JP4170361B2 - Correction parameter generation apparatus and aberration correction apparatus, correction parameter generation method and aberration correction method, correction parameter generation program, and aberration correction program - Google Patents

Description

【Technical field】
[0001]
  The present application belongs to the technical field of a correction parameter generation device and an aberration correction device, a correction parameter generation method and an aberration correction method, and a correction parameter generation program and an aberration correction program. Correction parameter generating apparatus, correction parameter generating method, correction parameter generating program, and generated correction for generating correction parameters for correcting spherical aberration particularly generated in a light beam used for recording and reproducing information The present invention belongs to the technical field of an aberration correction apparatus, an aberration correction method, and an aberration correction program that correct spherical aberration using parameters.
[Background]
[0002]
  In recent years, recording / reproduction of optical information using an optical disk is shifting to the direction of using a recording medium with a larger capacity, and along with this, the shortening of the wavelength of the light beam and the increase in the numerical aperture are remarkable. It has become.
[0003]
  Here, in general, in information recording / reproduction using a light beam, various aberrations occur particularly in the light beam itself. However, as described above, the tendency to shorten the wavelength and increase the numerical aperture is remarkable. Therefore, the influence of so-called spherical aberration is becoming prominent among these aberrations.
[0004]
  It is known that when this spherical aberration increases, the recording pit on the optical disk is downsized and the signal-to-noise ratio of the detection signal from the recording pit is adversely affected. As one of the correction methods on the optical path of the beam, a spherical aberration error signal directly indicating the spherical aberration is separately generated, and an optical system is set so that the spherical aberration error signal is minimized. . However, when this method is used, it is necessary to separately provide a configuration for generating a spherical aberration error signal in the pickup, which complicates the configuration of the pickup itself and increases the manufacturing cost.
[0005]
  Therefore, as a method for correcting spherical aberration without changing the configuration of an existing pickup as much as possible, for example, as shown in Patent Document 1 below, a jitter component included in a detection signal is detected, and a spherical surface is used so as to minimize it. There is a method for correcting aberrations.
[0006]
  In addition to the technique described in Patent Document 1, for example, a technique for detecting the amplitude of the tracking error signal and correcting the spherical aberration so as to maximize it, and the shape of the S-shaped signal as the focus error signal A technique for correcting spherical aberration so as to detect and correct the bias itself, or a technique for correcting spherical aberration so as to detect the amplitude of the S-shaped signal and maximize it has been developed. Yes.
[Patent Document 1]
JP 2004-629381 A
DISCLOSURE OF THE INVENTION
[Problems to be solved by the invention]
[0007]
  However, according to the method described in Patent Document 1, in order to detect the jitter component in the detection signal, some information must be recorded in advance on the optical disc. There is a problem in that unnecessary time is required before actually recording / reproducing information to / from the optical disc, and correction parameters for correcting spherical aberration cannot be acquired in advance on an unrecorded optical disc. Furthermore, even when the correction parameter is acquired by performing test recording, it is necessary to execute an accurate tracking servo during the acquisition, and the tracking servo may be interrupted, for example, the stability is lacking. There was also a point.
[0008]
  Further, in the technique of correcting the spherical aberration so as to detect the amplitude of the tracking error signal and maximize it, correction parameters can be obtained even when information is not recorded on the optical disc. A large amount of interference with the focus target value in the focus servo that is executed in parallel (that is, the amount of correction for spherical aberration so that the amplitude of the tracking error signal becomes maximum depending on the focus target value at that time) In order to obtain the optimum correction amount of spherical aberration, it is necessary to adjust the two parameters of the focus target value and the amplitude value of the tracking error signal two-dimensionally. This leads to the problem of increasing complexity.
[0009]
  Further, in the technique of correcting the spherical aberration by detecting the deviation of the shape of the S-shaped signal as the focus error signal and its amplitude, the light beam condensing position on the optical disc is generally perpendicular to the information recording surface of the optical disc. There is a problem that it is necessary to scan in a large direction, and it takes a long time to acquire a parameter for correcting spherical aberration, and the objective lens may collide with the optical disk during the scanning.
