JP4403385B2 - Recording apparatus and recording method - Google Patents

Description

  The present invention relates to a recording apparatus and a recording method for a disk recording medium, and more particularly to laser power control and skew adjustment during a recording operation.

Japanese Patent No. 2764965 JP-A-4-10237 JP-A-6-76288 JP 2000-331364 A Japanese Patent Laid-Open No. 2001-184589

Recording / reproducing apparatuses using an optical disc as a recording medium are widely used. As the optical disc, a reproduction-only disc, a write-once disc, a rewritable disc, or the like is used.
The read-only disk is a so-called ROM type disk in which information recording is performed by, for example, embossed pits.
A write-once disk is a disk on which information is recorded by using a dye-changing film as a recording layer and forming dye-changing pits (marks) with laser light, and can be written only once.
A rewritable disc is a disc on which information is recorded by using a phase change film as a recording layer and forming phase change pits (marks) by laser light, and can be rewritten.
These various discs are used for various purposes according to their characteristics.

Incidentally, in a recording apparatus for a write-once disc or a rewritable disc, it is effective to perform laser power control during a recording operation. This technique is known as so-called running OPC (Oputimum Power Control).
In particular, running OPC is effective for disk manufacturing unevenness (recording film unevenness), skew (optical axis and disk tilt), and the like. For example, the shape of the laser spot and the energy distribution within the spot fluctuate due to manufacturing film irregularities and skew conditions during recording, and the pit formation capability fluctuates, so the laser power is adjusted during recording accordingly. It is preferable to maintain the pit formation capability.
The above Patent Documents 1, 2, and 3 disclose the technique of running OPC.

In addition, a skew (tilt) occurs between the laser optical axis and the disk by the optical head due to the warpage of the disk, but coma aberration occurs when the optical disk is tilted in the radial direction with respect to the laser optical axis. Jitter becomes large and playback becomes difficult. In particular, when the laser wavelength is shortened and the optical system is increased in NA as the disk density is increased, the margin of inclination of the laser optical axis with respect to the recording surface of the disk is reduced, and skew adjustment is accordingly performed. Increased importance.
For this reason, a skew adjustment mechanism is provided to adjust the inclination of the optical head (optical pickup), and various techniques relating to skew adjustment have been proposed as seen in Patent Documents 4 and 5.

As a mechanism for adjusting the skew, a system in which the pickup is mechanically tilted to match the disk tilt, a system in which only the objective lens is tilted to correct coma aberration, and a liquid crystal correction plate is inserted in the optical path in the pickup and so on.
In addition, the control method includes a method for controlling the jitter of the reproduced RF signal to be minimized, a method for maximizing the amplitude of the RF signal, and a push-pull signal when the tracking servo is not applied. There are ways to maximize the amplitude. In addition, there is a method of detecting the tilt of the disc using an external sensor, but this is not applied except for a correction method in which the pickup is usually mechanically tilted.

By the way, all of the above methods for skew control are effective at the time of reproduction, but control other than the method using an external sensor cannot be performed at any time during recording. Also, using an external sensor increases the cost and mechanical burden.
Therefore, the tilt control at the time of recording is a normal method in which the tilt of each part of the disc is examined by a method used at the time of reproduction before recording and is corrected along the profile at the time of recording. The problems with this method are that it cannot be handled when the optimum tilt point during playback differs from the optimum tilt point during recording, it takes extra time to check the tilt before recording, and it takes time to increase the number of measurement points. For example, it is very difficult to increase the number of measurement points.

On the other hand, as described in Patent Documents 4 and 5, it is known to perform skew adjustment based on an RF signal obtained during recording. That is, skew control is performed based on a signal called a pit level obtained by sampling and holding an RF signal being recorded. Basically, the reproduction RF signal at the time of recording is a signal that has a waveform corresponding to the recording laser, but utilizes the fact that the amount of reflected light decreases as the pits are properly formed. The skew control is performed so that the signal level of the pit level becomes small.
By this control method, the above problem can be solved by performing skew control at any time during recording.

However, as shown in Patent Documents 1, 2, and 3, also in the running OPC performed during recording, power control is performed using a signal called a pit level obtained by sampling and holding an RF signal as an error signal.
Then, during recording, the RF signal is used as an error signal for both skew adjustment and running OPC. However, since the skew state and the laser power affect each other, it is difficult to execute skew adjustment and running OPC at the same time. It is. Basically, when performing skew adjustment, the running OPC must be stopped and the laser power must be fixed. The running OPC is preferably performed in a state after the skew adjustment.
For this reason, it is demanded that the two controls of the running OPC and the skew adjustment can be reasonably executed without interfering with each other.

  Accordingly, an object of the present invention is to optimize the interval at which running OPC and skew adjustment are alternately performed during a recording operation so that these function properly and improve the recording / reproducing performance.

For this reason, the recording apparatus of the present invention is obtained by sampling the recording head means for recording information by irradiating the disk recording medium with laser light and the return light of the laser light irradiated on the disk recording medium. Based on the evaluation signal, the laser power control means for variably controlling the power of the laser light output from the recording head means, and the evaluation signal obtained by sampling the return light of the laser light applied to the disk recording medium . A skew driving unit that adjusts an inclination of the optical axis of the laser beam with respect to the disk recording medium so that a change rate is equal to or less than a predetermined value, and a laser that is applied to the disk recording medium while driving and controlling the skew driving unit An evaluation signal obtained by sampling the return light of the light is detected, and the inclination of the optical axis of the laser beam with respect to the disk recording medium is adjusted. During the recording operation by the cue control means and the recording head means, the processing of the skew control means is executed at a constant time interval or a constant address interval, and the laser power control is performed during the fixed time or constant address interval. Execution control means for executing the processing of the means.

