JP4001024B2 - Disk drive device, focus bias, and spherical aberration adjustment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disk drive device for a disk recording medium such as an optical disk, and a focus bias and spherical aberration adjustment adjustment method.
[0002]
[Prior art]
[Patent Document 1]
JP 2002-352449 A
[Patent Document 2]
JP-A-10-269611
[Patent Document 3]
JP 2000-285484 A
[Patent Document 4]
JP-A-9-251645
[Patent Document 5]
JP2000-11388
[0003]
As a technique for recording / reproducing digital data, optical disks (including magneto-optical disks) such as CD (Compact Disk), MD (Mini-Disk), and DVD (Digital Versatile Disk) are used as recording media. There is data recording technology. An optical disk is a generic term for recording media that irradiate laser light onto a disk in which a thin metal plate is protected with plastic, and read signals by changes in reflected light.
The optical disc includes, for example, a read-only type as known as CD, CD-ROM, DVD-ROM, MD, CD-R, CD-RW, DVD-R, DVD-RW, DVD + RW, DVD -There is a type in which user data can be recorded as known in RAM and the like. In the recordable type, data can be recorded by using a magneto-optical recording method, a phase change recording method, a dye film change recording method, or the like. The dye film change recording method is also called a write-once recording method, and can be recorded only once and cannot be rewritten. On the other hand, the magneto-optical recording method and the phase change recording method can rewrite data and are used for various purposes such as recording of various content data such as music, video, games, application programs and the like.
In recent years, a high-density optical disk called a Blu-ray Disc has been developed, and the capacity has been significantly increased.
[0004]
For a high-density disc such as a Blu-ray disc, in a disc structure having a cover layer of 0.1 mm in the disc thickness direction, a laser with a wavelength of 405 nm (so-called blue laser) and an objective lens with NA (Numerical Aperture) of 0.85 are used. When recording / reproducing a phase change mark (phase change mark) under the condition of combination, a data block of 64 KB (kilobytes) with a track pitch of 0.32 μm, a linear density of 0.12 μm / bit, When the format efficiency is about 82%, a capacity of about 23.3 GB (gigabytes) can be recorded and reproduced on a direct 12 cm disk.
If the linear density is 0.112 μm / bit in the same format, a capacity of 25 GB can be recorded and reproduced.
Furthermore, a dramatic increase in capacity can be realized by providing the recording layer with a multilayer structure. For example, by using two recording layers, the capacity can be 46.6 GB or 50 GB, which is twice the above.
[0005]
[Problems to be solved by the invention]
By the way, as already known, in a disk drive device that performs recording / reproduction on an optical disk, a focus servo operation for controlling the focal position of the laser beam to the disk recording surface, or the laser beam is caused by a track (pit row or groove (groove)) on the disk. A tracking servo operation is performed to control to track).
Regarding the focus servo, it is known that it is necessary for an appropriate servo operation to apply an appropriate focus bias to the focus loop.
[0006]
In particular, in the case of a high-density disk, it is necessary to correct spherical aberration in order to cope with a cover layer thickness error or a multilayered recording layer. For example, an expander or a liquid crystal element is used in an optical pickup. A device having a spherical aberration correction mechanism has been developed, and is disclosed in, for example, Patent Documents 1 and 2 above.
[0007]
In particular, in a writable disc drive device (recording / reproducing device) having a high NA lens such as the above-mentioned Blu-ray disc, the focus bias / spherical aberration margin is narrow, and therefore automatic adjustment of the focus bias and spherical aberration is essential. Is done.
As a technique for adjusting the focus bias, for example, Patent Document 3 is known.
Also, for example, Japanese Patent Application Laid-Open No. 2004-133620 is known as a method for adjusting spherical aberration.
Further, a method for simultaneously adjusting the focus bias / spherical aberration is disclosed in Patent Document 5.
[0008]
However, the conventional methods of focus bias adjustment and spherical aberration adjustment have the following problems. This will be described with reference to FIGS.
[0009]
Normally, focus bias adjustment and spherical aberration adjustment are adjusted so that the RF signal amplitude is maximized.
In FIG. 17A, the vertical axis represents the RF amplitude value, and the horizontal axis represents the spherical aberration correction value (or the same when the focus bias value is used). This is the RF with respect to the spherical aberration correction value (or the focus bias value). The case where the characteristic of the amplitude value is ideal is shown.
[0010]
Hereinafter, the spherical aberration correction value will be described as an example.
For example, when the level LV1 as the RF signal amplitude value is set to the lower limit of the allowable range, the spherical aberration correction value may be adjusted to the value X1 in FIG. 17A, that is, the value at which the RF signal amplitude value becomes the maximum value LV2.
Then, as the spherical aberration, the maximum margin width can be taken as shown in the figure.
[0011]
However, in practice, the characteristics of the RF amplitude value with respect to the spherical aberration correction value rarely become ideal as shown in FIG. 17A. For example, a mountain-shaped curve as shown in FIG. There may be some indented characteristics.
In this case, when the spherical signal correction value X2 at which the RF signal amplitude value becomes the maximum value LV2 is adjusted, the margin width becomes narrow.
In addition, as shown in FIG. 17C, although the characteristic is a mountain-shaped curve, the characteristic may be such that the vertex is shifted.
Also in this case, if the RF signal amplitude value is adjusted to the spherical aberration correction value X3 at which the maximum value is LV2, the margin width becomes narrow.
Furthermore, as shown in FIG. 17 (d), there may be a characteristic having the characteristics as shown in FIGS. 17 (b) and 17 (c). In this case as well, spherical aberration correction in which the RF signal amplitude value becomes the maximum value LV2 is possible. When the value is adjusted to X4, the margin width becomes narrow.
Although the adjustment of the spherical aberration correction value has been described, the same applies to the focus bias value.
[0012]
That is, in the conventional method, it is assumed that an amplitude value as shown in FIG. 17A is obtained in which the point at which the RF signal amplitude is maximum is at the center of the margin. For this reason, the variation of the actually sampled amplitude value is large and becomes as shown in FIGS. 17B, 17C, and 17D, so that the adjustment accuracy is deteriorated and the margin width is narrowed. There is.
[0013]
In order to avoid such a problem, it is conceivable to increase the number of samples of the RF signal amplitude value. Then, the characteristic of the sampled amplitude value can be brought closer to the state of FIG. 17B to FIG. 17C, for example, and the adjustment accuracy can be improved.
However, in this case, there is a problem that the time required for the adjustment becomes long, and for example, in the case of the state as shown in FIGS.
For these reasons, simply adjusting the spherical aberration correction value or the focus bias value to the maximum value of the RF signal amplitude value has a limit in increasing the adjustment accuracy.
[0014]
Further, it is not appropriate to individually adjust the focus bias value and the spherical aberration correction value for the following reasons.
In general, the relationship between the focus bias, spherical aberration, and RF signal amplitude value is as shown in FIG. In this figure, the RF signal amplitude value when the maximum is 100 is shown in relation to the focus bias / spherical aberration.
[0015]
If the relationship is as shown in FIG. 18B, there is no problem even if the focus bias / spherical aberration is individually adjusted.
For example, assume that the initial state of the focus bias / spherical aberration is a value corresponding to the point A in FIG. In this case, if the spherical aberration adjustment is performed first, the spherical aberration adjustment is performed on the spherical aberration correction value corresponding to the point B at which the RF signal amplitude value is maximum on the line L1.
Thereafter, when the focus bias adjustment is performed this time, the focus bias adjustment is performed to the focus bias value corresponding to the point C at which the RF signal amplitude value is maximum on the line L2.
Then, this point C is a point at which the RF signal amplitude value becomes the maximum when viewed from either the focus bias / spherical aberration, that is, it may be adjusted individually.
[0016]
However, since the actual relationship is as shown in FIG. 18 (a), it is not possible to adjust to the point where the RF signal amplitude value is maximized by adjusting individually, in terms of either focus bias or spherical aberration.
For example, assume that the initial state of the focus bias / spherical aberration is a value corresponding to the point A in FIG. In this case, when the spherical aberration adjustment is first performed, the spherical aberration adjustment is performed to the spherical aberration correction value corresponding to the point B at which the RF signal amplitude value is maximum on the line L1.
Thereafter, when the focus bias adjustment is performed this time, the focus bias adjustment is performed to the focus bias value corresponding to the point C at which the RF signal amplitude value is maximum on the line L2.
In this case, the point C is not the point at which the RF signal amplitude value is maximized when viewed from either the focus bias / spherical aberration.
Thus, appropriate adjustment cannot be performed by adjusting individually.
[0017]
On the other hand, in order to avoid such a problem, a method of simultaneously performing focus bias / spherical aberration adjustment is disclosed in Patent Document 5.
However, even if the focus bias / spherical aberration is adjusted at the same time, the above-described problem, that is, the problem that the margin cannot always be adjusted to the maximum margin, remains in the method of adjusting the RF signal amplitude to the maximum value.
[0018]
Further, in the case of a data writable disc (writable disc), there are the following problems.
In the case of a read-only disk (so-called ROM disk), data is recorded in advance with embossed pits, etc. Therefore, even during focus bias adjustment and spherical aberration adjustment, the already recorded data is reproduced and the RF signal amplitude is increased. It will be detected and adjusted accordingly.
However, in the case of a writable disc, data is not originally recorded. Therefore, in order to perform focus bias adjustment and spherical aberration adjustment, adjustment data to be read at the time of adjustment must be recorded in advance.
Here, if there is a variation in the adjustment data in terms of recording conditions, for example, the influence of cross light, the variation in the RF signal amplitude to be reproduced increases accordingly. This deteriorates the adjustment accuracy of focus bias adjustment and spherical aberration adjustment.
[0019]
[Means for Solving the Problems]
In view of the above problems, an object of the present invention is to make it possible to accurately and efficiently execute the adjustment of the focus bias / spherical aberration.