[0010]
  Therefore, the present application has been made in view of the above problems, and an example of the purpose is that even if information is not recorded on the recording medium or tracking servo is not executed. The necessary correction parameters can be acquired, the necessary correction parameters can be acquired while preventing the objective lens from colliding with the recording medium, and the necessary correction parameters can be set without making a major configuration change to the conventional pickup or the like. Provided are a correction parameter generation device, a correction parameter generation method, a correction parameter generation program, an aberration correction device that corrects spherical aberration using the generated correction parameter, an aberration correction method, and an aberration correction program. There is to do.
[Means for Solving the Problems]
[0011]
  In order to solve the above-described problems, the invention described in claim 1 is used to correct spherical aberration that occurs when at least one of recording and reproduction of information using a light beam with respect to a recording medium. In the correction parameter generation device for generating the correction parameter to be generated, servo loop control means for closing a focus servo loop for performing focus servo for the light beam condensing position, and the focus servo loop being closed During this time, a disturbance signal having a preset frequency and amplitude is electrically injected into the focus servo loop, and any electric signal in the focus servo loop into which the disturbance signal is electrically injected is disturbed. Disturbance injection means for extracting as an injection signal and while the focus servo loop is in a closed state Sensitivity detection means for detecting the sensitivity of the focus error signal obtained by changing the correction parameter corresponding to the changed correction parameter, and the correction parameter when the sensitivity is maximized, the spherical aberration Parameter determining means that is used as a correction parameter that is actually used to correct the disturbance signal, and the frequency of the disturbance signal is outside the frequency band used for the focus servo, and the amplitude of the focus error signal is set in advance. The frequency is over the set value.And the sensitivity detection means compares the phase of the disturbance injection signal obtained while the focus servo loop is in a closed state with the phase of the disturbance signal, and the phase of the disturbance injection signal with respect to the disturbance signal. A phase comparison unit that outputs a delay amount as the sensitivity, and the parameter determination unit sets the correction parameter when the phase delay amount is minimized to the correction parameter actually used for correcting the spherical aberration; It is characterized by.
[0012]
  In order to solve the above problem, the invention described in claim 2 corrects the spherical aberration by using the correction parameter generation device according to claim 1 and the correction parameter determined by the parameter determination means. And an aberration correction apparatus comprising: a correction unit;.
[0013]
  In order to solve the above-mentioned problems, the invention described in claim 3 is used to correct spherical aberration that occurs when at least one of recording and reproduction of information using a light beam with respect to a recording medium. In a correction parameter generation method for generating a correction parameter to be generated, a servo loop control step for closing a focus servo loop for performing focus servo with respect to a condensing position of the light beam, and the focus servo loop being closed During this time, a disturbance signal having a preset frequency and amplitude is electrically injected into the focus servo loop, and any electric signal in the focus servo loop into which the disturbance signal is electrically injected is disturbed. Disturbance injection process to extract as an injection signal and while the focus servo loop is closed A sensitivity detection step of detecting the sensitivity of the focus error signal obtained by changing the correction parameter corresponding to the changed correction parameter, and the correction parameter when the sensitivity is maximized are the spherical aberration. A parameter determining step as the correction parameter that is actually used for correction of the disturbance signal, the frequency of the disturbance signal is outside the frequency band used for the focus servo, and the amplitude of the focus error signal is previously The sensitivity detection step compares the phase of the disturbance injection signal obtained while the focus servo loop is in a closed state with the phase of the disturbance signal. A phase comparison step of outputting, as the sensitivity, a phase delay amount of the disturbance injection signal with respect to the disturbance signal, Parameter determination means, the correction parameters when the phase delay is minimized, characterized in that the said correction parameter actually used for the correction of the spherical aberration.
[0014]
  In order to solve the above-described problem, the invention described in claim 4 is a correction parameter generation method according to claim 3 and correction for correcting the spherical aberration using the correction parameter determined in the parameter determination step. And a process.
