WO2003028013A1

WO2003028013A1 - Multi-level optical recording medium, multi-level reproducing method and reproducing device

Info

Publication number: WO2003028013A1
Application number: PCT/JP2002/009535
Authority: WO
Inventors: Hiroyuki Arioka; Syuji Tsukamoto; Narutoshi Fukuzawa; Takashi Horai; Hiroshi Take; Motohiro Inoue
Original assignee: Tdk Corporation
Priority date: 2001-09-21
Filing date: 2002-09-17
Publication date: 2003-04-03
Also published as: JP2003099947A

Abstract

A multi-level optical recording medium (10) capable of recording record data according to a multi-level recording method specifying the light reflectance of a recording part in a recording layer (12) in a multi-stage manner. Laser power information specifying the emission power of the laser beam to be emitted toward the multi-level optical recording medium (10) when reproducing the record data recorded in the recording layer (12) is recorded in the multi-level optical recording medium in a readable manner. The multi-level optical recording medium (10) can improve the reading accuracy without any reproduction degradation when reproducing the record data.

Description

Itoda »

Multi-level optical recording medium, multi-level reproduction method and reproduction apparatus

The present invention relates to a multi-level optical recording medium capable of recording data according to a multi-level recording method, a multi-level reproducing method for reproducing recorded data recorded on the multi-level optical recording medium, and a reproducing apparatus. .

Background art

Currently, as an optical recording medium, binary data is recorded by forming a pit by irradiating a laser beam set to the recording power, and the binary data can be reproduced based on the presence or absence of the pit. Binary 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, research on a recording method for recording recording data at a high density by adjusting a condensing beam diameter of a laser beam applied at the time of recording has been advanced.

On the other hand, unlike the method of adjusting the focused beam diameter, 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, a part of a recording layer (a part of one virtual recording cell to be recorded) in the optical recording medium is changed by switching an emission amount of a laser beam to be irradiated during recording in multiple steps. An altered portion (hereinafter, also referred to as a “recording mark”) that lowers the light transmittance appears at the same time, and the ratio of this recording mark to the entire virtual recording cell in one virtual recording cell is radiated during the recording. The property that it varies depending on the amount is used. In other words, this multi-level optical recording medium is affected by the light transmittance of the virtual recording cell where the recording mark is formed when the laser beam set to the reproduction power is irradiated, and as a result, this laser The light reflectivity of the beam is multi-step (for example, 5 steps or more). Therefore, each of a plurality of data contents is made to correspond to each of the multi-stage light reflectance. As a result, one of the plurality of data is recorded in one virtual recording cell. In this case, the light transmittance is the ratio of the laser beam that has passed through the virtual recording cell to the laser beam set to the reproducing power applied to the virtual recording cell.

The light reflectance is defined as the virtual beam after the laser beam set to the reproducing power applied to the virtual recording cell is reflected by the reflection layer of the multi-level optical recording medium through this virtual recording cell. The ratio of the laser beam that passes through the recording cell again and is emitted outside the multi-level optical recording medium.

When reproducing recorded data recorded on this multi-level optical recording medium (hereinafter also referred to as “multi-level reproduction”), the light reflectance of a virtual recording cell irradiated with a laser beam set to the reproduction power is The recording data is reproduced by specifying the order of the light reflectance of the multi-stage light reflectance. In this case, in the multilevel optical recording medium, the size of the virtual recording cell S is binary, in order to record the recording data (recording mark M) at a higher density than a general binary optical recording medium. It is specified smaller than the pit of the optical recording medium.

