WO2014199468A1

WO2014199468A1 - Information recording/reproduction device and method

Info

Publication number: WO2014199468A1
Application number: PCT/JP2013/066250
Authority: WO
Inventors: 琢也白戸; 吉田　昌義; 田切　孝夫
Original assignee: パイオニア株式会社
Priority date: 2013-06-12
Filing date: 2013-06-12
Publication date: 2014-12-18

Abstract

This information recording/reproduction device (101) records information onto or reproduces recorded information from a recording medium that has the following: a guide layer (12) that has a single-spiral guide track; and a plurality of recording layers (13). In said recording medium, a switchover region in which land tracks and group tracks switch comprises a first region in which pits and spaces having the same rotational-phase position are laid out radially in a periodic fashion with a first period and a second region in which pits and spaces having the same rotational-phase position are laid out radially in a periodic fashion with a second period. Both the first period and the second period are smaller than the spot diameter of a guide beam shone on the guide layer. This information recording/reproduction device is provided with a first-region detection means (540) that detects the first region, a second-region detection means (550) that detects the second region, and a switchover-region detection means (560) that detects the switchover region on the basis of the results of the first-region detection and/or the second-region detection.

Description

Information recording / reproducing apparatus and method

The present invention relates to a technical field of an information recording / reproducing apparatus and method for recording information on a recording medium such as an optical disc including a large number of recording layers and guide layers, or reproducing the recorded information.

As a recording medium in which this type of information recording / reproducing apparatus is used, for example, a multi-layer optical disc (so-called guide layer separation) having a plurality of recording layers on which data is recorded and a guide layer on which a tracking guide track is recorded. Type multilayer optical disk) is known. When recording on a guide layer-separated type multilayer optical disc, for example, a tracking servo light beam (hereinafter referred to as a guide beam or guide laser light) is applied to the guide layer to perform tracking control, and recording / reproduction is performed on the recording layer. Recording is performed by irradiating a light beam (hereinafter, recording beam, recording / reproducing laser beam).

On the other hand, a single spiral land / groove structure is known as a structure of a guide track provided on an optical disc (see, for example, Patent Document 1). An optical disc having such a structure has a switching area in which a land track and a groove track are switched every round of the disc (see, for example, Patent Documents 2 to 4). When an optical disk having a single spiral land / groove structure is used, it is required to reliably detect the switching area described above. Note that it is preferable that the switching region can be detected not only after the tracking servo is closed but also in an open state. This is because there is an effect that it becomes possible to avoid the switching area when the tracking servo is pulled in to shift to the closed state.

Japanese Patent No. 2890443 Japanese Patent No. 2684969 Japanese Patent No. 3059026 Japanese Patent No. 3092510

In a guide layer separation type multi-layer optical disk system, the spot diameter of a guide beam (typically a red laser beam for DVD) on the guide layer is larger than the track pitch corresponding to the blue laser beam for recording and reproduction. Therefore, there is a technical problem that multiple tracks are read simultaneously. There is also a technical problem that the state of aberration generated in the guide beam differs depending on which recording layer the recording beam is focused on. In addition, there is a technical problem that defocusing occurs in the guide beam due to variations in the disc thickness (that is, the distance between the guide layer and the recording layer).

Therefore, when the single spiral land / groove structure and the land / groove switching region as described in Patent Documents 1 to 4 described above are employed in the guide layer of the guide layer separation type multi-layer optical disc, any countermeasure is temporarily taken. Otherwise, various problems may occur.

The present invention has been made in view of, for example, the above-described technical problems, and an object thereof is to provide an information recording / reproducing apparatus and method capable of suitably detecting a land / groove switching area in a recording medium.

In order to solve the above problems, an information recording / reproducing apparatus of the present invention includes a guide layer in which a guide track for tracking is formed, and a plurality of recording layers stacked on the guide layer. The land track and the groove track of the groove structure are alternately arranged in a single spiral track, and a switching region for switching the land track and the groove track is formed at a predetermined rotational phase position of the guide layer. The switching area includes a first area in which pits and spaces are periodically arranged in the radial direction at a first period at the same rotational phase position, and the pits and the space are radiused at the same rotational phase position. A second region periodically disposed in a second period different from the first period in the direction, An information recording / reproducing apparatus for recording information on a recording medium or reproducing recorded information, wherein the period and the second period are smaller than a spot diameter of a guide beam irradiated on the guide layer. The first region detecting means for detecting the first region, the second region detecting means for detecting the second region, and the switching based on at least one of the detection results of the first region and the second region. Switching area detecting means for detecting the area.

In order to solve the above problems, an information recording / reproducing method of the present invention includes a guide layer in which a guide track for tracking is formed, and a plurality of recording layers stacked on the guide layer. The land track and the groove track of the groove structure are alternately arranged in a single spiral track, and a switching region for switching the land track and the groove track is formed at a predetermined rotational phase position of the guide layer. The switching area includes a first area in which pits and spaces are periodically arranged in the radial direction at a first period at the same rotational phase position, and the pits and the space are radiused at the same rotational phase position. A second region periodically disposed in a second period different from the first period in the direction, An information recording / reproducing method for recording information on a recording medium or reproducing recorded information, wherein the period and the second period are smaller than a spot diameter of a guide beam irradiated on the guide layer. The switching is performed based on at least one of a first region detecting step for detecting the first region, a second region detecting step for detecting the second region, and a detection result of the first region and the second region. A switching area detecting step for detecting an area.

The operation and other gains of the present invention will be described together with embodiments for carrying out the invention described below.