[0020]
For this purpose, the disk drive device of the present invention performs laser irradiation and reflected light detection on a disk recording medium for writing or reading data, and a head having a laser beam focus servo mechanism and a spherical aberration correction mechanism. Means, an evaluation value generating means for generating an evaluation value from a signal based on the reflected light obtained by the head means, and the focus servo based on a focus error signal generated as a signal based on the reflected light obtained by the head means Focus servo means for driving the mechanism to perform focus servo, spherical aberration adjustment means for driving the spherical aberration correction mechanism to perform spherical aberration adjustment based on the spherical aberration correction value, and focus including the focus servo means A focus bias means for adding a focus bias to the loop; -While changing both the bias bias value and the spherical aberration correction value, as the tolerance limit point of the evaluation value, two tolerance limit points at which the evaluation values are substantially equivalent are searched, and an intermediate point between the two tolerance limit points Control means for adjusting the focus bias value and the spherical aberration correction value so as to correspond to The disk recording medium in which data writing for adjusting the focus bias and the spherical aberration is performed on the disk recording medium in a plurality of circular track ranges from the inner circumference side to the outer circumference side, and then the data writing is performed. In the upper range, the adjustment use range to be reproduced during the adjustment process of the focus bias and the spherical aberration is within the multi-round track range, and the track on which the data writing has been performed on the outer periphery side. Adjustment use range setting means to set the adjustment use range within the existing range With.
The evaluation value generating means generates a jitter value, a reproduction signal amplitude value, or an asymmetry value as the evaluation value when reproducing data from the disk recording medium.
Further, when searching for the permissible limit point, the control means changes one of the focus bias value and the spherical aberration correction value in a stepwise manner and changes the other in each step to obtain the optimum A process for obtaining an evaluation value is performed.
[0022]
The focus bias and spherical aberration adjustment method of the present invention reproduces a disk recording medium while changing both the focus bias value and the spherical aberration correction value, and generates an evaluation value from a signal based on the reflected light at that time. An evaluation value generation step, an allowable limit point determination step for determining an allowable limit point based on the evaluation value, and two allowable limit points determined in the allowable limit point determination step and having substantially the same evaluation value. An intermediate point determining step for determining an intermediate point between the two allowable limit points, and an adjusting step for adjusting the focus bias value and the spherical aberration correction value so as to correspond to the intermediate point, In the adjustment step, data writing used for adjusting the focus bias and the spherical aberration is performed on the disk recording medium from the inner circumference side to the outer circumference side in a plurality of circular track ranges, and then the data writing is performed. Within the range on the disc recording medium that has been performed, the adjustment use range to be reproduced during the adjustment process of the focus bias and the spherical aberration is within the multi-round track range, and the data writing is performed on the outer peripheral side. An adjustment use range setting step is provided for setting the adjustment use range within the range where the performed track exists. ing.
In the evaluation value generation step, a jitter value, a reproduction signal amplitude value, or an asymmetry value is generated as the evaluation value.
Further, in the allowable limit point determination step, one of the focus bias value and the spherical aberration correction value is changed stepwise, and at each step, the other is changed to obtain the optimum evaluation value. .
[0023]
In the present invention having the above configuration, the focus bias / spherical aberration is adjusted simultaneously. Further, the deterioration of adjustment accuracy due to the small number of evaluation value samplings is prevented, and the time required for adjustment is shortened. The RF signal amplitude value or the like is used as the evaluation value, but the adjustment can be made to the margin center even when the maximum amplitude is deviated from the center of the margin.
In addition, setting the range used for adjusting the focus bias and the spherical aberration within the range where the data writing used for the adjustment process for the focus bias and the spherical aberration is executed, uses the range of the same condition during the adjustment. It means to do.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, as an embodiment of the present invention, a disk drive device (recording / reproducing device) that performs recording / reproduction corresponding to an optical disc is taken as an example, data writing and laser power adjustment for adjusting a focus bias and spherical aberration, and The focus bias / spherical aberration adjustment executed thereafter will be described. The description will be given in the following order.
1. Configuration of disk drive device
2. Spherical aberration correction mechanism
3. Servo system configuration
4). Configuration for obtaining evaluation values
5). Adjustment processing for writable discs and playback-only discs
6). Write data for adjustment and rough OPC processing
7). Setting range for adjustment
8). Spherical aberration and focus bias adjustment
9. Adjustment timing
[0025]
1. Configuration of disk drive device
FIG. 1 shows the configuration of the disk drive device of this example.
The disk 1 is assumed to be an optical disk (writable disk) that records data by a phase change method, for example. Further, a wobbling (meandering) groove is formed on the disk, and this groove is used as a recording track. Depending on the wobbling of the groove, address information or the like is embedded as so-called ADIP information.
Note that a read-only disc on which data is recorded by embossed pits may be loaded as the disc 1.
[0026]
Such a disk 1 is loaded on a turntable (not shown) and is rotationally driven by a spindle motor 52 at a constant linear velocity (CLV) during a recording / reproducing operation.
Then, ADIP information embedded as wobbling of the groove track on the disk 1 is read by the optical pickup (optical head) 51.
At the time of recording, the user data is recorded on the track as a phase change mark by the optical pickup 51, and at the time of reproduction, the phase change mark recorded by the optical pickup is read out.
[0027]
In the pickup 51, 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 a laser recording light are irradiated onto the disk recording surface via the objective lens. An optical system (described later) for guiding the reflected light to the photodetector is formed.
The laser diode outputs a so-called blue laser having a wavelength of 405 nm, for example. The NA by the optical system is 0.85.
[0028]
The objective lens is held in the pickup 51 so as to be movable in the tracking direction and the focus direction by a biaxial mechanism.
The entire pickup 51 can be moved in the radial direction of the disk by a thread mechanism 53.
The laser diode in the pickup 51 is driven to emit laser light by a drive signal (drive current) from the laser driver 63.
[0029]
As will be described later, the pickup 51 is provided with a mechanism for correcting the spherical aberration of the laser light, and the spherical aberration is corrected by the control of the system controller 60 and the servo circuit 62.
[0030]
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 matrix circuit 54.
The matrix circuit 54 includes a current-voltage conversion circuit, a matrix calculation / amplification circuit, and the like corresponding to output currents from a plurality of light receiving elements as photodetectors, and generates necessary signals by matrix calculation processing.
For example, a high-frequency signal (also referred to as a reproduction data signal or an RF signal) corresponding to reproduction data, a focus error signal for servo control, a tracking error signal, and the like are generated.
Further, a push-pull signal is generated as a signal related to groove wobbling, that is, a signal for detecting wobbling.
[0031]
The reproduction data signal output from the matrix circuit 54 is supplied to the reader / writer circuit 55, the focus error signal and tracking error signal are supplied to the servo circuit 61, and the push-pull signal is supplied to the wobble circuit 58.
[0032]
The reader / writer circuit 55 performs binarization processing on the reproduction data signal, reproduction clock generation processing by PLL, etc., reproduces the data read out as the phase change mark, and supplies it to the modulation / demodulation circuit 56.
The modem circuit 56 includes a functional part as a decoder at the time of reproduction and a functional part as an encoder at the time of recording.
At the time of reproduction, as a decoding process, a run-length limited code is demodulated based on the reproduction clock.
The ECC encoder / decoder 57 performs an ECC encoding process for adding an error correction code at the time of recording and an ECC decoding process for correcting an error at the time of reproduction.
At the time of reproduction, the data demodulated by the modulation / demodulation circuit 56 is taken into an internal memory, and error detection / correction processing and deinterleaving processing are performed to obtain reproduction data.
The data decoded to the reproduction data by the ECC encoder / decoder 57 is read out and transferred to an AV (Audio-Visual) system 120 based on an instruction from the system controller 60.
[0033]
The push-pull signal output from the matrix circuit 54 as a signal related to groove wobbling is processed in the wobble circuit 58. The push-pull signal as ADIP information is demodulated into a data stream constituting an ADIP address in the wobble circuit 58 and supplied to the address decoder 59.
The address decoder 59 decodes the supplied data, obtains an address value, and supplies it to the system controller 10.
The address decoder 9 generates a clock by PLL processing using the wobble signal supplied from the wobble circuit 8, and supplies it to each unit as an encode clock at the time of recording, for example.
[0034]
At the time of recording, recording data is transferred from the AV system 120. The recording data is sent to a memory in the ECC encoder / decoder 57 and buffered.
In this case, the ECC encoder / decoder 57 performs error correction code addition, interleaving, subcode addition, and the like as encoding processing of the buffered recording data.
The ECC-encoded data is subjected to RLL (1-7) PP modulation in the modulation / demodulation circuit 56 and supplied to the reader / writer circuit 55.
As described above, the clock generated from the wobble signal is used as the reference clock for the encoding process during recording.
[0035]
The recording data generated by the encoding process is subjected to recording compensation processing by the reader / writer circuit 55, and fine adjustment of the optimum recording power and adjustment of the laser drive pulse waveform with respect to recording layer characteristics, laser beam spot shape, recording linear velocity, etc. Etc. are sent to the laser driver 63 as a laser drive pulse.
The laser driver 63 applies the supplied laser drive pulse to the laser diode in the pickup 51 to perform laser emission driving. As a result, pits (phase change marks) corresponding to the recording data are formed on the disc 1.
[0036]
The laser driver 63 includes a so-called APC circuit (Auto Power Control), and the laser output is not dependent on the temperature or the like while monitoring the laser output power by the output of the laser power monitoring detector provided in the pickup 51. Control to be constant.
The target value (recording laser power / reproducing laser power) of the laser output at the time of recording and reproduction is given from the system controller 60, and the laser output level is controlled to be the target value at the time of recording and reproduction.
