JP2007066483A - Focus servo method, tracking servo method, and optical disk system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that optical crosstalk where tracking error signal components leak into focus error signal components occurs due to the deviation of the fitting balance of a photodetector, and mechanical crosstalk occurs from a focus actuator to a tracking actuator depending on the constitution of an actuator, so that focusing control and tracking servo control are affected. <P>SOLUTION: An optical disk drive system which performs the tracking control and the focusing control of an optical disk based on the tracking error signal and the focus error signal generated by reflected light of a beam with which an optical disk is irradiated is provided with a crosstalk canceller for cancelling optical crosstalk generated from a tracking error signal generation system to a focus error signal generation system; a means for measuring the optical crosstalk quantitively; and a means for obtaining a proper gain given to the cross canceller. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus that records and reproduces information on a recordable optical disc, and more particularly to a focus servo control technique for an optical disc.

  Optical disc devices such as audio CDs, CD-ROMs, CD-R / RWs, DVDs, BDs, etc. have already been put into practical use, and are actively developed for various applications and high performance. ing. Particularly recently, with the rapid market expansion of personal computers, the penetration rate of built-in optical disk devices in personal computers has increased.

  In an optical disc apparatus, in order to accurately record or reproduce information, it is necessary that the laser light applied to the optical disc accurately follows the track of the optical disc. This control is performed by generating a tracking error signal and controlling the tracking actuator by a tracking servo mechanism based on the tracking error signal.

  In addition, it is necessary for the laser light applied to the optical disc to be properly focused on the reflecting surface of the optical disc, and for that purpose, means for controlling the distance between the objective lens that collects the laser light and the optical disc is important. It becomes. This control is performed by generating a focus error signal and controlling the focus actuator by a focus servo mechanism based on the focus error signal.

  Here, the tracking error signal is a signal indicating a deviation in the optical disc radial direction between the light spot and the information track of the optical disc. The focus error signal is a signal indicating a shift in the focal direction between the light beam spot emitted from the objective lens provided in the optical pickup and the recording surface of the optical disc.

  The configuration of the optical disk apparatus will be described with reference to the block diagram of the conventional optical disk drive apparatus in FIG.

  In FIG. 8, the optical disc apparatus irradiates the optical disc 1 with laser light and receives the light reflected by the optical disc 1, and converts the reflected light from the optical disc 1 obtained by the optical pickup 7 into an electrical signal. Then, a photodetector 10 for outputting a signal for reading data from the optical disc 1, an output signal for detecting a focus error, and an output signal for detecting a tracking error, and a tracking error signal from an output signal output from the photodetector 10. (Hereinafter abbreviated as “TE signal”) and a front-end processor (hereinafter abbreviated as FEP) for generating a focus error signal (hereinafter abbreviated as “FE signal”) 11 Have

  The TE signal and the FE signal are input from the FEP to a digital servo processor (hereinafter abbreviated as “DSP”) 3. The DSP 3 controls an actuator driver 4 equipped with a drive means of a disk motor 2 that rotates the optical disk 1 and also tracking that drives the optical pickup 2 so that the optical pickup 2 follows the track of the optical disk 1 based on the TE signal. The actuator driver 4 equipped with driving means for operating the actuator 6 is controlled, and a traverse motor 8 that moves the optical pickup 7 in the radial direction of the optical disk 1 is controlled. Further, the actuator driver 4 equipped with driving means for operating the focus actuator is controlled so that the distance between the objective lens provided in the optical pickup 7 and the optical disk 1 is appropriate.

  The above processing of the DSP 3 is executed under the control of the CPU 9.

  Here, means for controlling the focus and tracking will be described with reference to the block diagram of the focus servo control system in the conventional optical disk drive apparatus of FIG. 9 and the block diagram of the tracking servo control system in the conventional optical disk drive apparatus of FIG.

  In FIG. 9, 12 is a focus servo filter, 4 is an actuator driver, and 13 is a focus actuator. The focus servo filter 12, the actuator driver 4, and the focus actuator 13 are a feedback control system that returns position information in the focus direction obtained from the focus actuator 13 to position information up to the optical disc recording surface, Based on the focus error signal, the focus servo filter 12 gives necessary gain and phase characteristics in a desired band, functions as a stable servo system without oscillating as a feedback control system of the focus servo, and the focus error signal Operates so that the deviation is below a certain level.

  Next, means for controlling tracking will be described with reference to FIG.

In FIG. 10, 14 is a tracking servo filter, 4 is an actuator driver, and 15 is a tracking actuator. The tracking servo filter 14, the actuator driver 4, and the tracking actuator 15 are a feedback control system that returns position information in the tracking direction obtained from the tracking actuator 15 to track position information, and the tracking error signal In the tracking servo filter 14, the necessary gain and phase characteristics in a desired band are given, and the tracking servo feedback control system functions as a stable servo system without oscillating, and the tracking error signal has a certain deviation or less. It works to be.
Japanese Unexamined Patent Publication No. 63-229627

  The reason why the focus and tracking servo loop system becomes unstable is when the optical crosstalk factor and the mechanical crosstalk factor occur at the same time, and by eliminating one of the factors, It is possible to prevent the focus and tracking servo control from becoming unstable. Here, the mechanical crosstalk factor can be reduced to some extent by devising the mechanical mechanism such as the arrangement of the magnets that make up the actuator, but it is compatible with the recent thinning typified by notebook computers. To do so, the mechanical mechanism is limited, making it difficult to respond. Further, the optical crosstalk factor can reduce the leakage of the track error signal by adjusting the mounting position of the photo detector, but the photo detector mounting variation and the adhesive used for mounting can be reduced. It is difficult to set the mounting position at which the leakage of the tracking error signal is minimized while maintaining the mounting balance accuracy due to the change over time due to curing of the film or the change due to temperature.