It is a block diagram which shows the whole structure of the information recording / reproducing apparatus based on an Example. It is a conceptual diagram which shows the structure of an optical pick-up with the various signals detected. A schematic perspective view that makes each layer easy to see by disassembling a plurality of layers constituting a single guide layer-separated multilayer optical disc at intervals in the stacking direction (vertical direction in FIG. 3). FIG. It is a top view which shows the structure of a single spiral land / groove structure with the enlarged view of a switching area | region and its front-and-back part. It is a top view which shows the structure of the switching area | region in the guide layer separation type | mold multilayer optical disc based on an Example. The tangential push-pull signal obtained from the switching region of the guide layer when the recording / reproducing laser beam is focused on the L5 layer and the focus of the guide laser beam is adjusted so that the tracking error signal amplitude from the guide layer becomes substantially maximum. It is a graph which shows the example of a waveform. FIG. 7 is a graph showing an example of a waveform of a tangential push-pull signal obtained from the switching region of the guide layer when the guide laser beam of about 2 μm is defocused from the state where the waveform of FIG. 6 is obtained. The tangential push-pull signal obtained from the switching region of the guide layer when the recording / reproducing laser beam is focused on the L0 layer and the focus of the guide laser beam is adjusted so that the tracking error signal amplitude from the guide layer becomes substantially maximum. It is a graph which shows the example of a waveform. FIG. 9 is a graph showing an example of a waveform of a tangential push-pull signal obtained from the switching region of the guide layer when the about 2 μm guide laser beam is defocused from the state where the waveform of FIG. 8 is obtained. It is a top view which shows the structure of the switching area | region in the guide layer of the guide layer separation type | mold multilayer optical disk which concerns on a comparative example. FIG. 11 is a plan view (No. 1) showing a configuration of a switching region in a guide layer of a guide layer separation type multilayer optical disc according to a modification. FIG. 11 is a plan view (No. 2) showing a configuration of a switching region in a guide layer of a guide layer separation type multilayer optical disc according to a modification. It is a flowchart which shows operation | movement of the information recording / reproducing apparatus based on an Example. It is a flowchart which shows the new disc recording process based on an Example. It is a flowchart which shows the new disc reproduction | regeneration processing based on an Example. It is a block diagram which shows the structure of the switching area | region detection part of the information recording / reproducing apparatus based on an Example. It is a conceptual diagram which shows the detection method of the peak of a tangential push pull signal. It is the conceptual diagram (the 1) which shows the detection method of the switching area by the information recording / reproducing apparatus based on an Example with the structure of a switching area, and the waveform of a tangential push pull signal. It is the conceptual diagram (the 2) which shows the detection method of the switching area by the information recording / reproducing apparatus based on an Example with the structure of a switching area, and the waveform of a tangential push pull signal. FIG. 12 is a conceptual diagram (part 3) illustrating the method of detecting the switching area by the information recording / reproducing apparatus according to the embodiment, together with the configuration of the switching area and the waveform of the tangential push-pull signal. FIG. 12 is a conceptual diagram (part 4) illustrating the method of detecting the switching area by the information recording / reproducing apparatus according to the embodiment, together with the configuration of the switching area and the waveform of the tangential push-pull signal. It is a block diagram which shows the structure of the switching area | region detection part of the information recording / reproducing apparatus which concerns on a modification. It is a conceptual diagram which shows the detection method of the switching area | region by the information recording / reproducing apparatus which concerns on a modification.

The information recording / reproducing apparatus according to the present embodiment includes a guide layer in which a guide track for tracking is formed, and a plurality of recording layers stacked on the guide layer, and the guide track is a land having a land structure. A single spiral track in which a track and a groove track having a groove structure are alternately arranged, and a switching region for switching the land track and the groove track is formed at a predetermined rotational phase position of the guide layer, The switching region includes a first region in which pits and spaces are periodically arranged in the radial direction at a first rotational phase position at the same rotational phase position, and the first pit and the space in the radial direction at the same rotational phase position. A second region periodically arranged at a second period different from the period, the first period and the first An information recording / reproducing apparatus for recording information on a recording medium or reproducing recorded information, wherein the period is smaller than a spot diameter of a guide beam irradiated on the guide layer, wherein the first area A first area detecting means for detecting the second area, a second area detecting means for detecting the second area, and a switch for detecting the switching area based on at least one of the detection results of the first area and the second area. Region detecting means.

A recording medium on / from which information is recorded / reproduced by the information recording / reproducing apparatus according to the present embodiment includes a guide layer on which a guide track having a guide structure is formed, and a plurality of recording layers stacked on the guide layer. It is a multilayer optical disk. In the recording medium, the guide track of the guide layer is a single spiral track in which land tracks having a land structure and groove tracks having a groove structure are alternately arranged. That is, the guide track according to the present embodiment has a so-called single spiral land / groove structure.

A switching region for switching between land tracks and groove tracks is formed at a predetermined rotational phase position of the guide layer. The switching region has a first region in which pits and spaces are periodically arranged in the radial direction at a first period at the same rotational phase position. Furthermore, the switching area has a second area in which pits and spaces are periodically arranged in the radial direction at a second period at the same rotational phase position. Here, the “first period” and the “second period” are predetermined periods set in advance and are different from each other. That is, the switching area according to the present embodiment has two areas in which pits and spaces are arranged in the radial direction at different periods. In addition, the switching region is set so that the first period and the second period are smaller than the spot diameter of the guide beam irradiated to the guide layer.

At the time of recording / reproducing by the information recording / reproducing apparatus according to the present embodiment, the guide layer of the recording medium is irradiated with a tracking guide beam via an objective lens to perform tracking control, and each of the plurality of recording layers is subjected to an objective. A recording beam for recording / reproduction is irradiated through the lens. In addition, in the information recording / reproducing apparatus according to the present embodiment, the switching area is detected particularly during recording / reproduction.

When detecting the switching area, first, the first area is detected by the first area detecting means, and the second area is detected by the second area detecting means. Specifically, the first area detecting means and the second area detecting means receive a signal obtained by receiving and calculating a reflected light obtained by irradiating the guide layer with a tracking guide beam (hereinafter referred to as “detection appropriately”). The first region and the second region are detected based on the “signal”. An example of the detection signal is a tangential push-pull signal.

Here, in the first region and the second region described above, detection signals are obtained in different states according to the difference in the period of each pit and space. For example, the waveform of the detection signal obtained in the first region (that is, the waveform used for detection in the first region detection means) has a shape corresponding to the first period, and the waveform of the detection signal obtained in the second region ( That is, the waveform used for detection in the second region detection means has a shape corresponding to the second period. (The shape here includes not only amplitude but also distortion.) For this reason, for example, a waveform having a relatively small amplitude may be obtained in the first region, and a waveform having a relatively large amplitude may be obtained in the second region. . In addition, a waveform having a relatively large amplitude may be obtained in the first region, and a waveform having a relatively small amplitude may be obtained in the second region. In addition, a waveform with relatively large distortion and difficult peak detection may be obtained in the first region, and a waveform with relatively small distortion and easy peak detection may be obtained in the second region. In addition, a waveform with relatively small distortion and easy peak detection may be obtained in the first region, and a waveform with relatively large distortion and difficult peak detection may be obtained in the second region.

Further, the first period of the first region and the second period of the second region are set to be smaller than the spot diameter of the guide beam irradiated to the guide layer as described above. For this reason, at the time of detection of the first region and the second region, at least a plurality of pits and spaces are included in the spot of the guide beam. Therefore, a stable detection signal can be obtained regardless of the radial position through which the beam spot passes, and the first region and the second region can be detected more easily. For example, it is possible to detect the switching area not only when the tracking servo is closed but also when the tracking servo is open.

When the detection of the first area and the second area is executed, the switching area is detected based on the detection results. Specifically, the switching area detecting means detects the switching area based on at least one of the detection results of the first area and the second area. For example, when both the first area and the second area are detected, when only the first area is detected, or when only the second area is detected, it is determined that this is the switching area. .

Here, in particular, if two types of detection signals are obtained in the first region and the second region, for example, even if it is not possible to detect whether or not it is a switching region with only one detection signal, the other detection is performed. There is a possibility that it is possible to detect whether or not it is a switching area by using a business signal. That is, since two types of detection signals are obtained, the possibility that the switching area can be detected can be increased accordingly. Therefore, for example, even when aberration, defocus, or the like occurs in the tracking guide beam, the switching region can be detected suitably.

