JP2005158174A - Data recording method and recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data recording method by which generation of tracking errors can be avoided in various optical recording media having a plurality of information layers. <P>SOLUTION: When data are recorded on an optical disk 10 by irradiating with a laser beam the optical disk 10 in which two information layers are formed, the data are recorded in a data-recording track in the first L2 information layer 14 from the laser beam incidence surface side and then an unrecorded data-recording track adjacent to the recorded data-recording track or an unrecorded data-recording track positioned in the vicinity of the recorded data-recording track is irradiated with the laser beam to form a transmittance adjustment region A2 having light transmittance intermediate between the transmittance of a recorded region A1 including the recorded data-recording track and the transmittance of an unrecorded region A0 including the unrecorded data-recording track. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a data recording method and a recording apparatus for recording recording data on an optical recording medium having a plurality of information layers.

  Optical recording media such as CDs and DVDs are widely used as information recording media for recording digital data. The recording capacity (capacity capable of recording recording data) required for such an optical recording medium increases year by year, and various proposals have been made to realize this requirement. As one of the proposals, there is a two-layer structure of an information recording layer (information layer), which is put into practical use in DVD-Video, DVD-ROM, and the like, which are read-only optical recording media. In recent years, a two-layer structure has been promoted for an optical recording medium in which recording data is written by a user. At the time of recording / reproducing recorded data on this type of optical recording medium, the information layer is irradiated with a laser beam adjusted to the recording power or the reproducing power. At this time, at the time of recording / reproducing the recording data with respect to the information layer on the back side in the irradiation direction of the laser beam, the laser beam emitted from the recording / reproducing apparatus is transmitted through the information layer on the front side in the irradiation direction. In this case, the transmittance with respect to the laser beam differs between the recorded area of the recorded data and the unrecorded area of the recorded data. Therefore, when a recorded area and an unrecorded area are mixed in the information layer on the front side in the irradiation direction, the transmittance with respect to the laser beam for tracking the information layer on the back side in the irradiation direction changes rapidly at the boundary between both areas. . As a result, tracking servo control may become difficult because the recording / reproducing apparatus cannot follow a rapid change in transmittance.

  On the other hand, as a data recording method for recording data on an optical recording medium having a two-layer structure, Japanese Patent Laid-Open No. 2000-285469 discloses a method for recording recording data on an optical disc 11. In this case, as shown in FIG. 1 of the publication, the optical disk 11 has a single-sided two-layer structure in which a first recording layer 12 (information layer) and a second recording layer 13 (information layer) are stacked with a transparent layer 14 interposed therebetween. have. When recording the recording data on the optical disc 11, first, the recording data is recorded on the first recording layer 12 positioned on the incident surface side of the irradiation light 15 (laser beam) to the optical disc 11. After recording data is recorded on the entire area of one recording layer 12, the recording data is recorded on the second recording layer 13. Specifically, as shown in FIG. 3 of the publication, the recording / reproducing apparatus (optical recording / reproducing apparatus) first accesses the first recording layer 12 (step S1), and the first recording layer 12 is not recorded. (That is, whether or not the optical disk 11 is a blank disk) (step S2). At this time, when it is determined that the first recording layer 12 is not recorded, recording of recording data to the first recording layer 12 is started (step S3). When recording of recording data is completed for the entire area of the first recording layer 12 (step S4), the recording / reproducing apparatus accesses the second recording layer 13 (step S5) and Recording of recording data is started (step S6).

On the other hand, if it is determined in step S2 that the first recording layer 12 is not unrecorded (that is, the optical disc 11 is not a blank disc), whether or not recording of recording data on the entire area of the first recording layer 12 is completed. Is discriminated (step S7). At this time, if recording of the recording data on the entire area of the first recording layer 12 is completed, the process proceeds to step S5 and recording of the recording data on the second recording layer 13 is started. Further, when recording of the recording data on the entire area of the first recording layer 12 is not completed (when there is an unrecorded area in the first recording layer 12), the unrecorded area of the first recording layer 12 is accessed. Then (step S8), recording of recording data on the unrecorded area is started (step S9). At this time, the recording data is recorded on the first recording layer 12 until the recording of the recording data on the entire area of the first recording layer 12 is completed, and then the process proceeds to step S5 and the recording data on the second recording layer 13 is recorded. Start recording. By recording the recording data on the optical disc 11 according to this recording method, it is not necessary to access the second recording layer 13 until the recording of the recording data on the first recording layer 12 is completed. Accordingly, the tracking control for the second recording layer 13 in the state where the recorded area and the unrecorded area are mixed in the first recording layer 12 becomes unnecessary, and the occurrence of the tracking error described above can be avoided.
JP 2000-285469 A (page 3-4)

  However, the conventional data recording method has the following problems. That is, in the conventional data recording method, recording data is recorded on the first recording layer 12 located on the front side of the irradiation direction of the irradiation light 15 on the optical disc 11, and recording data is recorded on the entire area of the first recording layer 12. After that, recording data is recorded on the second recording layer 13 located on the far side in the irradiation direction. This eliminates the need to access the second recording layer 13 in a state where the recorded area and the unrecorded area are mixed in the first recording layer 12, thereby avoiding the occurrence of a tracking error. In this case, in the optical recording medium having a two-layer structure, recording data is recorded in the information layer (recording layer) on the inner side in the irradiation direction at the time of manufacture (recording data is recorded by prepits), and the irradiation direction. Some of the information layers on the front side are configured so that the user can write recording data. Therefore, when using this type of optical recording medium, the information layer on the far side in the irradiation direction is accessed (recorded data is reproduced before recording data is recorded on the entire information layer on the near side in the irradiation direction). You may need to). However, the conventional data recording method avoids the occurrence of a tracking error when accessing the information layer on the far side in the irradiation direction until the recording of the recording data on the entire information layer on the near side in the irradiation direction is completed. Therefore, there is a problem that it is difficult to use this type of optical recording medium.