[0015]
  In order to solve the above-mentioned problem, the invention described in claim 5 is used to correct spherical aberration that occurs when at least one of recording and reproduction of information using a light beam with respect to a recording medium. A correction parameter generation computer included in a correction parameter generation device that generates a correction parameter includes: a servo loop control unit that closes a focus servo loop for performing focus servo with respect to the light beam focusing position; and the focus servo loop includes: While in the closed state, a disturbance signal having a preset frequency and amplitude is electrically injected into the focus servo loop, and any of the focus servo loops into which the disturbance signal is electrically injected Disturbance injection means for extracting the electric signal of the signal as a disturbance injection signal Sensitivity detection means for detecting the sensitivity of the focus error signal obtained by changing the correction parameter while the loop is in a closed state, corresponding to the changed correction parameter, and the sensitivity is maximum A correction parameter generation program that functions as a parameter determination unit that uses the correction parameter as the correction parameter that is actually used for correcting the spherical aberration, and the frequency of the disturbance signal is the focus parameter The correction parameter generation computer that is outside the frequency band used for the servo and has a frequency at which the amplitude of the focus error signal is equal to or higher than a preset value and functions as the sensitivity detection unit, Phase of the disturbance injection signal obtained while the servo loop is closed A correction parameter generating computer that compares the phase of the disturbance signal with each other, functions as a phase comparison unit that outputs a phase delay amount of the disturbance injection signal with respect to the disturbance signal as the sensitivity, and further functions as the parameter determination unit; The correction parameter when the phase delay amount is minimized is made to function so as to be the correction parameter actually used for correcting the spherical aberration.
[0016]
  In order to solve the above problems, the claims6The invention described in claim2A computer included in the aberration correction apparatus described in (1) is caused to function as the correction unit.
[0017]
  Next, the best mode for carrying out the present application will be described with reference to the drawings. Each embodiment described below generates a correction parameter for correcting spherical aberration generated in a recording / reproducing light beam when information is recorded or reproduced on an optical disc as a recording medium. This is an embodiment when the present application is applied to a spherical aberration correction apparatus including a correction parameter correction apparatus.
[0018]
(I) Principle of this application
  First, before describing a specific embodiment, the principle of the present application will be specifically described with reference to FIG. FIG. 1 is a waveform diagram showing an example of a focus error signal that is a subject of the present application, in which the horizontal axis is the distance l from the optimum condensing position and the vertical axis is the voltage value Vfe as the focus error signal Sfe.
[0019]
  In the present application, when spherical aberration occurs in the light beam, a correction parameter for correcting the spherical aberration by using a decrease in sensitivity described later in a focus error signal for focus servo corresponding to the generation amount. To get.
[0020]
  Here, the correction parameter refers to various known spherical aberration correction methods for correcting spherical aberration that occur when information is recorded or reproduced on the optical disc, when executing correction processing of each spherical aberration. Indicates the parameters used for each spherical aberration correction method. More specifically, the spherical aberration correction method includes, for example, a method using a liquid crystal element and a method using an optical element. Among these methods, a liquid crystal element including a plurality of concentric liquid crystal regions is used. When spherical aberration correction is performed using this, the spherical aberration is corrected by controlling the voltage applied to each liquid crystal region by the corresponding correction parameter.
[0021]
  Further, as shown in FIG. 1, the sensitivity is a parameter defined as a slope α at the zero cross point of the focus error signal Sfe. The sensitivity decreases as the spherical aberration contained in the light beam increases.
[0022]
  More specifically, the present invention detects a result of injecting a disturbance signal into the servo loop after the focus servo loop is closed (closed state) during a period in which information is not recorded or reproduced on the optical disc. A so-called residual error signal (residual error signal that will be included in the focus error signal as a result of injecting the disturbance signal) included in the focus error signal is detected, and this is used to optimally correct the spherical aberration. To get.
[0023]
(II)First embodiment
  Next, a first embodiment according to the present application based on the above-described principle will be described with reference to FIGS.
[0024]
  2 is a block diagram illustrating a schematic configuration of the aberration correction apparatus according to the first embodiment, FIG. 3 is a diagram illustrating a detailed configuration of the aberration correction apparatus, and FIGS. 4 and 5 illustrate the aberration correction. FIG. 6 is a flowchart illustrating an aberration correction operation in the apparatus, and FIG. 6 is a block diagram illustrating a configuration of a modification according to the first embodiment.
[0025]
  As shown in FIG. 2, the aberration correction apparatus S according to the first embodiment includes a spindle motor 1 loaded with an optical disk DK, a pickup 2 that emits a light beam B for recording / reproducing information, and sensitivity detection means. Parameter acquisition unit 3, focus control unit 4 as servo loop control unit and disturbance injection unit, disturbance signal generation unit 5, and spherical aberration correction unit 6 as parameter determination unit and correction unit. .
