WO2012153390A1

WO2012153390A1 - Recording medium, manufacturing device and method for manufacturing recording medium, playback device and method for playing back recording medium

Info

Publication number: WO2012153390A1
Application number: PCT/JP2011/060756
Authority: WO
Inventors: 冨田　吉美; 横川　文彦; 西脇　宏
Original assignee: パイオニア株式会社
Priority date: 2011-05-10
Filing date: 2011-05-10
Publication date: 2012-11-15

Abstract

In order to suppress an increase in the signal level of a focus servo signal or a focus summation signal in an area where barcode information is to be recorded (for example, a BCA): a recording medium (10) is provided with a playback information recording area (14) and control information recording areas (12, 13); barcode information (121) is recorded at a CAV over a plurality of recording tracks in the control information recording area; overwrite information (P2) is recorded at a CAV over a plurality of recording tracks on an unrecorded portion (1212) constituting barcode information; and the average level of the signal strength when the overwrite information is read is greater than or equal to the average level of the signal strength when a first pit portion (1211, P1) is read, and is less than the average level of the signal strength when a first unrecorded portion (1212) is read.

Description

RECORDING MEDIUM, MANUFACTURING APPARATUS AND METHOD FOR PRODUCING RECORDING MEDIUM, REPRODUCING APPARATUS AND METHOD FOR PLAYING RECORDING MEDIUM

An area called a BCA (Burst Cutting Area) is formed on an optical disc such as a DVD (Digital Versatile Disc) or a BD (Blu-ray Disc) (see Patent Documents 1 and 2 below). . On the BCA, a barcode-like pattern is recorded, which is a combination of a region where the reflection film is burned out by irradiation with a YAG laser or the like and a region where the reflection film remains after irradiation of the YAG laser or the like. ing. Such a barcode-like pattern indicates information unique to the optical disc.

JP 2005-196942 A International Publication No. 2006/109607 Pamphlet International Publication No. 2005/093729 Pamphlet

In order to record a barcode pattern on the BCA, in addition to a normal optical disk forming process (for example, a stamper forming process or an optical disk duplication process using a stamper), a process of irradiating a YAG laser is required. It will be necessary further. Therefore, manufacturing costs and the like are relatively increased. For this reason, a method of recording a barcode-like pattern formed by the presence or absence of pre-pits on the BCA instead of a barcode-like pattern formed by the presence or absence of a reflection film accompanying YAG laser irradiation is considered as an alternative. (See Patent Document 3 above.) According to this method, since the prepits can be formed by the stamper, the BCA is formed in a normal optical disk forming process (for example, a stamper forming process, an optical disk duplication process using the stamper, etc.) (that is, A barcode-like pattern can be recorded).

However, when a barcode-like pattern formed by the presence or absence of pre-pits is recorded on the BCA, an unrecorded area where no pre-pits are formed is included in the barcode-like pattern. For this reason, the technical problem shown below may arise.

Specifically, on a read-only (ROM) optical disc, recording in which prepits in the barcode pattern are formed in an unrecorded area of the barcode pattern in which the prepits are not formed. The reflectance is relatively high compared to the finished region. For this reason, the signal level of the focus error signal and the focus sum signal generated based on the reflected light in the unrecorded area where the prepits are not formed compared to the recorded area where the prepits are formed. Becomes relatively large. At this time, if the signal level of the focus error signal in the unrecorded area where no pre-pit is formed becomes relatively high, the focus servo gain calculated according to the focus error signal is also relative. Will become bigger. As a result, a technical problem that the phase margin in the focus servo control becomes relatively small may occur.

Also, the focus servo gain is preferably within the range of a predetermined margin defined in advance for the entire optical disc in accordance with the standard. On the other hand, when the signal level of the focus sum signal in the unrecorded area where no pre-pits are formed becomes large, pre-pits are formed in order to keep the focus servo gain within a predetermined margin range. In spite of the fact that the signal level of the focus sum signal other than the unrecorded area is not increased, it is necessary to reduce the gain of the preamplifier constituting the reading system. If the gain of the preamplifier is lowered in accordance with the signal level of the focus sum signal in the unrecorded area where only a part of the pre-pits are not formed in this way, the residual error in the focus servo control will be seen from the whole optical disk. As a result, there may be a technical problem that the reproduction quality deteriorates.

Examples of problems to be solved by the present invention include the above. The present invention is a recording medium capable of suppressing an increase in the signal level of a focus error signal or a focus sum signal caused by an area (for example, BCA) in which barcode information (that is, a barcode-like pattern) is recorded. It is an object of the present invention to provide a manufacturing apparatus and method for manufacturing such a recording medium, and a reproducing apparatus and method for reproducing such a recording medium.

In order to solve the above problems, a recording medium includes a reproduction information recording area in which reproduction information is recorded, and a control information recording area in which control information for controlling reproduction of the reproduction information is recorded, In at least a part of the information recording area, bar code information in which a first pit portion in which a plurality of first recording pits are formed and a first unrecorded portion in which the first recording pit is not formed is combined. In addition, CAV (Constant Angular Velocity) recording is performed across a plurality of recording tracks, and a part of the first unrecorded portion constituting the barcode information is overwritten on the first unrecorded portion. When overwriting information is CAV-recorded across a plurality of recording tracks, the overwriting information has an average level of signal intensity when the overwriting information is read, when the first pit portion is read It said first unrecorded portion where the average level over the result and overwriting information of the signal strength is not overwritten is recorded to an average level less than the signal strength when played.

In order to solve the above-mentioned problem, the manufacturing apparatus is a manufacturing apparatus for manufacturing a recording medium including a reproduction information recording area and a control information recording area, and the first recording means records the reproduction information in the reproduction information recording area. And second recording means for recording control information in the control information recording area, wherein the second recording means has a plurality of first recording pits formed as at least part of the control information. Barcode information in which a pit portion and a first unrecorded portion in which the first recording pit is not formed is combined is recorded over a plurality of recording tracks by CAV (Constant-Angular-Velocity), and the second recording means Further, overwriting information overwritten on a part of the first unrecorded part over the first unrecorded part is CAV-recorded across a plurality of recording tracks on a part of the first unrecorded part constituting the barcode information, First In the recording means, the average level of the signal intensity when the overwriting information is read is equal to or higher than the average level of the signal intensity when the first pit portion is read, and the overwriting information is not overwritten. (1) The overwriting information is recorded so that the reproduction signal intensity is less than the average level when the unrecorded portion is read.

In order to solve the above-mentioned problem, a manufacturing method is a manufacturing method for manufacturing a recording medium including a reproduction information recording area and a control information recording area, and a first recording step of recording reproduction information in the reproduction information recording area And a second recording step for recording control information in the control information recording area, wherein the second recording step is a first in which a plurality of first recording pits are formed as at least part of the control information. Barcode information in which a pit portion and a first unrecorded portion in which the first recording pit is not formed is combined is recorded over a plurality of recording tracks by CAV (Constant-Angular-Velocity), and the second recording step includes Further, overwriting information overwritten on a part of the first unrecorded part over the first unrecorded part is CAV-recorded across a plurality of recording tracks on a part of the first unrecorded part constituting the barcode information, First In the recording step, the average level of the signal intensity when the overwriting information is read is equal to or higher than the average level of the signal intensity when the first pit portion is read, and the overwriting information is not overwritten. (1) The overwriting information is recorded so that the reproduction signal intensity is less than the average level when the unrecorded portion is read.

In order to solve the above-mentioned problem, a playback apparatus is a playback apparatus for playing back the above-described recording medium, and includes a first reading unit that reads a playback signal indicating the playback information from the playback information recording area, and the control information recording From the area, as the control information, a second reading means for reading a control signal indicating the barcode information, and a high frequency signal component corresponding to a predetermined cutoff frequency among the control signals read by the second reading means. A low-pass filter that shuts off; and a reproducing unit that reproduces the barcode information based on the control signal that has passed through the low-pass filter.

