WO2009122566A1

WO2009122566A1 - Reproduction apparatus and method, and computer program

Info

Publication number: WO2009122566A1
Application number: PCT/JP2008/056485
Authority: WO
Inventors: 庄悟宮鍋; 儀央佐々木; 裕行内野
Original assignee: パイオニア株式会社
Priority date: 2008-04-01
Filing date: 2008-04-01
Publication date: 2009-10-08

Abstract

A reproduction apparatus (1) includes detection means (21) for detecting frequencies of appearance of signal components of a plural types of marks and signal components of a plural types of spaces having different run lengths, which are included in a readout signal read out from a recording medium (100), and. determining means (22) for determining whether the record region on the recording medium from which the readout signal has been read out is a defect region or not.

Description

Playback apparatus and method, and computer program

The present invention relates to, for example, a reproduction apparatus and method for reproducing a data pattern recorded on a recording medium, and a technical field of a computer program that causes a computer to function as such a reproduction apparatus.

As such a reproducing apparatus, various apparatuses for reproducing a data pattern by irradiating a recording medium such as an optical disc such as a CD, a DVD, a Blu-ray Disc, etc. with a laser beam are realized. In such a reproduction apparatus, a track on a recording medium is irradiated with laser light, and a reflected light of the irradiated laser light is detected to detect a data pattern composed of marks and spaces. . As a result, the data pattern can be reproduced.

In such a reproducing apparatus, in order to realize a more preferable reproducing operation, a defect area (defect area) on the recording medium is detected and defect management (defect management) not using the detected defect area is performed. . For example, in the configuration disclosed in Patent Document 1, jitter is detected, and a defective area is detected based on whether or not the detected jitter has characteristics capable of withstanding recording or reproduction. In the configuration disclosed in Patent Document 2, a defect area is detected based on a change in jitter, asymmetry, error rate, envelope waveform, or the like.

JP 2002-74668 A JP 2000-251254 A

However, according to the study by the inventors of the present application, it is not possible to suitably detect all the defective areas that can occur on the recording medium by the detection operation based only on jitter, asymmetry, error rate, envelope waveform change, etc. It has been revealed. In particular, in a defect region where the transmittance of laser light has fluctuated from the original transmittance, such as a defect region to which a fingerprint or the like is attached, it becomes difficult to irradiate the laser beam with the originally intended power. For this reason, it is impossible to record the run-length mark that is originally intended. This is particularly noticeable in marks with relatively short run lengths. As a result, for example, a mark that should originally be recorded so that the run length is 2T or 3T may be recorded as a mark with a run length of 2T or less than 3T. In this case, at the time of reproduction, the signal component of the mark having a run length of 2T or less than 3T may not intersect with the zero level (or the binarized slice level). As a result, a mark with a run length of 2T or less than 3T does not contribute to the calculation of jitter and does not deteriorate the jitter. Therefore, the configurations disclosed in Patent Document 1 and Patent Document 2 described above have a technical problem that it is difficult or impossible to detect such a recording area as a defective area. However, since it remains the same that the fingerprint or the like is attached, it is needless to say that it is preferably detected as a defective area. Even if the recorded mark or space is recorded with the original run length, the same problem may occur when a fingerprint is attached during reproduction.

The present invention has been made in view of, for example, the above-described conventional problems, and an object of the present invention is to provide a playback apparatus and method that can suitably detect a defective area on a recording medium, for example, and a computer program. .

In order to solve the above problems, the reproducing apparatus of the present invention includes a plurality of types of mark signal components included in a read signal obtained by reading a data pattern from a recording medium and having different run lengths, and the read signal. The detection means for detecting the appearance frequency of at least one signal component of a plurality of types of signal components included and having different run lengths, and the reading based on the amount of change in the appearance frequency of the at least one signal component Determination means for determining whether or not the recording area on the recording medium from which the signal has been read is a defective area.

In order to solve the above problems, the reproducing method of the present invention includes a plurality of types of mark signal components included in a read signal obtained by reading a data pattern from a recording medium and having different run lengths, and the read signal. The detection step of detecting an appearance frequency of at least one signal component of a plurality of types of signal components included and having different run lengths, and the reading based on a change amount of the appearance frequency of the at least one signal component A determination step of determining whether or not the recording area on the recording medium from which the signal has been read is a defective area.

In order to solve the above-described problems, a computer program according to the present invention includes a plurality of types of mark signal components included in a read signal obtained by reading a data pattern from a recording medium and having different run lengths, and the read signal. The detection means for detecting the appearance frequency of at least one signal component of a plurality of types of signal components included and having different run lengths, and the reading based on the amount of change in the appearance frequency of the at least one signal component A computer program for playback control that controls a computer provided in a playback device, comprising: a determination unit that determines whether or not a recording area on the recording medium from which a signal has been read is a defective area; To function as the detection means and the determination means.

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

FIG. 2 is a block diagram conceptually showing the basic structure of a reproducing apparatus in the example. 6 is a flowchart conceptually showing a flow of operations of the reproducing apparatus in the example. It is a table | surface which shows the reference | standard frequency of each mark and each space. It is a figure which shows the appearance frequency of the shortest mark in each of a normal area | region and a defect area | region with a jitter. It is a graph which shows the state of the read signal in each of a normal area | region and a defect area | region with a binarization slice level. It is a figure which shows the appearance frequency of each mark and each space in each of a normal area | region and a defect area | region. It is a graph which shows the appearance frequency of the space in each of a normal area | region and a defect area | region. It is a graph which shows the appearance frequency of the mark in each of a normal area | region and a defect area | region. It is a graph which shows the difference of the appearance frequency of each of the mark whose run length is 9T and the space whose run length is 9T in the sync pattern in each of the normal area and the defect area. FIG. 10 is a block diagram conceptually showing the structure of a reproducing apparatus in a modified example.

Explanation of symbols

1, 2 Playback device 10 Spindle motor 11 Pickup 12 HPF
13 A / D converter 14 Pre-equalizer 15 Limit equalizer 16 Binary circuit 17 Decoding circuit 21 T frequency detection circuit 22 Defective area detection circuit

Hereinafter, as the best mode for carrying out the invention, description will be given of an embodiment according to a playback apparatus and method and a computer program of the present invention.

(Embodiment of playback device)
The embodiment of the reproducing apparatus of the present invention includes signal components of a plurality of types of marks that are included in a read signal obtained by reading a data pattern from a recording medium and have different run lengths, and are included in the read signal and the run signal. The read signal is read on the basis of detection means for detecting an appearance frequency of at least one signal component of signal components of a plurality of types of spaces having different lengths, and a change amount of the appearance frequency of the at least one signal component. Determining means for determining whether or not the recording area on the recording medium is a defective area.