For this reason, when the output power of the laser beam is specified to be approximately the same as the output power of the laser beam specified for a general binary optical recording medium (in this case, 0.7 mW or less) during multi-level reproduction However, a reduction in the ratio of the signal component to the reflected light (CZN: also referred to as “SNR”) leads to a reduction in the reading accuracy of recorded data and the occurrence of tracking errors due to high-speed rotation. It will be. Also, the size of the recording mark M is smaller than the wavelength (λ) of the laser beam irradiated during reproduction and the numerical aperture (NA) of the pickup that emits one laser beam during reproduction. XNA) If the value is below, two or more recording marks M may be included in the focused beam diameter D of the laser beam irradiated during reproduction (see Fig. 2). At this time, if the output power of the laser beam irradiated during reproduction is small, of the two recording marks M, M in the focused beam diameter D, for example, the recording mark M to be read is the recording mark M a to M g. Correctly determine which one Can be difficult to read. Therefore, the inventor tried to improve these points by increasing the output power of the laser beam during multi-level reproduction. Disclosure of the invention

However, this multilevel optical recording medium and its reproducing method have the following points to be improved. In other words, in this multi-level optical recording medium, the emission power of the laser beam to be irradiated at the time of reproduction is set to the same value as that of the binary optical recording medium in order to prevent a decrease in reading accuracy and the occurrence of a tracking error at the time of reproducing the recorded data. It is necessary to specify a high output exceeding the output power of the laser beam at the time of birth. However, when the multi-level optical recording medium is repeatedly irradiated with a high-power laser beam, the irradiation of the laser beam deteriorates the recording layer of the multi-level optical recording medium and lowers the signal level. As a result, the SNR is reduced (hereinafter, also referred to as “reproduction degradation”), which may make it difficult to normally reproduce recorded data. This is probably due to the deterioration of the dye and the phase transition of the phase change material. Also, if the output power of the laser beam irradiated during reproduction is specified to be small, reproduction deterioration can be avoided, but as described above, reading accuracy will decrease and tracking errors will occur. However, with regard to this multi-level recording medium, the range of the emission pattern of the laser beam irradiated during reproduction, which can improve read accuracy while avoiding reproduction deterioration, is still clarified! It is preferable to improve this point.

In this case, the emission power of the laser beam irradiated at the time of reproduction, which can improve read accuracy while avoiding reproduction deterioration, depends on the material used for the recording layer of the multi-level optical recording medium to be reproduced and the multi-level optical recording medium. It differs depending on the thickness of each of the various resin layers and the recording layer constituting the optical recording medium. In particular, when an organic dye-based material is used as the recording layer, this difference becomes remarkable. Therefore Originally, a laser beam with the optimum output power (output power that can improve reading accuracy while avoiding reproduction degradation) is emitted to the multi-level optical recording medium for the playback device. It is preferred that

The present invention has been made in view of the above points to be improved, and a multi-level optical recording medium, a multi-level reproducing method, and a reproducing apparatus capable of improving reading accuracy without causing reproduction deterioration when reproducing recorded data. SUMMARY OF THE INVENTION A multi-level optical recording medium according to the present invention has a main object to provide a multi-level optical recording medium in which recording data can be recorded according to a multi-level recording method in which a light reflectance of a recording portion in a recording layer is defined in multiple steps. A multi-level optical recording medium, wherein laser power information for specifying the emission power of one laser beam to be emitted toward the multi-level optical recording medium at the time of reproducing the recording data recorded on the recording layer is readable. It is recorded and configured.

In this case, it is preferable to record, as the laser power information, information for specifying a recommended value of the emission power. Further, it is preferable that information specifying an upper limit value and a lower limit value of the emission power be recorded as the laser power information. Further, it is preferable to record, as the laser power information, information for specifying the emission power corresponding to the linear velocity of the multilevel optical recording medium during reproduction. In this multi-level optical recording medium, laser power information that specifies the emission power of the laser beam to be irradiated during reproduction is recorded in a readable manner. Therefore, when reproducing recorded data, the laser power information specified by the laser power information is used. As long as a single laser beam is emitted with power, SER (read error rate for true data) and BER (bit error rate) can be maintained at a level that does not interfere with reading recorded data. In addition to improving the reading accuracy of the multi-level optical recording medium, it is possible to effectively prevent the deterioration of the reproduction of the multi-level optical recording medium even when the reproduction is continuously performed. In addition, when the multi-level optical recording medium is loaded in a reproducing apparatus, the area is first read out by the reproducing apparatus, and the area can be specified by the area information recorded in the first read area. It is preferable to record laser power information. With this configuration, at the time of reproducing recorded data, the laser power information can be read out simply by loading the multi-level optical recording medium into the reproducing apparatus. The emission power of the laser power can be specified. As a result, the reproducing apparatus can surely and quickly reproduce the recorded data, and can surely prevent the deterioration of reproduction of the multi-level optical recording medium.

