JP2007172689A - Optical information recording medium, information reproducing method, and information reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely detect a prescribed shortest pattern and a synchronization signal by carrying out reproduction neglecting waveform distortion even if a longest pattern contains high-frequency waveform distortion. <P>SOLUTION: An equalizer 96 includes a gain emphasis part 110 which increases a gain in a specific frequency band, and a gain upper limit setting part 112 which determines an upper limit value of the gain according to a distortion amount contained in a reproduced waveform 104 of the longest pattern 30b recorded in a test recording area 42 in the reproduction period of the test recording area. Then, expressing the maximum amplitude of a reproduced waveform of an optical disk by A, the amplitude of the distortion component contained in the reproduced waveform of the longest pattern by D, and a current gain of the equalizer 96 by g, (g×D)/A is calculated and adopted as the distortion amount. A gain with a distortion amount of 0.1 is stored in a register 114 as the upper limit value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical information recording medium having a pre-groove and a recording layer and capable of recording and / or reproducing information by irradiating the recording layer with laser light, and reproducing information from the optical information recording medium. The present invention relates to an information reproducing method and an information reproducing apparatus.

  Conventionally, when recording information on an optical information recording medium (hereinafter referred to as an optical disk) capable of recording and / or reproducing information by irradiating the recording layer with laser light, the intensity of the laser light is optimized, A technique has been proposed in which a recording / reproducing apparatus is incorporated with a system for changing a recording strategy for each optical disc of a different manufacturer (for example, Patent Document 1). This is due to the fact that the optical information recording medium cannot be recorded the same even under the same recording conditions due to the recording device, recording material, environmental temperature, wavelength variation of the laser light source, and the like.

  On the other hand, for the reproduction of information from the optical disc, an equalization gain at the time of reproduction is defined. Conventionally, for example, Patent Document 2 describes a method for recording information on optimum equalization gain based on information obtained in advance. The method for obtaining the optimum equalization gain information includes a gain value that maximizes the jitter margin. The method used is used. Patent Document 3 describes a method of amplifying high frequency components in accordance with the focus state.

  However, as described above, the equalization gain at the time of reproduction is defined, but the jitter greatly changes depending on the equalization gain, and stable reproduction may not be possible within the standard equalization gain range.

  Therefore, conventionally, when reproducing information from an optical disk to obtain a reproduction signal and binarizing the reproduction signal by waveform equalization, the shortest mark length of the reproduction signal binarized by waveform equalization and the shortest mark Information is reproduced by setting the waveform equivalent gain so that the difference from the theoretical value of the length becomes almost zero (see, for example, Patent Document 4).

Japanese Unexamined Patent Publication No. Hei 8-249626 Japanese Patent Laid-Open No. 9-7178 Japanese Patent Publication No. 7-52510 JP 2000-30259 A

  By the way, in the recordable optical disc as described above, the reproduction waveform may be distorted depending on the recording material and the recording conditions (laser power, laser emission pattern, recording apparatus, recording speed, etc.). Occurs in the waveform. Such waveform distortion causes erroneous detection of the reproduction signal, and causes an error. In general, data is recorded in units of blocks, and the synchronization signal (Sync signal) often includes a long mark signal. When erroneous detection of a long mark occurs due to waveform distortion, all the blocks are unrecognized at the time of reproduction, which causes a problem in data decoding.

  In the optical disk apparatus, the frequency characteristic of the optical pickup is generally called MTF (Modulation Transfer Fuction). The gain characteristic of this MTF decreases monotonously (high-frequency attenuation). Therefore, in general, in an optical disc apparatus, the MTF is corrected using an equalizer using a transversal filter.

  Normally, the high frequency is emphasized by an equalizer to improve the S / N of the signal of the shortest pattern recording frequency, but when a pattern other than the shortest pattern, for example, a long pattern such as the longest pattern, has high-frequency waveform distortion. The distortion will be emphasized.

  In recent years, a technique (partial response method) has been introduced such as multi-value determination for decoding high-density recording when reproducing reproduced data. In this method, waveform distortion is more important than conventional slice detection. There is a problem that false detection is likely to occur.