According to the embodiment of the reproducing apparatus of the present invention, the appearance frequency of at least one signal component of a plurality of types of mark signal components and a plurality of types of space signal components is detected by the operation of the detection means. For example, when the recording medium is a DVD, marks having run lengths from 3T to 11T and 14T are examples of “plural types of marks”. Similarly, for example, when the recording medium is a Blu-ray Disc, a mark whose run length is 2T to 9T is an example of “a plurality of types of marks”. Similarly, for example, when the recording medium is a DVD, spaces with run lengths from 3T to 11T and 14T are examples of “plural types of spaces”. Similarly, for example, when the recording medium is a Blu-ray Disc, a space with a run length of 2T to 9T is an example of “a plurality of types of spaces”.

Thereafter, by the operation of the determination unit, the change amount of the appearance frequency detected by the detection unit (for example, the change amount of the appearance frequency itself, the change amount with respect to the predetermined reference frequency, the difference from the predetermined reference frequency, Whether or not the recording area on the recording medium is a defective area is determined based on a magnitude relationship with respect to the reference frequency, a ratio with respect to the predetermined reference frequency, a deviation rate with respect to the predetermined reference frequency, and the like. That is, it is determined whether or not the recording area from which the read signal including at least one signal component whose appearance frequency has been detected by the detection unit is read is a defective area. Here, the “reference frequency” may typically indicate, for example, a predetermined fixed value, or each of a plurality of types of marks and a plurality of types of spaces when a normal recording operation is performed. The appearance frequency, etc. may be shown.

Here, the above-described detection operation and determination operation for a read signal obtained in a defect region in which the transmittance with respect to laser light has fluctuated from the original transmittance, such as a defect region to which a fingerprint or the like is attached, will be described. . In such a defective area, at the time of recording, it may become impossible to record the mark of the run length originally intended. In other words, due to the lack of energy of the laser light applied to the recording medium, for example, the run length is originally minT (where “minT” indicates the shortest run length predetermined by the standard of the recording medium). The mark to be recorded may be recorded as a mark having a run length of less than minT. The recording of a mark having a run length of less than minT also leads to reading of a space having a run length of less than minT together with a mark having a run length of less than minT during reproduction. Furthermore, at the time of reproduction, the signal component of the mark or space whose run length is less than minT is shifted in the amplitude direction, so that it may not intersect with the zero level (or the binarized slice level). As a result, data patterns originally recorded as predetermined run-length marks and spaces are reproduced as a series of spaces. If such a space is connected to another run-length mark or space, the run-length of another run-length mark or space is also changed. Accordingly, the frequency of appearance of the signal component of each mark or the frequency of appearance of the signal component of each space included in the read signal obtained in the defect area can vary. More specifically, the frequency of appearance of the signal component of each mark or the frequency of appearance of the signal component of each space included in the read signal obtained in the defect area is included in the read signal obtained in a normal area without defects. The frequency of appearance of the signal component of each mark or the frequency of appearance of the signal component of each space (for example, the reference frequency) may be different. In this case, since the signal component of the mark or space whose run length is less than minT does not intersect with the zero level (or the binarized slice level), the jitter does not deteriorate. In the configuration for detecting the defective area, the defective area cannot be detected. However, according to the present embodiment, the defect area can be suitably detected by taking into account the change amount of the appearance frequency detected by the detecting means by the operation of the determining means. In particular, it is possible to suitably detect a defective area in which the transmittance of the laser light has fluctuated from the original transmittance, such as a defective area to which a fingerprint or the like is attached.

As described above, according to the reproducing apparatus according to the present embodiment, it is possible to appropriately identify a defective region by referring to the appearance frequency of at least one signal component among a plurality of types of marks and a plurality of types of spaces having different run lengths. Can be detected. In particular, it is possible to suitably detect a defective area in which the transmittance of the laser light has fluctuated from the original transmittance, such as a defective area to which a fingerprint or the like is attached. Therefore, the defect area detection accuracy can be improved as compared with the configuration in which the defect area is detected based only on jitter.

In one aspect of the reproducing apparatus of the present invention, the detecting means detects the appearance frequency of the signal component of the mark having the shortest run length, and the determining means determines the appearance frequency of the signal component of the mark having the shortest run length. Based on the amount of change, it is determined whether or not the recording area on the recording medium from which the read signal has been read is a defective area.

According to this aspect, the mark having the shortest run length (for example, the recording medium is significantly affected) in the defect area in which the transmittance with respect to the laser beam fluctuates from the original transmittance, such as the defect area to which the fingerprint or the like is attached. In the case of a DVD, the run length is a 3T mark. For example, when the recording medium is a Blu-ray Disc, the defect area can be detected based on the appearance frequency of the run length 2T mark). it can. Therefore, the defect area can be detected with higher accuracy or more easily.

In another aspect of the embodiment of the reproducing apparatus of the present invention, the detecting means detects the appearance frequency of the signal component of the space having the shortest run length, and the determining means is the signal component of the space having the shortest run length. Whether the recording area on the recording medium from which the read signal has been read is a defective area is determined based on the change amount of the appearance frequency of.

According to this aspect, the space having the shortest run length (for example, the recording medium is significantly affected) in the defect area where the transmittance with respect to the laser beam fluctuates from the original transmittance, such as the defect area to which the fingerprint or the like is attached. In the case of a DVD, the run length is a 3T space. For example, when the recording medium is a Blu-ray Disc, the defect area can be detected based on the appearance frequency of the run length is a 2T space). it can. Therefore, the defect area can be detected with higher accuracy or more easily.

As described above, in the aspect of the reproducing apparatus that determines whether or not the recording area is a defect area based on the change amount of the appearance frequency of the signal component of the mark or space having the shortest run length, the determination means includes the appearance frequency. May be determined that the recording area on the recording medium from which the read signal has been read is a defective area when is smaller than a predetermined ratio with respect to a predetermined reference frequency.

As described above, in the defect area where the transmittance with respect to the laser beam is fluctuated from the original transmittance, such as the defect area to which the fingerprint or the like is attached, at the time of recording, the originally intended run length is as described above. The mark or space cannot be recorded. As a result, a mark or space to be recorded as a mark or space with the shortest run length may be recorded as a mark or space with a shorter run length. As a result, the appearance frequency of the mark or space having the shortest run length is reduced. Therefore, when the appearance frequency is smaller than the reference frequency by a predetermined ratio or more, it is possible to preferably detect the defect area by determining that the defect area is a defect area.

In another aspect of the embodiment of the reproducing apparatus of the present invention, the detecting means detects an appearance frequency of a signal component having a relatively long run length included in the read signal, and the determining means Whether or not the recording area on the recording medium from which the read signal has been read is a defective area is determined based on the change amount of the appearance frequency of the signal component in the space having a relatively long run length.