Further, it is preferable that the laser power information is recorded as a wobble signal of a group for guiding the laser beam. With this configuration, it is possible to avoid deterioration of the recorded contents due to aging, and as a result, it is possible to sufficiently improve the reading accuracy of the laser power information.

A multi-level reproduction method according to the present invention is a multi-level reproduction method for reproducing the recorded data recorded on the multi-level optical recording medium, wherein the reproduction target is reproduced prior to the reproduction of the recorded data. The laser power information is read from the multi-level optical recording medium, the laser beam is emitted toward the recording layer with the emission power specified based on the laser power information, and the light receiving level of the reflected laser beam The recorded data is reproduced based on Also, a reproducing apparatus according to the present invention is a reproducing apparatus for reproducing the recorded data recorded on the multi-level optical recording medium according to the multi-level reproducing method, wherein the laser beam is applied to the multi-level optical recording medium. A pickup that emits and receives the laser beam reflected by the multi-level optical recording medium and outputs an electric signal corresponding to the received light level; and controls the pickup to adjust the emission power of the laser beam. And a control unit for reproducing the recorded data based on the electric signal output by the pickup. The control unit reads the laser power information from the multi-level optical recording medium to be reproduced prior to reproduction of the recording data, so that the emission power is determined based on the laser power information. It is configured to drive and control the pickup.

In these multi-level reproducing methods and reproducing apparatuses, prior to reproducing recorded data, the emission power of a laser beam to be irradiated during reproduction is specified based on laser power information read from a multi-level optical recording medium to be reproduced. By setting, the SER and BER can be maintained at a level that does not hinder the reading of the recorded data.As a result, the reading accuracy of the recorded data can be improved, and even if the data is reproduced continuously, the multi-level can be obtained. It is possible to effectively prevent the reproduction deterioration of the optical recording medium.

This disclosure relates to the subject matter included in Japanese Patent Application No. 2001-2878792 filed on September 21, 2001, and Are hereby expressly incorporated by reference. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a partially cutaway perspective view showing the configuration of an optical recording medium 10 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 10.

FIG. 3 is a plan view of the optical recording medium 10.

FIG. 4 is a block diagram showing a configuration of the recording / reproducing apparatus 1. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of a multilevel optical recording medium, a multilevel reproducing method, and a reproducing apparatus according to the present invention will be described with reference to the accompanying drawings. First, the configuration of the multilevel optical recording medium 10 (hereinafter, also referred to as “optical recording medium 10”) according to the present invention will be described with reference to FIG.

The optical recording medium 10 is a CD-R type optical recording medium (write-once type optical recording medium) or a CD-RW type optical recording medium (rewritable type optical recording medium). As shown in FIG. It comprises at least a substrate 11, a recording layer 12, a reflective film 13 and a protective layer 14. The substrate 11 is injection-molded into a disk shape using a transparent resin as a base material, and transmits a laser beam applied during reproduction before the laser beam reaches the recording layer 12. On one surface (upper surface in FIG. 1) of the substrate 11, a groove 11 a for laser beam guide and a land 11 b are formed spirally from near the center to the outer edge. Have been. In the case of the CD-R type, the recording layer 12 is formed using organic dyes such as cyanine, merocyanine, methine dyes and derivatives thereof, benzene thiol metal complexes, phthalocyanine dyes, naphthalocyanine dyes, and azo dyes. The organic dye is formed by coating so as to cover the group 11a and the land 11b. On the other hand, CD- if the RW type, at least Z n S- S i O _2, etc. of the dielectric layer sandwiched by G e S b T e system and A g I n S b T phase change e system such as The recording layer 12 made of a material is formed by sputtering or the like. The recording layer 12 changes when irradiated with a laser beam set to the recording power by the recording device (degradation and deterioration in CD-R, phase change in CD-RW), and the irradiation of the laser beam Depending on the amount, its light transmittance changes. The reflection film 13 is a thin film layer for reflecting a laser beam that has passed through the substrate 11 and the recording layer 12 when reproducing the recorded data recorded on the optical recording medium 10, and is made of a material such as gold or silver. It is formed, for example, by sputtering on the recording layer 12 using 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.