[0026]
  As an information recording / reproducing apparatus for recording / reproducing information with respect to the optical disc, in addition to the configuration shown in FIG. 2, a control unit (not shown) that performs tracking servo in the light beam B and a control (not shown) that controls the rotation of the spindle motor 1 are performed. A reproducing unit (not shown) that reproduces information recorded on the optical disc DK using a detection signal detected from the pickup 2, a recording unit that records information on the optical disc DK using the light beam B, or information recording thereof A control unit or the like for controlling the reproduction operation is included.
[0027]
  As shown in FIG. 3, the parameter acquisition unit 3 includes a multiplier 10 as a multiplication unit, an integration circuit 11 as an integration unit, and an absolute value circuit 12 as an absolute value conversion unit. .
[0028]
  Next, the operation will be described.
[0029]
  In the spherical aberration correction apparatus S according to the first embodiment, when acquiring the correction parameters prior to actual information recording / reproduction, first, the spherical aberration correction unit 6 is actually executed by the spherical aberration correction unit 6. A control signal Saj is output to perform spherical aberration correction using a preset initial value in a correction parameter used for spherical aberration correction processing.
[0030]
  In this state, the focus control unit 4 closes the focus servo loop and starts focus servo control. In parallel with this, the disturbance signal generation unit 5 outputs a disturbance signal Sg having a preset frequency and amplitude. Generate and output to the focus control unit 4 and the parameter acquisition unit 3. At this time, the optical disk DK is rotated by the spindle motor 1.
[0031]
  Here, the frequency of the disturbance signal Sg is outside the frequency band used for the focus servo, and the frequency of the detected focus error signal Sfe is equal to or higher than a preset value. Yes.
[0032]
  The focus servo control unit 4 generates a servo control signal Sfc so that the focus servo is executed while injecting the disturbance signal Sg into the focus servo loop, and outputs the servo control signal Sfc to the pickup 2. An objective lens (not shown) for focusing is driven in a direction perpendicular to the information recording surface of the optical disc DK. As a result, a focus error signal Sfe in which the disturbance signal Sg is injected is generated in the pickup 2.
[0033]
  Then, the focus error signal Sfe is fed back to the focus control unit 4 as it is, whereby an injection focus servo signal Sp corresponding to the focus servo loop injected by the disturbance signal Sg is generated and sent to the parameter acquisition unit 3. Is output. More specifically, as the injection focus servo signal Sp, the focus error signal Sfe in a state where the above-described disturbance is injected may be taken out from the focus servo loop as the injection focus servo signal Sp as it is, The servo control signal Sfc (servo control signal Sfc as a so-called drive signal) in a state where the disturbance is injected may be taken out from the focus servo loop as the injection focus servo signal Sp.
[0034]
  Next, as shown in FIG. 3A, the multiplier 10 in the parameter acquisition unit 3 multiplies the injection focus servo signal Sp and the disturbance signal Sg at that time to generate a multiplication signal Sm and integrate it. Output to the circuit 11.
[0035]
  Then, the integration circuit 11 integrates the multiplication signal Sm, generates an integration signal Sn, and outputs it to the absolute value circuit 12.
[0036]
  By the operations of the multiplier 10 and the integration circuit 11, the correlation between the injection focus servo signal Sp and the disturbance signal Sg at that time is detected.
[0037]
  Then, the absolute value circuit 12 detects the absolute value of the integral signal Sn and outputs it to the spherical aberration correction unit 6 as a sensitivity signal Sss indicating the sensitivity of the focus error signal Sfe at that time.
[0038]
  As a result, the spherical aberration correction unit 6 temporarily stores the value of the output sensitivity signal Sss, and sets the correction parameter value as a new value that is changed from the initial value by a preset change. The control signal Saj is output to the pickup 2 again.
[0039]
  By executing the above operation for correction parameters having a plurality of different types of values, the change in the value of the sensitivity signal Sss with respect to the change in the correction parameter can be acquired by the spherical aberration correction unit 6.
[0040]
  Here, as shown in FIG. 3B, the sensitivity signal Sss shows a characteristic that its value increases as the spherical aberration contained in the light beam B approaches zero. Therefore, the spherical aberration correction unit 6 performs an actual spherical aberration correction process in information recording / reproduction performed thereafter using a correction parameter having a value that maximizes the value of the sensitivity signal Sss.
[0041]
  Next, an embodiment of the present application in an actual information recording / reproducing process will be described with reference to FIGS.
[0042]
  First, an embodiment in the information reproduction process will be described with reference to FIG.