[0037]
The servo circuit 61 generates various servo drive signals for focus, tracking, and thread from the focus error signal and tracking error signal from the matrix circuit 54, and executes the servo operation.
That is, a focus drive signal and a tracking drive signal are generated according to the focus error signal and tracking error signal, and the focus coil and tracking coil of the biaxial mechanism in the pickup 51 are driven. Thus, a pickup 51, a matrix circuit 54, a servo circuit 61, a tracking servo loop and a focus servo loop by a biaxial mechanism are formed.
[0038]
The servo circuit 61 turns off the tracking servo loop and outputs a jump drive signal in response to a track jump command from the system controller 60, thereby executing a track jump operation.
[0039]
The servo circuit 61 generates a thread drive signal based on a thread error signal obtained as a low frequency component of the tracking error signal, access execution control from the system controller 60, and the like, and drives the thread mechanism 53. Although not shown, the sled mechanism 53 has a mechanism including a main shaft that holds the pickup 51, a sled motor, a transmission gear, and the like, and by driving the sled motor according to a sled drive signal, a required slide of the pick-up 51 is obtained. Movement is performed.
[0040]
The spindle servo circuit 62 performs control to rotate the spindle motor 2 at CLV.
The spindle servo circuit 62 obtains the clock generated by the PLL processing for the wobble signal as the current rotational speed information of the spindle motor 52 and compares it with predetermined CLV reference speed information to generate a spindle error signal. .
At the time of data reproduction, the reproduction clock (clock serving as a reference for decoding processing) generated by the PLL in the reader / writer circuit 55 becomes the current rotational speed information of the spindle motor 52, and this is used as a predetermined CLV. A spindle error signal can also be generated by comparing with the reference speed information.
The spindle servo circuit 62 outputs a spindle drive signal generated according to the spindle error signal, and causes the spindle motor 62 to perform CLV rotation.
The spindle servo circuit 62 generates a spindle drive signal in response to a spindle kick / brake control signal from the system controller 60, and executes operations such as starting, stopping, acceleration, and deceleration of the spindle motor 2.
[0041]
Various operations of the servo system and the recording / reproducing system as described above are controlled by a system controller 60 formed by a microcomputer.
The system controller 60 executes various processes according to commands from the AV system 120.
[0042]
For example, when a write command (write command) is issued from the AV system 120, the system controller 60 first moves the pickup 51 to the address to be written. Then, the ECC encoder / decoder 57 and the modulation / demodulation circuit 56 execute the encoding process as described above on the data transferred from the AV system 120 (for example, video data of various systems such as MPEG2 or audio data). Then, recording is executed by supplying the laser drive pulse from the reader / writer circuit 55 to the laser driver 63 as described above.
[0043]
For example, when a read command for transferring certain data (MPEG2 video data or the like) recorded on the disk 1 is supplied from the AV system 120, seek operation control is first performed for the instructed address. That is, a command is issued to the servo circuit 61 to cause the pickup 51 to access the address specified by the seek command.
Thereafter, operation control necessary for transferring the data in the designated data section to the AV system 120 is performed. That is, data reading from the disk 1 is performed, decoding / buffering and the like in the reader / writer circuit 55, the modem circuit 56, and the ECC encoder / decoder 57 are executed, and the requested data is transferred.
[0044]
When recording / reproducing data using these phase change marks, the system controller 60 controls access and recording / reproducing operations using the ADIP addresses detected by the wobble circuit 58 and the address decoder 59.
[0045]
1 is a disk drive device connected to the AV system 120, the disk drive device of the present invention may be connected to, for example, a personal computer.
Furthermore, there may be a form that is not connected to other devices. In this case, an operation unit and a display unit are provided, and the configuration of the interface part for data input / output is different from that in FIG. That is, it is only necessary that recording and reproduction are performed in accordance with a user operation and a terminal unit for inputting / outputting various data is formed.
Of course, there are various other configuration examples. For example, examples of a recording-only device and a reproduction-only device are also possible.
[0046]
2. Spherical aberration correction mechanism
The spherical aberration correction mechanism in the pickup 51 is formed as shown in FIG. 2 and FIG. 3, the optical system in the pickup 51 is shown.
[0047]
In FIG. 2, laser light output from a semiconductor laser (laser diode) 81 is converted into parallel light by a collimator lens 82, passes through a beam splitter 83, and is a movable lens 87 and a fixed lens 88 as a spherical aberration correction lens group. , And the disc 1 is irradiated from the objective lens 84. The spherical aberration correction lens groups 87 and 88 are called expanders. Since spherical aberration correction is performed by driving the movable lens 87, hereinafter, it may be expressed in particular as an expander 87.
[0048]
The reflected light from the disk 1 passes through the objective lens 84, the fixed lens 88, and the movable lens 87, is reflected by the beam splitter 83, and enters the detector 86 through the collimator lens (condensing lens 85).
[0049]
In such an optical system, the objective lens 84 is supported by the biaxial mechanism 91 so as to be movable in the focus direction and the tracking direction, and focus servo and tracking servo operations are performed.
The spherical aberration correction lenses 87 and 88 have a function of changing the diameter of the laser beam. That is, the movable lens 87 can be moved in the J direction, which is the optical axis direction, by the actuator 90, and the diameter of the laser light applied to the disk 1 is adjusted by this movement.
In other words, spherical aberration correction can be performed by performing control for causing the actuator 90 to move back and forth.
[0050]
The example of FIG. 3A includes a liquid crystal panel 89 in place of the spherical aberration correction lenses 87 and 88 in the same optical system as in FIG.
That is, in the liquid crystal panel 89, the diameter of the laser beam can be varied by variably adjusting the boundary between the region where the laser beam is transmitted and the region where the laser beam is shielded as shown by the solid line, broken line, and alternate long and short dash line in FIG. is there.
In this case, spherical aberration correction can be performed by controlling the liquid crystal driver 92 that drives the liquid crystal panel 89 so as to change the transmission region.
[0051]
3. Servo system configuration
In the servo circuit 61 in FIG. 1, a portion for forming the above-described focus servo loop and tracking servo loop and a portion related to setting of the spherical aberration correction value are shown in FIG.
[0052]
The focus error signal FE and the tracking error signal TE from the matrix circuit 54 are converted into digital data by the A / D converters 11 and 21, respectively, in the servo circuit 61 and input to the DSP 10.
The DSP 10 has functions as a focus servo calculation unit 12 and a tracking servo calculation unit 22.
[0053]
The focus error signal FE from the A / D converter 11 is input to the focus servo calculation unit 12 via the adder 15.
The focus servo calculation unit 12 generates and outputs a focus servo signal by performing predetermined calculations such as filtering for phase compensation and loop gain processing on the focus error signal FE input as digital data. . The focus servo signal is converted into an analog signal by the D / A converter 13 (including PWM and PDM) and then input to the focus driver 14 to drive the focus actuator. That is, a current is applied to the focus coil of the biaxial mechanism 91 that holds the objective lens 84 in the optical pickup 51, and the focus servo operation is executed.
[0054]
The tracking servo calculation unit 22 performs predetermined calculations such as filtering for phase compensation and loop gain processing on the tracking error signal TE input as digital data, and generates and outputs a tracking servo signal. . The tracking servo signal is converted into an analog signal by the D / A converter 23 (including PWM and PDM), and then input to the tracking driver 24 to drive the tracking actuator. That is, a current is applied to the tracking coil of the biaxial mechanism 91 that holds the objective lens 84 in the optical pickup 51 to execute a tracking servo operation.
[0055]
The DSP 10 is provided with functional parts for focus bias addition, spherical aberration correction value setting, and adjustment of the focus bias and spherical aberration correction value.
The adder 15 adds a focus bias to the focus error signal FE. The focus bias value to be added is set in the focus bias setting unit 16. The focus bias setting unit 16 outputs a focus bias value set in an adjustment process described later, whereby an appropriate focus bias is added to the focus servo loop.
[0056]
The spherical aberration correction value setting unit 20 sets a spherical aberration correction value by a spherical aberration correction mechanism. The set spherical aberration correction value is converted into an analog signal by the D / A converter 25 and supplied to the spherical aberration correction driver 26.
For example, in the case of a spherical aberration correction mechanism as shown in FIG. 2, the spherical aberration correction driver 26 is a circuit that supplies a drive signal Sd to an actuator 90 that moves the expander 87. In the case of the spherical aberration correction mechanism as shown in FIG. 3, the circuit supplies a signal Sd for instructing the liquid crystal driver 92 to apply a voltage to a required cell of the liquid crystal panel 84.
Therefore, the spherical aberration correction driver 26 drives the spherical aberration correction mechanism in the pickup 51 based on the spherical aberration correction value supplied from the spherical aberration correction value setting unit 20.
[0057]
The nonvolatile memory 18 stores an initial value as a focus bias value and a spherical aberration setting value, and further, an adjustment value obtained by focus bias / spherical aberration adjustment described later, that is, an optimal focus bias value and spherical aberration correction. Remember the value.
The setting control unit 17 sets the setting value in the focus bias setting unit 16 and the setting value in the spherical aberration correction value setting unit 20. For example, the setting value is set to a value stored in the nonvolatile memory 18 or each setting value is changed according to an instruction from the system controller 60.
[0058]
As described above, the operation related to the adjustment of the focus servo / spherical aberration correction value formed by the DSP 10 and the focus servo calculation unit 22 and the tracking servo calculation unit 22 is controlled by the system controller 60.
[0059]
4). Configuration for obtaining evaluation values
In the disk drive device of the present embodiment, when performing laser power adjustment and focus bias / spherical aberration adjustment, which will be described later, jitter values and reproduction data amplitude values (RF amplitude values) are used as evaluation values for optimum adjustment. Alternatively, an asymmetry value is used.
A configuration example for obtaining these evaluation values is shown in FIG.