As shown in FIG. 3, the optical recording medium 10 has a mounting center hole 10a for mounting the optical recording medium 10 in a recording / reproducing apparatus at the center thereof, and a mounting center hole. A lead-in area 10b and a data recording area 10c are formed around 10a. The lead-in area 10b is an area which is read first when the optical recording medium 10 is loaded into the recording / reproducing apparatus, and various kinds of information indicating the characteristics of the optical recording medium 10 are, for example, as a group wobble signal. Has been recorded. In this case, in the optical recording medium 10, in addition to the emission power data Dp corresponding to the laser power information in the present invention, information indicating that the optical recording medium 10 is a multi-level optical recording medium, and multi-level For example, information indicating that recording data by recording is recorded in seven levels is recorded in the lead-in area 10b. In addition, when the substrate 11 is molded, the pebbles are fixedly formed in advance as a very slight meander of the group 11a. Therefore, the deterioration of the wobble signal due to aging can be avoided, so that the accuracy of reading the wobble signal is improved. The data recording area 10c is an area for recording the recording data in the present invention, and has a recording layer 12 for recording the recording marks Ma to Mg as described later. .

Next, the recording principle of the optical recording medium 10 will be described with reference to FIGS. In this optical recording medium 10, as shown in FIG. 1, a virtual recording cell S, which is obtained by virtually dividing the group 11a in the data recording area 10c along the rotation direction (circumferential direction), S-· is specified (virtual) as a recording unit. Here, as shown in FIG. 2, the length of the virtual recording cell S in the direction along the group 11a (in the circumferential direction of the optical recording medium 10) is the focused beam diameter (diameter of the beam waist). It is specified to be, for example, 0.6 μπι shorter than D (eg, 1.5 μπι). In this case, the track pitch of the optical recording medium 10 divided by the width of the group 11a can be arbitrarily selected. In this optical recording medium 10, the unit width of the virtual recording cell S is, as shown in FIG. It is specified to be equal to or slightly smaller than the width of 11a (for example, 0.6 μπι). Therefore, the virtual recording cells S are efficiently arranged in the radial direction of the optical recording medium 10. It should be noted that the virtual recording cell S is merely a virtual one, and does not have an entity like a rectangle shown in FIG. In, it is assumed by the recording / reproducing device.

In this case, the emission time of the laser beam (that is, the emission amount of the laser beam) set on the recording beam emitted from the pickup of the recording device is controlled in multiple stages according to the value of the recording data. In the case of CD-R, as shown in FIG. 2, recording marks M a to M g having different degrees of degradation of the recording layer 12 (hereinafter also referred to as “recording mark M” when no distinction is made) Is formed in the virtual recording cell S. In FIG. 5, the degree of degradation is conceptually shown by the size of the recording mark M. In addition, the virtual recording cell S on which the recording mark M is formed becomes a recording portion in the recording layer 12. In addition, when recording data is recorded by a laser beam, the laser beam is emitted while rotating the optical recording medium 10, so that the recording mark M has an oval length according to the emission time.