The recording method of the present invention includes a laser power control step for variably controlling the power of the laser light based on an evaluation signal obtained by sampling the return light of the laser light irradiated on the disk recording medium, and the disk recording medium while changing the inclination of the optical axis of the laser beam with respect to, the laser beam of the return light irradiated on the disc recording medium to detect an evaluation signal obtained by sampling, the change rate of the evaluation signal is given below As described above, a skew control step of adjusting the inclination of the optical axis of the laser beam with respect to the disk recording medium is performed during the recording operation with respect to the disk recording medium. Then, during the recording operation, the process of the skew control step is executed at a constant time interval or a constant address interval, and the laser power control step is executed during the fixed time or constant address interval.

The state of warping of the disk differs depending on the inner / outer periphery of the disk, and the skew state changes depending on the radial position. In particular, the degree of warpage increases as it goes to the outer peripheral side.
In the present invention, during a recording operation, skew adjustment is performed every time a certain time elapses or every time a recording operation progresses a certain address interval. As seen, the closer to the outer periphery of the disk, the closer the gap as the radial position where skew adjustment is performed.

In the present invention, since skew control is performed based on the RF signal during recording, it is possible to set an optimum inclination for recording, and it is possible to adjust skew at any time during the recording operation. In this case, laser power control (running OPC) during the recording operation is also performed based on the RF signal during recording, but this skew adjustment and running OPC are performed rationally alternately.
The skew adjustment is performed every time a certain time elapses or every time the recording operation progresses a certain address section during the recording operation. Therefore, when viewed from the radial position of the disk, the skew adjustment is performed. The interval as the radial position where the skew adjustment is performed is narrowed. Since the degree of warping of the disk increases as it goes to the outer peripheral side, and it is preferable to increase the frequency of skew adjustment toward the outer peripheral side, the radial position where skew adjustment is performed as it goes to the outer peripheral side of the disk as described above It is a reasonable and appropriate execution control method to narrow the interval between and close.
Since the skew adjustment is performed at a constant time interval or at a constant address interval, the running OPC is a period during which the skew adjustment is performed (that is, during the progress of the fixed time or the progress of the fixed address interval). To be done.
That is, in the present invention, the running OPC functions as much as possible during the recording operation, and the skew adjustment is performed at an appropriate timing, thereby improving the recording operation performance.

Hereinafter, for example, a recording / reproducing apparatus (disk drive apparatus) capable of writing data to a CD-type or DVD-type write-once disk or rewritable disk will be described as an example, and the embodiments will be described in the following order.
1. 1. Configuration of disk drive device according to embodiment Triaxial mechanism3. Running OPC and skew control processing

1. Configuration of the disk drive device of the embodiment

FIG. 1 shows the configuration of the disk drive apparatus according to the embodiment. The present invention is characterized by the running OPC and the skew adjustment method, and various configurations therefor will be described later as the first to third embodiments. In FIG. 1, the first to third embodiments described later are used. The overall configuration of the disk drive device is shown, including the configuration change for each of the forms.

The disk 1 is assumed to be a write-once type disk known as, for example, DVD-R, DVD + R, DVD ± R or the like. Normally, a disk drive device can record and reproduce not only a write-once disk but also a reproduction-only disk or a rewritable disk, so that the disk 1 is not limited to a write-once disk.
The disk 1 is loaded on a turntable (not shown) and is driven to rotate at a constant linear velocity (CLV) by the spindle motor 2 during the recording / reproducing operation. The pickup (optical head) 3 reads data recorded on the disk 1 with a constant linear density in an emboss pit form, a dye change pit form, or a phase change pit form. In addition, not only CLV at the time of reproduction | regeneration but it can also be rotationally driven by a fixed angular velocity (CAV).

In the pickup 3, as will be described later, a laser diode serving as a laser light source, a photodetector for detecting reflected light, an objective lens serving as an output end of the laser light, and irradiating the disk recording surface with the laser light through the objective lens In addition, an optical system for guiding the reflected light to the photodetector, a triaxial mechanism, and the like are provided. The triaxial mechanism is a mechanism that holds the objective lens so as to be movable in the tracking direction, the focus direction, and the skew control direction.
Further, the entire pickup 3 can be moved in the radial direction of the disk by the slide drive unit 4.

Reflected light information from the disk 1 is detected by a photo detector, converted into an electric signal corresponding to the amount of received light, and supplied to the RF amplifier 8.
The RF amplifier 8 includes a current-voltage conversion circuit, a matrix calculation / amplification circuit, and the like corresponding to output currents from a plurality of photodetectors in the pickup 3, and generates necessary signals by matrix calculation processing. For example, an RF signal as reproduction data, a focus error signal FE for servo control, a tracking error signal TE, and the like are generated.
The reproduction RF signal output from the RF amplifier 8 is supplied to the reproduction signal processing unit 9, and the focus error signal FE and the tracking error signal TE are supplied to the servo control unit 10.

The reproduction RF signal obtained by the RF amplifier 8 is subjected to binarization, PLL clock generation, decoding processing for the EFM + signal (8-16 modulation signal), error correction processing, and the like in the reproduction signal processing unit 9.
The reproduction signal processing unit 9 performs decoding processing and error correction processing using the DRAM 11. The DRAM 11 is also used as a cache for storing data obtained from the host interface 13 and transferring data to the host computer.
Then, the reproduction signal processing unit 9 accumulates the decoded data in the DRAM 11 as a cache memory.
As the reproduction output from the disk drive device, the data buffered in the DRAM 11 is read and transferred and output.