According to this aspect, a space having a relatively long run length (for example, if the recording medium is a DVD), the appearance frequency may vary due to a decrease in the appearance frequency of the mark or space having the shortest run length. If the run lengths are 7T to 11T and 14T spaces and the recording medium is a Blu-ray Disc, the defect area can be suitably detected based on the appearance frequency of the signal components of the run lengths 6T to 9T.

In another aspect of the embodiment of the reproducing apparatus of the present invention, the detecting means detects an appearance frequency of a signal component of a space having the longest run length included in the read signal, and the determining means includes the run length. Whether or not the recording area on the recording medium from which the read signal is read is a defective area is determined based on the change amount of the appearance frequency of the signal component of the longest space.

According to this aspect, a space having the longest run length that can vary due to a decrease in the appearance frequency of the mark or space having the shortest run length (for example, a run length if the recording medium is a DVD). Is a space of 11T or 14T, and if the recording medium is a Blu-ray Disc, the defect area can be suitably detected based on the appearance frequency of signal components having a run length of 8T or 9T.

As described above, in the aspect of the reproducing apparatus that determines whether or not the recording area is a defective area based on the change amount of the appearance frequency of the signal component having the relatively long or longest run length, the determination unit includes the determination unit When the appearance frequency is greater than a predetermined reference frequency by a predetermined ratio or more, the recording area on the recording medium from which the read signal is read may be determined to be a defective area.

As described above, in a defective area where the transmittance with respect to the laser beam has fluctuated from the original transmittance, such as a defective area to which a fingerprint or the like is attached, during recording, the originally intended run is performed as described above. It becomes impossible to record length marks or spaces. As a result, a mark or space to be recorded as a mark or space with the shortest run length may be recorded as a mark or space with a shorter run length. Due to this, at the time of reproduction, a space with a shorter run length may be treated as a data pattern integrally connected to other spaces. As a result, the appearance frequency of a space having a relatively long or long run length increases. Therefore, when the appearance frequency is larger than the reference frequency by a predetermined ratio or more, it is possible to detect the defect region suitably by determining that the defect region is a defect region.

In another aspect of the embodiment of the reproducing apparatus of the present invention, the detection means includes a violation run length mark different from a run length included in the read signal and predetermined by a standard, and the violation run length. The frequency of appearance of at least one signal component of the space is detected, and the determination unit is configured to read the reading based on the amount of change in the frequency of appearance of the signal component of at least one of the violation run-length mark and the violation run-length space. It is determined whether or not the recording area on the recording medium from which the signal has been read is a defective area.

According to this aspect, a mark or space to be recorded as a mark or space with the shortest (or longest) run length is a shorter or longer run length (i.e., a violation run length, for example, a record If the medium is a DVD, the run length may be 2T or less, 12T, 13T, or 15T or more, and if the recording medium is a Blu-ray Disc, the run length may be 1T or less or 10T or more). In consideration of this, it is possible to detect the defect area suitably.

As described above, in the aspect of the reproducing apparatus that determines whether or not the region is a defective region based on the change amount of the appearance frequency of at least one signal component of the violation run-length mark and space, the determination unit includes the appearance frequency The recording area on the recording medium from which the reading signal is read may be determined to be a defective area when the ratio is larger than a predetermined ratio with respect to a predetermined reference frequency.

As described above, in the defect area where the transmittance with respect to the laser beam is fluctuated from the original transmittance, such as the defect area to which the fingerprint or the like is attached, at the time of recording, the originally intended run length is as described above. The mark or space cannot be recorded. As a result, the appearance frequency of violation run-length marks or spaces increases. Therefore, when the appearance frequency is larger than the reference frequency by a predetermined ratio or more, it is possible to detect the defect region suitably by determining that the defect region is a defect region.

In another aspect of the embodiment of the reproducing apparatus of the present invention, a sync pattern that includes each of the predetermined run-length mark and the predetermined run-length space substantially equally is recorded on the recording medium, and the detection means Detects the appearance frequency of the signal component of the mark of the predetermined run length included in the read signal and the signal component of the space of the predetermined run length included in the read signal, and the determination means The recording area on the recording medium from which the read signal is read is defective based on the amount of change in the appearance frequency of the signal component of the mark of the predetermined run length with respect to the appearance frequency of the signal component of the space of the predetermined run length. It is determined whether it is an area.

The sync pattern includes a predetermined run-length mark and a predetermined run-length space approximately evenly when a normal recording operation is performed, while a predetermined run-length mark and a predetermined run-length when recorded in a defective area. Each of the run length spaces may be unequal. Therefore, according to this aspect, the defective area can be suitably detected by reading the sync pattern.

In another aspect of the embodiment of the reproducing apparatus of the present invention, the amplitude level of the read signal is limited by a predetermined amplitude limit value to obtain an amplitude limit signal, and high-frequency emphasis is applied to the amplitude limit signal. An amplitude limiting filtering unit that obtains an equalization correction signal by performing filtering processing is further provided, wherein the determination unit includes the frequency of appearance of the at least one signal component included in the equalization correction signal. Whether or not the recording area on the recording medium from which the read signal has been read is a defective area is determined based on the amount of change in the appearance frequency of at least one signal component included in.

According to this aspect, the amplitude level of the read signal is limited by the operation of the amplitude limit filtering means. Specifically, the signal level of the read signal whose amplitude level is larger than the upper limit or lower limit of the amplitude limit value is limited to the upper limit or lower limit of the amplitude limit value. On the other hand, the amplitude level of the signal component whose amplitude level is below the upper limit and below the lower limit of the amplitude limit value in the read signal is not limited. The high-frequency emphasis filtering process is further performed on the read signal (that is, the amplitude limit signal) on which the amplitude level is thus limited. As a result, an equalization correction signal is acquired.

This enhances the amplitude of the mark or space whose run length is relatively or shortest included in the equalization correction signal. As a result, the appearance frequency of each mark or each space included in the equalization correction signal can be brought close to the original appearance frequency. Therefore, the defect region can be suitably detected by comparing the appearance frequency of each mark or each space included in the read signal with the appearance frequency of each mark or each space included in the equalization correction signal. it can.

In particular, since it is not necessary to previously have the reference frequency in the form of a table or the like, the above-described operation can be performed on a wide variety of recording media or unknown recording media. Therefore, it is possible to detect a defective area in a variety of recording media or unknown recording media.

(Embodiment of reproduction method)
The embodiment according to the reproducing method of the present invention includes a plurality of types of mark signal components included in a read signal obtained by reading a data pattern from a recording medium and having different run lengths, and included in the read signal and the run signal. The read signal is read based on a detection step of detecting an appearance frequency of at least one signal component of signal components of a plurality of types of spaces having different lengths, and a change amount of the appearance frequency of the at least one signal component. And a determination step of determining whether or not the recording area on the recording medium is a defective area.

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

Incidentally, in response to the various aspects in the embodiment of the playback apparatus of the present invention described above, the embodiment of the playback method of the present invention can also take various aspects.