[0060]
The evaluation value can be obtained from a signal based on the reflected light obtained by the photodetector 86 in the pickup 51, that is, a signal generated by being processed by the matrix circuit 54. In the case of this example, in particular, the reader / writer circuit 55 is configured as shown in FIG. 5 in order to obtain a value obtained from the reproduction data signal (RF signal).
[0061]
As shown in the figure, the reader / writer circuit 55 includes a write waveform generation unit 31, a binarization circuit 32, an RF reproduction processing unit 33, a PLL circuit 34, and an evaluation value calculation unit 35.
The write waveform generator 31 performs optimum recording power for the recording layer characteristics, laser beam spot shape, recording linear velocity, etc. as recording compensation processing for the recording data encoded by the modem circuit 56 during recording operation. Fine adjustment and adjustment of laser drive pulse waveform. The signal subjected to these processes is supplied to the laser driver 63 as a laser drive pulse.
During reproduction, the reproduction data signal (RF signal) from the matrix circuit 54 is binarized by the binarization circuit 32. Further, a reproduction clock is generated by the PLL circuit 34 based on the binarized data.
The binarized data is processed in the RF reproduction processing unit 33 based on the reproduction clock, converted into data read from the phase change mark, and supplied to the modulation / demodulation circuit 56.
[0062]
The evaluation value calculator 35 calculates a jitter value on the processing of the RF reproduction processor 33.
Alternatively, peak / bottom detection is performed on the amplitude of the reproduction data signal (RF signal) to calculate the RF amplitude value.
Further, an asymmetry value indicating the symmetry of the reproduction RF signal may be calculated.
The evaluation value calculator 35 supplies the jitter value, RF amplitude value, or asymmetry value obtained as these evaluation values to the system controller 60.
[0063]
5). Adjustment processing for writable discs and playback-only discs
An adjustment process for the disk 1 loaded in the disk drive apparatus will be described.
When the disc 1 is a writable disc (writable disc) with a phase change mark as described above, for example, the adjustment process shown in FIG. 6A is performed when the disc is loaded.
[0064]
First, as step S1, adjustment data writing and coarse OPC are performed.
Next, in step S2, the adjustment use range used for the focus bias / spherical aberration adjustment is set in the range on the disk where the adjustment data is written.
Next, as step S3, focus bias / spherical aberration adjustment is performed.
In step S4, OPC (laser power adjustment) is performed.
[0065]
In the case of a writable disc, no data is recorded on tracks formed by grooves on the disc. The adjustment of focus bias and spherical aberration is performed while reproducing the test writing area (test area) on the disc. However, since data is not originally recorded, adjustment data is prepared as preparation processing for these adjustments. Must be written to the test writing area on the disc. For this reason, as step S1, the adjustment data is written in the test writing area on the disk.
[0066]
By the way, at the time of this first procedure S1, laser power adjustment has not been performed yet. For this reason, normally, adjustment data is written at a laser power as a preset initial value (for example, a recommended laser power value recorded as management information on the disk 1).
However, in the relationship between the combination of the disk 1 and the disk drive device, the optimum value of the laser power is different, and the optimum value of the laser power is adjusted in step S4 after the focus bias and spherical aberration adjustment in step S3. Is.
For this reason, normally, the adjustment data is written simply with the recording laser power as the initial value. In this case, however, the recording laser power is not necessarily appropriate. There are cases where this is not preferable for bias / spherical aberration adjustment.
Therefore, in this example, when the adjustment data is written in step S1, rough laser power adjustment is performed as coarse OPC. That is, the purpose of the rough OPC is to perform adjustment data writing with an appropriate signal quality so that the focus bias / spherical aberration adjustment can be performed with high accuracy.
[0067]
The adjustment use range setting process in step S2 is also performed to improve the accuracy of focus bias / spherical aberration adjustment, and will be described in detail later.
[0068]
In step S3, the spherical aberration and the focus bias are adjusted simultaneously. Although this process will also be described later, the adjustment accuracy is improved by simultaneously adjusting the spherical aberration and the focus bias after using the adjustment data recorded with the appropriate recording laser power by the coarse OPC.
Then, after adjusting the focus bias / spherical aberration, a process for optimizing the recording laser power and the reproducing laser power for a normal recording / reproducing operation is executed as the OPC process in step S4.
[0069]
When the disk 1 is a read-only disk (ROM disk) in which data is recorded in advance by embossed pits, for example, the adjustment process shown in FIG. 6B is performed when the disk is loaded.
In this case, it is not necessary to write the adjustment data or set the adjustment use range. In step S11, the focus bias / spherical aberration adjustment is performed while reproducing a certain area on the disk. Power adjustment) is performed.
In this case as well, the focus bias / spherical aberration adjustment can be performed simultaneously by the processing described later, thereby improving the adjustment accuracy.
[0070]
6). Write data for adjustment and rough OPC processing
As described above, in this example, when a writable disk is loaded, adjustment data is written as a pre-stage of focus bias / spherical aberration adjustment, and at that time, focus bias / spherical surface is used as coarse OPC. For aberration adjustment, recording laser power adjustment is performed to guarantee the quality of the adjustment data.
[0071]
A specific example of the process in this case, that is, the process in step S1 of FIG. 7 is shown as a control process by the system controller 60. In this case, it is assumed that the jitter value is supplied to the system controller 60 from the evaluation value calculator 35 of FIG. 5 as the evaluation value.
[0072]
First, in step F101, the system controller 60 sets the value of the recording laser power PWw to the initial value IP. That is, it instructs the laser driver 63 that the recording laser power PWw = IP. The initial value IP is, for example, a recommended recording laser power value recorded as management information of the disk 1 or a value preset by the system controller 60.
In step F102, the servo circuit 61 is instructed to cause the pickup 51 to access the test writing area on the disk 1, and the adjustment data is written by the pickup 51. At this time, laser output is performed with recording laser power PWw = initial value IP.
[0073]
When the recording of the adjustment data in the test writing area is completed, the system controller 60 reproduces the written adjustment data and acquires the jitter value in step F103.
That is, the adjustment data is reproduced by the pickup 51, and the RF signal is processed by the reader / writer circuit 55. At this time, the jitter value is calculated by the evaluation value calculator 35 and supplied to the system controller 60.
The system controller 60 holds the supplied jitter value as a variable RCP0.
[0074]
In step F104, the system controller 60 performs processing for comparing the jitter value held as the variable RCP0 with a predetermined value Lim1 set in advance. If RCP0 ≦ Lim1, the process of FIG. 7 is finished as shown in (1).
This case will be described with reference to FIG.
FIG. 8A shows the characteristic of the jitter value with respect to the recording laser power. The predetermined value Lim1 (and Lim2 to be described later) is set as a rough OPC threshold value using a jitter value as an evaluation value. As an example, Lim1 has a jitter value of 12% and Lim2 has a jitter value of 15%. . Although the meaning will be described later, as the rough OPC, the recording laser power PWw is set to a power that exceeds the lower limit with a level at which the jitter value is at least 15% or less.
[0075]
In the case of (1) in which RCP0 ≦ Lim1 in step F104, after recording data for adjustment with recording laser power PWw = initial value IP, reproduction and observation of the jitter value result in the jitter value (RCP0) being In this case, as shown in FIG.
In this case, assuming that the initial value IP is a value suitable for writing adjustment data for the subsequent focus bias / spherical aberration adjustment, the adjustment data writing and the rough OPC processing are finished.
[0076]
If RCP0 ≦ Lim1 is not satisfied in step F104, the system controller 60 proceeds to step F105, and whether the jitter value (RCP0) is equal to or smaller than a predetermined value Lim2 (for example, 15%), that is, whether Lim1 <RCP0 ≦ Lim2. Is determined.
If Lim1 <RCP0 ≦ Lim2, the process proceeds to step F106 as indicated by (2), and the recording laser power PWw is changed to the initial value IP + α. In step F107, the adjustment data is written again, and the process of FIG. 7 is completed. That is, the adjustment data writing is performed in a state where the value of the recording laser power is increased by the predetermined value α from the initial value IP.
This case is shown in FIG. This is a case where the jitter value (RCP0) is in the range of 12% to 15% when the adjustment data is first recorded as the recording laser power PWw = PWw1 (initial value IP), as shown in the figure. In this case, it is determined that the recording laser power PWw is slightly insufficient at the initial value IP. Therefore, the value of the recording laser power PWw is increased by + α to PWw2. As a result, it is predicted that the jitter value will be 12% or less. Therefore, writing is performed again with the recording laser power PWw = PWw2 (= IP + α), and the processing of FIG. 7 is terminated.
Note that, since the laser power PWw2 is used, the jitter value does not necessarily have to be 12% or less. This is because by increasing at least + α, the recording laser power is more suitable than the initial value IP for subsequent focus bias / spherical aberration adjustment. Therefore, it is not necessary to confirm the jitter value after step F107.
[0077]
Further, as the case of (2), the case where the recording laser power PWw as the initial initial value IP is at a level like PWw1 ′ shown in FIG. The jitter value (RCP0) of the adjustment data recorded with this recording laser power PWw1 ′ is also in the range of 12% to 15%. In this case, if the value of the recording laser power PWw is increased by + α and PWw2 ′, the jitter value deteriorates. However, as will be described later, in order to adjust the focus bias / spherical aberration, the higher the laser power PW at the time of recording the adjustment data, the better. In such a case, the processing is finished in steps F106 and F107. Is not a problem.
[0078]
If Lim1 <RCP0 ≦ Lim2 is not satisfied in step F105, the processing of the system controller 60 proceeds to step F108, and the recording laser power PWw is changed to the initial value IP + α. In step F109, the adjustment data is written again.
In step F110, the written adjustment data is reproduced and a jitter value is acquired. The system controller 60 holds the jitter value supplied from the evaluation value calculator 35 as a variable RCP1.