[0043]
  In the information reproducing process from the optical disk DK, when the optical disk DK is loaded in the information reproducing apparatus including the aberration correction apparatus S (step S1), preset initial adjustment such as the rotation speed adjustment is executed (step S1). S2) Next, the spindle servo loop is turned on to start the rotation of the spindle motor 1 (step S3).
[0044]
  Next, the focus servo loop is turned on by the focus controller 4 (step S4), and the injection of the disturbance signal Sg from the disturbance signal generator 5 is started (step S5).
[0045]
  Then, the sensitivity of the focus error signal Sfe is measured by the above-described operation to determine the correction parameter (step S6), the injection of the disturbance signal Sg is stopped (step S7), and other necessary adjustment operations are performed (step S6). S8).
[0046]
  Thereafter, information reproduction processing from the optical disk DK is started while the spherical aberration correction unit 6 corrects the spherical aberration using the determined correction parameter (step S9).
[0047]
  Next, an embodiment in the information recording process for the optical disc DK will be described with reference to FIG.
[0048]
  In the information recording process for the optical disk DK, when the optical disk DK is loaded in the information recording apparatus including the aberration correction apparatus S, an initial setting process or the like preset as the information recording apparatus (the light beam B at the time of information recording). Initial reproduction processing for intensity setting processing or the like is executed (step S10).
[0049]
  Next, injection of the disturbance signal Sg is started from the disturbance signal generator 5 while the focus servo loop in the initial reproduction process is closed (step S11).
[0050]
  Then, the sensitivity of the focus error signal Sfe is measured by the above-described operation to determine the correction parameter (step S12), the injection of the disturbance signal Sg is stopped (step S13), and then the determined correction parameter is used. Then, the information recording process for the optical disc DK is started while the spherical aberration correction unit 6 corrects the spherical aberration (step S14).
[0051]
  As described above, according to the operation of the aberration correction apparatus S according to the first embodiment, the sensitivity of the focus error signal Sfe obtained by changing the correction parameter while the focus servo loop is in the closed state is set. The correction parameter when the detected sensitivity is maximized is the correction parameter that is actually used for correcting the spherical aberration. Therefore, even if no information is recorded on the optical disk DK or the tracking servo Even in a state in which is not executed, necessary correction parameters can be acquired.
[0052]
  Further, since the processing is performed with the focus servo loop closed, for example, necessary correction parameters can be acquired while preventing the objective lens in the pickup 2 from colliding with the optical disk DK.
[0053]
  Furthermore, the necessary correction parameters can be acquired without making a large structural change to the conventional pickup or the like.
[0054]
  The correction parameter when the absolute value as the sensitivity obtained using the result of multiplying the injection focus servo signal Sp and the disturbance signal Sg while the focus servo loop is in the closed state becomes the maximum, Since it is used for correcting spherical aberration, a correction parameter having a value that can reliably correct spherical aberration can be generated.
[0055]
  Furthermore, since the frequency of the disturbance signal Sg is outside the frequency band used for the focus servo and the amplitude of the focus error signal Sfe is greater than or equal to a preset value, the disturbance signal Sg is in a closed state. Desired correction parameters can be obtained accurately without adversely affecting the function of the focus servo loop.
[0056]
  Further, since the spherical aberration is corrected using the correction parameter when the sensitivity of the focus error signal Sfe obtained by changing the correction parameter while the focus servo loop is in the closed state is maximized, the optical at that time is corrected. It is possible to reliably correct the spherical aberration by correcting the spherical aberration by using the correction parameter having the optimum value for the system without greatly changing the apparatus configuration.
[0057]
  In the above-described first embodiment, the case where the parameter acquisition unit 3 includes the multiplier 10, the integration circuit 11, and the absolute value circuit 12 as illustrated in FIG. In addition to this, the parameter acquisition unit 3 may include a band pass filter 15 as an extraction unit and an amplitude measurement circuit 16 as an amplitude measurement unit, like the parameter acquisition unit 3A shown in FIG.
[0058]
  As an operation of the parameter acquisition unit 3A in this case, first, the band pass filter 15 extracts a component having the same frequency component as the frequency of the disturbance signal Sg at that time from the injection focus servo signal Sp, and extracts the extracted signal Sbp. Is output to the amplitude measurement circuit 16.
[0059]
  As a result, the amplitude measurement circuit 16 measures the amplitude of the extracted signal Sbp, and outputs the amplitude measurement value to the spherical aberration correction unit 6 as a sensitivity signal Sss indicating the sensitivity of the focus error signal Sfe at that time.
