JP2009140543A - Optical disk reproducing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an efficiency of obtaining an optimum set value of a spherical aberration to adjust the spherical aberration for an optical disk reproducing system that can reproduce an optical disk having a plurality of signal recording layers. <P>SOLUTION: The optical disk reproducing system records evaluation values from a plurality of layers when sweeping a focus actuator at a plurality of points. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disk reproducing apparatus suitable for signal reproduction from an optical disk having a plurality of signal recording layers.

  As background art of this technical field, for example, there is JP-A-2005-317052 (Patent Document 1). This publication describes that “it provides an optical information recording / reproducing apparatus capable of correcting and adjusting spherical aberration in a short time”.

JP 2005-317052 A

  Some optical disc apparatuses that read signals from a plurality of signal recording layers of an optical disc need to correct the spherical aberration of an optical pickup for reading in accordance with the position of the signal recording layer to be read. The position of the signal recording layer varies. Therefore, it is necessary to adjust the spherical aberration for each optical disc, and the spherical aberration adjustment corresponding to the position of each signal recording layer is performed when the disc is mounted.

  For spherical aberration adjustment, a method of examining changes in the observation target signal such as tracking error signal and reproduction RF signal with focus servo applied, or an observation target such as focus error signal and total light amount signal without focus servo applied. There is a method of examining the change in signal, but both are adjustments that are performed by changing two types of setting values, spherical aberration setting value and focus offset setting value, in two dimensions, and in an optical disc having a plurality of signal recording layers Since adjustment is required for each signal recording layer, there is a problem that adjustment takes time.

  In Patent Document 1, no consideration is given to spherical aberration correction in an optical disc having a plurality of signal recording layers.

  The problem to be solved by the present invention is to improve the processing efficiency for obtaining the optimum value of the spherical aberration setting value in the spherical aberration adjustment processing in the optical disk reproducing apparatus that supports reproduction from an optical disk having a plurality of signal recording layers. .

  In order to solve the above-described problem, in the optical disc reproducing apparatus of the present invention, as an example, the evaluation values from the plurality of signal recording layers when the focus actuator is swept at a plurality of spherical aberration set points are recorded and recorded. Can be solved by calculating the optimum point of the spherical aberration setting value for each signal recording layer.

  According to the present invention, it is possible to improve the processing efficiency for obtaining the optimum value of the spherical aberration setting value in the spherical aberration adjustment processing in the optical disk reproducing apparatus that supports reproduction from an optical disk having a plurality of signal recording layers.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 4 is a block diagram showing the configuration of a portion related to the present embodiment in an optical disk reproducing apparatus that supports reproduction from an optical disk having a plurality of signal recording layers. Note that portions not directly related to the present embodiment are not described and description thereof is omitted. The configuration will be described below with reference to the drawings.

  A process for reproducing information recorded on the optical disc 10 will be described. First, the system controller 1 controls the spherical aberration correction control / drive circuit 2 to set the spherical aberration correction mechanism inside the optical pickup 12 to a predetermined setting. Next, the objective lens 11 is swept in the focus direction while a predetermined laser (not shown) is emitted, and the type of the optical disk is identified using a signal obtained at that time. At this time, the system controller 1 outputs a sweep signal from the focus actuator sweep control circuit 14 and controls the focus actuator drive signal switching circuit 16 to output the sweep signal. Then, the objective lens 11 is swept by the output signal of the focus actuator drive circuit 3. The signal output from the optical pickup 12 during the sweep is input to the focus error signal detection circuit 4 and the total light amount signal detection circuit 6, and the signal output from each circuit is a focus for measuring each signal. Input to the error signal measurement circuit 5 and the total light quantity signal measurement circuit 7 to perform necessary measurement processing. The results of these measurement processes are input to the system controller 1, stored in a memory built in the system controller 1, and disc discrimination processing is performed based on the stored measurement values to identify the disc type.

  Next, spherical aberration adjustment performed after disc identification will be described.

  When the disc type is identified and it is found that the optical disc is an optical disc having two or more signal recording layers, it is necessary to adjust the spherical aberration at an appropriate stage thereafter.

  The reason will be described below.

  Among optical disks, DVD, Blu-ray, HD DVD, and the like have two or more signal recording layers. In these multilayer optical discs, it may be necessary to correct the spherical aberration of the optical pickup when reproducing information from the target signal recording layer. Spherical aberration varies depending on the distance from the laser light incident surface of the optical disk to the signal recording surface, the refractive index of the material, etc., and these vary widely between disk manufacturers and lots, so adjustment is required for each disk. There are many things. Therefore, in many cases, an optical disk reproducing apparatus having a spherical aberration correction function corresponding to a multilayer optical disk performs spherical aberration adjustment when the multilayer disk is mounted.