The reproduction signal processing unit 9 extracts subcode information, ATIP information, LPP information, ADIP information, sector ID information, and the like from information obtained by EFM + demodulation and error correction for the RF signal. Is supplied to the system controller 12.
The system controller 12 is formed by a microcomputer, for example, and controls the entire apparatus.

The host interface 13 is connected to a host device such as an external personal computer, and communicates reproduction data and read / write commands with the host device.
That is, the reproduction data stored in the DRAM 11 is transferred and output to the host device via the host interface 13.
Read / write commands, recording data, and other signals from the host device are buffered in the DRAM 11 or supplied to the system controller 12 via the host interface 13.

Recording to the disk 1 is performed by supplying a write command and recording data from the host device.
At the time of data recording, the recording data buffered in the DRAM 11 is subjected to processing for recording in the modulation unit 14. That is, processing such as error correction code addition and EFM + modulation is performed.
The recording data WD modulated in this way is supplied to the laser modulation circuit 15. The laser modulation circuit 15 drives the semiconductor laser in the pickup 3 according to the recording data, executes laser output according to the recording data, and writes data to the disk 1.

During this recording operation, the system controller 12 is controlled to irradiate the recording area of the disc 1 with laser light from the pickup 3 with recording power.
When the disk 1 is of a write-once type using a dye change film as a recording layer, pits due to dye change are formed by laser irradiation of recording power.
When the disk 1 is a rewritable disk having a phase change recording layer, the crystal structure of the recording layer is changed by heating the laser beam, and phase change pits are formed. That is, various data are recorded by changing the presence and length of pits. Further, when the portion where the pits are formed is irradiated again with laser light, the crystal state changed at the time of data recording is restored to the original state by heating, the pits disappear and the data is deleted.

The servo control unit 10 receives various focus, tracking, slide, and spindle servos from the focus error signal FE and tracking error signal TE from the RF amplifier 8 and the spindle error signal SPE from the reproduction signal processing unit 9 or the system controller 12. Generate drive signal and execute servo operation.
That is, a focus drive signal and a tracking drive signal are generated according to the focus error signal FE and the tracking error signal TE, and supplied to the focus / tracking drive circuit 6. The focus / tracking drive circuit 6 drives the focus coil and tracking coil of the triaxial mechanism in the pickup 3. As a result, the pickup 3, the RF amplifier 8, the servo control unit 10, the focus / tracking drive circuit 6, the tracking servo loop and the focus servo loop by the triaxial mechanism are formed.

  The servo control unit 10 further supplies a spindle drive signal generated according to the spindle error signal SPE to the spindle motor drive circuit 7. The spindle motor drive circuit 7 applies, for example, a three-phase drive signal to the spindle motor 2 according to the spindle drive signal, and causes the spindle motor 2 to rotate. The servo control unit 10 also generates a spindle drive signal in response to a spindle kick / brake control signal from the system controller 12, and causes the spindle motor drive circuit 7 to perform operations such as starting, stopping, accelerating and decelerating the spindle motor 2. .

  The servo control unit 10 generates a slide drive signal based on, for example, a slide error signal obtained as a low frequency component of the tracking error signal TE, an access execution control from the system controller 12, and supplies the slide drive signal to the slide drive circuit 5. . The slide drive circuit 5 drives the slide drive unit 4 according to the slide drive signal. Although not shown in the figure, the slide drive unit 4 has a mechanism including a main shaft that holds the pickup 3, a thread motor, a transmission gear, and the like, and the slide drive circuit 5 drives the slide drive unit 4 in response to a slide drive signal. The required slide movement of the pickup 3 is performed.

The sample / hold circuit 16 is supplied with an RF signal from the RF amplifier 8. The sample / hold circuit 16 samples the return light (RF signal) at a timing based on the sample pulse Ps particularly for running OPC and skew adjustment during recording.
The sample pulse Ps is generated by the timing generator 19. The timing generator 19 sets a sample timing based on the data string as recording data generated by the modulation unit 14.
The signal sampled by the sample / hold circuit 16 is converted into digital data by the A / D converter 17 and supplied to the system controller 12 as information on a predetermined timing in the RF signal, that is, light amount data PL of the return light.
The return light at the time of recording is naturally not based on the reproduction data from the already recorded pits, but is basically a signal corresponding to the output laser light, and is similar to the waveform of the laser drive signal. It becomes a waveform. The amount of the return light fluctuates due to the influence of pits formed on the recording layer of the disk 1 as a recording operation. If the pits are formed properly, the amount of return light decreases, but the amount of return light increases as the pits cannot be formed properly due to the influence of skew and recording film manufacturing unevenness. Therefore, the level of the return light during recording is an index for running OPC and skew adjustment.

The system controller 12 performs running OPC control and skew adjustment control during the recording operation.
For example, the system controller 12 controls the laser modulation circuit 15 according to the supplied return light level (light quantity data PL), and performs an operation of variably controlling the laser power during recording. Specifically, the system controller 12 gives the target value of the laser power to the laser modulation circuit 15 and instructs the laser output level to be the target value.

The skew drive circuit 19 controls the inclination of the objective lens by adjusting the inclination of the laser optical axis and the disk surface by applying a current to the tilt coil of the triaxial mechanism in the pickup 3.
The skew drive circuit 19 performs skew drive under the control of the system controller 12.
The system controller 12 outputs a drive control signal for skew drive, and the drive control signal is converted to an analog voltage (skew drive voltage) by the D / A converter 18 and supplied to the skew drive circuit 19. The skew drive circuit 19 drives the triaxial mechanism based on the applied skew drive voltage.
The system controller 12 monitors the light quantity data PL while executing skew driving in this way, and determines the optimum skew state.

