JP4154962B2 - 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 method.
[0002]
[Prior art]
[Patent Document 1]
JP 2000-242937 A
  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 DVR (Data & Video Recording) has been developed, and the capacity has been significantly increased.
[0003]
For high-density discs such as DVR, in a disc structure having a cover layer of 0.1 mm in the disc thickness direction, a combination of a laser having a wavelength of 405 nm (so-called blue laser) and an objective lens having an NA of 0.85 is used. When recording / reproducing a phase change mark (phase change mark), the format efficiency is about 82% using a data block of 64 KB (kilobytes) with a track pitch of 0.32 μm and a linear density of 0.12 μm / bit as one recording / reproducing unit As a result, a capacity of about 23.3 GB (gigabytes) can be recorded and reproduced on a direct 12 cm disc.
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.
[0004]
[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.
[0005]
In particular, in the case of a high-density disk such as the above-mentioned DVR, it is necessary to correct spherical aberration in order to cope with a cover layer thickness error or a multilayered recording layer. A device having a spherical aberration correction mechanism using a liquid crystal element has been developed.
[0006]
Conventionally, there has been a technique for setting a focus bias using an RF signal or a tracking error signal in a disk drive device. However, in a system having a spherical aberration correction mechanism, a method for adjusting a focus bias and a spherical aberration correction value is known. Not.
In an optical disk recording / reproducing apparatus that employs a high numerical aperture and blue laser, it is guaranteed that the RF signal can be recorded / reproduced when the focus bias and spherical aberration correction values are not adjusted or at a predetermined constant value determined by design. There is no.
For this reason, before the focus bias adjustment and the spherical aberration correction value adjustment using the RF signal, it is necessary to first make the RF signal ready for recording and reproduction.
[0007]
[Means for Solving the Problems]
Therefore, the present invention adjusts the focus bias and the spherical aberration correction value so that the tracking error signal amplitude is optimal with the focus servo turned on and the tracking servo turned off, such as when a disc is inserted or during recording / playback. Accordingly, it is an object to obtain a focus bias and a spherical aberration correction value having sufficient recording / reproduction characteristics for various adjustments using at least an RF signal.
[0008]
For this purpose, the disk drive device of the present invention performs laser irradiation and reflected light detection on a disk recording medium for data writing or reading, as well as laser beam focus servo mechanism, tracking servo mechanism, and spherical aberration correction. A head means having a mechanism; an error signal generating means for generating a focus error signal and a tracking error signal from reflected light obtained by the head means; a focus servo drive signal is generated based on the focus error signal; and the focus servo Focus servo means for driving the mechanism to perform focus servo, tracking servo means for generating a tracking servo drive signal based on the tracking error signal, driving the tracking servo mechanism to execute tracking servo, and spherical aberration A spherical aberration correction drive unit that generates a spherical aberration correction drive signal based on a positive value, drives the spherical aberration correction mechanism to perform spherical aberration correction, and a focus that adds a focus bias to the focus loop including the focus servo unit A focus bias value that is detected by the bias means and the tracking bias signal while the optimum value of the focus bias and the spherical aberration correction value are detected and added by the focus bias means, and the spherical aberration correction means And adjusting means for setting the spherical aberration correction values to optimum values.
[0009]
More specifically, the adjusting means sets the focus bias added by the focus bias means to a predetermined value, observes the tracking error signal while changing the spherical aberration correction value, and observes the observed tracking. After detecting the optimal spherical aberration correction value based on the amplitude of the error signal, set the optimal spherical aberration correction value in the spherical aberration correction means, observe the tracking error signal while changing the focus bias value, An optimum focus bias value is detected based on the observed tracking error signal amplitude, and the focus bias added by the focus bias means is set to the optimum focus bias value. Alternatively, the adjustment means sets the spherical aberration correction value in the spherical aberration correction means to a predetermined value, observes the tracking error signal while changing the focus bias value, and based on the observed amplitude of the tracking error signal After detecting the optimum focus bias value, set the optimum focus bias value for the focus bias means, observe the tracking error signal while changing the spherical aberration correction value, and adjust the amplitude of the observed tracking error signal. Based on this, an optimal spherical aberration correction value is detected, and the spherical aberration correction value in the spherical aberration correction means is set to the optimal spherical aberration correction value.
[0010]
The adjusting unit stores the detected optimum value of the focus bias and the optimum value of the spherical aberration correction value in the storing unit.
When the storage means is provided, the adjusting means observes the tracking error signal while changing the spherical aberration correction value, and detects an optimum spherical aberration correction value based on the amplitude of the observed tracking error signal. The focus bias value added by the focus bias means is set to the value stored in the storage means.
When the storage means is provided, the adjusting means observes the tracking error signal while changing the focus bias value, and detects an optimum focus bias value based on the amplitude of the observed tracking error signal. The spherical aberration correction value in the spherical aberration correction means is set to a value stored in the storage means.
[0011]
The adjusting means sets a focus bias to be added by the focus bias means, observes the tracking error signal while changing a spherical aberration correction value, and selects an appropriate spherical surface based on the amplitude of the observed tracking error signal. A process for detecting an aberration correction value and a spherical aberration correction value in the spherical aberration correction means are set, and the tracking error signal is observed while changing the focus bias value. Based on the observed tracking error signal amplitude The process of detecting an appropriate focus bias value is alternately repeated to detect the optimum focus bias value and spherical aberration correction value.
[0012]
In addition, when the detected optimum value of the focus bias or the optimum value of the detected spherical aberration correction value is a value that does not fall within the predetermined range, the adjusting means sets the detection result as an error.
In addition, the adjusting means stores the optimum value of the detected focus bias and the optimum value of the spherical aberration correction value in the storage means, and the optimum value of the detected focus bias or the detected spherical aberration correction. When the detection result of the optimum value is an error, the value stored in the storage unit is applied as the optimum value of the focus bias or the optimum value of the spherical aberration correction value.