[0079]
In step F111, the current jitter value (RCP1) is compared with a predetermined value Lim1. If RCP1 ≦ Lim1, the process of FIG. 7 is finished as shown in (3).
This case will be described with reference to FIG.
In this case, as shown in the figure, when the adjustment data is first recorded with the recording laser power PWw = PWw1 (initial value IP), the jitter value (RCP0) exceeds 15%, and thereafter the recording laser power PWw This is a case where the jitter value (RCP1) becomes 12% or less by increasing the value by + α to PWw2.
The jitter value RCP1 of 12% or less indicates that the recording laser power PWw at the time of the second adjustment data recording performed in step F109 was at an appropriate level. Assuming that the adjustment data for adjusting the focus bias / spherical aberration is recorded with an appropriate laser power, the adjustment data writing and the rough OPC processing are finished.
[0080]
If RCP1 ≦ Lim1 is not satisfied in step F111, the process proceeds to step F112, and it is determined whether or not the jitter value (RCP1) is equal to or smaller than a predetermined value Lim2 (for example, 15%), that is, whether Lim1 <RCP1 ≦ Lim2. Determine.
If Lim1 <RCP1 ≦ Lim2, the process proceeds to step F114 as indicated by (4), and the recording laser power PWw is changed to the initial value IP + 2α. In step F115, the adjustment data is written again, and the process of FIG. 7 is completed. That is, the adjustment data is written in a state where the value of the recording laser power is increased by 2α from the initial value IP, and the process is completed.
This case is shown in FIG. This is a case where the jitter value (RCP0) exceeds 15% when the adjustment data is first recorded as the recording laser power PWw = PWw1 (initial value IP), as shown in the figure. At this time, when the adjustment data is recorded as the recording laser power PWw = PWw2 (= IP + α) and the jitter value (RCP1) is measured in steps F108, F109, and F110, the jitter value (RCP1) is now 12-15. %. In that case, assuming that the recording laser power PWw is still insufficient, the recording laser power PWw is further increased in steps F114 and F115 to PWw3 (= IP + 2α) as shown in the figure. As a result, the jitter value is predicted to be 12% or less, that is, an appropriate laser power. That is, by increasing at least + 2α, the recording laser power is more suitable than the initial value IP for the subsequent focus bias / spherical aberration adjustment, and therefore the processing of FIG. 7 is terminated.
In this case as well, as a result of setting the laser power PWw3, the jitter value does not necessarily have to be 12% or less. Therefore, it is not necessary to check the jitter value after Step F115.
[0081]
If Lim1 <RCP1 ≦ Lim2 is not satisfied in Step F112, the process proceeds to Step F113, and the jitter values held as variables RCP0 and RCP1 are compared.
Here, when RCP0> RCP1, it is determined that the jitter is improved when laser power PWw = IP + α is set, compared with when laser power PWw = IP.
In this case, the process proceeds to step F114 as indicated by (5), and the recording laser power PWw is changed to the initial value IP + 2α. In step F115, the adjustment data is written again, and the process of FIG. 7 is completed. That is, the adjustment data is written in a state where the value of the recording laser power is increased by 2α from the initial value IP, and the process is completed.
This case is shown in FIG. This is a case where the jitter value (RCP0) exceeds 15% when the adjustment data is first recorded as the recording laser power PWw = PWw1 (initial value IP), as shown in the figure. At that time, when the adjustment data is recorded with the recording laser power PWw = PWw2 (= IP + α) and the jitter value (RCP1) is measured in steps F108, F109, and F110, the jitter value (RCP1) is again 15%. This is the case. However, since the jitter value RCP0> RCP1 and the jitter is improved by increasing the laser power PWw, it is judged that the quality of the RF signal is likely to be improved by increasing the laser power PWw, and the power is further increased by one level. The adjustment data recording is performed with the recording laser power PWw = PWw3 (= IP + 2α), and the process of FIG. 7 is terminated.
In this case as well, as a result of setting the laser power PWw3, the jitter value does not necessarily have to be 12% or less. Therefore, it is not necessary to check the jitter value after Step F115. Although there is a possibility that the value exceeds 15%, the value is improved because it is improved from the state of the initial value IP.
[0082]
If RCP0> RCP1 is not satisfied in step F113, the jitter is not improved even if the laser power PWw is increased.
Therefore, as shown by (6), the processing of FIG. 7 is finished with the laser power PWw as it is, that is, with adjustment data recording being performed with the laser power PWw = IP + α.
This case is shown in FIG. The case where RCP0 <RCP1 is satisfied is a case where the initial value IP of the recording laser power PWw is considerably high and corresponds to the upward curve of the jitter characteristic as shown in the figure. In this case, when the laser power PWw is changed from PWw1 (= IP) to PWw2 (= IP + α), the jitter value is deteriorated.
However, as described below, since there is a situation that adjustment data recording is preferably performed with as high a laser power as possible for focus bias / spherical aberration adjustment, writing is performed with the laser power PWw2 (= IP + α). The adjusted data is valid as it is.
[0083]
As described above, the adjustment data writing and the coarse OPC are performed. Here, the reason why the coarse OPC, that is, the adjustment of the recording laser power PWw is performed using the jitter value as an evaluation value will be described.
FIG. 10A shows the relationship between the adjustment accuracy (adjustment variation) of the focus bias / spherical aberration adjustment and the recording laser power PWw.
As can be seen from this figure, it is known that the adjustment variation of the focus bias / spherical aberration adjustment can be reduced as the recording laser power PWw at the time of writing the adjustment data is higher.
For example, when the limit of the laser power PWw that can output PWb in the drawing is used, at least for adjustment of the focus bias / spherical aberration, the adjustment variation is within the range from the laser power PWa at which the adjustment variation is a predetermined level th1 or less to the laser power limit PWb. It is desirable that the adjustment data is written.
That is, in the rough OPC, at least the recording laser power PWw should be set to PWa or more.
[0084]
Here, FIG. 10B shows the characteristics of the laser power PWw and the jitter value. The laser power PWa is a laser power corresponding to a region where the curve of the jitter characteristics falls to the right. Therefore, if the rough OPC is performed as described above with reference to the threshold value th2 as the jitter value, the adjustment data is written at least with the recording laser power PWw equal to or higher than PWa, that is, the focus bias / spherical surface. Adjustment data writing suitable for aberration adjustment is realized.
The threshold th2 when this jitter value is used as an evaluation value is equivalent to, for example, a jitter value of about 15%, so that rough OPC is performed based on the jitter values of 15% and 12% as described above. Preferred.
[0085]
As shown in FIG. 10A, the higher the recording laser power PWw at the time of writing the adjustment data, the better for the focus bias / spherical aberration adjustment. This is considered to be achieved by writing the adjustment data near the laser power limit value from the beginning. On the other hand, writing with too high laser power may cause deterioration of the recording layer of the disk. .
For this reason, the rough OPC is based on two concepts: “I want to write adjustment data at least at the laser power PWa” and “I don't want to make the laser power unnecessarily high”. Furthermore, even though “I don't want to make the laser power unnecessarily high”, it is not directly undesirable to write the adjustment data with a laser power close to the power limit. That is, writing with high laser power does not cause disk degradation immediately, and is never unacceptable.
Therefore, as shown in FIG.
Adjust the laser power to increase with reference to the evaluation value so that it is at least higher than a certain power value (PWa).
-When the laser power is quite high, the laser power is not lowered, and it is OK as it is.
This is the process of thinking.
[0086]
Such coarse OPC makes it possible to write appropriate adjustment data for focus bias / spherical aberration adjustment, and to guarantee the quality of signals used for focus bias / spherical aberration adjustment. Therefore, the accuracy of automatic adjustment of the focus bias / spherical aberration can be increased, and as a result, the playability of the disk drive device can be increased.
Further, adjusting the recording laser power PWw only in the direction of increasing the recording laser power PWw (if the recording laser power PWw is high) also realizes the efficiency of the rough OPC processing, as shown in FIG. 6A. It also leads to speeding up a series of processing.
[0087]
In the process of FIG. 7, the recording laser power PWw is increased from the initial value IP to a maximum of two steps (2α). However, the above-mentioned idea of “unnecessarily setting a high laser power” appears. .
However, depending on the setting of the step width α, the actual characteristics, or the settings of Lim1 and Lim2, which are threshold values, the laser power may be increased by one step at the maximum, or the laser power may be increased by three or more steps. You may be made to be. Further, the up width at the time of each laser power-up need not be a fixed width as α, and the up width may be changed as follows: IP + α at first and IP + α + β at the second time (where α ≠ β).
[0088]
In the example of FIG. 7, the RF jitter value is used as the evaluation value. However, the evaluation value may be an RF amplitude value or asymmetry.
For example, the RF amplitude value has characteristics as shown in FIG. 10C with respect to the recording laser power. Therefore, for example, the same effect can be obtained by performing rough OPC using the RF amplitude value as the evaluation value and the threshold th3 as a reference. The same applies to asymmetry.
[0089]
7). Setting range for adjustment
Next, the adjustment use range setting process as step S2 in FIG.
It is of course desirable that all the adjustment data used for focus bias / spherical aberration adjustment are under the same recording / reproducing conditions.
As the recording / reproducing condition, the presence / absence of cross-write during data writing is important.
[0090]
As is well known, tracks are spirally (or concentrically) formed from the inner circumference side to the outer circumference side, for example, and data is written along the tracks. FIG. 11 schematically shows a spiral track.
In the test writing area on the disc, the above-described adjustment data writing is performed, for example, by several rounds of track from positions P1 to P3 in FIG.
[0091]
FIG. 11B shows the image of the cross light, but the data recorded on a certain track Tr1 is affected by the recording on the adjacent track Tr2, and the data is partially overwritten. It is a phenomenon.