In order to solve the above-described problem, a reproduction method is a reproduction method for reproducing the above-described recording medium, wherein a reproduction signal indicating the reproduction information is read from the reproduction information recording area, and the control information recording is performed. A second reading step for reading a control signal indicating the barcode information as the control information from a region, and a high frequency signal component corresponding to a predetermined cutoff frequency among the control signals read by the second reading means. A low-pass filtering step of blocking, and a reproduction step of reproducing the barcode information based on the control signal that has passed through the low-pass filtering step.

It is a schematic plan view which shows the structure of the optical disk of a present Example. It is the top view and data structure figure which show the data structure of prewrite BCA with which the optical disk of a present Example is provided. It is a top view which shows the data structure of the prewrite BCA with which the optical disk of a present Example is provided in detail. The signal level of the reflected light from the optical disc, the signal level of the read signal generated by detecting the reflected light, and the reflection when the barcode information composed of the unrecorded portion where the recording pit is formed are read. From the optical disc when the signal level of the focus error signal (or the focus sum signal) generated by detecting the light and the barcode information composed of the unrecorded portion 1212 where the recording pit is not formed are read. The signal level of the reflected light, the signal level of the read signal generated by detecting the reflected light, and the signal level of the focus error signal (or the focus sum signal) generated by detecting the reflected light are shown. It is a top view and a graph. It is a block diagram which shows the focus servo system circuit which performs focus servo control. It is a graph which shows the frequency characteristic of each of the phase of the focus servo gain G (f) implement | achieved by a focus servo system circuit, and the said focus servo gain G (f). It is a graph which shows the tolerance | permissible_range of the focus servo gain G (f) in a focus servo system circuit. It is a block diagram which shows the structure of the manufacturing apparatus which manufactures the optical disk of a present Example (more specifically, the recording original disc used when many optical disks of a present Example are replicated). It is a flowchart which shows the flow of operation | movement of the manufacturing apparatus of a present Example. It is sectional drawing which shows the structure of the stamper apparatus which duplicates many optical disks using the stamper produced from the recording original disc manufactured by the manufacturing apparatus of a present Example. It is a block diagram which shows the structure of the reproducing | regenerating apparatus which reproduces | regenerates the optical disk of a present Example. It is a flowchart which shows the flow of operation | movement of the reproducing | regenerating apparatus of a present Example.

Hereinafter, embodiments of a recording medium, a manufacturing apparatus and method for manufacturing the recording medium, and a reproducing apparatus and method for reproducing the recording medium will be described in order.

(Embodiment of recording medium)
The recording medium of the present embodiment includes a reproduction information recording area in which reproduction information is recorded, and a control information recording area in which control information for controlling reproduction of the reproduction information is recorded. At least in part, barcode information in which a first pit portion in which a plurality of first recording pits are formed and a first unrecorded portion in which the first recording pits are not formed is combined into a plurality of recordings. CAV (Constant Angular Velocity) is recorded across the track,
Overwriting information to be overwritten on the first unrecorded part is CAV recorded across a plurality of recording tracks on a part of the first unrecorded part constituting the barcode information,
In the overwriting information, the average level of the signal intensity when the overwriting information is read is equal to or higher than the average level of the signal intensity when the first pit portion is read, and the overwriting information is not overwritten. The first unrecorded portion is recorded so as to be less than the average level of the signal intensity when the first unrecorded portion is reproduced.

According to the recording medium of the present embodiment, reproduction information (for example, video information and audio information) is recorded in a reproduction information recording area (for example, a data area to be described later). Further, control information for controlling reproduction of reproduction information is recorded in a control information recording area (for example, a prewrite BCA (Burst Cutting Area) or a lead-in area described later).

Bar code information is CAV-recorded (that is, recorded with a constant angular velocity) across a plurality of recording tracks in at least a part of the control information recording area. The barcode information does not necessarily have to be recorded on the entire circumference of the recording medium, and may be recorded in an arc shape that falls within a predetermined central angle range. When the barcode information is recorded in an arc shape, the boundary portion of the barcode information may be maintained in an unrecorded state, for example. For example, (i) the bar code information is recorded on the first recording track, an unrecorded area is secured following the bar code information, and (ii) the second recording following the first recording track. In the recording track, the bar code information is recorded in the area at the same angle (or central angle) as the bar code information of the first recording track, following the unrecorded state area of the first recording track. After the barcode information, an unrecorded area is secured, and thereafter the barcode information is repeatedly recorded in a similar manner across a plurality of recording tracks. Therefore, when looking at the recording surface of the recording medium, barcode information is recorded in an area on an arc that spans a plurality of recording tracks and falls within a predetermined angle (predetermined central angle), and is recorded in an area between both ends of the arc. A corresponding area on the arc is secured as an unrecorded area (a gap area described later).

Bar code information is information in which the first pit portion and the first unrecorded portion are combined. A plurality of first recording pits are formed in the first pit portion. Further, a plurality of first recording spaces corresponding to the plurality of first recording pits may be formed in the first pit portion. On the other hand, in the first unrecorded portion, the first recording pit (further, the first recording space corresponding to the first recording pit) is not formed. For this reason, a barcode-like pattern is realized by the combination of the first pit portion and the first unrecorded portion, and the barcode information pattern becomes the barcode information as a result.

Particularly in this embodiment, predetermined overwriting information is recorded in the first unrecorded portion. The overwriting information is recorded in the first unrecorded part to such an extent that the reading system that reads the barcode information can recognize the first unrecorded part as an unrecorded area. Is preferred. In other words, the overwriting information cannot be detected separately from the information other than the overwriting information in the reading system that reads the barcode information (for example, the signal component is cut by a low-pass filter described later). It is preferable to record discretely dispersed (or subdivided) in the recording unit. For example, the overwriting information may be information composed of second recording pits appearing at a frequency, interval, or period lower than or very low than the appearance frequency of the first recording pits in the first pit portion.

Particularly in the present embodiment, the barcode information and the overwriting information are overwritten when the average level of the signal strength when the overwriting information is read is equal to or higher than the average level of the signal strength when the first pit portion is read. Recording is performed so that the first unrecorded portion in the state where information is not overwritten is less than the average level of signal intensity when reading. Therefore, the average level of the signal intensity when the first unrecorded portion in which the overwrite information is overwritten is read is the signal intensity when the first unrecorded portion in which the overwrite information is not overwritten is read. Compared to the average level of Therefore, the average level of the signal intensity when the barcode information including the first unrecorded portion in the overwritten information state is read is the bar level including the first unrecorded portion in the overwritten information state. Compared to the average level of signal strength when code information is read, it is relatively small.

For this reason, in the present embodiment, the overwriting information is not overwritten (that is, the first unrecorded portion is literally maintained in a completely unrecorded state) and is generated by reading the barcode information. The signal level of various signals (for example, a focus error signal, a focus sum signal, and the like) becomes relatively small or not at all. That is, in the present embodiment, an increase in the signal level of the focus error signal, the focus sum signal, and the like generated by reading the barcode information can be suppressed as compared with the case where the overwrite information is not overwritten.

For this reason, in this embodiment, compared with the case where the overwrite information is not overwritten, an increase in the signal level of the focus error signal generated by reading the barcode information can be suppressed. The focus servo gain calculated in accordance with is relatively little or not at all. Therefore, in the present embodiment, the phase margin in the focus servo control becomes relatively small or not as compared with the case where the overwrite information is not overwritten. That is, in the present embodiment, a phase margin in the focus servo control can be preferably ensured as compared with a case where the overwrite information is not overwritten.

In addition, in this embodiment, since the increase in the signal level of the focus sum signal generated by reading the barcode information can be suppressed as compared with the case where the overwrite information is not overwritten, the entire recording medium In order to keep the focus servo gain in the range of a predetermined margin, it is not necessary to forcibly reduce the gain of the preamplifier constituting the reading system. For this reason, in this embodiment, compared with the case where the overwrite information is not overwritten, the residual error in the focus servo control is relatively little or not at all, and as a result, the reproduction quality is lowered. Little or no. That is, in the present embodiment, it is possible to realize a preferable reproduction quality as compared with the case where the overwrite information is not overwritten.

In one aspect of the recording medium of the present embodiment, the overwriting information includes a second pit portion in which a second recording pit is formed.