(Embodiment of computer program)
Embodiments according to the computer program of the present invention include signal components of a plurality of types of marks that are included in a read signal obtained by reading a data pattern from a recording medium and have different run lengths, and are included in the read signal and the run signal. The read signal is read on the basis of detection means for detecting an appearance frequency of at least one signal component of signal components of a plurality of types of spaces having different lengths, and a change amount of the appearance frequency of the at least one signal component. Further, a reproducing apparatus comprising: a determination unit that determines whether or not the recording area on the recording medium is a defective area (that is, the embodiment according to the above-described reproducing apparatus of the present invention (including various aspects thereof)) A computer program for controlling playback that controls a computer provided in the computer, the computer comprising the detection means and the detection means To function as a constant means.

According to the embodiment of the computer program of the present invention, the computer program is read from a recording medium such as a ROM, a CD-ROM, a DVD-ROM, and a hard disk that stores the computer program, and executed. If the computer program is downloaded to a computer via communication means and then executed, the above-described embodiment of the playback apparatus of the present invention can be realized relatively easily.

Incidentally, in response to the various aspects of the embodiment of the playback apparatus of the present invention described above, the embodiment of the computer program of the present invention can also adopt various aspects.

Embodiments according to the computer program product of the present invention are included in a read signal obtained by reading a data pattern from a recording medium and are included in the read signal and a plurality of types of mark signal components having different run lengths. Based on the detection means for detecting the appearance frequency of at least one signal component of the signal components of a plurality of types of spaces having different run lengths, and the read signal is read based on the amount of change in the appearance frequency of the at least one signal component. And a determination unit that determines whether or not the recording area on the recording medium is a defective area (that is, the above-described embodiment of the reproduction apparatus of the present invention (including various aspects thereof) The program instructions executable by the computer provided in the above are clearly embodied, and the computer includes the detection means and the detection means. To function as a constant means.

According to the embodiment of the computer program product of the present invention, if the computer program product is read into a computer from a recording medium such as a ROM, a CD-ROM, a DVD-ROM, and a hard disk storing the computer program product, or For example, if the computer program product, which is a transmission wave, is downloaded to a computer via communication means, the above-described embodiment of the playback apparatus of the present invention can be implemented relatively easily. More specifically, the computer program product may be configured by computer-readable code (or computer-readable instructions) that functions as the above-described embodiment of the playback apparatus of the present invention.

Incidentally, in response to the various aspects of the embodiment of the playback apparatus of the present invention described above, the embodiment of the computer program product of the present invention can also adopt various aspects.

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

As described above, according to the embodiment of the reproducing apparatus of the present invention, the detection device and the determination device are provided. According to the embodiment of the reproduction method of the present invention, the method includes a detection step and a determination step. According to the embodiment of the computer program of the present invention, the computer is caused to function as the embodiment of the playback apparatus of the present invention. Therefore, a defective area on the recording medium can be suitably detected.

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

(1) Configuration of Playback Device First, with reference to FIG. 1, description will be given of an embodiment according to the playback device of the present invention. FIG. 1 is a block diagram conceptually showing the basic structure of the reproducing apparatus in the example.

As shown in FIG. 1, the reproducing apparatus 1 according to the present embodiment includes a spindle motor 10, a pickup (PU: PickＰUp) 11, an HPF (High Pass Filter) 12, an A / D converter 13, An equalizer (Pre Equalizer) 14, a binarization circuit 16, a decoding circuit 17, a T frequency detection circuit 21, and a defect area detection circuit 22 are provided.

The pickup 11 photoelectrically converts reflected light when the recording surface of the optical disk 100 rotated by the spindle motor 10 is irradiated with the laser beam LB, and generates a read signal _RRF .

The HPF 12 removes the low frequency component of the read signal R _RF output from the pickup, and outputs the read signal R _HC obtained as a result to the A / D converter 13.

The A / D converter 13 samples the read signal R _HC in accordance with a sampling clock output from a PLL (Phased Lock Loop) (not shown) or the like, and outputs the read sample value series RS obtained as a result to the pre-equalizer 14. To do.

Pre-equalizer 14 removes intersymbol interference based on the transmission characteristics of the composed information reading system from the pickup 11 and the optical disc 100, and outputs the resulting read sample value series RS _C to the binary circuit 16.

Binarizing circuit 16, read binarizes to the sample value series RS _C, and outputs a binary signal obtained as a result of the decoding circuit 17 and to each of T frequency detection circuit 21.

The decoding circuit 17 performs a decoding process on the binarized signal and outputs a reproduction signal obtained as a result to an external reproduction device such as a display or a speaker. As a result, a data pattern (for example, video data or audio data) recorded on the optical disc 100 is reproduced.

The T frequency detection circuit 21 constitutes a specific example of the “detection means” in the present invention, and detects the appearance frequency of marks and spaces included in the binarized signal for each run length. For example, when the optical disc 100 is a DVD, the T frequency detection circuit 21 detects the appearance frequencies of marks with run lengths of 3T to 11T and 14T and spaces with run lengths of 3T to 11T and 14T. Alternatively, for example, when the optical disc 100 is a Blu-ray Disc, the T frequency detection circuit 21 detects the appearance frequency of each of a mark having a run length of 2T to 9T and a space having a run length of 2T to 9T.

The defective area detection circuit 22 constitutes one specific example of the “determination means” in the present invention, and the T frequency detection circuit 21 is based on the appearance frequency of each mark and each space detected by the T frequency detection circuit 21. It is determined whether or not the recording area on the optical disc 100 on which the data pattern corresponding to the binarized signal that is the target of the detection operation is a defective area.

(2) Operation of Playback Device Next, with reference to FIG. 2, the operation of the playback device 1 according to the present embodiment will be described. FIG. 2 is a flowchart conceptually showing a flow of operations of the reproducing apparatus 1 in the example.

As shown in FIG. 2, the data pattern recorded on the optical disc 100 is reproduced (step S101). That is, the signal _{R RF} read by the pickup 11 is generated, the read signal _{R HC} from the read signal _{R RF} by HPF12 is generated, A / D converter 13 by the reading from the read signal _{R HC} sample value series RS is generated, pre The equalizer 14 generates a read sample value series RS _C from the read sample value series RS, the binarization circuit 16 generates a binarized signal from the read sample value series RS _C , and the decoding circuit 17 decodes the binarized signal. Processing is performed.

Following or in parallel with the processing of step S101, the appearance frequency (T frequency) of marks and spaces included in the binarized signal is detected for each run length by the operation of the T frequency detection circuit 21 (step S101). S102). Here, for example, it is preferable to detect the appearance frequency for each predetermined reproduction period.