In the track affected by the cross light, of course, the data is not completely destroyed, but it is known that the RF signal amplitude at the time of reproduction is somewhat lowered.
Here, looking at the positions P1 to P3 in FIG. 11, in the range from the positions P1 to P2, recording of adjacent tracks on the outer peripheral side is performed after recording of each track. On the other hand, from the positions P2 to P3, that is, the last one round track for which the adjustment data has been written, no data is written to the outer track, so that no cross-write is performed.
[0092]
That is, when reproducing from the positions P1 to P3, as shown in FIG. 11C, the reproduction RF signal amplitude from the positions P1 to P2 is smaller than the reproduction RF signal amplitude from the positions P2 to P3.
This is not desirable for the focus bias / spherical aberration adjustment described later in which the RF signal amplitude, jitter value, or asymmetry is used as an evaluation value.
Therefore, in this example, the adjustment use range setting process is set so that only the portion affected by the cross light is used in the focus bias / spherical aberration adjustment.
[0093]
That is, after executing the adjustment data write, the range in which there are tracks on which data has been written on the outer peripheral side within the multiple circular track range on the disk on which the data was written is referred to as the adjustment use range. To do.
Specifically, the adjustment data writing in the process of FIG. 7 is performed between the positions P1 to P3 in FIG. 11A, and the adjustment use range setting in step S2 of FIG. In the processing, a range used for focus bias / spherical aberration adjustment is set within the range of the positions P1 and P2.
[0094]
Such adjustment use range setting can be performed by, for example, calculating an address range. For example, in the case of a Blu-ray disc, a unit called RUB (Recording Unit Block) is determined as a data writing unit in the data format.
The trial writing area is provided in a predetermined radius range on the inner circumference side of the disc. In this trial writing area, one round track corresponds to about 2 RUBs.
Further, for example, in the focus bias / spherical aberration adjustment, data having a length of 6 to 8 RUB may be present.
Therefore, as an example, the adjustment data writing is performed in the section from the position P1 to 12RUB. On the other hand, as the adjustment use range setting process, the section in the position P1 to 9RUB is considered.
In this case, the position where the recording from the position P1 to 9RUB is completed is the position before the position P2 in FIG. That is, the positions where the recording of the 9th RUB from the position P1 is completed are all within the range affected by the cross-write due to the recording of the outer track. For example, in this way, the address of the position P1 and the address of the position where the recording from the position P1 to 9RUB is completed are calculated, and this address range is set as a range to be reproduced for focus bias / spherical aberration adjustment.
[0095]
Of course, it is not necessary to use a 9RUB section. At least the address length range necessary for adjusting the focus bias / spherical aberration may be set.
Further, the position P1 where the adjustment data writing is not necessarily required to be included. That is, in FIG. 11A, a section having a required address length may be set as the adjustment use range within the range of the positions P1 and P2.
Also, for example, if focus bias / spherical aberration adjustment is possible in one round (about 2 RUB section), the adjustment use range is set within the range of positions P2 to P3 (range not affected by cross light). May be.
[0096]
Incidentally, in this case, the section affected by the cross-write is the section in which data writing is performed on the adjacent track on the outer peripheral side. However, the format is such that data writing is performed from the outer peripheral side of the disk toward the inner peripheral side. In this case, on the contrary, it goes without saying that the section in which data is written to the inner peripheral side adjacent track is the section affected by the cross write.
[0097]
8). Spherical aberration and focus bias adjustment
In step S3 of FIG. 6A or step S11 of FIG. 6B, focus bias / spherical aberration adjustment is performed. In this example, focus bias adjustment and spherical aberration adjustment are performed simultaneously.
[0098]
As described with reference to FIGS. 17 and 18, the focus bias adjustment and the spherical aberration adjustment that have been conventionally performed cannot be adjusted to the maximum margin accurately, and the adjustment time is increased if the number of samplings is increased to avoid this. It is necessary to simultaneously perform the focus bias / spherical aberration adjustment. However, in this case, the problem of the adjustment accuracy described above remains.
[0099]
So in this example,
-Adjust focus bias / spherical aberration simultaneously
・ Prevents deterioration of adjustment accuracy due to the small number of samplings and shortens the time required for adjustment
-RF signal amplitude value, etc. is used as an evaluation value, but it can be adjusted to the margin center even when the maximum amplitude is deviated from the center of the margin.
From this point of view, spherical aberration and focus bias adjustment described below are performed.
[0100]
The spherical aberration and focus bias adjustment processing of this example will be described below with reference to FIGS.
FIGS. 12 and 13 show control processing examples of the system controller 60 executed as step S3 (or step S11) in FIG.
In this example, a case where the expander 87 shown in FIG. 2 is provided as a spherical aberration correction mechanism will be described.
[0101]
When performing spherical aberration and focus bias adjustment, the system controller 60 first sets the expander 87 to the initial position as step F201 in FIG. That is, the setting control unit 17 in the servo circuit 61 of FIG. 4 is instructed to set the spherical aberration correction value setting unit 20 to the initial position, and the expander 87 is set to the initial position. Also in the subsequent processing, when the expander 87 is driven, the expander position is similarly instructed to the setting control unit 17.
In FIG. 12 and FIG. 13, “EXP” is a variable indicating a relative position from the initial position of the expander 87, and this may be considered as a spherical aberration correction value.
Setting the initial position in step F201 is a process of giving an instruction that EXP = 0 to the setting control unit 17 of the servo circuit 61.
[0102]
Next, in step F202, the system controller 60 moves the expander 87 by one step in the + direction from the initial position (instructed as EXP = 1). In this state, the adjustment data reproduction operation is executed, and the RF signal amplitude value is acquired.
That is, for the adjustment data written in the trial writing area of the disc 1 as described above, the reproduction of the address range set in the adjustment use range setting process is controlled. At that time, an RF signal amplitude value calculated as an evaluation value by the evaluation value calculation unit 35 of FIG. 5 is taken in.
The system controller 60 holds the RF amplitude evaluation value taken in this case as a variable RFa.
[0103]
Next, in step F203, the expander 87 is moved one step in the-direction from the initial position (instructed as EXP = -1). In this state, the adjustment data reproduction operation is executed in the same manner to acquire the RF signal amplitude value.
The system controller 60 holds the RF amplitude evaluation value acquired in this case as a variable RFb.
[0104]
FIG. 14A shows the processing so far as (1) and (2). FIG. 14 shows characteristics of the position of the expander 87 (EXP value) and the RF signal amplitude value (RF amplitude evaluation value).
First, EXP = 0 is set at the initial step F201, and the expander 87 is set to the initial position. Then, at step F202, the position is set at EXP = 1 as shown by (1). The RF amplitude evaluation value acquired in this state is held as RFa.
In step F202, EXP = -1 is set as indicated by (2). The RF amplitude evaluation value acquired in this state is held as RFb.
[0105]
Subsequently, in step F204 of FIG. 12, the RF amplitude evaluation values (RF1, RF2) acquired in steps F202 and F203 are compared. If RFa> RFb, the movement direction control variable DIR is set to “+1” in step F205. To do. If RFa> RFb is not satisfied, the moving direction control variable DIR is set to “−1” in step F206.
In step F207, the expander 87 is returned to the initial position (EXP = 0), and the process proceeds to steps F208 and F209.
[0106]
In step F208, first, the expander 87 is moved by one step in the direction determined by the movement direction control variable DIR. That is, the movement of the expander 87 is instructed as EXP = EXP + DIR.
Then, the focus calibration is executed in the position state of the expanded expander 87.
The focus calibration is to automatically adjust the focus bias while fixing the position of the expander 87. That is, the instruction control unit 17 of the servo circuit 61 in FIG. 4 is instructed to sequentially change the focus bias value, and the reproduction of the address range set in the adjustment use range setting process is executed to correspond to each focus bias value. Then, the RF amplitude evaluation value obtained by the evaluation value calculation unit 35 is captured. Then, the maximum value (maximum RF signal amplitude value) is found among the RF amplitude evaluation values corresponding to each of the captured focus bias values, and the maximum RF signal amplitude value is the RF amplitude when the focus calibration is performed. The evaluation value.
The system controller 60 holds this maximum RF amplitude evaluation value as a variable RF (EXP).
[0107]
In step F209, the evaluation value, that is, the value of the variable RF (EXP) as the RF amplitude evaluation value obtained by performing the focus calibration with the position of the expander 87 fixed, decreases continuously twice, and at that time It is confirmed whether or not the value of the variable RF (EXP) is equal to or less than the maximum RF amplitude value × 0.9.
If this condition is not satisfied, the process returns to step F208. If this condition is satisfied, the process proceeds to step F210.
Note that “twice” under the condition of two consecutive reductions and “0.9” under the condition of maximum RF amplitude value × 0.9 or less are examples, and may be other than this.
In step F210, the EXP value at that time is substituted for the variable i, and the amplitude value RFi is set to the value of RF (i), that is, the value of RF (EXP) at that time.
[0108]
The processing in steps F208 to F210 corresponds to the operation indicated by (3) in FIG.
That is, in the example of FIG. 14A, the amplitude values RFa and RFb obtained by the operations (1) and (2) are such that RFa> RFb. Therefore, the movement direction control variable DIR is set to “+1” in step F205.
Therefore, in step F208, first, EXP = EXP + DIR is set, and the expander 87 is moved by one step in the + direction from the initial position, so that EXP = 1 in FIG.
Focus calibration is performed in the position state of the expander 87, and the RF amplitude evaluation value obtained thereon is held as RF (EXP) = RF (1).
[0109]
At this time, since the condition of step F209 is not satisfied, EXP = EXP + DIR is set again in step F208, and the expander 87 is now in the position state of EXP = 2 in FIG. Similarly, focus calibration is performed, and the RF amplitude evaluation value obtained thereon is held as RF (EXP) = RF (2).