  The present invention has been made in consideration of such a problem, and even if there is a high-frequency waveform distortion in a pattern other than the shortest pattern, for example, a long pattern such as the longest pattern, reproduction is performed so as to ignore the waveform distortion. Provided is an optical information recording medium, an information reproducing method, and an information reproducing apparatus capable of reliably detecting a prescribed shortest pattern and synchronization signal and improving the accuracy of reproduction and the reliability of data decoding. The purpose is to do.

  An optical information recording medium according to a first aspect of the present invention is an optical information recording medium capable of recording and / or reproducing information by irradiating the recording layer with laser light, wherein the recording layer is information on which user information is recorded. It has a recording area and at least a recording test area used for adjusting the output of the laser beam, and at least the longest recording pattern is recorded in the recording test area.

  Thereby, the information recorded in the recording test area is used to determine the level of enhancement processing for the reproduction waveform of the optical information recording medium according to the amount of distortion included in the reproduction waveform of the longest recording pattern. can do.

  The information reproducing method according to the second aspect of the present invention is the information reproducing method for reproducing information on an optical information recording medium capable of recording and / or reproducing information by irradiating the recording layer with laser light. The optical information recording medium has an information recording area where user information is recorded and a recording test area used to adjust at least the output of the laser beam, and the longest recorded in the recording test area Information is reproduced by determining the level of enhancement processing for the reproduction waveform of the optical information recording medium in accordance with the amount of distortion included in the reproduction waveform of the recording pattern.

  According to a third aspect of the present invention, there is provided an information reproducing apparatus for reproducing information from an optical information recording medium capable of recording and / or reproducing information by irradiating a recording layer with laser light. The optical information recording medium has an information recording area where user information is recorded and a recording test area used to adjust at least the output of the laser beam, and the longest recorded in the recording test area Means for reproducing a recording pattern; means for detecting a distortion amount included in the reproduction waveform of the longest recording pattern; and a level of enhancement processing on the reproduction waveform of the optical information recording medium according to the detected distortion amount And means for determining.

  In the first to third aspects of the present invention, even if a pattern other than the shortest pattern, for example, a long pattern such as the longest pattern, has a high-frequency waveform distortion, the waveform distortion can be reproduced so as to be ignored. The shortest pattern and the synchronization signal can be reliably detected, and the reproduction accuracy and the reliability of data decoding can be improved.

  In the first to third aspects of the invention, the enhancement processing is signal processing for increasing a gain of a reproduction waveform included in a specific frequency region of the reproduction waveform, and the level of the enhancement processing is the reproduction processing. It may be a waveform gain.

  The distortion amount is (g × where A is the maximum amplitude of the reproduction waveform of the optical information recording medium, D is the amplitude of the distortion component included in the reproduction waveform of the longest recording pattern, and g is the gain). D) / A, and the enhancement processing may set the gain for the reproduced waveform in the information recording area, with the gain at which the distortion amount is 0.1 as an upper limit value.

  As described above, according to the optical information recording medium, the information reproducing method, and the information reproducing apparatus according to the present invention, even if a pattern other than the shortest pattern, for example, a long pattern such as the longest pattern has high-frequency waveform distortion, The reproduction can be performed so as to ignore the waveform distortion, the specified shortest pattern and the synchronization signal can be reliably detected, and the reproduction accuracy and the reliability of data decoding can be improved.

  Embodiments in which the optical information recording medium, the information reproducing method and the information reproducing apparatus according to the present invention are applied to an optical information recording medium (optical disc) capable of recording and reproducing information using laser light, for example. Will be described with reference to FIGS.

  As shown in FIG. 1, an optical disk 10 according to the present embodiment includes a substrate 14 having a pregroove 12 formed on one main surface, a reflective layer 16 formed on the substrate 14, and a reflective layer 16 on the reflective layer 16. The information recording layer 18 is formed on the information recording layer 18, the dielectric layer 20 is formed on the information recording layer 18, and the protective layer 22 is formed on the dielectric layer 20.

  The recording is performed on the information recording layer 18 by irradiating, for example, the main surface of the protective layer 22 toward the substrate 14 with the recording laser beam 24w or the reproduction laser beam 24r modulated based on the information to be recorded. The information that should be recorded is recorded as pits. As the recording laser beam 24w and the reproduction laser beam 24r, for example, a laser beam having a wavelength of 350 to 450 nm is used.