[0013]
As a specific optimum value detection operation by the adjusting means, the focus bias value or the spherical aberration correction value is changed from a predetermined value to three types at equal intervals, and the amplitude of the tracking error signal in each case is changed. The optimal value of the focus bias or the optimal value of the spherical aberration correction value is detected by a calculation process that performs quadratic curve approximation using the three measurement results.
Alternatively, the adjusting means changes the focus bias value or the spherical aberration correction value from the predetermined value to three or more at regular intervals, measures the amplitude of the tracking error signal in each case, and each measurement result The optimal value of the focus bias or the optimal value of the spherical aberration correction value is detected by a calculation process that performs quadratic curve approximation using the three measurement results selected based on the above.
Alternatively, the adjusting unit measures the amplitude of the tracking error signal while changing the focus bias value or the spherical aberration correction value from a predetermined value, and sets the value at which the amplitude of the tracking error signal is optimum to the focus bias value. Or the optimum value of the spherical aberration correction value.
[0014]
The focus bias and spherical aberration adjustment method of the present invention performs laser irradiation and reflected light detection on a disk recording medium for data writing or reading, and also includes a laser beam focus servo mechanism, tracking servo mechanism, and spherical aberration. As a method for adjusting the focus bias and spherical aberration in a disk drive device having a correction mechanism, the focus servo loop is entered while observing the tracking error signal generated from the reflected light with the focus servo on and the tracking servo off. The optimum value of the focus bias to be added and the optimum value of the spherical aberration correction value are detected, and the focus bias value to be added to the focus servo loop and the spherical aberration correction value for driving the spherical aberration correction mechanism are detected. Set to the optimum value.
[0015]
More specifically, the focus bias is set to a predetermined value, the tracking error signal is observed while changing the spherical aberration correction value, and the optimum spherical aberration correction value based on the amplitude of the observed tracking error signal Is detected, the optimal spherical aberration correction value is set, the tracking error signal is observed while changing the focus bias value, and the optimal focus bias value is detected based on the amplitude of the observed tracking error signal. The focus bias is set to the optimum focus bias value.
Alternatively, after setting the spherical aberration correction value to a predetermined value, observing the tracking error signal while changing the focus bias value, and detecting the optimum focus bias value based on the amplitude of the observed tracking error signal The tracking error signal is observed while changing the spherical aberration correction value by setting an optimum focus bias value, and the optimum spherical aberration correction value is detected based on the amplitude of the observed tracking error signal. The aberration correction value is set to the optimum spherical aberration correction value.
[0016]
The detected optimum value of the focus bias and the optimum value of the spherical aberration correction value are stored in the storage means.
In this case, when the tracking error signal is observed while changing the spherical aberration correction value and the optimum spherical aberration correction value is detected based on the amplitude of the observed tracking error signal, the focus bias value is Set to the value stored in the storage means.
Further, when the tracking error signal is observed while changing the focus bias value, and the optimum focus bias value is detected based on the amplitude of the observed tracking error signal, the spherical aberration correction value is stored in the storage means. Set to the value stored in.
[0017]
In addition, processing for setting the focus bias, observing the tracking error signal while changing the spherical aberration correction value, and detecting an appropriate spherical aberration correction value based on the amplitude of the observed tracking error signal, and the spherical surface The process of setting the aberration correction value, observing the tracking error signal while changing the focus bias value, and detecting the appropriate focus bias value based on the amplitude of the observed tracking error signal are alternately repeated. Thus, the optimum focus bias value and spherical aberration correction value are detected.
[0018]
If the detected optimum value of the focus bias or the detected optimum value of the spherical aberration correction value is a value that does not fall within the predetermined range, the detection result is regarded as an error. Further, the optimum value of the detected focus bias and the optimum value of the spherical aberration correction value are stored in the storage means, and the detection result of the detected optimum value of the focus bias or the detected spherical aberration correction value is regarded as an error. In this case, the value stored in the storage unit is applied as the optimum value of the focus bias or the optimum value of the spherical aberration correction value.
[0019]
As specific detection processing of the optimum value, the focus bias value or the spherical aberration correction value is changed from a predetermined value to three types at equal intervals, and the amplitude of the tracking error signal in each case is measured. The optimal value of the focus bias or the optimal value of the spherical aberration correction value is detected by a calculation process that performs quadratic curve approximation using two measurement results.
Alternatively, the focus bias value or the spherical aberration correction value is changed from a predetermined value to three or more in equal intervals, and the amplitude of the tracking error signal in each case is measured, and selected based on each measurement result. The optimum value of the focus bias or the optimum value of the spherical aberration correction value is detected by an arithmetic process that performs quadratic curve approximation using the three measurement results.
Alternatively, the amplitude of the tracking error signal is measured while changing the focus bias value or the spherical aberration correction value from the predetermined value, and the value at which the amplitude of the tracking error signal is optimal is set to the optimum value of the focus bias, or It is detected as the optimum value of the spherical aberration correction value.
[0020]
According to the present invention having the above configuration, the operation for finding the optimum focus bias value and the optimum spherical aberration correction value using the amplitude of the tracking error signal is executed, and the RF signal can be recorded and reproduced. Can do.
[0021]
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, and its focus bias and spherical aberration adjustment method 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). Adjustment processing example [1]
4-1 Adjustment process
4-2 Detection operation by three-point measurement method
4-3 Detection by the extended three-point measurement method
4-4 Detection by the optimum value detection method
5. Adjustment processing example [2]
6). Adjustment processing example [3]
7. Adjustment processing example [4]
8). Adjustment processing example [5]
9. Adjustment timing
10. Modified example
[0022]
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 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.
[0023]
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.
[0024]
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 (not shown) 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.
[0025]
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.
[0026]
  As will be described later, the pickup 51 is provided with a mechanism for correcting the spherical aberration of the laser light, and includes a system controller 60 and a servo circuit.61Spherical aberration correction is performed under the control.
[0027]
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 (reproduction data 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.
[0028]
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.
[0029]
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.
[0030]
  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.
  Address decoder59Generates a clock by PLL processing using a 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.
