JP4036061B2 - Disk drive device and servo gain adjustment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disk drive device and a servo gain adjustment method for a disk recording medium such as an optical disk.
[0002]
[Prior art]
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]
[Problems to be solved by the invention]
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 on the disk recording surface, or a track on the disk (tracks by pit rows or grooves (grooves)) on the disk. Tracking servo operation is performed to control to trace).
In these focus servo and tracking servo, it is necessary to stabilize the gain of the servo loop in order to stabilize the operation.
[0004]
As a conventionally known method for adjusting the servo loop gain, a response waveform (amplitude may be used or a phase may be used) as a result of adding an adjustment source signal having a certain frequency to the servo loop. Some servo loop characteristics are calculated and the servo loop gain is adjusted to a constant value.
However, for example, when the disk noise is high due to the molding condition of the groove on the disk and there is noise over all frequencies, the observed signal of the response waveform contains many noise components with the same frequency as the adjustment source. The noise component cannot be completely removed even by filtering such as a bandpass filter, and the response waveform cannot be observed appropriately. As a result, the servo gain calculation using the adjustment source signal and the response waveform also includes a lot of errors, and it is impossible to adjust the accuracy sufficient for practical use.
[0005]
Further, if an adjustment source signal having a large amplitude that can sufficiently ignore the noise component is added, a certain degree of calculation accuracy can be secured, but in that case, servo stability during servo gain adjustment cannot be secured. . This is because the addition of the adjustment source signal means that a disturbance is added to the servo loop, that is, the disturbance component increases as the adjustment source signal becomes larger in amplitude.
If the servo stability cannot be ensured, for example, it is not appropriate to adjust the servo gain during reproduction or seek.
[0006]
[Means for Solving the Problems]
In view of these circumstances, it is an object of the present invention to make it possible to adjust the loop gains of focus servo and tracking servo with high accuracy and to perform loop gain adjustment without losing servo stability.
[0007]
  For this purpose, the disk drive apparatus of the present invention provides a head error means for performing laser irradiation and detection of reflected light on a disk recording medium and a servo error signal from the reflected light obtained by the head means for data writing or reading. Servo error signal generating means to generate, servo signal generating means for performing a predetermined process including gain processing on the servo error signal, generating and outputting a servo signal, and output from the servo signal generating means Based on the servo signal, the servo drive means for executing the servo operation of the head means, and the adjustment source signal of the specific frequency,Two waysThe adjustment source signal generating means that can generate signals having different amplitudes and add them to the servo error signal, and observe the amplitude of the servo loop response waveform generated by adding the adjustment source signal to the servo error signal Of the observation source for the adjustment source signalTwo waysAnd the above-mentioned adjusted source signalTwo waysThe servo loop gain adjustment value is calculated by performing an operation using the servo loop response waveform corresponding to the amplitude when each amplitude is added to the servo error signal and the servo loop characteristic value, and the servo signal Servo gain adjusting means for adjusting the gain value in the gain processing of the generating means;Control means for executing addition of two different amplitudes of the adjustment source signals to the servo error signal and observation of the servo loop response waveform at the same location or in the vicinity of the disc recording medium;WithThe servo gain adjusting means performs an operation of subtracting each servo loop response waveform observed corresponding to each amplitude when the two amplitudes of the adjustment source signal are added to the servo error signal. I do.
  The servo gain adjusting means includes a storage means for storing the adjustment value calculated by the servo gain adjusting means, and the servo gain adjusting means is an average value of the calculated adjustment value and the past adjustment value stored in the storage means. And the gain value in the gain processing of the servo signal generating means is adjusted by the average value.
  In addition, when a disc recording medium is loaded, a control unit is provided for adjusting the gain value in the gain processing by the adjustment source signal generation unit, the observation unit, and the servo gain adjustment unit.