  When the pit length is expressed by the clock period T of the modulation signal in EFM modulation or 8/16 modulation, 3T to 11T are used, and a blank is set between the pits. In the example of FIG. 2, a case where pits 32 of 3T (shortest pattern 30a) to 4T, 5T... 11T (longest pattern 30b) are respectively set with blanks 34 is recorded.

  In particular, the information recording layer 18 of the optical disc 10 according to the present embodiment has an information recording area 40 where user information is recorded, and a recording test area 42 used to adjust at least the output of the laser beam 24. In this recording test area 42, at least the longest pattern 30b (see FIG. 2) is recorded. The recording test area 42 is originally used for adjusting the output of the laser beam 24 as described above. In the present embodiment, the waveform distortion that appears during reproduction of the longest pattern 30b is detected. This is used to adjust the gain of an equalizer described later. Note that the information recording area 40 is divided into, for example, a plurality of blocks, and a synchronization signal (sync signal) and user information are recorded in each block.

  On the other hand, as shown in FIG. 4, the recording / reproducing apparatus 50 according to the present embodiment has a spindle motor 52 on which the optical disk 10 is mounted, and the optical disk 10 is inserted into a CLV (constant linear velocity) system or CAV (angular velocity). A rotation drive control unit 54 that rotates in a constant manner, a pickup 56 that is disposed to face one surface of the optical disk 10 (an end surface of the protective layer 22), and a pickup that moves at least the pickup 56 in the radial direction of the optical disk 10. A moving mechanism 58 and a control unit 60 for controlling the rotational drive control unit 54, the pickup 56, the pickup moving mechanism 58, and the like are included.

  The rotation drive control unit 54 controls the spindle motor 52 to rotate at a constant linear velocity or a constant angular velocity at a set recording speed magnification in accordance with a command from the control unit 60. For example, the control at a constant linear velocity is performed by detecting a pre-group wobble component in the reproduction signal reproduced by the pickup 56 and adjusting the frequency of the wobble component to a specified frequency. Is PLL controlled.

  The pickup moving mechanism 58 controls the focus and tracking of the laser beam 24 emitted from the pickup 56 according to a command from the control unit 60, and further feed-controls the pickup 56 in the radial direction of the optical disk 10.

  As shown in FIG. 5, the focus control and tracking control of the recording laser beam 24w and the reproduction laser beam 24r emitted from the pickup 56 are performed as shown in FIG. Is detected by the detection circuit 62. That is, the detected pre-group signal component Srp is supplied to the servo control signal generation circuit 64 and calculated to generate the focus error signal Sfe and the tracking error signal Ste, which cancel the focus error signal Sfe and the tracking error signal Ste. Thus, the focal position of the objective lens (not shown) of the pickup 56 and the radial position of the pickup 56 are controlled.

  Information to be recorded on the optical disk 10 is modulated as follows. That is, when the input signal Si is a digital signal, that is, input data Sdi, it is directly input to the data signal forming circuit 70 at a speed corresponding to the recording speed magnification. When the input signal Si is an analog signal Sai, it is converted into a digital signal (input data) Sdi via the A / D converter 72 and input to the data signal forming circuit 70 at a speed corresponding to the recording speed magnification.

  The data signal forming circuit 70 interleaves the input data Sdi, gives an error check code, and gives TOC information Di and subcode information Ds generated by the TOC generation circuit 74 and the subcode generation circuit 76. Then, predetermined modulation (EFM modulation or 8/16 modulation) is performed to form a series of serial data at a transfer rate corresponding to the recording format and recording speed magnification of the optical disc 10, and output as a recording signal Dw.

  This recording signal Dw is modulated by a recording strategy selected by the recording signal correction circuit 80 (irradiation control means) via the drive interface 78 in accordance with the type of disk used (type of dye material), linear velocity, recording velocity magnification, and the like. Then, it is input to the laser generation circuit 82.

