JP3910787B2 - Wobble signal detection device, optical disk device, and information processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wobble signal detection device for detecting a wobble signal included in a pregroove formed on a recordable optical disc, an optical disc device including the wobble signal detection device, and an information processing device.
[0002]
[Prior art]
In general, in an additionally recordable or rewritable optical disk, a tracking groove is wobbled and incidental information such as an address is recorded as a wobble signal. That is, a carrier wave having a predetermined frequency (for example, 22.05 kHz) is modulated by additional information such as an address, and a tracking groove is wobbled based on the modulated additional information.
[0003]
In an optical disk apparatus that records, reproduces, or erases information on this type of optical disk, when recording information, a wobble signal included in the optical disk, for example, ATIP as time information indicating an absolute address on the optical disk It is very important to accurately detect the signal (Absolute Time In Pre-groove) in order to accurately perform positioning for recording information and to synchronize with the rotation speed of the optical disk for recording information. It is.
[0004]
That is, in the optical disk apparatus, if the error rate of ATIP signal detection increases during information recording, the synchronization may be lost and a recording error may occur. In particular, in write-once (write-once) CD-R media, if a recording error occurs, the recorded optical disc becomes useless and cannot be reused, so accurate ATIP signal detection is very difficult. is important.
[0005]
When detecting a wobble signal (accompanying information) such as an ATIP signal from an optical disc, a method of detecting from an output difference between two divided light receiving elements for detecting a track error signal is generally widely used. This is because the wobble signal can be detected by separating a predetermined frequency component from the track error signal.
[0006]
However, because the signal level of the ATIP signal formed by meandering the pregroove is very small, detection may be difficult due to various disturbances. Such a problem appears remarkably particularly in an optical disc that records or reproduces data by the intensity of reflected light, such as a write-once type CD-R media and a rewritable CD-RW media. In detecting the wobble signal, it goes without saying that it is desirable to adjust the optical system so that there is no light imbalance in the two detection systems corresponding to the two-divided light receiving elements. In addition to its limitations, it is difficult to deal with unbalances that occur afterward due to changes over time or warping of media.
[0007]
Therefore, for example, when the case of trying to reproduce information is taken as an example, as shown in Japanese Patent Laid-Open No. 05-128564, when the optical axis is shifted, two detections based on which an ATIP signal is obtained are obtained. As shown in a proposed example in which detection is performed by adjusting the signal amplitudes of the systems to be equal, or as disclosed in Japanese Patent Laid-Open No. 06-290462, the signal amplitudes of the two detection systems are summed of the two detection signals. There is a proposed example of trying to detect accurately by normalizing based on a signal (RF signal).
[0008]
However, when recording information, the write-once optical disc is characterized in that the amplitude changes greatly with time, unlike when the signal appearing in the detection system reproduces information.
[0009]
Therefore, in general, when recording information, as shown in Japanese Patent Laid-Open No. 10-11757, when a space other than the case of forming a mark for recording information is formed. The so-called sample hold (S / H) method is used to sample the output of the light receiving element (generally, light is emitted at a low power for reproduction at this time) to detect the information of the ATIP signal. It is done. At this time, it goes without saying that the above-described ATIP signal detection becomes more difficult as the recording speed for recording information increases.
[0010]
[Problems to be solved by the invention]
However, the proposal as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-11757 has the following drawbacks. In order to record information at a high speed, in order to perform sample and hold, an expensive circuit configuration that operates stably at high speed with high accuracy is required. In addition, when recording information at high speed, there is a tendency to make the emission pattern of the semiconductor laser longer than the recording width, and the time during which light is emitted with the light amount of the reproduction level for reproducing information is further shortened. In the sample and hold method, the carrier noise ratio (C / N ratio) for detecting the ATIP signal is deteriorated, and it becomes more difficult to accurately detect the ATIP signal. In particular, recently, the recording speed tends to increase more and more.
[0011]
In addition to the above-mentioned publication examples, there are various proposal examples regarding the detection of the ATIP signal, but in the end, the reproduction operation using the RF signal and the low-speed specification are targeted, and the current or future high-speed recording is performed. There is no proposal example regarding the detection of the ATIP signal in consideration.
[0012]
Therefore, an object of the present invention is to provide a wobble signal detection apparatus that can accurately detect a wobble signal even when information is written on a recordable optical disk at a high speed.
[0013]
Further, the present invention realizes the above object, and can efficiently remove a noise component unrelated to the wobble signal included in the reproduction signal being recorded, and can detect the wobble signal more accurately. A signal detection device is provided.
[0014]
The present invention also provides a wobble signal detection device that can easily achieve the above object.
[0015]
In addition, the present invention provides a wobble signal detection device that can cope with a case where the writing speed for recording information is changed in order to realize the above object.
[0016]
Furthermore, an object of the present invention is to provide an optical disc apparatus and an information processing apparatus that can perform good recording with few errors such as loss of synchronization by including the wobble signal detection apparatus.
[0017]
[Means for Solving the Problems]
  The invention according to claim 1 is a wobble signal detection device for detecting a wobble signal included in a pregroove formed on a recordable optical disc, and is divided into two in the tangential direction of the pregroove and is separated from the pregroove. A light receiving element that receives each reflected light, and a frequency component of a data pattern to be written on the optical disk by a light source for each signal output from these light receiving elements.For low-pass characteristicsA band limiting circuit for band limiting,SaidEach signal output from the band limiting circuitAmplitude ofA correction circuit that performs waveform equalization processing so as to be equal to each other, and a difference signal detection circuit that takes a difference between the signals output from the correction circuit.
[0018]
Therefore, during the recording operation on the optical disc by emitting the light source according to the data pattern to be written, the signals outputted from the light receiving element having the two-divided configuration are made equal by the correction circuit. Before performing waveform equalization processing, the band limiting circuit limits the frequency to remove the frequency component of the data pattern to be written that is not related to the wobble signal, so that the signal input to the correction circuit is the data pattern to be written. Therefore, even during high-speed recording, the correction circuit can perform waveform equalization processing that is not affected by the noise component generated from the data pattern to be written. By taking the difference between the signals output by the difference signal detection circuit, the wobble signal is accurately detected. That is, a wobble signal can be accurately detected with an easy configuration without using a sample-and-hold method that has a limit on high-speed response.
[0019]
  According to a second aspect of the present invention, in the wobble signal detection device according to the first aspect, the band limiting circuitThe cutoff frequency isThan the frequency component of the data pattern to be writtenLowAnd than the frequency of the wobble signalhighSet to frequencyHas low-pass characteristics.
[0020]
  Therefore, the frequency component of the wobble signal is considerably higher than the frequency component of the data pattern to be written.LowTherefore, in the first aspect of the invention, the band limiting frequency of the band limiting circuit is set to be higher than the frequency component of the data pattern to be written to be removed.LowAnd the frequency of the wobble signal to be detectedhighFor example, a low-pass filter (LPF) satisfying such a frequency condition can be used as the band limiting circuit. In this case, the bandwidth limit frequency is sufficiently higher than the frequency component of the data pattern.LowAnd well above the frequency of the wobble signalhighFrequency, as much as possibleLowThe frequency is more preferable because the frequency component of the data pattern can be removed as much as possible without any trouble in the wobble signal to be detected.
[0021]
According to a third aspect of the present invention, in the wobble signal detection device according to the first or second aspect, the optical disk is a write-once optical disk, the wobble signal is an ATIP (Absolute Time In Pre-groove) signal, and the writing should be performed The data pattern is an EFM (Eight to Fourteen Modulation) signal.
[0022]
Therefore, as a specific application example, an ATIP signal can be accurately detected when high-speed recording is performed on a write-once optical disc using an EFM signal.
[0023]
According to a fourth aspect of the present invention, in the wobble signal detection device according to any one of the first to third aspects, the correction amount of the waveform equalization processing in the correction circuit is track error monitored by a track error signal monitoring means. It is variably set according to the amount of signal deviation.
[0024]
Therefore, one of the factors that change the amplitude of each signal from the light-receiving element divided into two is a track shift in which the position of the optical spot with respect to the optical disc deviates from the center of the track. Such a track error signal is generally used. Even if high-speed recording is performed in a state where a track deviation occurs, two types of recording can be performed by monitoring by an appropriate track error signal monitoring means and variably setting the correction amount of the waveform equalization processing in the correction circuit according to the deviation amount. Since the signals are corrected to be equal, the noise component generated from the data pattern to be written, which is not related to the wobble signal included in the signal obtained during recording, can be efficiently removed, resulting in accurate wobble signal Can be detected.
[0025]
According to a fifth aspect of the present invention, in the wobble signal detection device according to any one of the first to third aspects, the correction amount of the waveform equalization processing in the correction circuit is monitored by a lens position signal monitoring unit. Is variably set according to the amount of deviation of the lens position signal.
[0026]
Therefore, one of the factors that change the amplitude of each signal from the light receiving element divided into two is the lens shift in which the light receiving element is shifted from the center of the objective lens. Even if high-speed recording is performed in a state where a lens shift has occurred, monitoring is performed by a typical lens position signal monitoring means, and the correction amount of the waveform equalization processing in the correction circuit is variably set according to the deviation amount. Therefore, the noise component generated from the data pattern to be written which is not related to the wobble signal included in the signal obtained during recording can be efficiently removed, and as a result, the wobble signal is It can be detected accurately.
[0027]
According to a sixth aspect of the present invention, in the wobble signal detection device according to any one of the first to third aspects, the waveform equalization processing in the correction circuit is a maximum of each signal amplitude output from the band limiting circuit. This is a process of making the value constant.
[0028]
  Therefore, during the recording operation on the optical disc by emitting the light source according to the data pattern to be written, the signals outputted from the light receiving element having the two-divided configuration are made equal by the correction circuit. Compared to the frequency component of the wobble signal to be detected in waveform equalization processinghighSince the frequency component of the data pattern to be written is removed in advance by the band limiting circuit, the maximum value of each signal amplitude is kept constant as a waveform equalization process that is not affected by the frequency component of the data pattern to be written in the correction circuit. In particular, a peak detection circuit, a comparator, or the like may be used, which can be easily realized.
[0029]
According to a seventh aspect of the present invention, in the wobble signal detection device according to any one of the first to third aspects, the waveform equalization processing in the correction circuit is an effective signal amplitude of each signal output from the band limiting circuit. This is a process of making the value constant.
[0030]
  Therefore, during the recording operation on the optical disc by emitting the light source according to the data pattern to be written, the signals outputted from the light receiving element having the two-divided configuration are made equal by the correction circuit. Compared to the frequency component of the wobble signal to be detected in waveform equalization processinghighSince the frequency component of the data pattern to be written is removed in advance by the band limiting circuit, the effective value of each signal amplitude is made constant as a waveform equalization process that is not affected by the frequency component of the data pattern to be written in the correction circuit. This process can be simplified, and specifically, an effective value detection circuit, a comparator, or the like may be used, which can be easily realized.
[0031]
According to an eighth aspect of the present invention, in the wobble signal detection device according to any one of the first to seventh aspects, the band limiting frequency of the band limiting circuit can be variably set according to the writing speed.
[0032]
Therefore, the wobble signal is a signal obtained by FM-modulating a carrier wave of a specific frequency, and this carrier wave changes as the writing speed for recording information changes. By variably setting the band limiting frequency, it is possible to limit the band suitable for the writing speed, and the wobble signal can be accurately detected regardless of the writing speed. In other words, it can cope with not only high-speed recording but also low-speed recording.
[0033]
An optical disc apparatus according to a ninth aspect of the invention is a rotary drive means for rotationally driving a recordable optical disc on which a pre-groove having a wobble signal is formed, a light source, and light from the light source is collected on the pre-groove of the optical disc. An optical pickup having an objective lens for irradiating light and movable in the radial direction of the optical disc, light source drive control means for emitting the light source according to a data pattern to be written at the time of recording, and 2 in the tangential direction of the pregroove The wobble signal detection device according to claim 1, further comprising: a light receiving element in the optical pickup that is divided and receives light reflected from the pregroove.
[0034]
Therefore, since the wobble signal detection device according to any one of claims 1 to 8 can accurately detect the wobble signal even during high-speed recording, the recording position positioning, the synchronization with the rotation speed, and the like can be performed stably. An optical disk device can be provided.
[0035]
An information processing apparatus according to a tenth aspect of the invention includes the optical disk apparatus according to the ninth aspect.
[0036]
Accordingly, since the optical disk apparatus according to claim 9 is built in, the wobble signal can be accurately detected even during high-speed recording. As a result, the optical disk apparatus corresponding to stable high-speed recording such as positioning of the recording position and synchronization with the rotation speed is possible. Can be provided.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. The optical disk apparatus according to the present embodiment shows an application example to an information recording / reproducing apparatus targeted for a recordable CD-R (CD-Recordable) optical disk 1. FIG. 1 is a schematic block diagram showing the configuration of the information recording / reproducing apparatus (drive apparatus).
[0038]
The schematic configuration and operation of the information recording / reproducing apparatus will be described with reference to FIG. The optical disk 1 is rotationally driven by a spindle motor 2 as rotational drive means. The spindle motor 2 is controlled by the motor driver 3 and the servo means 4 so that the linear velocity is constant (CLV) or the rotational speed is constant (CAV). The linear velocity can be changed in stages. The optical pickup 5 incorporates a semiconductor laser as a light source (not shown), an optical system, a focusing actuator, a tracking actuator, a light receiver, a position sensor, and the like, and irradiates the recording surface of the optical disc 1 with laser light.
[0039]
The optical pickup 5 can be moved in the sledge direction (disk radial direction) by a seek motor (not shown). These focusing actuators, tracking actuators, and seek motors are controlled by the motor driver 3 and the servo means 4 so as to position the laser spot at a target location on the optical disk 1 based on signals obtained from the light receiver and the position sensor.
[0040]
At the time of data reproduction, the reproduction signal obtained by the optical pickup 5 is amplified by the read amplifier 6 and binarized, and then input to the CD decoder 7 to perform deinterleaving and error correction. Further, the data after the deinterleaving and error correction processing is input to the CD-ROM decoder 8 to perform error correction processing for improving data reliability.
[0041]
Thereafter, the data processed by the CD-ROM decoder 8 is temporarily stored in the buffer RAM 10 by the buffer manager 9, and is transferred to the host side by the ATAPI / SCSI interface 11 when it is prepared as sector data. In the case of music data, the data output from the CD decoder 7 is input to the D / A converter 12 to extract an analog audio signal.
[0042]
On the other hand, when data is recorded, when data transferred from the host is received by the ATAPI / SCSI interface 11, the data is temporarily stored in the buffer RAM 10 by the buffer manager 9. Recording starts when a certain amount of data accumulates in the buffer RAM 10, but before that, the laser spot is positioned at the writing start point. The writing start point is obtained by an ATIP (Absolute Time In Pre-groove) signal which is a wobble signal preliminarily carved on the optical disc 1 by meandering tracks (pregrooves). The ATIP signal is time information indicating an absolute address on the optical disc. The ATIP decoder 13 extracts the ATIP signal information, detects an ATIP error, and measures the ATIP signal detection error rate.
[0043]
The synchronization signal generated by the ATIP decoder 13 is input to the CD encoder 14 so that data can be written at an accurate position. The data in the buffer RAM 10 is recorded on the optical disc 1 through the laser control circuit 16 as the light source drive control means and the optical pickup 5 after the error correction code is added and interleaved by the CD-ROM encoder 15 and the CD encoder 14.
[0044]
Such an information recording / reproducing apparatus includes a microcomputer 20 including a CPU 17, a ROM 18, and a RAM 19 for controlling the operation of each unit described above.
[0045]
Here, in the present embodiment, as the optical disk 1, an optical disk 1 in which an ATIP signal as a wobble signal is formed in advance by meandering tracks (pregrooves) is used. Further, as a data pattern to be written for causing the light source to emit light and writing to the optical disc 1, an EFM (Eight to Fourteen Modulation) signal of a CD system standard is used. Further, in the light receiver included in the optical pickup 5, in order to detect a track error signal, the light receiving elements C and D (divided into two in the tangential direction of the track (pre-groove) and receive the reflected light from the track respectively. A photodiode 21 having a photodiode structure is provided. The light receiving element may be divided into two in the tangential direction of the track, and it does not matter whether the light receiving element is divided in the direction perpendicular to the track. Therefore, it may be a so-called quadrant photoreceiver that also uses a track error signal and an RF signal and a focus error signal. Further, the structure is not limited to the divided structure of the light receiving surface of the same light receiver, and may be a structure in which two light receiving elements are arranged in parallel.
[0046]
A configuration example of an ATIP signal detection device as a wobble signal detection device in the present embodiment will be described with reference to FIG. 2 under the basic configuration as such an information recording / reproduction device. This ATIP signal detection device is mainly composed of a read amplifier 6 and outputs the detected ATIP signal to the ATIP decoder 13.
[0047]
First, in this ATIP signal detection device, light receiving elements C and D having a two-divided structure for detecting a track error signal are used as a signal input source. Current-voltage conversion amplifiers (I / V amplifiers) 22 and 23 for converting the current signals into voltage signals and outputting them are connected to the output sides of the light receiving elements C and D. Band limiting circuits 24 and 25 are connected to the output sides of these I / V amplifiers 22 and 23, respectively, and signal waveform correction circuits 26 and 27 as correction circuits are connected. Connected to the output side of the signal waveform correction circuits 26 and 27 is a subtracter 28 as a difference signal detection circuit that takes the difference between the signals. A low-pass filter (BPF) 29 and a binarization circuit 30 are sequentially connected to the output side of the subtracter 28.
[0048]
  The band limiting circuits 24 and 25 are configured by a low-pass filter (BPF) in which a cutoff frequency for band limiting is set so as to remove the frequency component of the EFM signal that is a data pattern to be written. More specifically, the frequency of the ATIP signal is f_ATIP, The cutoff frequency of the band limiting circuits 24 and 25 is f_C, The frequency of the EFM signal is f_EFMWhen
  f_ATIP≪f_C≪f_EFM
It is set to satisfy. That is, the cutoff frequency is f_CIs the frequency f of the EFM signal to be excluded_EFMThan enoughLowAnd the frequency f of the ATIP signal to be detected_ATIPThan enoughhighThe frequency is set. For example, the ATIP signal is generally modulated at a frequency of about 22 kHz at the time of recording at 1 × speed, but becomes about 200 kHz at the time of recording at 10 × speed, and the frequency f of the EFM signal is_EFMIs 1MHz at 1x speed and 10MHz at 10x speed, so in the case of a model that assumes 10x speed,
  f_ATIP= 200 kHz << f_C≪f_EFM= 10MHz
Is set to satisfy the relationship. In this case, the cutoff frequency f_C(Bandwidth limit frequency) As much as possible to satisfy the above relationshipLowFrequency (frequency f of ATIP signal_ATIPIt is preferable to set it to a frequency close to that. Cut-off frequency f_CIn the above example, (band-limited frequency) is set to 1 MHz, for example. Incidentally, the cutoff frequency of the low-pass filter 29 at the subsequent stage is the frequency f of the ATIP signal to be detected._ATIPThe frequency at which the component can be extracted (therefore, the cut-off frequency f of the band limiting circuits 24 and 25)_CIs set sufficiently higher than the cut-off frequency of the low-pass filter 29).
[0049]
Specifically, the signal waveform correction circuits 26 and 27 can take various configuration examples as in the embodiments described later, but the point is that the light receiving elements C and D inputted through the band limiting circuits 24 and 25 are used. The waveform equalization processing is performed so that the signal amplitudes of the two systems are uneven.
[0050]
In such a configuration, when writing is performed on the optical disc 1 by laser light from a semiconductor laser, reflected light from the track is received by the respective light receiving elements C and D in the light receiver 21, and the amount of received light is A corresponding current is output. These current signals are converted into voltage signals by the I / V amplifiers 22 and 23, respectively. The output waveforms of these I / V amplifiers 22 and 23 return the reflected light from the optical disc 1 with the same waveform as the light emission state even when the semiconductor laser emits light according to the EFM pattern which is a data pattern to be written. However, by recording information on the surface of the optical disc 1 (by irradiating laser light), a chemical change occurs on the recording surface and the reflectance changes. For example, the waveform in FIG. As shown to A and B, reflected light shows a remarkable change. In the case of high-speed recording such as 10 × speed, such a remarkable change occurs at a high speed.
[0051]
Here, in Japanese Patent Laid-Open No. 10-11757 described above, noise components caused by the EFM pattern are removed by sample-holding each portion corresponding to the space (see FIG. 8) of the EFM pattern where the reflected light is stable. However, at the time of high-speed recording of 10 times speed or more, as described above, the space portion also becomes high-speed and shortens in time, and the light emission pattern itself tends to become shorter and shorter. For this reason, the sample-and-hold method cannot effectively cope with it. Further, it is conceivable to hold the peak as shown by the waveforms A and B in FIG. 8, but at the time of high speed recording of 10 times or higher, the peak hold circuit also changes to the EFM pattern that changes at such high speed. The tracking cannot be followed, and the peak hold value variation between the two systems is large. Even if the difference between the two systems is taken, the EFM pattern component remains, and the ATIP signal cannot be detected accurately.
[0052]
In this regard, in the present embodiment, for example, the signal waveform correction circuits 26 and 27 detect the peak values of the signals output from the I / V amplifiers 22 and 23, and the waveforms or the like so that the signal waveforms match. However, prior to this process, the band is limited so as to remove the frequency component of the EFM pattern by passing through the band limiting circuits 24 and 25. Therefore, at the time of high-speed recording of 10 times speed or more. Even in such a case, the signal waveform correction circuits 26 and 27 can perform processing such as peak value detection that is not affected by the EFM pattern. That is, by limiting the band through the band limiting circuits 24 and 25, the components of the EFM pattern included in the signals output from the I / V amplifiers 22 and 23 are smoothed, and the C / N is attributed to the components of the EFM pattern. The signal state with less noise component that deteriorates the ratio is obtained, and the signal waveform correction circuits 26 and 27 can perform processing such as peak value detection substantially at a low speed.
[0053]
The signals subjected to the waveform equalization processing by the signal waveform correction circuits 26 and 27 in this way are input to the subtractor 28 to obtain a difference between the two, and further through the low-pass filter 29, near the ATIP signal. By extracting only the frequency component and binarizing by the binarization circuit 30, an accurate digitized ATIP signal can be obtained.
[0054]
As described above, according to the present embodiment, during the recording operation on the optical disc 1 by emitting the semiconductor laser in accordance with the EFM pattern, each output from the light receiving elements C and D having the two-divided configuration. The band limiting circuits 24 and 25 remove the frequency components of the EFM pattern unrelated to the ATIP signal before the signal waveform correction circuits 26 and 27 perform waveform equalization processing so that the signals are equal to each other. Since the signal input to the signal waveform correction circuits 26 and 27 is in a form from which the frequency component of the EFM pattern has been removed, the signal waveform correction circuits 26 and 27 can be used even during high-speed recording. Waveform equalization processing that is not affected by noise components generated from high-speed EFM patterns can be performed, and each signal output from such signal waveform correction circuits 26 and 27 can be processed. By taking the difference by the subtracter 28, ATIP signal is detected accurately. That is, an ATIP signal can be accurately detected with a simple configuration without using a sample-and-hold method that has a limit on high-speed response. Therefore, since the information recording / reproducing apparatus is accurate even when the ATIP signal is detected at the time of high-speed recording, the positioning for recording information can be performed accurately, and the rotation speed of the optical disc 1 for recording information can be accurately determined. Control to synchronize with can be performed properly.
[0055]
A second embodiment of the present invention will be described with reference to FIGS. The same parts as those shown in the first embodiment are denoted by the same reference numerals, and description thereof is also omitted (the same applies to the following embodiments).
[0056]
The present embodiment shows an example in which the ATIP signal detection apparatus is configured so as to eliminate the influence of track deviation on ATIP signal detection.
[0057]
First, the signals obtained from the light receiving elements C and D when the center of the optical spot by the objective lens is deviated from the track center of the optical disc 1 will be described with reference to FIG. FIG. 3B shows a state where the center of the optical spot is on the track center. In this case, the amounts of incident light to the light receiving elements C and D are equal. Therefore, the output waveforms obtained from the respective light receiving elements C and D are also equal, and the ATIP signal obtained by taking the difference between them has a good C / N ratio. The track error signal represented by the difference between the outputs of the light receiving elements C and D represents a reference value (track error signal = 0).
[0058]
On the other hand, FIG. 3A shows a case where the center of the optical spot is shifted to the light receiving element C side with respect to the track, and the amount of incident light with respect to the light receiving element C on the off-track side is reduced. The amount of incident light on the light receiving element D increases. As a result, the output waveforms from the light receiving elements C and D are such that the output on the light receiving element C side is small and the output on the light receiving element D side is large. Therefore, the ATIP signal obtained by taking these differences is the C / N ratio. Will be bad. Further, the shift of the track error signal represented by the difference between the outputs of the light receiving elements C and D appears on the negative side.
[0059]
3C shows a case where the center of the optical spot is shifted to the light receiving element D side with respect to the track, and the incident light quantity to the light receiving element D on the off-track side is reduced, and the track center side is shown. The amount of incident light on the light receiving element C increases. As a result, the output waveform from the light receiving elements C and D has a larger output on the light receiving element C side and a smaller output on the light receiving element D side. Therefore, the ATIP signal obtained by taking these differences is the C / N ratio. Will be bad. Further, the shift of the track error signal represented by the difference between the outputs of the light receiving elements C and D appears on the positive side.
[0060]
For this reason, in this embodiment, as shown in FIG. 4, each of the signal waveform correction circuits 26 and 27 is composed of variable gain amplifiers 31 and 32, and a track error signal monitor for monitoring the track A signal. A track error signal detection system 33 as means is provided, and the gain of each of the variable gain amplifiers 31 and 32 is variably set by the CPU 17 in accordance with the deviation amount of the track error signal monitored by the track error signal detection system 33. It is configured. The track error signal detection system 33 is constituted by a known detection system for detecting a track error signal, and the deviation amount of the track error signal is the center of the track error signal as shown in FIG. 3 (reference value = 0). It can be detected by the amount of off-track from. Further, the displacement direction is also detected by the positive and negative.
[0061]
Therefore, in the normal case as shown in FIG. 4B, the gains of the variable gain amplifiers 31 and 32 for the light receiving elements C and D are set equal, but the case as shown in FIG. 4 is variably set so that the gain on the gain variable amplifier 31 side is larger than the gain of the gain variable amplifier 32. Conversely, in the case shown in FIG. 4C, the gain variable amplifier 32 side is set. Is variably set so as to be larger than the gain of the variable gain amplifier 31, and in either case, the signal amplitude of each of the light receiving elements C and D is corrected so as to be equal without being affected by the track offset. .
[0062]
Therefore, according to the present embodiment, even if high-speed recording is performed in a state where there is a track shift, the two variable signals based on the light-receiving elements C and D by the gain variable amplifiers 31 and 32 as described above. Therefore, the noise component generated from the EFM pattern that is not related to the ATIP signal included in the signal obtained during recording can be efficiently removed, and as a result, the ATIP signal can be accurately obtained. Can be detected.
[0063]
A third embodiment of the present invention will be described with reference to FIGS.
This embodiment shows an example in which an ATIP signal detection apparatus is configured so as to eliminate the influence of lens shift on ATIP signal detection.
[0064]
First, the signals obtained from the light receiving elements C and D when the light receiving elements C and D are displaced from the center of the optical axis of the objective lens will be described with reference to FIG. FIG. 5B shows a state where the center of the light receiver 21 is on the optical axis of the objective lens. In this case, the amounts of incident light on the light receiving elements C and D are equal. Therefore, the output waveforms obtained from the respective light receiving elements C and D are also equal, and the ATIP signal obtained by taking the difference between them has a good C / N ratio. The lens position signal represented by the difference between the outputs of the light receiving elements C and D represents a reference value (lens shift amount = 0).
[0065]
On the other hand, FIG. 5A shows a case where the center of the light receiver 21 is shifted to the light receiving element D side with respect to the optical axis of the objective lens, and the amount of incident light with respect to the light receiving element C is reduced. Incident light quantity for D increases. As a result, the output waveforms from the light receiving elements C and D are such that the output on the light receiving element C side is small and the output on the light receiving element D side is large. Therefore, the ATIP signal obtained by taking these differences is the C / N ratio. Will be bad. Further, the shift amount of the lens position signal represented by the difference between the outputs of the light receiving elements C and D appears on the negative side.
[0066]
FIG. 5C shows a case where the center of the light receiver 21 is shifted to the light receiving element C side with respect to the optical axis of the objective lens, and the amount of incident light with respect to the light receiving element D is reduced. Incident light quantity for C increases. As a result, the output waveform from the light receiving elements C and D has a larger output on the light receiving element C side and a smaller output on the light receiving element D side. Therefore, the ATIP signal obtained by taking these differences is the C / N ratio. Will be bad. Further, the shift amount of the lens position signal represented by the difference between the outputs of the light receiving elements C and D appears on the positive side.
[0067]
For this reason, in the present embodiment, as shown in FIG. 6, each of the signal waveform correction circuits 26 and 27 is constituted by the gain variable amplifiers 34 and 35, and the lens position signal monitor for monitoring the lens position signal. A lens position signal detection system 36 as a means is provided, and the gain of each of the variable gain amplifiers 34 and 35 is adjusted by the CPU 17 in accordance with the shift amount (lens shift amount) of the lens position signal monitored by the lens position signal detection system 36. It is configured to be variably set. The lens position signal detection system 36 is constituted by a known detection system for detecting a lens position signal using a difference signal between the light receiving elements C and D. The amount of deviation of the lens position signal is as shown in FIG. It can be detected by the amount of lens shift from the center of the lens position signal (reference value = 0). Further, the displacement direction is also detected by the positive and negative.
[0068]
Therefore, in the normal case as shown in FIG. 5B, the gains of the variable gain amplifiers 34 and 35 for the light receiving elements C and D are set equal, but the case as shown in FIG. 5 is variably set so that the gain on the gain variable amplifier 34 side is larger than the gain of the gain variable amplifier 35. Conversely, in the case shown in FIG. 5C, the gain variable amplifier 35 side is set. Is variably set so as to be larger than the gain of the variable gain amplifier 34, and in either case, the signal amplitude of each of the light receiving elements C and D is corrected so as to be equal without being affected by the lens shift. .
[0069]
Therefore, according to the present embodiment, even when high-speed recording is performed in a state where there is a lens shift, the two variable signals based on the light receiving elements C and D by the variable gain amplifiers 34 and 35 as described above. Therefore, the noise component generated from the EFM pattern that is not related to the ATIP signal included in the signal obtained during recording can be efficiently removed, and as a result, the ATIP signal can be accurately obtained. Can be detected.
[0070]
A fourth embodiment of the present invention will be described with reference to FIGS. This embodiment shows a configuration example of a correction circuit in an ATIP signal detection device.
[0071]
The correction circuit 37 in the present embodiment includes gain variable amplifiers 38 and 39 to which signals that have passed through the band limiting circuits 24 and 25, respectively, and peak values (maximum values) of signals output from these gain variable amplifiers 38 and 39. ) And the peak values detected by these peak detectors 40 and 41 are compared, and the gains of the variable gain amplifiers 38 and 39 are feedback-controlled so that the peak values are equal. The output of the variable gain amplifiers 38 and 39 is input to the subtracter 28 as a signal after waveform equalization processing.
[0072]
In such a configuration, the outputs of the respective light receiving elements C and D (voltages by the I / V amplifiers 22 and 23) obtained when the information recording / reproducing apparatus records information on the optical disc 1 according to the EFM pattern. When considering the waveforms of the outputs (Vc, Vd converted into signals), it is as shown in FIG. That is, the emission waveform of the semiconductor laser when information is recorded according to the EFM pattern is generally such that a large power (recording power) square wave is emitted when writing a mark for recording, and the information is emitted when the mark is not written. Is a waveform that emits light with the same weak power (reproduction power) as in the case of reproducing. However, the output waveforms of the light receiving elements C and D that actually receive the reflected light from the optical disc 1 with respect to such a light emission waveform change in reflectance over time at the same time as mark writing is started. In this case, the waveforms become complicated as indicated by A and B in FIG. In addition, the output waveforms from the light-receiving elements C and D having the two-divided configuration are caused by various factors such as sensitivity variations of the I / V amplifiers 22 and 23, the above-described track error signal offset, and lens shift. The signals are output in a state where the amplitudes of the two systems of signals vary greatly.
[0073]
Under such circumstances, in the present embodiment, the maximum value Vc of the output voltage after I / V conversion and band limitation obtained from the respective light receiving elements C and D._PEAK, Vd_PEAKAre detected by the peak detectors 40 and 41, respectively, and the detected maximum value Vc is detected._PEAK, Vd_PEAKWhen they do not coincide with each other by the comparator 42, these maximum values Vc_PEAK, Vd_PEAKThe gains of the variable gain amplifiers 38 and 39 are set to increase or decrease so that they match each other. In the example shown in FIG. 8A, by increasing the gain of the gain variable amplifier 38 of the system on the light receiving element C side and decreasing the gain of the gain variable amplifier 39 of the system on the light receiving element D side, ) Maximum value V'c of both systems as shown in_PEAK, V'd_PEAKOutput voltages V′c and V′d subjected to waveform equalization processing so as to match each other are obtained from the gain variable amplifiers 38 and 39. Therefore, an accurate ATIP signal is detected by taking the difference between the output voltages V′c and V′d having the same maximum value in the subtractor 28.
[0074]
  As described above, according to the present embodiment, the light is output from the light receiving elements C and D having the two-divided configuration while the semiconductor laser emits light according to the EFM pattern to be written and the recording operation is performed on the optical disc 1. When the waveform equalization processing is performed on each signal by the correction circuit 37 so that the signals are equal to each other, the frequency component of the ATIP signal to be detected is considerably higher than the frequency component.highSince the frequency components of the EFM pattern are removed in advance by the band limiting circuits 24 and 25, the correction circuit 37 performs a waveform equalization process that is not affected by the frequency components of the EFM pattern, and the maximum value V of each signal amplitude. 'C_PEAK, V'd_PEAKCan be simplified. Specifically, the peak detectors 40 and 41, the comparator 42, etc. may be used, and the realization becomes easy.
[0075]
However, the comparator 42 that compares the maximum values of the two systems is not essential, and is configured so that correction control is independently performed for each system so that the maximum value detected in each system becomes a constant value. Also good.
[0076]
A fifth embodiment of the present invention will be described with reference to FIGS. This embodiment also shows a configuration example of a correction circuit in the ATIP signal detection device. Basically, this is the same as in the case of the fourth embodiment, but in this embodiment, an effective value is used instead of the maximum value (peak value).
[0077]
That is, the correction circuit 43 in the present embodiment calculates the effective values of the gain variable amplifiers 44 and 45 to which the signals that have passed through the band limiting circuits 24 and 25 are input and the signals output from these gain variable amplifiers 44 and 45, respectively. The effective value detectors 46 and 47 to be detected are compared with the effective values detected by these effective value detectors 46 and 47, and the gains of the variable gain amplifiers 44 and 45 are feedback-controlled so that the effective values are equal. The output of the variable gain amplifiers 44 and 45 is input to the subtractor 28 as a signal after waveform equalization processing.
[0078]
Under the situation described with reference to FIG. 8 (see FIG. 10), in this embodiment, the effective value Vc of the output voltage after I / V conversion and band limitation obtained from each of the light receiving elements C and D is obtained._RMS, Vd_RMSAre detected by the effective value detectors 46 and 47, respectively, and the detected effective value Vc is detected._RMS, Vd_RMSIf they do not coincide with each other by the comparator 48, these effective values Vc_RMS, Vd_RMSThe gains of the variable gain amplifiers 44 and 45 are set to increase or decrease so that they match each other. In the example shown in FIG. 10A, the gain of the gain variable amplifier 44 of the system on the light receiving element C side is increased, and the gain of the gain variable amplifier 45 of the system on the light receiving element D side is reduced, thereby reducing the gain of FIG. ) Effective value V'c of both systems as shown in_RMS, V'd_RMSOutput voltages V′c and V′d subjected to waveform equalization processing so as to match each other are obtained from the gain variable amplifiers 44 and 45. Therefore, an accurate ATIP signal is detected by taking the difference between the output voltages V′c and V′d having the same effective value in the subtractor 28.
[0079]
  As described above, according to the present embodiment, the light is output from the light receiving elements C and D having the two-divided configuration while the semiconductor laser emits light according to the EFM pattern to be written and the recording operation is performed on the optical disc 1. When each signal is subjected to waveform equalization processing by the correction circuit 43 so that the signals are equal to each other, the frequency components of the ATIP signal to be detected are considerably different.highSince the frequency components of the EFM pattern are removed in advance by the band limiting circuits 24 and 25, the effective value V of each signal amplitude is used in the correction circuit 43 as a waveform equalization process that is not affected by the frequency components of the EFM pattern. 'C_RMS, V'd_RMSCan be simplified. Specifically, the effective value detectors 46 and 47, the comparator 48, etc. may be used, and the realization becomes easy.
[0080]
However, the comparator 48 for comparing the effective values of the two systems is not indispensable, and is configured so as to perform correction control independently for each system so that the effective values detected in each system become constant values. Also good.
[0081]
A sixth embodiment of the present invention will be described with reference to FIG. In the present embodiment, as the band limiting circuits 22 and 23, those whose band limiting frequency can be variably set (including switching selection) are used, and the band limiting frequency according to the recording speed (writing speed) given from the CPU 17 is used. Is configured to be variably set.
[0082]
The ATIP signal is a signal obtained by FM-modulating a carrier wave of a specific frequency (generally 22.05 kHz), and the frequency of this carrier wave changes as the information recording speed (write speed) changes. That is, when the writing speed is 10 times faster, the frequency component of the ATIP signal is about 200 kHz. Therefore, in the present embodiment, the frequency of the band limiting circuits 22 and 23 is also varied in accordance with the change of the recording speed, so that the frequency component of the EFM pattern is removed without losing the ATIP signal at the recording speed. It is possible to apply a bandwidth limit suitable for.
[0083]
Therefore, according to the present embodiment, band limitation suitable for the writing speed is possible, and as a result, the wobble signal can always be accurately detected regardless of the writing speed. In other words, the specification is applicable not only at high-speed recording but also at low-speed recording.
[0084]
A seventh embodiment of the present invention will be described with reference to FIG. This embodiment is applied to a personal computer 51 as an information processing apparatus. In addition to the 3.5-inch FD drive apparatus 52, an optical disk apparatus 53 which is an information recording / reproducing apparatus as described above is used as a CD-R drive. As a built-in type (either a built-in type or a so-called built-in type). Therefore, the host is also built in the personal computer 51.
[0085]
According to such a personal computer 51, since the optical disk device 53 provided with the ATIP signal detection device as described above is built in, the ATIP signal can be transmitted even during an actual recording operation, particularly during high-speed recording. As a result, it is possible to provide the personal computer 51 that can use the optical disk device 53 that can stably detect high-speed recording, such as positioning of the recording position and synchronization with the rotation speed, as a storage device.
[0086]
However, the present invention is not limited to the type of optical disk device built in the personal computer 51, but may be a single optical disk device connected to an information processing device such as an external host. Further, the portable personal computer 51 is not limited to the desktop personal computer 51 and may be a portable computer such as a notebook computer.
[0087]
In the above-described embodiment, the case where the ATIP signal is used as the wobble signal has been described as an example. However, the present invention is not limited to the ATIP signal. For example, an ADIP (Address In Pre-groove) signal in which address information is recorded in a pregroove is used. Etc. In the above-described embodiment, the CD system, in particular, the CD-R is assumed, and the example of using the EFM signal as an example of the data pattern to be written has been described. However, the example of the data pattern according to the specification of the recordable optical disc may be used. What is necessary is not limited to the EFM signal.
[0088]
【The invention's effect】
According to the wobble signal detecting device of the first aspect of the present invention, each of the light output from the light receiving element having the two-divided structure is performed while the light source is emitted according to the data pattern to be written and the recording operation is performed on the optical disc. Before performing the waveform equalization processing so that the signals are equalized by the correction circuit, the band limiting circuit limits the band so as to remove the frequency component of the data pattern to be written that is not related to the wobble signal. As a result, the signal input to the correction circuit has a form in which the frequency component of the data pattern to be written is removed. Therefore, even during high-speed recording, the correction circuit is influenced by the noise component generated from the data pattern to be written. Waveform equalization processing is possible, and the difference signal detection circuit can take the difference between the signals output from such a correction circuit. Accordingly, it is possible to accurately detect the wobble signal. That is, a wobble signal can be accurately detected with an easy configuration without using a sample-and-hold method with a limit in high-speed response.
[0089]
  According to the second aspect of the invention, the frequency component of the wobble signal is considerably higher than the frequency component of the data pattern to be written.LowFocusing on this point, in the wobble signal detection device according to claim 1, the band limiting frequency of the band limiting circuit is set to be higher than the frequency component of the data pattern to be written to be removedLowAnd the frequency of the wobble signal to be detectedhighBy setting the frequency, for example, a low-pass filter that satisfies such a frequency condition can be easily realized as a band limiting circuit. In particular, the bandwidth limit frequency is sufficiently higher than the frequency component of the data pattern.LowAnd well above the frequency of the wobble signalhighFrequency, as much as possibleLowIf the frequency is used, the frequency component of the data pattern can be removed as much as possible without hindering the wobble signal to be detected, and a more preferable signal can be obtained.
[0090]
According to the invention of claim 3, in the wobble signal detection device of claim 1 or 2, as a specific application example, when high-speed recording is performed on a write-once optical disc using an EFM signal, the ATIP signal is accurately detected. Can be detected.
[0091]
According to the fourth aspect of the present invention, in the wobble signal detection device according to any one of the first to third aspects, the optical disk is one of the factors that change the amplitude of each signal from the light receiving element divided into two. There is a track shift in which the position of the optical spot deviates from the center of the track. Such a track error signal is monitored by a general track error signal monitoring means, and the waveform equalization processing in the correction circuit is performed according to the error amount. Since the correction amount is variably set, even if high-speed recording is performed in a state where a track shift has occurred, the two systems of signals are corrected to be equal, so that the wobble included in the signal obtained during recording The noise component generated from the data pattern to be written, which is not related to the signal, can be efficiently removed. It is possible to detect in.
[0092]
According to a fifth aspect of the present invention, in the wobble signal detection device according to any one of the first to third aspects, the light reception is one of the factors that change the amplitude of each signal from the light receiving element divided into two. Although there is a lens shift in which the element deviates from the center of the objective lens, a lens position signal indicating such a lens shift is monitored by a general lens position signal monitoring means, and waveform equalization processing in a correction circuit is performed according to the shift amount. By variably setting the correction amount, the wobble signal included in the signal obtained during recording is corrected even if high-speed recording is performed in a state where a lens shift has occurred, so that the two signals are corrected to be equal. The noise component generated from the data pattern to be written, which has nothing to do with it, can be efficiently removed, resulting in accurate detection of the wobble signal. .
[0093]
  According to a sixth aspect of the present invention, in the wobble signal detection device according to any one of the first to third aspects, a light source is emitted according to a data pattern to be written and a recording operation is being performed on the optical disc. In addition, when each signal output from the light receiving element having the two-divided configuration is subjected to waveform equalization processing so that the signals are equalized by the correction circuit, it is considerably higher than the frequency component of the wobble signal to be detected.highSince the frequency component of the data pattern to be written is removed in advance by the band limiting circuit, the maximum value of each signal amplitude is set as a waveform equalization process that is not affected by the frequency component of the data pattern to be written in the correction circuit. A simple process can be made constant. Specifically, a peak detection circuit, a comparator, or the like may be used, which can be easily realized.
[0094]
  According to the seventh aspect of the present invention, in the wobble signal detecting device according to any one of the first to third aspects, the light source is emitted according to the data pattern to be written and the recording operation is being performed on the optical disc. In addition, when each signal output from the light receiving element having the two-divided configuration is subjected to waveform equalization processing so that the signals are equalized by the correction circuit, it is considerably higher than the frequency component of the wobble signal to be detected.highSince the frequency component of the data pattern to be written is removed in advance by the band limiting circuit, the effective value of each signal amplitude is obtained as a waveform equalization process that is not affected by the frequency component of the data pattern to be written in the correction circuit. A simple process can be made constant. Specifically, an effective value detection circuit, a comparator, or the like may be used, and the process can be easily realized.
[0095]
According to an eighth aspect of the present invention, in the wobble signal detection device according to any one of the first to seventh aspects, the wobble signal is a signal obtained by FM-modulating a carrier having a specific frequency, and the carrier records information. When the writing speed to be changed changes, the band limiting frequency of the band limiting circuit is also variably set according to the change of the writing speed, so that band limitation suitable for the writing speed is possible, The wobble signal can be accurately detected regardless of the writing speed, and can cope with not only high-speed recording but also low-speed recording.
[0096]
According to the optical disk apparatus of the ninth aspect of the present invention, since the wobble signal detection apparatus according to any one of the first to eighth aspects can be accurately detected even during high-speed recording, the recording position is determined. In addition, it is possible to provide an optical disc apparatus that is capable of stable high-speed recording such as synchronization with the rotational speed.
[0097]
According to the information processing apparatus of the tenth aspect of the present invention, since the optical disk apparatus according to the ninth aspect is built in, the wobble signal can be accurately detected even during high-speed recording. It is possible to provide an information processing apparatus that can use an optical disc apparatus that is compatible with stable high-speed recording such as synchronization with respect to the recording medium.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing a configuration of an information recording / reproducing apparatus showing a first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration example of the ATIP signal detection apparatus.
FIG. 3 is an explanatory diagram for explaining a track offset according to a second embodiment of the present invention.
FIG. 4 is a block diagram showing a configuration example of an ATIP signal detection apparatus according to a second embodiment of the present invention.
FIG. 5 is an explanatory diagram for explaining a lens shift according to a third embodiment of the present invention.
FIG. 6 is a block diagram showing a configuration example of an ATIP signal detection apparatus according to a third embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration example of an ATIP signal detection apparatus according to a fourth embodiment of the present invention.
FIG. 8 is an output waveform diagram showing the state before and after the gain adjustment.
FIG. 9 is a block diagram showing a configuration example of an ATIP signal detection apparatus according to a fifth embodiment of the present invention.
FIG. 10 is an output waveform diagram showing the state before and after the gain adjustment.
FIG. 11 is a block diagram showing a configuration example of an ATIP signal detection apparatus according to a sixth embodiment of the present invention.
FIG. 12 is a schematic perspective view illustrating a configuration example of a personal computer according to a seventh embodiment of the present invention.
[Explanation of symbols]
1 Optical disc
2 Rotation drive means
5 Optical pickup
16 Light source drive control means
24,25 Band-limiting circuit
26, 27 Correction circuit
28. Difference signal detection circuit
33 Track error signal monitoring means
36 Lens position error signal monitoring means
37 Correction circuit
43 Correction circuit
53 Optical disk device
C, D light receiving element

Claims (10)

A wobble signal detection device for detecting a wobble signal of a pregroove formed on a recordable optical disc,
A light receiving element that is divided into two in the tangential direction of the pregroove and receives reflected light from the pregroove;
A band limiting circuit for band-limiting to a low-pass characteristic so as to remove a frequency component of a data pattern to be written to the optical disk by a light source for each signal output from these light receiving elements;
A correction circuit that performs waveform equalization processing so that the amplitude of each signal output from the band limiting circuit is equal;
A wobble signal detection apparatus comprising: a difference signal detection circuit that obtains a difference between the signals output from the correction circuit. The band limiting circuit has a low-pass characteristic in which a cutoff frequency is set lower than a frequency component of the data pattern to be written and higher than a frequency of a wobble signal. The wobble signal detection device according to 1. 2. The optical disk is a write-once optical disk, the wobble signal is an ATIP (Absolute Time In Pre-groove) signal, and the data pattern to be written is an EFM (Eight to Fourteen Modulation) signal. Or the wobble signal detection apparatus of 2 description. 4. The correction amount of the waveform equalization processing in the correction circuit is variably set according to the shift amount of the track error signal monitored by the track error signal monitoring means. The wobble signal detection device described. 4. The correction amount of the waveform equalization processing in the correction circuit is variably set according to the shift amount of the lens position signal of the objective lens monitored by the lens position signal monitoring means. A wobble signal detection device according to claim 1. The wobble according to any one of claims 1 to 3, wherein the waveform equalization processing in the correction circuit is processing for making the maximum value of each signal amplitude output from the band limiting circuit constant. Signal detection device. The wobble according to any one of claims 1 to 3, wherein the waveform equalization processing in the correction circuit is processing for making an effective value of each signal amplitude output from the band limiting circuit constant. Signal detection device. 8. The wobble signal detection apparatus according to claim 1, wherein the band limiting circuit is capable of variably setting a band limiting frequency according to a writing speed. Rotation driving means for rotating and driving a recordable optical disc on which a pre-groove having a wobble signal is formed;
An optical pickup having a light source and an objective lens for condensing and irradiating light from the light source onto the pre-groove of the optical disc, and movable in the radial direction of the optical disc;
Light source drive control means for causing the light source to emit light according to a data pattern to be written at the time of recording;
The wobble signal detection device according to any one of claims 1 to 8, wherein the optical pickup includes a light receiving element that is divided into two in a tangential direction of the pregroove and receives light reflected from the pregroove.
An optical disc apparatus comprising: An information processing apparatus comprising the optical disk device according to claim 9.

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