  In addition, after the disk recording medium is loaded, the gain value in the gain processing is adjusted by the adjustment source signal generation means, the observation means, and the servo gain adjustment means at a predetermined timing during the operation execution period for the disk recording medium. Control means are provided.
[0008]
  In the servo gain adjustment method of the present invention, as an adjustment source signal of a specific frequency,Two waysAre generated and added to the servo error signal, and the amplitude of the servo loop response waveform generated by adding the adjustment source signal of each amplitude to the servo error signal is observed, and the adjustment source SignalTwo waysAnd the above-mentioned adjusted source signalTwo waysThe servo loop gain adjustment value is calculated by performing an operation using the servo loop response waveform corresponding to the amplitude when each amplitude is added to the servo error signal and the servo loop characteristic value. Adjust the servo gain using the adjusted valueAt the same time, addition of the two different amplitude adjustment source signals to the servo error signal and observation of the servo loop response waveform are performed at the same location on the disk recording medium or at a nearby location.AndIn calculating the adjustment value, the servo loop response waveforms observed corresponding to the respective amplitudes when the two amplitudes of the adjustment source signal are added to the servo error signal, Make sure that the subtraction operation is included.
  In addition, the calculated adjustment value is stored, and at the time of servo gain adjustment, an average value of the calculated adjustment value and the stored past adjustment value is calculated, and the servo gain is calculated based on the average value. adjust.
  When a disk recording medium is loaded, the adjustment of the servo gain is performed by generating the adjustment source signal and adding it to the servo error signal, observing the servo loop response waveform, and calculating the adjustment value. .
  In addition, after the disk recording medium is loaded, the adjustment source signal is generated and added to the servo error signal, the servo loop response waveform is observed, and the adjustment value is adjusted at a predetermined timing in the operation execution period for the disk recording medium. Execute the calculation and adjust the servo gain.
[0009]
  According to the present invention having the above configuration, as an adjustment source signal used for one servo gain adjustment,Two waysIs added to the servo loop. Then, the response waveform amplitudes corresponding to the respective amplitude adjustment source signals are subtracted from each other and used for the calculation of the servo gain adjustment value. In this case, a noise component having the same frequency as that of the adjustment source signal can be canceled. Accordingly, it is not necessary to input a large-amplitude signal that can ignore the noise component as the adjustment source signal.
[0010]
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 a servo gain adjusting method thereof will be described. The description will be given in the following order.
1. Configuration of disk drive device
2. Servo system configuration
3. Servo gain adjustment processing example [1]
4). Servo gain adjustment processing example [2]
5. Position and timing for servo gain adjustment
6). Modified example
[0011]
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.
[0012]
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.
[0013]
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.
[0014]
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.
[0015]
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.
[0016]
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.
[0017]
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.
[0018]
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.
[0019]
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.
[0020]
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.
[0021]
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.
[0022]
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.
[0023]
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.
[0024]
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.
[0025]
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.
[0026]
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.
[0027]
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.
[0028]
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.
[0029]
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.
[0030]
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.
[0031]
2. 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 is shown in FIG. 2.
[0032]
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.
[0033]
The focus servo calculation unit 12 performs a predetermined calculation on the focus error signal FE input as digital data to generate and output a focus servo signal FS. 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.
[0034]
The tracking servo calculation unit 22 performs a predetermined calculation on the tracking error signal TE input as digital data to generate and output a tracking servo signal TS. 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.
[0035]
For example, the operations of the focus servo calculation unit 12 and the tracking servo calculation unit 22 formed in the DSP 10 are controlled by the system controller 60. In particular, as described later, operation control for servo gain adjustment is performed.
The memory unit 30 is, for example, a non-volatile memory, and stores a servo gain adjustment value. This will be described in the servo gain adjustment processing example [2] (FIG. 6).
[0036]
The configuration of the tracking servo calculation unit 22 shown in FIG. 2 is shown in FIG.
The tracking servo calculation unit 22 is provided with a servo processing unit 43 and a variable gain unit 46 as functional parts forming a normal tracking servo loop.