According to this aspect, the overwriting information can be recorded using the second pit portion including the second recording pit. That is, a part of the first unrecorded part can be changed to a recorded state. For this reason, compared with the case where overwrite information is not overwritten, the increase in the signal level of the various signals produced | generated by reading barcode information can be suppressed. Therefore, the various effects described above can be suitably enjoyed.

It should be noted that a plurality of second recording spaces corresponding to a plurality of second recording pits may be formed in the second pit portion.

As described above, in the aspect of the recording medium in which the overwriting information includes the information constituted by the second pit portion, the length of the second pit portion along the rotation direction of the recording medium is the rotation direction of the recording medium. You may comprise so that it may be smaller than the length of the said 1st pit part along.

With this configuration, it is possible to form the second pit portion that is relatively short compared to the first pit portion (in other words, the width along the rotation direction of the recording medium is small or narrow). . For this reason, the width on the time axis of the waveform of the read signal corresponding to the second pit portion is a very narrow waveform (that is, a high frequency). Therefore, the signal (that is, the overwrite information) from the second pit portion is cut by a low-pass filter described later that the reading system that reads the barcode information has. For this reason, the first unrecorded part is recognized as an unrecorded area. On the other hand, since the width on the time axis of the waveform of the read signal corresponding to the first pit part is relatively wide, the first pit part uses a low-pass filter described later included in the reading system that reads the barcode information. The signal is never cut. For this reason, the first pit portion is recognized as a recorded region. Therefore, even if the overwriting information including the second pit portion is overwritten on the first unrecorded portion, it hardly affects the reading of the barcode information composed of the first pit portion and the first unrecorded portion or Not at all.

In addition, the cut-off frequency of the low-pass filter in the focus servo control system is generally about two digits lower than the cut-off frequency of the low-pass filter in the reading system that reads barcode information. For this reason, in the reading system for reading the barcode information, the signal (that is, the overwrite information) from the second pit portion is cut, whereas in the focus servo control system, the signal from the second pit portion (that is, the overwrite information). Therefore, it is possible to suppress an increase in signal levels such as a focus error signal and a focus sum signal generated by reading barcode information.

As described above, in the aspect of the recording medium in which the overwriting information includes information configured by the second pit portion, the ratio or density occupied by the second pit portion per unit length along the rotation direction of the recording medium is: You may comprise so that the ratio or density which the said 1st pit part per unit length along the rotation direction of the said recording medium occupies may be smaller.

With this configuration, it is possible to form the second pit portion that appears relatively less frequently than the first pit portion. As a result, it is possible to form a second pit portion that is relatively short compared to the first pit portion (in other words, the width along the rotation direction of the recording medium is small or narrow). For this reason, the width on the time axis of the waveform of the read signal corresponding to the second pit portion is a very narrow waveform (that is, a high frequency). Therefore, the signal (that is, the overwrite information) from the second pit portion is cut by a low-pass filter described later that the reading system that reads the barcode information has. For the sake of convenience, the first unrecorded part is recognized as an unrecorded area. On the other hand, since the width on the time axis of the waveform of the read signal corresponding to the first pit part is relatively wide, the first pit part uses a low-pass filter described later included in the reading system that reads the barcode information. The signal is never cut. For this reason, the first pit portion is recognized as a recorded region. Therefore, even if the overwriting information including the second pit portion is overwritten on the first unrecorded portion, it hardly affects the reading of the barcode information composed of the first pit portion and the first unrecorded portion or Not at all.

As described above, in the aspect of the recording medium in which the boundary information includes information constituted by the second pit part, the period in which the second pit part appears along the rotation direction of the recording medium is the second number that constitutes the reproduction information. The three recording pits may be configured to have a period equal to or less than a period corresponding to a combination of the longest recording pit having the maximum length along the rotation direction of the recording medium and the longest recording space corresponding to the longest recording pit. .

With this configuration, a signal (that is, overwriting information) from the second pit portion is cut by a low-pass filter (described later) included in the reading system that reads the barcode information, so the first unrecorded portion is Is recognized as an unrecorded area. On the other hand, since the width on the time axis of the waveform of the read signal corresponding to the first pit part is relatively wide, the first pit part uses a low-pass filter described later included in the reading system that reads the barcode information. Since the signal is not cut, the first pit portion is recognized as a recorded state area. Therefore, even if the overwriting information including the second pit portion is overwritten on the first unrecorded portion, it hardly affects the reading of the barcode information composed of the first pit portion and the first unrecorded portion or Not at all.

As described above, in the aspect of the recording medium in which the boundary information includes the information constituted by the second pit part, the length of the second pit part along the rotation direction of the recording medium is the first of the reproduction information. The length of the three recording pits along the rotation direction of the recording medium is not more than the maximum value, and the length of the third recording pit along the rotation direction of the recording medium is not less than the minimum value. Also good.

(Embodiment of manufacturing apparatus)
The manufacturing apparatus of the present embodiment is a manufacturing apparatus that manufactures a recording medium including a reproduction information recording area and a control information recording area, and includes a first recording unit that records reproduction information in the reproduction information recording area, and the control A second recording means for recording control information in an information recording area, wherein the second recording means includes, as at least a part of the control information, a first pit portion in which a plurality of first recording pits are formed, Barcode information combined with the first unrecorded portion where the first recording pit is not formed is recorded over a plurality of recording tracks by CAV (Constant Angular Velocity), and the second recording means further includes Overwriting information that is overwritten on a portion of the first unrecorded portion constituting the barcode information is CAV-recorded across a plurality of recording tracks, and the second recording means Said The first unrecorded portion in a state where the average level of the signal intensity when the overwriting information is read is equal to or higher than the average level of the signal strength when the first pit portion is read and the overwriting information is not overwritten. The overwriting information is recorded so that the reproduction signal intensity is less than the average level when read.

According to the manufacturing apparatus of the present embodiment, the above-described recording medium of the present embodiment (including various aspects thereof) can be preferably manufactured. The manufacturing apparatus of this embodiment may be an apparatus for manufacturing a recording medium corresponding to a so-called master stamper, or an apparatus for manufacturing a recording medium by duplicating the recording medium based on the master-stamper. It may be.

Incidentally, the manufacturing apparatus of this embodiment can also take various aspects in response to the various aspects that the above-described recording medium of this embodiment can take.

In one aspect of the manufacturing apparatus of the present embodiment, the manufacturing apparatus further includes a duplicating unit that duplicates the recording medium on which the reproduction information and the control information are recorded.

According to this aspect, the above-described recording medium of the present embodiment (including various aspects thereof) can be preferably manufactured.

(Embodiment of manufacturing method)
The manufacturing method of the present embodiment is a manufacturing method for manufacturing a recording medium including a reproduction information recording area and a control information recording area, and includes a first recording step of recording reproduction information in the reproduction information recording area, and the control A second recording step of recording control information in an information recording area, wherein the second recording step includes, as at least a part of the control information, a first pit portion in which a plurality of first recording pits are formed, and The barcode information combined with the first unrecorded portion where the first recording pit is not formed is recorded over a plurality of recording tracks by CAV (Constant Angular Velocity), and the second recording step further includes Overwriting information to be overwritten over a portion of the first unrecorded portion constituting the barcode information is CAV recorded across a plurality of recording tracks, and the second recording step Said The first unrecorded portion in a state where the average level of the signal intensity when the overwriting information is read is equal to or higher than the average level of the signal strength when the first pit portion is read and the overwriting information is not overwritten. The overwriting information is recorded so that the reproduction signal intensity is less than the average level when read.

According to the manufacturing method of the present embodiment, it is possible to suitably enjoy the same effects as the various effects that can be enjoyed by the above-described manufacturing apparatus of the present embodiment.

In addition, the manufacturing method of this embodiment can also take various aspects corresponding to the various aspects which the manufacturing apparatus of this embodiment mentioned above can take.

(Embodiment of playback device)
The playback apparatus of the present embodiment is a playback apparatus for playing back the recording medium of the present embodiment described above (including various aspects thereof), and reads the playback signal indicating the playback information from the playback information recording area. 1 reading means, a second reading means for reading a control signal indicating the bar code information as the control information from the control information recording area, and a predetermined cutoff among the control signals read by the second reading means A low-pass filter that cuts off a high-frequency signal component corresponding to the frequency; and a reproducing unit that reproduces the barcode information based on the control signal that has passed through the low-pass filter.