  The laser generation circuit 82 drives the semiconductor laser of the pickup 56 in accordance with the recording signal Dw to irradiate the information recording layer 18 (see FIG. 1) of the optical disc 10 with the recording laser beam 24w, and the pit 32 (see FIG. 2). Is recorded. At this time, before recording user information in the information recording area 40, various recording patterns are recorded in the recording test area 42 in advance to set the best laser power. Here, at least the shortest pattern 30a and the longest pattern 30b are recorded.

  The laser power is set to a value corresponding to the recording speed magnification and the linear velocity as necessary (that is, the laser power to be irradiated to form a predetermined pit length under a predetermined irradiation time). The ALPC (Automatic Laser Power Control) circuit 84 controls the power to be set. As a result, data is recorded on the optical disc 10 at a prescribed recording format, transfer rate, and linear velocity.

  When information is reproduced from the optical disk 10 on which information is recorded as described above, reproduction is performed by irradiating the reproducing laser beam 24r (power smaller than that of the recording laser beam 24w) from the pickup 56. As shown in FIG. 7, the data (reproduced signal Sr) reproduced by the pickup 56 is demodulated by the signal reproduction processing circuit 90 and is directly converted into the digital signal Sdr or converted to the analog signal Sar by the D / A converter 92. Is output.

  The recording / reproducing apparatus 50 according to this embodiment includes the following circuits in the signal reproduction processing circuit 90 as shown in FIG.

  That is, the signal reproduction processing circuit 90 includes a low-pass filter (LPF) 94 that removes a high-frequency noise component included in the reproduction signal Sr from the pickup 56, and a specific frequency band (shortest pattern 30a) among the output signal Sr1 from the LPF. The equalizer 96 that emphasizes the amplitude of the reproduction signal frequency band and shapes the waveform of the reproduction signal, and a high-pass filter (HPF) that removes the direct current component from the signal Sr2 from the equalizer 96 to obtain the RF signal Sr3. 98, a slice level controller 100 that binarizes the RF signal Sr3 from the HPF 98 at a predetermined slice level for binarization, and a decoder that decodes and demodulates the binarized signal Sr4 from the slice level controller 100 102.

  Then, errors and jitter are detected based on an output signal (digital signal Sdr or analog signal Sar) from the decoder 102, and error correction is performed to reproduce the recording signal Dw.

  Incidentally, as shown in FIGS. 8A and 8B, a high-frequency distortion component 106 may occur in the reproduced waveform 104 of the longest pattern 30b. When the frequency of the distortion component 106 is included in the above-described specific frequency band, the amplitude D is emphasized by the equalizer 96, and it may be handled as if it is the reproduced waveform 108 of the shortest pattern 30a. In general, recorded information is recorded together with a synchronization signal in units of blocks, and this synchronization signal often includes the longest pattern 30b. When the longest pattern 30b included in this synchronization signal is reproduced, the longest pattern 30b is originally supposed to be the longest pattern 30b, but if it is recognized as a pattern at an intermediate level with the shortest pattern 30a, the synchronization signal cannot be detected. The recorded information of the entire block cannot be reproduced.

  Therefore, in the present embodiment, the equalizer 96 is configured to have the following functions. That is, as described above, the equalizer 96 has the function of increasing the gain in the specific frequency band (the band including the frequency of the reproduction signal of the shortest pattern 30a) (gain emphasis unit 110) and the reproduction period of the recording test area 42. A function (gain upper limit setting unit 112) for determining an upper limit value of the gain according to the distortion amount included in the reproduction waveform 104 of the longest pattern 30b recorded in the recording test area 42; These functions may be configured by hardware, may be configured by software, or may be configured by a mixture of hardware and software.

  Here, the function of the equalizer 96 will be described. The gain upper limit setting unit 112 sets the upper limit value of the gain during the input period of the upper limit setting command St from the control unit 60. The upper limit setting command St is output as follows. First, the control unit 60 starts reproduction of the recording test area 42 based on the reproduction start signal Srs, and sets the upper limit to the equalizer 96 only during the period during which the longest pattern 30b recorded in the recording test area 42 is reproduced. A setting command St is output.