The servo processing unit 43 performs filter processing for phase compensation or the like on the tracking error signal TE. The variable gain unit 46 performs loop gain processing.
The tracking error signal TE input to the tracking servo calculation unit 22 is converted into a tracking servo signal TS through the processing of the servo processing unit 43 and the variable gain unit 46. As shown in FIG. 2, the D / A converter 23 is supplied to the tracking driver 24.
[0037]
The tracking servo calculation unit 22 is provided with an adjustment source signal generation unit 42, an adder 41, a filter unit 44, and a response waveform measurement / gain calculation unit 45 for servo gain adjustment.
The adjustment source signal generation unit 42 digitally generates an adjustment source signal as a sine wave having a specific frequency. In this case, signals having various amplitudes can be output as the amplitude of the adjustment source signal.
For example, like the SIN (A) and SIN (B) shown in FIG. 4, the adjustment source signals having the same frequency and different amplitudes are output.
At this time, the frequency of the adjustment source signals SIN (A) and SIN (B) is selected such that the phase of the servo open loop hardly changes due to various perturbations (such as variations in circuit element characteristics).
If the frequency of the adjustment source signals SIN (A) and SIN (B) is too low, it is difficult to calculate the loop response waveform for the adjustment source signals SIN (A) and SIN (B). This is because the amplitude measurement time is extended, and the response waveform becomes small because the loop gain is high.
Therefore, in this example, the frequency of the adjustment source signal is selected to be about 1 KHz to 2 KHz.
[0038]
The adder 41 adds the adjustment source signals SIN (A) and SIN (B) to the tracking error signal TE digitized by the A / D converter 21 of FIG.
The tracking error signal TE after adding the adjustment source signal SIN (A) or SIN (B) has the same frequency component as that of the adjustment source signal SIN (A) or SIN (B), and a sign as a response waveform of the servo loop. Wave components appear.
The filter unit 44 extracts only the same frequency component as the adjustment source signals SIN (A) and SIN (B) using a bandpass filter, a low pass filter, a high pass filter, etc., and corresponds to the adjustment source signal SIN (A) Output as a loop response waveform RES (A) and a loop response waveform RES (B) corresponding to the adjustment source signal SIN (B).
[0039]
The response waveform measurement / gain calculation unit 45 measures the amplitudes of the loop response waveforms RES (A) and RES (B), and adjusts the amplitudes of the adjustment source signals SIN (A) and SIN (B) and the loop response waveform RES. Calculation using the amplitudes of (A) and RES (B) and the servo loop characteristic value is performed to calculate the adjustment value of the servo loop gain, and the gain value of the variable gain unit 46 is adjusted.
[0040]
Although FIG. 3 shows a configuration example as the tracking servo calculation unit 22, the configuration of the focus servo calculation unit 12 is also the same. That is, phase compensation and servo gain processing are performed on the focus error signal FE at portions corresponding to the servo processing unit 43 and the variable gain unit 46, and an adjustment source signal generation unit 42 and an adder 41 are used to adjust the servo loop gain. , A part corresponding to the filter unit 44 and the response waveform measurement / gain calculation unit 45 is provided.
Hereinafter, the servo gain adjustment operation will be described with reference to the tracking servo calculation unit 22, and the operation is also executed in the same manner in the focus servo calculation unit 12.
[0041]
3. Servo gain adjustment processing example [1]
A servo gain adjustment process by the tracking servo calculation unit 22 configured as shown in FIG. 3 will be described.
The relational expression among the adjustment source signal SIN (A) amplitude output from the adjustment source signal generation unit 42, the servo open loop gain G, the servo open loop phase Θ, and the response waveform RES (A) amplitude is as follows: expressed.
(RES (A) amplitude) = √ (1 / ((G + 1) × (G + 1) + 2 × G × cosΘ)) × (SIN (A) amplitude) (Equation 1)
[0042]
The servo open loop gain determined by design is G0, and the servo open loop phase is Θ0.