[0031]
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.
[0032]
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.
[0033]
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 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.
[0034]
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.
[0035]
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.
[0036]
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.
[0037]
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.
[0038]
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.
[0039]
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.
[0040]
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.
[0041]
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.
[0042]
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 that case, an operation unit and a display unit are provided, and the configuration of an 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.
[0043]
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.
[0044]
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 passes through collimator lenses 87 and 88 as spherical aberration correction mechanisms. It proceeds and is irradiated onto the disk 1 from the objective lens 84.
The reflected light from the disk 1 passes through the objective lens 84 and collimator lenses 88 and 87, is reflected by the beam splitter 83, and enters the detector 86 via the collimator lens (condenser lens 85).
[0045]
In such an optical system, the collimator lenses 87 and 88 have a function of changing the diameter of the laser beam. That is, the collimator lens 87 is movable in the J direction, which is the optical axis direction, so that the diameter of the laser light irradiated on the disk 1 is adjusted.
In other words, spherical aberration correction can be performed by performing control to execute a back-and-forth movement with respect to a driving unit of a collimator lens 87 (not shown).
[0046]
The example of FIG. 3A includes a liquid crystal panel 89 instead of the collimator lenses 87 and 88 of 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 drive circuit that drives the liquid crystal panel 89 so as to change the transmission region.
[0047]
3. Servo system configuration
In the servo circuit 61 in FIG. 1, a part for forming the focus servo loop and the tracking servo loop described above and a part for setting the spherical aberration correction value are shown in FIG. 4.
[0048]
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.
[0049]
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 a focus servo signal FS by performing predetermined calculations such as filtering for phase compensation and loop gain processing on the focus error signal FE input as digital data. To do. The focus servo signal FS 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 actuator. That is, the current is applied to the focus coil of the biaxial mechanism that holds the objective lens in the optical pickup 51, and the focus servo operation is executed.
[0050]
The tracking servo calculation unit 22 generates and outputs a tracking servo signal TS by performing predetermined calculations such as filtering for phase compensation and loop gain processing on the tracking error signal TE input as digital data. To do. The tracking servo signal TS 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 actuator. That is, a current is applied to the tracking coil of the biaxial mechanism that holds the objective lens in the optical pickup 51 to execute the tracking servo operation.
[0051]
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. When the focus bias setting unit 16 outputs a focus bias value detected / set by an adjustment process described later, an appropriate focus bias is added to the focus servo loop.
[0052]
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 drive power to a mechanism that moves the collimator lens 87. Further, in the case of the spherical aberration correction mechanism as shown in FIG. 3, a circuit for controlling voltage application to a required cell of the liquid crystal panel 89 is used.
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.
[0053]
The amplitude measuring unit 19 measures the amplitude of the tracking error signal TE. The amplitude measurement method basically uses envelope detection. In addition, averaging for a predetermined time, noise removal filter processing, abnormal value elimination sequence, and the like are performed as necessary. The adjustment value calculation unit 17 detects an optimum value as a focus bias value and a spherical aberration correction value by an adjustment process described later. At this time, the optimum value is detected using the amplitude measurement result of the tracking error signal TE by the amplitude measuring unit 19. Normally, the focus bias value and the spherical aberration correction value that maximize the tracking error amplitude are set to the optimum values.
The adjustment value calculation unit sets the focus bias value in the focus bias setting unit 16 and the spherical aberration correction value in the spherical aberration correction value setting unit 20 as a predetermined value for the adjustment operation or an optimum value as an adjustment result. To do.
The nonvolatile memory 18 is used as a storage area for the optimum focus bias value and spherical aberration correction value detected by the adjustment value calculator 17.
[0054]
As described above, the operations related to the adjustment of the focus servo / spherical aberration correction value, which are formed in the DSP 10, are controlled by the system controller 60.
[0055]
4). Adjustment processing example [1]
4-1 Adjustment process
Hereinafter, various examples of the focus bias and spherical aberration adjustment processing executed mainly by the processing of the servo circuit 61 having the configuration shown in FIG. 4 will be described.
First, an example of the adjustment process [1] will be described with reference to FIG. FIG. 5 shows processing executed by the DSP 10 in response to an instruction from the system controller 60.
[0056]
First, in the adjustment process, in step F101, the focus servo is turned on and the tracking servo is turned off.
In step F102, the adjustment value calculation unit 17 sets an initial value for measurement as the focus bias value in the focus bias setting unit 16. The initial value for measurement may be stored in the nonvolatile memory 18 or the like as a predetermined value, for example.
[0057]
In a state where the focus bias value is fixed at the initial value, in step F103, the amplitude value of the tracking error signal obtained from the amplitude measuring unit 19 is observed while changing the spherical aberration correction value in the spherical aberration correction value setting unit 20. Then, a process for searching for the optimum value of the spherical aberration correction value is performed.
Specific examples of this search process will be described later as examples of a three-point measurement method, an extended three-point measurement method, and an optimum value detection method.
[0058]
When the optimum value as the spherical aberration correction value can be detected by the optimum value search processing in step F103, the adjustment value calculating unit 17 uses the detected spherical aberration correction value as the spherical aberration correction value setting unit in step F104. Set to 20.
Then, in a state where the spherical aberration correction value is fixed to the optimum value, in step F105, the amplitude value of the tracking error signal obtained from the amplitude measuring unit 19 is observed while changing the focus bias value in the focus bias setting unit 16. Thus, a process for searching for the optimum value of the focus bias value is performed.
Similar to the case of the spherical aberration correction value, this search process can also be executed in each example as a later-described three-point measurement method, extended three-point measurement method, and optimum value detection method.
[0059]
If the optimum value as the focus bias value can be detected by the optimum value search process in step F105, the adjustment value calculating unit 17 sets the detected optimum value of the focus bias value in the focus bias setting unit 16 in step F106. .
[0060]
With the above processing, the spherical aberration correction value and the focus bias value are adjusted to optimum values that maximize the amplitude of the tracking error signal, for example.