According to the reproducing apparatus of the present embodiment, the above-described overwriting information is cut by the filtering process by performing the filtering process by the low-pass filter on the control signal indicating the barcode information. The barcode information recorded on the recording medium (including various aspects thereof) can be suitably reproduced.

Incidentally, in response to the various aspects that the recording medium of the present embodiment can take, the playback apparatus of the present embodiment can also take various aspects.

In one aspect of the reproducing apparatus of the present embodiment, the low-pass filter is a second-order Bessel low-pass filter in which the cutoff frequency is 500 kHz.

According to this aspect, the barcode information and the boundary information can be suitably reproduced using the reproduction system for reproducing the reproduction information.

(Embodiment of reproduction method)
The playback apparatus according to the present embodiment is a playback method for playing back the recording medium described in the above-described recording medium of the present embodiment (including various aspects thereof), wherein the playback information is recorded from the playback information recording area. A first reading step for reading the reproduced signal, a second reading step for reading the control signal indicating the barcode information as the control information from the control information recording area, and the control signal read by the second reading means. A low-pass filtering step that blocks a high-frequency signal component corresponding to a predetermined cutoff frequency, and a reproduction step that reproduces the barcode information based on the control signal that has passed through the low-pass filtering step.

According to the playback method of the present embodiment, it is possible to suitably enjoy the same effects as the various effects that can be enjoyed by the playback apparatus of the present embodiment described above.

Incidentally, in response to the various aspects that can be taken by the reproduction apparatus of the present embodiment described above, the reproduction method of the present embodiment can also take various aspects.

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

As described above, in the recording medium of the present embodiment, the average level of the signal intensity when the overwriting information is read is equal to or higher than the average level of the signal intensity when the first pit portion is read, and the overwriting information is The first unrecorded portion that has not been overwritten is less than the average level of signal strength when read. According to the manufacturing apparatus of the present embodiment, the first recording unit and the second recording unit are provided. According to the manufacturing method of the present embodiment, the first recording step and the second recording step are provided. According to the reproducing apparatus of this embodiment, the first reading unit, the second reading unit, the low-pass filter, and the reproducing unit are provided. According to the reproducing apparatus of the present embodiment, the first reading step, the second reading step, the filtering step, and the reproducing step are provided. Accordingly, it is possible to suppress an increase in the signal level of the focus error signal or the focus sum signal caused by the area (for example, BCA) where the barcode information is recorded.

Hereinafter, embodiments of a recording medium, a manufacturing apparatus and method for manufacturing the recording medium, and a reproducing apparatus and method for reproducing the recording medium will be described with reference to the drawings.

(1) Optical Disc With reference to FIG. 1, the basic structure of an optical disc 10 as an example of a recording medium will be described. FIG. 1 is a schematic plan view showing the structure of the optical disk 10 of this embodiment.

As shown in FIG. 1, an optical disk 10 has a lead-in area 13 and a data area 14 on a recording surface on a disk main body having a diameter of about 12 cm like a DVD or BD. And a lead-out area 15. In each area, for example, a groove track and a land track may be alternately provided spirally or concentrically around the center hole 11, or the groove track may be wobbled. Prepits may be formed on one or both of the tracks. The present invention is not particularly limited to an optical disc having such three areas. For example, the lead-in area 13 and the lead-out area 14 may not exist. Further, the lead-in area 13 and the lead-out 15 may be further subdivided.

In this embodiment, the optical disk 10 is preferably a read-only optical disk such as a DVD-ROM or a BD-ROM. Accordingly, in the lead-in area 13, the data area 14, and the lead-out area 15, predetermined information (for example, audio information, video information, control information, management information, etc.) is stored in advance at the time of shipment of the optical disc 10. It is preferably recorded by embossed pits. However, the optical disk 10 may be a recordable optical disk such as a DVD-R, DVD-RW, BD-R, or BD-RE. In this case, predetermined information may not be recorded in advance in the lead-in area 13, the data area 14, and the lead-out area 15 when the optical disc 10 is shipped.

The optical disc 10 further includes a prewrite BCA (Burst Cutting１２Area) 12 on the inner peripheral side of the lead-in area 13. For example, barcode information 121 indicating information unique to the optical disc 10 is recorded in the prewrite BCA 12. The bar code information 121 is CAV recorded across a plurality of recording tracks (for example, a groove track or a land track). That is, the barcode information 121 is recorded in an arc shape having a predetermined center angle and straddling a plurality of recording tracks.

A gap area 122, which is an unrecorded area, is secured at the end of the barcode information 121 (in other words, the boundary between the start and end of the barcode information 121). Accordingly, the barcode information 121 is recorded in an arc shape having a predetermined center angle and straddling a plurality of recording tracks, and the unrecorded gap area 122 fills the arc in which the barcode information 121 is recorded. In order to form a circle, a circular arc extending over a plurality of recording tracks is secured.

Subsequently, the prewrite BCA 12 provided in the optical disc 10 of this embodiment will be described with reference to FIGS. FIG. 2 is a plan view and a data structure diagram showing a data structure of the prewrite BCA 12 provided in the optical disc 10 of the present embodiment. FIG. 3 is a plan view showing in more detail the data structure of the prewrite BCA 12 provided in the optical disc 10 of the present embodiment.

As shown in FIG. 2A, the barcode information 121 is information in which a pit portion 1211 in which a plurality of recording pits P1 are formed and an unrecorded portion 1212 in which no recording pits P1 are formed are combined. For example, the barcode information 121 in which the pit portion 1211 and the unrecorded portion 1212 are combined in this order may indicate bit information “1”. On the other hand, for example, the barcode information 121 in which the unrecorded portion 1212 and the unrecorded portion 1212 are combined in this order may indicate bit information of “0”. Depending on the combination of the pit portion 1211 and the unrecorded portion 1212, information unique to the optical disc 10 is recorded as bar code information.

The recording pit P1 is preferably an embossed pit formed by, for example, a stamper. In the conventional BCA, barcode information is recorded by burning out the reflective film by irradiation with a YAG laser or the like. On the other hand, in the present embodiment, by forming the recording pit P1, a state substantially similar to the state in which the reflective film is burned out is realized. Specifically, the pit portion 1211 where the recording pit P1 is formed corresponds to a region where the conventional reflective film is burned out, and the unrecorded portion 1211 where the recording pit P1 is not formed is burned out in the conventional reflective film. Corresponds to the uncut area. In the present embodiment, the conventional BCA in which the barcode information is recorded by burning the reflection film and the BCA 12 in the present embodiment in which the barcode information 121 is recorded by forming the recording pit P1 are distinguished. Therefore, the expression “pre-write BCA12” is adopted.

The recording pit P1 has a pit length (in other words, a run length) that is less than or equal to the maximum pit length of the recording pits formed in the lead-in area 13, the data area 14, and the lead-out area 15. It is preferable that it becomes more than a value. For example, if the optical disc 10 is a BD-ROM, the pit length of the recording pit P1 is preferably 2T or more and 9T or less.

In this embodiment, a recording pit P2 is further recorded in a part of the unrecorded portion 1212 constituting the barcode information 121. The recorded pits P2 are preferably not recorded so as to be distributed over the entire unrecorded portion 1212. That is, the recorded pits P1 are recorded so as to be distributed over the entire pit portion 1211, while the recorded pits P2 are recorded so as to be distributed discretely or locally only in a part of the unrecorded portion 1212. Is done. In other words, it is preferable that the recording pits P2 are formed in the unrecorded portion 1212 with a relatively narrow stripe pattern. In other words, the recording pits P2 are formed in the unrecorded portion 1212 so as not to prevent the unrecorded portion 1212 from being recognized as being unrecorded by a reading system that reads bar code information 121 described later. Is preferred.

More specifically, as shown in FIG. 3, for example, the width (or length) w2 along the rotation direction of the optical disc 10 in the area where the recording pit P2 is formed is the area where the recording pit P1 is formed. That is, it is preferable that the width (or length) w1 of the pit portion 1211 along the rotation direction of the optical disk 10 is smaller. With this configuration, the recorded pits P2 are recorded so as to be distributed discretely or locally only in a part of the unrecorded pit portion 1211.