  The present invention has been made in view of such problems, and has as its main object to provide a data recording method and a recording apparatus capable of avoiding the occurrence of tracking errors in various optical recording media having a plurality of information layers. To do.

  In order to achieve the above object, a data recording method according to the present invention irradiates a laser beam onto an optical recording medium on which an information layer of N layers (N is a natural number of 2 or more) is formed, and records data on the optical recording medium. When recording, after the recording data is recorded on the data recording track in the M-th information layer (M is a natural number equal to or less than (N-1)) from the laser beam incident surface side, the recorded data recording is performed. By irradiating either the unrecorded data recording track adjacent to the recording track and the unrecorded data recording track located in the vicinity of the recorded data recording track with the laser beam A light transmittance of a recorded area including the recorded data recording track and a light transmittance of an unrecorded area including the unrecorded data recording track. Forming a transmittance adjusting region having a light transmittance.

  The information layer in the present invention is a functional layer including at least a recording layer, and is formed by, for example, a sputtering method. In this case, an information layer configured by adding a dielectric layer, a reflective layer, or the like to the recording layer is also included. Further, in the present invention, the “unrecorded data recording track adjacent to the recorded data recording track” means that the “recorded data recording track” is used when the data recording track is spiral. In the case where each data recording track is concentric, it means “a data recording track adjacent to a recorded data recording track”. In addition, when the data recording track is spiral, actually, the “recorded data recording track” and the “unrecorded data recording track” do not exist separately, One data recording track is formed from the inner periphery to the outer periphery of the optical recording medium. Therefore, in this specification, in order to facilitate understanding of the invention, a portion of the data recording track where recording of the recording data is completed is defined as a “recorded data recording track”, and recording is performed. A part where data is not recorded is defined as an “unrecorded data recording track”.

  In this case, it is preferable that the transmittance adjustment region is formed by irradiating at least one of the unrecorded data recording tracks with the laser beam.

  The width of the transmittance adjusting region along the radial direction of the optical recording medium is such that the M-th information layer is decentered with respect to the center of the optical recording medium and the (M + 1) -th information layer from the incident surface side. The amount of irradiation of the M-th information layer by the laser beam irradiated when tracking the (M + 1) -th information layer is subtracted from the total amount of the eccentricity with respect to the center of the optical recording medium. It is preferable to form the transmittance adjusting region so as to be wider than the length. Note that the amount of eccentricity of each information layer means the distance (absolute value) between the center of the optical recording medium and the center of each information layer regardless of the direction of eccentricity with respect to the center of the optical recording medium.

  Further, prior to the start of recording of the recording data on the Mth information layer, the transmittance adjustment region is formed by irradiating the unrecorded data recording track with the laser beam to form the transmittance adjustment region. It is preferable that recording of the recording data is started from either an unrecorded data recording track adjacent to the recording medium or an unrecorded data recording track located in the vicinity of the transmittance adjustment area.

  In addition, from the recorded area side to the unrecorded area side so that the light transmittance gradually changes from the light transmittance of the recorded area to the light transmittance of the unrecorded area in multiple steps or steplessly. It is preferable to form the transmittance adjusting region toward the surface.

  Further, the transmittance adjustment region is formed by continuously irradiating a laser beam having a power smaller than the laser beam irradiated at the time of recording the recording data and capable of changing the light transmittance of the irradiated portion. Is preferred.

  Further, it is preferable to form the transmittance adjusting region by irradiating a laser beam having a power capable of changing the light transmittance of the irradiated portion to record a recording mark for adjusting the transmittance.

The recording apparatus according to the present invention controls a pickup that irradiates a laser beam to an optical recording medium on which an information layer of N layers (N is a natural number of 2 or more) is formed, and controls the irradiation of the laser beam by the pickup. And a control unit for recording recording data on the optical recording medium,
The control unit irradiates the laser beam from the pickup toward the data recording track in the M-th information layer (M is a natural number equal to or less than (N−1)) from the laser beam incident surface side. After recording data, an unrecorded data recording track adjacent to the recorded data recording track, and an unrecorded data recording track located near the recorded data recording track By irradiating any one of the above, the light transmittance of the recorded area including the recorded data recording track and the light transmission of the unrecorded area including the unrecorded data recording track A transmittance adjustment region having a light transmittance intermediate to the transmittance is formed.