This means that the focus bias and the spherical aberration correction value have been adjusted so that the RF signal can be recorded and reproduced in a disk drive device employing a high numerical aperture, blue laser.
Therefore, thereafter, the recording / reproducing operation, other adjustments such as laser power adjustment, detailed spherical aberration correction using the RF signal, focus bias correction, and the like can be appropriately executed.
[0061]
In particular, when the recording and reproduction characteristics are sufficient due to the focus bias and the spherical aberration correction value adjusted in the above adjustment process, it is not always necessary to perform the focus bias adjustment by the RF signal and the adjustment by the spherical aberration correction mechanism. In this case, the efficiency of operation is also realized.
[0062]
In addition, since the spherical aberration correction value and the focus bias value at which the amplitude of the tracking error signal is optimal can be known, for example, even when the adjustment result using the RF signal is used at the time of data recording / reproducing, the servo stability such as seek It is also possible to use a method of operating using the focus bias and the spherical aberration correction value obtained by the above process in a scene where the performance is required.
[0063]
4-2 Detection operation by three-point measurement method
A three-point measurement method will be described as an example of the search process in steps F103 and F105 of FIG. Note that the three-point measurement method, the extended three-point measurement method, and the optimum value detection method, which will be described later, can be similarly employed in the adjustment processes [2] to [5] (FIGS. 9 to 12) described later.
[0064]
For example, if the tracking error signal amplitude versus the focus bias value (or spherical aberration correction value) has a quadratic function relationship, the tracking error amplitude at three focus bias values is obtained and the optimum focus bias value (or spherical aberration) is obtained. Correction value) can be calculated.
In the following description, the focus bias is taken as an example of the parameter to be adjusted. However, the spherical aberration correction value can be adjusted using the same concept.
[0065]
FIG. 6 shows an image of adjustment by basic three-point measurement.
Decide a predetermined focus bias B, a predetermined focus bias change step A, change the focus bias to three values of BA, B, B + A, and obtain the tracking error signal amplitude value at each focus bias value To do.
The tracking error signal amplitude is approximated by drawing a quadratic curve with respect to the focus bias.
The actual tracking error signal often has a shape different from the quadratic curve as the focus bias characteristic, but if the peak point approximated by the quadratic curve is obtained, it is the point where the margin can be taken most as the actual tracking error signal curve. Since the possibility is high, this method is useful in practice.
[0066]
If the tracking error signal amplitude is Y and the focus bias is X, the relationship is expressed by using the coefficient α, X intercept β, Y intercept γ as parameters of the quadratic curve,
Y = α × (X + β)²+ γ (Formula 1)
It can be expressed by the expression.
Of the above (Formula 1), the parameter to be obtained now is β. That is, the focus bias that gives the peak of the amplitude curve of the tracking error signal is the X intercept.
[0067]
Here, as shown in FIG. 6, if the amplitude values of the tracking error signal when the focus bias is BA, B, B + A are Y (−1), Y (0), Y (+1), respectively, this amplitude Substituting each of the values Y (-1), Y (0), Y (+1) into (Equation 1) and solving for β,
β = B + 0.5 × (Y (+1) -Y (-1)) / (2 × Y (0) -Y (+1) -Y (-1)) (Expression 2)
Is obtained.
Using this (Equation 2), a focus bias value that optimizes the amplitude of the tracking error signal can be obtained.
[0068]
As described above, if the amplitude value of the tracking error signal is obtained at each of the three points as the focus bias value, and the optimum focus bias value is obtained by the calculation of (Equation 2), the optimum value of the focus bias value can be quickly obtained. Can be requested. Similarly, for the spherical aberration correction value, the tracking error signal amplitude value is obtained for each of the three spherical aberration correction values, and the optimum value can be obtained by the calculation of the above (Equation 2).
Therefore, the adjustment time is quicker than the adjustment of the focus bias and the spherical aberration correction value, and the preparation time for data recording / reproduction can be shortened.
[0069]
4-3 Detection by the extended three-point measurement method
Next, an extended three-point measurement method will be described.
The three-point measurement method described above is correct and optimal regardless of the tendency of the measured tracking error signal amplitude if the relationship between the tracking error signal amplitude and the focus bias (or spherical aberration correction value) is a nearly perfect quadratic curve. The focus bias (or spherical aberration correction value) can be calculated. However, in reality, it is often not a complete quadratic curve. Therefore, it is possible to calculate the optimum focus bias with higher accuracy by calculating at three points near the peak of the quadratic curve as much as possible.
[0070]
As an example, in FIG. 7, the tracking error signal amplitude values Y (−1), Y (0), and Y (+1) obtained at the focus bias values BA, B, and B + A tend to decrease monotonously. Shows the case.
In such a case, the focus bias is further moved by a predetermined focus bias change step A in the direction in which the tracking error increases. In other words, the amplitude Y (-2) of the tracking error signal at the point B-2A is measured as the focus bias.
At this time, when the amplitude value Y (−2) shows a decreasing tendency with respect to the amplitude value Y (−1) as in the example of FIG. 7, three consecutive points including the newly added point, that is, By using the amplitude values Y (-2), Y (-1), and Y (0) of the tracking error signal at B-2A, BA, and B, the focus bias optimum value is Can be calculated. In this case,
β = B−A + 0.5 × (Y (0) -Y (-2)) / (2 × Y (-1) -Y (0) -Y (-2)) (Equation 3)
As a result, an optimum focus bias value can be calculated.
[0071]
Unlike the example of FIG. 7, if the amplitude value Y (−2) has a further increasing tendency with respect to the amplitude value Y (−1), the amplitude value Y of the tracking error signal at the focus bias at point B-3A is further increased. (-3) is measured, and the amplitude value Y (-3) is compared with the amplitude value Y (-2). At this time, when the amplitude value Y (-3) shows a decreasing tendency with respect to the amplitude value Y (-2), three consecutive points including the newly added point, that is, B-3A, B2-A, The amplitude values Y (-3), Y (-2), and Y (-1) of the tracking error signal at BA may be used.