As described above, according to the information recording / reproducing apparatus according to the present embodiment, the land / groove switching area in the guide layer is preferably detected by detecting two types of areas, the first area and the second area. Is possible.

In one aspect of the information recording / reproducing apparatus according to the present embodiment, in at least one of the first area and the second area in the recording medium, the pits and the spaces are periodically arranged in a track direction at a predetermined period. And at least one of the first region detection unit and the second region detection unit is configured to detect the first region based on a peak interval in a predetermined period of the detection signal obtained from the first region or the second region. Alternatively, the second region is detected.

According to this aspect, in at least one of the first region and the second region, the pits and spaces are periodically arranged not only in the radial direction but also in the track direction. When pits and spaces are periodically arranged in the track direction as described above, the detection signal is detected as a signal having a peak at a predetermined period. In addition, regarding the period in the track direction, unlike the period in the radial direction, the first area and the second area may not have different periods.

At least one of the first region detection unit and the second region detection unit detects the first region or the second region based on a peak interval in a predetermined period of the detection signal obtained from the first region or the second region. . For example, the first area detecting means and the second area detecting means compare the peak interval of the detection signal with a predetermined period that is the interval between the pits and the space in the track direction, and when they match, The first region or the second region is detected. In this way, it is possible to detect the first region and the second region easily and accurately.

In the aspect in which the first region and the second region are detected based on the above-described peak interval, at least one of the first region detection unit and the second region detection unit has the peak interval that is a predetermined number of times and the predetermined period. The first area or the second area may be detected when the two coincide with each other.

In this case, even if the peak interval coincides with the predetermined period, the first region or the second region is not detected if the number of continuous coincidence is equal to or less than the predetermined number. Therefore, erroneous detection of the first region and the second region can be reduced. The “predetermined number of times” is calculated and set in advance theoretically, experimentally, or empirically as the number of times that the first region or the second region can be accurately detected.

In the aspect in which the first region and the second region are detected when the above-described peak interval coincides continuously a predetermined number of times, at least one of the first region detection unit and the second region detection unit has a positive electrode as the peak interval. When the positive-side peak interval and the negative-side peak interval are detected, and both the positive-side peak interval and the negative-side peak interval coincide with the predetermined period continuously for the predetermined number of times, The first area or the second area may be detected.

In this case, in order to detect the first region or the second region, it is required that both the peak interval on the positive polarity side and the peak interval on the negative polarity side coincide with a predetermined cycle continuously a predetermined number of times. Therefore, the first region and the second region can be detected more accurately.

Alternatively, in the aspect in which the first region and the second region are detected when the peak interval coincides a predetermined number of times, at least one of the first region detection unit and the second region detection unit has a positive polarity as the peak interval. When the peak interval on the side and the peak interval on the negative polarity side are detected, and either one of the peak interval on the positive polarity side or the peak interval on the negative polarity side coincides with the predetermined cycle continuously for the predetermined number of times, The first area or the second area may be detected.

In this case, in order to detect the first region or the second region, one of the positive-polarity peak interval and the negative-polarity peak interval may coincide with a predetermined cycle continuously a predetermined number of times. Therefore, for example, even if one of the positive polarity side peak and the negative polarity side peak cannot be detected, the first region and the second region can be reliably detected.

In another aspect of the information recording / reproducing apparatus according to the present embodiment, at least one of the first area detecting means and the second area detecting means has the tracking servo opened and the first area or the second area is To detect.

The tracking servo is required to switch the polarity of the tracking error signal in the closed state depending on whether the track being traced is a land track or a groove track. Therefore, it is not preferable to shift the tracking servo from the open state to the closed state in the switching region.

In contrast, in this embodiment, as described above, the first period of the first region and the second period of the second region are set to be smaller than the spot diameter of the guide beam irradiated on the guide layer. Therefore, a stable detection signal can be obtained regardless of the radial position of the beam spot, and the first region or the second region can be detected with the tracking servo open. Therefore, the tracking servo can be shifted from the open state to the closed state while avoiding the switching region.

The information recording / reproducing method according to the present embodiment includes a guide layer on which a tracking guide track is formed, and a plurality of recording layers stacked on the guide layer, and the guide track includes a land structure land. A single spiral track in which a track and a groove track having a groove structure are alternately arranged, and a switching region for switching the land track and the groove track is formed at a predetermined rotational phase position of the guide layer, The switching region includes a first region in which pits and spaces are periodically arranged in the radial direction at a first rotational phase position at the same rotational phase position, and the first pit and the space in the radial direction at the same rotational phase position. A second region periodically arranged at a second period different from the period, the first period and the first An information recording / reproducing method for recording information on a recording medium or reproducing recorded information, wherein the period is smaller than a spot diameter of a guide beam irradiated on the guide layer, wherein the first area A first region detecting step for detecting the second region, a second region detecting step for detecting the second region, and a switching for detecting the switching region based on at least one of the detection results of the first region and the second region. A region detecting step.

According to the information recording / reproducing method according to the present embodiment, the land in the guide layer is detected by detecting two types of areas, the first area and the second area, as in the information recording / reproducing apparatus according to the present embodiment described above. / It is possible to detect suitably the switching area of the groove.

In the information recording / reproducing method according to the present embodiment, the same aspects as various aspects that can be adopted by the information recording / reproducing apparatus according to the above-described embodiment can be adopted.

The operation and other gains of the information recording / reproducing apparatus and method according to this embodiment will be described in more detail in the following examples.

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

<Configuration of information recording / reproducing apparatus>
First, the configuration of the information recording / reproducing apparatus 101 will be described with reference to FIG. FIG. 1 is a block diagram showing the overall configuration of the information recording / reproducing apparatus according to the embodiment. FIG. 2 is a conceptual diagram showing various signals for obtaining the configuration of the optical receiver of the optical pickup.

In FIG. 1, an information recording / reproducing apparatus 101 is configured as a disk drive and connected to a host computer 201. The recording / reproducing apparatus 101 includes an optical pickup 102, a signal recording / reproducing unit 103, a spindle motor 104, a tilt correction mechanism 105, a bus 106, a CPU (drive control unit) 111, a memory 112, and a data input / output control unit 113. Has been.

The host computer 201 includes an operation / display control unit 202, operation buttons 203, a display panel 204, a bus 206, a CPU 211, a memory 212, and a data input / output control unit 213.

When information is recorded by the information recording / reproducing apparatus 101, data to be recorded is input from the data input / output control unit 213 in the host computer 201 to the information recording / reproducing apparatus 101. During reproduction, the reproduced data is output from the data input / output control unit 213 in the host computer 201.

The optical pickup 102 in the information recording / reproducing apparatus 101 is composed of a separation / separation optical system including a red semiconductor laser that emits a guide laser beam LB1, a blue semiconductor laser that emits a recording / reproduction laser beam LB2, a prism, a mirror, and the like including an objective lens. System. The optical pickup 102 is configured to irradiate the guide laser beam LB1 and the recording / reproducing laser beam LB2 coaxially and with different focus via a common objective lens.