Alternatively, as shown in FIG. 3, for example, the density of the recorded pits P2 per unit length (or per unit area) in the unrecorded portion 1212 is equal to the unit length per unit length (or unit area) in the pit portion 1211. It is preferable that the density is smaller than the density of the recording pits P1. With this configuration, the recorded pits P2 are recorded so as to be distributed discretely or locally only in a part of the unrecorded pit portion 1211.

In addition, the period in which the recording pits P2 appear (that is, the interval between one group of recording pits P2 and the next group of recording pits P2) t is formed in the lead-in area 13, the data area 14, and the lead-out area 15. It is preferable that the period is equal to or shorter than the cycle corresponding to the sum of the longest recording mark of the longest recording mark and the longest recording space corresponding to the longest recording mark. For example, if the optical disc 10 is a BD-ROM, the period t at which the recording pit P2 appears is preferably equal to or less than the period corresponding to the sum of 9T mark + 9T space (ie, 18T).

Further, the recording pit P2 has a pit length (in other words, a run length) that is less than or equal to the maximum pit length of the recording pits formed in the lead-in area 13, the data area 14, and the lead-out area 15. It is preferable that it becomes more than a value. For example, if the optical disc 10 is a BD-ROM, the pit length of the recording pit P2 is preferably 2T or more and 9T or less.

As shown in FIG. 2B, neither the recording pit P1 nor the recording pit P2 is formed in the gap region 122. That is, the gap region 122 is a region where the entire surface is in an unrecorded state (in other words, a mirror state).

As shown in FIG. 2 (c), the barcode information 121 has four data units. A gap area 122 having a size of about 8.5 bytes is secured at the end of the four data units. Each data unit has four data frames and four parity frames. Each data frame has 1 synchronization byte and 4 data bytes. Each parity frame has 1 synchronization byte and 4 parity bytes.

Subsequently, with reference to FIG. 4, regarding the technical effect realized by forming the recorded pit P2 in the unrecorded portion 1212, the recorded pit P2 is not formed in the unrecorded portion 1212 (that is, unrecorded). This will be described in comparison with an optical disk of a comparative example (the entire surface of the section 1212 is maintained in an unrecorded state). FIG. 4 is generated by detecting the signal level of the reflected light from the optical disc 10 when the barcode information 121 composed of the unrecorded portion 1212 in which the recording pit P2 is formed is read, and the reflected light. The signal level of the read signal (that is, the HF signal), the signal level of the focus error signal (or the focus sum signal) generated by detecting the reflected light, and the unrecorded portion 1212 where the recording pit P2 is not formed. Is generated by detecting the signal level of the reflected light from the optical disc 10, the signal level of the read signal generated by detecting the reflected light, and the reflected light It is the top view and graph which show the signal level of the focus error signal (or focus sum total signal) performed.

As shown in FIG. 4A, when reading the barcode information 121 composed of the unrecorded portion 1212 in which the recording pits P2 are formed, the reproduction apparatus 50 described later uses a laser beam for the barcode information 121. LB is irradiated. As a result, the reflected light having the signal level shown in the upper part of FIG.

Focusing on the waveform of the read signal (that is, the HF signal) generated by receiving such reflected light, as shown in the middle part of FIG. 4A, the signal level at the position corresponding to the pit portion 1211 ( Specifically, the average value of the signal levels (hereinafter the same) is relatively low, and the signal level at the position corresponding to the unrecorded portion 1212 is relatively high. In the pit portion 1211, as shown in FIG. 2A, a long recording pit P1 extending over the entire pit portion 1211 is not formed. Alternatively, as shown in FIG. 2A, the recording pit P1 is not recorded in the pit portion 1211 without a gap. Actually, as shown in FIG. 2A, recording pits P1 and recording spaces corresponding to the recording pits P1 are alternately formed in the pit portion 1211. For this reason, as shown in the upper part of FIG. 4A, the signal level of the reflected light when the pit portion 1211 is read varies finely in accordance with the alternate formation of the recording pits P1 and the recording spaces. However, such fine fluctuations in the signal level are cut by a low-pass filter (specifically, the filter 541 in FIG. 11) provided in the reproduction system circuit that generates the read signal. In addition, with respect to fluctuations in the signal level of the reflected light corresponding to the recorded pits P2 discretely or locally formed in the unrecorded portion 1212, a low-pass filter (specifically, provided in a reproduction system circuit that generates a read signal) Is cut by the filter 541) of FIG. On the other hand, the fluctuation of the signal level of the pit part 1211 itself (that is, the fall of the signal level corresponding to the start end of the pit part 1211 and the rise of the signal level corresponding to the end of the pit part 1211) reproduces the read signal. The filter is not cut by the low-pass filter (specifically, the filter 541 in FIG. 11) included in the system circuit.

Note that the signal level of the read signal when reading the unrecorded portion 1212 where the recording pit P2 is formed is equal to or higher than the signal level of the read signal when reading the pit portion 1211 and the recorded pit P2 is not formed. It becomes less than the signal level of the read signal when the recording unit 1212 is read. In other words, in this embodiment, the signal level of the read signal when the unrecorded portion 1212 where the recording pit P2 is formed is equal to or higher than the signal level of the read signal when the pit portion 1211 is read and recorded. The recorded pits P2 are discretely or locally formed in the unrecorded part 1212 so that a state in which the signal level of the read signal when the unrecorded part 1212 in which the pit P2 is not formed is read can be realized. Is formed.

On the other hand, attention is focused on the waveform of the focus error signal “Ferr” or the focus sum signal “Fsum” (hereinafter collectively referred to as “focus system signal”) generated by receiving such reflected light. The cutoff frequency of the low-pass filter provided in the focus servo system circuit that generates the focus system signal is compared with the cutoff frequency of the low-pass filter (specifically, the filter 541 in FIG. 11) provided in the reproduction system circuit that generates the read signal. And it is about 2 digits lower. For this reason, when the focus system signal is generated from the reflected light shown in the upper part of FIG. 4A, the signal level in the pit portion 1211 varies finely and in the unrecorded portion 1212 discretely or locally. Not only the fluctuation in the signal level of the reflected light corresponding to the formed recording pit P2, but also the fluctuation in the signal level of the pit portion 1211 itself is cut by a low-pass filter provided in the focus servo system circuit that generates the focus system signal. . Therefore, the focus signal is a signal having a signal level of R1, as shown in the lower part of FIG.

The signal level of the focus system signal generated from the unrecorded part 1212 in which the recording pit P2 is formed is equal to or higher than the signal level of the focus system signal generated only from the pit part 1211, and the recording pit P2 is not formed. It becomes less than the signal level of the focus system signal generated only from the unrecorded portion 1212. Conversely, in this embodiment, the signal level of the focus system signal generated from the unrecorded part 1212 in which the recording pit P2 is formed is equal to or higher than the signal level of the focus system signal generated only from the pit part 1211. In order to realize a state where the signal level is lower than the signal level of the focus system signal generated only from the unrecorded portion 1212 in which the recorded pit P2 is not formed, the recorded pit P2 is discretely or not included in the unrecorded portion 1212. It is formed locally.

On the other hand, as shown in FIG. 4B, when reading the barcode information 121 composed of the unrecorded portion 1212 in which the recording pit P <b> 2 is not formed, the reproduction device 50 described later includes the barcode information 121. On the other hand, the laser beam LB is irradiated. As a result, the reflected light having the signal level shown in the upper part of FIG.

Focusing on the waveform of the read signal (that is, the HF signal) generated by receiving such reflected light, the signal level at the position corresponding to the pit portion 1211 is as shown in the middle of FIG. The signal level at the position corresponding to the unrecorded portion 1212 is relatively low and is relatively high as in the optical disc 10 of the present embodiment. However, since the recording pit P2 is not formed in the unrecorded portion 1212, the signal level at the position corresponding to the unrecorded portion 1212 is higher than the signal level in the optical disc 10 of this embodiment.