In this example, the system controller 12 performs the running OPC control and the skew control. However, in addition to the system controller 12, an OPC controller that performs the running OPC control and a skew controller that performs the skew control may be provided. .

2. Triaxial mechanism

In this example, a triaxial mechanism is mounted in the pickup 3 for skew adjustment. The triaxial mechanism is a mechanism that can move the objective lens in the tracking direction and the focus direction and tilt it in the skew control direction, and an example of this will be described with reference to FIGS.

As shown in FIGS. 2 and 3, the triaxial mechanism 36 includes a base member 109, a fixed block 110, and a movable block 111 that is operated with respect to the fixed block 110.
Each part of the base member 109 is integrally formed of a magnetic metal material. The base part 109a, the first yoke parts 109b and 109b that are bent at right angles from the base part 109a, and the base member 109a are bent at right angles. Second yoke portions 109c and 109c. The first yoke portions 109b and 109b are spaced apart in the front-rear direction, that is, the direction orthogonal to both the focusing direction and the tracking direction, and the second yoke portions 109c and 109c are separated in the left-right direction, that is, the tracking direction. Are arranged. Magnets 112, 112 each having a horizontally long rectangular shape are attached to the surfaces of the first yoke portions 109 b, 109 b facing each other.

The fixed block 110 has three spring mounting portions 110a, 110a,... A circuit board (not shown) is attached to the fixed block 110.
.. Are attached to the spring mounting portions 110a, 110a,... Of the fixed block 110 on the left and right, respectively, and the support springs 113, 113,. One end of each is connected to a circuit board attached to the fixed block 110. A drive current is supplied to the support springs 113, 113,... Via the circuit board.

The movable block 111 has a bobbin 114, and insertion cylinders 114a and 114a are provided at both left and right ends of the bobbin 114, respectively. The insertion tube portions 114a and 114a are formed in a substantially rectangular tube shape penetrating vertically.
A focusing coil 115, tracking coils 116, 116,... And tilt coils 117, 117 are attached to the bobbin 114.
The focusing coil 115 is formed in a substantially rectangular tube shape with a horizontally long thickness so that the axial direction is the vertical direction, and is wound around the outer peripheral surface of the bobbin 114.
The tracking coils 116, 116,... Are formed in a substantially rectangular tube shape with a thin thickness so that the axial direction is the front-rear direction, and two tracking coils are disposed at positions facing the left and right ends of the magnets 112, 112 respectively. It is attached.
The tilt coils 117 and 117 are formed so that the axial direction is the front-rear direction, and are attached at positions facing the front and rear magnets 112 and 112 of the bobbin 114 as shown in FIG. 2 and 3, the tilt coils 117 and 117 are positioned between the tracking coils 116, 116,.

As shown in FIG. 4, the tilt coil 117 includes, for example, oblique sides 117a and 117a inclined by about 45 ° with respect to the focusing direction and the tracking direction, and a horizontal extending continuously from the oblique sides 117a and 117a to the left and right. It is composed of parts 117b and 117b, and vertical parts 117c and 117c which are positioned between the horizontal parts 117b and 117b and the oblique sides 117a and 117a and extend vertically. The oblique sides 117a and 117a, the horizontal portions 117b and 117b, and the vertical portions 117c and 117c are formed in parallel to each other.
The tilt coils 117 and 117 are attached to both front and rear surfaces of the bobbin 114 with the oblique sides 117a, 117a,... Extending in the same direction.
In addition, the tilt coil 17 is positioned so as to face the portions excluding the left and right ends of the magnet 112, and the oblique sides 117a and 117a are positioned substantially corresponding to the central portion where the magnetic flux density of the magnet 112 is high. The portions 117b and 117b are positioned corresponding to the upper and lower ends of the magnet 112 where the magnetic flux density is low, and the vertical portions 117c and 117c are positioned corresponding to the upper and lower ends of the magnet 112.
When a current is supplied to the tilt coils 117 and 117, the movable block 111 is moved in a tilt direction (skew control direction) that is a direction around an axis (tilt drive axis) that is orthogonal to both the focusing direction and the tracking direction. .

An objective lens 35 is attached and held at the upper end of the bobbin 114.
Support substrates 119 and 119 are attached to the left and right side surfaces of the bobbin 114, and the other ends of the support springs 113, 113,... Are attached to the support substrates 119 and 119, respectively. Therefore, the movable block 111 is connected to the fixed block 110 by the support springs 113, 113,... And is held in a hollow space between the magnets 112 and 112 attached to the first yoke portions 109 b and 109 b of the base member 109. Be positioned. The second yoke portions 109c and 109c are inserted into the insertion tube portions 114a and 114a of the bobbin 114, respectively.

At this time, the neutral position of the movable block 111 in the focusing direction (vertical direction), that is, the position in a state where the focusing operation is not performed, is performed in the vertical direction of the oblique sides 117a and 117a of the focusing coil 115 and the tilt coils 117 and 117. The central portion is positioned corresponding to the central portion in the vertical direction of the magnets 112 and 112. The central part in the vertical direction of the magnets 112 and 112 is the part with the highest magnetic flux density.
The second yoke portions 109c and 109c are positioned between the left end portions or the right end portions of the magnets 112 and 112, respectively. Therefore, in the triaxial mechanism 36, the magnetic flux density is also increased at the left and right ends of the magnets 112, 112.