When multi-level recording of recording data is performed on the optical recording medium 10, the light reflectance at the time of irradiating the laser beam set to the reproduction power to the portion including the virtual recording cell S is, for example, 7 levels (not yet). The degree of degradation (the amount of change in light transmittance) of each of the recording marks Ma to Mg is defined so that the recording marks become eight stages (including the recording part). In this case, the light reflectance increases as the degree of degradation of the recording layer 12 decreases. For this reason, the recording mark M is not recorded, the virtual recording cell S has the characteristic of the maximum light reflectance, and the smallest recording cell includes the virtual recording cell S on which the recording mark Ma is formed. The portion has the characteristic of the largest light reflectance among the recording marks M, and thereafter, the light reflectance decreases in the order of each portion including the virtual recording cell S in which the recording marks Mb to Mf are respectively formed, The portion including the virtual recording cell S where the largest recording mark Mg is formed has the characteristic of the minimum light reflectance. In this case, the “portion including the virtual recording cell S” means an irradiated portion of the recording layer 12 of the optical recording medium 10 where the laser beam set to the recording power or the reproduction power is focused. Therefore, it does not mean the number of virtual recording cells S. In other words, the focused portion of these laser beams is irradiated according to the focused beam diameter of each laser beam. Thus, a specific portion in one virtual recording cell S and a portion including one or more virtual recording cells S are included. Therefore, by controlling the emission amount of the laser beam set to the recording power for the portion including the virtual recording cell s, the area ratio of the degraded and altered portions (that is, the light transmittance of the recording layer 12) is appropriately set. In addition, it is possible to form the recording marks Ma to Mg whose light reflectivity when irradiated with the laser beam set to the reproducing power becomes seven steps.

Next, a recording / reproducing apparatus 1 for recording recording data on the optical recording medium 10 and reproducing the recording data will be described with reference to FIG.

The recording / reproducing apparatus 1 corresponds to the reproducing apparatus of the present invention, and is configured to be capable of reproducing recorded data according to the multi-level reproducing method of the present invention. The recording / reproducing apparatus 1 is a so-called CD-R / RW recorder, and includes a spindle motor 2, a pickup 3, a spindle servo 4, a feed servo 5, a focus tracking servo 6, and a controller 7. In this case, the spindle motor 2 is driven and controlled by a spindle servo 4 as described later, and rotates the optical recording medium 10 at a constant linear velocity.

The pickup 3 is formed by integrating a laser emitting section and a laser receiving section, and a laser (both not shown) is driven by a laser driver under the control of the control section 7 to record data on the optical recording medium 10. Either a laser beam set to the same value or a laser beam (output laser La) set to the reproduction power is emitted. Thereby, recording of the recording mark M on the virtual recording cell S and output of an electric signal corresponding to the level of the reflected laser Lb reflected by the virtual recording cell S on which the recording mark M is recorded are performed. In this case, at the time of reproducing the recorded data, the laser driver of the pickup 3 reads out the emission power data Dp recorded in the lead-in area 10b under the control of the control unit 7, and reads the emission power data. The output power corresponding to Dp (for example, 1.0 depending on the rotation speed of the optical recording medium 10).

O mW or more and within 2.5 mW or less). Adjust —. Further, the pickup 3 includes an objective lens and a half mirror (both not shown), and focuses a laser beam set to a recording power or a reproduction power on the recording layer 12 of the optical recording medium 10. Specifically, the focus tracking control of the objective lens is performed by the focus tracking servo 6, whereby these laser beams are focused on the recording layer 12 of the optical recording medium 10. The pickup 3 is reciprocated by a servo 5 between the inner peripheral side and the outer peripheral side thereof along the diameter direction of the optical recording medium 10.