On the other hand, attention is focused on the waveform of the focus system signal generated by receiving such reflected light. Since the recording pit P2 is not formed in the unrecorded portion 1212, the signal level at the position corresponding to the unrecorded portion 1212 is higher than the signal level in the optical disc 10 of this embodiment. Therefore, as shown in the lower part of FIG. 4B, the focus system signal is a signal whose signal level is R2 (where R2> R1). That is, the signal level of the focus signal generated from the barcode information 121 including the unrecorded portion 1212 in which the recording pit P2 is not formed is configured from the unrecorded portion 1212 in which the recording pit P2 is formed. It becomes higher than the signal level of the focus system signal generated from the barcode information 121. In other words, according to the optical disk 10 of the present embodiment, the signal level of the focus signal generated from the barcode information 121 is higher than that of the optical disk of the comparative example in which the recording pit P2 is not formed in the unrecorded portion 1212. The increase can be suppressed. That is, according to the optical disk 10 of the present embodiment, the signal level of the focus system signal generated from the barcode information 121 is lower than that of the comparative optical disk in which the recording pits P2 are not formed in the unrecorded portion 1212. can do. For this reason, according to the optical disk 10 of the present embodiment, the following technical effects related to the focus servo control can be suitably enjoyed.

Hereinafter, with reference to FIGS. 5 to 7, a technical effect related to the focus servo control that can be enjoyed by the optical disc 10 of the present embodiment in which the recording pit P2 is formed in the unrecorded portion 1212 will be described. FIG. 5 is a block diagram showing a focus servo system circuit that executes focus servo control. FIG. 6 is a graph showing the frequency characteristics of the focus servo gain G (f) realized by the focus servo system circuit and the phase of the focus servo gain G (f). FIG. 7 is a graph showing an allowable range of the focus servo gain G (f) in the focus servo system circuit.

As shown in FIG. 5A, the focus servo system circuit for executing the focus servo control includes an optical PU (Pick Up) 21, a preamplifier 22, a phase compensation circuit 23, a focus drive circuit 24, and a focus. And an actuator 25. Note that, as described above, the focus servo system circuit may include a low-pass filter after the optical PU 21. Further, as described above, the cut-off frequency of the low-pass filter is approximately compared with the cut-off frequency of the low-pass filter (specifically, the filter 541 in FIG. 11) provided in the reproduction system circuit that generates the read signal. It is preferably as low as 2 digits.

As shown in FIG. 5B, the light PU 21 includes a four-divided photodetector that receives the reflected light from the optical disk 10. The optical PU 21 outputs the sum (specifically, Ia + Ib + Ic + Id) of the read signals detected by the four divided detectors included in the four-divided photodetector as a focus total signal Fsum. Further, the optical PU 21 outputs the diagonal difference (specifically, (Ia + Ic) − (Ib + Id)) of the read signals detected by the four divided detector units included in the four-divided photodetector as a focus error signal Ferror.

The focus error signal “Ferr” output from the optical PU 21 is subjected to signal level gain adjustment by the preamplifier 22 so as to have an appropriate signal level for the optical disc 10. The gain adjustment by the preamplifier 22 is executed so that the signal level of the focus sum signal Fsum based on the signal read in the lead-in area 13 of the optical disc 10 becomes a predetermined set value according to the characteristics of the playback device 50 described later. Is done. The phase of the focus error signal Ferrer whose gain has been adjusted by the preamplifier 22 is compensated by the phase compensation circuit 23. The focus error signal Ferror whose phase is compensated by the phase compensation circuit 23 is handled as the focus servo gain G (f) by adjusting the gain by the focus drive circuit 24. As a result, the focus drive circuit 24 drives the focus actuator 25 based on the focus servo servo gain G (f). As a result, focus servo control is performed by driving the objective lens and the like by the focus actuator 25.

As described above, the focus servo gain G (f) used for actually performing the focus servo control is the focus error signal “Ferr” × the gain adjustment by the preamplifier 22 × the phase compensation by the phase compensation circuit 23 (however, there is frequency dependency). X Gain adjustment by the focus drive circuit 24 x The characteristic of the optical PU 21 (however, there is frequency dependence). Here, focusing on one reproducing device 50, the phase compensation by the phase compensation circuit 23, the gain adjustment by the focus drive circuit 24, and the characteristics of the optical PU 21 are substantially fixed values. The gain adjustment by the preamplifier 22 is set to an appropriate value in the lead-in area 13 as described above. Therefore, the focus servo gain G (f) substantially depends on the signal level of the focus error signal “Ferr”.

Here, when the recording pit P2 is not formed in the unrecorded portion 1212 of the prewrite BCA 12, as described with reference to FIG. 4B, the signal level of the focus error signal Ferror increases relatively. End up. As a result, as the signal level of the focus error signal “Ferr” increases, the focus servo gain G (f) also increases as shown in the upper part of FIG. At this time, as shown in the lower part of FIG. 6A, the phase margin (specifically, −180 °) of the focus servo gain G (f) corresponding to the frequency at which the focus servo gain G (f) becomes 0 dB. The degree of deviation from the phase) becomes small. Therefore, the stability of focus servo control may be impaired.

As described above, the optical PU 21 outputs the focus sum signal Fsum and the focus error signal Error. Since the signal levels of the four divided detector portions Ia to Id change the same with respect to the fluctuation of the reflected light level from the optical disc 10, the signal levels of the focus sum signal Fsum and the focus error signal Ferrer also change the same. . Therefore, suppressing the increase in the signal level of the focus sum signal Fsum instead of the signal level of the focus error signal Error suppresses the signal level of the focus error signal Error.

However, according to the optical disk 10 of the present embodiment, since the recording pit P2 is formed in the unrecorded portion 1212 of the prewrite BCA 12, as described with reference to FIG. 4A, the signal of the focus error signal Ferror An increase in level can be suppressed. Therefore, as shown in the upper part of FIG. 6B, an increase in the focus servo gain G (f) can also be suppressed. As a result, as shown in the lower part of FIG. 6B, it is possible to suitably suppress a decrease in the phase margin of the focus servo gain G (f). Therefore, according to the optical disk 10 of the present embodiment, the stability of the focus servo control can be suitably ensured.

Further, as described above, the gain adjustment by the preamplifier 22 which is an element for determining the focus servo gain G (f) is such that the signal level of the focus sum signal Fsum based on the signal read in the lead-in area 13 of the optical disc 10 is described later. It is executed so as to have a predetermined set value based on the characteristics of the playback device 50 to be played. In general, the gain margin of the focus servo gain G (f) is often set to about 6 dB as shown in FIG. 6 (of course, it may be set to any value other than 6 dB). Accordingly, the gain adjustment by the preamplifier 22 is performed so that the range of fluctuation of the focus sum signal Fsum in the entire optical disc 10 is within the range of the gain margin.

Here, in the optical disc of the comparative example in which the recording pit P2 is not formed in the unrecorded portion 1212 of the prewrite BCA 12, as shown in FIG. 7, the range of fluctuation of the focus sum signal Fsum within the data area is the range of the gain margin. Suppose that it is within. On the other hand, on the optical disk of the comparative example, BCA is formed in addition to the data area. In the BCA of the comparative example, the barcode information formed by the YAG laser is recorded as described above, and the boundary between the barcode information is maintained in an unrecorded state. Further, the area where the reflection film is not burned out by the YAG laser is left as an unrecorded portion where the entire surface is in an unrecorded state. For this reason, the signal level of the focus sum signal Fsum in the BCA may be higher than the signal level of the focus sum signal Fsum in the data area. As a result, as shown on the right side of FIG. 7, even if the range of fluctuation of the focus sum signal Fsum within the data area is within the range of the gain margin, the focus sum signal Fsum for the entire optical disk including the BCA is included. The fluctuation range may not be within the gain margin range. Therefore, in this case, it is necessary to adjust the gain by the preamplifier 22 in accordance with the focus sum signal Fsum in the BCA (that is, to reduce the gain of the preamplifier 22), but there are many residual components in the focus servo control. As a result, the reproduction quality may be deteriorated.