The focusing coil 115, the tracking coils 116, 116,... And the tilt coils 117, 117 are respectively connected via the circuit board, the support springs 113, 113,. Drive current is supplied.
When a driving current is supplied to the focusing coil 115, a thrust in a predetermined direction is generated according to the direction of the driving current flowing in the focusing coil 115, and the movable block 111 is shown in FIG. It is moved in the F direction, that is, the focusing direction, which is the direction in which the recording surface of the disk 1 is moved away from or contacting the recording surface.
When a drive current is supplied to the tracking coils 116, 116,..., Thrust in a predetermined direction is generated according to the direction of the drive current flowing through the tracking coils 116, 116,. Are moved in the TT direction shown in FIG. 4, that is, the tracking direction which is the radial direction of the disk 1 with respect to the fixed block 110.
When a drive current is supplied to the tilt coils 117 and 117, thrust in a predetermined direction is generated according to the direction of the drive current flowing through the tilt coils 117 and 117, and the movable block 111 is shown in FIG. 4 is operated in the tilt direction, which is the direction around the axis of the tilt drive axis that is orthogonal to the focusing direction and the tracking direction.
When the movable block 11 is moved in the focusing direction, tracking direction, or tilt direction, the support springs 113, 113,... Are elastically deformed.

If the pickup 3 is provided with the triaxial mechanism 36 configured as described above, the inclination of the objective lens 35, that is, the inclination of the laser optical axis is changed by applying a current to the tilt coil 117 by the skew driving circuit 19. The skew adjustment operation is realized by appropriately adjusting the inclination.
With such a skew adjustment mechanism, for example, a conventional relatively large skew adjustment mechanism such as tilting the entire pickup 3 becomes unnecessary, and the mechanical configuration around the pickup 3 is simplified.

3. Running OPC and skew control processing

FIG. 5 shows a configuration in which only the running OPC and the skew control system are extracted from the configuration of the disk drive device of FIG.
FIG. 5 shows a schematic configuration in the pickup 3. As briefly described above, the pickup 3 includes a laser diode 31 serving as a laser light source, a photodetector 33 for detecting reflected light, and an output of the laser light. The objective lens 35 at the end, the laser beam is irradiated onto the disk recording surface via the objective lens 35, and the reflected light is guided to the photodetector 33. The three-axis mechanism 36 having the above-described structure that supports the objective lens 35 is supported. Is provided.
The optical system 32 is provided with a polarizing element such as a polarizing beam splitter and various lenses, and the optical path of the laser light from the laser diode 31 and the return light reflected on the disk 1 is controlled.
When the disk 1 as a write-once disk is loaded and recording is performed, the laser light output from the laser diode 31 is irradiated onto the recording surface of the disk 1 via the optical system 32 and the objective lens 35, and the recording surface is recorded. Pits (pigment change pits) are formed. At this time, return light reflected on the recording surface can be obtained. However, as the pits are properly formed, the amount of return light decreases.

The return light from the disk 1 enters the photodetector 33 through the objective lens 35 and the optical system 32, undergoes photoelectric conversion, and is supplied to the RF amplifier 8.
As described above, the RF amplifier 8 performs arithmetic processing on the signal from the photodetector 33 to generate an RF signal, a focus error signal, a tracking error signal, and the like, which are sum signals of light amounts. The RF signal (light quantity sum signal) obtained by the RF amplifier 8 is supplied to the sample / hold circuit 16. The sample / hold circuit 16 samples the RF signal at the timing based on the sample pulse Ps from the timing generator 19 as described above, and the sampled signal is returned to the return light via the A / D converter 17. It is supplied to the system controller 12 as level information (light quantity data PL).

  A monitor detector 34 is further provided in the pickup 3 for APC (Auto Power Control). A part of the laser light from the laser diode 31 is supplied to the monitor detector 34 via the optical system 32, for example. The monitor detector 34 then outputs an electrical signal corresponding to the amount of received light. That is, information on the amount of output laser light is obtained by the monitor detector 34.

The laser modulation circuit 15 is provided with a laser driver 41, a write strategy 42, an APC circuit 43, and a register 44.
The recording data WD supplied from the modulation unit 14 of FIG. 1 is converted into a laser drive pulse through waveform shaping and compensation processing in the write strategy 42 and supplied to the laser driver 41. The laser driver 41 drives the laser diode 31 with a laser driving pulse to cause laser emission.
Here, the APC circuit 43 functions to keep the laser output level constant. The APC circuit 43 obtains output laser light level information from the monitor detector 34. The register 44 is set with a target value LT of the laser light level.
The APC circuit 43 takes the difference between the target value LT stored in the register 44 and the information of the output laser beam level by the monitor detector 34, and increases or decreases the drive current from the laser driver 41 according to the difference, thereby increasing the laser current. The laser light level from the diode 31 is controlled to be maintained at the target value LT. This is the APC function.

On the other hand, the system controller 12 performs running OPC control to increase or decrease the laser light level from the laser diode 31 during the recording operation. This is because, as described above, the laser beam level is controlled in accordance with the warp of the disk 1 and the unevenness of the recording film, so that precise pit formation is performed.
The system controller 12 monitors the light amount data PL from the sample / hold circuit 16 and the A / D converter 17 and variably sets the target value LT according to the increase / decrease. That is, when the return light level is determined to be high based on the light amount data PL, the pit formation capability is reduced, and therefore the target value LT is increased so as to increase the laser light level. On the contrary, when the return light level is determined to be low by the light quantity data PL, the pit formation capability is more than sufficient, but it is not appropriate that the laser level is too high. The target value LT is lowered so as to decrease.
Since the APC circuit 43 has a function of converging the laser light level to the target value LT, the system controller 12 rewrites the target value LT of the register 44, whereby the output laser power from the laser diode 31 is varied. .
As the running OPC function, such an operation is continuously performed during the recording operation, so that data writing at an optimum laser level is performed in accordance with the unevenness of the recording film of the disk 1 and the skew situation. .