RES (A1) is the loop response waveform obtained as a result of adding the adjustment source signal SIN (A) to the servo loop at a certain point in time, the servo open loop gain at that time is G1, and the servo open loop phase hardly changes. given that,
(RES (A1) amplitude) = √ (1 / ((G1 + 1) x (G1 + 1) + 2 x G1 x cosΘ0))
× (SIN (A) amplitude) (Equation 2)
The following equation holds.
[0043]
Immediately after executing the addition of the adjustment source signal SIN (A) and the acquisition of the loop response waveform amplitude RES (A1), the adjustment source signal SIN (A) and When the adjusted source signal SIN (B) with the same frequency and different amplitude is added to the loop, it is close to the time and place, so the servo open loop gain when adding the adjusted source signal SIN (B) is G1 The value is almost as close as possible, and can be calculated by approximating G1. Therefore, if the loop response waveform for the adjustment source signal SIN (B) is RES (B1),
(RES (B1) amplitude) = √ (1 / ((G1 + 1) x (G1 + 1) + 2 x G1 x cosΘ0))
× (SIN (B) amplitude) (Equation 3)
And can.
[0044]
Here, (Equation 2) and (Equation 3) are subtracted from both the left side and the right side. That is
(RES (A1) amplitude-RES (B1) amplitude)
= √ (1 / ((G1 + 1) × (G1 + 1) + 2 × G1 × cosΘ0))
× (SIN (A) amplitude-SIN (B) amplitude) (Equation 4)
The following formula is obtained.
[0045]
Solving this (Equation 4) for G1 and finding the ratio to G0,
G0 / G1 = G0 / (-cosΘ0 + √ (cosΘ0 × cosΘ0-1
+ (SIN (A) amplitude -SIN (B) amplitude) x (SIN (A) amplitude -SIN (B) amplitude)
/ ((RES (A1) amplitude-RES (B1) amplitude) x (RES (A1) amplitude-RES (B1) amplitude)))
... (Formula 5)
It becomes.
By this (Equation 5), the ratio between the design gain and the current open loop gain can be calculated. If the current setting of the variable gain unit 46 is the gain α, the open loop gain can be adjusted to the design gain G0 by setting α × G0 / G1 to the variable gain unit.
[0046]
In order to perform servo gain adjustment by such processing, based on the control of the system controller 60, the tracking servo calculation unit 22 executes servo gain adjustment processing in the procedure of FIG.
First, in step F101, the adjustment source signal generator 42 outputs the adjustment source signal SIN (A). Then, as described above, the adder 41 adds the adjustment source signal SIN (A) to the tracking error signal TE, and the tracking error signal TE has the same frequency component as the adjustment source signal SIN (A), and the response of the servo loop. A sine wave component appears as a waveform.
In step F102, the amplitude of the loop response waveform RES (A) is measured. That is, the response waveform measurement / gain calculation unit 45 measures the amplitude of the loop response waveform RES (A) obtained by extracting only the same frequency component as the adjustment source signal SIN (A) by the filter unit 44.
[0047]
Subsequently, in step F103, the adjustment source signal generator 42 outputs the adjustment source signal SIN (B). Then, the adder 41 adds the adjustment source signal SIN (B) to the tracking error signal TE, and the tracking error signal TE has the same frequency component as that of the adjustment source signal SIN (B) and a sign as a response waveform of the servo loop. Wave components appear.
In step F104, the amplitude of the loop response waveform RES (B) is measured. That is, the response waveform measurement / gain calculation unit 45 measures the amplitude of the loop response waveform RES (B) obtained by extracting only the same frequency component as the adjustment source signal SIN (B) by the filter unit 44.