  Further, as described above, the servo system for controlling the focus actuator 5 in FIG. 8 and the servo system for controlling the tracking actuator 6 in FIG. 8 are independent individual system systems that interfere with each other. It is established on the assumption that there is no.

  However, mechanical crosstalk from the focus actuator 5 to the tracking actuator 6 occurs depending on the mechanical structure (not shown) of the focus actuator 5 and the tracking actuator 6 in FIG. Due to the presence of this mechanical crosstalk, the movement of the focus actuator in the focus direction (the direction in which the disc surface and the objective lens in the optical pickup are in focus) is moved in the tracking direction (the data string recorded spirally on the disc surface). Interference with the operation of the tracking actuator in the disk radial direction to follow).

  Further, when the positional deviation of the photodetector 10 in FIG. 8 occurs, optical crosstalk occurs from the tracking error signal to the focus error signal. Due to the presence of this optical crosstalk, the signal change of the tracking error signal interferes with the signal change of the focus error signal.

  Here, the mechanical crosstalk and the optical crosstalk are represented by a focus servo control system and a tracking servo control system using a diagram showing a crosstalk generation mechanism in the conventional optical disc drive apparatus of FIG. I will explain the impact of this.

  In FIG. 11, reference numeral 12 denotes the focus servo filter, which is denoted by the same reference numeral and description of its operation is omitted. Reference numeral 4 denotes an actuator driver, which is denoted by the same reference numeral and description thereof is omitted. Reference numeral 13 denotes a focus actuator, reference numeral 16 denotes the optical crosstalk, reference numeral 14 denotes a tracking servo filter, and the description thereof is omitted with the same reference numerals. Reference numeral 4 denotes an actuator driver, which is denoted by the same reference numeral and description of its operation is omitted. Reference numeral 15 denotes a tracking actuator, 17 denotes the mechanical crosstalk, 10 denotes the photodetector, and the same reference numerals are given and description of the operation is omitted. When the focus servo control system is performing the focus control operation, the focus servo filter 12, the actuator driver 4, and the focus actuator 13 form a feedback loop, and at the same time, the tracking servo control system performs the tracking control operation. The tracking servo filter 14, the actuator driver 4, and the tracking actuator 15 form a feedback loop, and the presence of mechanical crosstalk 17 from the focus actuator 13 to the tracking actuator 15 serves as position information crosstalk. , Bring transfer characteristics. Further, the presence of the optical crosstalk 16 provides transfer characteristics as crosstalk of error information from the tracking error signal (TE signal) to the focus error signal (FE signal), so that the focus servo control system which is the original loop is provided. In addition to the feedback loop system, a minor loop 18 is formed in the focus servo control system via a mechanical crosstalk 17, a tracking control loop, and an optical crosstalk 16, and the tracking servo control system Thus, a feedforward transfer function 18 is formed via the optical crosstalk 16, the focus servo filter 12, the actuator driver 4, and the focus actuator 13. Here, a graph showing characteristics when mechanical crosstalk is modeled in the conventional optical disk drive apparatus of FIG. 12 and the influence of the focus open loop characteristic due to mechanical crosstalk in the conventional optical disk drive apparatus of FIG. The influence of the minor loop 18 on the original focus loop characteristic and tracking servo loop characteristic will be described using the graph of the characteristic shown. The frequency characteristics when the mechanical crosstalk 17 is modeled are shown in FIG. 12, the optical crosstalk is modeled as a quantitative gain, and the focus servo open loop when the minor loop 18 is formed in the focus servo loop system. The characteristics are shown in FIG. In the mechanical crosstalk 17, as shown in FIG. 12, a resonant gain rise occurs in a specific frequency band, and the phase changes simultaneously. The gain and phase changes in the specific frequency band are changed to the original focus servo open loop characteristics and tracking servo open loop characteristics due to the presence of the minor loop / FW transmission system 18 formed through the optical crosstalk 16. The frequency band is affected by gain and phase deterioration, and the frequency band coincides with the specific frequency band in the mechanical crosstalk 17. Generally, the open loop characteristic is that the servo control system becomes unstable when the phase margin at the gain intersection (the point where the gain = 0 dB) falls below 30 degrees. In the focus servo control and tracking servo control designed by the focus servo filter 12 and the tracking servo filter 14, the phase deterioration is caused to 20 degrees or more with respect to the focus and tracking open loop characteristics, and the phase margin is originally 30 degrees or more. On the other hand, it causes excessive phase degradation and causes failure.

  Such a servo control technique is proposed in, for example, (Patent Document 1).