  According to the data recording method and the recording apparatus of the present invention, after recording the recording data on the data recording track in the Mth information layer, the intermediate between the light transmittance of the recorded area and the light transmittance of the unrecorded area. By forming a transmittance adjustment region having a light transmittance of (2), a state in which the laser beam that irradiates the (M + 1) th information layer is transmitted through the recorded region, and a state is transmitted through the outer periphery of the recorded region. It is possible to avoid a sudden change in the light transmittance when shifting between the two. Therefore, it is possible to avoid the occurrence of a tracking error for the (M + 1) th information layer. As a result, even if the recording data is not recorded over the entire information layer (Mth information layer) on the front side in the laser beam irradiation direction, the information layer ((M + 1) th on the back side in the irradiation direction is not recorded. For example, the information layer on the back side in the irradiation direction is a reproduction-only type (the type in which the recording data is recorded in advance in the information layer on the back side in the irradiation direction). Even for a layered optical recording medium, recording data can be reliably recorded in the information layer on the near side in the irradiation direction without hindering tracking on the information layer on the far side in the irradiation direction.

  Further, according to the data recording method of the present invention, the transmittance adjustment region is formed by irradiating the laser beam to at least one of the unrecorded data recording tracks, thereby forming the periphery of the recorded region. The transmittance adjustment area for one track of the data recording track can alleviate a sudden change in the transmittance when the laser beam passes across the recorded area and the unrecorded area, so there is no transmittance adjustment area. Compared with an optical recording medium, the occurrence of tracking errors can be sufficiently avoided.

  Furthermore, according to the data recording method of the present invention, the width of the optical recording medium in the radial direction in the transmittance adjustment region irradiates the Mth information layer from the total amount of eccentricity for both information layers. By forming the transmittance adjustment region so as to be wider than the length obtained by reducing the width of irradiation due to, the occurrence of a tracking error for the (M + 1) th information layer can be sufficiently avoided. In addition, since the difference between the maximum value and the minimum value of the light transmittance per rotation of the optical information medium can be reduced, a reproduction signal at the time of reproducing recorded data recorded in the information layer on the far side in the irradiation direction As a result, it is possible to sufficiently prevent the occurrence of a reproduction error.

  Further, according to the data recording method of the present invention, prior to the start of recording of the recording data on the Mth information layer, a transmittance adjustment region is formed by irradiating a laser beam onto an unrecorded data recording track. The recording of recording data from one of the data recording track adjacent to the transmittance adjustment region and the data recording track located in the vicinity of the transmittance adjustment region is started, so that the Mth information layer is recorded. Even in the vicinity of the recording start portion of the recording data, when the laser beam that irradiates the (M + 1) th information layer passes between a state where it passes through the recorded region and a state where it passes outside the recorded region. A sudden change in the light transmittance at can be avoided. As a result, it is possible to avoid occurrence of a tracking error for the (M + 1) th information layer.

  Further, according to the data recording method of the present invention, the transmittance adjustment region is set so that the light transmittance gradually changes from the light transmittance of the recorded region to the light transmittance of the unrecorded region in multiple steps or steplessly. By forming, the light transmittance at the boundary between the recorded area and the transmittance adjustment area and the boundary between the transmittance adjustment area and the non-recorded area can be gradually changed, so the (M + 1) th information layer It is possible to more reliably avoid the occurrence of tracking errors with respect to.

  Further, according to the data recording method of the present invention, a laser beam having a power lower than that of the laser beam irradiated at the time of recording the recording data and capable of changing the light transmittance of the irradiated portion is continuously irradiated. By forming the transmittance adjustment region, it is possible to avoid the occurrence of a tracking error for the (M + 1) th information layer while eliminating the need for complicated control over the servo mechanism.

  Furthermore, according to the data recording method of the present invention, the transmittance adjustment region is formed by irradiating a laser beam having a power capable of changing the light transmittance of the irradiated portion to record the recording mark for transmittance adjustment. As a result, the presence of the recording mark recorded on the data recording track forms a transmittance adjustment region whose light transmittance is intermediate between the light transmittance of the recorded region and the light transmittance of the unrecorded region. The occurrence of tracking errors can be sufficiently avoided. In addition, since the difference between the maximum value and the minimum value of the light transmittance per rotation of the optical information medium can be reduced, a reproduction signal at the time of reproducing recorded data recorded in the information layer on the far side in the irradiation direction As a result, it is possible to sufficiently prevent the occurrence of a reproduction error.

  The best mode of a data recording method and recording apparatus according to the present invention will be described below with reference to the accompanying drawings.

  First, the configuration of the recording / reproducing apparatus 1 will be described with reference to the drawings.

  A recording / reproducing apparatus 1 shown in FIG. 1 is a recording apparatus that records recording data on an optical disc 10 according to the data recording method of the present invention. For example, the recording / reproducing apparatus is connected to a personal computer (not shown) and output from the personal computer. The data is recorded on the optical disc 10 and the recorded data recorded on the optical disc 10 is read and output to a personal computer. In this case, the optical disk 10 corresponds to the optical recording medium in the present invention, and is an optical recording medium having a single-sided two-layer structure (an example in which N is 2 in the present invention) as an example. As shown in FIG. The layer 12, the spacer layer 13, the L2 information layer 14, and the light transmission layer 15 are formed on the base material 11 in this order. Further, a mounting center hole 10a for mounting on the recording / reproducing apparatus 1 is formed at the center of the optical disc 10, and is mounted on the recording / reproducing apparatus 1 with the light transmission layer 15 facing downward, for example. In the optical disc 10, the surface of the light transmission layer 15 corresponds to the “laser beam incident surface” in the present invention. The center of the mounting center hole 10 a (that is, the center of rotation) is the center of the optical disc 10.

