WO2014049710A1

WO2014049710A1 - Recording medium, recording reproduction device and method

Info

Publication number: WO2014049710A1
Application number: PCT/JP2012/074691
Authority: WO
Inventors: 吉田　昌義; 琢也白戸
Original assignee: パイオニア株式会社; パイオニアデジタルデザインアンドマニュファクチャリング株式会社
Priority date: 2012-09-26
Filing date: 2012-09-26
Publication date: 2014-04-03

Abstract

A recording medium (11) in CLV format includes a guide layer (12) in which guide tracks (TR) have been formed preliminarily, and a plurality of recording layer (13). In the guide tracks, a plurality of mark groups (MG) are arranged, each of which includes a plurality of identical recording marks formed at identical rotation phase positions in a plurality of tracks that are adjacent to each other in the radial direction. The plurality of mark groups are arranged discretely along the track direction in such a manner that at most one center mark contained in each of the mark groups is arranged in each of groups each of which is composed of a predetermined number of slots that are arrayed sequentially in the track direction. The mark groups are arranged so as to be deviated from one another in at least one of the radial direction and the track direction so that the mark groups should not be adjacent to one another in the radial direction.

Description

Recording medium, recording / reproducing apparatus and method

The present invention relates to a technical field of a recording medium such as an optical disc having a plurality of recording layers, and a recording / reproducing apparatus and method for performing at least one of a recording process and a reproducing process for the recording medium.

As a recording medium provided with a plurality of recording layers, for example, a recording medium having a plurality of recording layers that are actual targets of at least one of recording processing and reproducing processing, and a guide layer on which guide tracks used for tracking control are formed ( For example, a so-called guide layer separation type optical disc is known (see Patent Document 1 to Patent Document 3). A recording / reproducing apparatus that performs at least one of recording processing and reproducing processing on such a recording medium is configured to perform guide laser light for reading the guide track of the guide layer and at least one of recording processing and reproducing processing on the recording layer. The recording / reproducing laser beam is irradiated. The recording / reproducing apparatus performs at least one of the recording process and the reproducing process by irradiating the recording layer with the recording / reproducing laser beam while performing tracking control based on the push-pull signal obtained from the return light of the guide laser beam.

JP-A-4-301226 JP 2003-67939 A International Publication WO2009 / 037773 Pamphlet

However, in general, the diameter of the beam spot formed by the guide laser beam on the guide layer is different from the diameter of the beam spot formed by the recording / reproducing laser beam on the recording layer. In accordance with the difference in the diameter of the beam spot, the track pitch of the recording layer (that is, the track pitch of the information track composed of the recording marks on the recording layer) is the track pitch of the guide layer (that is, the guide track). As an example, a technique for realizing high-density recording in the recording layer by making the size smaller than the track pit) can be considered. However, considering that the tracking control in the recording layer is substantially performed based on the return light of the guide laser light irradiated to the guide layer, the tracking control accuracy in the recording layer is the tracking in the guide layer. Depends on control accuracy. As a result, when the track pitch of the recording layer is made smaller than the track pitch of the guide layer, the tracking control accuracy actually realized in the recording layer can be calculated from the beam spot diameter of the recording / reproducing laser beam. It becomes coarser than the accuracy of control.

On the other hand, a method for realizing high-density recording in the recording layer by making the track pitch of the guide layer and the track pitch of the recording layer substantially equal is considered as an example. However, in this case, the guide laser light irradiates a plurality of guide tracks of the guide layer at a time. As a result, there is a technical problem that it becomes extremely difficult to make the guide laser beam follow the target guide track.

In particular, when the CLV (Constant Linear Velocity) method is employed, it is extremely difficult to increase the utilization efficiency on the disk surface and achieve high-density recording. Also, the address configuration method of the guide layer is not disclosed.

The present invention has been made in view of the above-described problems, for example, and a recording medium capable of performing high-precision tracking control while adopting the CLV method, and recording processing and reproducing processing for such a recording medium. It is an object to provide a recording / reproducing apparatus and method for performing at least one of the above.

In order to solve the above-described problem, the recording medium of the present invention is a CLV recording medium, in which guide tracks that are partitioned by a plurality of slots arranged in the track direction are formed in advance, and the guide layer A plurality of recording layers stacked on top of each other, and the guide track is formed at the same rotational phase position of a plurality of guide tracks adjacent to each other along a radial direction intersecting the track direction and is a unit of the slot. A plurality of mark groups including the same plurality of recording marks formed together are arranged, and each of the plurality of slots includes a predetermined number of slots arranged continuously along the track direction. A maximum of one central mark located at the center along the radial direction among a plurality of recording marks included in each of the plurality of mark groups is arranged. Thus, the plurality of mark groups are discretely arranged along the track direction, and the plurality of mark groups are at least in the radial direction and the track direction so as not to be adjacent to each other along the radial direction. They are shifted along one side.

In order to solve the above-described problems, the recording / reproducing apparatus of the present invention is a recording / reproducing apparatus that performs at least one of the recording process and the reproducing process on the recording medium of the present invention described above, and a guide laser beam is applied to the guide layer. Light irradiation means for irradiating and condensing and irradiating and condensing one recording layer of the plurality of recording layers with a recording / reproducing laser beam different from the guide laser beam, and the guide laser from the guide layer A first control unit that controls the light irradiation unit to perform tracking control that applies tracking servo to the guide track in a predetermined band based on the return light of the light, and the tracking servo is applied. Irradiating and condensing the recording / reproducing laser beam on the one recording layer, thereby performing at least one of the recording process and the reproducing process. And a second control means for controlling the light irradiating means Migihitsuji.

In order to solve the above-described problems, the recording / reproducing method of the present invention irradiates and condenses the guide layer with the guide laser beam on the above-described recording medium of the present invention (including various aspects thereof). Recording that performs at least one of a recording process and a reproducing process using a light irradiation unit that irradiates and condenses a recording / reproducing laser beam different from the guide laser beam to one of the plurality of recording layers. In the reproducing method, the light irradiation unit is controlled to perform tracking control for applying tracking servo to the guide track in a predetermined band based on the return light of the guide laser light from the guide layer. With the control process and the tracking servo being applied, the recording process is performed by irradiating and condensing the one recording layer with the recording / reproducing laser beam. Serial and a second controlling process of controlling the light emitting means to perform at least one of the reproduction process.

The operation and gain of the present invention will be clarified from the embodiments described below.

It is a typical perspective view which makes each layer easy to see by disassembling a plurality of layers constituting one optical disk at intervals in the stacking direction (vertical direction in FIG. 1). It is sectional drawing which shows the cross section of an optical disk with the irradiation aspect of a guide laser beam and a recording / reproducing laser beam. It is a partially expanded perspective view of the guide layer in an Example. It is a partially expanded perspective view of the same meaning as FIG. 3 in the comparative example of an Example. FIG. 4 is a partially enlarged perspective view having the same concept as in FIG. 3 when an example of prepits is provided in the embodiment. FIG. 4 is a partially enlarged perspective view having the same concept as in FIG. 3 in the case where another example of the pre-pit is provided in the embodiment. It is a typical partial enlarged plan view showing a guide track for low density recording. It is a typical partial enlarged plan view showing a guide track for high density recording. It is a top view which shows the arrangement | positioning aspect of the mark group in a guide layer in an Example. It is a typical expansion perspective view which shows the physical structure of the mark group in an Example. It is a block diagram of the recording / reproducing apparatus in an Example. 6 is a flowchart of a recording / reproducing method in the embodiment. 6 is a flowchart of a recording method for a new disk in the embodiment. 5 is a flowchart illustrating an example of a playback method for a new disc in the embodiment. It is a flowchart which shows the other example of the reproducing method with respect to a new disc in an Example. It is a block diagram of the circuit part which performs tracking control among the recording / reproducing apparatuses of an Example. FIG. 17 is a characteristic diagram showing an operation of sampling a tracking error of a sampler included in the circuit part of FIG. In an Example, it is a characteristic view which shows the phase rotation which prescribes | regulates the arrangement | positioning space | interval of the two mark groups which adjoin each other along a track | truck. FIG. 6 is a characteristic diagram illustrating a frequency characteristic of a gain in a tracking servo that defines an arrangement interval between two mark groups adjacent to each other along a track in an embodiment. It is a typical enlarged plan view which shows the physical structure of the mark group in an Example. It is a typical enlarged plan view which shows the physical structure of the mark group in another modification. It is a typical enlarged plan view which shows the physical structure of the mark group in another modification. It is a typical enlarged plan view which shows the physical structure of the mark group in another modification. It is a typical perspective view of the same meaning as FIG. 1 of the optical disk in another modification.

Hereinafter, as a best mode for carrying out the invention, a recording medium, and a recording / reproducing apparatus and method according to embodiments will be described in order.
(Embodiment of recording medium)
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In order to solve the above-described problem, the recording medium of the present embodiment is a CLV recording medium, and includes a guide layer in which guide tracks divided by a plurality of slots arranged in the track direction are formed in advance, and the guide A plurality of recording layers stacked on a layer, and the guide track is formed at the same rotational phase position of a plurality of guide tracks adjacent to each other along a radial direction intersecting the track direction, and the unit of the slot A plurality of mark groups including the same plurality of recording marks formed in accordance with the predetermined number of slots arranged in a row along the track direction among the plurality of slots. In addition, a maximum of one central mark located at the center along the radial direction among a plurality of recording marks included in each of the plurality of mark groups is arranged. As described above, the plurality of mark groups are discretely arranged along the track direction, and the plurality of mark groups are arranged in the radial direction and the track direction so as not to be adjacent to each other along the radial direction. It is shifted along at least one side.

The recording medium of the present embodiment includes a guide layer and a plurality of recording layers. In the guide layer, guide tracks (for example, groove tracks, land tracks, etc.) used for tracking control are formed. Therefore, the recording / reproducing apparatus that performs at least one of the recording process and the reproducing process on the recording medium (more specifically, on a plurality of recording layers included in the recording medium) irradiates the guide layer. Based on the return light of the guide laser light (that is, the guide laser light reflected by the guide layer), a push-pull signal corresponding to the positional relationship between the guide track and the beam spot of the guide laser light can be acquired. As a result, the recording / reproducing apparatus can perform tracking control based on the push-pull signal. Further, the recording / reproducing apparatus identifies address position on the guide track (in other words, position on the recording layer associated with the position on the guide track) based on the return light of the guide laser beam. Etc. can be obtained. Furthermore, the recording / reproducing apparatus can acquire arbitrary control information other than the address information based on the return light of the guide laser beam. As a result, the recording / reproducing apparatus can determine the irradiation position of the guide laser beam or the recording / reproducing laser beam based on the address information. Therefore, the recording / reproducing apparatus performs recording and reproduction processing conforming to the CLV (Constant Linear Velocity) method for a desired position of a desired recording layer among a plurality of recording layers while performing such tracking control. At least one of the following can be performed.

In the following, for simplification of description, not only the operation of causing the guide laser beam to follow the guide track, but also the operation of irradiating the guide laser beam and the recording / reproducing laser beam to the desired position determined from the address information. Will be collectively referred to as “tracking control”.

Here, the “guide layer” typically refers to a position in the recording surface of each recording layer (that is, a radial position and track along the recording surface) when recording processing is performed on at least each recording layer. It means a layer irradiated with guide laser light (in other words, guiding or guiding the guide laser light) in order to make the recording / reproducing apparatus recognize the (direction position). The “guide layer” typically has a physical guide track for generating a tracking error signal (or a wobble signal, a pre-pit signal, etc., which is the source of the tracking error signal) and address information in advance. It is a layer built in.

Further, the “guide track” means a trajectory that the guide laser beam follows when a recording process is performed on at least each recording layer and is physically formed in advance on the guide layer. The guide track may be, for example, a wobbled track or a non-wobbled track (that is, a straight structure track). Furthermore, the guide track may be a track in which pits are formed, or may be a track in which pits are not formed. Note that the information track formed on the recording layer after the recording process is performed on the recording layer is formed afterwards as an array of newly recorded recording marks on the recording layer in which no track originally existed. The track is clearly distinguished from the “guide track” formed in advance on the guide layer.