The optical pickup 102 is provided with a tilt correction mechanism 105. The tilt correction mechanism 105 corrects the tilt of the objective lens in the optical pickup 102 in accordance with a control signal from the signal recording / reproducing unit 103.

As shown in FIG. 2, the optical pickup 102 includes a light receiving element such as a quadrant CCD that receives reflected light from the optical disk 11 caused by the guide laser light LB1, and an optical disk 11 caused by the recording / reproducing laser light LB2. And a light receiving element such as a quadrant CCD that receives the reflected light. The optical pickup 102 and the signal recording / reproducing unit 103 can generate, for example, a radial push-pull signal, a tangential push-pull signal, and an RF signal by a light receiving signal from a light receiving element that receives reflected light from the guide layer 12 at least during recording. It is configured.

<Configuration of recording medium>
Next, with reference to FIG. 3 and FIG. 4, the configuration of the guide layer separation type multilayer optical disc 11 which is a specific example of the “recording medium” will be described. Here, FIG. 3 shows that a plurality of layers constituting a single guide layer separation type multilayer optical disc are disassembled at intervals in the stacking direction (vertical direction in FIG. 3), thereby making each layer easy to see. It is a typical perspective view formed. FIG. 4 is a plan view showing the structure of the guide layer 12 having a single spiral land / groove structure together with a partially enlarged view of a land / groove switching region.

As shown in FIG. 3, the guide layer separation type multilayer optical disc 11 includes a single guide layer 12 and one or more recording layers 13.

When a recording operation (particularly, a recording operation on a desired recording layer 13) is performed on the guide layer separation type multilayer optical disc 11, a tracking guide laser beam LB1 focused on the guide layer 12 and a plurality of recording layers The recording / reproducing laser beam LB2 condensed on each of the 13 is irradiated from the recording / reproducing apparatus 100 at the same time. On the other hand, when a reproducing operation for the guide layer separation type multilayer optical disc 11 (particularly, a reproducing operation for a desired recording layer 13) is performed, the guide laser beam LB1 and the recording / reproducing laser beam LB2 are also recorded on the recording / reproducing apparatus 100. From the same time. However, when a reproducing operation is performed on the optical disc 11, the recording / reproducing laser beam LB2 may be used for tracking (that is, the guide laser beam LB1 may not be used).

As shown in FIG. 3, the recording / reproducing laser beam LB2 is focused on one desired recording layer 13 to be recorded or reproduced among one or more 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, for example, like BD (Blu-ray (registered trademark) 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 one or more recording layers 13 is a recording layer capable of optically recording and reproducing recording information independently. More specifically, each of the one or more recording layers 13 is composed of a translucent thin film containing a two-photon absorption material, for example. 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.

As shown in FIG. 4, the guide layer 12 of the guide layer separation type multilayer optical disk 11 has a single spiral land / groove structure. Specifically, the groove track GT is switched to the land track LT in a predetermined switching area 300 of the guide layer 12. Similarly, the land track LT is switched to the groove track GT in a predetermined switching area 300 of the guide layer 12. As a result, the groove track GT and the land track LT form a single spiral when viewed from the entire guide layer 12.

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.

<Configuration of switching area>
Next, the configuration of the switching region 300 in the guide layer 12 of the guide layer separation type multilayer optical disc 11 will be described with reference to FIG. FIG. 5 is a plan view showing the configuration of the switching region 301 in the guide layer of the guide layer separation type multilayer optical disc 11 according to the first embodiment.

As shown in FIG. 5, the switching region 201 in the guide layer 12 of the guide layer separation type multilayer optical disc 11 according to the present embodiment has a first region 310 and a second region 320 that are adjacent to each other in the track direction of the disc. Yes.

In the first area 310, pits PT1 and spaces SP1 are arranged at a predetermined first period in the radial direction of the disc. The pit PT1 and the space SP1 are also periodically arranged in the track direction of the disk.

On the other hand, in the second region 320, pits PT2 and spaces SP2 are arranged in a predetermined second period in the radial direction of the disc. The pit PT2 and the space SP2 are also periodically arranged in the track direction of the disk.

Here, in particular, as can be seen from the figure, the first period which is the period in the radial direction of the pits PT1 and the space SP1 in the first area 310, and the period in the radial direction of the pits PT2 and the space SP2 in the second area 320. Are different from each other (more specifically, the second period is longer than the first period). That is, the first region 310 and the second region 320 are intentionally formed as different regions.

Also, the first period and the second period are smaller than the beam spot BS of the guide beam. That is, the sum of the widths of the pit PT1 and the space SP1 in the track direction and the sum of the widths of the pit PT2 and the space SP2 in the track direction are smaller than the width of the beam spot BS in the track direction.

By configuring the switching area 301 in this manner, for example, when data is recorded on the guide layer separation type multilayer optical disc 11, the switching area 301 can be suitably detected.

Here, the problem of guide beam defocusing and aberration existing in the guide layer separation type multilayer optical disk system will be described.

In the guide layer separation type multi-layer optical disk system, the recording / reproducing laser beam LB2 follows the focus of the recording layer to be recorded / reproduced by the focus servo, but the tracking error signal amplitude obtained from the guide layer 12 becomes substantially maximum for the guide laser beam LB1. Thus, the beam expander is adjusted, and recording / reproduction is performed in a state where the focus is statically approximately adjusted (not dynamically following) with respect to the guide layer. Therefore, the focus state of the guide laser beam LB1 with respect to the guide layer 12 is indefinite (although it is roughly matched). Furthermore, the distance between the guide layer and the recording layer varies depending on the position in the disk surface due to the variation in the thickness of the guide layer and the recording layer or the intermediate layer between the recording layer and the recording layer. Join as a focus.

The optical system for the guide laser beam LB1 can only be designed to minimize the aberration of the guide laser LB1 when the recording / reproducing laser beam LB2 is focused on a certain recording layer, and a special aberration correction device is prepared. Unless otherwise, the guide laser beam LB1 has different aberrations depending on which recording layer the recording / reproducing laser beam LB2 is focused on.

As described above, when information (for example, the switching region 201) formed on the guide layer 12 is read with the guide laser beam LB1, the defocus state is indefinite and the amount of aberration is also on the recording layer that focuses the recording / reproducing laser beam LB2. It will be read in a situation where it changes accordingly.

Hereinafter, effects obtained by the switching area 201 described above will be described with reference to FIGS. 5 and 6.

For detection of the switching region 201, a tangential push-pull signal obtained by irradiating the guide layer 12 with the guide laser beam LB1 is used. Specifically, for example, the period of the acquired tangential push-pull signal (detects a peak exceeding a set threshold and regards the peak interval as the period) in the first area 310 or the second area 320. It is determined whether or not it corresponds, and when it is determined that the area corresponds to the first area 310 or the second area 320, the switching area 201 is detected.