Therefore, in the optical disk drive device according to the present invention, by correcting the tracking servo control system from the tracking servo control system to the focus servo system so as to minimize the optical crosstalk generated from the tracking error signal to the focus error signal, correction is performed. A correction circuit (crosstalk canceller) for canceling the optical crosstalk component is provided, and a constant initial value gain sufficient to cancel the optical crosstalk is given to the crosstalk canceller in advance during the first servo operation. Due to insufficient phase margin by means of providing a gain sufficient to cancel the crosstalk from the result of measuring the residual component generated in the focus error signal when the focus servo control is on and the tracking servo control is off. Focus and The focus and tracking servo operations can be performed even when the racking servo operation is defective, and after the servo operation, the optical crosstalk amount is obtained by the means for calculating, and is adequate to sufficiently cancel the optical crosstalk. The main feature is that a stable gain and tracking servo characteristics can be realized by setting a large gain in the crosstalk canceller.

  In addition, when the tracking servo control is on, a disturbance signal having a frequency and amplitude that are outside the tracking and focus servo control band is added, and the resulting residual component of the focus servo control system is measured. It is possible to perform an accurate measurement of the optical crosstalk amount.

  As described above, the optical disc apparatus of the present invention can eliminate the formation of a minor loop formed via the tracking servo control system in the focus servo control system by canceling the optical crosstalk component. Phase degradation (drop) that occurs in focus servo control can be greatly improved, providing stable servo control and occurring due to the effects of optical crosstalk during tracking off and seeking. It is possible to obtain an optical disc apparatus capable of greatly reducing noise and current flowing through the focus actuator.

  In addition, when the tracking servo control is on, a disturbance signal having a frequency and amplitude that are outside the tracking and focus servo control band is added, and the resulting residual component of the focus servo control system is measured. Thus, an optical disc apparatus capable of accurately measuring the optical crosstalk amount can be obtained.

  An optical disc apparatus capable of giving a gain sufficient to cancel out crosstalk from a result of measuring a residual component generated in a focus error signal when the focus servo control is on and the tracking servo control is off. Can be obtained.

  The first invention made to solve the above-described problem is to perform tracking control and focus control of the optical disk based on the tracking error signal generated by the reflected light of the beam irradiated on the optical disk and the focus error signal. In an optical disc drive apparatus, a crosstalk canceller that cancels optical crosstalk generated from a tracking error signal generation system to a focus error signal generation system, means for quantitatively measuring the optical crosstalk, and An optical disc apparatus characterized by comprising means for obtaining an appropriate gain to be given to the crosstalk canceller. As a result, the optical crosstalk is canceled out, the deterioration of the focus servo phase characteristic is eliminated, and stable focus servo control can be provided.

  According to a second invention for solving the above-described problems, in the first invention, the tracking error signal generated by the reflected light of the beam irradiated on the optical disk, and the tracking control of the optical disk based on the focus error signal, In an optical disc drive apparatus that performs focus control, a crosstalk canceller that cancels optical crosstalk generated from the tracking error signal generation system to the focus error signal generation system, and quantitatively measures the optical crosstalk And a means for determining an appropriate gain to be given to the crosstalk canceller, whereby the optical crosstalk can be canceled out.

  According to a third aspect of the present invention for solving the above problems, in the first aspect, the tracking error signal generated by the reflected light of the beam irradiated on the optical disc and the tracking control of the optical disc based on the focus error signal In an optical disc drive apparatus that performs focus control, a crosstalk canceller that cancels optical crosstalk generated from the tracking error signal generation system to the focus error signal generation system, and quantitatively measures the optical crosstalk And a means for obtaining an appropriate gain to be given to the crosstalk canceller, whereby the optical crosstalk can be canceled.

  A fourth invention made to solve the above-mentioned problems is characterized in that the means for quantitatively measuring the optical crosstalk is obtained by adding a specific disturbance to the tracking servo control system. The optical disc apparatus according to claim 1.

  A fifth invention made to solve the above-mentioned problems is characterized in that the means for quantitatively measuring the optical crosstalk is obtained by adding a specific disturbance to the tracking servo control system. A focus servo method according to claim 2.

  A sixth invention made to solve the above-mentioned problems is characterized in that the means for quantitatively measuring the optical crosstalk is obtained by adding a specific disturbance to the tracking servo control system. A tracking servo method according to claim 3.

  A seventh invention made to solve the above-described problem is that the crosstalk canceller obtains an appropriate gain for giving the tracking error signal to the crosstalk canceller from the tracking error signal generation system to the focus error signal generation system. The optical disk apparatus according to claim 1, wherein the optical disk apparatus is obtained by:

  An eighth invention made to solve the above-mentioned problem is that the crosstalk canceller obtains an appropriate gain for giving the tracking error signal to the crosstalk canceller from the tracking error signal generation system to the focus error signal generation system. The focus servo method according to claim 2, wherein the focus servo method is obtained by:

  According to a ninth aspect of the invention made to solve the above-mentioned problem, the crosstalk canceller obtains an appropriate gain for giving the tracking error signal to the crosstalk canceller from the tracking error signal generation system to the focus error signal generation system. The tracking servo method according to claim 3, wherein the tracking servo method is obtained by:

  According to a tenth aspect of the present invention for solving the above-described problems, the means for obtaining an appropriate correction gain to be given to the crosstalk canceller is the optical cross obtained by the means for quantitatively obtaining the optical crosstalk. 2. The optical disc apparatus according to claim 1, wherein a cancel gain corresponding to a talk amount is given.