  The base material 11 is manufactured by injection molding using polycarbonate as an example, and grooves and lands (for example, a spiral shape) for the L1 information layer 12 are formed on the surface (upper surface in FIG. 2). . The L1 information layer 12 corresponds to the (M + 1) th information layer in the present invention, and as an example, the second dielectric layer, the recording film, and the first dielectric layer are arranged in this order so as to cover the base material 11. A film is formed. The spacer layer 13 is formed by spin-coating a resin material having optical transparency so as to cover the L1 information layer 12, and on the surface (upper surface in FIG. 2), grooves and lands for the L2 information layer 14 ( As an example, a spiral shape) is formed. The L2 information layer 14 corresponds to the Mth information layer in the present invention, and is configured by forming the second dielectric layer, the recording film, and the first dielectric layer in this order so as to cover the spacer layer 13. Has been. The light transmission layer 15 is a layer for preventing the L2 information layer 14 and the like from being scratched, and for forming an optical path such as a laser beam La, and is a resin having a light transmission property so as to cover the L2 information layer 14. The material is formed by spin coating.

  This optical disc 10 is configured so that recording data can be recorded on the L1 information layer 12 in the groove formed on the substrate 11 and the L2 information layer 14 in the groove formed on the spacer layer 13. In this case, in this optical disc 10, as an example, the distance L between the L1 information layer 12 and the L2 information layer 14 (that is, the thickness of the spacer layer 13: see FIG. 3) is defined as 25 μm. The optical refractive index (n) is defined as 1.55. Further, in this optical disc 10, the light transmittance of the L2 information layer 14 changes before and after recording of recording data. Specifically, the average light transmittance of an area including data recording tracks in which recorded data is not recorded (recorded marks are not formed) (hereinafter also referred to as “unrecorded area A0”) is about 54%. On the other hand, the average light transmittance of an area including a data recording track (hereinafter also referred to as “recorded area A1”) in which recording of recording data is completed (recording mark is formed) is about 60%.

  Further, as shown in FIG. 4, in this optical disc 10, the center O2 (L1 information layer) of the L1 information layer 12 is caused by the misalignment of the stamper during the injection molding of the base material 11 or the formation of the spacer layer 13. 12 and the center O4 of the L2 information layer 14 (the center of each data recording track in the L2 information layer 14) are displaced from the center O of the optical disc 10. In the figure, in order to facilitate understanding of the present invention, the amount of eccentricity of the L1 information layer 12 and the L2 information layer 14 with respect to the center O is exaggerated and greatly decentered. In this case, the maximum eccentricity E2 (the distance between the centers O and O2) of the L1 information layer 12 is an allowable eccentricity of 50 μm at the maximum according to the standard defined for the optical disc 10. Further, the maximum eccentricity E4 (the distance between the centers O and O4) of the L2 information layer 14 is 75 μm at the maximum according to the standard. Therefore, as shown in the figure, in the state where the center O2 of the L1 information layer 12 and the center O4 of the L2 information layer 14 are eccentric so as to be opposite to each other with the center O of the optical disk 10 interposed therebetween, the L1 information layer The total amount E of the eccentricity of the L2 information layer 14 with respect to 12 is 125 μm at the maximum. For this reason, as will be described later, the recording / reproducing apparatus 1 is configured so that the recording / reproducing of the recording data can be normally executed even if the centers O2, O4 are eccentric to a maximum of 125 μm. The eccentric amounts of the L1 information layer 12 and the L2 information layer 14 with respect to the rotation center of the optical disc 10 are calculated based on the amount of movement of the pickup following the data recording track per revolution of the optical disc 10. Can do.

  On the other hand, the recording / reproducing apparatus 1 includes a rotation mechanism 2, a servo mechanism 3, a pickup 4, and a controller 5, as shown in FIG. The rotation mechanism 2 holds the edge of the mounting center hole 10 a in the optical disc 10 and rotates the optical disc 10 under the control of the controller 5. The servo mechanism 3 moves the pickup 4 along the radial direction of the optical disc 10 under the control of the controller 5. The pickup 4 irradiates the optical disc 10 with the laser beam La according to the control signal output from the controller 5 and receives the reflected light Lb reflected by the L1 information layer 12 or the L2 information layer 14 of the optical disc 10 to receive the light. The electrical signal corresponding to is output to the controller 5. In this case, for example, the pickup 4 includes an objective lens having a numerical aperture (NA) of 0.85, and emits a laser beam La having a wavelength of 405 nm. The controller 5 corresponds to a control unit in the present invention, controls the rotating mechanism 2 and the servo mechanism 3, and controls the pickup 4 to record recording data on the optical disc 10 and read (reproduce) recording data from the optical disc 10. To control.

  Next, a data recording method for recording record data on the optical disc 10 by the recording / reproducing apparatus 1 will be described with reference to the drawings.

  When recording data is recorded on the optical disk 10 (for example, a blank disk) by the recording / reproducing apparatus 1, recording of recording data is started from the inner periphery side of the L1 information layer 12 as an example, and the L1 information layer 12 is recorded. When the recording of the recording data for the entire area is completed, the recording data is recorded from the inner peripheral side of the L2 information layer 14. Therefore, when recording data to be recorded on the optical disk 10 is output from a personal computer or the like, the recording / reproducing apparatus 1 first rotates the optical disk 10 with respect to the rotating mechanism 2 and controls the servo mechanism 3 to pick up the recording data. 4 is moved to the inner peripheral side of the optical disk 10. Next, the controller 5 controls the pickup 4 to irradiate the laser beam La with the L1 information layer 12 in focus, and controls the servo mechanism 3 based on the light receiving state of the reflected light Lb to control the pickup 4. Tracking servo control.