Also, the guide track is divided by a plurality of slots arranged along the track direction (that is, the direction in which the guide track extends, typically the circumferential direction of a disk-shaped recording medium). A “slot” is a logical or physical section in which a guide track is partitioned in the track direction. The plurality of slots that divide such guide tracks may typically be continuously arranged without gaps or adjacent to each other in the track direction. Similarly, the plurality of slots may be continuously arranged without gaps or adjacent to each other in the radial direction (that is, the direction intersecting or orthogonal to the track direction). However, the plurality of slots may be arranged so that a slight gap is secured between two slots adjacent to each other along the track direction. Similarly, the plurality of slots may be arranged so that a slight gap is secured between two slots adjacent to each other along the radial direction.

It is preferable that each of the plurality of recording layers can record data independently of the other recording layers. Similarly, each of the plurality of recording layers is preferably capable of reproducing data independently of the other recording layers. Here, each of the plurality of recording layers preferably has a relatively simple structure (for example, a straight groove structure, a straight land structure, or a mirror structure) in an unrecorded state in which no data is recorded. This is because it is preferable from the viewpoint of manufacturing the recording medium that the alignment between the plurality of recording layers and the alignment with the guide layer are almost or absolutely unnecessary. The structure of the recording layer is such that, when viewed from the irradiation side of the recording / reproducing laser beam, the transmittance and reflectance of each recording layer so that the recording / reproducing laser beam reaches the recording layer or guide layer on the back side. Can be recorded by various recording methods set to fall within a predetermined range.

More specifically, when the recording process is performed, for example, guide laser light irradiated on a guide track formed on the guide layer (for example, red that forms a beam spot with a relatively large diameter). A tracking error signal, address information, and the like are detected from the return light of the laser beam. Tracking control is performed based on the tracking error signal detected in this way. Under such tracking control, a recording / reproducing laser beam (for example, a blue laser that forms a beam spot having a relatively small diameter) at a desired position of a desired recording layer based on address information or the like. Light) is collected. As a result, a data recording process for a desired position of a desired recording layer is performed. In other words, with reference to the position of the guide track formed in advance in the guide layer, the recording / reproducing laser beam irradiation position (that is, data) in a desired recording layer in which no track exists (for example, in a mirror state) (Recording position) is positioned.

Here, if the optical system for irradiating the guide laser beam and the recording / reproducing laser beam is fixed, the positional relationship between the beam spot of the guide laser beam and the beam spot of the recording / reproducing laser beam is also fixed. For this reason, tracking control is performed so as to adjust the irradiation position of the guide laser beam on the guide layer. Tracking control is performed so as to adjust the irradiation position of the recording / reproducing laser beam on the desired recording layer. I can say that. In other words, by using the return light of the guide laser light irradiated to the guide track formed in advance, the tracking control of the recording / reproducing laser light in the recording surface of the desired recording layer where the track is not formed in advance is performed. .

On the other hand, when the reproduction process is performed, tracking control may be performed in the same manner as when the recording process is performed. That is, the tracking control of the recording / reproducing laser beam in the recording surface of the desired recording layer may be performed using the return light of the guide laser beam irradiated to the guide track formed in advance. Alternatively, when the reproduction process is performed, an information track is formed on the desired recording layer afterwards. Therefore, the recording surface of the desired recording layer is based on the return light of the recording / reproducing laser beam irradiated on the information track formed afterwards instead of the guide laser beam irradiated on the previously formed guide track. Tracking control of the recording / reproducing laser beam may be performed.

A plurality of mark groups are arranged on the guide track. Each of the plurality of mark groups includes the same plurality of recording marks formed at the same rotational phase position of a plurality of tracks adjacent in the radial direction. For example, as an example, the guide track includes a first mark group including the same three first recording marks formed at positions where the rotational phase positions of three adjacent first guide tracks are 0 degrees. , And the second mark group including a plurality of the same second recording marks formed at positions where the rotational phase positions of three adjacent second guide tracks are 10 degrees.

As long as the radial position is different, different mark groups may be arranged at the same rotational phase position. For example, as an example, the guide track has a plurality of identical first recording marks formed at positions where the rotational phase positions of three adjacent first guide tracks whose radial positions are 23 mm are 0 degrees. And a plurality of identical second recording marks formed at positions where the rotational phase positions of three adjacent second guide tracks having a radial position of 25 mm are 0 degrees. The 2nd mark group containing may be arrange | positioned.

The plurality of recording marks included in each of the plurality of mark groups are formed according to the slot unit. For example, each of the plurality of mark groups includes the same plurality of recording marks formed in a one-to-one relationship in a plurality of slots arranged along the radial direction. As a result, it can be said that each of the plurality of mark groups is also arranged in accordance with the slot unit.

Each of the plurality of mark groups formed on the guide layer is a mark group for causing the guide laser beam to follow, and may typically be a mark group for optically generating a tracking error signal. . Alternatively, each of the plurality of mark groups formed on the guide layer is a mark group for identifying a position on the guide layer (in other words, a position on the recording layer corresponding to the position on the guide layer). Specifically, it may be a mark group for optically generating address information and the like. Each of the plurality of recording marks constituting each of the plurality of mark groups may be realized by a physical structure on the guide track. As such a physical structure, for example, a combination of a wobble and a prepit structure (for example, a land prepit or a groove prepit) formed inside or outside a guide track side wall, or a wobble and a partially cutout structure It may be realized by a combination, an arrangement or a series of prepits on a surface (for example, a mirror surface) without a groove and a land. Here, the “physical structure” means a physically existing structure, unlike a logical structure or a conceptual or virtual structure constructed by simple data. The physical structure is already formed on the guide track when the recording medium is completed.

Particularly in the present embodiment, the plurality of mark groups are discretely arranged along the track direction along the spiral or concentric guide track (in other words, the tangential direction of the guide track). The “discrete arrangement of the plurality of mark groups in the track direction” in the present embodiment is located at the center in the radial direction among the plurality of recording marks included in each of the plurality of mark groups, as described below. Realized by focusing on the center mark. Focusing on the mark group in which the first recording mark to the Nth recording mark are arranged from the inner circumference side toward the outer circumference side, the “center mark” is (1 + N) / 2nd recording counted from the inner circumference side. Corresponds to the mark.

Specifically, in order to realize a discrete arrangement of a plurality of mark groups in the track direction, each group composed of a predetermined number of slots continuously arranged along the track direction among the plurality of slots is included in each group. A maximum of one center mark included in each of the plurality of mark groups is arranged. That is, different center marks (that is, two or more center marks) included in different mark groups are not simultaneously arranged in each group. In addition, since at most one center mark is arranged in each group, not only a group in which one center mark is arranged but also a group in which no center mark is arranged as a group for dividing the guide track. It can happen. For example, the case where the first mark group, the second mark group, and the third mark group are arranged on the guide track will be described as an example. In this case, the center mark of the plurality of recording marks included in the first mark group is, for example, within the first group (more specifically, of the predetermined number of slots constituting the first group). At least one slot). At this time, the center mark of the plurality of recording marks included in the other mark group (that is, the second and third mark groups) is not arranged in the first group. On the other hand, the center mark of the plurality of recording marks included in the second mark group is, for example, in a second group different from the first group (more specifically, the second group is configured. At least one of a predetermined number of slots). At this time, the center mark of the plurality of recording marks included in the other mark group (that is, the first and third mark groups) is not arranged in the second group. On the other hand, the center mark of the plurality of recording marks included in the third mark group is, for example, in a third group different from the first and second groups (more specifically, the third group At least one of the predetermined number of slots constituting the. On the other hand, the center mark of the plurality of recording marks included in the other mark group (that is, the first and second mark groups) is not arranged in the third group. In this case, the fourth group different from the first group to the third group includes a plurality of recording marks included in the fourth mark group different from the first mark group to the third mark group. The center mark may be arranged. Alternatively, the center mark may not be arranged in the fourth group. By paying attention to the center mark included in each such mark group, a discrete arrangement of the plurality of mark groups in the track direction is realized. In other words, in the present embodiment, it can be said that the discrete arrangement of the plurality of mark groups in the track direction corresponds to the discrete arrangement of the center marks included in each mark group.

In addition, in the present embodiment, in particular, the plurality of mark groups are arranged so as not to be adjacent to each other along the radial direction. In order to realize such a non-adjacent arrangement of a plurality of mark groups along the radial direction, at least two mark groups of the plurality of recording mark groups are arranged so as to be displaced along the radial direction. Also good. That is, at least two mark groups of the plurality of recording mark groups may be arranged so as to have a gap (for example, a gap having a predetermined number of tracks) in the radial direction. In this case, the two mark groups shifted along the radial direction may be arranged at the same rotational phase position. Alternatively, the two mark groups displaced along the radial direction may be arranged at different rotational phase positions. Alternatively, at least two of the plurality of recording mark groups may be arranged so as to be shifted along the track direction. That is, at least two mark groups of the plurality of recording mark groups may be arranged so as to be shifted along the track direction so that the rotational phase positions to be arranged are different from each other. In summary, in the present embodiment, “arrangement of a plurality of mark groups that are not adjacent to each other” refers to an arrangement in which some or all of the plurality of mark groups are shifted from each other along the track direction and a part of the plurality of mark groups or All are realized by any one of the arrangements shifted from each other along the radial direction or a combination of these arrangements. That is, the “arrangement that is not adjacent to each other” in the present embodiment can mean an arrangement that is displaced along at least one of the radial direction and the track direction.

Here, for example, in order to perform tracking control in a predetermined band, it is necessary to read a mark group by irradiating one of the guide tracks with guide laser light. However, as a result of research by the inventors of the present application, it has been found that tracking control in a predetermined band can be executed without forming recording marks used for tracking control continuously in the track direction. For example, the arrangement interval in the track direction of the mark group corresponding to the time interval at which the mark group is detected (in other words, the arrangement interval of the center marks included in the mark group, and the length along the track direction of the group described above. If the mark group is not arranged over the entire area along the guide track, a predetermined band can be obtained. It has been found that tracking control can be performed. In addition, even if attention is paid to a plurality of guide tracks adjacent to each other in the radial direction, such mark groups are arranged at a plurality of positions aligned in the radial direction (that is, the same rotational phase position). It has been found that tracking control can be performed in a predetermined band even if it is not (that is, such a group of marks is not regularly arranged in a line in the radial direction).

Therefore, in the present embodiment, as described above, the plurality of mark groups are discretely arranged along the track direction. In particular, in the present embodiment, in order to realize a discrete arrangement of a plurality of mark groups in the track direction, an arrangement interval between center marks included in each mark group (for example, the length of the group in the track direction described above). ) Is preferably set to a preset predetermined distance or less. Here, the “predetermined distance” is typically the longest distance at which tracking control can be performed in a predetermined band (for example, the frequency at which tracking control can be stably performed in a predetermined band). In other words, the distance is shorter than the longest distance at which tracking error signals and address information can be generated continuously or continuously. Further, the “predetermined bandwidth” is a unique bandwidth determined in relation to a bandwidth used when recording processing is performed, and a unique bandwidth for a data format (or data standard) for which tracking control is performed. Means.

For such a predetermined distance, a limit distance capable of performing tracking control in a predetermined band with respect to the guide layer is obtained in advance, experimentally, empirically, or by simulation, and an appropriate margin is determined. And may be set. If a plurality of mark groups (particularly, a plurality of center marks included in the plurality of mark groups) are discretely arranged at an arrangement interval (ie, arrangement pitch) longer than a predetermined distance, for example, in a predetermined band. There is a possibility that the tracking error signal, the address information, and the like cannot be generated as frequently as stable tracking control can be performed. As a result, tracking control cannot be stably performed in a predetermined band.

According to the recording medium of the present embodiment described above, the plurality of mark groups are arranged discretely along the track direction and not adjacent to each other along the radial direction. For this reason, even when the density of the guide tracks is increased until the beam spot of the guide laser beam straddles a plurality of adjacent guide tracks (for example, straddles five guide tracks), it occurs when reading one mark group. Crosstalk due to other mark groups obtained is reduced. Therefore, each mark group can be suitably read using the guide laser beam (that is, a tracking error signal, address information, etc. indicated by each mark group can be suitably acquired). That is, even when the guide laser beam is simultaneously irradiated to a plurality of adjacent guide tracks in the guide layer by making the track pitch of the guide track smaller than the beam spot diameter of the guide laser beam, the guide laser beam Each mark group can be suitably read using. That is, stable tracking control in a predetermined band can be performed.