Further, similarly, the position is moved to each position state of EXP = 3, 4, and 5, and the focus calibration and the RF amplitude evaluation value are respectively acquired.
When EXP = 5, the condition that the RF amplitude evaluation value continuously decreases twice and becomes the RF maximum value RFMAX × 0.9 or less is satisfied.
At this time, in step F210, assuming that the point i as the position of the expander 87 is found, the variable i = EXP, that is, in this case, the point i = 5 and the RF amplitude evaluation value RF (EXP) = RF at that time is set. (5) The value held as RF (i) is the RF amplitude value RFi at point i.
[0110]
Here, the point i corresponds to the position in the + direction of the expander 87 at which the RF amplitude value becomes the lower limit (margin limit) of the allowable range.
In the example of FIG. 14A, since DIR = “+ 1” is set in step F205, the point i is found as the position in the + direction of the expander 87. However, if DIR = “ When “−1” is set, the expander 87 performs the same process while sequentially moving in the − direction, and the point i is found as a certain position in the − direction.
[0111]
When the point i as one margin limit is found in step F210 of FIG. 12, subsequently, the process of finding the point ii as the other margin limit is performed in steps F211 to F219 of FIG.
First, in step F211, the expander 87 is returned to the initial position (EXP = 0), and focus calibration is executed in the expected position state. The maximum RF amplitude evaluation value obtained in the focus calibration is held as the RF amplitude value RF (0) at the initial position.
[0112]
In step F212, the amplitude value RFi at the point i is compared with the amplitude value RF (0) at the initial position. If RF (0)> RFi, the moving direction control variable DIR is set to DIR × (−1) in step F213. That is, if DIR = “+ 1” until then, DIR = “− 1”, and if DIR = “− 1” until then, DIR = “+ 1”.
[0113]
Then, the process proceeds to Step F214. In step F214, first, the expander 87 is moved by one step in the direction determined by the movement direction control variable DIR. That is, the movement of the expander 87 is instructed as EXP = EXP + DIR.
Then, the focus calibration is executed in the position state of the expanded expander 87, and the maximum RF amplitude evaluation value obtained by the focus calibration is held as a variable RF (EXP).
[0114]
In step F215, the evaluation value, that is, the value of the variable RF (EXP) as the RF amplitude evaluation value obtained by performing the focus calibration with the position of the expander 87 fixed at a certain position in step F214 is It is confirmed whether or not the value is smaller than the amplitude value RFi.
If this condition is not satisfied, the process returns to step F214. If this condition is satisfied, the process proceeds to step F219.
When the condition is satisfied and the process proceeds to step F219, the EXP value at that time is substituted into the variable ii, and the amplitude value RFii is set to the value of RF (ii), that is, the value of RF (EXP) at that time. .
[0115]
The processing in steps F214 to F219 corresponds to the operation indicated by (4) in FIG.
That is, in the case of the example of FIG. 14, RF (0)> RFi in step F212, and the value of DIR is inverted to “−1” in step F213. Therefore, in step F214, EXP = EXP + DIR is first set. Thus, the expander 87 is moved by one step in the − direction from the initial position, and becomes the position state of EXP = −1 in FIG.
Focus calibration is performed in the position state of the expander 87, and the RF amplitude evaluation value obtained thereon is held as RF (EXP) = RF (-1).
[0116]
At this time, since the condition of step F215 is not satisfied, EXP = EXP + DIR is set again in step F214, and the expander 87 is now in the position state of EXP = −2 in FIG. 14B. Similarly, focus calibration is performed, and the RF amplitude evaluation value obtained thereon is held as RF (EXP) = RF (−2).
In this case, similarly, when the focus calibration and the acquisition of the RF amplitude evaluation value are performed by moving to the position state of EXP = −3, the amplitude value RF (EXP) = RF (−3) becomes the point i. And the condition of step F215 is satisfied.
At this time, in step F219, assuming that the point ii as the position of the expander 87 is found, the variable ii = EXP, that is, in this case, the point ii = −3, and the RF amplitude evaluation value RF (EXP) = The value held as RF (−3) = RF (ii) is the RF amplitude value RFii at point ii.
[0117]
Here, the point ii corresponds to the position of the expander 87 where the RF amplitude value is in the allowable range lower limit (margin limit) in the reverse direction to the point i found in step F210.
That is, the range of points i to ii is a spherical aberration correction value range in which the RF amplitude value is within an allowable range.
[0118]
If RF (0)> RFi is not satisfied in step F212, the moving direction control variable DIR is not changed as it is in step F216. In steps F217 and F218, processing similar to that in steps F214 and F215 is performed to search for point ii.
This is processing in the case as shown in FIG.
For example, when the initial position (EXP = 0) of the expander 87 becomes a position as shown in FIG. 15 in terms of the characteristics with the RF amplitude value, first, the expander 87 is moved in the + direction as indicated by (3). Point i is searched while moving. In this case, since RF (0) <RFi in step F212, the DIR value remains “+1” in step F216, and in steps F217 and F218, the expander 87 is also moved in the + direction from the initial position. Point ii will be searched. For example, point ii is found as a position where EXP = 1.
[0119]
However, in this case, since the process of searching for the point ii while moving in the direction in which the RF amplitude value increases, the condition in step F218 and the condition for determining the clogged point ii are the position of the expander 87 in step F217. The value of the variable RF (EXP) as the RF amplitude evaluation value obtained by performing the focus calibration while being fixed to be larger than the amplitude value RFi at the point i. That is, it is the reverse of the case of step F215.
[0120]
When the point ii is found by such processing of steps F211 to F219, the point iii, that is, the adjustment point is calculated in step F220.
This is an intermediate position between point i and point ii (iii = (i + ii) / 2).
In step F221, the expander 87 is moved to the point iii, which becomes the final adjustment position for spherical aberration adjustment, and focus calibration is executed at that position, so that the focus at the maximum amplitude value is obtained. Let the bias value be the final focus bias value by adjustment.
[0121]
The spherical aberration and focus bias adjustment are completed by the above processing.
In this case, for example, as shown in (5) of FIG. 14B, the position of the expander 87 is set to a position of EXP = 1 as a point iii that is an intermediate position between the points i and ii. This position is the point at which the margin width becomes maximum as can be seen from the figure.
Further, as can be seen from the above description, the focus calibration is executed in the position state of each expander 87 at the time of each search of the points i and ii. That is, the points i and ii that are the marginal limit points are searched using the RF amplitude value when the focus bias is adjusted in each expander position state.
This means that the focus bias adjustment and the spherical aberration adjustment are simultaneously adjusted in the direction of the axis J in FIG.
Accordingly, the point iii is the spherical aberration position of q0 in FIG. 16, and the focus bias value subjected to focus calibration at the point iii is a bias value as f0 in FIG. That is, appropriate adjustment is realized.
[0122]
In this example, focus bias / spherical aberration adjustment is performed as described above.
That is, while changing both the focus bias value and the spherical aberration correction value, two allowable limit points (points i and ii) having substantially the same evaluation value are searched for as the allowable limit points of the evaluation value. The focus bias value and the spherical aberration correction value are adjusted so as to correspond to the intermediate point (point iii) of the limit point.
When searching for two allowable limit points (points i and ii), the spherical aberration correction value is changed step by step, and the focus bias is changed at each step (focus calibration) to obtain an optimum evaluation value. To get.
[0123]
More specifically, the reproduction of the disk 1 is performed with both the focus bias value and the spherical aberration correction value changed, and at this time, the evaluation value is generated from the signal based on the reflected light, and the evaluation value is used. The process for determining the permissible limit point (points i, ii), the process for determining the intermediate point (point iii) from the two permissible limit points (points i, ii) having substantially the same evaluation value, and the intermediate point A process of adjusting the focus bias value and the spherical aberration correction value is performed so as to correspond to (point iii).
[0124]
By adjusting the focus bias / spherical aberration, the following effects can be obtained.
First, since the focus bias / spherical aberration adjustment is simultaneously performed as described above, the focus bias value and the spherical aberration correction value can be adjusted with high accuracy, respectively.
Further, since the adjustment is not performed simply to the RF amplitude maximum point but to the margin center point, the problem described with reference to FIG. 17 is avoided and appropriate adjustment is realized. As a result, the reliability of the disk drive device can be improved.
Further, since it is not necessary to increase the number of samplings of the RF amplitude evaluation value, the time required for adjustment can be shortened, and the time for waiting for the user for adjustment can also be shortened.
Furthermore, since the focus bias / spherical aberration adjustment of this example is executed after the above-described rough OPC and adjustment use range setting are performed, the adjustment accuracy is also improved in this respect.
[0125]
Various modifications can be considered for the focus bias / spherical aberration adjustment processing.
First, in the above example, focus calibration is executed each time while the position of the expander 87 is changed. On the other hand, when the focus bias value is changed stepwise, a method of calibrating the spherical aberration and searching for the points i and ii each time can be considered.
Further, although the spherical aberration adjustment mechanism is an example of a mechanism by the expander 87, it is of course possible to adopt a mechanism using the liquid crystal panel 89 of FIG.
In that case, a process for searching for points i and ii by performing focus calibration while changing the spherical aberration correction value stepwise in the liquid crystal panel 89, or while changing the focus bias value stepwise, The process shown in FIGS. 12 and 13 may be performed by performing the process of searching for the points i and ii by calibrating the spherical aberration each time.
[0126]
By the way, in the case of the configuration using the expander 87, if a method of calibrating the spherical aberration and searching for the points i and ii each time while changing the focus bias value stepwise, the adjustment time is as shown in FIG. , Longer than the case described in FIG. This is because the number of mechanical movements of the expander 87 increases. Therefore, in the case of a configuration using the expander 87, the processing described with reference to FIGS. 12 and 13 is preferable in terms of required time.