[0060]
  The sensitivity signal Sss similar to that of the parameter acquisition unit 3 described above can also be generated by the configuration of the parameter acquisition unit 3A. That is, the correction parameter when the value of the sensitivity signal Sss as the sensitivity obtained by extracting the disturbance signal component from the focus error signal Sfe while the focus servo loop is in the closed state is the spherical surface. Since it is used for aberration correction, a correction parameter having a value that can reliably correct spherical aberration can be generated.
[0061]
(III)Second embodiment
  Next, 2nd Embodiment which is other embodiment which concerns on this application is described using FIG.7 and FIG.8. FIG. 7 is a diagram for explaining a correction parameter acquisition method according to the second embodiment, and FIG. 8 is a diagram illustrating a detailed configuration of the aberration correction apparatus according to the second embodiment.
[0062]
  The overall configuration of the aberration correction apparatus according to the second embodiment is the same as that of the aberration correction apparatus S according to the first embodiment (see FIG. 2). In the aberration correction apparatus according to the second embodiment, FIG. Since only the detailed configuration of the parameter acquisition unit 3 shown in FIG. 4 is changed, the description of the overall configuration of the aberration correction apparatus according to the second embodiment will be omitted.
[0063]
  In the first embodiment described above, the sensitivity signal Sss is generated by paying attention to each amplitude in the relationship between the injection focus servo signal Sp and the disturbance signal Sg. However, in the second embodiment described below, the injection focus is generated. Focusing on the phase difference between the servo signal Sp and the disturbance signal Sg, a sensitivity signal is generated.
[0064]
  Here, as shown in FIG. 7, the phase delay amount with respect to the disturbance signal Sg in the injection focus servo signal Sp when the disturbance signal Sg is injected while the focus servo loop is closed is sensitive to the focus error signal Sfe. It is known that when the sensitivity is small (indicated by symbol γ in FIG. 7), the sensitivity is higher than when it is large (indicated by symbol β in FIG. 7).
[0065]
  Therefore, in the aberration correction apparatus of the second embodiment, the phase delay amount with respect to the disturbance signal Sg in the injection focus servo signal Sp is regarded as the sensitivity signal Sss, and as shown in FIG. Using the correction parameter having a value that minimizes the value of the sensitivity signal Sss, spherical aberration correction is performed in the subsequent recording / reproduction of information.
[0066]
  That is, as shown in FIG. 8B, the phase comparator 20 as the phase comparison means in the parameter acquisition unit 3B in the aberration correction apparatus according to the second embodiment has the phase of the injection focus servo signal Sp at that time. The phase of the disturbance signal Sg is compared, and the phase delay amount of the injection focus servo signal Sp with respect to the disturbance signal Sg is output to the spherical aberration correction unit 6 as a sensitivity signal Sss indicating the sensitivity of the focus error signal Sfe at that time. In the second embodiment, since the sensitivity of the focus error signal Sfe is detected from the magnitude relationship between the phase delay amounts for each correction parameter as described above, the frequency of the disturbance signal Sg at this time is the correction parameter. It is set in advance as a frequency at which the difference between the phase delay amounts detected when the sensitivity is changed (that is, when the sensitivity of the focus error signal Sfe is changed) is maximized.
[0067]
  Thereafter, as in the case of the first embodiment, the spherical aberration correction unit 6 temporarily stores the value of the output sensitivity signal Sss and changes the value of the correction parameter from the initial value to a preset change. The control signal Saj is output to the pickup 2 again as a new value changed by the amount.
[0068]
  Then, by executing this operation for correction parameters having different types of values, the change in the sensitivity signal Sss (phase delay amount) with respect to the change in the correction parameter can be acquired in the spherical aberration correction unit 6.
[0069]
  Here, since the value of the sensitivity signal Sss shows a characteristic that the spherical aberration included in the light beam B becomes closer to zero as described above (see FIG. 8A), the spherical aberration correction unit 6 Using the correction parameter having a value that minimizes the value of the sensitivity signal Sss, spherical aberration correction is performed in information recording / reproduction performed thereafter.
[0070]
  As described above, even when the aberration correction apparatus according to the second embodiment operates, as in the case of the first embodiment, even when no information is recorded on the optical disk DK, or tracking servo is executed. Even if it is not, necessary correction parameters can be acquired.