[0072]
Thus, in the initial three focus bias values BA, B, B + A, the tracking error signal amplitude values Y (-1), Y (0), Y (+1) tend to be monotonously decreasing. In this case, the amplitude values Y (-2), Y (-3),... Of the tracking error signal are observed with the focus bias values B-2A, B-3A,. That is, the amplitude value of the tracking error signal is measured while changing the focus bias value to three or more in equal intervals. When the tracking error signal amplitude value is observed to decrease, or when the focus bias step addition count limit reaches N times, three consecutive points B-MA and B- In (M-1) A, B- (M-2) A, the amplitude value Y (-M), Y (-(M-1)), Y (-(M-2)) of each tracking error signal Select the focus bias optimum value. That is, a generalized formula of the above (formula 2) and (formula 3),
β = B− (M-1) × A + 0.5 × (Y (-(M-2))-Y (-M))
/ (2 × Y (-(M-1))-Y (-(M-2))-Y (-M)) (Formula 4)
The optimal focus bias can be calculated according to
[0073]
In the above description, the case where the tracking error amplitude is monotonously decreased with respect to the focus bias has been described as an example.
Such an extended three-point measurement method can appropriately cope with a case where a large amount of spherical aberration occurs (when the disc cover thickness error is large).
[0074]
4-4 Detection by the optimum value detection method
In the above three-point measurement method and extended three-point measurement method, the optimal value was calculated by approximating the amplitude curve of the tracking error signal with respect to the focus bias or the spherical aberration correction value as a quadratic curve, and approximating from the three amplitude values. A direct tracking error signal amplitude peak point or a method of searching for a point where the amplitude decrease is equal can be considered.
There are several methods, but typical methods are shown below.
[0075]
<Pattern 1>
As shown in FIG. 8, B-NA, B- (N-1) A, ..., BA, B, B + A, ..., B + (N-1) A, B + NA, and focus Varying the bias value, tracking error amplitude Y (-N), Y (-N-1), ..., Y (-1), Y (0), Y (+1) in each case, ...・ Measure Y (+ N-1) and Y (+ N).
Then, the focus bias value when the amplitude of the tracking error signal is maximum is optimized.
[0076]
<Pattern 2>
Move the focus bias value with B-NA, B- (N-1) A, ..., measure the tracking error amplitude in each case, and when the amplitude trend of the past L times reverses from rising to falling The inflection point is set as the optimum focus bias value.
[0077]
<Pattern 3>
B-NA, B- (N-1) A, ..., BA, B, B + A, ..., B + (N-1) A, B + NA Measure the tracking error amplitude at two points equidistant (C) from the focus bias.
For example, when the focus bias is B, the amplitude values of B−C and B + C are measured. When the focus bias is B + A, the amplitude values of B + A-C and B + A + C are measured.
The focus bias value when the difference in tracking error amplitude between the two points is the closest is set as the optimum focus bias.
[0078]
For example, in the case of such an optimum value detection method, the optimum value detection process takes more time than the above three-point measurement method, but the optimum focus bias can be accurately obtained even if the amplitude curve of the tracking error signal is not a quadratic curve. Value, and the spherical aberration correction value can be detected.
[0079]
5. Adjustment processing example [2]
Next, focus bias and spherical aberration adjustment processing will be described as an adjustment processing example [2] with reference to FIG.
In the above adjustment processing example [1], the optimum value of the spherical aberration correction value is detected and set, and then the optimum value of the focus bias value is detected and set. The adjustment process example [2] is executed in the reverse order.
[0080]
In the adjustment process, the focus servo is turned on and the tracking servo is turned off in step F201 in FIG.
In step F202, the adjustment value calculation unit 17 sets an initial value for measurement as a spherical aberration correction value in the spherical aberration correction value setting unit 20. The initial value for measurement may be stored in the nonvolatile memory 18 or the like as a predetermined value, for example.
[0081]
In a state in which the spherical aberration correction value is fixed at the initial value, in step F203, the amplitude value of the tracking error signal obtained from the amplitude measuring unit 19 is observed while changing the focus bias value in the focus bias setting unit 16, and the focus is adjusted. A process for searching for the optimum bias value is performed. That is, the above-described three-point measurement method, extended three-point measurement method, optimum value detection method, and the like are executed.
[0082]
When the optimum value as the focus bias value can be detected by the optimum value search process in step F203, the adjustment value calculation unit 17 sets the optimum value of the detected focus bias value in the focus bias setting unit 16 in step F204. .
Then, in a state where the focus bias value is fixed to the optimum value, in step F205, the amplitude value of the tracking error signal obtained from the amplitude measuring unit 19 is changed while changing the spherical aberration correction value in the spherical aberration correction value setting unit 20. Observe and perform processing for searching for an optimum value of the spherical aberration correction value. That is, a three-point measurement method, an extended three-point measurement method, an optimum value detection method, and the like are executed.
[0083]
When the optimum value as the spherical aberration correction value can be detected by the optimum value search processing in step F205, the adjustment value calculating unit 17 uses the detected spherical aberration correction value as the spherical aberration correction value setting unit in step F206. Set to 20.
With the above processing, the spherical aberration correction value and the focus bias value are adjusted to optimum values that maximize the amplitude of the tracking error signal, for example.
[0084]
6). Adjustment processing example [3]
An adjustment processing example [3] is shown in FIG.
In the process of FIG. 10, steps F301 and F303 to F306 are the same as steps F101 and F103 to F106 in the adjustment process example [1] of FIG.
[0085]
In the process of FIG. 10, the adjustment value calculation unit 17 stores the optimum focus bias value and the optimum spherical aberration correction value in the nonvolatile memory 18 as step F307.
That is, the non-volatile memory 18 stores the focus bias value set in the focus bias setting unit 16 and the spherical aberration correction value set in the spherical aberration correction value setting unit 20, which are detected by the optimum value search process similar to FIG.