  According to an eleventh aspect of the invention for solving the above-described problems, the means for obtaining an appropriate correction gain to be given to the crosstalk canceller is the optical cross obtained by the means for quantitatively obtaining the optical crosstalk. 3. The focus servo method according to claim 2, wherein a cancel gain corresponding to the talk amount is given.

  According to a twelfth aspect of the present invention, the means for obtaining an appropriate correction gain to be given to the crosstalk canceller is an optical cross obtained by means for quantitatively obtaining the optical crosstalk. 4. The tracking servo method according to claim 3, wherein a cancel gain corresponding to a talk amount is given.

  According to a thirteenth aspect of the present invention for solving the above problems, the means for quantitatively measuring the optical crosstalk includes a tracking error signal that changes by applying a specific disturbance to the tracking servo control system. 2. The optical disc apparatus according to claim 1, wherein a change in the focus error signal with respect to a change in the tracking error signal obtained by detecting the focus error signal at the set timing is obtained.

  According to a fourteenth aspect of the present invention, the means for quantitatively measuring the optical crosstalk is a tracking error signal that changes by applying a specific disturbance to the tracking servo control system. 3. The focus servo method according to claim 2, wherein a change in the focus error signal with respect to a change in the tracking error signal obtained by detecting the focus error signal at a set timing is obtained.

  According to a fifteenth aspect of the present invention, there is provided a fifteenth aspect of the invention in which the means for quantitatively measuring the optical crosstalk is a tracking error signal that changes by applying a specific disturbance to the tracking servo control system. 4. The tracking servo method according to claim 3, wherein a change in the focus error signal with respect to a change in the tracking error signal obtained by detecting the focus error signal at a set timing is obtained.

  The sixteenth invention made to solve the above-mentioned problem is characterized in that the correction gain is set when the crosstalk canceller is equal to or more than a set optical crosstalk threshold. This is an optical disc device.

  The seventeenth invention made to solve the above-mentioned problems is characterized in that the correction gain is set when the crosstalk canceller becomes equal to or more than a set optical crosstalk threshold. It is a focus servo method described in the above.

  An eighteenth invention made to solve the above-mentioned problem is characterized in that the correction gain is set when the crosstalk canceller is equal to or more than a set optical crosstalk threshold. Is a tracking servo method.

  A nineteenth invention made to solve the above-mentioned problem is characterized in that a constant value is set in advance as an initial value for an appropriate correction gain to be given to the crosstalk canceller that cancels the optical crosstalk amount. Thus, the focus servo can be pulled in even when the influence of the optical crosstalk occurs.

  A twentieth invention made to solve the above-mentioned problem is characterized in that a constant value is set in advance as an initial value for an appropriate correction gain to be given to the crosstalk canceller that cancels the optical crosstalk amount. The focus servo method according to claim 2, wherein the focus servo can be pulled in even when the influence of the optical crosstalk occurs.

  A twenty-first invention made to solve the above-mentioned problems is characterized in that a constant value is set in advance as an initial value for an appropriate correction gain to be given to the crosstalk canceller that cancels the optical crosstalk amount. The tracking servo method according to claim 3, wherein the tracking servo can be pulled in even when the influence of the optical crosstalk occurs.

  In a twenty-second aspect of the invention made to solve the above problems, the crosstalk canceller is set in order to reduce phase deterioration of servo characteristics caused by the optical crosstalk and the mechanical crosstalk. 2. The optical disk apparatus according to claim 1, wherein a gain intersection between the focus servo gain and the tracking servo gain is deviated before the step of the step, so that the optical crosstalk is applied to the focus servo. Can reduce the effect.

  In a twenty-third aspect of the invention made to solve the above problems, the crosstalk canceller is set in order to reduce phase deterioration of servo characteristics caused by the optical crosstalk and the mechanical crosstalk. 3. The focus servo method according to claim 2, wherein the gain crossing point between the focus servo gain and the tracking servo gain is deviated before the step, so that the optical crosstalk is reduced by the focus servo. Can reduce the impact on

  In a twenty-fourth aspect of the invention made to solve the above problems, the crosstalk canceller is set in order to reduce phase deterioration of servo characteristics caused by the optical crosstalk and the mechanical crosstalk. The tracking servo method according to claim 3, wherein the gain crossing point between the focus servo gain and the tracking servo gain is deviated before the step of the tracking servo gain. Can reduce the impact on

  According to a twenty-fifth aspect of the present invention, the second means for quantitatively measuring the optical crosstalk is a focus error that changes when the tracking servo control system is not operating. 2. The optical disc apparatus according to claim 1, wherein the optical crosstalk amount is obtained by measuring the amount of optical crosstalk even when the tracking servo is in an uncontrolled state. Since an appropriate gain is set in the talk canceller, it is possible to provide stable tracking servo control even when tracking servo control cannot be operated due to the influence of the crosstalk, and before the formation of the minor loop, 2. The optical disk apparatus according to claim 1, wherein a stable focus servo can be provided.