  The gain upper limit setting unit 112 increases the gain by a predetermined amount every time the upper limit setting command St is input from the control unit 60, and performs the following calculation. That is, as shown in FIG. 8A, when the maximum amplitude of the reproduction waveform of the optical disc 10 is A, the amplitude of the distortion component 106 included in the reproduction waveform 104 of the longest pattern 30b is D, and the current gain of the equalizer 96 is g. Calculate (g × D) / A, and use this as the amount of distortion.

  Then, for example, the gain at which the distortion amount is 0.1 is registered in the register 114 as an upper limit value. Preferably, if D / A is a value smaller than 0.01, the gain at which distortion amount: (g × D) / A is 0.01 is set as the upper limit value, and D / A is larger than 0.01. If it is a value, the gain at which the strain amount: (g × D) / A is 0.1 is set as the upper limit value.

  When the gain of the equalizer 96 is determined by the filter coefficient, the filter coefficient may be set so that the gain gradually increases.

  When the upper limit value of the gain of the equalizer 96 is determined, the gain upper limit setting unit 112 outputs a signal Se indicating setting completion to the control unit 60. The control unit 60 performs control so that a block to be reproduced is reproduced by the pickup 56 when the signal Se indicating the completion of setting is received.

  The gain emphasizing unit 110 of the equalizer 96 increases the gain of a signal in a specific frequency band among the signals Sr1 sent one after another, with the value registered in the register 114 as an upper limit value. At this time, when the longest pattern 30b included in the synchronization signal recorded together with the block is reproduced, even if the distortion component 106 is included in the reproduction waveform 104, the distortion component is at most the reproduced signal. The maximum amplitude A is only 0.01 or less or 0.1 or less. For this reason, in the binarization by the slice level controller 100 at the subsequent stage, the distortion component 106 is substantially ignored, and the longest pattern 30b is not erroneously detected as the shortest pattern 30a and the intermediate level pattern. The longest pattern 30b is detected, and the information recorded together with the synchronization signal is surely reproduced.

  That is, in the recording / reproducing apparatus 50 and the recording / reproducing method according to the present embodiment, as shown in FIG. 9, first, in step S1, various recording patterns are recorded in advance in the recording test area 42 to obtain the best laser power. Set. Conventionally, a random recording pattern is recorded in order to derive the optimum recording power. In the present embodiment, the longest recording pattern (the longest pattern 30b) is further used under the optimum recording condition (optimal recording power). Is recorded.

  Thereafter, in step S2, the longest pattern 30b in the recording test area 42 is reproduced.

  Thereafter, in step S3, a waveform equivalent gain upper limit value is determined from the distortion amount of the reproduction signal of the longest pattern 30b.

  In step S4, conventional waveform equalization is performed within a range not exceeding the determined gain upper limit value.

  As described above, in the optical disc 10, the recording / reproducing apparatus 50, and the recording / reproducing method according to the present embodiment, even when a high-frequency distortion component 106 is present in a pattern other than the shortest pattern 30a, for example, a long pattern such as the longest pattern 30b. The distortion component 106 can be reproduced so as to be ignored, the specified shortest pattern 30a and the synchronization signal can be reliably detected, and the reproduction accuracy and data decoding reliability can be improved.

  The optical information recording medium, information reproducing method, and information reproducing apparatus according to the present invention are not limited to the above-described embodiments, and can of course have various configurations without departing from the gist of the present invention. .

It is sectional drawing which abbreviate | omits and shows a part of structure of the optical disk based on this Embodiment. It is explanatory drawing which shows an example of the recording signal recorded with the recording / reproducing apparatus which concerns on this Embodiment, and the pit shape corresponding to it. It is explanatory drawing which shows the data form recorded on 1 track | truck of the optical disk based on this Embodiment. It is a block diagram which shows schematically the recording / reproducing apparatus which concerns on this Embodiment. It is a block diagram which shows roughly the servo control system of the recording / reproducing apparatus which concerns on this Embodiment. It is a block diagram which shows roughly the information recording system of the recording / reproducing apparatus concerning this Embodiment. It is a block diagram which shows roughly the information reproduction system of the recording / reproducing apparatus which concerns on this Embodiment. FIG. 8A is a diagram showing the reproduction waveforms of the shortest pattern and the longest pattern, and FIG. 8B is an explanatory diagram showing the arrangement of the shortest pattern and the longest pattern. It is a flowchart which shows the processing operation of the recording / reproducing apparatus and recording / reproducing method which concern on this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical disk 12 ... Pre-groove 14 ... Substrate 18 ... Information recording layer 24r ... Reproducing laser beam 24w ... Recording laser beam 30a ... Shortest pattern 30b ... Longest pattern 32 ... Pit 40 ... Information recording area 42 ... Recording test area 50 ... Recording / reproducing apparatus 56... Pickup 60... Control unit 96 .. equalizer 110... Gain emphasis unit 112.