In FIG. 6, the recording laser beam LB2 is focused on the recording layer L5 (that is, the recording layer 13 located at the sixth position from the guide layer 12 side), and the tracking error signal amplitude obtained from the guide layer is substantially maximum. This is an example of a tangential push-pull signal waveform obtained from the switching region 201 when the focus adjustment of the guide laser beam LB1 is manually performed. An ideal waveform with less distortion is obtained from both the first region 310 and the second region 320, and the signal amplitude from the first region is relatively large, while the signal amplitude from the second region 320 is It is moderate.

FIG. 7 is an example of a tangential push-pull signal waveform obtained from the switching region 201 when the guide laser beam LB1 is intentionally defocused by about 2 μm from the state of FIG. The signal amplitude obtained from the first region 310 is slightly smaller than that in FIG. Further, the signal obtained from the second region 320 is distorted as compared to FIG.

In FIG. 8, the recording laser beam LB2 is focused on the recording layer L0 (that is, the first recording layer 13 counted from the guide layer 12 side), and the tracking error signal amplitude from the guide layer becomes substantially maximum. FIG. 6 is an example of a tangential push-pull signal waveform obtained from the switching area 201 when the focus is manually adjusted as described above. In the system in which this waveform is measured, by design, when the recording / reproducing laser beam LB2 is focused on the L0 layer among the plurality of recording layers 13, the aberration generated in the guide laser beam LB1 is the largest. The waveform obtained from the first region 310 has a relatively small amplitude, and the negative peak is hardly visible due to distortion. On the other hand, the waveform obtained from the second region 320 has a relatively large amplitude although it differs from an ideal differential waveform due to distortion.

FIG. 9 is an example of a tangential push-pull signal waveform obtained from the switching region 201 when the guide laser beam LB1 is intentionally defocused by about 2 μm from the state of FIG. The waveform obtained from the first region 310 has a medium amplitude. On the other hand, the waveform obtained from the second region 320 has a relatively large amplitude. Both are less distorted. As described above, the amplitude and distortion of the tangential push-pull signal waveform obtained from the switching region 201 of the guide layer 12 are focused on which recording layer the focus state of the guide laser beam LB1 and the recording / reproducing laser beam LB2 are focused on. (That is, the aberration generated in the guide laser beam LB1). For this reason, if only one type of tangential push-pull signal can be obtained in the switching area 301, it may be difficult to determine whether or not the switching area 301 is present due to the fluctuation. That is, there is a possibility that the switching area 301 cannot be detected depending on conditions. For example, in the case of the waveform of FIG. 8 described above, if only the tangential push-pull signal obtained from the first region 310 can be used, the amplitude is small and the negative peak is hardly visible due to distortion. It is difficult to determine that the period is the corresponding period.

However, in the guide layer separation type multilayer optical disc 11 according to the present embodiment, the switching area 301 has two areas of the first area 310 and the second area 320 as described above. Therefore, two types of periodic tangential push-pull signals having different amplitudes and distortions can be obtained from the first region 310 and the second region 320. As shown in FIGS. 6 and 7, even if the focus state and aberration of the guide laser beam LB1 change, two types of periodic tangential push-pull signals can be acquired in each case. Therefore, even if the amplitude of one of the two types of tangential push-pull signals is very small or the peak detection is difficult due to waveform distortion, the switching region 301 is detected if the peak can be detected by the other tangential push-pull signal. Therefore, the switching area 301 can be detected more reliably.

<Comparison example of switching area>
Here, the operational effects of the switching region 301 described above will be described more specifically by comparison with the comparative example shown in FIG. FIG. 10 is a plan view showing the configuration of the switching area 301b in the optical disc according to the comparative example.

As shown in FIG. 10, in the switching area 301b according to the comparative example, the pits PT1b in the first area 310 are arranged at different periods for each track in the track direction. For this reason, the position of the edge of the pit (boundary changing from pit to space or from space to pit) when viewed in the track direction differs from track to track. In such a case, the waveform of the tangential push-pull signal acquired at the beam spot BS over a plurality of tracks fluctuates irregularly. Therefore, it becomes difficult to detect the switching area 301b from the tangential push-pull signal.

On the other hand, in the switching area 301 according to the first embodiment described above, the edges of the pits PT1 and PT2 are aligned in each track (see FIG. 5). For this reason, even if it acquires with the beam spot over a several track | truck, the periodic tangential push pull signal as shown in FIG.6 and FIG.7 is obtained, and it becomes possible to detect the switching area | region 301 suitably.

In the switching region 301b according to the comparative example, the pits PT2b in the second region 320 are arranged with a relatively large period T in the radial direction. As can be seen from the figure, this period T is larger than the diameter of the beam spot BS. In such a case, the waveform of the tangential push-pull signal varies greatly depending on the position of the beam spot BS in the radial direction (for example, the position of the beam spot in the track direction near the center of the track group where no pit exists). The tangential push-pull signal is almost zero). For this reason, it is difficult to stably detect the switching region 301b depending on the radial position through which the beam spot passes.

On the other hand, in the switching region 301 according to the first embodiment, the pits PT1 and PT2 and the spaces SP1 and SP2 are arranged in a radial direction with a period smaller than the diameter of the beam spot BS. For this reason, even if the radial position of the beam spot BS changes (because the ratio of marks included in the beam spot does not change greatly when viewed in the radial direction), the tangential push-pull signal The waveform does not fluctuate greatly. Therefore, detection of the switching area 301 independent of the position of the beam spot BS can be realized. In this case, for example, detection with the tracking servo opened is also possible.

<Modification of switching area>
Next, the switching

areas

302 and 303 in the guide layer separation type multilayer optical disc 11 according to the modification will be described with reference to FIGS. 11 and 12. Here, FIGS. 11 and 12 are plan views showing the configurations of the switching

regions

302 and 303 in the guide layer separation type multilayer optical disc 11 according to the modification, respectively.

As shown in FIG. 11, in the first region 310 in the switching region 302 according to one modification, the pits PT3 are arranged so as to be continuously connected in the radial direction of the disc. In other words, in the first region 310, pits PT3 having a predetermined width in the radial direction and zero-width spaces are periodically arranged at a predetermined cycle. The pits PT3 in the first region 310 are periodically arranged with respect to the track direction of the optical disc 11 with the space SP3 interposed therebetween.

On the other hand, in the second area 320, the pits PT4 and the spaces SP4 are arranged at a predetermined period in the radial direction and the track direction of the disc. That is, it is arranged similarly to the switching area 301 according to the first embodiment.

Note that the pit PT3 in the first region 310 can be handled as a pit having a predetermined width and a space having a zero width arranged in an arbitrary cycle as described above. For this reason, regardless of the period in the radial direction in the second region 320, the period in the radial direction of the first region 310 and the period in the radial direction of the second region 320 are different from each other. It can be said.

Here, the pit PT3 in the first region 310 described above is provided so as to be connected in the radial direction, so that substantially the same tangential push-pull signal is generated regardless of the radial position of the beam spot BS. can get. Therefore, the first region 310 can be detected suitably.