  According to a twenty-sixth aspect of the present invention, the second means for quantitatively measuring the optical crosstalk is a focus error that changes when the tracking servo control system is not operating. 3. The focus servo method according to claim 2, wherein the focus servo method is obtained by measuring an amplitude amount of the signal, whereby the optical crosstalk amount is measured even when the tracking servo is in an uncontrolled state. It is possible to set an appropriate gain for the crosstalk canceller, provide stable focus servo control even when tracking servo control cannot be operated due to the influence of the crosstalk, and before forming the minor loop. The focus according to claim 2, wherein a stable focus servo can be provided. Servo method.

  According to a twenty-seventh aspect of the present invention, the second means for quantitatively measuring the optical crosstalk is a focus error that changes when the tracking servo control system is not operating. 3. The tracking servo method according to claim 2, wherein the tracking servo method is obtained by measuring an amplitude amount of the signal, whereby the optical crosstalk amount is measured even when the tracking servo is in an uncontrolled state. It is possible to provide an appropriate gain for the crosstalk canceller, provide stable tracking servo control even when tracking servo control cannot be operated due to the influence of the crosstalk, and before the minor loop is formed. Therefore, it is possible to provide a stable focus servo. King servo method.

(Embodiment 1)
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram according to the first embodiment of the present invention, FIG. 2 is a detailed block diagram of an eccentricity detecting unit according to the first embodiment, and FIG. 3 is an optical crosstalk detecting unit according to the first embodiment of the present invention. FIG. In FIG. 1, 12 is a focus servo filter, 4 is an actuator driver, 14 is a tracking servo filter, 4 is an actuator driver, 15 is a tracking actuator, 16 is optical crosstalk, 17 is mechanical crosstalk, and 18 is a minor loop. The above is the same configuration as the servo control system of the conventional optical disk drive, and the same reference numerals are given to omit redundant description. A crosstalk canceller 19 cancels the optical crosstalk 16. The crosstalk canceller 19 functions to prevent the minor loop 18 from being formed by setting a gain corresponding to the optical crosstalk 16, and a phase generated in the focus servo phase characteristic. The effect of greatly improving the decline of the

  Next, a method for measuring the amount of the optical crosstalk 16 will be described with reference to FIGS. In FIG. 2, 16 is the optical crosstalk, and 20 is a disturbance applying unit showing a portion where a disturbance is applied. In FIG. 2, the disturbance applied to the tracking servo loop system is optically transmitted to the FE signal by the optical crosstalk 16. Here, the first method for obtaining the optical crosstalk amount by the applied disturbance will be described with reference to FIG. In FIG. 3, 21 is a disturbance signal, 22 is a TE signal, and 23 is an FE signal. The disturbance signal 21 is given as a rectangular waveform signal in the focus control state and the tracking control state. The TE signal 22 and the FE signal 23 change according to the change in the applied disturbance signal 21, and the maximum displacement occurs after a certain time (Tm) from the rising and falling edges of the rectangular waveform signal as the disturbance signal 21. And the minimum displacement point is generated. The TE signal displacement value after the Tm time at an arbitrary timing from the rising edge of the disturbance signal 21 is TEr [n], the FE signal displacement is FEr [n], and the arbitrary timing from the falling edge of the disturbance signal 21. Assuming that the TE signal displacement after Tm time is TEf [n] and the FE signal displacement is FEf [n], the amount of displacement (optical crosstalk amount) exerted by the TE signal on the FE signal is as follows: Become.

Optical crosstalk amount = Σ ((FEr [n] −FEf [n]) / (TEr [n] −TEf [n]))
The optical crosstalk amount obtained by the above equation can also determine the phase relationship between the TE signal and the FE signal from the calculated code relationship.

  Next, with respect to the method of calculating the gain given to the crosstalk canceller 19 from the optical crosstalk amount obtained as described above, the Gα calculation graph in the first embodiment of the present invention shown in FIG. 4 and the present invention shown in FIG. This will be described using the Gα calculation graph in the first embodiment. In FIG. 4, 24 is an approximate line for obtaining the gain set in the crosstalk canceller 19, 25 is a first measurement point, 26 is a second measurement point, and 27 is an optical crosstalk. 28 is a correction gain (hereinafter also abbreviated as Gα) set to the crosstalk canceller.

  First, an appropriate initial value that does not cause excessive correction is given to Gα28, and Crs27 is measured by the measurement method described above. Since it has already been clarified that Gα28 and Crs27 have a primary correlation, Crs27 is 0 (first approximation line 24) from the first measurement point 25 measured by giving to Gα28 as an initial value. Gα28 that becomes zero) can be easily obtained.

  The case where the result of measuring Crs 27 in Gα 28 obtained from the approximate line 24 is not within the preset threshold 29 will be described with reference to FIG. In FIG. 5, a value obtained by multiplying the Gα28 by a preset ratio is set in the Gα28, and this is set as the third measurement point. Next, Gα28 at which Crs27 is 0 (zero) can be obtained from the two linear approximation lines (24a) obtained from the second measurement point and the third measurement point, and the calculation convergence accuracy of Gα can be improved.