Claims (10)

In an optical information recording medium capable of recording and / or reproducing information by irradiating a recording layer with laser light,
The recording layer has an information recording area in which user information is recorded, and a recording test area used to adjust at least the output of the laser beam,
An optical information recording medium, wherein at least the longest recording pattern is recorded in the recording test area. The optical information recording medium according to claim 1,
The information recorded in the recording test area is used to determine the level of enhancement processing for the reproduction waveform of the optical information recording medium according to the amount of distortion included in the reproduction waveform of the longest recording pattern. An optical information recording medium characterized by the above. The optical information recording medium according to claim 2,
The enhancement processing is signal processing for increasing the gain of a reproduction waveform included in a specific frequency region of the reproduction waveform,
The optical information recording medium, wherein the level of the enhancement processing is a gain of the reproduction waveform. The optical information recording medium according to claim 3.
The distortion amount is (g × D) where A is the maximum amplitude of the reproduction waveform of the optical information recording medium, D is the amplitude of the distortion component included in the reproduction waveform of the longest recording pattern, and g is the gain. / A,
The optical information recording medium according to claim 1, wherein the enhancement processing sets a gain for a reproduction waveform in the information recording area, with an upper limit value being a gain at which the distortion amount is 0.1. In an information reproducing method for reproducing information on an optical information recording medium capable of recording and / or reproducing information by irradiating a recording layer with laser light,
The optical information recording medium has an information recording area in which user information is recorded, and a recording test area used to adjust at least the output of the laser beam,
Information is reproduced by determining a level of emphasis processing on the reproduction waveform of the optical information recording medium in accordance with the amount of distortion included in the reproduction waveform of the longest recording pattern recorded in the recording test area. Information reproduction method. The information reproducing method according to claim 5, wherein
The enhancement processing is signal processing for increasing the gain of a reproduction waveform included in a specific frequency region of the reproduction waveform of the optical information recording medium,
The information reproduction method characterized in that the level of the enhancement processing is a gain of the reproduction waveform. The information reproduction method according to claim 6,
The distortion amount is (g × D) where A is the maximum amplitude of the reproduction waveform of the optical information recording medium, D is the amplitude of the distortion component included in the reproduction waveform of the longest recording pattern, and g is the gain. / A,
In the enhancement process, the gain for the reproduction waveform in the information recording area is set with a gain at which the distortion amount is 0.1 as an upper limit value. In an information reproducing apparatus for reproducing information on an optical information recording medium capable of recording and / or reproducing information by irradiating a recording layer with laser light,
The optical information recording medium has an information recording area in which user information is recorded, and a recording test area used to adjust at least the output of the laser beam,
Means for reproducing the longest recording pattern recorded in the recording test area;
Means for detecting the amount of distortion included in the reproduced waveform of the longest recording pattern;
Means for determining a level of enhancement processing for the reproduction waveform of the optical information recording medium according to the detected distortion amount. The information reproducing apparatus according to claim 8, wherein
The enhancement processing is signal processing for increasing the gain of a reproduction waveform included in a specific frequency region of the reproduction waveform of the optical information recording medium,
The information reproducing apparatus characterized in that the level of the enhancement processing is a gain of the reproduced waveform. The information reproducing apparatus according to claim 9, wherein
The distortion amount is (g × D) where A is the maximum amplitude of the reproduction waveform of the optical information recording medium, D is the amplitude of the distortion component included in the reproduction waveform of the longest recording pattern, and g is the gain. / A,
The information reproducing apparatus is characterized in that the enhancement processing sets a gain for a reproduction waveform in the information recording area, with an upper limit value being a gain at which the distortion amount is 0.1.

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