In the second area 320, a tangential push-pull signal different from that in the first area 310 is obtained. That is, in the switching area 302, two different types of tangential push-pull signals are obtained as in the switching area 301 according to the above-described embodiment. Therefore, it is possible to detect the switching region 302 more reliably.

As shown in FIG. 12, in the switching area 303 according to another modification, the pit PT5 and the space SP5 are arranged at a predetermined first period in the radial direction of the disc, and the pit PT6 and the space SP6 are arranged. The second regions 320 arranged in a predetermined second period (that is, a period different from the first period) in the radial direction of the disk are alternately arranged periodically in units of one column. That is, when viewed in the track direction, a plurality of first regions 310 and second regions 320 are alternately arranged.

According to the switching area 303 according to this modification, the tangential push-pull signal corresponding to the first area 310 and the tangential push-pull signal corresponding to the second area 320 are obtained alternately and periodically. That is, different tangential push-pull signals are obtained alternately and periodically. Therefore, it is possible to detect the switching area 303 suitably.

<Operation of Information Recording / Reproducing Device>
Next, the overall operation of the information recording / reproducing apparatus 101 according to the embodiment will be described with reference to FIG. FIG. 13 is a flowchart showing the operation of the information recording / reproducing apparatus in the embodiment.

First, the guide layer separation type multilayer optical disc 11 having the format according to the above-described embodiment is mounted on the recording / reproducing apparatus 101 by manual or mechanical operation by the user (step S101).

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 guide layer separation type multilayer optical disc 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 the tracking operation is started (step S102). Although not shown in FIG. 13, the servo system for the recording layer 13 is operated before the guide layer reading servo system is operated. That is, the recording / reproducing laser beam LB2 is irradiated and condensed on the recording layer 13, and the focusing operation is started.

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, disc management information recorded in advance on the guide layer separation type multilayer optical disc 11 is acquired by the CPU 111 on the drive side, the CPU 211 on the host side, or the like (step S103).

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

Next, the CPU 111 on the drive side or the CPU 211 on the host side determines whether the requested operation is data recording (step S104). Here, in the case of data recording (step S104: Yes), a recording process for the new guide layer separation type multilayer optical disc 11 is executed (step S105). This recording process will be described in detail later (see FIG. 14).
On the other hand, if it is not data recording in the determination in step S104 (step S104: No), or if the recording process for the new guide layer separation type multilayer optical disc 11 is completed in step S105, the CPU 111 on the drive side or the host side The CPU 211 or the like determines whether or not the requested operation is data reproduction (step S106). Here, in the case of data reproduction (step S106: Yes), reproduction processing for the new guide layer separation type multilayer optical disc 11 is executed (step S107). This reproduction process will be described later in detail (see FIG. 15).

If it is determined in step S106 that the data is not reproduced (step S106: No), or if the reproduction process for the new guide layer separation type multilayer optical disc 11 is completed in step S107, the ejection, that is, the ejection of the tray is performed. It is determined whether the request is made via the button 203 or the like (step S108). Here, if ejection is not requested (step S108: No), the process returns to step S104, and the subsequent steps are executed again.

On the other hand, if ejection is requested in the determination in step S108 (step S108: No), the ejection operation is executed (step S109), and a series of recording / reproducing processes for the guide layer separation type multilayer optical disc 11 is completed. .

Next, an example of a recording process (step S105 in FIG. 13) for the new guide layer separation type multilayer optical disc 11 will be described with reference to FIG.

In FIG. 14, when the recording process is started, first, the recording / reproducing laser beam LB2 is subjected to focus servo to a desired recording layer 13 on which data is to be recorded, under the control of the CPU 111 and the signal recording / reproducing unit 103. (Step S201).

Subsequently, the guide laser beam LB1 is focused on the guide layer 12 under the control of the CPU 111 and the signal recording / reproducing unit 103 (step S202). At this time, the focus is adjusted so that the amplitude of the tracking error signal obtained by irradiating the guide laser beam LB1 onto the guide layer 12 becomes substantially maximum.
.

Subsequently, the optical pickup 102 is controlled, and tracking servo is applied to the guide layer 12 (step S203).

Subsequently, address information on the track TR is acquired in the guide layer 12. By referring to this address information, the CPU 211 and the like search 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 the address position. By this search operation, the recording / reproducing laser beam LB2 having the optical system such as the objective lens in the optical pickup 102 in common with the guide laser beam LB1 is also within the recording surface corresponding to the searched recording address on the recording layer 13. It is moved to the plane position (step S204).
Subsequently, a recording synchronous clock, a recording start timing, and the like are generated based on a signal obtained from the guide layer 12 (step S205).

Subsequently, it is determined whether or not the current light spot has passed the recording start timing, that is, whether or not recording on the recording layer should be started (step S206).

Here, when the recording start timing is passed (step S206: Yes), recording on the desired recording layer 13 is started by the recording / reproducing laser beam LB2 (step S207).

After the recording is started, it is monitored by the CPU 111 or the like whether or not a predetermined amount of recording has been completed (step S208). Here, as long as the recording is not completed, the data recording to the recording layer 13 is continued (step S208: No).

When the recording is completed (step S208: Yes), the management information is updated according to the recorded data (step S209). The 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 management information provided in the memory 112, the memory 212, and the like and associated with the optical disc 11 may be updated.

As described above, a series of recording processes for the new guide layer separation type multilayer optical disc 11 is completed.

Next, an example of the reproduction process (step S17 in FIG. 29) for the new guide layer separation type multilayer optical disk 11 will be described with reference to FIG.

In FIG. 15, under the control of the CPU 111 and the signal recording / reproducing unit 103, the optical pickup 102 applies the focus servo of the recording / reproducing laser beam LB2 to the desired recording layer 13 from which data is to be reproduced. In parallel or in parallel, tracking servo is applied to the recorded information track by the recording / reproducing laser beam LB2 (step S301).

Subsequently, recorded address information on the recorded 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 the address position (step S302).

Subsequently, in a state where the tracking servo and the focus servo are closed by the optical pickup 102, the reflected light caused by the recording / reproducing laser beam LB2 is received through the objective lens, whereby the data from the desired recording layer 13 is received. Is started (step S303).

After the reproduction is started, it is monitored by the CPU 111 or the like whether or not the predetermined amount of reproduction has been completed (step S304). Here, as long as the reproduction is not completed, the reproduction of data from the recording layer 13 is continued (step 304: No).

When the reproduction is finished (step S304: Yes), a series of recording processes for the new optical disc 11 is completed.

As described above, the information recording / reproducing apparatus 101 according to the present embodiment can record information on the optical disc 11 and reproduce the recorded information. Here, since the optical disk 11 according to the present embodiment has a single spiral land / groove structure as described above, it is preferable that the switching area 300 in the guide layer 12 can be reliably detected during recording and reproduction.

The switching area 300 of the optical disc 11 according to the embodiment is already configured as shown in FIGS. 5, 11, 12, and the like, but in the following, for suitably detecting such a switching area 300 The operation will be described in detail.