  Next, the controller 5 irradiates the laser beam La adjusted to the recording power by controlling the pickup 4 based on the recording data output from the personal computer or the like. As a result, a recording mark corresponding to the recording data is formed at a portion of the L1 information layer 12 irradiated with the laser beam La. Next, when recording of the recording data on the entire area of the L1 information layer 12 is completed, the controller 5 controls the servo mechanism 3 to move the pickup 4 to the inner peripheral side of the optical disk 10. Subsequently, the controller 5 controls the pickup 4 to irradiate the laser beam La in a state where the L2 information layer 14 is focused, and controls the servo mechanism 3 based on the light reception state of the reflected light Lb to control the pickup 4. Tracking servo control. Next, the controller 5 irradiates the laser beam La adjusted to the recording power by controlling the pickup 4 based on the recording data output from the personal computer or the like. As a result, a recording mark corresponding to the recording data is formed at a portion of the L2 information layer 14 irradiated with the laser beam La.

  Next, when the recording of all the recording data output from the personal computer or the like is completed, the controller 5 is arranged around the data recording track where the recording of the recording data in the L2 information layer 14 is completed (data recording after recording is completed). The average light transmittance is about 57% in any of the data recording track adjacent to the recording track and the data recording track located in the vicinity of the recorded data recording track). A transmittance adjustment region A2 (see FIG. 4) is formed. At this time, as shown in FIG. 4, for example, when recording data is recorded from the innermost data recording track of the L2 information layer 14 to the data recording track T14, the data recording track T14 (recorded area A1) is recorded. ) Is formed in the transmittance adjustment region A2 having a width W (for example, about 100 μm).

  Specifically, the controller 5 controls the servo mechanism 3 while rotating the optical disk 10 with respect to the rotating mechanism 2 to sequentially move the pickup 4 from the data recording track T14 toward the outer data recording track T14a. While moving (tracking), the pickup 4 is controlled so that the light transmittance of the irradiated region is sufficiently larger than the laser beam La irradiated at the time of tracking and having a power smaller than that of the laser beam La irradiated at the time of recording the recording data. The L2 information layer 14 is continuously irradiated with a laser beam La having a power that can be changed. At this time, when the pickup 4 is tracking the data recording track adjacent to the data recording track T14, the controller 5 adjusts the power of the laser beam La to be slightly smaller than the recording power. As the pickup 4 moves away from the data recording track T14, the power of the laser beam La is adjusted so as to gradually decrease steplessly and irradiated. Thereby, the light transmittance of the L2 information layer 14 at the portion irradiated with the laser beam La is gradually changed steplessly, and a transmittance adjustment region A2 having a width W is formed around the recorded region A1. . Thereby, recording of the recording data on the optical disc 10 is completed.

  On the other hand, when reproducing the optical disk 10 on which the recording data is recorded according to the above-described data recording method, the controller 5 controls the pickup 4 to irradiate the optical disk 10 with the laser beam La adjusted to the reproduction power. At this time, for example, when reproducing the recording data recorded on the L1 information layer 12, the controller 5 controls the pickup 4 to irradiate the laser beam La in a focused state on the L1 information layer 12, Based on the light receiving state of the reflected light Lb, the servo mechanism 3 is controlled to perform tracking servo control of the pickup 4. Further, the controller 5 reads the recording mark recorded on the L1 information layer 12 based on the light receiving state of the reflected light Lb emitted from the pickup 4 and reflected by the L1 information layer 12, thereby recording the recording mark. Play the data. In this case, the optical disk 10 has a transmittance adjustment area A2 having an average light transmittance of about 57% between the recorded area A1 and the unrecorded area A0 when recording data on the L2 information layer 14. Is formed. Therefore, when the data recording track is tracked from the inner circumference side to the outer circumference side of the L1 information layer 12, light transmission with respect to the laser beam La is performed between the recorded area A1 and the unrecorded area A0 of the L2 information layer 14. The situation where the rate changes rapidly is avoided.

  In this case, in this optical disc 10, the spacer layer 13 is formed using a resin material having a refractive index (n) of 1.55 in a cured state so that the distance L between the L1 information layer 12 and the L2 information layer 14 is 25 μm. Is formed. Further, at the time of recording / reproducing recorded data on the optical disc 10, the laser beam La is irradiated by the pickup 4 having an objective lens having a numerical aperture (NA) of 0.85. Therefore, as shown in FIG. 3, when the laser beam La emitted from the pickup 4 is focused on the L1 information layer 12, the angle θ in FIG. 3 is about 33.3 ° (“NA = n × sin θ”). Therefore, the irradiation width 2d which is the diameter of the irradiation region of the laser beam La in this state with respect to the L2 information layer 14 is 32.8 μm (“2 × (L × tan θ)”). Also, as shown in FIG. 4, when the recorded data recorded in the L1 information layer 12 is reproduced (for example, when tracking the data recording track T12 of the L1 information layer 12), L2 for the L1 information layer 12 is recorded. Due to the eccentricity of the information layer 14, the laser beam La irradiating the data recording track T12 is alternately transmitted through the recorded area A1 of the L2 information layer 14 and the outer peripheral portion thereof. Therefore, as indicated by the alternate long and short dash line in the lower diagram of FIG. 5, when the transmittance adjustment area A2 does not exist around the recorded area A1, the position P23 at which the data recording tracks T12 and T14 intersect in the thickness direction of the optical disk 10 , P24 (see the upper diagrams of FIGS. 4 and 5), the light transmittance of the L2 information layer 14 changes abruptly. This may cause a tracking error for the L1 information layer 12.