Further, the system controller 12 performs skew adjustment at a predetermined timing during recording. The system controller 12 monitors the light quantity data PL supplied from the sample / hold circuit 16 and the A / D converter 17 as the evaluation value for the skew adjustment as in the running OPC.
When performing skew adjustment, a drive voltage is supplied to the skew drive circuit 19 to change the current applied to the tilt coil 117 of the triaxial mechanism 36. Then, while changing the drive voltage, the light quantity data PL, which is the skew evaluation value, is monitored to determine the optimum drive voltage. That is, adjustment is performed to obtain an optimal skew state.
FIG. 6 shows the concept of the skew adjustment operation. The horizontal axis indicates the drive voltage, and the vertical axis indicates the amount of return light. In the optimal skew state, the return light level is minimum.
For example, when the driving voltage Vdx is at a certain point, it is detected that the return light level increases from the light amount data PL when the driving voltage is increased. On the other hand, when the drive voltage is lowered, it is detected from the light amount data PL that the return light level decreases. In this case, the system controller 12 controls the drive voltage to decrease, and searches for a drive voltage that minimizes the return light level, for example, as indicated by the drive voltage Vdy.

  Note that the return light level fluctuates not only due to the skew state but also due to recording film unevenness. Therefore, the skew state cannot be detected only by the light quantity data PL. For this reason, the skew controller 18 operates to vary the drive voltage up and down to obtain the light amount data PL in each state and adjust the offset voltage in the direction in which the value of the light amount data PL decreases. .

By the way, the light amount data PL is used as an evaluation value for both the running OPC and the skew adjustment, but the sample / hold circuit 16 samples the RF signal at the timing of the erase level of the laser.
FIG. 7A shows a pit mark row formed by laser emission based on the recording data WD on the track TK of the disk 1, and FIG. 7B shows the return light at that time. The return light in FIG. 7B has the same waveform as the laser emission drive pulse. That is, the laser output appears as return light as it is.
As shown in FIG. 7A, the pit mark PM is formed on the track by laser emission (pulse emission) of recording power, and the laser output is set to the erase level, so that the section ER where no pit mark exists is formed. It is formed.
Then, the sample / hold circuit 16 samples the return light obtained as an RF signal in FIG. 7B, but in this example, the timing generator 19 has an erase level as shown in FIG. The sample pulse Ps is generated so that the sample timing is performed during the period.
The RF signal waveform in FIG. 7B is the same as the laser drive waveform, and the pit mark / erase period is determined by the recording data WD. Therefore, the timing generator 19 is based on the data string of the recording data WD. Thus, the sample pulse Ps defining the sample timing as the erase period is generated.

  During the period in which the pit mark PM is formed, the laser diode 31 emits pulses (intermittent light emission). On the other hand, during the erase period ER, continuous light emission at the erase level is performed. The sample / hold circuit 16 obtains light amount data PL which is an index for running OPC and skew adjustment. Even if it is return light amount information during the period of forming the pit mark PM, it is also returned light amount information during the erase level period. However, in any case, it is preferable that the light amount data PL as the evaluation value is the sample data of the erase level because the level fluctuation caused by the pulse drive does not ride as noise particularly during the erase level period. Become.

Hereinafter, control of the system controller 12 for running OPC and skew adjustment during recording will be described.
FIG. 8 shows execution control processing for executing skew adjustment and running OPC control alternately at appropriate timings during the recording operation.

  In step F1, it is assumed that recording starts from a certain address A0 of the disk 1. The system controller 12 modulates the data supplied from the host device by the modulation unit 14 and starts control to supply the recording data WD to the laser modulation circuit 15. Further, the servo controller 10 is instructed to execute rotation driving of the spindle motor, access to the address A0 of the optical pickup 3, and the like to execute recording from the address A0.

Here, the system controller 12 stores the address A0 in a variable (register) a in step F2 for skew adjustment and running OPC.
In step F3, skew adjustment processing is performed. At this time, the OPC process is stopped, and therefore the laser power is fixed at a certain target value LT.

The skew adjustment process in step F3 is performed as shown in FIG. 9, for example.
The system controller 12 generates a skew drive voltage Vd as an initial value at the start of recording, and supplies the skew drive voltage Vd to the skew drive circuit 19 via the D / A converter 18. It is said that. For example, this initial value is determined to correspond to the tilt neutral position of the objective lens 35 at the time of manufacturing the disk drive device, and is set to, for example, a state of zero tilt.
In step F31, the light quantity data PL obtained through the sample / hold circuit 16 and the A / D converter 17 in the current tilt state of the objective lens 35 is captured, and the light quantity data PL is stored as the evaluation value D0.

Subsequently, in step F32, a voltage obtained by adding the minute voltage ΔVd to the drive voltage Vd (for example, the drive voltage as an initial value) is output as the drive voltage. Accordingly, the objective lens 35 is slightly tilted in the skew + direction of FIG. 6 (for example, the R1 direction of FIG. 4).
In step F33, the light quantity data PL obtained through the sample / hold circuit 16 and the A / D converter 17 is fetched, and the light quantity data PL is stored as an evaluation value D1.

Further, in step F34, the system controller 12 outputs a drive voltage obtained by subtracting the minute voltage ΔVd from the skew drive voltage Vd (for example, the drive voltage as an initial value). Accordingly, the objective lens 35 is slightly tilted in the skew direction of FIG. 6 (for example, the R2 direction of FIG. 4).
In step F35, the light quantity data PL obtained via the sample / hold circuit 16 and the A / D converter 17 is fetched, and the light quantity data PL is stored as an evaluation value D2.