<Detection of switching area>
First, the configuration of the switching area detection unit 500 that detects the switching area 300 of the optical disc 11 will be described with reference to FIGS. 16 and 17. FIG. 16 is a block diagram illustrating the configuration of the switching area detection unit of the information recording / reproducing apparatus according to the embodiment. FIG. 17 is a conceptual diagram showing a method for detecting the peak of the tangential push-pull signal.

As shown in FIG. 16, a tangential push-pull signal converted by the A / D converter 410 and having a predetermined band cut by the low-pass filter 420 is input to the switching area detection unit 500. The switching region detection unit 500 includes a peak detection unit 510, a peak interval counting unit 520, a period comparison unit 530, a first region determination unit 540, a second region determination unit 550, and a switching region detection signal generation unit 560. ing.

The peak detection unit 510 can detect the positive polarity side peak and the negative polarity side peak of the input tangential push-pull signal, respectively.

As shown in FIG. 17, the peak detection unit 510 detects the peak of the tangential push-pull signal using a predetermined threshold set in advance. Specifically, the peak detection unit 510 first calculates a time t _{r +} when the tangential push-pull signal becomes equal to or higher than a threshold TH + for detecting a peak on the positive polarity side, and a time t _{f +} when it becomes equal to or lower than the threshold TH +. To detect. Then, the peak detector 510 detects an intermediate value between the time _{tr +} and the time tf ₊ , that is, the time ( _tr ++ tf ₊ ) / 2 as a peak.

Here, only the case where the peak on the positive polarity side is detected is described here, but the peak can also be detected on the negative polarity side in the same manner.

As the peak detection method, various methods other than the above method are conceivable, and other methods may be used.

16, the peak interval counting unit 520 counts the intervals between the peaks based on the peaks detected by the peak detecting unit 510. Specifically, the peak interval counting unit 520 includes, for example, an interval T ++ from the positive polarity side peak to the next positive polarity side peak, an interval T ++ from the positive polarity side peak to the next negative polarity side peak, The interval T− + from the negative polarity side peak to the next positive polarity side peak and the interval T−− from the negative polarity side peak to the next negative polarity side peak are counted.

The period comparison unit 530 corresponds to the peak interval counted by the peak interval counting unit 520 and the period corresponding to each of the first region 310 and the second region 320 in the switching region 300 (that is, the period in the track direction of pits and spaces). Are compared with each other to determine whether or not they match within a predetermined error range.

In the determination by the period comparison unit 530, the first region determination unit 540 determines that the peak interval counted by the peak interval count unit 520 matches the period corresponding to the period of the pits and spaces in the first region 310. The first area 310 is detected. That is, it is determined that the tangential push-pull signal is obtained from the first region 310.

In the determination by the period comparison unit 530, the second region determination unit 550 determines that the peak interval counted by the peak interval count unit 520 matches the period corresponding to the period of the pits and spaces in the second region 320. The second area 320 is detected. That is, it is determined that the tangential push-pull signal is obtained from the second region 320.

The switching region detection signal generation unit 560 generates a switching region detection signal when at least one of the first region 310 and the second region 320 is detected in the first region determination unit 540 and the second region determination unit 550. And output. That is, if one of the first region 310 and the second region 320 is detected, the switching region 300 is detected even if the other is not detected.

Subsequently, the detection operation of the switching area 300 executed by the above-described switching area detection unit 500 will be described more specifically with reference to FIGS. 18 and 19. FIG. 18 and FIG. 19 are conceptual diagrams showing the switching area detection method by the information recording / reproducing apparatus according to the embodiment, together with the configuration of the switching area and the waveform of the tangential push-pull signal.

When a tangential push-pull signal as shown in FIG. 18 is obtained, the positive polarity side peak and the negative polarity side peak can be reliably detected by using the thresholds TH + and TH−. Therefore, it can be confirmed that the peak intervals T ++ 1, T + −1, T− + 1 and T−−1 coincide with the period of the pit PT1 and the space SP1 in the first region 310, and as a result, the first region 310 is detected. be able to. Similarly, it can be confirmed that the peak intervals T ++ 2, T + -2, T− + 2 and T−−2 coincide with the period of the pit PT2 and the space SP2 of the second region 320, and as a result, the second region 320 is detected. be able to. Thus, if both the 1st field 310 and the 2nd field 320 can be detected, switching field 300 can be detected reliably.

When the tangential push-pull signal as shown in FIG. 19 is obtained, the first region 310 detects the positive polarity side peak and the negative polarity side peak even if the threshold values TH + and TH− are used. I can't. For this reason, the peak intervals T ++ 1, T + -1, T- + 1 and T--1 cannot be detected, and as a result, the first region 310 cannot be detected.

However, in the second region 320, the positive side peak and the negative side peak can be reliably detected by using the threshold values TH + and TH−. For this reason, it can be confirmed that the peak intervals T ++ 2, T + -2, T− + 2 and T−−2 coincide with the period of the pit PT2 and the space SP2 of the second region 320, and as a result, the second region 320 is detected. be able to.

According to the switching area detection unit 500 according to the present embodiment, as described above, even if one of the first area 310 and the second area 320 cannot be detected, the other area can be detected. If there is, the switching area 300 can be detected.

In the examples so far, the first region 310 and the second region 320 are detected when the peaks of the tangential push-pull signal coincide on both the positive polarity side and the negative polarity side. The first region 310 and the second region 320 may be detected when the peak of the push-pull signal matches on either the positive polarity side or the negative polarity side.

Hereinafter, a method of detecting the first region 310 and the second region 320 only with one of the peaks will be described with reference to FIGS. 20 and 21. FIG. FIG. 20 and FIG. 21 are conceptual diagrams showing the switching area detection method by the information recording / reproducing apparatus according to the embodiment, together with the configuration of the switching area and the waveform of the tangential push-pull signal.

When the tangential push-pull signal as shown in FIG. 20 is obtained, only the positive polarity side peak can be detected in the first region 310 even if the threshold values TH + and TH− are used. For this reason, the detected peak interval is only T ++ 1. Even in such a case, according to the switching region detection unit 500 according to the present embodiment, if it can be confirmed that the peak interval T ++ 1 matches the period of the pit PT1 and the space SP1 of the first region 310, One region 310 can be detected.

On the other hand, in the second region 320, only the negative polarity side peak can be detected using the threshold values TH + and TH−. For this reason, the detected peak interval is only T--2. Even in such a case, according to the switching area detecting unit 500 according to the present embodiment, it is confirmed that the peak interval T--2 and the period of the pit PT2 and the space SP2 in the second area 320 are the same. If possible, the second region 320 can be detected.

According to the switching region detection unit 500 according to the present embodiment, as described above, even if one of the positive polarity side peak and the negative polarity side peak cannot be detected, the other peak can be detected. For example, the first region 310 and the second region 320 can be detected. Therefore, the switching area 300 can be detected.