[0048]
In step F105, the response waveform measurement / gain calculation unit 45 calculates the gain ratio G0 / G1. That is, using the amplitudes of the adjustment source signals SIN (A) and SIN (B), the amplitudes of the loop response waveforms RES (A) and RES (B), and the servo loop characteristic value, the calculation of (Expression 5) above is performed. To obtain the ratio between the servo open loop gain G0 determined by design and the gain G1 at the time of addition.
In step F106, the current setting gain α of the variable gain section 46 is set to α × G0 / G1.
This completes the process of adjusting the open loop gain to the design gain G0.
[0049]
In such servo gain adjustment processing, the amplitudes of the response waveforms RES (A) and RES (B) corresponding to the adjustment source signals SIN (A) and SIN (B) are subtracted from each other and used to calculate the servo gain adjustment value. To do. For this reason, noise components having the same frequency as the adjustment source signal (such as noise due to the disk) can be canceled and only the desired servo loop response component can be extracted and calculated, so that servo gain adjustment with less error is realized.
This also eliminates the need to input a large-amplitude signal with negligible noise components as the adjustment source signals SIN (A) and SIN (B), so servo gain adjustment is performed without compromising servo stability. it can.
[0050]
4). Servo gain adjustment processing example [2]
A servo gain adjustment process example [2] is shown in FIG.
In the processing example of FIG. 5 described above, α × G0 / G1 obtained from the gain ratio G0 / G1 obtained by the calculation of (Equation 5) and the current setting gain α of the variable gain unit 46 is set.
On the other hand, the processing example of FIG. 6 stores the gain value calculated at the time of gain adjustment processing using the memory unit 30 and adjusts the gain to an averaged value using the stored past gain values. is there.
[0051]
Steps F201 to F205 in FIG. 6 are the same as steps F101 to F105 in FIG.
In step F206, the response waveform / gain calculation unit 45 calculates a new gain α that is α × G0 / G1 for the current setting gain α of the variable gain unit 46.
In step F207, the response waveform / gain calculation unit 45 reads the gain value α stored in the past predetermined number of servo gain adjustment processes stored in the memory unit 30, respectively, and calculates the gain α calculated in step F206 this time and the past An average value αAV of each gain α for a predetermined number of times is calculated.
In step F208, the response waveform / gain calculation unit 45 controls the set gain of the variable gain unit 46 to be the average value αAV.
In step F209, the gain α calculated in step F206 this time is stored in the memory 30 as the latest gain history.
[0052]
That is, in the processing example of FIG. 6, the set gain calculated for each servo gain adjustment process is stored in the memory unit 30.
For the actual gain setting of the variable gain unit 46, the gain value stored in the past servo gain adjustment process and the gain value calculated this time are averaged, and the gain is set to the average value.
By performing gain control using the average value in this way, the response to a temporary and steep gain fluctuation can be dulled, and stable loop gain adjustment can be performed.
[0053]
As a storage method in the memory unit 30, for example, the memory unit 30 may be used in the form of a ring buffer so that a past predetermined number of gain histories may be stored, and may not necessarily be used for averaging. The number of samples need not be constant. Further, the gain value stored in the memory unit 30 may be cleared when the disk 1 is replaced, for example.
Alternatively, regardless of the exchange of the disk 1, if it is stored as a required number of gain samples for a long period of time and used for calculating the average value, for example, the aging of a device such as a biaxial mechanism (servo response) (Gain change) can be adjusted.
[0054]
5. Position and timing for servo gain adjustment
The servo loop gain is automatically adjusted to the design value by the servo gain adjustment processing example [1] or [2]. In each processing example, each of the adjustment source signals SIN (A) and SIN (B) having two amplitudes is adjusted. Using the amplitude and the amplitude of the loop response waveforms RES (A) and RES (B) and subtracting them as shown in (Equation 4) above, the noise component caused by the disc is canceled and highly accurate adjustment is performed. It is realized.
For this reason, it is optimal that the position on the disk when the adjustment source signal SIN (A) is output and the position on the disk when the adjustment source signal SIN (B) is output be the same or in the vicinity. It is.