However, according to the optical disk 10 of the present embodiment, since the recording pit P2 is formed in the unrecorded portion 1212 of the prewrite BCA 12, an increase in the signal level of the focus sum signal Fsum in the prewrite BCA 12 can be suppressed. That is, it is possible to suppress an increase in “average level of sum signal of BCA unrecorded portion”, “average level of sum signal of BCA barcode information” and “total signal fluctuation in BCA” shown in FIG. it can. As a result, it is possible to reduce the possibility that the range of fluctuation of the focus sum signal Fsum in the entire optical disc 10 including the prewrite BCA 12 will not fall within the gain margin range. Therefore, according to the present embodiment, the gain of the preamplifier 22 does not have to be reduced more than necessary in accordance with the focus sum signal Fsum in the prewrite BCA 12, so that the residual component in the focus servo control does not increase, and as a result Deterioration of reproduction quality can be prevented.

As described above, according to the optical disc 10 of the present embodiment, the focus error signal Ferror of the prewrite BCA 12 is compared with the optical disc of the comparative example in which the recording pits P2 are not formed in the unrecorded portion 1212 of the prewrite BCA 12. The increase can be suppressed. Therefore, as described above, the focus servo control can be suitably performed, and as a result, a suitable reproduction operation can be realized.

(2) Manufacturing Device Next, a manufacturing device for manufacturing the optical disc 10 of this embodiment will be described with reference to FIGS. FIG. 8 is a block diagram showing a configuration of a manufacturing apparatus 30 that manufactures the optical disc 10 of the present embodiment (more specifically, a recording master 100 that is used when replicating a large number of the optical disc 10 of the present embodiment). It is. FIG. 9 is a flowchart showing the operation flow of the manufacturing apparatus 30 of the present embodiment. FIG. 10 is a cross-sectional view illustrating a configuration of a stamper device 40 that replicates a large number of optical disks 10 using a stamper 200 created from the recording master 100 manufactured by the manufacturing apparatus 30 of the present embodiment.

As shown in FIG. 8, the manufacturing apparatus 30 includes an LD (Laser Diode) 31, an LD drive circuit 32, a signal switching unit 33, a main data generation unit 34, a recording data source 35, and a BCA signal. A generation unit 36, a spindle motor 371, a spindle controller 372, a system controller 38, and a master clock generator 39 are provided.

The manufacturing apparatus 30 having such a configuration operates according to the flowchart shown in FIG. Specifically, as a premise of the operation shown in the flowchart of FIG. 9, first, the master clock generator 39 generates a master clock signal, and the master clock signal is generated as the spindle controller 372, the main data signal generator 34, and the BCA signal generation. To the unit 36. The spindle controller 372 is supplied with a master clock signal and a frequency signal FG indicating a rotation frequency from the spindle motor 371. The spindle controller 372 controls the rotation of the spindle motor 371 (ie, spindle servo control) so that the frequency signal FG is synchronized with the master clock signal.

In parallel with such spindle servo control, the main data signal generation unit 34 synchronizes with the master clock signal (or the recording clock signal obtained by dividing the master clock signal) (that is, information to be recorded (that is, Then, modulation according to video information, audio information, control information, management information, etc. supplied from the recording data source 35 is performed to generate a main data signal (step S30). Thereafter, the signal switching unit 33 controls the path so that the main data signal generated by the main data signal generation unit 34 is output to the LD drive circuit 32. As a result, the LD drive circuit 32 controls the LD 31 so as to modulate the laser beam LB in accordance with the main data signal. As a result, the main data signal is recorded at a position corresponding to the lead-in area 13, the data area 14, and the lead-out area 15 in the recording master 100 (step S31).

Before and after the recording of the main data signal, the BCA signal generation unit 36 synchronizes with the master clock signal (or the recording clock signal obtained by dividing the master clock signal) to record the barcode information 121 to be recorded. A BCA signal is generated by performing modulation in accordance with (step S32). Thereafter, the signal switching unit 33 controls the path so that the BCA signal generated by the BCA signal generation unit 36 is output to the LD drive circuit 32. As a result, the LD drive circuit 32 controls the LD 31 so as to modulate the laser beam LB in accordance with the BCA signal. As a result, the barcode information 121 is recorded at a position corresponding to the prewrite BCA 12 in the recording master 100 (step S33).

As a result of the above operation, the recording master 100 is completed (step S34). Thereafter, the above-described optical disk 10 is duplicated by the stamper device 40 shown in FIG. 10 using the master disk stamper 200 created from the recording master 100 (step S35). Specifically, the stamper device 40 sandwiches the resin substrate 300 serving as the base of the optical disc 10 between the stamper 200 supported by the stamper support 41 and the support base 43. Thereafter, the stamper device 40 is pressed (pressed) from both sides of the stamper support 41 and the support base 43 while being heated using a mold 42 having a heater inside. As a result, grooves (that is, molds such as recording pits P1 and P2) engraved in the stamper 200 are transferred to the surface of the resin substrate 300. Thereafter, the optical disk 10 is completed by cooling the resin substrate 300 and forming a cover layer.

(3) Playback Device Next, with reference to FIGS. 11 to 12, a playback device 50 for playing back the optical disc 10 of the present embodiment will be described. FIG. 11 is a block diagram showing the configuration of a playback apparatus 50 that plays back the optical disk 10 of the present embodiment. FIG. 12 is a flowchart showing an operation flow of the reproducing device 50 of the present embodiment.

As shown in FIG. 11, the playback device 50 includes an optical PU 51 that acquires pit data by irradiating the optical disk 10 with laser light LB, an amplifier 521 that generates a playback signal based on the acquired pit data, and a playback signal. A demodulator 522 that generates a demodulated signal by performing a predetermined demodulating process, and decoding that acquires and decodes audio information and video information by acquiring predetermined information from the demodulated signal and performing decoding A conversion unit 523, a main data decoder 524 that converts the decoded audio information and video information into information of a predetermined format and outputs the information to the outside, a filter (low-pass filter) 541 that cuts a high frequency component of the input pit data, The slicer 542 that binarizes the pit data from which the high frequency component is cut, and the binarized pit data B The BCA data decoder 543 that decodes the A data (specifically, the above-described barcode information 121), and overall control of each of the above components while exchanging necessary control information via the bus, A system controller 53 that generates control information based on the above and a focus servo system circuit 55 that performs the above-described focus servo control are provided.

The light PU 51 emits a laser beam LB having a certain intensity for reproduction, and receives light reflected from the phase pit by a light receiving unit (not shown). Pit data corresponding to the intensity change of the received reflected light ( (Sum signal) is generated and output to the amplifier 521 and the filter 541.

Further, in the optical PU 51, switching of the pit data to the amplifier 521 or the filter 541 is controlled based on the control of the system controller 53. Specifically, pit data is output to the filter 541 when the light PU 51 is irradiating the pre-light BCA 12 with the laser light LB. On the other hand, when the optical PU 51 irradiates the laser light LB to an area other than the prewrite BCA 12 (for example, the lead-in area 13, the data area 14, and the lead-out area 15), the pit data is output to the amplifier 521. .

Note that since the prewrite BCA 12 is an area that is first read by the optical PU 51 after the optical disk 10 is loaded onto the playback device 50, the pit data is normally output to the filter 541 in the initial setting.

The amplifier 521 performs preset amplification processing and waveform shaping processing on the pit data detected by the optical PU 51, generates a reproduction signal, and outputs the reproduction signal to the demodulation unit 522.

The reproduction signal that has been subjected to predetermined processing by the amplifier 521 is input to the demodulation unit 522. The demodulator 522 performs preset demodulation processing on the reproduction signal, and generates encrypted information and content management information in which audio information and video information are encrypted. Further, the demodulation unit 522 outputs the generated encrypted information to the decryption unit 523 and outputs the generated content management information to the outside of the system controller 53 or the playback device 50.

The encryption information generated by the demodulation unit 522 is input to the decryption unit 523. The decryption unit 523 decrypts the encrypted content information by performing a predetermined decryption process on the encrypted information, and outputs the decrypted content information to the main data decoder 524.

The main data decoder 524 receives the decrypted content information (that is, audio information and video information having a predetermined format). The main data decoder 524 demodulates the input audio information and video information having a predetermined format into the original data format, and outputs them to the outside of the playback device 50.