Subsequently, by the operation of the defect area detection circuit 22, the appearance frequency of the mark with the shortest run length detected in step S102 (hereinafter, referred to as “shortest mark” as appropriate) is set to be higher than the reference frequency (reference appearance frequency). It is determined whether or not it is smaller than the ratio (step S103). That is, if the optical disc 100 is a DVD, it is determined whether or not the appearance frequency of the mark with the run length of 3T is smaller than the reference frequency of the mark with the run length of 3T by a predetermined ratio or more. Similarly, if the optical disc 100 is a Blu-ray Disc, it is determined whether the appearance frequency of a mark with a run length of 2T is smaller than a reference frequency of a mark with a run length of 2T by a predetermined ratio or more.

Here, the reference frequency is preferably an appearance frequency of each mark and each space when a predetermined data pattern or a random data pattern is recorded in a recording area having no defect on the optical disc 100. For example, the reference frequency may be stored in advance in a memory or the like included in the playback apparatus 1, may be recorded on the optical disc 100, or may be appropriately generated by the playback apparatus 1. Therefore, it is preferable that the defective area detection circuit 22 performs the determination operation in step S103 by reading the reference frequency stored in advance or recorded in advance.

In addition, as a predetermined ratio, the appearance frequency of each mark and each space in a defective area that affects recording or reproduction, the appearance frequency of each mark and each space in a defective area that does not affect recording or reproduction, or normal It is preferable that an appropriate value is determined in advance experimentally, empirically, or using a simulation while considering the appearance frequency (that is, the reference frequency) of each mark and each space in the recording area. For example, the ratio of the appearance frequency of each mark and each space in the defect area that affects recording or reproduction to the reference frequency is an example of the predetermined ratio. Alternatively, the value of the boundary between the appearance frequency of each mark and each space in the defect area that affects recording or reproduction and the appearance frequency of each mark and each space in the defect area that does not affect recording or reproduction, relative to the reference frequency The ratio is another example of the predetermined ratio. More specifically, for example, “50% (or several tens to several tens of percent)” is an example of the predetermined ratio. However, the predetermined ratio is not limited to this.

Here, the reference frequency of each mark and each space will be described with reference to FIG. FIG. 3 is a table showing the reference frequency of each mark and each space. In FIG. 3, as a specific example of the optical disc 100, a DVD in which data patterns are recorded using marks and spaces with run lengths from 3T to 11T and 14T, and marks and spaces with run lengths from 2T to 9T. The Blu-ray Disc that records the data pattern using the will be described. Further, since a mark of a certain run length is recorded on the optical disc 100 in a pair with a space of the same run length, in FIG. 3, the appearance frequency of each mark and space is shown as a common value.

FIG. 3A shows a reference frequency (T appearance) of a run length mark or space in a 2 ECC block that does not take the run length into consideration when a random data pattern is recorded on a DVD which is a specific example of the optical disc 100. Probability). As shown in FIG. 3A, the reference frequency of a mark or space with a run length of 3T is about 32%, the reference frequency of a mark or space with a run length of 4T is about 24%, and the run length is 5T. The standard frequency of a mark or space of about 17%, the standard frequency of a mark or space of 6T run length is about 11.5%, and the standard frequency of a mark or space of 7T run length is about 7% Yes, the reference frequency of a mark or space with a run length of 8T is about 4%, the reference frequency of a mark or space with a run length of 9T is about 2%, and the reference frequency of a mark or space with a run length of 10T is The reference frequency for a mark or space with a run length of 11T is about 0.24%, and the mark or space with a run length of 14T. The standard frequency is about 0.3%.

FIG. 3A shows a reference frequency in consideration of the run length of each run length mark or space in the 2 ECC block when a random data pattern is recorded on a DVD which is a specific example of the optical disc 100. Sample appearance probability) is shown. As shown in FIG. 3A, the reference frequency of a mark or space with a run length of 3T is about 20%, the reference frequency of a mark or space with a run length of 4T is about 20%, and the run length is 5T. The mark or space reference frequency is about 18%, the run length 6T mark or space reference frequency is about 15%, the run length 7T mark or space reference frequency is about 11%, The reference frequency of a mark or space with a run length of 8T is about 7.3%, the reference frequency of a mark or space with a run length of 9T is about 4.5%, and the reference frequency of a mark or space with a run length of 10T The frequency is about 2.9%, the standard frequency of a mark or space with a run length of 11T is about 0.56%, and the mark or space with a run length of 14T. The standard frequency of over scan is about 0.94%.

FIG. 3B shows a reference frequency that does not consider the run length of each run length mark or space in one ECC block when a random data pattern is recorded on a Blu-ray Disc that is a specific example of the optical disc 100. (T appearance probability) is shown. As shown in FIG. 3B, the reference frequency of a mark or space with a run length of 2T is about 38%, the reference frequency of a mark or space with a run length of 3T is about 25%, and the run length is 4T. The mark or space reference frequency is about 16%, the run length 5T mark or space reference frequency is about 10%, the run length 6T mark or space reference frequency is about 6%, The reference frequency of a mark or space with a run length of 7T is about 3%, the reference frequency of a mark or space with a run length of 8T is about 1.6%, and the reference frequency of a mark or space with a run length of 9T is About 0.35%.

In FIG. 3B, the run length of each run length mark or space in one ECC block when a random data pattern is recorded on a Blu-ray Disc, which is a specific example of the optical disc 100, is considered. Reference frequency (sample appearance probability) is shown. As shown in FIG. 3B, the reference frequency of a mark or space with a run length of 2T is about 23%, the reference frequency of a mark or space with a run length of 3T is about 22%, and the run length is 4T. The mark or space reference frequency is about 19%, the run length 5T mark or space reference frequency is about 15%, the run length 6T mark or space reference frequency is about 10%, The reference frequency of a mark or space with a run length of 7T is about 6%, the reference frequency of a mark or space with a run length of 8T is about 3.9%, and the reference frequency of a mark or space with a run length of 9T is About 0.93%.

The reference frequency that does not consider the run length is a reference frequency in which the weight in calculating the reference frequency of the mark or space of each run length is the same in each run length. That is, when one mark or space of a certain run length appears, the reference frequency when the number of appearances is counted as one is shown. On the other hand, the reference frequency in consideration of the run length is a reference frequency on which the weight in calculating the reference frequency of the mark or space of each run length depends on the run length. That is, when one mark or space of a certain run length appears, the reference frequency in the case where the number of appearances is counted by the number corresponding to the run length is shown. In consideration of the existence of two types of reference frequencies in this way, the T frequency detection circuit 21 has one of two types of appearance frequencies (that is, an appearance frequency not considering run length and an appearance frequency considering run length). Or it is preferable to detect both. Moreover, it is preferable that the defective area detection circuit 22 determines whether or not the appearance frequency not considering the run length is smaller than the reference frequency not considering the run length by a predetermined ratio or more. Similarly, it is preferable that the defective area detection circuit 22 determines whether or not the appearance frequency considering the run length is smaller than the reference frequency considering the run length by a predetermined ratio or more.