That is, at the same position, the noise components due to the disk, such as the degree of groove formation and uneven reflectance, are the same, and therefore the noise components are most appropriately canceled by subtraction of (Equation 4). In addition, since the non-uniformity of the reflectance on the disk board surface is similar at the near position, the noise components are similar, and the noise components are appropriately canceled by subtraction of (Equation 4).
[0055]
To add the adjustment source signal SIN (A) and observe the response waveform RES (A) and to add the adjustment source signal SIN (B) and observe the response waveform RES (B) at the same position on the disk 1 The trace position may be accessed between steps F102 and F103 in FIG. That is, if the generation of the adjustment source signal SIN (A) in step F101 is started at the trace timing of the address ad1 on the disk, the generation of the adjustment source signal SIN (B) in step F103 is also the address ad1 on the disk. If it is started in the state of accessing, the addition and observation at the same position becomes possible.
In addition, as shown in FIG. 4, the processing of steps F101 and F102 and the processing of steps F103 and F104 are performed continuously without taking time in the processing of FIG. As a result, the servo gain can be adjusted with high accuracy.
[0056]
Various timings for executing the servo gain adjustment processing example [1] or [2] can be considered.
First, it is appropriate to execute it when the disc is loaded. When a disc is loaded, processing such as reading of disc management information is usually performed, and servo gain adjustment processing is executed at that time. By executing the servo gain adjustment process at the time of loading the disk, an appropriate servo gain adjustment corresponding to each disk is performed.
[0057]
Further, it may be executed during reproduction, before and after seeking, or after a predetermined time has elapsed.
The servo gain adjustment processing in this example does not require input of an adjustment source signal as a large-amplitude signal that can ignore the noise component. Therefore, servo gain adjustment can be performed without losing servo stability. There is no problem even if the servo gain adjustment processing is performed during the operation period such as sine and seek.
Therefore, for example, during reproduction, the data read from the disk 1 can be performed at a timing with a margin for buffering.
In addition, the timing immediately before the seek or immediately after the seek is also suitable as the execution timing of the servo gain adjustment process.
[0058]
The servo gain is preferably adjusted according to the temperature state of the device (change in gain due to the temperature characteristics of the device and actuator), aging, and the trace position (radius position) on the disk. Therefore, even during the operation period with respect to the disk 1, the servo gain adjustment processing 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.
[0059]
6). Modified example
The present invention is not limited to the above embodiment, and various modifications are conceivable.
For example, the adjustment source signal generation unit 42 may be configured by an analog circuit. In that case, the adjustment source signal generation unit 42 may be placed before the A / D converters 11 and 21 or after the D / A converters 13 and 23. .
[0060]
When the variable gain unit 46 is configured in a digital circuit, it may be inserted anywhere in the digital operation unit (DSP 10). For example, it may be immediately after the A / D converters 11 and 21, or may be in the middle of the loop shaping filter (servo processing unit 43).
The variable gain unit 46 may be configured with an analog circuit. In that case, it may be placed before the A / D converters 11 and 21, or after the D / A converters 13 and 23.
[0061]
In the above example, the amplitude of the generated adjustment source signal is SIN (A) and SIA (B), but may be three or more. For example, if response waveforms can be measured with four different amplitudes, a method may be considered in which the gain ratio G0 / G1 is obtained from the amplitude difference between the response waveforms and the average value is used.
[0062]
Further, regarding the acquisition of the amplitudes of the loop response waveforms RES (A) and RES (B), it is conceivable that the abnormal values are discarded. For example, the amplitude of the loop response waveform as a value far from the design value is not used as any observation error, thereby improving accuracy.
In addition, as each output period of the adjustment source signal SIN (A), SIA (B), given a certain amount of time, by performing a process such as observing a plurality of samples of the response waveform amplitude within that time and taking an average, Further, a method for increasing the calculation accuracy can be considered.