The spindle servo 4 controls the rotation of the spindle motor 2 so that the linear velocity becomes a specified constant speed within a range of, for example, 9 m / g to 25 mZ seconds under the control of the control unit. The controller 7 controls the drive of the pickup 3, the spindle servo 4, the feed servo 5, and the focus tracking servo 6, and is recorded on the recording layer 12 based on the electric signal output from the pickup 3. Read the recorded data. Further, when the optical recording medium 10 is loaded into the recording / reproducing apparatus 1, the control unit 7 controls the drive of the pickup 3 to first read various information recorded in the lead-in area 10b. . At this time, the emission power of the emission laser La at the time of reproducing the optical recording medium 10 is defined based on the read emission power data Dp. In this case, the emission power data Dp corresponds to “information for specifying the upper limit value and the lower limit value of the emission power” in the present invention, and specifies the emission power corresponding to the linear velocity of the optical recording medium 10 during reproduction. Information. Specifically, for example, when the optical recording medium 10 is rotated at a linear velocity of 9 mZ seconds or more and 25 mZ seconds or less, the emission power of the laser beam during reproduction is 1.0 OmW (lower limit). Value) More than 2.5 mW (Upper limit value) It is composed of information that it is preferable to be within the following range.

Next, a description will be given of a recording data reproducing method for reproducing the recording data recorded on the optical recording medium 10 by the recording / reproducing apparatus 1.

When the optical recording medium 10 is loaded in the recording / reproducing apparatus 1, the control unit 7 By controlling the robot 4, the spindle motor 2 is driven to rotate the optical recording medium 10 at, for example, a linear velocity of 9 ms. At the same time, the controller 7 drives the feed servo 5 to move the pickup 3 to the lead-in area 10b. Next, the control unit 7 emits the emission laser beam La to the pickup 3 and drives the focus tracking servo 6 to perform focus tracking control of the objective lens of the pickup 3. At this time, the control unit 7 controls the drive of the pickup 3 to control the output power of the output laser La to a weak power (for example, 0.5 mW) fixedly specified in advance. As a result, the output laser La emitted by the pickup 3 is applied to the lead-in area 10b of the optical recording medium 10, and the reflected laser Lb is received by the pickup 3. At this time, the pickup 3 outputs an electric signal corresponding to various information recorded as, for example, a wobble signal in the lead-in area 10b, whereby the control unit 7 outputs an optical signal based on the electric signal. It is determined that the recording medium 10 is a multi-level optical recording medium and that the recording data is recorded by, for example, seven-stage multi-level recording without including the unrecorded portion. At the same time, the control unit 7 reads out the emission power data D p from the electric signal, and determines the emission power of the emission laser La at the time of recording data reproduction based on the emission power data D p. At this time, for example, it is assumed that the value is determined to be 1.1 mW.

Thereafter, the control section 7 drives and controls the spindle servo 4 to drive the feed servo 5 while maintaining the rotation speed of the optical recording medium 10 at a constant linear velocity of 9 seconds, thereby picking up. 3 is moved to the innermost peripheral group 11a in the data recording area 10c. Further, the control unit 7 drives and controls the pickup 3 so that the emission power (1.1 mW) of the emission laser La determined based on the emission power data Dp. As a result, the emitted laser beam La emitted from the pickup 3 irradiates the virtual recording cells S, S · · in the group 11 a in the optical recording medium 10, and is reflected by the reflection film 13. L b received by pickup 3 It is. At this time, the pickup 3 outputs an electric signal corresponding to each light reflectance of the recording marks Ma to Mg recorded in the virtual recording cells S 1, S 2. The recording data recorded on the optical recording medium 10 is read based on the electric signal. As a result, the recorded data is reproduced.

As described above, in the optical recording medium 10, the irradiation power data Dp is recorded in advance in the lead-in area 10 b at the time of manufacturing, so that it is irradiated to various reproduction devices at the time of reproduction. As a result, the optimum output power of the laser beam can be specified, so that the reading accuracy can be improved without causing reproduction deterioration. In this case, the output power of the laser beam irradiated during reproduction when the linear velocity is rotated within the range of 9 msec to 25 _m // sec should be within the range of 1.0 mW to 2.5 mW. By recording the information to the effect as emission power data Dp, it is possible to improve the reading accuracy of recorded data even for various multi-level optical recording media with different materials and thicknesses for each layer. And the deterioration of reproduction can be prevented.