In FIG. 2 again, when it is determined in step S103 that the appearance frequency of the shortest mark is not lower than the reference frequency by a predetermined rate (step S103: No), the data pattern including the shortest mark is read. It is determined that the recorded area is not a defective area.

Thereafter, it is determined whether or not to end the reproduction operation (step S105). As a result of the determination in step S105, when it is determined not to end the reproduction operation (step S105: No), the process returns to step S101, and the operation after step S102 is repeated while continuing the reproduction operation. On the other hand, as a result of the determination in step S105, when it is determined that the reproduction operation is to be terminated (step S105: Yes), the reproduction operation is terminated.

On the other hand, as a result of the determination in step S103, when it is determined that the appearance frequency of the shortest mark is smaller than the reference frequency by a predetermined ratio (step S103: Yes), the recording in which the data pattern including the shortest mark is read is recorded. It is determined that the area is a defective area (step S104). Therefore, the recording area is set as a defective area, and other defect processing (for example, processing for saving a data pattern recorded in the defective area to another recording area) is performed as necessary. Thereafter, the process proceeds to step S105. In the present embodiment, the recording area in which the transmittance of the laser light has changed from the original transmittance, such as a recording area to which a fingerprint or the like is attached, will be described as an example of the defective area. Of course, it is needless to say that the defect region may be caused by other factors.

However, when it is determined that the appearance frequency of the shortest mark is smaller than the reference frequency by a predetermined ratio, it may be further determined whether or not the jitter is equal to or greater than a predetermined value. That is, it may be configured to additionally determine whether or not the region is a defect region based on jitter.

Next, the appearance frequency of the shortest mark in the defect area will be described with reference to FIGS. FIG. 4 is a diagram showing the appearance frequency of the shortest mark in each of the normal region and the defect region together with the jitter. FIG. 5 shows the state of the read signal R _{RF in} each of the normal region and the defect region. It is a graph shown with a value-ized slice level. In FIG. 4, an example in which a Blu-ray Disc is used as the optical disc 100 will be described.

As shown in FIG. 4, the appearance frequency of the shortest mark (that is, a mark having a run length of 2T) in the defect area to which a fingerprint or the like is attached is the appearance frequency of the shortest mark in a normal area (that is, an area where there is no defect such as a fingerprint). It is smaller than the frequency. Here, depending on the attachment state of the fingerprint, the jitter may deteriorate (see fingerprint state 1) or the jitter may not deteriorate (or be improved) (see fingerprint state 2). The reason for this will be described with reference to FIG.

As shown on the left side of FIG. 5, the shortest mark can be suitably recorded in the normal area. For this reason, the signal waveform corresponding to each mark and each space included in the read signal R _RF preferably crosses the binarized slice level. Therefore, the read signal R _RF in this state is not determined to be a defective region even if determination based on either jitter or appearance frequency is performed.

Subsequently, as shown in the center of FIG. 5, in the defect region corresponding to the fingerprint state 1, the transmittance of the laser light is reduced due to the adhesion of the fingerprint. Therefore, when recording a data pattern in such a defective area, it becomes impossible to give the recording surface of the optical disc 100 the energy necessary for recording the mark of the run length that is originally intended. . This is particularly noticeable when a mark with a short run length is recorded. For this reason, for example, a mark that should originally be recorded as a mark having a run length of 2T may be recorded as a mark having a run length of 1T. That is, a relatively short mark is recorded. Therefore, the appearance frequency of the shortest mark in the defect area is reduced. In addition, in this case, the read signal R _RF obtained in the defect area corresponding to the fingerprint state 1 is particularly shifted to the signal component side corresponding to the space (that is, the upper side in FIG. 5). Assume that a signal component of the state is obtained. In this case, the jitter of the signal component corresponding to the shortest mark is deteriorated. As a result, as shown in FIG. 4, the jitter (that is, total jitter) of the read signal R _RF as a whole deteriorates.

On the other hand, as shown on the right side of FIG. 5, in the defect area corresponding to the fingerprint state 2 as well, for example, a mark that should originally be recorded with a run length of 2T is recorded as a mark with a run length of 1T. It can end up. Therefore, the appearance frequency of the shortest mark in the defect area is reduced. In addition, in this case, the read signal R _RF obtained in the defect region corresponding to the fingerprint state 2 is such that the signal component corresponding to the shortest mark is a space until the signal component corresponding to the shortest mark does not intersect the binarized slice level. It is assumed that a signal component shifted to the signal component side corresponding to is obtained. In this case, the jitter of the signal component corresponding to the shortest mark is no longer contributing to the calculation of jitter as the entire read signal R _RF. Therefore, as shown in FIG. 4, the jitter of the read signal R _RF as a whole is not deteriorated.

In the configuration in which the defect area is detected using only jitter (in other words, without considering the appearance frequency of each mark and each space), the defect area corresponding to the fingerprint state 2 cannot be detected. However, according to the present embodiment, since the defect area is detected based on the appearance frequency of each mark and each space, the defect area corresponding to the fingerprint state 2 can be suitably detected. In addition, since the defective area is detected based on the appearance frequency of the shortest mark that is easily affected by a fingerprint or the like, the defective area can be detected with higher accuracy or more easily.

In the above description, an example in which a defective area is detected based on the appearance frequency of the shortest mark is described. However, as shown in FIGS. 6A and 6B, not only the shortest mark but also the frequency of appearance of a shortest run length space or another run length mark or space is defined as a normal region and a defective region. Can be different between. Here, FIG. 6A is a diagram showing the appearance frequency of each mark recorded with a normal recording power and a relatively low recording power, and FIG. 6B is a diagram showing a normal recording power and a relative recording power. It is a figure which shows the appearance frequency of each space recorded with low recording power. Therefore, the defect area may be detected based on the frequency of appearance of the shortest run length or other run length marks or spaces. For example, the appearance frequency of the space having the shortest run length in the defect area may be smaller than the appearance frequency (that is, the reference frequency) of the space having the shortest run length in the normal area. Therefore, when the appearance frequency of the space having the shortest run length is smaller than the reference frequency by a predetermined ratio, the recording area from which the data pattern including this space is read may be determined as the defective area. . In addition, the appearance frequency of a mark or space other than the mark or space having the shortest run length in the defect area is higher than the appearance frequency (that is, the reference frequency) of a mark or space other than the mark or space having the shortest run length in the normal area. Can be bigger. Therefore, when the appearance frequency of a mark or space other than the mark or space having the shortest run length is larger than the reference frequency by a predetermined rate, the recording area from which the data pattern including the mark or space is read is a defective area. You may comprise so that it may determine.