[0063]
【The invention's effect】
As can be understood from the above description, according to the present invention, two or more amplitude signals are added to the servo loop as adjustment source signals used for one servo gain adjustment, and each amplitude adjustment source signal is supported. The response waveform amplitudes to be subtracted from each other are used to calculate the servo gain adjustment value. For this reason, noise components with the same frequency as the adjustment source signal (such as noise caused by the disk) can be canceled, and only the desired servo loop response component can be extracted and calculated. There is.
As a result, it is not necessary to input a large amplitude signal that can ignore the noise component as the adjustment source signal. Therefore, there is an effect that the servo gain adjustment can be executed without losing the servo stability.
[0064]
Further, if the addition of two or more kinds of adjustment source signals having different amplitudes and the measurement of the loop response waveform are performed at exactly the same location on the disc, the noise components caused by the disc are the same. By subtracting the response waveform amplitudes corresponding to each other, a very suitable noise cancellation becomes possible, and the calculation accuracy can be further improved. Even in the vicinity of the disk, the noise components due to the disk are similar, so the noise canceling effect is great.
[0065]
In addition, if the average value of the calculated adjustment value and the stored past adjustment value is used during the servo gain adjustment, the response to the temporary and steep gain fluctuation is dulled and stabilized. Loop gain adjustment can be performed. This is also suitable for maintaining the servo stability.
[0066]
Servo gain adjustment is performed when an operation is performed on the disk recording medium when the disk recording medium is loaded or after the disk recording medium is loaded.
By performing servo gain adjustment when a disk recording medium is loaded, an appropriate servo gain can be set for each disk.
Further, since the servo stability is not impaired as described above, there is no problem in performing the operation on the disk recording medium, for example, during reproduction or before and after seek.
Servo gain adjustment is performed periodically, for example, before and after seeking during disk recording / playback, so that the servo gain changes due to the temperature rise of the disk drive device (gain changes due to the temperature characteristics of the device and actuator). Accordingly, the servo system can always be adjusted to the design gain.
Further, by performing servo gain adjustment periodically, for example, during the operation execution period, the servo system can always be kept at the design gain even when the servo gain changes due to the disk within the disk surface. For example, the servo error signal gain change between recorded and unrecorded areas on the disc, the servo error signal gain change due to unevenness of reflectivity depending on the location of the disc, and tracking servo by push-pull signal In this case, the servo system can be kept at the design gain against the change of the servo gain due to the push-pull amplitude fluctuation.
Furthermore, the servo gain adjustment that is performed periodically, for example, during the operation execution period is a servo error detection method in which the servo error gain can be changed in the radial direction, such as the 3-spot method or the DPP method (differential push-pull method) In the case where it is adopted, it is possible to absorb the fluctuation of the servo error gain due to the movement in the radial direction.
In addition, when the servo gain is adjusted when the disk is loaded or during the operation execution period, it is possible to absorb the change in the servo gain due to the aging of the device.
[0067]
From the above, the present invention has the great effect of improving the servo performance of the disk drive device and thereby stabilizing the recording / reproducing operation.
[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 a block diagram of a configuration of a servo circuit according to the embodiment.
FIG. 3 is a block diagram of a configuration of a tracking servo calculation unit according to the embodiment.
FIG. 4 is an explanatory diagram of an adjustment source signal according to the embodiment.
FIG. 5 is a flowchart of servo gain adjustment processing according to the embodiment.
FIG. 6 is a flowchart of another servo gain adjustment process according to the embodiment.