  Next, the second means for obtaining the optical crosstalk amount will be described with reference to the block diagram of the optical crosstalk detecting means in the first embodiment of the present invention shown in FIG. In FIG. 6, 12 is a focus servo filter, 4 is an actuator driver, 13 is a focus actuator, 14 is a tracking servo filter, 4 is an actuator driver, 15 is a tracking actuator, 16 is Optical crosstalk. Since the above blocks have already been described, the same reference numerals are given and repeated description will be omitted. 30 is a tracking error signal, and 31 is a focus error signal. Here, in FIG. 6, the tracking servo control system is in a non-operating state, and the tracking servo loop is not closed. At this time, since the focus servo control system is in an operating state, only control for focusing on the optical disk surface is performed. For this reason, a signal such as a tracking error signal 30 crossing a track formed on the disk is generated due to the eccentricity of the disk or a turntable (not shown) on which the disk is mounted. Further, due to the presence of the optical crosstalk 16, the signal component of the tracking error signal 30 appears like a focus error signal 31. By measuring the signal amplitude of the focus error signal 31, the optical crosstalk 16 can be obtained. However, in this case, the phase relationship between the tracking error signal and the focus error signal cannot be obtained. Since the optical crosstalk 16 obtained as described above has a linear function correlation with Gα28, as in the first method for obtaining the optical crosstalk amount, the optical crosstalk amount. From the focus error signal amplitude obtained by the second method for obtaining the above, the value of the coarse Gα that can substantially cancel the optical crosstalk amount can be derived by a primary approximation line.

(Embodiment 2)
Next, with respect to the second embodiment, a means for setting a gain to be given to the crosstalk canceller 19 will be described using the Gα calculation flowchart in the second embodiment of the present invention shown in FIG. In FIG. 7, the processes from S1 to S22 are controlled by a CPU (9 in FIG. 8) and a DSP (3 in FIG. 8) in the optical disk drive apparatus.

  When the optical disk is loaded in the optical disk drive device, the startup process starts (S1).

  After the start-up process is started and settings and adjustment processes necessary for operating the focus servo control such as the RF signal system and the servo signal system are performed, the focus servo control operates (S2).

  Next, after setting and adjustment processing necessary to operate tracking servo control such as normalization processing and balance adjustment to set the tracking error signal to a constant amplitude level, tracking error at tracking off The optical crosstalk amount from the signal is obtained by measuring the FE signal amplitude (S3).

  Next, from the FE signal amplitude obtained in (S3), the coarse Gα capable of approximately canceling the optical crosstalk amount is calculated by the second method for obtaining the optical crosstalk amount ( S4), the crosstalk canceller 19 is set (S5).

  After the coarse Gα is set in the crosstalk canceller 19, the tracking servo is turned on (S6). Next, it is determined whether the tracking servo is turned on (S7). If the tracking servo control is not turned on, the tracking servo control is turned on. The polarity of the coarse Gα is reversed and set to the crosstalk canceller 19 again (S8).

  Here, since the optical crosstalk amount is canceled by the setting of Gα and the servo phase characteristic deterioration is reduced, the servo operates even when the tracking servo control loop is closed (Tr servo ON (S6)). It should be. Here, it is determined again whether or not the tracking servo has been turned on (S9). If tracking pull-in has failed, it is determined that the cause is other than optical crosstalk, and is sent to the host PC (not shown). An error is returned (S10) and the process ends.

  In the tracking pull-in determination in (S7) and (S9), if it is determined that the tracking servo is on, the disturbance signal necessary for the first method for measuring the optical crosstalk amount performed while the tracking servo is on is generated. In order to provide it, the frequency and amplitude are set (S11).

  Next, the first method for measuring the optical crosstalk amount is different from the calculation result of the optical crosstalk amount depending on the tracking and focus servo characteristics. This is performed after the servo gain learning process that achieves the servo characteristics as desired (S12).

  Next, in the rough Gα setting state, the optical crosstalk amount Crs at the first point when the tracking servo control is turned on is measured by the first method for measuring the optical crosstalk amount (S13). ).

  Next, in the threshold determination (S14), if the optical crosstalk amount Crs measured in (S13) is less than the set threshold, the optical crosstalk amount has already been sufficiently canceled ( Alternatively, it is determined that the amount of optical crosstalk is low, and the setting of Gα is completed (S22).

  Further, if the optical crosstalk amount Crs measured in (S13) is equal to or larger than a set threshold value, the first approximation line is obtained by the first method for measuring the optical crosstalk amount. To calculate Gα at which the optical crosstalk amount becomes 0 (zero) (S15).

  Next, the optical crosstalk amount Crs when Gα obtained in the second measurement point (S15) is set in the crosstalk canceller 19 is measured (S16).

  Next, in the threshold determination (S17), if the optical crosstalk amount Crs measured in (S16) is less than the set threshold, it is determined that an appropriate gain is set in the crosstalk canceller 19. Then, the setting of Gα is completed (S22).

  In the threshold determination (S17), if the optical crosstalk amount Crs measured in (S16) is equal to or greater than a set threshold, the optical crosstalk amount Crs measured in Gα in (S13). (First measurement point) and linear approximation from two points of the optical crosstalk amount Crs (second measurement point) measured by Gα in (S16) to obtain the optical crosstalk amount By this method, Gα at which the optical crosstalk amount becomes 0 (zero) is calculated (S17a).