[0086]
In step F302, the focus bias optimum value detected in the previous adjustment process and stored in the nonvolatile memory 18 is set as the focus bias value fixed to the initial value in order to search for the optimum value of the spherical aberration correction value. I am doing so.
By setting the previous focus bias optimum value as the initial value for measurement, the optimum value detection of the spherical aberration correction value can be executed more accurately.
[0087]
In addition, storing the optimum values of the focus bias and the spherical aberration correction value in the nonvolatile memory 18 enables the setting to the optimum values when necessary.
For example, even when adjustment using an RF signal is performed after adjustment in this example, the setting can be changed to an adjustment result based on the amplitude observation of the tracking error signal when necessary.
[0088]
Incidentally, in the procedure of the adjustment process example [2] in FIG. 9, the processes in steps F302 and F307 in FIG. 10 may be applied.
In that case, an initial value is initially set as the spherical aberration correction value. If the previous spherical aberration correction value optimum value stored in the nonvolatile memory 18 is used as the initial value of this spherical aberration correction value, Good.
[0089]
Further, in step F302 of FIG. 10, in addition to using the previous optimum value as the initial value, the past optimum value stored in the nonvolatile memory 18, such as using the average value of the past n optimum values, is used. There are various ways to do this.
[0090]
As a storage method in the non-volatile memory 18, for example, the non-volatile memory 18 may be used in the form of a ring buffer so that the optimum value history for the past predetermined number of times may be stored.
Alternatively, the optimum value stored in the nonvolatile memory 18 may be cleared, for example, when the disk 1 is replaced, and the optimum value according to the current disk may be stored. .
Furthermore, regardless of the exchange of the disk 1, it is stored as a sample of the required number of optimum values for a certain long period of time, and for example, the aging of devices such as a biaxial mechanism and a spherical aberration correction mechanism (change in response) It may be possible to set an initial measurement value reflecting the above.
[0091]
7. Adjustment processing example [4]
An adjustment processing example [4] will be described with reference to FIG.
In this adjustment process example [4], focus bias optimum value detection and spherical aberration correction value optimum value detection are alternately repeated.
[0092]
First, in step F401, the focus servo is turned on and the tracking servo is turned off. In step F402, the variable n is set to 1. The variable n is a variable that controls the number of times of detecting the optimum value.
[0093]
In step F403, the adjustment value calculation unit 17 sets an initial value for measurement as the focus bias value in the focus bias setting unit 16. The initial value for measurement is, for example, the optimum value detected by the previous adjustment process stored in the nonvolatile memory 18.
[0094]
In a state where the focus bias value is fixed at the initial value, in step F404, the amplitude value of the tracking error signal obtained from the amplitude measuring unit 19 is observed while changing the spherical aberration correction value in the spherical aberration correction value setting unit 20. Then, a process for searching for the optimum value of the spherical aberration correction value is performed. That is, the spherical aberration correction value optimum value is detected by a three-point measurement method, an extended three-point measurement method, an optimum value detection method, or the like.
[0095]
When the optimum value as the spherical aberration correction value can be detected by the optimum value search processing in step F404, the adjustment value calculating unit 17 uses the detected spherical aberration correction value as the spherical aberration correction value setting unit in step F405. Set to 20.
Then, in a state where the spherical aberration correction value is fixed to the optimum value, in step F406, the amplitude value of the tracking error signal obtained from the amplitude measuring unit 19 is observed while changing the focus bias value in the focus bias setting unit 16. Thus, a process for searching for the optimum value of the focus bias value is performed. That is, the focus bias optimum value is detected by a three-point measurement method, an extended three-point measurement method, an optimum value detection method, or the like.
[0096]
When the optimum value as the focus bias value is detected by the optimum value search process in step F406, the adjustment value calculating unit 17 sets the optimum value of the detected focus bias value in the focus bias setting unit 16 in step F407. .
In step F408, it is determined whether or not the variable n has reached a predetermined value K. The predetermined value K is a value determined as the number of repetitions.
[0097]
If n <K, the variable n is incremented in step F410 and the process returns to step F404.
At this time, the focus bias setting unit 16 sets the focus bias optimum value in step F407. Therefore, in step F404, the spherical aberration correction value setting unit 20 performs spherical aberration correction while fixing the focus bias optimum value. While changing the value, the amplitude value of the tracking error signal obtained from the amplitude measuring unit 19 is observed to search for the optimum value of the spherical aberration correction value.
[0098]
When the optimum value as the spherical aberration correction value is detected in step F404, the detected optimum value of the spherical aberration correction value is set in the spherical aberration correction value setting unit 20 in step F405. Then, in a state where the spherical aberration correction value is fixed to the optimum value, in step F406, processing for searching for the optimum value of the focus bias value is performed while changing the focus bias value in the focus bias setting unit 16.
In step F407, the optimum value of the detected focus bias value is set in the focus bias setting unit 16.
[0099]
Such a process is repeated until it is determined in step F408 that the variable n has reached the predetermined value K.
When the K repetitive processes are completed, the process proceeds to step F409, where the focus bias optimum value and the spherical aberration correction value optimum value set at that time are stored in the nonvolatile memory 18 and the process is terminated.
[0100]
Through the above processing, the spherical aberration correction value and the focus bias value are adjusted to optimum values.
In particular, the focus bias and the spherical aberration correction value are obtained by repeatedly performing the process of searching for the optimum value while the other optimum value detected immediately before is fixed. It will be driven and converge, and adjustment with higher accuracy becomes possible.
[0101]
In the example of FIG. 11, the search is performed in the order of the search for the optimal value of the spherical aberration correction value → the search for the optimal value of the focus bias → the search for the optimal value of the spherical aberration correction value →. The search may be performed in the order of value search → optimum value search for spherical aberration correction value → optimum value search for focus bias →.
[0102]
8). Adjustment processing example [5]
The adjustment processing example [5] will be described with reference to FIG.
In this adjustment processing example [5], inappropriate values are excluded when detecting the optimum value of the focus bias and the optimum value of the spherical aberration correction value.