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, the output power of the laser beam irradiated at the time of reproduction when rotated within the linear velocity range of 9 mZ seconds to 25 mZ seconds is set to 1.0 mW to 2.5 mW. An example has been described in which the emission power data Dp is configured with information (information specifying the upper limit value and the lower limit value in the present invention) defined within the following range, but the present invention is not limited to this. For example, the emission power can be defined in accordance with the linear velocity of the optical recording medium 10 during reproduction. Specifically, the output power when rotating at a linear velocity of 9 m // s is specified as 1.0 mW, and the output power when rotating at a linear velocity of 25 m / s is set to 2.5 mW. The output power data Dp may be configured with information indicating that it is preferable to define (information specifying a recommended value in the present invention). By recording this information, the reproducing apparatus can univocally determine the emission power according to the linear velocity. Can be.

Further, in the embodiment of the present invention, an example in which the emission power data Dp is recorded as a cobble signal in the lead-in area 10b has been described. However, the present invention is not limited to this. It is possible to record on the group 11a or land 11b by pre-pits, or to record on the recording layer 12 with a single laser beam set to the recording power. In this case, when the output power data Dp is recorded in the data recording area 10c, as shown by the broken line and the dashed line in FIG. 3, the recording is performed in the innermost or outermost part of the data recording area 10c. Is preferred. When the emission power data Dp is recorded in the data recording area 10c, area data Da (area information) for specifying the recording position (area in the present invention) is recorded in the lead-in area 10b. It is preferable to record it. When this configuration is adopted, when the optical recording medium 10 is loaded into the reproducing apparatus, the output power data Dp of the data recording area 10c is read according to the area data Da recorded in the lead-in area 10b. Is spilled out.

Further, in the embodiment of the present invention, an example in which the output power of the output laser La is set to 1.1 mW when the optical recording medium 10 is rotated at a linear velocity of 9 m / sec has been described. The invention is not limited to this. For example, when rotating at a linear velocity of 9 m / s or less, the range of the output power of the laser beam irradiated during reproduction (the lower limit is 1.0 mW and the upper limit is 2.5 mW) is proportional to the linear velocity. When the laser beam is rotated at a linear velocity exceeding 25 seconds, the output power of this laser beam (from the lower limit to the upper limit) is increased in proportion to the linear velocity, so that recording can be performed without deteriorating reproduction. Data can be reproduced normally. Further, the multi-level optical recording medium according to the present invention can be applied to a multi-level optical recording medium using an organic or inorganic material other than those described above for the recording layer 12 or a multi-level optical multi-level recording medium. The present invention can also be applied to a multilevel optical recording medium. Further, in the embodiment of the present invention, an example is shown in which the optical recording medium 10 is configured as a CD-R / RW type optical recording medium. However, the present invention is not limited to this, is generally applied to other optical recording media, and is not limited to a disk-shaped rotating body. Further, in the embodiment of the present invention, the optical recording medium 10 is configured to irradiate the laser beam set to the recording power and the reproduction power from the substrate 11 side, but the reflection layer and the recording layer are formed on the substrate. The present invention can also be applied to an optical recording medium having a configuration in which a protective layer is sequentially laminated and a laser beam set to recording power and reproducing power is irradiated from the protective layer side.

Industrial applicability

As described above, according to the multi-level optical recording medium of the present invention, since the laser power information for specifying the emission power of the laser beam irradiated at the time of reproduction is recorded in a readable manner, the reproduction of the recorded data is performed. In this case, as long as the laser beam is emitted with the emission power specified by the laser power information, the SER and BER can be maintained at a level that does not hinder the reading of the recorded data, and as a result, the reading accuracy of the recorded data is improved. In addition to this, it is possible to effectively prevent the deterioration of reproduction of the multi-level optical recording medium even when the reproduction is continuously performed. This realizes a multi-level optical recording medium capable of improving read accuracy without causing reproduction degradation when reproducing recorded data.