Such an effect is that the diameter of the beam spot on the guide layer of the guide laser beam (for example, red laser beam) is large and the beam spot on the desired recording layer of the recording / reproducing laser beam (for example, blue laser beam) is large. Under the circumstances, it is particularly advantageous when the recording density for a desired recording layer is increased by effectively utilizing a relatively small beam spot of the recording / reproducing laser beam. Specifically, for example, when a guide track having a relatively small track pitch corresponding to a subsequent information track in the recording layer is formed in advance in the guide layer, it is inevitably in proportion to the track pitch of the guide track. A beam spot of a guide laser beam that forms a large beam spot is simultaneously irradiated over a plurality of guide tracks. Therefore, it is particularly advantageous in that tracking control corresponding to information tracks having a relatively small track pitch on the recording layer can be performed using guide laser light that forms a relatively large beam spot.

Even when the beam spot of the guide laser beam on the guide layer is smaller than the beam spot on the desired recording layer of the recording / reproducing laser beam, or when these beam spots are almost or exactly the same, the track of the guide track As long as the tracking control is performed using the guide laser beam that forms a large beam spot with respect to the pitch, the unique configuration in the present embodiment as described above has a corresponding effect.

In addition, in the present embodiment, since the recording medium adopts the CLV method, the angular velocity on the inner peripheral side of the recording medium is larger than the angular velocity on the outer peripheral side of the recording medium. For this reason, unless special measures are taken, it is difficult or impossible to align a group of marks having a specific length in a radial direction across a plurality of guide tracks, unlike, for example, the CAV (Constant Angular Velocity) method. It is. Then, if no countermeasures are taken in the CLV method, when the guide laser beam forms a beam spot extending over a plurality of guide tracks, the track portion entering the beam spot is tracked according to the radial position. It will shift in the direction. As a result, the reading of the mark group (that is, acquisition of the tracking error signal and address information) must be extremely unstable depending on the radial position. However, in the present embodiment, the plurality of mark groups are arranged not to be adjacent to each other along the radial direction consciously or positively as described above. For this reason, tracking control can be stably performed in a predetermined band in accordance with a high-density track pitch and recording linear density for realizing high-density recording regardless of the radial position. In other words, on the premise of the CLV method, the arrangement positions of a plurality of mark groups (for example, discrete arrangement positions in the track direction, arrangement positions in the radial direction, etc.) in advance according to the radial position are determined. If defined, no technical problem occurs even in the CLV system.

In addition, according to the present embodiment, the center marks included in the plurality of mark groups are arranged one by one for each group including a predetermined number of slots arranged continuously along the track direction. For this reason, in the guide layer, a physical structure for constituting the center mark and other recording marks that constitute the mark group together with the center mark is formed only in a part of the slots secured in accordance with the group. It's enough. That is, in the present embodiment, the physical structure for configuring the center mark and other recording marks that constitute the mark group together with the center mark may not be continuously formed over the entire area of the guide track. Moreover, since the presence / absence of the slot (for example, the difference between the slot and the mirror surface) is easily clearly distinguished and easily detected, the mark group can be easily read and stably executed. This is very advantageous in practice.

On the other hand, for a plurality of slots in the recording layer, unlike the guide layer, recording marks constituting user data may be formed in all the continuous slots in both the track direction and the radial direction. Since any slot in the recording layer can be associated with a slot in which the mark group in the guide layer is arranged (in other words, a slot in which the recording mark constituting the mark group is arranged), it is indirect to the recording layer. In addition, tracking control can be performed in a predetermined band.

In addition, in the present embodiment, each mark group includes the same plurality of recording marks formed at the same rotational phase position. Therefore, the recording / reproducing apparatus preferably reads the mark group without being affected by the deviation (so-called defocus) of the focus offset of the guide laser beam (in other words, obtained from a plurality of recording marks included in the mark group). Tracking error signal, address information, etc. can be acquired).

As a result, while adopting the CLV method, the track pitch and recording linear density (for example, linear recording density, pit pitch or information transfer speed (that is, recording linear density × movement speed)) that can be recorded or reproduced in the recording layer are It is possible to increase the level to what can be said to be “high density recording”, which is the original purpose of a multilayer information recording medium.

In the above description, an example in which both the tracking error signal and the address information (or other arbitrary control information, the same applies hereinafter) is acquired from a plurality of mark groups is described. However, while either one of the tracking error signal and the address information is acquired from the plurality of mark groups, either the tracking error signal or the address information may not be acquired. For example, when the guide track has a land / groove structure (that is, the guide track is composed of a groove track and a land track), the tracking error signal follows components other than the mark group (that is, the guide track). It can be obtained from the return light of the guide laser beam. Therefore, in this case, the tracking error signal does not have to be acquired while the address information is acquired from the plurality of mark groups. However, even in this case, a plurality of mark groups are in the track direction to such an extent that address information (or arbitrary control information) acquired from the mark group can be acquired in a predetermined band (in other words, a predetermined period). It is preferable to arrange | position discretely along. For example, when a recording clock is generated from a plurality of mark groups, the arrangement interval between the center marks included in each mark group (for example, the length in the track direction of the group described above) is the generation of the recording clock. It is preferable that the distance is set to a predetermined distance or a distance less than the predetermined distance.

<2>
In another aspect of the recording medium of the present embodiment, each of the plurality of mark groups is (i) arranged in front of the plurality of recording marks included in each of the mark groups and along the track direction. A plurality of front buffer regions having different lengths, and (ii) a plurality of front buffer regions arranged behind the plurality of recording marks included in the respective mark groups and having different lengths along the track direction. The plurality of front buffer areas and the plurality of rear buffer areas are arranged such that the plurality of recording marks included in the mark group sandwiched therebetween have the same rotational phase. It has such a length that it is formed at a position.

According to this aspect, by adjusting the lengths of the plurality of front buffer areas and the plurality of rear buffer areas in the track direction, the positions in the track direction of the plurality of recording marks included in each mark group are aligned (that is, A plurality of recording marks included in each mark group can be formed at the same rotational phase position). Therefore, even when the end portions of the slots between the plurality of guide tracks adjacent in the radial direction are shifted in the track direction due to the adoption of the CLV method, A plurality of mark groups each including a mark can be suitably arranged on the guide layer. In other words, the influence of the positional displacement of the slots between the plurality of guide tracks adjacent in the radial direction due to the adoption of the CLV method is the length in the track direction of each of the plurality of front buffer areas and the plurality of rear buffer areas. It can be absorbed by adjusting the thickness.

In addition, since buffer areas are provided before and after each mark group in the track direction, it is easy to find the mark group along the guide track. As a result, the mark group can be read stably and reliably.

<3>
In the aspect of the recording medium in which each mark group is sandwiched between a plurality of front buffer areas and a plurality of rear buffer areas as described above, the plurality of mark groups include one recording mark and a front of the one recording mark. One front buffer area and one rear buffer area arranged behind the one recording mark are arranged so as to be arranged in one slot.

According to this aspect, even if each mark group is sandwiched between a plurality of front buffer areas and a plurality of rear buffer areas, the plurality of recording marks constituting each mark group and the plurality of front buffer areas And a plurality of rear buffer regions can be formed in accordance with the slot unit.
<4>
In another aspect of the recording medium of the present embodiment, the length in the track direction of each of the plurality of slots and the unit in the track direction of the format unit of the data to be recorded in the plurality of recording layers, respectively. The track is divided into the plurality of slots so that the length is a predetermined integer ratio.

With this configuration, the length in the track direction of the slot in the guide layer and the length in the track direction of the structural unit of the user data format to be recorded in each recording layer have a predetermined integer ratio. . Here, the “format unit” is a unit conforming to the data format (for example, an error correction unit represented by an ECC (Error Correction Code) block, an ADIP (Address In Pre-groove) unit, or the like). ). The structural unit of such a format is typically a unit that is handled when a predetermined type of processing is performed during information recording or information reproduction.

For this reason, the relationship between the generation period of the tracking error signal and the address information and the recording period of the data on the recording layer is kept constant regardless of the position in the radial direction or the position in the track direction. be able to. In particular, since the recording medium adopts the CLV method, even when the angular velocity changes depending on the radial position, the tracking control can be stably performed at an arbitrary radial position. Moreover, in order to realize such an effect, it is sufficient to define the length of the slot of the guide layer in the track direction in accordance with the length of the structural unit of the data format when manufacturing the recording medium.

As described above, by employing the slot, a guide operation such as a tracking operation with respect to the recording layer can be performed relatively easily and can be performed extremely stably.
<5>
In another aspect of the recording medium of the present embodiment, the plurality of slots have the same length in the track direction and are arranged in the track direction.

According to this aspect, the slot arrangement rule in the guide layer and the plurality of recording layers can be simplified. In addition, among the plurality of slots in the guide layer, the slot in which the mark group (or the recording mark constituting the mark group) is arranged can be determined relatively easily.

The plurality of slots may be arranged without a gap along the track direction. That is, the plurality of slots may be arranged so that there is no gap between two adjacent slots. Alternatively, the plurality of slots may be arranged while ensuring a slight gap (for example, a gap shorter than the slot length) along the track direction. That is, the plurality of slots may be arranged so that a slight gap (for example, a gap shorter than the length of the slot) is secured between two adjacent slots.
<6>
In another aspect of the recording medium of the present embodiment, each of the plurality of recording marks includes a wobble or a prepit structure.

According to this aspect, each recording mark is composed of a wobble and pre-pit structure associated with the tracking error signal and address information described above. Here, the “wobble and prepit structure” means a structure in which a wobbling guide track is formed and a prepit is formed in the guide track. Further, the “pre-pit” means a convex or concave physical pit or phase pit formed on or in the guide track so as to be narrower than the width of the guide track.

As described above, the guide track is previously constructed in the guide layer as a guide track in which wobbling and pits are formed. Therefore, construction of the guide track is relatively easy, and finally, tracking control with high reliability and stability can be realized.
<7>
In another aspect of the recording medium of the present embodiment, the guide track is a tracking servo guide track, and each of the plurality of mark groups is a mark group for generating the tracking servo tracking signal. The plurality of mark groups are discretely arranged along a track direction at an arrangement interval equal to or less than a distance at which the tracking servo can operate in a predetermined band, and the plurality of mark groups are the tracking servo Based on the beam diameter of the light beam, the light beam is arranged so as not to be adjacent to each other along the radial direction so that the light beam is not simultaneously irradiated.

According to this aspect, even if the density of the guide track is increased until the beam spot of the guide laser beam straddles a plurality of adjacent guide tracks, it is caused by other mark groups that may occur when one mark group is read. Crosstalk is reduced. Therefore, each mark group can be suitably read using the guide laser beam (that is, a tracking error signal or the like indicated by each mark group can be suitably acquired). That is, even when the guide laser beam is simultaneously irradiated to a plurality of adjacent guide tracks in the guide layer by making the track pitch of the guide track smaller than the beam spot diameter of the guide laser beam, the guide laser beam Each mark group can be suitably read using. That is, stable tracking control in a predetermined band can be performed.
<8>
In another aspect of the recording medium of the present embodiment, the plurality of mark groups are mark groups for carrying address information indicating address positions from the inner circumference to the outer circumference or from the outer circumference to the inner circumference along the track direction. is there.