[0071]
  Further, since the processing is performed with the focus servo loop closed, for example, necessary correction parameters can be acquired while preventing the objective lens in the pickup 2 from colliding with the optical disk DK.
[0072]
  Furthermore, the necessary correction parameters can be acquired without making a large structural change to the conventional pickup or the like.
[0073]
  Further, the phase delay amount with respect to the phase of the disturbance signal Sg in the phase of the injection focus servo signal Sp while the focus servo loop is in the closed state is defined as sensitivity, and the correction parameter when the phase delay amount is minimized is spherical. Since it is used for aberration correction, a correction parameter having a value that can reliably correct spherical aberration can be generated.
[0074]
  In each of the above-described embodiments, the description has been given of the case where the correction parameter is obtained by the method according to the present application before executing the recording or reproduction of information with respect to the optical disc DK. Can also be performed in parallel with recording or reproduction of the information on the optical disc DK. In this case, since the correction parameter calculation method according to the present application is executed in parallel with recording or reproduction of actual information, the frequency of the disturbance signal Sg injected into the focus servo loop is used for the focus servo. The frequency needs to be outside the frequency band, and the amplitude of the disturbance signal Sg needs to be in a range that does not affect the recording or reproduction of the information.
[0075]
  Further, a program corresponding to the focus servo control process (particularly, the steps S4 to S7 in the flowchart shown in FIG. 4 or the steps S11 to s3 in the flowchart shown in FIG. 5) as the focus servo control unit 4 described above is flexible. The information is recorded on an information recording medium such as a disk or a hard disk, or acquired and recorded via the Internet, and the computer is read and executed by a general-purpose computer, so that the computer can be focused on each embodiment. It can also be used as the servo control unit 4.
[0075]
  Furthermore, it is needless to say that a CD (Compact Disc) or a DVD (Digital Versatile Disc) currently available can be used as the optical disc DK according to each embodiment described above. If an objective lens having a high numerical aperture is used for a blue-violet laser optical disc used for recording / reproducing information, the thickness of the protective layer on which the light beam is incident upon recording / reproducing information is thinner than that of the CD or DVD. The point that the optical disk can be protected when the correction parameter is acquired (this is because the objective lens does not collide with the optical disk because the focus servo loop is closed when the correction parameter is acquired). And has a particularly remarkable effect.
[Brief description of the drawings]
[0077]
FIG. 1 is a diagram illustrating the principle of the present invention.
FIG. 2 is a block diagram showing a schematic configuration of the aberration correction apparatus according to the first embodiment.
3A and 3B are diagrams illustrating a detailed configuration and the like of the aberration correction apparatus according to the first embodiment, FIG. 3A is a block diagram illustrating the detailed configuration, and FIG. 3B is a spherical aberration and sensitivity in the aberration correction apparatus. It is a graph which shows the relationship of a signal.
FIG. 4 is a flowchart (I) illustrating a timing at which an aberration correction process according to the first embodiment is executed.
FIG. 5 is a flowchart (II) illustrating a timing at which the aberration correction process according to the first embodiment is executed.
FIG. 6 is a block diagram showing a modification of the detailed configuration of the aberration correction apparatus according to the first embodiment.
FIG. 7 is a graph showing the relationship between the sensitivity of the focus error signal and the amount of phase delay in the aberration correction apparatus according to the second embodiment.
FIG. 8 is a diagram illustrating a detailed configuration of an aberration correction apparatus according to a second embodiment, and FIG. 8A is a graph illustrating a relationship between spherical aberration and a sensitivity signal in the aberration correction apparatus. (B) is a block diagram showing the detailed configuration.