  On the other hand, in the recording / reproducing apparatus 1, as shown in the upper diagrams of FIGS. 4 and 5, the absolute value regardless of the direction of the eccentric amount of the L1 information layer 12 with respect to the center O of the optical disc 10 and the eccentric amount of the L2 information layer 14 The total amount E (125 μm) of the absolute value regardless of the direction of the laser beam La, the length (92. A transmittance adjustment region A2 having a width W (100 μm in this example) wider than 2 μm) is formed. For this reason, even in a state where the recorded area A1 does not exist within the irradiation range (irradiation width) of the laser beam La (for example, a state where the laser beam La is irradiated to the position P22 in FIGS. 4 and 5) The transmittance adjustment region A2 exists in a range of about ½ of the irradiation range. In the figure, the irradiation range of the laser beam La applied to the L1 information layer 12 with respect to the L2 information layer 14 is indicated by a broken line. Therefore, a state in which the laser beam La is transmitted through the recorded region A1 of the L2 information layer 14 (for example, a state in which the laser beam La is irradiated to the position P21 in the same figure) is transmitted through the outer peripheral portion of the recorded region A1 ( A sudden change in the light transmittance when shifting to the position P22 in both figures where the laser beam La is irradiated) is avoided. As a result, the occurrence of tracking errors is avoided.

  Further, in a state where the L2 information layer 14 is eccentric with respect to the L1 information layer 12, the optical transmittance of the L2 information layer 14 when the optical disk 10 is rotated and tracked with respect to the data recording track T12, for example, is reduced. The amount of change differs depending on the presence or absence of the transmittance adjustment area A2. Specifically, in a state where the transmittance adjustment area A2 is not formed, the laser beam La irradiated toward the data recording track T12 is alternately transmitted through the recorded area A1 and the unrecorded area A0. Therefore, as shown by the alternate long and short dash line in the lower diagram of FIG. 5, the amount of change in the light transmittance of the L2 information layer 14 per rotation of the optical disk 10 increases. On the other hand, in the state where the transmittance adjustment area A2 having the width W is formed, the laser beam La irradiated toward the data recording track T12 is alternately transmitted through the recorded area A1 and the transmittance adjustment area A2. In this case, as described above, even when the position P22 farthest from the recorded area A1 is transmitted, the transmittance adjustment area A2 exists in the range of about ½ of the irradiation range. . Therefore, as shown by a two-dot chain line in the lower diagram of FIG. 5, the change amount of the light transmittance per one rotation of the optical disk 10 becomes relatively small.

  As described above, according to the data recording method of the recording / reproducing apparatus 1, after recording data on the data recording track in the L2 information layer 14, the light transmittance of the recorded area A1 and the light transmittance of the unrecorded area A0 are recorded. By forming the transmittance adjustment region A2 having a light transmittance intermediate to the transmittance, the laser beam La irradiating the L1 information layer 12 is transmitted through the recorded region A1, and the outer periphery of the recorded region A1. It is possible to avoid a rapid change in light transmittance when transitioning between transmitting states. Therefore, it is possible to avoid the occurrence of a tracking error for the L1 information layer 12. As a result, even if the recording data is not recorded over the entire information layer (L2 information layer 14 in the optical disc 10) on the front side in the irradiation direction of the laser beam La, the information layer (optical disc on the rear side in the irradiation direction). 10 can be accurately accessed, for example, the information layer on the far side in the irradiation direction is a reproduction-only type (the record data is recorded in the information layer on the far side in the irradiation direction). The recording data can be reliably recorded on the information layer on the front side in the irradiation direction without interfering with the tracking on the information layer on the rear side in the irradiation direction even on the two-layer type optical recording medium.

  Further, according to the data recording method by the recording / reproducing apparatus 1, the width along the radial direction of the optical disc 10 in the transmittance adjustment area A2 is the absolute value of the eccentric amount of the L1 information layer 12 and the eccentric amount of the L2 information layer 14. By forming the transmittance adjustment region A2 so as to be wider than the length obtained by subtracting the irradiation width (irradiation width 2d) of the laser beam with respect to the L2 information layer 14 from the total amount E with the absolute value, the L1 information layer 12 The occurrence of tracking errors can be sufficiently avoided. Further, since the difference between the maximum value and the minimum value of the light transmittance per rotation of the optical disk 10 can be reduced, the variation in the reproduction signal at the time of reproducing the recording data recorded on the L1 information layer 12 is reduced. As a result, the occurrence of a reproduction error can be sufficiently avoided.