[Explanation of symbols]
1 disk, 10 DSP, 11, 21 A / D converter, 12 focus servo calculation unit, 13, 23 D / A converter, 14 focus driver, 22 tracking servo calculation unit, 24 tracking driver, 30 memory unit, 41 addition 42, adjustment source signal generation unit, 43 servo processing unit, 44 filter unit, 45 response waveform measurement / gain calculation unit, 46 variable gain 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, 120 AV system

Claims (8)

Head means for performing laser irradiation and reflected light detection on a disk recording medium for writing or reading data;
Servo error signal generating means for generating a servo error signal from the reflected light obtained by the head means;
Servo signal generation means for performing predetermined processing including gain processing on the servo error signal to generate and output a servo signal;
Servo drive means for executing a servo operation of the head means based on a servo signal output from the servo signal generating means;
Adjustment source signal generating means capable of generating two different amplitude signals as the adjustment source signal of a specific frequency and adding the generated signal to the servo error signal;
Observation means for observing the amplitude of a servo loop response waveform generated by adding the adjustment source signal to the servo error signal;
Each amplitude of the two kinds of the adjustment source signals, and the servo loop response waveforms each amplitude of two types of the adjusting source signal corresponding to each amplitude when it is added to the servo error signal, a servo loop characteristic value Servo gain adjustment means for calculating the adjustment value of the servo loop gain by performing the calculation used, and adjusting the gain value in the gain processing of the servo signal generation means;
A control means for performing addition of each adjustment source signal of two different amplitudes to the servo error signal and observation of a servo loop response waveform at the same location or a nearby location on the disk recording medium ,
The servo gain adjustment means performs an operation of subtracting each servo loop response waveform observed corresponding to each amplitude when the two amplitudes of the adjustment source signal are added to the servo error signal. disk drive apparatus and performs. Storage means for storing the adjustment value calculated by the servo gain adjustment means,
The servo gain adjustment unit calculates an average value of the calculated adjustment value and a past adjustment value stored in the storage unit, and adjusts the gain value in the gain processing of the servo signal generation unit based on the average value. The disk drive device according to claim 1, wherein:   2. A control means for adjusting a gain value in the gain processing by the adjustment source signal generation means, the observation means, and the servo gain adjustment means when a disk recording medium is loaded. The disk drive device described in 1.   Control means for adjusting the gain value in the gain processing by the adjustment source signal generation means, the observation means, and the servo gain adjustment means at a predetermined timing in the operation execution period for the disk recording medium after the disk recording medium is loaded. The disk drive device according to claim 1, further comprising: A servo loop response waveform generated by generating two different amplitude signals as the adjustment source signal of a specific frequency and adding it to the servo error signal, and adding the adjustment source signal of each amplitude to the servo error signal. Observe the amplitude of
Each amplitude of the two kinds of the adjustment source signals, and the servo loop response waveforms each amplitude of two types of the adjusting source signal corresponding to each amplitude when it is added to the servo error signal, a servo loop characteristic value Calculate the adjustment value of the servo loop gain by performing the calculation used,
While adjusting the servo gain using the calculated adjustment value ,
Addition of each of the two different amplitude adjustment source signals to the servo error signal and observation of the servo loop response waveform are performed at the same location on the disk recording medium or at a nearby location ,
In calculating the adjustment value, the servo loop response waveforms observed corresponding to the respective amplitudes when the two amplitudes of the adjustment source signal are added to the servo error signal, A servo gain adjustment method including a subtraction operation . While storing the calculated adjustment value,
When the servo gain adjustment is according to claim 5, characterized in that calculating the adjustment value is the calculated, the average value of the stored adjustment values of the past, adjusting the servo gain by the average value Servo gain adjustment method. When a disk recording medium is loaded, generation of the adjustment source signal and addition to the servo error signal, observation of the servo loop response waveform, and calculation of the adjustment value are performed to adjust the servo gain. The servo gain adjusting method according to claim 5 , wherein the servo gain is adjusted. After the disk recording medium is loaded, the adjustment source signal is generated and added to the servo error signal, the servo loop response waveform is observed, and the adjustment value is calculated at a predetermined timing in the operation execution period for the disk recording medium. The servo gain adjustment method according to claim 5 , wherein the servo gain adjustment is executed.

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