In step F36, the stored three evaluation values D0, D1, and D2 are compared.
Here, if the comparison result is the state (i), that is, D1 <D0 <D2, the light amount data PL is minimized when the drive voltage is increased in step F32, that is, the drive voltage is increased. It can be determined that the direction is approaching an appropriate skew state. Therefore, in this case, the process proceeds to step F38, and the drive voltage Vd is changed to Vd + ΔVd. Then, the process returns to Step F31.
After step F31, the above process is repeated from the changed driving voltage Vd.

If the comparison result is state (ii) in step F36, that is, D2 <D0 <D1, the light amount data PL is minimum when the drive voltage is lowered in step F34. It can be determined that the lowering direction is approaching an appropriate skew state. Therefore, in this case, the process proceeds to Step F37, and the drive voltage Vd is changed to Vd−ΔVd. Then, the process returns to Step F31.
After step F31, the above process is repeated from the changed driving voltage Vd.
If none of the states (i) and (ii) is obtained in step F36, the process directly returns to step F31.

For example, when this process is repeatedly executed, the drive voltage Vd is converged to the drive voltage Vdy that minimizes the amount of return light shown in FIG.
Accordingly, for example, the processing of FIG. 9 is performed for a certain period of time, or the processing of FIG. 9 is performed until some of the states (i) and (ii) are not obtained in step F36. By doing so, skew adjustment is performed.

This process can be said to be a process of adjusting the inclination of the optical axis of the laser light so that the evaluation value (light quantity data PL) obtained by sampling the return light is minimized. However, it is difficult to search for the minimum value accurately, and it takes some time.
Therefore, a method of adjusting the inclination of the optical axis so that the change rate of the evaluation value (light quantity data PL) is equal to or less than a predetermined value by changing the process of step F36 can be considered.
In that case, the condition of the state (i) may be (D1 + α) <(D0 + α) <D2, and the condition of the state (ii) may be (D2 + α) <(D0 + α) <D1. That is, the dead zone of control is set to some extent according to the value of α.

  As described above, for example, the processing of FIG. 9 is performed for a certain period of time, and after step F3 of FIG. The OPC process of step F4 is shown in FIG.

  Note that the initial value as the target value LT of the laser power is set in the register 44 at the start of recording. For example, the system controller 12 sets an initial target value based on the disc type detected when the disc 1 is loaded and the management information read from the disc 1 and stores the initial target value in the register 44.

When the OPC process of FIG. 10 is started in step F4 of FIG. 4, the system controller 12 first acquires the return light level in step F41. That is, the system controller 12 takes in the light amount data PL obtained from the sample / hold circuit 16 and the A / D converter 17.
In step F42, a predetermined calculation process is performed on the value of the light quantity data PL, and it is determined whether or not the return light level is appropriate for the target value LT currently set in the register 44.
In step F43, the process branches depending on whether the return light level is larger or smaller than a level at which it can be determined that recording is appropriate for the current target value.
If the return light level is an appropriate level, the process is terminated.
If the return light level is higher than the appropriate level, it is determined that sufficient pits are not formed (laser power is insufficient) due to the skew state and recording film unevenness, and the process proceeds to step F44. Increase the target value LT. That is, the target value LT of the register 44 is rewritten to a higher value.
If the return light level is lower than the appropriate level, sufficient pit formation has been performed, but it is determined that the laser power is too high, and the process proceeds to step F45 to lower the target value LT. That is, the target value LT of the register 44 is rewritten to a lower value.

After the above processing is performed in step F4 in FIG. 8, in the next step F5, it is determined whether or not the address currently being recorded has reached the address of the variable a + ΔA. ΔA is an address amount for setting an interval for skew adjustment. Since the variable a is an address at which data recording was performed when the previous skew adjustment was started, the determination in step F5 is a determination as to whether or not a certain address section has elapsed since the previous skew adjustment.
If the current address has not reached the address of the variable a + ΔA, the process returns to step F4, and the OPC process of FIG. 10 is executed again. In other words, the return light level is captured at the target value LT at that time, it is determined whether or not it is an appropriate level, and the target value LT is updated as necessary.
In other words, in step F5, the OPC process in step F4 is repeatedly performed during a period in which it is determined that a fixed address section has not elapsed since the previous skew adjustment.

If it is determined in step F5 that the current address has reached the address of variable a + ΔA, that is, a fixed address section has elapsed since the previous skew adjustment, the process proceeds to step F6, and the value of variable a is updated to a + ΔA. Return to Step F3. Then, skew adjustment (FIG. 9) is executed. That is, the light quantity data PL acquired in the skew state at that time is set as the evaluation value D0, and the light quantity data PL acquired by swinging the skew state in the + direction and the-direction is set as D1 and D2, and the above-described processing is performed. Converge to a skewed state.
When the skew adjustment in step F3 is completed, the OPC process is executed in step F4.
Note that the processing in FIG. 8 is terminated at the end of the recording operation.

As can be seen from the above processing, in this example, during the recording operation, the skew adjustment is performed every time the recording operation progresses over a certain address section. Then, OPC control is performed during a period during which the fixed address section is in progress.
Since data recording is performed on the disk 1 at a constant linear density, in this case, when viewed from the radial position of the disk, the distance as the radial position where skew adjustment is performed is narrowed toward the outer peripheral side of the disk. It will be.

It is known that the radial inclination of the disk generally tends to increase toward the outer periphery. FIG. 11A shows the radial tilt (tilt) with respect to the radial position.
On the other hand, when the relationship between the radius of the disk and the address is expressed in a graph, it becomes a quadratic curve as shown in FIG. 11B, and shows the same tendency as the inclination of the disk in FIG.
This means that if the skew adjustment is performed for every elapse of a certain address, the outer peripheral portion can be controlled at a finer interval than the inner peripheral portion, that is, the control can be performed at a fine interval where the inclination changes suddenly.
FIG. 11C schematically shows a position where skew adjustment is performed when recording is started from a certain address A0. When data recording from the address A0 to the recording area is performed, skew adjustment is performed for each address section as ΔA, so that as shown in the figure, the skew adjustment portion viewed from the radial position is closer to the outer peripheral side. It becomes dense. As shown in FIG. 11 (a), since the change in the slope becomes larger toward the outer periphery, the variation in the skew state is larger toward the outer periphery, and accordingly, the closer the skew adjustment position is to the outer periphery, the better as the skew adjustment timing. It will be something.