  Next, the optical crosstalk amount Crs when Gα obtained in the third measurement point (S17a) is set in the crosstalk canceller 19 (S18) is measured (S17b).

  Next, in the threshold determination (S17c), if the optical crosstalk amount Crs measured in (S17b) is less than the set threshold, it is determined that an appropriate gain is set in the crosstalk canceller 19. Then, the setting of Gα is completed (S22).

  In the threshold determination (S17c), if the optical crosstalk amount Crs measured in (S17b) is equal to or larger than the set threshold value, the optical crosstalk amount Crs (measured in G16 in (S16)). First approximation is performed by performing linear approximation from two points of the second measurement point) and the optical crosstalk amount Crs (third measurement point) measured by Gα in (S18) to obtain the optical crosstalk amount. By this method, Gα at which the optical crosstalk amount becomes 0 (zero) is calculated (S19).

  Next, the optical crosstalk amount Crs when Gα obtained at the fourth measurement point (S19) is set in the crosstalk canceller 19 (S17d) is measured (S20).

  Next, in the threshold determination (S21), if the optical crosstalk amount Crs measured in (S20) is less than the set threshold, it is determined that an appropriate gain is set in the crosstalk canceller 19. Then, the setting of Gα is completed (S22).

  Further, in the threshold determination (S21), if the optical crosstalk amount measured in (S20) is equal to or larger than the set threshold, an appropriate gain setting for canceling the optical crosstalk cannot be performed. It is determined that the error has occurred, and an error is returned to the host PC (S23).

  By canceling the optical crosstalk from the tracking error signal to the focus error signal by the method as described above, stable focus control and tracking control can be performed, and the focus actuator is unnecessarily consumed. It is possible to reduce electric power and to suppress noise generated due to optical crosstalk.

  The present invention provides stable focus control and tracking even when mechanical crosstalk that the focus actuator exerts on the tracking actuator occurs or when optical crosstalk that occurs from the tracking error signal to the focus error signal occurs. An optical disc apparatus that can perform control and can reduce power consumed unnecessarily by the actuator due to the influence of optical crosstalk, and can also suppress noise generated due to the influence of optical crosstalk. Can be applied.

Configuration diagram of an optical crosstalk canceller in Embodiment 1 of the present invention Configuration diagram of optical crosstalk in Embodiment 1 of the present invention Configuration diagram of optical crosstalk detecting means in the first embodiment of the present invention Gα calculation graph in Embodiment 1 of the present invention Gα calculation graph in Embodiment 1 of the present invention Configuration diagram of optical crosstalk detecting means in the first embodiment of the present invention Gα calculation flowchart in Embodiment 2 of the present invention Configuration diagram of a conventional optical disk drive device Configuration diagram of focus servo control system in conventional optical disk drive Configuration diagram of tracking servo control system in conventional optical disk drive The figure which showed the crosstalk occurrence mechanism in the conventional optical disk drive device Graph showing characteristics when mechanical crosstalk is modeled in a conventional optical disk drive Characteristic graph showing the effect of focus open loop characteristics due to mechanical crosstalk in a conventional optical disk drive

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Disc motor 3 Digital Signal Processor (optical disk controller) part 4 Actuator driver 5 Focus actuator 6 Tracking actuator 7 Optical pick-up 8 Traverse motor 9 CPU
10 Photodetector 11 FEP (Signal operation unit)
DESCRIPTION OF SYMBOLS 12 Focus servo filter 13 Focus actuator 14 Tracking servo filter 15 Tracking actuator 16 Optical crosstalk 17 Mechanical crosstalk 18 Minor loop 19 Crosstalk canceller 20 Disturbance application part 21 Disturbance signal 22 TE signal by the disturbance application at the time of Tr-on Waveform 23 FE signal waveform due to disturbance applied when Tr is turned on 24 Approximate line 24a Two-point approximate line by second measurement point and third measurement point 25 First measurement point 26 Second measurement point 27 Crs (optical crosstalk amount)
28 Gα (gain given to crosstalk canceller)
29 Threshold 30 TE signal waveform at tracking off 31 FE signal waveform at tracking off

Claims (27)

