of light reflectance R b, R c, R d, Re, R f, and R g, but the maximum to be assigned to the virtual recording cell S It is not always necessary to set the light reflectivity R a and the maximum relative light reflectivity RR a and the minimum light reflectivity R h and the owl small relative light reflectivity RR h, and it is not necessary to set the maximum light reflectivity R assigned to the virtual recording cell S. a and the maximum relative light reflectance RR a or the minimum light reflectance R h and Set the minimum relative reflectance RR h, the maximum light reflectance R a and the maximum relative light reflectance allocated to the virtual recording cells S R R. a, or The laser beam reflected from the virtual recording cell S is detected in the virtual recording cell S having a different recording level based on the minimum light reflectance R h and the minimum relative light reflectance RR h assigned to the virtual recording cell S, and the data is obtained. When reproducing the data, it is possible to assign a different light reflectance or relative light reflectance according to the light reflectance difference or relative light reflectance difference at which the difference in data recording level can be recognized.

Further, in the above embodiment, when the laser beam reaches the starting point of the virtual recording cell S where the recording mark is to be formed, the laser beam is raised from the base power to the recording power _Pw. However, if the total energy of the laser beam applied to the virtual recording cell s is the same, the timing of raising the power of the laser beam from the base power to the recording power w can be arbitrarily determined.

Further, in the embodiments and the examples, the optical recording medium includes the recording layer containing the organic dye material. However, it is not always necessary that the optical recording medium includes the recording layer containing the organic dye material. Alternatively, a recording layer containing an inorganic material may be provided.

According to the present invention, when data of 2 bits or more is recorded on an optical recording medium, and when data recorded on the optical recording medium is read, a difference in data recording level can be reliably determined. It is possible to provide a data recording condition determination method capable of determining data recording conditions so that a reproduction signal having a dynamic range can be obtained. Further, according to the present invention, it is possible to record data of 2 bits or more on an optical recording medium and to reliably determine a difference in data recording level when reading data recorded on the optical recording medium. It is possible to provide a data recording device that can record data on an optical recording medium by determining data recording conditions so that a reproduced signal having a wide dynamic range can be obtained. Become.

Claims

The scope of the claims

1. When recording data of 2 bits or more in a plurality of virtual recording cells virtually set in a recording layer of an optical recording medium, the maximum light reflectance and / or the minimum light reflectance allocated to the virtual recording cells A method for determining data recording conditions, comprising setting recording power of a laser beam used for recording data in accordance with light reflectance.

2. The data recording condition determining method according to claim 1, wherein the recording power of the laser beam is set to a higher level as the maximum reflectance assigned to the virtual recording cell is higher.

3. The data recording condition determination method according to claim 1, wherein the recording power of the laser beam is set to a lower level as the minimum reflectance assigned to the virtual recording cell is lower.

4. The higher the maximum relative reflectivity assigned to the virtual recording cell, the higher the recording power of the laser beam is set, and the maximum relative light reflectivity RR aH and the minimum relative light reflectivity RR hH are set to 100—RRaH < 3. The data recording condition determination method according to claim 2, wherein the setting is made so as to satisfy R RhH.

5. The lower the minimum reflectivity assigned to the virtual recording cell, the lower the recording power of the laser beam is set to a lower level, and the maximum relative light reflectivity R RaH and the minimum relative light reflectivity RRhH are set as 100—RRa> RRh. 4. The method for determining data recording conditions according to claim 3, wherein L is set so as to satisfy L.

6. The optical recording medium according to any one of claims 1 to 5, wherein the recording layer of the optical recording medium contains an organic dye material. Method for determining recording conditions for data.

7. When recording data of 2 bits or more in a plurality of virtual recording cells virtually set in the recording layer of the optical recording medium, the maximum light reflectance and / or maximum optical reflectance to be allocated to the virtual recording cells. depending on the minimum reflectance, the data recording apparatus, characterized in that the recording Pawa one laser beam storing recording condition setting data set used to record the data _t

8. The recording power of the laser beam is set to a higher level as the maximum reflectance assigned to the virtual recording cell is higher, and the recording condition setting data is generated. The data recording device according to item 7.

9. The recording power of the laser beam is set to a lower level as the maximum reflectance assigned to the virtual recording cell is lower, and the recording condition setting data is generated. Item 8. The data recording device according to Item 7.

10. The recording power of the laser beam is set to a higher level as the maximum relative reflectance assigned to the virtual recording cell is higher, and the maximum relative light reflectance RRaH and the minimum relative light reflectance RRhH are 1 9. The data according to claim 8, wherein the recording condition setting data is generated so as to satisfy 0 0—RR a H <RR h H.

11. The lower the minimum reflectance assigned to the virtual recording cell, the lower the recording power of the laser beam is set to a lower level, and the maximum relative light reflectance

RR a H and a minimum relative light reflectance RR h H are set so as to satisfy 100—RR a L> RR h L, and the recording condition setting data is generated. Data record described in paragraph 9 of the scope

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