  Further, according to the data recording method by the recording / reproducing apparatus 1, the transmittance adjustment region A2 is set so that the light transmittance gradually changes in a stepless manner from the recorded region A1 side to the unrecorded region A0 side. By forming, the light transmittance at the boundary between the recorded area A1 and the transmittance adjustment area A2 and the boundary between the transmittance adjustment area A2 and the unrecorded area A0 can be gradually changed. The occurrence of a tracking error for 12 can be avoided more reliably.

  Further, according to the data recording method by the recording / reproducing apparatus 1, the laser beam La having a power smaller than the laser beam La irradiated at the time of recording the recording data and changing the light transmittance of the irradiated portion is not recorded. By continuously irradiating the data recording track to form the transmittance adjustment area A2, it is possible to avoid the occurrence of a tracking error for the L1 information layer 12 while eliminating the need for complicated control for the servo mechanism 3.

  In addition, this invention is not limited to said method and structure. For example, the example in which the transmittance adjustment area A2 is formed over the width W around the recorded area A1 has been described. However, the data recording method in the present invention is not limited to this, and recording of recording data on the L2 information layer 14 is performed. Sometimes, the unrecorded data recording track adjacent to the recorded data recording track (recorded region A1) is irradiated with the laser beam La, for example, around one turn, thereby setting the transmittance adjustment region A2. It can also be formed. By recording the recording data in accordance with this data recording method, the laser beam La passes through the recorded area A1 and the unrecorded area A0 by the transmittance adjustment area A2 for one round of the data recording track formed around the recorded area A1. Since an abrupt change in transmittance at the time of transmission across the substrate can be alleviated, the occurrence of a tracking error can be sufficiently avoided as compared with an optical disc having no transmittance adjustment region A2.

  Further, the example in which the transmittance adjustment area A2 is formed on the outer circumference of the recorded area A1 has been described. However, when recording data is recorded from the outer circumference side of the L2 information layer 14, the inner side of the recorded area A1 is recorded. By forming the transmittance adjustment region A2, the same effect as in the above example can be obtained. Furthermore, although the example in which the transmittance adjustment area A2 is formed around the recorded area A1 after the recording of the recording data on the L2 information layer 14 has been described, the data recording method according to the present invention is not limited to this. For example, prior to the start of recording of recording data on the L2 information layer 14, an unrecorded data recording track is irradiated with a laser beam La to form a transmittance adjustment region A2, and adjacent to the formed transmittance adjustment region A2. It is also possible to start recording of recording data from any one of the data recording track and the data recording track located in the vicinity of the transmittance adjustment area A2. According to this recording method, even in the vicinity of the recording start portion of the recording data for the L2 information layer 14, the laser beam La irradiating the L1 information layer 12 is transmitted through the recorded area A1, and the recorded area A1. A sudden change in the light transmittance can be avoided when transitioning between a state where the light is transmitted through the outside of the light source. As a result, it is possible to avoid occurrence of a tracking error for the L1 information layer 12.

  Further, the example in which the transmittance adjustment region A2 is formed by continuously irradiating the unrecorded data recording track of the L2 information layer 14 with the laser beam La having a power smaller than that at the time of recording the recording data has been described. , A laser beam having a power capable of changing the light transmittance of the irradiated portion (for example, a laser beam La irradiated when recording data is recorded) to irradiate a recording mark for adjusting the transmittance (almost same as a recording mark corresponding to the recording data). Equivalent recording marks) can be recorded on unrecorded data recording tracks to form the transmittance adjustment area A2. According to this recording method, the light transmittance is intermediate between the light transmittance of the recorded area A1 and the light transmittance of the unrecorded area A0 due to the presence of the recording mark recorded on the data recording track. Since the adjustment region A2 is formed, it is possible to sufficiently avoid the occurrence of a tracking error similarly to the configuration in which the laser beam La is continuously irradiated to form the transmittance adjustment region A2. For the recording mark for adjusting the transmittance, a laser beam having a slightly lower power or a slightly higher power than the laser beam La irradiated at the time of recording the recording data is adjusted by adjusting the recording mark formation interval. It can also be formed by irradiation.

  In the data recording method in which the transmittance adjustment area A2 is formed by the transmittance adjustment recording mark, the following recording method can be used to gradually change the light transmittance in the transmittance adjustment area A2. For example, as shown in FIG. 6, the light transmittance can be gradually changed by gradually increasing the distance between the recording mark for adjusting the transmittance (shown in black in the figure) and the recording mark. As shown in FIG. 7, a data recording track in which a recording mark for transmittance adjustment is formed is provided across a data recording track in which a recording mark for transmittance adjustment is not formed, and data in which the recording mark is not formed. The light transmittance can be gradually changed by gradually increasing the number of recording tracks. In this case, when the transmittance adjustment region A2 is formed by forming the transmittance adjustment recording mark across the data recording track on which the transmittance adjustment recording mark is not formed, the transmittance adjustment recording is first performed. The distance from the data recording track on which the mark is formed to the data recording track on which the recording mark for adjusting the transmittance is finally formed corresponds to the width of the transmittance adjusting area A2.