[Explanation of symbols]
[0078]
  1 Spindle motor
  2 Pickup
  3, 3A, 3B Parameter acquisition unit
  4 Focus control unit
  5 Disturbance signal generator
  6 Spherical aberration corrector
  10 multiplier
  11 Integration circuit
  12 Absolute value circuit
  15 Bandpass filter
  16 Amplitude measurement circuit
  20 Phase comparator
  S aberration correction device

Claims (6)

In a correction parameter generation device that generates a correction parameter used to correct spherical aberration that occurs when performing at least one of recording and reproduction of information using a light beam with respect to a recording medium,
Servo loop control means for closing a focus servo loop for performing focus servo on the light beam condensing position;
While the focus servo loop is in the closed state, a disturbance signal having a preset frequency and amplitude is electrically injected into the focus servo loop, and the focus servo is electrically injected with the disturbance signal. Disturbance injection means for extracting any electrical signal in the loop as a disturbance injection signal;
Sensitivity detection means for detecting the sensitivity of the focus error signal obtained by changing the correction parameter while the focus servo loop is in a closed state, corresponding to the changed correction parameter;
A parameter determining unit that sets the correction parameter when the sensitivity is maximized as the correction parameter that is actually used for correcting the spherical aberration;
With
The frequency of the disturbance signal is outside the frequency band used for the focus servo, and the amplitude of the focus error signal is equal to or higher than a preset value ,
The sensitivity detection means compares the phase of the disturbance injection signal obtained while the focus servo loop is in a closed state with the phase of the disturbance signal, and a phase delay amount of the disturbance injection signal with respect to the disturbance signal Phase comparison means for outputting as the sensitivity,
The correction parameter generation device characterized in that the parameter determination means uses the correction parameter when the phase delay amount is minimized as the correction parameter actually used for correcting the spherical aberration . A correction parameter generating device according to claim 1 ;
Correction means for correcting the spherical aberration using the correction parameter determined by the parameter determination means;
An aberration correction apparatus comprising: In a correction parameter generation method for generating a correction parameter used for correcting spherical aberration generated when at least one of recording and reproduction of information using a light beam with respect to a recording medium is performed.
A servo loop control step of closing a focus servo loop for performing focus servo on the light beam condensing position;
While the focus servo loop is in the closed state, a disturbance signal having a preset frequency and amplitude is electrically injected into the focus servo loop, and the focus servo is electrically injected with the disturbance signal. A disturbance injection step of extracting any electrical signal in the loop as a disturbance injection signal;
A sensitivity detection step of detecting the sensitivity of the focus error signal obtained by changing the correction parameter while the focus servo loop is in a closed state, corresponding to the changed correction parameter;
A parameter determining step in which the correction parameter when the sensitivity is maximized is the correction parameter actually used for correcting the spherical aberration;
Including
The frequency of the disturbance signal is outside the frequency band used for the focus servo, and the amplitude of the focus error signal is equal to or higher than a preset value,
The sensitivity detection step compares the phase of the disturbance injection signal obtained while the focus servo loop is in a closed state with the phase of the disturbance signal, and a phase delay amount of the disturbance injection signal with respect to the disturbance signal A phase comparison step of outputting as the sensitivity,
The parameter determination means uses the correction parameter when the phase delay amount is minimized as the correction parameter that is actually used for correcting the spherical aberration . A correction parameter generation method according to claim 3,
  A correction step of correcting the spherical aberration using the correction parameter determined in the parameter determination step;
  An aberration correction method comprising: A correction parameter generation computer included in a correction parameter generation device that generates a correction parameter used to correct spherical aberration generated when at least one of recording and reproduction of information using a light beam with respect to a recording medium is performed. ,
Servo loop control means for closing a focus servo loop for performing focus servo on the light beam condensing position;
While the focus servo loop is in the closed state, a disturbance signal having a preset frequency and amplitude is electrically injected into the focus servo loop, and the focus servo is electrically injected with the disturbance signal. Disturbance injection means for extracting any electrical signal in the loop as a disturbance injection signal;
Sensitivity detection means for detecting the sensitivity of the focus error signal obtained by changing the correction parameter while the focus servo loop is in the closed state, corresponding to the changed correction parameter, and
Parameter determining means that uses the correction parameter when the sensitivity is maximized as the correction parameter actually used for correcting the spherical aberration,
A correction parameter generation program that functions as
Furthermore, the frequency of the disturbance signal is outside the frequency band used for the focus servo, and the amplitude of the focus error signal is equal to or higher than a preset value,
The correction parameter generation computer that functions as the sensitivity detection means compares the phase of the disturbance injection signal obtained while the focus servo loop is closed with the phase of the disturbance signal, and the disturbance injection signal Functioning as phase comparison means for outputting the phase delay amount with respect to the disturbance signal as the sensitivity,
Further, the correction parameter generation computer that functions as the parameter determination means functions so that the correction parameter when the phase delay amount is minimized is the correction parameter that is actually used for correcting the spherical aberration. A correction parameter generation program characterized in that   An aberration correction program that causes a computer included in the aberration correction apparatus according to claim 2 to function as the correction unit.

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