[0103]
Steps F501, F502, F503, F505, F507, F509, and F511 in FIG. 12 are the same as steps F301 to F307 in FIG.
In this case, when the search process for the spherical aberration correction value optimum value is executed in step F503, it is determined in step F504 whether or not the detected optimum value is a value within a predetermined range. The predetermined range here is a range in which it can be determined that the spherical aberration correction value is not an abnormal value. For example, it is set in advance as an appropriate range.
If the detected spherical aberration correction value optimum value is within the predetermined range, the detected optimum value is set in the spherical aberration correction value setting unit 20 in step F505.
However, if the detected spherical aberration correction value optimum value is not within the predetermined range, the process proceeds to step F506, where the detected optimum value is discarded, and the optimum value is determined from the values stored in the nonvolatile memory 18. The spherical aberration correction value setting unit 20 is set. For example, the optimum spherical aberration correction value at the previous adjustment process is applied.
[0104]
Further, when the focus bias optimum value search process is executed in step F507, it is determined in step F508 whether or not the detected optimum value is a value within a predetermined range. This predetermined range is a range in which it can be determined that the focus bias value is not an abnormal value.
If the detected focus bias optimum value is within the predetermined range, the detected optimum value is set in the focus bias setting unit 16 in step F509.
However, if the detected focus bias optimum value is not within the predetermined range, the process proceeds to step F510, the detected optimum value is discarded, and the optimum value is obtained from the value stored in the nonvolatile memory 18, The focus bias setting unit 16 is set. For example, the focus bias optimum value in the previous adjustment process is applied.
[0105]
By such a process, if an abnormal value is detected in the optimum value search process, the abnormal value is prevented from being used as the optimum value, so that the error can be prevented from expanding.
At this time, if the past optimum value stored in the nonvolatile memory 18 or the average value of the past optimum value is used, the state of an appropriate value can be maintained to some extent.
[0106]
Note that when the optimum value determined to be an abnormal value is discarded, the optimum value to be used instead of the optimum value obtained by past adjustment processing such as the previous time may be a fixed value set in advance.
Further, combining the process of discarding such an abnormal value as the optimum value and the process of performing the repeated optimum value search shown in FIG. 11 is also suitable for improving the adjustment process accuracy.
[0107]
9. Adjustment timing
There are various timings for executing the adjustment processing described in the various examples as the adjustment processing examples [1] to [5].
First, it is appropriate to execute it when the disc is loaded. When a disc is loaded, processing such as reading of the disc management information is usually performed. For this reason, in order to reproduce the RF signal, it is necessary to adjust the focus bias and the spherical aberration. Therefore, it is appropriate to perform the adjustment process first when a disk is loaded.
[0108]
In addition, it may be executed during reproduction, before and after seek, or after a predetermined time has elapsed, or in accordance with the trace position (inner and outer circumference) on the disc.
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.
[0109]
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 process is executed regularly or irregularly, which is appropriate for stabilizing the operation of the apparatus. It is also conceivable to perform servo gain adjustment processing triggered by temperature change detection, reproduction data error rate / jitter deterioration, or the like.
[0110]
10. Modified example
The present invention is not limited to the above embodiment, and various modifications are conceivable.
In particular, other than the adjustment processing examples [1] to [5], various adjustment processing procedures are conceivable.
[0111]
Various optimum value detection methods described in the three-point measurement method are also conceivable.
For example, according to the examples of FIGS. 6 to 8, the optimum value of the spherical aberration correction value and the tracking error amplitude are stored in the focus bias BA, and then the optimum value of the spherical aberration correction value and the tracking error are stored in the focus bias B. The amplitude is memorized, and the most desirable condition (the tracking error amplitude is maximized, the spherical aberration correction amount is small, the focus is adjusted, etc.) by looking at the optimum spherical aberration correction value corresponding to each focus bias. There is a method of optimizing the focus bias value and the spherical aberration correction value (for example, the bias amount is small). In other words, a two-dimensional map is drawn with the focus bias and the spherical aberration correction value to find the optimum point.
Of course, conversely, a method of finding the optimum value of the two-dimensional map using the optimum value of the focus bias and the tracking error amplitude while moving the spherical aberration correction value is also conceivable.
[0112]
When such a method is used, since the optimum values of the focus bias and the spherical aberration correction value are simultaneously determined, the adjustment processing procedure is different from the adjustment processing examples [1] to [5]. Become.
That is, after the focus servo is turned on and the tracking servo is turned off, the process for searching the optimum values of the focus bias and the spherical aberration correction value from the two-dimensional map is performed by the above method, and the detected optimum values are detected by the focus bias setting unit 16 and the spherical aberration. This is a processing procedure of setting in the correction value setting unit 20.
[0113]
【The invention's effect】
As can be understood from the above description, according to the present invention, the optimum focus bias value and the optimum spherical aberration correction value can be found using the amplitude of the tracking error signal. Without adjusting the focus bias, it is possible to provide an indispensable technique in a disk drive device in which all other adjustments such as laser power, detailed spherical aberration correction using an RF signal, and focus bias correction cannot be guaranteed. That is, by adjusting the optimal focus bias value and the optimal spherical aberration correction value using the amplitude of the tracking error signal, the reliability of the subsequent recording / reproducing operation and adjusting operation is improved, and consequently the recording / reproducing performance is improved. Can be made.
In addition, since it is possible to know the spherical aberration correction correction value and the focus bias value at which the tracking error is optimal, even when the adjustment result using the RF signal is used at the time of data recording / reproducing, for example, the stability of the servo such as seek is improved In a required scene, a method of operating using the focus bias and the spherical aberration correction value obtained by the present invention can be adopted.
[0114]
As a specific procedure, the focus bias is set to a predetermined value, the tracking error signal is observed while changing the spherical aberration correction value, the optimum spherical aberration correction value is detected and set, and then the focus bias value is set. By observing the tracking error signal while changing and detecting the optimum focus bias value, it is possible to easily detect the optimum values of the focus bias and the spherical aberration correction value.