In particular, in such a defective area, due to the decrease in the appearance frequency of the space having the shortest run length, the fluctuation in the appearance frequency of the space having the relatively long run length or the longest is the largest. Therefore, it is preferable to detect the defect area based on the appearance frequency of the space having a relatively long run length. Here, with reference to FIG. 7, the appearance frequency of a space having a relatively long or long run length will be described. FIG. 7 is a graph showing the appearance frequency of the space in each of the normal area and the defective area. In FIG. 7, an example in which a Blu-ray Disc is used as the optical disc 100 will be described.

As shown in FIG. 7, the appearance frequency of the longest run-length space (that is, the run-length 9T space) in the defect area to which fingerprints or the like are attached is higher than the appearance frequency of the longest run-length space in the normal area. Can be bigger. This occurs for the following reasons. For example, a mark that should originally be recorded as a 2T mark with a run length is recorded as a 1T mark with a run length of 1T. If the spaces are connected, the run length may appear as a 9T space.

Therefore, when the appearance frequency of the space having the longest run length in the defective area is larger than the reference frequency by a predetermined ratio, the recording area from which the data pattern including this space is read is determined to be the defective area. May be. In this way, the defect area is detected based on the longest run length whose run length varies depending on the appearance frequency of the mark with the shortest run length that is susceptible to fingerprints, etc. In addition, it is possible to detect a defective area easily.

In addition, as shown in FIG. 7, in the defect area, the run length (specifically, 1T or 10T or more) other than the run length (specifically, 2T to 9T) determined by the standard increases. is doing. For example, a run-length space of 10T or more may appear when a run-length 2T mark is recorded as a 1-T mark with a run length that is connected to another space. Accordingly, the defect area may be detected based on the appearance frequency of a run-length space other than the run-length determined by the standard. In this case, when the appearance frequency of a run length space other than the run length defined in the standard is equal to or higher than a predetermined amount, it is determined that the recording area from which the data pattern including this space is read is a defective area. You may comprise.

Furthermore, the same can be said for the appearance frequency of run-length marks other than the run-length specified in the standard, as well as the appearance frequency of run-length spaces other than the run-length specified in the standard. Here, the appearance frequency of run-length marks other than the run-length defined by the standard will be described with reference to FIG. FIG. 8 is a graph showing the appearance frequency of the mark in each of the normal area and the defective area. In FIG. 8, an example in which a Blu-ray Disc is used as the optical disc 100 will be described.

As shown in FIG. 8, in the defect area, marks of run lengths (specifically, 1T) other than the run lengths (specifically, 2T to 9T) defined in the standard are increased. Therefore, the defect area may be detected based on the appearance frequency of a run length mark other than the run length defined in the standard. In this case, when the appearance frequency of a run-length mark other than the run-length defined in the standard is a predetermined amount or more, it is determined that the recording area from which the data pattern including the mark is read is a defective area. You may comprise.

Also, Blu-ray Disc, which is a specific example of the optical disc 100, employs a data pattern including a run length 9T mark and a run length 9T space alternately as a sync pattern (synchronization pattern). The defect area may be detected based on the appearance frequency of each of the mark having a run length of 9T and the space having a run length of 9T in the sync pattern. This example will be described with reference to FIG. FIG. 9 is a graph showing the difference in appearance frequency between the mark having a run length of 9T and the space having a run length of 9T in the sync pattern.

As shown in FIG. 9, in the normal region, the appearance frequency of the mark having the run length of 9T and the space having the run length of 9T in the sync pattern are substantially the same. That is, the frequency difference (= appearance frequency of a mark with a run length of 9T−appearance frequency of a space with a run length of 9T) is substantially zero. On the other hand, in the defect area, the appearance frequency of the mark having a run length of 9T and the space having a run length of 9T in the sync pattern are different. Specifically, for example, if a mark with a run length of 2T is recorded as a mark with a run length of 1T, and a space with a run length of 1T is connected to another space, the run length is The appearance frequency of the 9T space may increase with respect to the appearance frequency of the 9T mark. Also, for example, when a run length 2T mark is recorded as a run length 1T mark and a run length 9T space is connected to another space, the run length 9T The appearance frequency of the space may be reduced with respect to the appearance frequency of the mark having a run length of 9T.

As described above, when there is a difference between the appearance frequency of the mark having the run length of 9T and the appearance frequency of the space having the run length of 9T in the sync pattern, the data pattern including the sync pattern is read. It may be determined that the region is a defective region. That is, if the frequency difference (= appearance frequency of a mark with a run length of 9T−appearance frequency of a space with a run length of 9T) is not 0 (more preferably, greatly different from 0), the sync pattern is included. It may be determined that the recording area from which the data pattern has been read is a defective area. Thereby, a defect area | region can be detected suitably.

(3) Modified Example Next, with reference to FIG. 10, a modified example of the reproducing apparatus 1 according to the present embodiment will be described. FIG. 10 is a block diagram conceptually showing the structure of the reproducing apparatus 2 according to the modification. In addition, about the structure same as the reproducing | regenerating apparatus 1 mentioned above, the same referential mark is attached | subjected and the detailed description is abbreviate | omitted.

As shown in FIG. 10, the playback apparatus 2 according to the modified example is similar to the playback apparatus 1 described above, and includes a spindle motor 10, a pickup (PU: Pick Up) 11, an HPF (High Pass Filter) 12, and A A / D converter 13, a pre-equalizer 14, a binarization circuit 16, a decoding circuit 17, a T frequency detection circuit 21, and a defect area detection circuit 22 are provided.

In particular, the reproduction apparatus 2 according to the modification includes a limit equalizer 15 between the pre-equalizer 14 and the binarization circuit 16. Limit equalizer 15 constitutes one specific example of the "amplitude limiting filtering device" of the present invention, subjected to a high frequency emphasis processing to the read sample value series RS _C without increasing the intersymbol interference, resulting the high-frequency enhanced read sample value sequence RS _H obtained, and outputs it to the binary circuit 16. The operation itself of the limit equalizer 15 is the same as the operation of the conventional limit equalizer. For details, see Japanese Patent No. 3459563.

In particular, the limit equalizer 15 is configured to be able to arbitrarily switch on and off. When the limit equalizer 15 is on the to the binarizing circuit 16, while the high-frequency emphasized read sample value series RS _H is outputted, when the limit equalizer 15 is turned off, the binarizing circuit to 16, read sample value series RS _C, which is the output of the pre-equalizer 14 is outputted.

Furthermore, in the modification, the T frequency detection circuit 21 detects each of the appearance frequency when the limit equalizer 15 is on and the appearance frequency when the limit equalizer 15 is off.