When a tangential push-pull signal as shown in FIG. 21 is obtained, in the first region 310, two peaks are detected on the negative polarity side with respect to one peak on the positive polarity side. For this reason, normal detection cannot be performed for the negative polarity side peak, and the peak interval accurately detected is only T ++ 1 on the positive polarity side. Even in such a case, according to the switching region detection unit 500 according to the present embodiment, if it can be confirmed that the peak interval T ++ 1 matches the period of the pit PT1 and the space SP1 of the first region 310, One region 310 can be detected.

On the other hand, in the second region 320, two peaks are detected on the positive polarity side with respect to one peak on the negative polarity side. For this reason, the positive polarity side peak cannot be normally detected, and the accurately detected peak interval is only T--2 on the negative polarity side. Even in such a case, according to the switching area detecting unit 500 according to the present embodiment, it is confirmed that the peak interval T--2 and the period of the pit PT2 and the space SP2 in the second area 320 are the same. If possible, the second region 320 can be detected.

According to the switching region detection unit 500 according to the present embodiment, as described above, even if one of the positive polarity side peak and the negative polarity side peak cannot be detected normally, the other peak can be detected. If so, the first region 310 and the second region 320 can be detected respectively. Therefore, the switching area 300 can be detected.

In the example shown in FIGS. 20 and 21, both the first area 310 and the second area can be detected. However, as described with reference to FIG. 19, one of the first area 310 and the second area. Can be detected, the switching area 300 can be detected. Therefore, if any one of the positive polarity side peak and the negative polarity side peak can be accurately detected in either the first region 310 or the second region 320, the switching region 300 can be detected.

<Modification of switching area detector>
Next, a switching area detection unit 500b according to a modification will be described with reference to FIGS. FIG. 22 is a block diagram showing the configuration of the switching area detector of the information recording / reproducing apparatus according to the modification. FIG. 23 is a conceptual diagram showing a switching area detection method by the information recording / reproducing apparatus according to the modification.

As illustrated in FIG. 22, the switching region detection unit 500b according to the modification includes a peak detection / interval comparison unit 570 instead of the peak detection unit 510, the peak interval count unit 520, and the period comparison unit 530 (see FIG. 16). It is prepared for.

As shown in FIG. 23, when the peak detection / interval comparison unit 570 detects the first peak, a detection window is set at a predetermined period thereafter, and the presence of the peak in the detection window is detected. . The predetermined cycle is set to correspond to the cycle of the pits and spaces in the first region 310 or the second region 320 in the track direction. For this reason, if a peak is detected in the detection window, the peak interval automatically coincides with the peak interval of the first region 310 or the second region 320. As described above, the peak detection / interval comparison unit 570 can execute processing equivalent to executing all the processing in each of the peak detection unit 510, the peak interval counting unit 520, and the period comparison unit 530 alone. Therefore, also in the switching area detection unit 500b according to the modified example, it is possible to detect the switching area 300 suitably as in the switching area detection unit 500 according to the above-described embodiment.

The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and an information recording / reproducing apparatus with such a change And methods are also within the scope of the present invention.

DESCRIPTION OF SYMBOLS 11 Optical disk 12 Guide layer 13 Recording layer 101 Information recording / reproducing apparatus 102 Optical pick-up 103 Signal recording / reproducing part 113 Data input / output control part 201 Host computer 213 Data input / output control part 300 Switching area 310 1st area 320 2nd area 410 A / D converter 420 Low-pass filter 500 Switching region detection unit 510 Peak detection unit 520 Peak interval count unit 530 Period comparison unit 540 First region determination unit 550 Second region determination unit 560 Switching region detection signal generation unit 570 Peak detection / interval comparison unit BS Beam spot GT Groove track LT Land track LB1 Guide laser beam LB2 Recording / reproducing laser beam PT Pit SP Space

Claims

A guide layer in which a guide track for tracking is formed, and a plurality of recording layers stacked on the guide layer;
The guide track is a single spiral track in which land tracks having a land structure and groove tracks having a groove structure are alternately arranged,
A switching region for switching the land track and the groove track is formed at a predetermined rotational phase position of the guide layer,
The switching area is
A first region in which pits and spaces are periodically arranged at a first period in the radial direction at the same rotational phase position;
A second region in which the pits and the spaces are periodically arranged in a second period different from the first period in the radial direction at the same rotational phase position;
The information recording / reproducing apparatus for recording information on a recording medium or reproducing the recorded information, wherein the first period and the second period are smaller than a spot diameter of a guide beam irradiated on the guide layer Because
First area detecting means for detecting the first area;
Second area detecting means for detecting the second area;
An information recording / reproducing apparatus comprising: a switching area detecting unit configured to detect the switching area based on at least one of the detection results of the first area and the second area.
In at least one of the first area and the second area in the recording medium, the pits and the spaces are periodically arranged at a predetermined period in the track direction,
At least one of the first region detection unit and the second region detection unit is configured to detect the first region or the second region based on a peak interval in a predetermined period of a detection signal obtained from the first region or the second region. The information recording / reproducing apparatus according to claim 1, wherein two areas are detected.
At least one of the first region detection unit and the second region detection unit detects the first region or the second region when the peak interval coincides with the predetermined cycle continuously for a predetermined number of times. The information recording / reproducing apparatus according to claim 2, wherein:
At least one of the first region detection unit and the second region detection unit detects, as the peak interval, a peak interval on the positive polarity side and a peak interval on the negative polarity side, and the peak interval on the positive polarity side and the negative electrode 4. The information recording / reproducing apparatus according to claim 3, wherein the first area or the second area is detected when both of the sex-side peak intervals coincide with the predetermined period continuously for the predetermined number of times. .
At least one of the first region detection unit and the second region detection unit detects, as the peak interval, a peak interval on the positive polarity side and a peak interval on the negative polarity side, and the peak interval on the positive polarity side and the negative electrode 4. The information recording according to claim 3, wherein the first area or the second area is detected when any one of the sex-side peak intervals coincides with the predetermined period continuously for the predetermined number of times. Playback device.
2. The information recording according to claim 1, wherein at least one of the first area detection unit and the second area detection unit detects the first area or the second area with a tracking servo opened. Playback device.
A guide layer in which a guide track for tracking is formed, and a plurality of recording layers stacked on the guide layer;
The guide track is a single spiral track in which land tracks having a land structure and groove tracks having a groove structure are alternately arranged,
A switching region for switching the land track and the groove track is formed at a predetermined rotational phase position of the guide layer,
The switching area is
A first region in which pits and spaces are periodically arranged at a first period in the radial direction at the same rotational phase position;
A second region in which the pits and the spaces are periodically arranged in a second period different from the first period in the radial direction at the same rotational phase position;
An information recording / reproducing method for recording information on a recording medium or reproducing recorded information, wherein the first period and the second period are smaller than a spot diameter of a guide beam irradiated on the guide layer Because
A first region detecting step of detecting the first region;
A second region detecting step of detecting the second region;
A switching area detecting step of detecting the switching area based on at least one of the detection results of the first area and the second area. An information recording / reproducing method comprising: