JP2005004862A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device capable of preventing a read error. <P>SOLUTION: Disk ID information having track distortion, a physical address for specifying the place of distortion, and an offset start position information are stored in advance into an non-volatile memory. According to a specified track offset profile, addition to a tracking error signal is made in recording for controlling tracking to record data. Coarse and fine recording is avoided in the place of track distortion and a read error is eliminated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk apparatus mounted on or connected to an electronic device such as a computer, and more particularly to tracking correction during recording of an optical disk apparatus using tracking servo control by a push-pull method.
[0002]
[Prior art]
In tracking servo control of optical discs, a method called the push-pull method, which generates a tracking error signal based on the balance of the light receiving element output obtained by dividing the reflected beam parallel to the track, is used. Control is performed so that is zero.
[0003]
Further, in a recordable optical disc medium, there is a case where a stamper which is an original master disc is in a poorly molded state in a disc manufacturing process, and a servo signal may be partially distorted. This is because the groove pitch, groove depth and groove shape of the disk are due to the cutting failure of the master disk, and the disks manufactured with such a master disk all have the same track distortion at the same location, This will have a large effect on the tracking control system. In particular, since the groove depth is shallow for a rewritable disc such as a DVD-RW, the amplitude value of the servo signal is small, and the influence on the tracking error signal is particularly large for some distortion of the groove shape. In such a disk, when the tracking control by the push-pull method is performed, the roughness of the track pitch is caused at the distortion portion. When recording the outer track, the distorted track may cause cross-erase of the information on the inner track, resulting in a local error rate that may be unreadable even in the worst case. is there.
[0004]
Therefore, conventionally, the influence from the adjacent track has been avoided by setting the recording power to be lower than the optimum recording power.
[0005]
[Patent Document 1]
JP 60-663340 A
[0006]
[Problems to be solved by the invention]
However, when the conventional recording power is set low, there is a problem that the modulation rate is lowered as a whole and the error rate is deteriorated. In addition, since the roughness of the track pitch itself is not improved at the distorted track portion, the influence from the adjacent track cannot be completely avoided and a reading error may occur.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described conventional problems, and to provide an optical disc apparatus capable of preventing occurrence of a reading error.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, an optical disc apparatus of the present invention stores disc ID information having track distortion, a physical address for specifying a distortion location, and offset start position information in a nonvolatile memory in advance, and a predetermined track offset. According to the profile, the data is recorded by performing tracking control by adding to the tracking error signal during recording.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 is a recordable / reproducible optical disc apparatus having a tracking error extracting means based on a push-pull signal, an adding means for adding a tracking offset value, and a tracking control means for an optical pick. A plurality of specified track distortion locations are stored as table information in a nonvolatile memory, and in a recording operation including the distortion locations, a tracking offset is changed stepwise according to a predetermined offset profile and added to record data. The optical disc apparatus is characterized in that it has an effect of avoiding recording errors at a track distortion location and eliminating read errors.
[0010]
According to a second aspect of the present invention, the registration information of each distortion location has start position information of tracking offset correction measured from two ECC blocks before, and adjusts the timing of track offset addition based on the start position information. The optical disk apparatus according to claim 1, wherein the optical disk apparatus has an operation of obtaining an accurate correction timing of a track distortion portion.
[0011]
The invention according to claim 3 is characterized in that the offset profile of the stepwise tracking offset has a length of at least one period of the disk, and the polarity of the offset is reversed at a position sandwiching the distortion portion. 1 is an optical disc apparatus according to 1 which has an effect of correcting a pitch between two tracks sandwiching a track distortion portion at equal intervals.
[0012]
The invention according to claim 4 is characterized in that the registration information of each distortion location includes tracking offset amplitude weight information, and a constant coefficient is multiplied and added based on the weight information. In the described optical disk apparatus, the track pitch is corrected more accurately in accordance with the degree of track distortion.
[0013]
According to a fifth aspect of the present invention, the registration information of each distortion location has a correction number information bit, and correction is performed by repeating an offset profile a plurality of times in accordance with the correction number information bit. The optical disk device has an action corresponding to a location where track distortion is continuously generated.
[0014]
According to the sixth aspect of the invention, the type of the optical disk is specified by reading information on a predetermined portion of the optical disk, it is determined whether or not the optical disk is stored in the storage means, and the optical disk stored in the storage means is determined. In this case, a portion where the track distortion is generated on the optical disk is read from the storage means, and an off-track amount specific to the track distortion portion is read from the storage means, and the track distortion portion is recorded when the track distortion portion is recorded. This is an optical recording method characterized in that tracking is performed in consideration of the off-track amount, and it has the effect of avoiding recording errors at a track distortion location and eliminating read errors.
[0015]
The invention according to claim 7 is the optical recording method according to claim 6, wherein the optical disk is specified by information corresponding to the manufacturer stored in the optical disk. Since the optical disc is manufactured with the same stamper, the track distortion portion of the optical disc can be optimally specified by specifying the manufacturer.
[0016]
The invention according to claim 8 is characterized in that a tracking error signal is generated by calculating a difference between push-pull signals, and an off-track amount is added to the generated tracking signal to perform tracking control during recording. Item 6. The optical recording method according to Item 6, wherein accurate tracking can be performed.
[0017]
Hereinafter, embodiments of the optical disk device of the present invention will be described with reference to FIGS.
[0018]
FIG. 1 is a schematic block diagram showing the configuration of an optical disc apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an optical disc capable of recording information or data by light. The optical disc 1 is provided on at least a substrate, a recording layer provided on a part or the entire surface of the substrate, and on the recording layer. Has protective material. As the optical disc 1, a DVD-R disc, a DVD-RW disc, a DVD-RAM disc, a CD-R disc, a CD-RW disc or the like is preferably used.
[0019]
The optical disc 1 is provided with a spiral groove (not shown) between the inner periphery and the outer periphery, and this groove becomes a track. Data is recorded on this track in units of error correction units, for example, in the form of pits. Further, the outer portion of the track has a meandering shape called a wobble with a constant length period, and is extracted as a clock signal for rotation control, for example. In addition, information and address information of various optical disc manufacturers called LPP are embedded in land portions (protruding portions) between a pair of adjacent tracks, and LPP is also used as a reference signal during recording. .
[0020]
This optical disk 1 is mounted on a spindle motor 4 and is driven to rotate. During recording, CLV rotation control with a constant linear velocity is performed based on a wobble signal period that is a meandering component read by the optical pick 2. At the time of reproduction, rotation control is performed at a constant angular velocity based on CLV control or an FG signal (rotation information from the encoder of the spindle motor 4) which is rotation cycle information of the spindle motor 4. The optical pick 2 is equipped with a light emission source (not shown), and for example, a laser diode is preferably used as the light emission source. The light emitted from the light source is transmitted or reflected by various optical components, and finally the light spot collected by the objective lens 3 is irradiated onto the optical disc 1. Further, the light reflected by the optical disc 1 is transmitted or reflected through various optical components via the objective lens 3, enters a light receiving means (not shown) mounted on the optical pick 2, and enters the light receiving means. The light is converted into an electric signal by a photo detector or the like, and the electric signal is demodulated into data usable by servo control or a computer.
[0021]
The optical pick 2 is attached to a device that is movably attached to a feed mechanism (not shown) so as to be movable between the inner periphery and the outer periphery of the optical disc 1. The objective lens 3 is supported by an actuator (not shown) and can be moved by driving in the tracking and focusing directions.
[0022]
Based on the focus and tracking error signals, the optical spot is controlled by a control means to be described later so that the light spot accurately follows the track with respect to the surface shake and eccentricity component of the optical disk 1.
[0023]
For recording data on the optical disk 1, the optical disk controller 11 receives a recording command and received data corresponding to information to be recorded on the optical disk 1 from the host via the interface 13. The optical disk controller 11 performs 8-16 conversion on the received data and modulates the data to be recorded. Then, the laser driver 5 is driven in accordance with the recording data string to supply current to a light emitting source which is a laser diode mounted on the optical pick 2, and the light emitting source emits pulses by the driving current. The optical disk 1 is irradiated with light through the objective lens 3 through optical components, and data is recorded on the track of the optical disk 1 in the form of pits, for example.
[0024]
On the other hand, data reproduction processing is performed as follows.
[0025]
The light source of the optical pick 2 emits light, and the optical disk 1 is irradiated with light through various optical components and through the objective lens 3. At this time, as a matter of course, the objective lens 3 is irradiated with light that is weaker than the light intensity during recording. Reflected light from the optical disc 1 passes through the objective lens 3 and is taken into the optical pick 2 and enters a light receiving means provided in the optical pick 2 through various optical components. The light incident on the light receiving means is guided to a photodetector which is built in the light receiving means and divided into a plurality of parts. The photodetector divided into a plurality outputs an electrical signal corresponding to the intensity of light and the area to be irradiated. The electric signal is amplified by the head amplifier circuit 6 and current-voltage conversion of the electric signal is performed. The converted electric signal is passed through an RF analog reproduction circuit 9 having an AGC, a filter, an equalizer correction circuit, and the like. After that, the electric signal is transmitted to the optical disc controller 11. Then, the electric signal is binarized in the optical disk controller 11 and converted into a predetermined data string, and the data string is converted into transmission data through decoding means having an 8-16 demodulating circuit and an error correcting circuit, and the transmission is performed. Data is transmitted to the host via the interface 13.
[0026]
Next, servo control using a focus error signal and a tracking error signal will be described.
[0027]
The light source of the optical pick 2 emits light, and the optical disk 1 is irradiated with light through various optical components and through the objective lens 3. Reflected light from the optical disc 1 passes through the objective lens 3 and is taken into the optical pick 2 and enters a light receiving means provided in the optical pick 2 through various optical components. At this time, in this embodiment, the light receiving means uses a push-pull method. The light incident on the light receiving means is guided to a photodetector which is built in the light receiving means and divided into a plurality of parts. The photodetector divided into a plurality outputs an electrical signal corresponding to the intensity of light and the area to be irradiated. The electric signal is amplified by the head amplifier circuit 6, current-voltage conversion of the electric signal is performed, and further, the offset of the circuit is applied to the electric signal subjected to voltage conversion. The signal is sent to the D conversion circuit 8, the electric signal is sampled by the A / D conversion circuit 8, converted into a digital signal, and sent to the DSP 15. The DSP 15 performs arithmetic processing for generating a tracking error signal and a focus error signal based on these digital signals. The tracking or focus error signal is subjected to predetermined processing by a filter and phase compensation processing means provided in the DSP 15 to be converted into a PWM signal having a different pulse width, and the PWM signal as the drive signal is converted into the DSP 15. Is sent to the Act drive circuit 7 to drive at least the objective lens 3 in the tracking and focusing directions, and servo control is performed so that each error signal becomes substantially zero.
[0028]
In this embodiment, the push-pull method is used as the tracking error signal generating means.
[0029]
In the wobble / LPP reproduction circuit 10, the wobble signal and the LPP pulse signal are extracted by the electric signal sent from the head amplifier circuit 6. The LPP pulse signal output from the wobble / LPP reproduction circuit 10 is sent to the optical disk controller 11, and the optical disk controller 11 demodulates the LPP pulse signal and converts it into LPP data. The LPP data is sent to the microcomputer 12, Identify the optimum parameters for recording, disc manufacturer, and disc type. In order to perform recording with higher accuracy, the microcomputer 12 reads various parameters related to recording corresponding to the disk information from the memory 14 and records data. In the optical disc apparatus of the present invention, information such as the manufacturer of the optical disc for a specific optical disc 1, tracking offset correction values defined in advance by predetermined correction profile data corresponding to the disc of the manufacturer, and the tracking thereof. The offset correction timing is stored in the memory 14 in advance, and the tracking correction at the time of recording is performed by the tracking error signal obtained by adding the timing and the tracking offset correction value at the time of recording the specific part. Even at a portion having a track distortion on a specific optical disc, data can be accurately recorded on a desired track without writing data on an adjacent track.
[0030]
Hereinafter, an avoidance processing method at the time of recording with respect to the track distortion which is the gist of the present invention will be described.
[0031]
FIG. 2 shows a state when the light beam S traverses at an angle with respect to the tracks T1 to T4 due to the eccentricity of the optical disk 1 when the tracking control is turned off. At this time, it is assumed that the tracks T2 and T3 are in a poor condition such as a stamper when the optical disc 1 is manufactured, and the tracks are distorted so as to approach each other as shown in FIG. Then, when the light beam S is moved in a trajectory as shown in FIG. 2, a TE signal is detected as shown in FIG. In the present embodiment, the embodiment has been described in which four tracks are crossed for the sake of convenience of explanation. However, the number of crossing tracks is about several tens to one hundred due to the eccentricity when the optical disk 1 is mounted. .
[0032]
A waveform 17 in FIG. 3 shows a tracking error signal straddling a track distortion portion when only the tracking control is removed while the focus control is in the closed state. As shown in FIG. 3, every time a track is crossed, the tracking error signal changes by 2π phase and is repeated. In the track distortion portion, the track pitch is partially denser than the predetermined pitch length (between the track T2 and the track T3), and the adjacent track has a wide track pitch. (Between track T1 and track T2, between track T3 and track T4). Further, it is observed that the amplitude value of the tracking error signal is reduced at the distortion point. Tracking control is performed at the zero-cross point of the tracking error signal that rises to the right. Therefore, in FIG. 3, the tracking control position in the distortion track T3 has a zero cross point below the tracking error signal, and the control is performed by shifting from the original track center (B in FIG. 3) to the outer peripheral side. . On the contrary, the track adjacent to the outer circumference side of the track T2 is controlled on the upper side of the tracking error signal, that is, from the track center (FIG. 3A) toward the inner circumference side. Therefore, the track pitches on both sides of the track distortion portion are coarse. Such a distortion location exists on the optical disk 1 over a plurality of locations. The length of the distorted portion hardly circulates in the track circumferential direction, but is a short section of about a fraction of one round, and is often distorted at substantially the same angular velocity.
[0033]
If a tracking error signal having such a distortion is followed, the track pitch recorded at the track distortion portion will have a coarse track pitch. In FIG. 3, the waveform 18 obtained by extracting the distortion component of the tracking error has a undulation. Therefore, by adding a waveform 19 having a characteristic opposite to that of this component, it is possible to correct the distortion of the tracking error signal and control the track center.
[0034]
As described above, for the optical disc 1 having a problem in stamper molding or the like and having a distortion in the track groove state, the track distortion problem is similarly applied to all the discs regardless of variations in the optical disc manufacturing process or manufacturing lot differences. Will occur. In order for the optical disc apparatus to recognize this specific disc, the disc is identified by reading the manufacturer and disc model number from the Disk ID code identified from the LPP or the like embedded between the tracks of the optical disc 1. The identified optical disk 1 with a poor molding state is subjected to processing different from that of a normal optical disk during recording.
[0035]
The distortion part is a part that induces tracking error distortion. If the distortion component is corrected, there is almost no problem in the recording / reproducing characteristics, and the characteristic is different from that of a normal disk defect.
[0036]
For a disk having track distortion, a correction table 29 for correcting a distortion portion is stored in advance in firmware such as the memory 14 for each disk ID. FIG. 4 shows the configuration of the correction table. It consists of four pieces of information of a distortion part physical address 20 indicating position information of each distortion part, a correction start delay 23 for adjusting the correction timing, a correction amplitude weight 21 and a correction count 22, and in order of increasing distortion part address. Stored as a table. In this embodiment, a physical address is 3 bytes, a correction start delay time is 14 bits, a correction amplitude weight value is 1 bit, and the number of corrections is 1 bit.
[0037]
Next, a basic profile for tracking offset correction will be described with reference to FIG. The waveform in FIG. 5 is obtained by configuring the reverse polarity of the distortion component in a fixed section before and after the tracking distortion location as a tracking correction profile, and dividing the offset value in stages by dividing it into 32 correction step intervals. . Here, − side means offset correction to the inner periphery side of the disc, and + side means offset correction to the outer periphery side of the disc. The physical address information registered in the correction table 29 means the physical address of the ECC block including the maximum correction amount at 26 positions.
[0038]
The time indicated by 25 corresponds to the time axis of one rotation of the disk, and the correction step interval 28 is adjusted in time so that the 26 positions and 27 positions that are corrected to the maximum in both poles are adjacent track positions. . At the time of recording, rotation control is performed so that the linear velocity is constant, so that the time length of one rotation becomes longer as the recorded physical address increases toward the outer peripheral side. Therefore, according to the physical address position of the correction location, the cycle time of one rotation of the disk at that position is calculated, the time correction of the correction step interval 28 is performed, and the entire track offset profile is adjusted on the time axis.
[0039]
The correction start timing is controlled by a correction start delay 23. At the same time as the recording of the address 2 ECC blocks before the registered distortion location physical address 20 is started, the timer is turned on and time measurement is started. When the timer value reaches the correction start delay 23, the track offset correction starts according to the tracking correction profile. Is done. Further, according to the information of the corrected amplitude weight 21, a corresponding constant coefficient is multiplied and the amplitude value of the offset profile is controlled. The value of the correction amplitude weight 21 is increased at a location where the track distortion amount is extremely large. In this embodiment, since 1 bit is weighted, two levels of amplitude values can be selected. In addition, the number of track offset corrections is defined according to the correction number 22. When this information bit is 0, it is defined as one cycle of correction, and when this information bit is 1 is defined as two cycles of correction, the offset profile is continuously repeated. When data is recorded on the optical disc 1, recording is started from a predetermined address position after the data is transferred from the host and modulated. At this time, in the case where data is recorded at the address of the already registered track distortion location, when the correction count is 1, the correction profile is repeated twice.
[0040]
FIG. 6 shows a tracking correction flowchart, and the flow of processing will be described.
[0041]
When the optical disk 1 is mounted on the optical disk apparatus (S1), the optical disk apparatus rotates the optical disk 1, learns the laser power system, and emits a laser with an appropriate reproduction power value. Then, the type of the optical disk 1 is discriminated from the observed values of various parameters, and the type of the optical disk 1 is discriminated, and each balance is set at a predetermined track position so as to be optimal for focus and tracking servo control corresponding to each disk. Learning processing such as adjustment, gain adjustment, and offset adjustment is performed (S2). Further, optimum adjustment is performed on the wobble signal and the LPP signal, and various LPP codes embedded in the LPP are read from the disc, and the manufacturer of the optical disc 1 and the optical disc model number are identified (S3).
[0042]
When a data recording command is received from the host (S4), if the inserted optical disk 1 is an optical disk 1 having a track distortion registered in advance in the optical disk apparatus (S5), a tracking error is caused at the distortion point at the time of data recording. By adding a track offset value of a predetermined profile to the signal, a process for avoiding tracking roughness during recording is performed. When recording is started, it is sequentially compared whether or not the physical address where the data is recorded is an address registered in the correction table (S6). When it reaches 2 ECC before the registered address, the linear velocity is calculated based on the disk rotation period at this position (S7), time correction of the offset profile is performed (S8), and the correction start timing is measured (S9). . Then, a correction level defined by the tracking offset profile is added to the tracking error signal for each step (S10) to correct the tracking offset. Then, continuous data recording is performed while performing tracking correction at the distortion point.
[0043]
Extraction of an address position for registering such a track distortion portion can be performed by measuring an error rate and an RF signal on a recorded disc. First, data is recorded over the entire surface of the disk with a recording power slightly higher than the recording power optimum for the recording quality. By recording with a higher recording power, it is possible to more easily receive cross-erase interference from the outer track in a distorted track having a dense track pitch, and to detect more distorted portions. Then, a decrease in the RF signal or the number of error occurrences is detected, and the maximum error occurrence position is measured from a predetermined ECC block delimiter position.
[0044]
As described above, the data recorded in the distorted portion is recorded at an equal interval of the specified track pitch while avoiding the roughness of the track, and the influence of the cross erase from the adjacent track can be suppressed. Also, the local error rate is not lowered.
[0045]
In the present embodiment, the tracking distortion signal registered in the correction table is subjected to the offset correction of the tracking error signal according to the correction profile, but in a part where there is distortion that disturbs the focus error signal, Needless to say, the focus error signal can be dealt with by performing offset correction.
[0046]
FIG. 7 shows a block diagram of tracking offset correction in the DSP 15. A tracking error signal is generated by the difference between the bipolar push-pull signals TR + and TR− output from the photodetector of the light receiving means (M portion in FIG. 7). When the tracking error signal must be corrected during recording as described above, the microcomputer 12 uses the means represented by the switch WG, for example, to calculate the correction value stored in the memory 14 as described above. The tracking error signal is added to the tracking error signal. As a result, the tracking error signal is corrected and tracking control is performed when the tracking error signal is offset.
[0047]
In the present embodiment, the nonvolatile memory 14 is provided separately, but a memory inside the microcomputer 12 may be used. In addition, two circuits, a wobble extraction circuit and an LPP extraction circuit, may be provided with separate wobble / LPP extraction circuits.
[0048]
【The invention's effect】
The optical disc apparatus of the present invention stores in advance a disc ID information having track distortion, a physical address for specifying a distortion location, and offset start position information in a nonvolatile memory, and a tracking error during recording according to a predetermined track offset profile. It is configured to perform data recording by performing tracking control by adding to the signal, and has an effect of avoiding a coarse and dense recording at a track distortion portion and eliminating a reading error.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing the configuration of an optical disc apparatus according to an embodiment of the present invention.
FIG. 2 is an enlarged view of an optical disc in which a track distortion assumed by the optical disc apparatus according to an embodiment of the present invention has occurred.
FIG. 3 is a waveform diagram of an optical disc apparatus according to an embodiment of the present invention.
FIG. 4 is a diagram showing a correction location information table of the optical disc apparatus according to the embodiment of the present invention.
FIG. 5 is a diagram showing a basic profile of an optical disc apparatus according to an embodiment of the present invention.
FIG. 6 is a flowchart of tracking correction of the optical disc apparatus according to the embodiment of the present invention.
FIG. 7 is a block diagram of tracking offset correction in the DSP 15 of the optical disc apparatus according to the embodiment of the present invention.
[Explanation of symbols]
1 Optical disc
2 Optical pick
3 Objective lens
4 Spindle motor
5 Laser driver
6 Head amplifier circuit
7 Act drive circuit
8 A / D conversion circuit
9 RF analog reproduction circuit
10 Wobble / LPP regeneration circuit
11 Optical disk controller
12 Microcomputer
13 Interface
14 memory
15 DSP

Claims (8)

A recordable / reproducible optical disc apparatus having tracking error extraction means based on a push-pull signal, addition means for adding a tracking offset value, and tracking control means for an optical pick, and a plurality of track distortion points defined in advance by physical addresses Is recorded as table information in a non-volatile memory, and in a recording operation including the distortion portion, a tracking offset is changed and added in a stepwise manner according to a predetermined offset profile to record data. . 2. The registration information of each distortion location has tracking offset correction start position information measured from two ECC blocks before, and adjusts the timing of track offset addition based on the start position information. The optical disk device described. 2. The optical disk apparatus according to claim 1, wherein the offset profile of the stepwise tracking offset has a length of at least one period of the disk, and the polarity of the offset is reversed at a position sandwiching the distortion portion. 2. The optical disc apparatus according to claim 1, wherein the registration information of each distortion location includes tracking offset amplitude weight information, and an offset profile is multiplied and added based on the weight information based on the weight information. 2. The optical disc apparatus according to claim 1, wherein the registration information of each distortion location has a correction count information bit, and correction is performed by repeating an offset profile a plurality of times according to the correction count information bit. By reading the information of a predetermined part of the optical disc, the type of the optical disc is specified, it is determined whether or not the optical disc is stored in the storage means, and in the case of the optical disc stored in the storage means, a track is recorded on the optical disc. A portion where distortion has occurred is read out from the storage means, and an off-track amount specific to the track distortion portion is read out from the storage means, and tracking is performed in consideration of the off-track amount when recording the track distortion portion. Performing an optical recording method. 7. The optical recording method according to claim 6, wherein the optical disc is specified by information corresponding to a manufacturer stored in the optical disc. 7. The optical recording method according to claim 6, wherein a tracking error signal is generated by calculating a difference between push-pull signals, and an off-track amount is added to the generated tracking signal to perform tracking control during recording.

Images