Or, conversely, set the spherical aberration correction value to a predetermined value, observe the tracking error signal while changing the focus bias value, detect and set the optimal focus bias value, and then change the spherical aberration correction value The same applies to the operation of observing the tracking error signal while detecting the optimum spherical aberration correction value.
[0115]
In addition, by storing the detected optimum value of the focus bias and the optimum value of the spherical aberration correction value in the storage unit, the detection operation can be performed using the previous optimum value, the past optimum value average value, or the like. This enables efficient and highly accurate detection / setting operation.
If the detected optimum value is not within the predetermined range, it is appropriate to maintain the operation reliability by setting a detection error, and in that case, by applying the past optimum value stored, it is possible to Can also respond appropriately.
[0116]
In addition, the focus bias is set, the tracking error signal is observed while changing the spherical aberration correction value, and an appropriate spherical aberration correction value is detected based on the amplitude of the observed tracking error signal, and the spherical aberration correction value And observing the tracking error signal while changing the focus bias value, and detecting the appropriate focus bias value based on the amplitude of the observed tracking error signal. The optimum values of the focus bias value and the spherical aberration correction value can be pursued, and adjustment with higher accuracy becomes possible.
[0117]
As specific detection processing of each optimum value, the focus bias value or the spherical aberration correction value is changed from a predetermined value to three at regular intervals, and the amplitude of the tracking error signal in each case is measured, By detecting the optimal value of the focus bias or the optimal value of the spherical aberration correction value by the arithmetic processing that performs quadratic curve approximation using the three measurement results, the detection can be performed easily and quickly. In other words, the adjustment time is quicker than the adjustment of the focus bias and the spherical aberration correction value, and the time until the data recording / reproduction preparation is completed can be shortened.
[0118]
In addition, the focus bias value or the spherical aberration correction value is changed from a predetermined value to three or more in equal intervals, the amplitude of the tracking error signal in each case is measured, and selected based on each measurement result. When the optimum value of the focus bias or the optimum value of the spherical aberration correction is detected by a calculation process that performs quadratic curve approximation using the three measurement results, a large amount of spherical aberration occurs (disc cover thickness). Appropriate adjustment can be made corresponding to the case where the error is large.
[0119]
In addition, the amplitude of the tracking error signal is measured while changing the focus bias value or the spherical aberration correction value from the predetermined value, and the value at which the amplitude of the tracking error signal is optimal is set to the optimum value of the focus bias or Appropriate adjustment is also possible by the method of detecting the spherical aberration correction value as the optimum value. This is particularly effective when it is assumed that the method using quadratic curve approximation is not suitable.
[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 flowchart of an adjustment processing example [1] according to the embodiment.
FIG. 6 is an explanatory diagram of a detection operation by a three-point measurement method according to the embodiment.
FIG. 7 is an explanatory diagram of a detection operation by the extended three-point measurement method according to the embodiment.
FIG. 8 is an explanatory diagram of a detection operation by an optimum value detection method according to the embodiment.
FIG. 9 is a flowchart of an adjustment process example [2] according to the embodiment;
FIG. 10 is a flowchart of an adjustment process example [3] according to the embodiment;
FIG. 11 is a flowchart of an adjustment process example [4] according to the embodiment;
FIG. 12 is a flowchart of an adjustment process example [5] according to the embodiment;
[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 adjustment value calculation , 18 Nonvolatile memory, 19 Amplitude measurement unit, 20 Spherical aberration correction value setting unit, 22 Tracking servo calculation unit, 24 Tracking driver, 26 Spherical aberration correction driver, 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 120 AV system Mu

Claims (2)

Head writing means for performing laser irradiation and reflected light detection on a disk recording medium for data writing or reading, and having a laser beam focus servo mechanism, tracking servo mechanism, and spherical aberration correction mechanism;
An error signal generating means for generating a focus error signal and a tracking error signal from the reflected light obtained by the head means, and
A focus servo means for generating a focus servo drive signal based on the focus error signal and driving the focus servo mechanism to execute focus servo;
Tracking servo means for generating a tracking servo drive signal based on the tracking error signal, driving the tracking servo mechanism and executing tracking servo; and
Spherical aberration correction means for generating a spherical aberration correction drive signal based on the spherical aberration correction value and driving the spherical aberration correction mechanism to perform spherical aberration correction;
Focus bias means for adding a focus bias to a focus loop including the focus servo means;
While observing the tracking error signal, the optimum value of the focus bias and the optimum value of the spherical aberration correction value are detected and added by the focus bias means, and the spherical aberration correction in the spherical aberration correction means Adjusting means for setting the values to optimum values,
Equipped with a,
The adjusting means is
The focus bias value or spherical aberration correction value is changed from three to three at regular intervals, the amplitude of the tracking error signal in each case is measured, and quadratic curve approximation is performed using the three measurement results. A disk drive device that detects the optimum value of the focus bias or the optimum value of the spherical aberration correction value by performing arithmetic processing . Focus bias and spherical surface in a disk drive apparatus that performs laser irradiation and reflected light detection on a disk recording medium for writing or reading data, and has a focus servo mechanism, a tracking servo mechanism, and a spherical aberration correction mechanism for laser light As an aberration adjustment method,
While observing the tracking error signal generated from the reflected light with the focus servo turned on and the tracking servo turned off, the optimum focus bias value and spherical aberration correction value to be added to the focus servo loop Detecting step;
A step of setting a focus bias value to be added to the focus servo loop and a spherical aberration correction value for driving the spherical aberration correction mechanism, respectively, to detected optimum values ;
In the step of detecting the optimum value, the focus bias value or the spherical aberration correction value is changed from the predetermined value to three or more at regular intervals, and the amplitude of the tracking error signal in each case is measured, Focus bias and spherical aberration adjustment method for detecting the optimum value of the focus bias or the optimum value of the spherical aberration correction value by an arithmetic process that performs quadratic curve approximation using three measurement results selected based on the measurement result .

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