Claims

Scope of Word

1. A multi-level optical recording medium configured to be able to record data according to a multi-level recording method in which the light reflectance of a recording portion in a recording layer is defined in multiple steps,

A multi-level optical recording medium in which laser power information for specifying the emission power of a laser beam to be emitted toward the multi-level optical recording medium when reproducing the recording data recorded on the recording layer is recorded in a readable manner.

2. The multilevel optical recording medium according to claim 1, wherein information for specifying a recommended value of the emission power is recorded as the laser power information.

3. The multilevel optical recording medium according to claim 1, wherein information specifying an upper limit value and a lower limit value of the emission power is recorded as the laser power information.

4. The multilevel optical recording medium according to claim 1, wherein information specifying the emission power is recorded as the laser power information in correspondence with the linear velocity of the multilevel optical recording medium during reproduction.

5. The multilevel optical recording medium according to claim 2, wherein information specifying the emission power is recorded as the laser power information in correspondence with the linear velocity of the multilevel optical recording medium during reproduction.

6. The multilevel optical recording medium according to claim 3, wherein information specifying the emission power is recorded as the laser power information in correspondence with the linear velocity of the multilevel optical recording medium during reproduction.

7. The laser power information is, when the multi-level optical recording medium is loaded into a reproducing apparatus, an area which is read first by the reproducing apparatus and an area which can be specified by the area information recorded in the area which is read first. 2. The multilevel optical recording medium according to claim 1, wherein the medium is recorded in any one of the above.

8. The laser power information includes an area which is read first by the reproducing apparatus when the multi-level optical recording medium is loaded into the reproducing apparatus, and 3. The multi-level optical recording medium according to claim 2, wherein the information is recorded in any of the areas that can be specified by the area information recorded in the area to be read.

9. The laser power information is an area that is first read by the reproducing apparatus when the multilevel optical recording medium is loaded into the reproducing apparatus, and an area that can be specified by the area information recorded in the first area that is read. 4. The multilevel optical recording medium according to claim 3, wherein the medium is recorded in any one of the above.

10. The laser power information is specified by an area which is read first by the reproducing apparatus when the multi-level optical recording medium is loaded into the reproducing apparatus, and an area information recorded in the area which is read first. 5. The multilevel optical recording medium according to claim 4, wherein the medium is recorded in any of the possible areas.

11. The multi-level optical recording medium according to claim 1, wherein the laser power information is recorded as a wobble signal of a groove for guiding the laser beam.

12. The multi-level optical recording medium according to claim 2, wherein the laser power information is recorded as a wobble signal of a groove for guiding the laser beam.

13. The multilevel optical recording medium according to claim 3, wherein the laser power information is recorded as a wobble signal of a groove for guiding the laser beam.

14. The multi-level optical recording medium according to claim 4, wherein the laser power information is recorded as a wobble signal of a groove for guiding the laser beam.

15. The multi-level optical recording medium according to claim 7, wherein the laser power information is recorded as a wobble signal of a groove for guiding the laser beam.

16. Recording on the multilevel optical recording medium according to any one of claims 1 to 15 A multi-level reproduction method for reproducing the recorded data,

Prior to the reproduction of the recording data, the laser power information is read from the multi-level optical recording medium to be reproduced, and the laser beam is directed toward the recording layer at the emission pattern specified based on the laser power information. A multi-level reproducing method for emitting the recorded data based on a light receiving level of the laser beam emitted and reflected.

17. A reproducing apparatus for reproducing the recorded data recorded on the multi-level optical recording medium according to the multi-level reproducing method according to claim 16.

A pickup that emits the laser beam to the multi-level optical recording medium, receives the laser beam reflected by the multi-level optical recording medium, and outputs an electric signal according to the level of the received light; A control unit for controlling drive of the laser beam so as to adjust an emission power of the laser beam and reproducing the recording data based on the electric signal output by the pickup; A reproducing apparatus for reading out the laser power information from the multi-level optical recording medium to be reproduced before reproducing the data, and controlling the drive of the pickup so as to be an emission power specified based on the laser power information;