According to this aspect, even if the density of the guide track is increased until the beam spot of the guide laser beam straddles a plurality of adjacent guide tracks, it is caused by other mark groups that may occur when one mark group is read. Crosstalk is reduced. Therefore, each mark group can be suitably read using the guide laser beam (that is, the address information and the like indicated by each mark group can be suitably acquired). That is, even when the guide laser beam is simultaneously irradiated to a plurality of adjacent guide tracks in the guide layer by making the track pitch of the guide track smaller than the beam spot diameter of the guide laser beam, the guide laser beam Each mark group can be suitably read using. That is, stable tracking control in a predetermined band can be performed.
(Embodiment of recording / reproducing apparatus)
<9>
In order to solve the above problems, the recording / reproducing apparatus of the present embodiment is a recording / reproducing apparatus that performs at least one of the recording process and the reproducing process for the recording medium of the present embodiment (including various aspects thereof) described above. Irradiating and condensing the guide layer with guide laser light and condensing and condensing one recording layer of the plurality of recording layers with a recording / reproducing laser light different from the guide laser light And first control means for controlling the light irradiation means to perform tracking control for applying tracking servo to the guide track in a predetermined band based on the return light of the guide laser light from the guide layer. In the state where the tracking servo is applied, the recording and reproducing laser light is irradiated and condensed on the one recording layer, so that the recording process and the previous recording layer are performed. And a second control means for controlling said light emitting means to perform at least one of the reproduction process.

According to the information recording apparatus of the present embodiment, the guide laser light is irradiated and condensed on the guide layer by the light irradiation means that is an optical pickup including, for example, two types of semiconductor lasers. As described above, the guide laser beam may be a laser beam having a relatively large beam spot diameter formed on the guide layer, such as a red laser beam. In other words, the guide laser beam may be a laser beam with a thick light beam that forms a beam spot with a large diameter that is irradiated over a plurality of guide tracks.

Then, return light (for example, reflected light, scattered light, refracted light, transmitted light, etc.) of the guide laser light from the guide layer is received by the light receiving means. Here, the light receiving means is, for example, a light receiving element that is formed integrally with the light irradiating means and at least partially shares an optical system such as an objective lens (for example, a photodetector such as a two- or four-divided CCD (Charged-Coupled Device)) ). For example, the light receiving means may receive return light of guide laser light guided from the guide layer to the light receiving means via a prism, a dichroic mirror, a dichroic prism, or the like.

Subsequently, various information (for example, tracking error signal and address information) indicated by the mark group formed on the guide layer based on the return light of the guide laser light received by the light receiving means is, for example, a processor, an arithmetic circuit, or a logic circuit. Etc. are acquired by information acquisition means including the above.

Subsequently, on the basis of various information acquired by the information acquisition means, the first control means such as a tracking servo circuit, for example, an optical pickup or the like so as to perform tracking control for applying tracking servo to the guide track in a predetermined band. The light irradiation means is controlled. For example, the tracking laser actuator of the light irradiation means is controlled by feedback control or feedforward control, so that the guide laser light follows the guide track. At this time, as described above, in order to perform the tracking control so that the tracking servo is applied in a predetermined band, the mark group does not have to be arranged in all the slots along the guide track. In other words, the slots in which the mark groups are arranged (that is, the recording marks constituting the mark groups are formed) need only be arranged discretely along the track direction according to a predetermined band.

Note that, as described above, either one of the tracking error signal and the address information is acquired from the plurality of mark groups, while either one of the tracking error signal and the address information may not be acquired. For example, when the guide track has a land / groove structure (that is, the guide track is composed of a groove track and a land track), the tracking error signal follows components other than the mark group (that is, the guide track). It can be obtained from the return light of the guide laser beam. Therefore, in this case, the first control step may control the light irradiation unit to perform tracking control based on the address information acquired from the plurality of mark groups and the tracking error signal acquired from the guide track. Good. However, even if both the tracking error signal and the address information are acquired from the plurality of mark groups, and either the tracking error signal and the address information are acquired from the plurality of mark groups, the first The control means does not change tracking control based on the return light of the guide laser light.

In the state where the tracking control is performed in the predetermined band as described above, a recording / reproducing laser beam modulated in accordance with data to be recorded is controlled from the light irradiation unit under the control of the second control unit such as a processor. The desired recording layer is irradiated and condensed. The recording / reproducing laser beam may be a laser beam having a relatively small beam spot diameter formed on a desired recording layer such as a blue laser beam for high-density recording. From the viewpoint of realizing high-density recording, it is desirable that the recording / reproducing laser beam is a thinner light beam.

Then, in the desired recording layer, data is sequentially recorded in an area to be an information track corresponding to the guide track in the guide layer. Alternatively, already recorded data is reproduced in a desired recording layer. At this time, if data recording to the recording layer is performed in units corresponding to the slots, for example, an integral multiple of the slots, the recording process or the reproducing process becomes simple and stable.

As described above, the recording / reproducing apparatus of the present embodiment can suitably record data at a high density on the recording layer of the recording medium of the present embodiment described above. Moreover, the recording / reproducing apparatus of this embodiment can reproduce suitably the data recorded on the recording layer in the recording medium of this embodiment mentioned above.

Incidentally, in response to the various aspects that can be adopted by the recording medium of the present embodiment described above, the recording / reproducing apparatus of the present embodiment can also adopt various aspects.
(Embodiment of recording / reproducing method)
<10>
In order to solve the above-described problem, the information recording method of the present embodiment irradiates the guide layer with guide laser light on the recording medium of the present embodiment described above (including various aspects thereof) and collects the light. And at least one of the recording process and the reproducing process using a light irradiating means for irradiating and condensing one recording layer of the plurality of recording layers with a recording / reproducing laser beam different from the guide laser beam. In the recording / reproducing method to be performed, the light irradiation unit is controlled so as to perform tracking control for applying tracking servo to the guide track in a predetermined band based on the return light of the guide laser light from the guide layer. In the first control step and in the state where the tracking servo is applied, the recording process is performed by irradiating and condensing the recording / reproducing laser beam on the one recording layer. And a second controlling process of controlling the light emitting means to perform at least one of the reproduction process.

According to the recording / reproducing method of the present embodiment, the same effects as the various effects that can be enjoyed by the recording / reproducing apparatus of the present embodiment described above can be suitably enjoyed.

Incidentally, in response to various aspects that can be adopted by the recording / reproducing apparatus of the present embodiment described above, the recording / reproducing method of the present embodiment can also adopt various aspects.

Such an operation and other advantages of the present embodiment will be clarified from examples described below.

As described above, the recording medium of the present embodiment includes a guide layer and a plurality of recording layers, and the center mark included in the mark group is arranged one by one for each group including a predetermined number of slots, and The plurality of mark groups are arranged so as not to be adjacent to each other along the radial direction. The recording / reproducing apparatus of the present embodiment includes light irradiation means, first control means, and second control means. The recording / reproducing method of the present embodiment includes a first control step and a second control step. Therefore, highly accurate tracking control can be performed while employing the CLV method.

Hereinafter, examples will be described with reference to the drawings.

(1) Optical Disc 11 First, the optical disc 11 of this embodiment will be described with reference to FIGS.

(1-1) Configuration of Optical Disc First, the configuration of the optical disc 11 will be described with reference to FIG. 1 and FIG. FIG. 1 is a schematic perspective view in which a plurality of layers constituting one optical disk 11 are disassembled at intervals in the stacking direction (vertical direction in FIG. 1) to make each layer easy to see. FIG. FIG. 2 is a cross-sectional view showing a cross section of the optical disc 11 together with the irradiation modes of the guide laser beam LB1 and the recording / reproducing laser beam LB2.

As shown in FIG. 1, the optical disc 11 includes a single guide layer 12 and a plurality of (that is, two or more) recording layers 13. That is, the optical disk 11 is a so-called guide layer separation type optical disk.

When a recording process on the optical disc 11 (particularly, a recording process on a desired recording layer 13) is performed, the tracking control guide laser beam LB1 focused on the guide layer 12 and each of the plurality of recording layers 13 are recorded. The condensed recording / reproducing laser beam LB2 is irradiated from the recording / reproducing apparatus 101 at the same time. On the other hand, also when a reproduction process for the optical disc 11 (particularly, a reproduction process for a desired recording layer 13) is performed, the guide laser beam LB1 and the recording / reproducing laser beam LB2 are simultaneously irradiated from the recording / reproducing apparatus 101. . However, when the reproducing process is performed on the optical disc 11, the recording / reproducing laser beam LB2 may be used for tracking control (that is, the guide laser beam LB1 may not be used).

The optical disk 11 preferably adopts the CLV method. Concentric or spiral guide tracks TR (specifically, groove tracks GT and land tracks LT described later) include control information (for example, tracking error signals, clock information, and address information) in accordance with the CLV method. , Recording start timing information, etc., or wobble information or pit information as a basis for these information). In the present embodiment, such control information uses a mark group MG in which the same recording marks MR formed at the same rotational phase position of a plurality of guide tracks TR adjacent along the radial direction of the optical disk 11 are combined. Are recorded. Such a mark group MG is preferably formed in advance on the guide layer 12 (in other words, the guide track TR included in the guide layer 12) when the optical disc 11 is manufactured.

The guide track TR formed on the guide layer 12 may be a single spiral. In this case, the groove track GT is preferably switched to the land track LT in a predetermined region of the guide layer 12. Similarly, the land track LT is preferably switched to the groove track GT in a predetermined region of the guide layer 12. However, the guide track TR may be a double spiral in which the groove track GT and the land track LT are separated.

As shown in FIG. 2, the recording / reproducing laser beam LB2 is focused on one desired recording layer 13 to be recorded or reproduced among the plurality of recording layers 13 stacked on the guide layer 12. The recording / reproducing laser beam LB2 is a blue laser beam having a relatively short wavelength as in, for example, BD (Blu-ray Disc: Blu-ray Disc). On the other hand, the guide laser beam LB1 is a red laser beam having a relatively long wavelength as in the case of DVD, for example. The diameter of the beam spot formed on the guide layer 12 by the guide laser beam LB1 is, for example, about several times the diameter of the beam spot formed on the recording layer 13 by the recording / reproducing laser beam LB2.

Each of the plurality of recording layers 13 is a recording layer capable of optically recording and reproducing recording information independently. More specifically, each of the plurality of recording layers 13 is composed of, for example, a translucent thin film containing a two-photon absorption material. For example, as a two-photon absorption material, a fluorescent type using a fluorescent material in which the fluorescence intensity in a region where two-photon absorption occurs is changed, a refractive index changing type using a photorefractive material in which the refractive index is changed by electron localization, etc. However, it can be adopted. The use of photochromic compounds, bis (aralkylidene) cycloalkanone compounds, etc. is promising as refractive index changing type two-photon absorption materials.

As an optical disk structure using a two-photon absorption material, (i) a bulk type in which the entire optical disk 11 is made of a two-photon absorption material, and (ii) a recording layer of a two-photon absorption material and a spacer layer of another transparent material are alternated. There is a layer structure type laminated on the substrate. The layer structure type has an advantage that focus control can be performed using light reflected at the interface between the recording layer 13 and the spacer layer. The bulk type has an advantage that the manufacturing cost can be suppressed because there are few multilayer film forming steps.

Each of the plurality of recording layers 13 may be, for example, a dye material in addition to the above-described two-photon absorption material and phase change material. In each of the plurality of recording layers 13, the guide track TR is not formed in advance in an unrecorded state, and for example, the entire region is a mirror surface or a flat surface without unevenness.

In the following description, for convenience of explanation, an example in which the groove track GT and the land track LT have a straight structure is shown. However, the wobbling may be appropriately performed on the groove track GT and the land track LT. For example, in each of the groove track GT and the land track LT, a reflective film made of, for example, a light-reflective material is formed on a transparent film as a substrate on which concave and convex grooves are formed, and is further transparent or opaque as a protective film. It may be formed by being filled with an appropriate film. Wobbling may be performed on the side walls of the groove track GT and the land track LT.

When at least a recording process is performed on the optical disc 11 in which the plurality of recording layers 13 are laminated on the guide layer 12, the guide laser beam LB1 and the optical laser 11 via the common objective lens 102L are provided. The recording / reproducing laser beam LB2 is irradiated almost or coaxially in practice.