  Further, in this example, skew adjustment is performed at a timing of a certain address section interval as described above, while the running OPC is continuously performed during a period during which the skew adjustment is performed (that is, recording in the address section of ΔA is in progress). Done. For this reason, in this example, the running OPC functions as much as possible during the recording operation, and the skew adjustment is performed at an appropriate timing.

In FIG. 8, the skew adjustment is performed every fixed address section, but the skew adjustment may be performed every fixed time. Since the address can be replaced with time when performing continuous recording, the control sequence can be established even if the control interval is performed based on time. FIG. 12 shows the processing in that case.
When recording starts from a certain address in the system controller 12 step F10, the internal timer T is started in step F12. The timer T is a timer that measures a certain fixed time.
Then, skew adjustment (the process of FIG. 9) is performed in Step F13, and then an OPC process (the process of FIG. 10) is performed in Step F14.
In Step F15, it is confirmed whether or not the timer T has timed out. If not, the OPC process is performed in Step F14. That is, the OPC process is repeatedly executed continuously until the time is over.
When the time is over, the process proceeds from step F15 to F12 to reset the timer T and start counting again. Then, skew adjustment is performed in step F13, and thereafter, the OPC process in step F14 is repeated until the time is over again.

  Also in the case of the processing of FIG. 12, the skew adjustment is performed more densely toward the outer peripheral side as shown in FIG. 11C, and the same effect as in the case of FIG. 8 can be obtained.

As described above, the embodiments have been described, but various modifications can be considered for the present invention.
In the embodiment, the skew drive is performed using the triaxial mechanism 36, but the present invention can also be applied to the case where another skew drive mechanism such as a conventional skew drive mechanism that tilts the entire pickup 3 is used. .
Further, although the embodiment has been described as a disk drive device corresponding to a DVD type disk, the present invention is a recording apparatus corresponding to other types of disk media such as a CD type and a Blu-ray Disc type. But it can be applied.

1 is a block diagram of a disk drive device according to an embodiment of the present invention. It is a disassembled perspective view of the triaxial mechanism of embodiment. It is a perspective view of the triaxial mechanism of an embodiment. It is explanatory drawing of the tilt coil of the triaxial mechanism of embodiment. It is a block diagram of the running OPC / skew control system of the embodiment. It is explanatory drawing of the skew adjustment processing system of embodiment. It is explanatory drawing of the sample timing of the light quantity data of embodiment. 6 is a flowchart of skew adjustment and OPC processing during recording according to the embodiment. It is a flowchart of the skew adjustment processing of the embodiment. It is a flowchart of the running OPC process of an embodiment. It is explanatory drawing of the skew adjustment position of embodiment. 10 is a flowchart of another example of skew adjustment and OPC processing during recording according to the embodiment.

Explanation of symbols

1 disk, 3 pickup, 8 RF amplifier, 12 system controller, 15 laser modulation circuit, 16 sample / hold circuit, 17 A / D converter, 18 D / A converter, 19 skew drive circuit, 36 triaxial mechanism

Claims (2)

A recording head means for recording information at a constant linear density by irradiating a laser beam so as to combine a period for forming a pit mark and an erase period on a disk recording medium;
The power of the laser beam output from the recording head means when the magnitude of the light amount data, which is a signal obtained by sampling the return beam of the laser beam irradiated onto the disk recording medium, is higher than a predetermined level A laser power control means for variably controlling the power of the laser light output from the recording head means when the magnitude of the light quantity data is lower than a predetermined level.
Skew drive means for varying the inclination of the optical axis of the laser beam with respect to the disk recording medium by applying a current to a tilt coil of a triaxial mechanism ;
While controlling the skew driving means, the light amount data obtained by sampling the return light of the laser light irradiated on the disk recording medium during the erase period is detected, and the light amount data is minimum or the light amount data. Skew control means for adjusting the inclination of the optical axis of the laser beam with respect to the disk recording medium so that the change rate of
During the recording operation by the recording head means, the processing by the skew control means is executed at a constant address interval , and the laser power during the constant address interval when the processing by the skew control means is not executed. Execution control means for repeatedly executing processing in the control means;
Recording device. When recording information with a constant linear density by irradiating a laser beam so as to combine a period for forming a pit mark and an erase period on a disk recording medium,
If the magnitude of the light quantity data, which is a signal obtained by sampling the return light of the laser light applied to the disk recording medium, is higher than a predetermined level, the power of the laser light is increased and the light quantity is increased. A laser power control step for variably controlling so that the power of the laser beam is lowered when the data size is lower than a predetermined level;
While the tilt of the optical axis of the laser beam with respect to the disk recording medium is changed by applying a current to the tilt coil of the triaxial mechanism, the return light of the laser light irradiated on the disk recording medium is sampled during the erase period. A skew control step of detecting the light amount data obtained and adjusting an inclination of an optical axis of the laser beam with respect to the disk recording medium so that the light amount data is minimum or a change rate of the light amount data is not more than a predetermined value. When,
Have
A recording method in which the processing of the skew control step is executed at a constant address interval , and the laser power control step is repeatedly executed during the fixed address interval when the skew control step is not executed.

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