Focus error signal generation system from tracking error signal generation system in optical disk drive apparatus that performs tracking control and focus control of optical disk based on tracking error signal generated by reflected light of beam irradiated to optical disk and focus error signal A crosstalk canceller that cancels out the optical crosstalk generated in the device, means for quantitatively measuring the optical crosstalk, and means for obtaining an appropriate gain to be given to the crosstalk canceller. An optical disc apparatus characterized by the above. Focus error signal generation system from tracking error signal generation system in optical disk drive apparatus that performs tracking control and focus control of optical disk based on tracking error signal generated by reflected light of beam irradiated to optical disk and focus error signal A crosstalk canceller that cancels out the optical crosstalk generated in the device, means for quantitatively measuring the optical crosstalk, and means for obtaining an appropriate gain to be given to the crosstalk canceller. Focus servo method characterized by Focus error signal generation system from tracking error signal generation system in optical disk drive apparatus that performs tracking control and focus control of optical disk based on tracking error signal generated by reflected light of beam irradiated to optical disk and focus error signal A crosstalk canceller that cancels out the optical crosstalk generated in the device, means for quantitatively measuring the optical crosstalk, and means for obtaining an appropriate gain to be given to the crosstalk canceller. A tracking servo method characterized by 2. The optical disc apparatus according to claim 1, wherein the means for quantitatively measuring the optical crosstalk is obtained by applying a specific disturbance to the tracking servo control system. 3. The focus servo method according to claim 2, wherein the means for quantitatively measuring the optical crosstalk is obtained by applying a specific disturbance to the tracking servo control system. 4. The tracking servo method according to claim 3, wherein the means for quantitatively measuring the optical crosstalk is obtained by adding a specific disturbance to the tracking servo control system. 2. The optical disc apparatus according to claim 1, wherein the crosstalk canceller obtains an appropriate gain for giving the tracking error signal to the crosstalk canceller from the tracking error signal generation system to the focus error signal generation system. 3. The focus servo method according to claim 2, wherein the crosstalk canceller obtains an appropriate gain for giving the tracking error signal to the crosstalk canceller from the tracking error signal generation system to the focus error signal generation system. . 4. The tracking servo method according to claim 3, wherein the crosstalk canceller obtains an appropriate gain to be given to the crosstalk canceller from the tracking error signal generation system to the focus error signal generation system. . The means for obtaining an appropriate correction gain to be given to the crosstalk canceller gives a cancellation gain corresponding to the optical crosstalk amount obtained by the means for quantitatively obtaining the optical crosstalk. 1. Optical disk apparatus of 1. The means for obtaining an appropriate correction gain to be given to the crosstalk canceller gives a cancellation gain corresponding to the optical crosstalk amount obtained by the means for quantitatively obtaining the optical crosstalk. 2. The focus servo method according to 2. The means for obtaining an appropriate correction gain to be given to the crosstalk canceller gives a cancellation gain corresponding to the optical crosstalk amount obtained by the means for quantitatively obtaining the optical crosstalk. 3. The tracking servo method according to 3. The first means for quantitatively measuring the optical crosstalk is to apply a specific disturbance to the tracking servo control system and detect the tracking error signal that changes and the focus error signal at the set timing. 2. The optical disc apparatus according to claim 1, wherein a change in the focus error signal with respect to a change in the tracking error signal obtained by the step is obtained. The first means for quantitatively measuring the optical crosstalk is to apply a specific disturbance to the tracking servo control system and detect the tracking error signal that changes and the focus error signal at the set timing. 3. The focus servo method according to claim 2, wherein a change amount of the focus error signal with respect to the change of the tracking error signal obtained by the step is obtained. The first means for quantitatively measuring the optical crosstalk is to apply a specific disturbance to the tracking servo control system and detect the tracking error signal that changes and the focus error signal at the set timing. 4. The tracking servo method according to claim 3, wherein a change amount of the focus error signal with respect to the change of the tracking error signal obtained by the step is obtained. 2. The optical disc apparatus according to claim 1, wherein the crosstalk canceller sets the correction gain when the optical crosstalk exceeds a set threshold value. 3. The focus servo method according to claim 2, wherein the correction gain is set when the crosstalk canceller is equal to or more than a set optical crosstalk threshold. 4. The tracking servo method according to claim 3, wherein the correction gain is set when the crosstalk canceller is equal to or more than a set optical crosstalk threshold. 2. The optical disc apparatus according to claim 1, wherein a constant value is set in advance as an initial value for an appropriate correction gain to be given to the crosstalk canceller that cancels the optical crosstalk amount. 3. The focus servo method according to claim 2, wherein a constant value is set in advance as an initial value for an appropriate correction gain to be given to the crosstalk canceller that cancels the optical crosstalk amount. 4. The tracking servo method according to claim 3, wherein a constant value is set in advance as an initial value for an appropriate correction gain to be given to the crosstalk canceller that cancels the optical crosstalk amount. In order to reduce the phase deterioration of the servo characteristics caused by the optical crosstalk and the mechanical crosstalk, before the crosstalk canceller is set, the focus servo gain and the tracking servo gain are 2. The optical disc apparatus according to claim 1, wherein gain intersections are separated. In order to reduce the phase deterioration of the servo characteristics caused by the optical crosstalk and the mechanical crosstalk, before the crosstalk canceller is set, the focus servo gain and the tracking servo gain are 3. The focus servo method according to claim 2, wherein gain intersections are separated. In order to reduce the phase deterioration of the servo characteristics caused by the optical crosstalk and the mechanical crosstalk, before the crosstalk canceller is set, the focus servo gain and the tracking servo gain are The tracking servo method according to claim 3, wherein gain intersections are separated. The second means for quantitatively measuring the optical crosstalk is obtained by measuring the amount of amplitude of the focus error signal that changes when the tracking servo control system is not operating. Item 1. The optical disk device according to Item 1. The second means for quantitatively measuring the optical crosstalk is obtained by measuring the amount of amplitude of the focus error signal that changes when the tracking servo control system is not operating. Item 3. The focus servo method according to Item 2. The second means for quantitatively measuring the optical crosstalk is obtained by measuring the amount of amplitude of the focus error signal that changes when the tracking servo control system is not operating. 4. The tracking servo method according to item 3.

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