In FIG. 1 and FIG. 2, since the tracking control of the recording / reproducing laser beam LB2 does not exist on the recording layer 13 at least before the recording process is performed, the guide layer 12 is guided by the guide laser beam LB1. This is indirectly performed by tracking control for the guide track TR. That is, the guide laser beam LB1 and the recording / reproducing laser beam LB2 are irradiated through a common optical system such as the objective lens 102L. For this reason, the positioning of the guide laser beam LB1 in the plane of the optical disc 11 (that is, in the recording surface of the guide layer 12) is directly within the plane of the optical disc 12 of the recording / reproducing laser beam LB2 (that is, the recording surface of each recording layer 13). It can be used for positioning in the inner).

In the guide track TR of the guide layer 12, a plurality of mark groups MG each having a physical structure carrying control information such as a tracking error signal (or a signal such as a wobble signal as a source thereof) and address information are arranged. .

(1-2) Physical Structure of Guide Layer 12 Next, the physical structure of the guide layer 12 will be described in detail with reference to FIGS. FIG. 3 to FIG. 6 are perspective views of a part of the guide track TR on which the wobbling in the guide layer 12 is performed. In particular, FIG. 3 is a perspective view showing a part of the guide track TR simply wobbled. FIG. 4 is a perspective view showing a part of the guide track TR in which the groove track GT, the land track LT and the like are formed without gaps over the entire area of each guide track TR. FIG. 5 is a perspective view showing a part of the guide track TR having the “wobble and partially cutout structure” and wobbling. FIG. 6 is a perspective view showing a part of a guide track TR having “wobble and narrow land pre-pit” and wobbling.

As shown in FIG. 3, the guide layer 12 has a groove track GT corresponding to a specific example of the guide track TR shown in FIG. In the groove track GT, for example, a reflective film 12a, which is a thin film made of a light-reflective material, is formed on a transparent film 12c as a substrate on which concave and convex grooves are formed, and further a transparent or opaque film as a protective film 12b is formed by filling the concave and convex grooves of the reflective film 12a. In the meaning of a groove dug in the transparent film 12c as a base material located on the upper side in FIG. 3, the groove track GT is formed in a convex shape on the upper side in FIG. Or conversely, in the groove track GT, the reflective film 12a is formed on the transparent or opaque film 12b as the base material on which the concave and convex grooves are formed, and the transparent film 12c as the protective film is further provided with the concave and convex portions of the reflective film 12a. It may be formed by filling the groove.

The groove track GT has a wobble WB on the side wall. In other words, the groove track GT is formed such that the side wall wobbles (meanders) along the track direction.

In FIG. 3, the groove as a physical groove is locally formed in a part of the groove track GT. On the other hand, a virtual groove track GT indicated by a one-dot chain line is an information track that the recording layer 13 has after recording data on the recording layer 13 (that is, an array of recording marks constituting recorded data). Are arranged at a track pitch corresponding to the track pitch. Here, the arrangement on the recording layer 13 of the data along the guide track TR that has already been recorded along the guide track TR of the guide layer 12 will be referred to as an “information track” as appropriate. The information track is physically a characteristic altered portion (for example, a portion where the fluorescence intensity has changed, a portion where the refractive index has changed, a phase change, etc. formed on the recording surface of the recording layer 13 by the irradiation of the recording / reproducing laser beam LB2. It can be said that a series of formations along the guide track TR of the guide layer 12 of the change portion, the dye change portion, and the like. For this reason, even in the groove track GT in which no groove as a physical groove in FIG. 3 is formed, the groove is formed at a frequency at which control information such as a tracking error signal and address information can be generated at a predetermined frequency. ing. That is, at the radial position and the track direction position not shown in FIG. 3, grooves are appropriately formed on the groove track GT, and the groove track GT on which no groove is formed over the circumference is Basically does not exist.

Note that, as shown in FIG. 4, the groove and the entire area in the track direction and the radial direction have a track pitch corresponding to the track pitch of the information track that the recording layer 13 has after recording data on the recording layer 13. A land may be formed. That is, also in the present embodiment, the information track of the recording layer 13 and the guide track TR of the guide layer 12 may have a one-to-one correspondence as in the case of traditional DVD and BD. That is, also in this embodiment, the guide track TR may have a land / groove structure.

In the example shown in FIG. 4, as will be described in detail later, the mark group MG arranged on the groove track GT and the land track LT is not formed over the entire area along the track direction. The mark group MG is formed so as not to be adjacent to each other in the radial direction. A quantitative description of the arrangement of the mark groups MG (more specifically, the arrangement interval of the mark groups MG in the track direction and the radial direction) and the operation and effect thereof will be described later with reference to FIGS. Detailed description.

On the other hand, in the example of FIG. 3, the groove is not formed over the entire area along the track direction on the groove track GT. The grooves are not formed on the groove tracks GT adjacent to each other in the radial direction. Note that the groove arrangement (more specifically, the groove arrangement interval in the track direction and the radial direction) is the mark group MG arrangement (more specifically, the mark group MG in the track direction and the radial direction). (Arrangement interval) may be substantially the same. That is, the arrangement mode of the mark group MG described in detail later may be substantially the same as the arrangement mode of the grooves formed only in a part of the region along the track direction. As shown in FIG. 2, the groove track GT formed in the guide layer 12 may be formed with a groove notch GN1 having a partially cut structure. The notch is a mirror surface that is cut out over the track width of one groove track GT. The groove notch GN1 is an example of the recording mark 22 (see FIG. 9) constituting the mark group MG.

Alternatively, as shown in FIG. 6, land prepits LPP <b> 1 may be formed on the land track LT formed on the guide layer 12. Also in FIG. 4, land pre-pits LPP1 are formed. The groove notch GN1 in FIG. 5 and the LPP1 in FIG. 6 are detected as signals having the opposite polarity when the guide layer 12 is reproduced, but have the same effect that desired information can be retained. The land prepit LPP1 is an example of the recording mark 22 (see FIG. 9) constituting the mark group MG.

Here, with reference to FIG. 7 and FIG. 8, considerations will be added when constructing a physical structure carrying control information such as tracking error signals and address information in the guide track TR of the guide layer 12.

As shown in FIG. 7, when the beam spot SP1 formed by the guide laser beam LB1 on the guide layer 12 is not relatively large with respect to the track pitch of the guide track TR (that is, tracking for relatively low density recording). Assuming control). For example, it is assumed that the track pitch of the guide track TR is 0.5 μm while the diameter of the beam spot SP1 is about 0.5 μm. In this case, the control information acquired from the return light from the guide track TR2 that the guide laser beam LB1 follows is irradiated with the guide laser beam LB1 on other guide tracks TR1 and TR3 different from the guide track TR2. The signal is not affected by the noise as a noise, or practically not at all. That is, with respect to all the tracks TR1, TR2, TR3,..., There are no gaps in the radial direction and the track direction, a groove structure or a wobble structure (see FIG. 3), a partially cut-out structure (see FIG. 5), Even if the pre-pit structure (see FIG. 6) is formed, crosstalk does not occur in the tracking error signal (or the wobble signal that is the source). For this reason, tracking control is suitably performed.

On the other hand, as shown in FIG. 8, it is assumed that the beam spot SP1 is relatively larger than the track pitch of the guide track TR (that is, when tracking control for high-density recording is performed). For example, it is assumed that the track pitch of the guide track TR is 0.25 μm while the diameter of the beam spot SP1 is about 0.5 μm. In this case, the control information acquired from the return light from the guide track TR3 followed by the guide laser beam LB1 is applied to the other guide tracks TR2 and TR4 different from the guide track TR3. The signal is significantly affected as a noise. That is, if all the guide tracks TR1, TR2, TR3,... Have a physical structure (see FIGS. 3 to 6) without gaps in the radial direction and the track direction, crosstalk occurs in the tracking error signal. It occurs remarkably. For this reason, it is difficult or impossible to suitably perform tracking control.

In particular, in the case of the CLV method as in this embodiment, unlike the case of the CAV method, the address positional relationship (for example, an address difference) on a plurality of adjacent guide tracks TR changes depending on the radial position. . For this reason, even if tracking control can be performed in one place, tracking control is performed in another place (that is, in a place where the degree of proximity of another signal generation region adjacent in the radial direction becomes strong). There is a significant possibility that it will be difficult or impossible to perform the operation.

Such a technical problem such as crosstalk can occur in the same manner when the land pre-pit LPP1 exists in the vicinity of the guide track TR3 followed by the guide laser beam LB1, as shown in FIG. That is, a signal acquired from the land prepit LPP1 formed on the other guide track TR4 is different from a signal acquired from the land prepit LPP1 formed on the guide track TR3 that the guide laser beam LB1 follows. It affects as noise. As a result, it may be difficult to stably detect the land prepit LPP1. In other words, it may be difficult to detect address information or the like by the land pre-pit LPP1.

In the situation shown in FIG. 8, the recording layer 13 is irradiated with the recording / reproducing laser beam LB2 corresponding to the high density recording, while the guide layer 12 is irradiated with the guide laser beam LB1 corresponding to the low density recording. In addition, when the guide tracks TR having a narrow pitch are formed in advance on the guide layer 12 so that the information tracks formed on the recording layer 13 after data recording have a narrow pitch, they are inevitably generated. If a guide track TR having a wide pitch corresponding to the guide laser beam LB1 is formed on the guide layer 12, the guide track TR serves to perform tracking control for high density recording in the recording layer 13. Because it doesn't stand at all.

Here, in order to perform tracking control in a predetermined frequency band, it is necessary to detect control information such as a tracking error signal and address information at any timing in any guide track TR. However, the control information can be detected without forming a wobble structure or pre-pit structure (see FIGS. 3 to 6) for detecting the control information continuously in the track direction on the guide track TR. That is, if the mark group MG constituting the control information is arranged at an arrangement interval (that is, arrangement pitch) that is equal to or less than the longest distance at which tracking control can be performed in a predetermined frequency band, It is not necessary to form a wobble structure or pre-pit structure (that is, mark group MG) for detecting control information in the entire area along the track direction. Moreover, if attention is paid to a plurality of guide tracks TR adjacent to each other along the radial direction, the positions are aligned in the radial direction (that is, the same rotational phase position, in other words, the same angle or the same angle on the optical disk 11). The wobble structure or pre-pit structure (that is, the mark group MG) for detecting the control information does not have to be aligned.

Therefore, in this embodiment, in particular, in order to achieve the specific purpose that the tracking control is mainly possible for the guide track TR, the plurality of mark groups MG are both in the track direction and the radial direction as described below. , Provided discretely.

(1-3) Arrangement Mode of Mark Group MG Next , the arrangement mode of the mark group MG in the guide track TR will be described in detail with reference to FIG. 9 and FIG.

As shown in FIG. 9, a plurality of mark groups MG are arranged on the guide track TR in the guide layer 12. Each of the plurality of mark groups MG includes the same plurality of recording marks 22 arranged at the same rotational phase position. FIG. 9 shows that each of a plurality of mark groups has the same three recording marks 22 arranged at the same rotational phase position (that is, the same three phase marks arranged at the same rotational phase position of three adjacent guide tracks). An example including a recording mark 22) is shown. Note that the plurality of recording marks 22 included in one mark group MG may not be the same as the plurality of recording marks 22 included in another mark group MG. Each of the plurality of recording marks 22 has a physical structure such as a wobble structure or a prepit structure, as shown in FIGS. For example, in the example shown in FIG. 10, each of the plurality of recording marks 22 is a partial wobble WBL on a guide track TR (see FIG. 4) in which grooves and lands are formed over the entire area in the track direction and the radial direction. It is an example when it is comprised from. In FIG. 10, each recording mark 22 is a pair of recording marks 22 (that is, partial wobbles WBL) shifted equidistantly from the center of the groove track GT in the left-right direction. However, on the guide track TR (see FIG. 4) in which grooves and lands are formed over the entire area in the track direction and the radial direction, each of the plurality of recording marks 22 is a component other than the partial wobble WBL (for example, Land pre-pits LPP1 etc.). Control information such as tracking error signals and address information is acquired from the plurality of mark groups MG (in other words, the plurality of recording marks 22).

The plurality of mark groups MG are discretely arranged along the track direction (left-right direction in FIG. 9). Specifically, in this embodiment, the “discrete arrangement of the plurality of mark groups MG in the track direction” is positioned at the center in the radial direction among the plurality of recording marks 22 included in each of the plurality of mark groups MG. This is realized by paying attention to the center mark (the recording mark 22 in FIG. 9 where the arrow indicating the traveling direction of the guide laser beam LB1 is located).