  Further, although an example in which the power of the laser beam La is gradually reduced steplessly to form the transmittance adjustment region A2 has been described, the present invention is not limited to this, and the power of the laser beam La is increased stepwise (multiple By gradually irradiating the light (in the stage, when the transmittance adjustment area A2 is formed on the unrecorded data recording track prior to the start of recording of the recording data, “increase gradually”), the light is irradiated. A plurality of transmittance adjustment regions A2, A2,... Having different transmittances can be formed as the transmittance adjustment region in the present invention. Further, the example in which the recording data is recorded on the L1 information layer 12 and the L2 information layer 14 having the spiral data recording track has been described, but also for the optical recording medium having a plurality of concentric data recording tracks. The recording data can be recorded in accordance with the data recording method according to the present invention. Furthermore, although the example which records recording data on the optical disk 10 which has two information layers of L1 information layer 12 and L2 information layer 14 was demonstrated, the optical recording medium which records recording data is not limited to this, An optical recording medium having three or more information layers is also included. Also included are various optical recording media such as an optical recording medium in which one or both of the information layers 12 and 14 are formed of a rewritable information layer, and an optical information recording medium in which the L1 information layer 12 is a read-only type. It is.

2 is a block diagram showing a configuration of a recording / reproducing apparatus 1. FIG. 2 is a cross-sectional view of the optical disc 10. FIG. 4 is a conceptual diagram showing the relationship between an L1 information layer 12 and an L2 information layer 14 of an optical disc 10, and a laser beam La and reflected light Lb. 4 is a conceptual diagram illustrating an example of an eccentric state and a recording state of an L1 information layer 12 and an L2 information layer 14 with respect to the center O of the optical disc 10. FIG. It is explanatory drawing explaining the relationship between the data recording track | truck T12 of the L1 information layer 12, the data recording track | truck T14 of the L2 information layer 14, and the transmittance | permeability adjustment area | region A2. It is a top view which shows an example of the optical disk 10 in which the transmittance | permeability adjustment area | region A2 was formed with the recording mark for transmittance | permeability adjustment. It is a top view which shows another example of the optical disk 10 in which the transmittance | permeability adjustment area | region A2 was formed with the recording mark for transmittance | permeability adjustment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording / reproducing apparatus 4 Pickup 5 Controller 10 Optical disk 12 L1 information layer 14 L2 information layer A0 Unrecorded area A1 Recorded area A2 Transmittance adjustment area 2d Irradiation width E Total amount E2, E4 Eccentric amount L Distance La Laser beam Lb Reflected light W width

Claims (8)

When recording the recording data on the optical recording medium by irradiating the optical recording medium on which the information layer of the N layer (N is a natural number of 2 or more) is formed with a laser beam,
After the recording data is recorded on the data recording track in the M-th information layer (M is a natural number equal to or less than (N−1)) from the incident surface side of the laser beam, the recording data is adjacent to the recorded data recording track. By irradiating the laser beam to any one of the unrecorded data recording track and the unrecorded data recording track located in the vicinity of the recorded data recording track, the recorded data A transmittance adjustment region having a light transmittance intermediate between the light transmittance of the recorded area including the data recording track and the light transmittance of the unrecorded area including the unrecorded data recording track is formed. Data recording method.   The data recording method according to claim 1, wherein the transmittance adjustment region is formed by irradiating at least one of the unrecorded data recording tracks with the laser beam.   The width in the radial direction of the optical recording medium in the transmittance adjustment region is such that the amount of eccentricity of the Mth information layer relative to the center of the optical recording medium and the (M + 1) th information layer from the incident surface side. From the total amount of the eccentricity with respect to the center of the optical recording medium, the length obtained by subtracting the width of irradiation of the M-th information layer by the laser beam irradiated when tracking the (M + 1) -th information layer The data recording method according to claim 1, wherein the transmittance adjustment region is formed so that the width is also wide.   Prior to the start of recording of the recording data on the Mth information layer, the transmittance adjustment region is formed by irradiating the unrecorded data recording track with the laser beam, and adjacent to the formed transmittance adjustment region. 4. The recording of the recording data is started from any one of an unrecorded data recording track and an unrecorded data recording track located in the vicinity of the transmittance adjustment area. The data recording method according to claim 1.   From the recorded region side toward the unrecorded region side so that the light transmittance gradually changes from the light transmittance of the recorded region to the light transmittance of the unrecorded region in multiple steps or steplessly. The data recording method according to claim 1, wherein the transmittance adjustment region is formed.   2. The transmittance adjustment region is formed by continuously irradiating a laser beam having a power smaller than that of the laser beam irradiated at the time of recording the recording data and capable of changing the light transmittance of the irradiated portion. 6. The data recording method according to any one of items 1 to 5.   6. The data according to claim 1, wherein the transmittance adjustment region is formed by irradiating a laser beam having a power capable of changing the light transmittance of the irradiated portion to record a recording mark for transmittance adjustment. Recording method. A pickup that irradiates a laser beam onto an optical recording medium on which an information layer of N layers (N is a natural number of 2 or more) is formed, and recording data is recorded on the optical recording medium by controlling the irradiation of the laser beam by the pickup. And a control unit that
The controller irradiates the laser beam from the pickup toward the data recording track in the Mth information layer (M is a natural number equal to or less than (N-1)) from the incident surface side of the laser beam. After recording data, an unrecorded data recording track adjacent to the recorded data recording track, and an unrecorded data recording track located near the recorded data recording track By irradiating any one of the above, the light transmittance of the recorded area including the recorded data recording track and the light transmission of the unrecorded area including the unrecorded data recording track A recording apparatus for forming a transmittance adjustment region having a light transmittance intermediate to the transmittance.

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