The filter 541 receives pit data detected by the optical PU 51 (that is, pit data recorded in the prewrite BCA 12). The filter 541 cuts high-frequency components from the input pit data and outputs the cut data to the slicer 542. In this embodiment, the filter 541 is a second-order Bessel low-pass filter with a cutoff frequency of 500 kHz in order to eliminate the influence of interference between pit data continuous on the track recorded on the prewrite BCA 12. Is preferred.

The slicer 542 receives pit data from which high frequency components have been cut. The slicer 542 performs binarization processing on the input pit data based on a predetermined level (slice level), acquires bit data, and outputs the acquired bit data to the BCA data decoder 543. To do.

Bit data output from the slicer 542 is input to the BCA data decoder 543. The BCA data decoder 543 performs predetermined demodulation processing and error correction processing on the input bit data to obtain BCA data (that is, barcode information 121 and gap information 122), and uses the BCA data as a system. Output to the controller 53.

The system controller 53 is mainly composed of a CPU (Central Processing Unit) and a memory, and performs control of each part at the time of reproduction of the content information, control of acquisition processing of BCA data described later, and the like. In particular, the BCA data acquired by the BCA data decoder 543 is input to the system controller 53, and the system controller 53 performs setting and control of each unit during reproduction of the optical disc 10 based on the input BCA data.

The playback device 50 having such a configuration operates according to the flowchart shown in FIG. Specifically, the light PU 51 irradiates the pre-light BCA 12 with the laser light LB, thereby reading the BCA data (that is, the barcode information 121) recorded on the pre-light BCA 12 (step S51). Thereafter, the filter 541 cuts the high frequency component of the pit data detected by the optical PU 51 (that is, the pit data recorded in the prewrite BCA 12) (step S52). Thereafter, the slicer 542 performs binarization processing based on a predetermined level (slice level) for the pit data from which the high frequency component is cut, and the BCA data decoder 543 performs binarized bit processing. BCA data (that is, barcode information 121) is acquired by performing predetermined demodulation processing and error correction processing on the data. As a result, the barcode information 121 is reproduced (step S53). Thereafter, the system controller 53 performs setting and control of each unit during reproduction of the optical disc 10 based on the reproduced barcode information 121 (step S54). Thereafter, the optical PU 51 irradiates the lead-in area 13, the data area 14, and the lead-out area 15 with the laser beam LB, whereby the data recorded in the lead-in area 13, the data area 14, and the lead-out area 15. Is read (step S55). Thereafter, the pit data detected by the optical PU 51 is subjected to demodulation processing by the demodulation unit 522, decoding processing by the decoding unit 523, and processing by the main data decoder 524, such as amplification processing and waveform shaping processing by the amplifier 521. As a result, audio information and video information are reproduced.

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 a recording medium accompanied by such a change, a manufacturing apparatus for manufacturing the recording medium, and A method and a reproducing apparatus and method for reproducing a recording medium are also included in the technical idea of the present invention.

10 Optical disk 12 BCA
121 Barcode information 1211 Pit part 1212 Unrecorded part 30 Manufacturing equipment 40 Stamper equipment 50 Playback equipment

Claims

A reproduction information recording area in which reproduction information is recorded;
A control information recording area in which control information for controlling reproduction of the reproduction information is recorded,
A bar code in which a first pit portion in which a plurality of first recording pits are formed and a first unrecorded portion in which the first recording pits are not formed is combined in at least a part of the control information recording area Information is recorded in CAV (Constant Angular Velocity) across multiple recording tracks,
Overwriting information to be overwritten on the first unrecorded part is CAV recorded across a plurality of recording tracks on a part of the first unrecorded part constituting the barcode information,
In the overwriting information, the average level of the signal intensity when the overwriting information is read is equal to or higher than the average level of the signal intensity when the first pit portion is read, and the overwriting information is not overwritten. A recording medium recorded so as to be less than an average level of signal intensity when the first unrecorded portion is reproduced.
2. The recording medium according to claim 1, wherein the overwriting information includes a second pit portion in which a second recording pit is formed.
3. The recording according to claim 2, wherein a length of the second pit portion along the rotation direction of the recording medium is smaller than a length of the first pit portion along the rotation direction of the recording medium. Medium.
The ratio or density occupied by the second pit portion per unit length along the rotation direction of the recording medium is higher than the ratio or density occupied by the first pit portion per unit length along the rotation direction of the recording medium. The recording medium according to claim 2, wherein the recording medium is small.
The period in which the second pit portion appears along the rotation direction of the recording medium is the longest recording pit having the maximum length along the rotation direction of the recording medium among the third recording pits constituting the reproduction information, and The recording medium according to claim 2, wherein the recording medium has a period equal to or shorter than a combination of longest recording spaces corresponding to the longest recording pits.
The length of the second pit portion along the rotation direction of the recording medium is equal to or less than the maximum value of the length along the rotation direction of the recording medium of the third recording pit constituting the reproduction information, and 3. The recording medium according to claim 2, wherein the length of the three recording pits is equal to or greater than a minimum value along the rotation direction of the recording medium.
A manufacturing apparatus for manufacturing a recording medium including a reproduction information recording area and a control information recording area,
First recording means for recording reproduction information in the reproduction information recording area;
Second recording means for recording control information in the control information recording area,
The second recording means includes, as at least a part of the control information, a combination of a first pit portion in which a plurality of first recording pits are formed and a first unrecorded portion in which the first recording pits are not formed The recorded barcode information is recorded across multiple recording tracks by CAV (Constant Angular Velocity),
The second recording means further extends overwritten information over a plurality of recording tracks on a part of the first unrecorded portion constituting the barcode information, overwritten on the first unrecorded portion. To record CAV,
In the second recording means, the average level of signal intensity when the overwriting information is read is equal to or higher than the average level of signal intensity when the first pit portion is read, and the overwriting information is not overwritten. The overwriting information is recorded so as to be less than the average level of the reproduction signal intensity when the first unrecorded portion is read.
8. The manufacturing apparatus according to claim 7, further comprising a duplicating unit that duplicates the recording medium on which the reproduction information and the control information are recorded.
A manufacturing method for manufacturing a recording medium comprising a reproduction information recording area and a control information recording area,
A first recording step of recording reproduction information in the reproduction information recording area;
A second recording step of recording control information in the control information recording area,
In the second recording step, as at least part of the control information, a first pit portion in which a plurality of first recording pits are formed and a first unrecorded portion in which the first recording pits are not formed are combined The recorded barcode information is recorded across multiple recording tracks by CAV (Constant Angular Velocity),
In the second recording step, overwriting information that is overwritten on a part of the first unrecorded portion of the first unrecorded portion constituting the barcode information is overlaid on a plurality of recording tracks. To record CAV,
In the second recording step, the signal intensity average level when the overwriting information is read is equal to or higher than the signal intensity average level when the first pit portion is read, and the overwriting information is not overwritten. The overwriting information is recorded so that the reproduction signal intensity is less than the average level when the first unrecorded portion is read.
A playback device for playing back the recording medium according to claim 1,
First reading means for reading a reproduction signal indicating the reproduction information from the reproduction information recording area;
Second reading means for reading a control signal indicating the barcode information as the control information from the control information recording area;
A low-pass filter that cuts off a high-frequency signal component corresponding to a predetermined cutoff frequency among the control signals read by the second reading unit;
And a reproducing unit that reproduces the bar code information based on the control signal that has passed through the low-pass filter.
11. The reproducing apparatus according to claim 10, wherein the low-pass filter is a second-order Bessel low-pass filter having a cutoff frequency of 500 kHz.
A playback method for playing back the recording medium according to claim 1,
A first reading step of reading a reproduction signal indicating the reproduction information from the reproduction information recording area;
A second reading step of reading a control signal indicating the barcode information as the control information from the control information recording area;
A low-pass filtering step of cutting off a high-frequency signal component corresponding to a predetermined cutoff frequency among the control signals read by the second reading unit;
A reproduction step of reproducing the barcode information based on the control signal that has passed through the low-pass filtering step.