More specifically, in order to achieve a discrete arrangement of the plurality of mark groups MG in the track direction, eight slots (for example, slot # 1 to slot # 1 in FIG. A maximum of one center mark 22 is arranged for each group composed of # 8). That is, a plurality of different center marks 22 included in different mark groups MG are not simultaneously arranged in each group. However, there may be a group in which one central mark 22 is not arranged. The arrangement interval of the center marks 22 when arranging the center marks 22 for each group is such that tracking error signals, address information, and the like are made at a frequency that enables stable tracking control in a predetermined frequency band. The distance is preferably shorter than the longest distance at which control information can be generated by a slight margin.

More specifically, for example, when focusing on the guide track T-4, a center mark is arranged on the guide track T-4 at a position corresponding to the slot # 1, and the center mark is placed in the same group as the slot # 1. No other center mark is arranged at a position corresponding to slot # 2 to slot # 8 to which it belongs. Similarly, when attention is paid to the other guide tracks T-8 to T + 16, only one of the eight slots constituting one group is included in one mark group MG. The center mark 22 is arranged, and other center marks 22 included in the other mark group MG are not arranged in other slots.

FIG. 9 shows an example in which one group is composed of eight slots. However, one group may be composed of 7 or less slots or 9 or more slots arranged continuously in the track direction.

In addition, the plurality of mark groups MG are arranged so as not to be adjacent to each other along the radial direction (vertical direction in FIG. 9).

In order to realize such an arrangement that the plurality of mark groups MG are not adjacent to each other along the radial direction, at least two mark groups MG among the plurality of recording mark groups MG are displaced along the radial direction. May be arranged. That is, at least two mark groups MG among the plurality of recording mark groups MG may be arranged so as to have a gap (for example, a gap of a predetermined number of tracks) in the radial direction. In addition, it is preferable that this clearance gap is an area | region of a mirror surface state or a straight groove structure or a straight land structure, for example. In this case, the two mark groups MG shifted along the radial direction may be arranged at the same rotational phase position. Alternatively, the two mark groups MG that are displaced along the radial direction may be arranged at different rotational phase positions. For example, in FIG. 9, the mark group MG disposed in the slot # 2 from the guide track T-6 to the guide track T is the same as the mark group MG disposed in the slot # 3 from the guide track T + 12 to the guide track T + 16. Although arranged at the rotational phase position, they are arranged at positions shifted from each other along the radial direction. Therefore, it can be said that these two mark groups MG are not adjacent to each other along the radial direction.

Alternatively, in order to realize an arrangement in which the plurality of mark groups MG are not adjacent to each other along the radial direction, at least two marks MG of the plurality of recording mark groups MG are arranged so as to be displaced along the track direction. May be. That is, at least two mark groups MG among the plurality of recording mark groups MG may be arranged so that the rotational phase positions to be arranged are different from each other by shifting along the track direction. For example, in FIG. 9, the mark group MG arranged in the slot # 2 from the guide track T-6 to the guide track T and the mark group MG arranged in the slot # 2 from the guide track T + 2 to the guide track T + 8 are It arrange | positions in the position which mutually shifted | deviated along the direction. Therefore, it can be said that these two mark groups MG are not adjacent to each other along the radial direction.

Due to the discrete arrangement of the plurality of mark groups MG along the track direction and the non-adjacent arrangement of the plurality of mark groups MG along the radial direction, the guide laser light LB1 is included in different mark groups MG. A positional relationship is realized such that the central mark 22 is not irradiated simultaneously. In other words, the guide laser beam LB1 is distributed in the discrete arrangement positions and radial directions of the plurality of mark groups MG along the track direction so that the different center marks 22 included in the different mark groups MG are not simultaneously irradiated. It is preferable that each of the arrangement positions of the plurality of mark groups MG along which they are not adjacent to each other is appropriately determined.

In addition, in this embodiment, each recording mark 22 includes a front buffer area 21a positioned in front of the recording mark 22 along the track direction, and a rear buffer positioned behind the recording mark 22 along the track direction. It arrange | positions so that it may be pinched | interposed between the area | regions 21b.

In the present embodiment, it is preferable that the front buffer area 21a, the recording mark 22 and the rear buffer area 21b correspond to one slot. By arranging the mark group MG to which the front buffer area 21a and the rear buffer area 21b are attached in slot units, it becomes easy to find the mark group MG along the guide track TR. As a result, the tracking error signal and the address information can be detected stably and reliably, so that stable tracking control can be performed.

Each of the front buffer region 21a and the rear buffer region 21b is a region having a mirror surface structure, or a region having a straight groove structure or a straight land structure. A buffer period in each of the front buffer area 21a and the rear buffer area 21b provides a preparation period for reading the recording mark 22. In particular, when the recording mark 22 has a physical structure having a wobble structure, if the front buffer area 21a located in front of the recording mark 22 is a straight groove structure, the guide laser beam is forwarded while performing tracking control. The recording mark 22 is plunged from the buffer area 21a.

Further, in this embodiment, since the optical disk 11 employs the CLV system, as shown in FIG. 9, the slots adjacent to each other along the radial direction are slightly shifted along the track direction. For this reason, if the relative arrangement position of each of the plurality of recording marks 22 included in the same mark group MG is fixed, all of the plurality of recording marks 22 included in the same mark group MG are stored. It becomes difficult to arrange at the same rotational phase position. Therefore, in this embodiment, the plurality of front buffer areas 21a disposed in front of the plurality of recording marks 22 included in the same mark group MG and the plurality of recording marks 22 included in the same mark group MG. By adjusting the length of each of the plurality of rear buffer areas 21b in the track direction, all of the plurality of recording marks 22 included in the same mark group MG are arranged at the same rotational phase position. That is, in this embodiment, a plurality of front buffer areas arranged in front of the plurality of recording marks 22 so that the start end portions of the plurality of recording marks 22 included in the same mark group MG are aligned along the radial direction. Each length of 21a is set to a different length. Similarly, each of the plurality of rear buffer regions 21b arranged in front of the plurality of recording marks 22 is arranged so that the terminal portions of the plurality of recording marks 22 included in the same mark group MG are aligned in the radial direction. The lengths are set to different lengths.

As described above, the plurality of mark groups MG are arranged so as to be discrete along the track direction and not adjacent to each other along the radial direction as described above. For this reason, even if the track density is increased until the beam spot SP1 of the guide laser beam LB1 extends over the three adjacent guide tracks TR, the tracking error signal and the address obtained by irradiating the mark group MG with the guide laser beam LB1. Crosstalk such as information can be reliably reduced.

Thus, since the guide track TR has the physical structure described with reference to FIGS. 1 to 8, the track pitch can be narrowed while preventing the execution of tracking control and the acquisition of address information and the like. it can.

Particularly in this embodiment, the mark group MG (specifically, the recording mark 22 included in the mark group MG) is created or not created in slot units, so that it is easy to detect a tracking error signal or the like. And can be executed stably.

At this time, the length of the slot on the guide track TR in the track direction and the structural unit in the format of data to be recorded on the recording layer 13 (for example, ECC block, RUB (Recording Unit Block), ADIP unit, etc.) Etc.) in the track direction is preferably a predetermined integer ratio. With this configuration, the frequency of occurrence of tracking error signals and the like, the frequency of acquisition of address information, and the period of recording data on the recording layer 13 at the recording surface position corresponding to the guide track TR are not limited to the radial position. In addition, it is easy to maintain a certain relationship without depending on the track position. In particular, even with the CLV method, stable tracking control can be performed at an arbitrary radial position.

In addition, in this embodiment, each mark group includes the same plurality of recording marks 22 arranged at the same rotational phase position of each of the plurality of guide tracks TR adjacent to each other along the radial direction. For this reason, the dependence of the guide laser beam LB1 on the focus deviation (focus offset) is weakened (specifically, the control information indicated by the mark group MG is preferably read even when the focus deviation increases). Can do.

As described above in detail, according to the present embodiment, the track pitch and recording linear density that can be recorded or reproduced in the recording layer 13 are the original purposes in the multilayer recording type optical disc 11 while adopting the CLV method. It can be increased to such an extent that it can be said to be “high density recording”.

In the above description, an example in which both the tracking error signal and the address information (or other arbitrary control information, the same applies hereinafter) is acquired from the plurality of mark groups MG is described. However, while one of the tracking error signal and the address information is acquired from the plurality of mark groups MG, the other of the tracking error signal and the address information may not be acquired. For example, when a guide track TR in which grooves and lands are formed over the entire area in the track direction and the radial direction is used, the tracking error signal follows components other than the mark group MG (that is, the guide track TR). Can be obtained from the return light of the guide laser beam LB1. Therefore, in this case, the address information is acquired from the plurality of mark groups MG, but the tracking error signal may not be acquired. However, even in this case, the plurality of mark groups MG have such a degree that address information (or arbitrary control information) acquired from the mark group MG can be acquired in a predetermined band (in other words, a predetermined cycle). It is preferable to arrange discretely along the track direction. For example, when a recording clock is generated from a plurality of mark groups MG, the arrangement interval between the center marks 22 included in each mark group MG (for example, the length in the track direction of the group described above) is determined as the recording clock. It is preferable that the distance is set to a predetermined distance or less than that according to the clock generation band.

(2) Recording / Reproducing Device Next, the recording / reproducing device 101 of this embodiment will be described with reference to FIGS.

(2-1) Configuration of Recording / Reproducing Device First, the configuration of the recording / reproducing device 101 of this embodiment will be described with reference to FIG. FIG. 11 is a block diagram showing the configuration of the recording / reproducing apparatus 101 of this embodiment.

As shown in FIG. 11, the recording / reproducing apparatus 101 is configured as a disk drive, and is connected to the host computer 201.

The recording / reproducing apparatus 101 includes an optical pickup 102, a signal recording / reproducing unit 103, a spindle motor 104, a bus 106, a CPU (drive control unit) 111, a memory 112, and a data input / output control unit 113. During recording, the guide laser beam LB1 and the recording / reproducing laser beam LB2 are irradiated through the objective lens 102L (see FIG. 2) of the optical pickup 102. During reproduction, only the recording / reproducing laser beam LB2 also serving as a tracking control light beam or both the guide laser beam LB1 and the recording / reproducing laser beam LB2 are irradiated through the objective lens 102L.

The host computer 201 includes an operation / display control unit 202, operation buttons 202, a display panel 204, a bus 206, a CPU 211, a memory 212, and a data input / output control unit 213. At the time of recording, data to be recorded is input from the data input / output control unit 213. During reproduction, the reproduced data is output from the data input / output control unit 213.

The optical pickup 102 includes a red semiconductor laser that emits a guide laser beam LB1, a blue semiconductor laser that emits a recording / reproducing laser beam LB2, and a combining / separating optical system including an objective lens 102L, a prism, a mirror, and the like. The optical pickup 102 irradiates the guide laser beam LB1 and the recording / reproducing laser beam LB2 coaxially and with different focus (see FIGS. 1 and 2) through a common objective lens 102L.

Further, the optical pickup 102 receives the return light from the optical disk 11 caused by the guide laser beam LB1 through the objective lens 102L, and a light receiving element such as a two-divided or four-divided CCD, and the recording / reproducing laser beam LB2. It includes a light receiving element such as a two-divided or four-divided CCD that receives the return light from the optical disk 11 via the objective lens 102L. The optical pickup 102 modulates the recording / reproducing laser beam LB2 with a relatively high recording intensity during recording. Further, the optical pickup 102 sets the light intensity of the recording / reproducing laser beam LB2 to a relatively low reproducing intensity during reproduction.

The optical pickup 102 and the signal recording / reproducing unit 103 perform tracking using, for example, a push-pull method or a phase difference method (DPD) based on a light receiving signal from a light receiving element that receives return light from the guide layer 12 at least during recording. Generate an error signal. The optical pickup 102 and the signal recording / reproducing unit 103 further reproduces the address information based on the light reception signal from the light receiving element that receives the return light from the guide layer 12 at least during recording.