Here, when the limit equalizer 15 is on, the following processing is performed. First, the amplitude level of the read signal R _RF is limited by a predetermined amplitude limit value. Specifically, the signal level of the read signal R _RF whose amplitude level is larger than the upper limit or lower limit of the amplitude limit value is limited to the upper limit or lower limit of the amplitude limit value. On the other hand, the amplitude level of the signal component whose amplitude level is below the upper limit and above the lower limit of the amplitude limit value in the read signal R _RF is not limited. By performing the amplitude limiting process in this manner, the amplitude limiting signal R _LIM is generated. A high-frequency emphasis filtering process is performed on the amplitude limit signal R _LIM . Here, the high-frequency emphasis filtering process is a process of increasing the signal level in the vicinity of the signal component corresponding to the mark or space having the shortest run length in the amplitude limit signal R _LIM , for example. As a result, high-frequency emphasized read sample value series RS _H is generated.

Thus, since the signal component of the mark or space with the shortest run length is emphasized, the signal component corresponding to the mark with the shortest run length does not intersect the binarized slice level (on the right side of FIG. 5). Even if the data pattern is recorded in (see the figure), the data pattern can be reproduced so that this signal component intersects the binarized slice level (see the figure on the left side of FIG. 5). That is, the signal component of the mark or space having the shortest run length in the so-called normal region can be output from the limit equalizer 15.

Therefore, in the modification, the defective area detection circuit 22 uses the appearance frequency detected in a state where the limit equalizer 15 is turned on as the reference frequency described above. That is, the defect area detection circuit 22 has an appearance frequency detected when the limit equalizer 15 is off larger or smaller than an appearance frequency detected when the limit equalizer 15 is on, or a predetermined value. A defective area is detected by determining whether the ratio is larger or smaller by a predetermined ratio.

Thereby, also in the reproducing apparatus 2 according to the modified example, various effects that can be enjoyed by the reproducing apparatus 1 described above can be suitably enjoyed. In addition, since it is not necessary to previously store a table or the like indicating the reference frequency described above, the defect region based on the appearance frequency described above can be applied to the optical disc 100 for which the reference frequency is not set or the unknown optical disc 100. A detection operation can be performed.

The present invention is not limited to the above-described embodiments, 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 a reproducing apparatus and method with such changes. In addition, computer programs are also included in the technical scope of the present invention.

Claims

A signal component of a plurality of types of marks included in a read signal obtained by reading a data pattern from a recording medium and having different run lengths, and a signal component of a plurality of types of spaces included in the read signal and having different run lengths. Detecting means for detecting an appearance frequency of at least one of the signal components;
Determination means for determining whether a recording area on the recording medium from which the read signal is read is a defective area based on a change amount of the appearance frequency of the at least one signal component. Playback device.
The detecting means detects the frequency of appearance of the signal component of the mark having the shortest run length;
The determination means determines whether a recording area on the recording medium from which the read signal is read is a defective area based on a change amount of the appearance frequency of the signal component of the mark having the shortest run length. The playback apparatus according to claim 1, wherein:
The detection means detects the frequency of appearance of the signal component of the space having the shortest run length,
The determination means determines whether the recording area on the recording medium from which the read signal is read is a defective area, based on a change amount of the appearance frequency of the signal component of the space having the shortest run length. The playback apparatus according to claim 1, wherein:
The determination means determines that the recording area on the recording medium from which the read signal has been read is a defective area when the appearance frequency is smaller than a predetermined ratio with respect to a predetermined reference frequency. The playback apparatus according to claim 2 or claim 3.
The detection means detects the appearance frequency of a signal component in a space having a relatively long run length included in the read signal,
The determination means determines whether the recording area on the recording medium from which the read signal is read is a defective area based on a change amount of the appearance frequency of a signal component of a space having a relatively long run length. The playback apparatus according to claim 1, wherein
The detection means detects the frequency of appearance of the signal component of the space having the longest run length included in the read signal,
The determination means determines whether or not the recording area on the recording medium from which the read signal is read is a defective area, based on a change amount of the appearance frequency of the signal component of the space having the longest run length. The playback apparatus according to claim 1, wherein:
The determination means determines that the recording area on the recording medium from which the read signal is read is a defective area when the appearance frequency is greater than a predetermined ratio with respect to a predetermined reference frequency. The playback apparatus according to claim 5 or 6.
The detection means detects an appearance frequency of at least one signal component of a violation run-length mark and a violation run-length space different from a run length included in the read signal and predetermined by a standard,
The determination means determines that a recording area on the recording medium from which the read signal is read is defective based on a change amount of the appearance frequency of at least one signal component of the violation run-length mark and the violation run-length space. 2. The playback apparatus according to claim 1, wherein it is determined whether or not it is an area.
The determination means determines that the recording area on the recording medium from which the read signal is read is a defective area when the appearance frequency is greater than a predetermined ratio with respect to a predetermined reference frequency. The playback device according to claim 8.
On the recording medium, there is recorded a sync pattern that includes each of the predetermined run-length mark and the predetermined run-length space substantially equally,
The detection means detects the frequency of appearance of the signal component of the mark of the predetermined run length included in the read signal and the signal component of the space of the predetermined run length included in the read signal,
The determination means is configured on the recording medium from which the read signal is read based on a change amount of the appearance frequency of the signal component of the mark of the predetermined run length with respect to the appearance frequency of the signal component of the space of the predetermined run length. 2. The reproducing apparatus according to claim 1, wherein it is determined whether or not the recording area is a defective area.
An amplitude limit that acquires an amplitude limit signal by limiting the amplitude level of the read signal with a predetermined amplitude limit value, and acquires an equalization correction signal by performing a high-frequency emphasis filtering process on the amplitude limit signal Further comprising filtering means,
The determination unit is configured to determine the read signal based on a change amount of an appearance frequency of at least one signal component included in the read signal with respect to an appearance frequency of the at least one signal component included in the equalization correction signal. 2. The reproducing apparatus according to claim 1, wherein it is determined whether or not the recording area on the recording medium from which the data has been read is a defective area.
Among the signal components of a plurality of types of marks having different run lengths included in a read signal obtained by reading a data pattern from a recording medium, and the signal components of a plurality of types of spaces having different run lengths included in the read signal A detection step of detecting an appearance frequency of at least one signal component;
A determination step of determining whether a recording area on the recording medium from which the read signal is read is a defective area, based on a change amount of the appearance frequency of the at least one signal component. How to play.
Among the signal components of a plurality of types of marks having different run lengths included in a read signal obtained by reading a data pattern from a recording medium, and the signal components of a plurality of types of spaces having different run lengths included in the read signal Based on a detecting means for detecting an appearance frequency of at least one signal component, and an amount of change between the appearance frequency of the at least one signal component and a reference frequency corresponding to the at least one signal component, the read signal is A computer program for playback control that controls a computer provided in a playback device including a determination unit that determines whether or not a read recording area on the recording medium is a defective area,
A computer program for reproduction control, which causes the computer to function as the detection unit and the determination unit.