On the other hand, in the case of the configuration using the liquid crystal panel 89, the focus bias value is also set in the process of searching for the points i and ii by performing the focus calibration while gradually changing the spherical aberration correction value in the liquid crystal panel 89. Even in the case where the process of searching for the points i and ii by performing calibration of the spherical aberration each time while changing in stages, no mechanical movement occurs, so there is no great difference in time. In addition, the fact that mechanical movement is not required also makes it possible to adjust the focus bias / spherical aberration more quickly than the configuration using the expander 87.
[0127]
In the above example, the RF amplitude value is used as the evaluation value when adjusting the focus bias / spherical aberration, but a jitter value or asymmetry may be used.
Furthermore, even an unrecorded portion where a reproduction RF signal cannot be obtained on the disc can be adjusted using the amplitude component due to the wobble of the groove. In that case, rough OPC and adjustment use range setting processing are not required.
Further, when the disk 1 is a reproduction-only disk, the above-described focus bias / spherical aberration adjustment process and the process described as a modification thereof are also effective.
[0128]
9. Adjustment timing
Various timings for executing the series of adjustment processes shown in FIG. 6A or 6B can be considered.
First, of course, it is appropriate to execute it when the disc is loaded.
It is also conceivable to execute during playback, before and after seek, or after a predetermined time has elapsed, or according to the trace position (inner and outer periphery) on the disk.
For example, during reproduction, the data read from the disk 1 can be performed at a timing with sufficient margin for buffering.
In addition, the timing immediately before or after the seek is also suitable as the execution timing of the adjustment process.
[0129]
Also, by adjusting according to the temperature state of the device (change in the focus bias optimum value due to the temperature characteristics of the device and actuator), aging, and the trace position (radius position) on the disk, adjustments corresponding to these circumstances State and can.
Therefore, even during the operation period with respect to the disk 1, the adjustment processing is executed regularly or irregularly, which is appropriate for stabilizing the operation of the apparatus. It is also conceivable that adjustment processing is performed using temperature change detection, reproduction data error rate / jitter deterioration, etc. as triggers.
[0130]
【The invention's effect】
As can be understood from the above description, according to the present invention, two allowable limit points at which the evaluation values are substantially equivalent as the allowable limit points of the evaluation value while changing both the focus bias value and the spherical aberration correction value. The focus bias value and the spherical aberration correction value are adjusted so as to correspond to an intermediate point between the two allowable limit points. In this case, since the focus bias / spherical aberration adjustment is performed simultaneously, it is possible to accurately adjust the focus bias value and the spherical aberration correction value, respectively.
In addition, the adjustment is not performed simply to the RF amplitude maximum point but to the margin center point, so that the optimum adjustment can be performed with high accuracy. As a result, the reliability of the disk drive device can be improved.
In this case, since it is not necessary to increase the number of evaluation value samplings, the time required for the adjustment can be shortened, and the time for the user to wait for the adjustment can also be shortened.
When searching for two allowable limit points (points i and ii), one of the focus bias value and the spherical aberration correction value is changed stepwise, and the other is changed at each step to obtain an optimum evaluation value. By performing the process of acquiring the above, the above simultaneous adjustment process can be appropriately executed.
[0131]
In addition, setting the range used for adjusting the focus bias and the spherical aberration within the range where the data writing used for the adjustment process for the focus bias and the spherical aberration is executed, uses the range of the same condition during the adjustment. It means to do. This also contributes to improving the accuracy of focus bias / spherical aberration adjustment to be performed thereafter.
In particular, within the range in which data writing is performed in a plurality of round track ranges from the inner circumference side to the outer circumference side, the range where the track on which the data writing has been performed on the outer circumference side is used as the adjustment use range, The focus bias / spherical aberration adjustment can be executed within the range where the cross light conditions are the same, which is suitable for improving the accuracy.
[Brief description of the drawings]
FIG. 1 is a block diagram of a disk drive device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of an example of a spherical aberration correction mechanism according to the embodiment.
FIG. 3 is an explanatory diagram of an example of a spherical aberration correction mechanism according to the embodiment.
FIG. 4 is a block diagram of a main part of the servo circuit according to the embodiment.
FIG. 5 is a block diagram of a reader / writer circuit according to the embodiment.
FIG. 6 is a flowchart of an adjustment processing procedure according to the embodiment.
FIG. 7 is a flowchart of adjustment data writing and rough OPC processing according to the embodiment;
FIG. 8 is an explanatory diagram in the case of (1), (2), and (3) in the adjustment data writing and coarse OPC processing of FIG.
FIG. 9 is an explanatory diagram for the case of (4), (5), and (6) in the adjustment data writing and coarse OPC processing of FIG. 7;
FIG. 10 is an explanatory diagram of evaluation values for adjustment data writing and rough OPC processing according to the embodiment;
FIG. 11 is an explanatory diagram of adjustment usage range setting according to the embodiment;
FIG. 12 is a flowchart of spherical aberration and focus bias adjustment according to the embodiment.
FIG. 13 is a flowchart of spherical aberration and focus bias adjustment according to the embodiment.
FIG. 14 is an explanatory diagram of spherical aberration and focus bias adjustment operations of the embodiment.
FIG. 15 is an explanatory diagram of spherical aberration and focus bias adjustment operations according to the embodiment.
FIG. 16 is an explanatory diagram of simultaneous adjustment of spherical aberration and focus bias according to the embodiment.
FIG. 17 is an explanatory diagram of problems of spherical aberration and focus bias adjustment.
FIG. 18 is an explanatory diagram of the necessity of simultaneous adjustment of spherical aberration and focus bias.
[Explanation of symbols]
1 disk, 10 DSP, 11, 21 A / D converter, 12 focus servo calculation unit, 13, 23, 25 D / A converter, 14 focus driver, 15 adder, 16 focus bias setting unit, 17 setting control unit , 18 Non-volatile memory, 20 Spherical aberration correction value setting unit, 22 Tracking servo calculation unit, 24 Tracking driver, 26 Spherical aberration correction driver,
31 Write waveform generation unit, 32 binarization circuit, 33 RF reproduction processing unit, 34 PLL circuit, 35 evaluation value calculation unit, 51 pickup, 52 spindle motor, 53 thread mechanism, 54 matrix circuit, 55 reader / writer circuit, 56 Modulation / demodulation circuit, 57 ECC encoder / decoder, 58 wobble circuit, 59 address decoder, 60 system controller, 61 servo circuit, 62 spindle servo circuit, 63 laser driver, 87 expander, 89 liquid crystal panel, 120 AV system

Claims (6)

For writing or reading data, laser irradiation and reflected light detection with respect to the disk recording medium, a laser beam focus servo mechanism, and head means having a spherical aberration correction mechanism,
Evaluation value generating means for generating an evaluation value from a signal based on reflected light obtained by the head means;
Focus servo means for driving the focus servo mechanism based on a focus error signal generated as a signal based on reflected light obtained by the head means to execute focus servo;
Spherical aberration adjustment means for performing spherical aberration adjustment by driving the spherical aberration correction mechanism based on a spherical aberration correction value;
A focus bias means for adding a focus bias to a focus loop including the focus servo means;
While changing both the focus bias value and the spherical aberration correction value, two allowable limit points at which the evaluation values are substantially equal are searched as the allowable limit points of the evaluation value, and the two allowable limit points are searched. Control means for adjusting the focus bias value and the spherical aberration correction value so as to correspond to an intermediate point;
The disk recording medium in which the data writing used for the adjustment process of the focus bias and the spherical aberration is performed on the disk recording medium in a plurality of circular track ranges from the inner circumference side to the outer circumference side. In the upper range, the adjustment use range to be reproduced during the adjustment process of the focus bias and the spherical aberration is within the multi-turn track range, and the track on which the data writing has been performed on the outer peripheral side. A disk drive device comprising : an adjustment use range setting means for setting the adjustment use range within an existing range .   2. The disk drive according to claim 1, wherein the evaluation value generating means generates a jitter value, a reproduction signal amplitude value, or an asymmetry value as the evaluation value when reproducing data from the disk recording medium. apparatus.   When searching for the permissible limit point, the control means changes one of the focus bias value and the spherical aberration correction value in stages, and changes the other in each stage to perform the optimal evaluation. 2. The disk drive device according to claim 1, wherein processing for acquiring a value is performed. An evaluation value generating step of reproducing the disk recording medium in a state where both the focus bias value and the spherical aberration correction value are changed, and generating an evaluation value from a signal based on the reflected light at that time,
An allowable limit point determining step for determining an allowable limit point based on the evaluation value;
An intermediate point determining step for determining an intermediate point between the two allowable limit points from the two allowable limit points determined in the allowable limit point determining step, the evaluation values being substantially equal;
An adjustment step of adjusting the focus bias value and the spherical aberration correction value so as to correspond to the intermediate point ,
In the adjustment step, data writing used for adjusting the focus bias and the spherical aberration is performed on the disk recording medium from the inner circumference side to the outer circumference side in a plurality of round track ranges, and then the data writing is performed. Within the range on the disc recording medium that has been performed, the adjustment use range to be reproduced during the adjustment process of the focus bias and the spherical aberration is within the multi-round track range, and the data writing is performed on the outer peripheral side. A focus bias and spherical aberration adjustment method, comprising : an adjustment use range setting step for setting the adjustment use range within a range in which a track is performed . 5. The focus bias and spherical aberration adjustment method according to claim 4 , wherein in the evaluation value generating step, a jitter value, a reproduction signal amplitude value, or an asymmetry value is generated as the evaluation value. In the allowable limit point determination step, one of the focus bias value and the spherical aberration correction value is changed stepwise, and at each step, the other is changed to obtain the optimum evaluation value. The focus bias and spherical aberration adjustment method according to claim 4 .

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