The optical pickup 102 and the signal recording / reproducing unit 103 generate a tracking error signal by the push-pull method or the phase difference method, for example, based on the light receiving signal from the light receiving element that receives the return light from the recording layer 13 during reproduction. Alternatively, the optical pickup 102 and the signal recording / reproducing unit 103 may generate a tracking error signal based on the light reception signal from the light receiving element that receives the return light from the guide layer 12 during reproduction. The optical pickup 102 and the signal recording / reproducing unit 103 further generate a data signal, for example, as a signal corresponding to the total amount of light based on the light reception signal from the light receiving element that receives the return light from the recording layer 13 at least during reproduction. .

The memory 112 and the memory 212 are (i) a computer for controlling each element such as the CPU 111 in the recording / reproducing apparatus 101 and each element such as the CPU 211 in the host computer 201 so that the recording / reproducing process described below is performed. Program, and (ii) various data such as control data, in-process data, processed data, etc. necessary for recording / reproduction processing are appropriately used to temporarily or permanently hold the data via the bus 106, bus 206, etc. It is done.

(2-2) Operation of Recording / Reproducing Device Next, the operation of the recording / reproducing device 101 of this embodiment will be described with reference to FIGS. FIG. 12 is a flowchart showing an overall flow of operations performed by the recording / reproducing apparatus 101. FIG. 13 is a flowchart showing a detailed flow of an example of the recording process. FIG. 14 is a flowchart showing a detailed flow of an example of the reproduction process. FIG. 15 is a flowchart showing another example flow of the reproduction process.

In FIG. 12, first, the above-described optical disc 11 of the present embodiment is mounted on the recording / reproducing apparatus 101 by manual or mechanical operation by the user (step S11).

Then, an operation start command corresponding to an operation on the operation button 203 when the user looks at the display panel 204 is generated by the drive-side operation / display control unit 202 and the CPU 111, the host-side CPU 211, and the like. In response to this operation start command, rotation of the optical disk 11 by the spindle motor 104 is started under the control of the signal recording / reproducing unit 103. Before and after this, light irradiation by the optical pickup 102 is started under the control of the signal recording / reproducing unit 103. Further, the reading servo system for the guide layer 12 is operated. That is, the guide laser beam LB1 is irradiated and condensed on the guide layer 12, and tracking control is started (step S12).

The various commands including the operation start command and various data including user data and control data are transferred by the host side bus 206 and the data input / output control unit 213, and the drive side bus 106 and the data input / output control unit. 113.

Subsequently, irradiation of the guide track TR with the guide laser beam LB1 is continued on the guide layer 12, and a wobble signal and a prepit signal (further, a tracking error signal obtained from at least one of them by the push-pull method or the DPD method). Is detected from the mark group MG. Further, disk management information recorded in advance as at least one of these signals is acquired by the CPU 111 on the drive side or the CPU 211 on the host side.

Note that the disc management information may be recorded together in a lead-in area, a TOC (Table Of Content) area, or the like located on the innermost circumference side in the guide layer 12. The contents of the disc management information may be compliant with the disc management information in an existing DVD or BD. However, the disc management information is separately recorded in advance or separately in a lead-in area or TOC area specially provided in the recording layer, and the disc management information is recorded at this time or at an arbitrary time. It may be read out.

Next, it is determined whether or not the requested operation is data recording by the CPU 111 on the drive side or the CPU 211 on the host side (step S14). Here, when it is determined that the requested operation is data recording (step S14: Yes), a recording process for the new optical disc 11 is executed (step S15). This recording process will be described later in detail (see FIG. 13).

On the other hand, if it is determined in step S14 that the requested operation is not data recording (step S14: No), or if the recording process for the new optical disc 11 is completed in step S15, the drive side The CPU 111 or the host-side CPU 211 determines whether or not the requested operation is data reproduction (step S16). If it is determined that the requested operation is data reproduction (step S16: Yes), reproduction processing for a new optical disc 11 is executed (step S17). This reproduction process will be described later in detail (see FIGS. 14 and 15).

If it is determined in step S16 that the requested operation is not data reproduction (step S16: No), or if the reproduction process for the new optical disk 11 is completed in step S17, ejection (that is, an optical disk is mounted). It is determined whether or not the ejection of the disc tray is requested via the operation button 203 or the like (step S18). Here, when it is determined that the ejection is not requested (step S18: No), the operations after step S14 are repeated again.

On the other hand, if it is determined in step S18 that ejection is required (step S18: Yes), the ejection operation is executed (step S19), and a series of recording / reproducing processes on the optical disc 11 is completed.

Next, an example of a recording process (step S15 in FIG. 12) for the new optical disc 11 will be described with reference to FIG.

In FIG. 13, when the recording process is started, first, irradiation of the guide track TR with the guide laser beam LB1 is continued on the guide layer 12 under the control of the CPU 111 and the signal recording / reproducing unit 103 (that is, While the tracking control is being performed), the wobble signal and the pre-pit signal are detected from the mark group MG. As a result, the address information on the guide track TR is acquired by the CPU 111 or the like. By referring to this address information, the CPU 211 or the like searches for a desired recording address designated as an address at which data recording should be started. That is, the guide laser beam LB1 is moved to a position corresponding to the desired recording address. By this search operation, the recording / reproducing laser beam LB2 that shares the optical system such as the objective lens 102L in the optical pickup 102 with the guide laser beam LB1 also corresponds to the desired recording address searched on the recording layer 13. The position is moved (step S21).

Subsequently, under the control of the CPU 111 and the signal recording / reproducing unit 103, the optical pickup 102 performs focus control of the recording / reproducing laser beam LB2 for the desired recording layer 13 on which data is to be recorded (step S22).

Subsequently, in a state in which focus control is performed by the optical pickup 102, the recording / reproducing laser beam LB2 is irradiated while being modulated according to the data value to be recorded, thereby recording data on a desired recording layer 13. Is started (step S23).

Subsequently, it is monitored by the CPU 111 or the like whether or not a predetermined amount of recording has been completed (step S24). Here, as long as the recording is not completed, the data recording to the recording layer 13 is continued (step S24: No).

Here, when the recording is completed (step S24: Yes), the disc management information is updated according to the recorded data (step S25). The disc management information may be recorded together in a lead-in area, a TOC area, or the like provided in at least one of the plurality of recording layers 13. The position may be on the inner peripheral side, but may be on the outer peripheral side or in the middle, or may be recorded in a somewhat dispersed form. In addition to or instead of this, the disk management information provided in the memory 112, the memory 212, and the like and associated with the optical disk 11 may be updated.

Thus, a series of recording processes for the new optical disk 11 (step S15 in FIG. 12) is completed.

Next, with reference to FIG. 14, an example of a reproduction process (step S17 in FIG. 12) for the new optical disk 11 will be described. In this example, the guide laser beam LB is not used for tracking control during the reproduction process. That is, in this example, unlike the recording process, the recording / reproducing laser beam LB2 is used for tracking control.

In FIG. 14, under the control of the CPU 111 and the signal recording / reproducing unit 103, the optical pickup 102 performs focus control of the recording / reproducing laser beam LB2 for the desired recording layer 13 from which data is to be reproduced. Before or after this, tracking control for the information track by the recording / reproducing laser beam LB2 is performed (step S31).

Subsequently, recorded address information on the information track is acquired by the CPU 111 or the like. By referring to this address information, a desired reproduction address designated as an address at which reproduction of desired data is to be started is searched by the CPU 211 or the like. That is, the recording / reproducing laser beam LB2 is moved to a position corresponding to a desired reproduction address (step S32).

Subsequently, in a state where tracking control and focus control are performed by the optical pickup 102, reflected light caused by the recording / reproducing laser beam LB2 is received through the objective lens 102L, so that the desired pickup from the recording layer 13 is obtained. Data reproduction is started (step S33).

Subsequently, it is monitored by the CPU 111 or the like whether or not the predetermined amount of reproduction has been completed (step S34). Here, the reproduction of data from the recording layer 13 is continued unless the reproduction ends (step 34: No).

Here, when the reproduction is finished (step S34: Yes), a series of recording processes for the new optical disc 11 (step S17 in FIG. 12) is completed.

Next, with reference to FIG. 15, another example of the reproduction process for the new optical disk 11 (step S17 in FIG. 12) will be described. In this example, the guide laser beam LB is used for tracking control or the like not only during the recording process but also during the reproduction process.

In FIG. 15, under the control of the CPU 111 and the signal recording / reproducing unit 103, the optical pickup 102 performs focus control of the guide laser beam LB1 with the guide layer 12 as a target. Before or after this, tracking control of the guide laser beam LB1 is performed for the guide track TR. Further, the address information is acquired from the wobble or pre-pit on the guide track TR by the CPU 111 or the like. By referring to this address information, the CPU 211 or the like searches for a desired reproduction address designated as an address at which data reproduction should be started. That is, the guide laser beam LB1 is moved to a position corresponding to a desired reproduction address. By this search operation, the recording / reproducing laser beam LB2 sharing the optical system such as the objective lens 102L with the guide laser beam LB1 in the optical pickup 102 is also moved to a position corresponding to the searched reproduction address on the recording layer 13. It is moved (step S41).

Subsequently, under the control of the tracking control, the focus control of the recording / reproducing laser beam LB2 is performed on the desired recording layer 13 from which data is to be reproduced by the optical pickup 102 under the control of the CPU 111 and the signal recording / reproducing unit 103. Performed (step S43).

Subsequently, in a state where the tracking control of the guide laser beam LB1 is performed by the optical pickup 102 and the focus control of the recording / reproducing laser beam LB2 is performed, the reflected light caused by the recording / reproducing laser beam LB2 is reflected on the objective lens. Light is received through 102L. As a result, data reproduction from the desired recording layer 13 is started (step S43).

Subsequently, it is monitored by the CPU 111 and the like whether or not the predetermined amount of reproduction has been completed (step S44). Here, the reproduction of data from the recording layer 13 is continued unless the reproduction ends (step 34: No).

Here, when the reproduction is finished (step S44: Yes), a series of reproduction processes for the new optical disc 11 (step S17 in FIG. 12) is completed.

(2-3) Arrangement interval in the track direction of the mark group MG Next, referring to FIGS. 16 to 19, the mark group MG is discretely arranged along the track direction for tracking control in a predetermined frequency band. A method of determining the arrangement interval of the mark group MG (in particular, the center mark included in the mark group MG and corresponding to the above-described group length) will be described together with a tracking servo system that performs tracking control.

As shown in FIG. 16, the tracking servo system includes an error detector 301 including a subtractor, a sampler 302 including a sampling switch, a capacitor, and a buffer, an amplifier and an equalizer 303. And an actuator 304.

The error detector 301 receives a disturbance for tracking control (so-called tracking error signal) and a feedback signal from the actuator 304. The error detector 301 outputs a subtraction signal obtained by subtracting (minus addition) the feedback signal from the disturbance for tracking control to the sampler 302.

The sampler 302 is a so-called “zero-order hold circuit” that holds sample values. Specifically, a sampling switch that closes at a desired sampling timing, a capacitor that holds a sample value, and a buffer are provided. The subtraction signal is sampled by the sampling switch at a sampling timing corresponding to the frequency band for which tracking control is performed. The sample value (that is, the subtraction signal sampled by the sampling switch) is held by the capacitor and buffered by the buffer. The sampling timing is generated based on, for example, a wobble signal and a prepit signal detected by a light receiving element that receives the guide laser beam LB1. However, the method of generating the sampling timing is not limited to this, and may be generated according to the medium configuration such as a modified example described later. Further, the configuration of the sampler 302 is not limited to this, and needless to say, a “primary hold circuit” or the like may be used.

The output from the sampler 302 (that is, the output from the buffer) is amplified and equalized by the amplifier / equalizer 303 and further input to the actuator 304.

In response to the input amplification signal, the actuator 304 irradiates the guide laser beam LB1 on the guide layer 12 provided in the optical pickup 102 (accordingly, the irradiation of the recording / reproducing laser beam LB2 on the recording layer 13). Position) is moved in the radial direction. A feedback signal corresponding to the fluctuation is fed back from the actuator 304 to the error detector 301.

Here, in particular, the sampling timing in the sampler 302 will be examined with reference to FIGS.

FIG. 17 schematically shows the operation output of the sampler 302 when the eccentric component that is the maximum element of the disturbance input to the error detector 301 changes. From FIG. 17, it can be seen that the tracking error signal undulates from the plus side to the minus side with a substantially constant period with respect to time.

FIG. 18 shows a Bode plot (Bode Plot of zero-order hold) of the transfer function when “zero-order hold” is performed by the sampler 302. In other words, here, the frequency characteristic of the zero hold is shown, and in particular, the gain characteristic (upper characteristic curve) and phase (lower characteristic curve) are shown superimposed in the Bode diagram. Has been. In this example, a case where sampling is performed at 1 ms is shown, but actually, the sampling is performed at a shorter time interval.

FIG. 18 shows that when the phase characteristic is sampled at 1 KHz, the signal at 100 Hz rotates about several degrees as shown by the characteristic curve portion 1001 in the phase. On the other hand, if the bandwidth around the phase is negligible, 100 Hz, a sample interval of about 10 times (1 KHz) or more is necessary (that is, sampling at a frequency higher than 1 KHz is necessary).

FIG. 19 shows an example of the disturbance characteristic of the optical disc 11 and the open loop characteristic in tracking control. In this example, the “disturbance characteristics of the optical disc 11” has an eccentric component of 35 μm on one side in the region where the frequency is less than 23.1 Hz, and 1.1 m / in the acceleration region where the frequency is 23.1 Hz or more. it is S ^2. That is, the disturbance of the optical disk 11 is generally flat at 64 db corresponding to 35 μm in the region where the frequency is less than 23.1 Hz, and to 0 dB corresponding to 0.022 μm on the higher frequency side than the region. It is going down at the slope of 1.1m / ^{S 2.} The open loop characteristic of the tracking servo is shown as an example of a characteristic capable of suppressing such a disk disturbance. That is, in the characteristic diagram, the open loop characteristic is set to be on the higher gain side at any frequency, and thus disturbance can be suppressed in any frequency band. In this example, f0 (cut-off band) = 2.4 KHz.

In the case of this example described with reference to FIGS. 17 to 19, the “predetermined distance” is determined as follows.

That is, when the frequency band for performing tracking control is 2.4 KHz, for example, the time interval required to reduce the influence of the sampler 302 realized as the hold circuit described above to a negligible level is about 10 times. The time interval corresponding to 24 kHz is T = 1 / (24 × 10 ³ ) = 46.7 [μsec]. From the relationship between this time interval T and the linear velocity of rotation of the optical disc 11 by the spindle motor 104, two mark groups MG (specifically, center marks included in the mark group MG) arranged in a discrete manner in the track direction. As the arrangement interval 22), an example of the longest required distance, that is, an example of the “predetermined distance” according to the present invention is determined.

For example, if the linear velocity v is 4.917 m / sec, the predetermined distance L is L = v × T≈230 [μm]. That is, when the servo area 22 is inserted at a ratio of 8 slots along the guide track TR, the slot configuration is determined such that the length of the 8 slots is shorter than 230 [μm]. Alternatively, it is determined how many slots one mark group 22 (specifically, the center mark 22 included in the mark group MG) is arranged.

Note that the method for determining the arrangement interval of the mark group 22 is not limited to this example, and the required servo band as shown in FIGS. 18 and 19, the linear velocity of the optical disk 11 in the CLV method, and the like are taken into consideration. And decide.

(3) Modified Examples Hereinafter, various modified examples of the embodiment will be described with reference to FIGS.

FIG. 20 shows a physical track configuration formed as the mark group MG (in other words, the recording mark 22 included in the mark group MG) in the above-described embodiment. FIGS. 21 to 23 show modified examples of the physical track configuration formed as the mark group MG (in other words, the recording mark 22 included in the mark group MG).

In FIG. 20, a guide track TR in which a mark group MG is arranged is composed of a wobble WB and a land prepit LPP1. Here, it is preferable that the period of the wobble WB and the period of the land prepit LPP1 are set to an integer multiple relationship, and the land prepit LLP1 is formed at each vertex of the wobble WB. Therefore, the detection of the prepit signal and the wobble signal can be facilitated. In the modification of FIG. 21, a sharp curve in which the wobble amplitude (shake amount) is locally increased at each vertex of the wobble WB1 of the groove track GT. A portion 501 is provided. That is, the guide track TR in which the mark group MG is arranged is formed from the special wobble WB1 without the pre-pit. Also in this case, detection of the wobble signal can be facilitated.

22, the wobble WB2 is formed by wobbling a continuous arrangement itself along the guide track TR of the plurality of grooves 502 dug into pieces. For example, if the wobble WB2 is formed by pre-embossing, the track TRw having such a structure can be constructed as the guide track TR in which the mark group MG is arranged.

In the modified example of FIG. 23, a plurality of grooves 502 dug into pieces that have a constant radial width and an appropriately modulated length in the track direction are continuously formed along the guide track TR. A linear arrangement (in other words, a mark pattern) is the guide track TR. In this modification, the guide track TR is not wobbled. For example, if the mark pattern is formed by pre-embossing, the track TRw having such a structure can be constructed as the guide track TR in which the mark group MG is arranged.

Next, FIG. 24 shows a modification of the basic layer configuration (see FIGS. 1 and 2) of the optical disc 11 in the above-described embodiment. FIG. 24 is a schematic perspective view of the optical disk of the present modified example having the same concept as in FIG.

24, in the modification of the optical disc 11, two

guide layers

12a and 12b are provided. For example, the first track information indicating the address position from the inner periphery to the outer periphery is carried on the guide track TR-a of the guide layer 12a. Second address information indicating an address position from the outer periphery to the inner periphery is carried on the guide track TR-b of the guide layer 12b. In this case, the plurality of recording layers 13 are also preferably divided into a first recording layer 13 recorded according to the first address information and a second recording layer 13 recorded according to the second address information. In this case, tracking control for the first recording layer 13 is preferably performed using the guide layer 12a, and tracking control for the second recording layer 13 is preferably performed using the guide layer 12b. With this configuration, user data is recorded from the inner periphery to the outer periphery in one or more first recording layers 13, and from the outer periphery to the inner periphery in one or more second recording layers 13. Thus, the operation of recording user data is performed efficiently. Moreover, the reliability and stability of the recording process can be remarkably improved by using two types of address information properly. Therefore, it is possible to realize the optical disc 11 capable of continuous bi-directional recording or bidirectional recording arbitrarily or independently.

For example, if the first recording layer 13 is recorded and reproduced from the inner periphery to the outer periphery, and the second layer 13 is recorded and reproduced from the outer periphery to the inner periphery, the two recording layers 13 The time required for switching the target of the recording process or the reproduction process between them is the time for performing the interlayer jump. For this reason, it is extremely advantageous when performing a recording process or a reproducing process continuously across a plurality of recording layers 13. In other words, the same effect as that obtained in a two-layer type optical disc employing a so-called opposite track path can be obtained.

As described above in detail, according to the present embodiment and the modification, the arrangement interval of the mark groups MG along the guide track TR is set to a predetermined distance or less, and the mark groups MG are spread over the entire surface of the optical disc 11. Are arranged discretely. Therefore, it is possible to acquire control information such as a tracking error signal and address information that are continuous by sampling at any position of the guide layer 12 from the inner periphery to the outer periphery of the optical disc 11.

In particular, the length of the structural unit of the data format in the recording layer 13 and the length of the slot are in an integral multiple relationship, and the mark group MG is arranged corresponding to the slot. For this reason, the mark group MG in the other guide track TR adjacent to the guide track TR that the guide laser beam LB1 follows is not read simultaneously (that is, no crosstalk occurs in the wobble signal or the prepit signal). ), The adaptive arrangement of the mark group MG is facilitated.

Further, the present invention can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and an information recording medium, a recording / reproducing apparatus, and a method with such a change are also included. It is also included in the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 11 Optical disk 12 Guide layer 13 Recording layer 21a Front buffer area 22 Recording mark 21b Back buffer area TR Guide track WB Wobble LLP1 Land prepit LB1 Guide laser beam LB2 Recording / reproducing laser beam 102 Optical pickup 102L Objective lens 101 Recording / reproducing apparatus 201 Host computer

Claims

A CLV recording medium,
A guide layer in which a guide track divided by a plurality of slots arranged in the track direction is formed in advance;
A plurality of recording layers laminated on the guide layer,
The guide track includes a plurality of identical recording marks formed at the same rotational phase position of a plurality of guide tracks adjacent to each other along a radial direction intersecting the track direction and formed in accordance with the unit of the slot. Multiple mark groups are arranged,
Among each of the plurality of recording marks included in each of the plurality of mark groups in each group including a predetermined number of slots arranged continuously along the track direction among the plurality of slots, along the radial direction. The plurality of mark groups are discretely arranged along the track direction so that a maximum of one central mark located at the center is arranged,
The plurality of mark groups are arranged shifted along at least one of a radial direction and a track direction so as not to be adjacent to each other along the radial direction.
Each of the plurality of mark groups is (i) arranged in front of the plurality of recording marks included in each of the mark groups and has a different length along the track direction. A plurality of front buffer areas, and (ii) a plurality of rear buffer areas that are respectively arranged behind the plurality of recording marks included in the respective mark groups and have different lengths along the track direction. It is arranged to be sandwiched between
Each of the plurality of front buffer regions and the plurality of rear buffer regions has a length such that the plurality of recording marks included in a mark group sandwiched therebetween are formed at the same rotational phase position. The recording medium according to claim 1.
The plurality of mark groups include one recording mark, one front buffer area disposed in front of the one recording mark, and one rear buffer area disposed behind the one recording mark. The recording medium according to claim 2, wherein the recording medium is arranged so as to be arranged in one slot.
The length in the track direction of each of the plurality of slots and the length in the track direction of the structural unit of the data format to be recorded in each of the plurality of recording layers have a predetermined integer ratio. The recording medium according to claim 1, wherein the track is divided into the plurality of slots.
2. The recording medium according to claim 1, wherein the plurality of slots have the same length in the track direction and are arranged in the track direction.
The recording medium according to claim 1, wherein each of the plurality of recording marks includes a wobble or a pre-pit structure.
The guide track is a guide track for tracking servo,
Each of the plurality of mark groups is a mark group for generating a tracking servo tracking signal,
The plurality of mark groups are discretely arranged along the track direction at an arrangement interval equal to or less than a distance at which the tracking servo can operate in a predetermined band.
The plurality of mark groups are arranged so as not to be adjacent to each other along the radial direction so that the light beams are not simultaneously irradiated based on a beam diameter of the tracking servo light beam. The recording medium according to claim 1.
The plurality of mark groups are mark groups for carrying address information indicating address positions from the inner periphery to the outer periphery or from the outer periphery to the inner periphery along the track direction. recoding media.
A recording / reproducing apparatus that performs at least one of a recording process and a reproducing process for the recording medium according to claim 1,
A light irradiating means for irradiating and condensing the guide layer with a guide laser beam, and irradiating and condensing a recording / reproducing laser beam different from the guide laser beam to one of the plurality of recording layers;
First control means for controlling the light irradiation means to perform tracking control for applying tracking servo to the guide track in a predetermined band based on the return light of the guide laser light from the guide layer;
In the state in which the tracking servo is applied, the recording / reproducing laser light is irradiated on and condensed on the one recording layer, so that at least one of the recording process and the reproducing process is performed. And a second control means for controlling the irradiation means.
2. A recording / reproducing laser that irradiates and condenses guide laser light to the guide layer according to claim 1 and that is different from the guide laser light on one of the plurality of recording layers. A recording / reproducing method for performing at least one of a recording process and a reproducing process using a light irradiating means that irradiates and collects light,
A first control step of controlling the light irradiation means so as to perform tracking control for applying tracking servo to the guide track in a predetermined band based on the return light of the guide laser light from the guide layer;
In the state in which the tracking servo is applied, the recording / reproducing laser light is irradiated on and condensed on the one recording layer, so that at least one of the recording process and the reproducing process is performed. And a second control step for controlling the irradiation means.