  An example of a conventional method for adjusting spherical aberration will be described.

  The spherical aberration adjustment described here is performed through two stages of coarse adjustment and fine adjustment.

  Coarse adjustment is performed with the focus servo applied to the signal recording layer to be adjusted. First, measure the tracking error signal amplitude for two variables, spherical aberration correction amount and focus servo offset amount, and search for a combination of spherical aberration correction amount and focus servo offset amount that maximizes the tracking error signal amplitude. Is the result of coarse adjustment. Next, using the coarse adjustment result as an initial value, the amplitude of the RF signal is measured for two variables of the spherical aberration correction amount and the focus servo offset amount, and the spherical aberration correction amount that maximizes the RF signal amplitude A combination of focus servo offset amounts is searched for and used as a result of fine adjustment. Then, the final spherical aberration adjustment result is obtained in consideration of the fine adjustment result and the coarse adjustment result.

  Note that the coarse adjustment is a coarse adjustment determined according to the servo signal or the total reflected light amount, and the fine adjustment is to actually reproduce the reproduction signal and evaluate the reproduction performance, or actually record it. It can also be said to be an adjustment for evaluating the recording quality.

  As described above, since the spherical aberration adjustment needs to be determined through a complicated processing process, the adjustment takes several tens of seconds, and the time required for starting the reproduction process for the disc after the optical disc is mounted can be reduced. It was a factor to prolong. For this reason, shortening of this time has been a major problem in the development of optical disc apparatuses.

  In recent years, the use of recording HD (High Definition) images on an optical disk is increasing, and therefore, it is desired to increase the storage capacity of recording on one optical disk. Thus, a method has been announced for expanding the storage capacity of an optical disk by expanding the structure of the optical disk from a maximum of two layers to three or more.

  Even in the optical disk apparatus corresponding to these multilayer optical disks, it is necessary to adjust the spherical aberration suitable for each signal recording layer corresponding to the position of each signal recording layer. In this case, the spherical aberration adjustment time required when the multilayer disk is mounted becomes longer as the number of layers increases. As a result, the time from when the disc is loaded to when playback is started requires minutes, which impairs user convenience.

  Therefore, the present embodiment aims to realize a spherical aberration adjustment method capable of reducing the time required for spherical aberration correction in a multi-layer disc, and more specifically, by improving the processing corresponding to the above-described coarse adjustment. Realize. Hereinafter, the spherical aberration adjusting method according to the present embodiment will be described.

  Figure 1 shows the case where a multilayer optical disc having three signal recording layers is mounted on an optical disc reproducing apparatus capable of adjusting spherical aberration, and the spherical aberration setting is set to be optimal in layer 3, and the spherical aberration setting is set in layer 1. It is a schematic diagram showing a focus error signal and a total light quantity signal when the objective lens is swept from a state far from the optical disk surface to a near state in two cases where it is set to be optimum. In the following description, for the sake of simplicity, it is assumed that the reflectance of each layer is the same, but the object of implementation of this embodiment is not limited to this.

  First, the case where the spherical aberration setting is set to be optimum in the layer 3 will be described. In this case, the spherical aberration is most appropriately corrected in the layer 3, and the spherical aberration increases in the order of the layer 2 and the layer 1. If the spherical aberration is large, the shape of the light spot formed by the reflected light from the optical disk returning to the optical detector in the optical pickup is disturbed. As a result, the waveform of the focus error signal and the total light quantity signal is destroyed, and the amplitude is reduced. Affected by. Therefore, when the magnitudes of these signals are compared for each layer, the layer 3 is the largest, and the layers 2 and 1 become smaller in this order.

  Next, a case where the spherical aberration setting is set so as to be optimal in the layer 1 will be described. In this case, the spherical aberration is most appropriately corrected in the layer 1, and the spherical aberration increases in the order of the layer 2 and the layer 3. As a result, for the same reason as described above, when the magnitudes of the focus error signal and the total light amount signal are compared for each layer, the layer 1 is the largest, and the layers 2 and 3 are sequentially smaller.

  The above description will be explained using equations.

  The amplitude of the focus error signal is represented by a function F, and the magnitude of the total light amount signal is represented by a function P. In both functions F and P, the number of the layer with the best spherical aberration adjustment is the first variable, and the number of the layer that observes the signal is the second variable. Therefore, for example, when the spherical aberration setting is set to be optimal in layer 3, the amplitude of the focus error signal of layer 1 is F (L3, L1).

In this way, the relationship between the magnitudes of signals (●) can be expressed as shown in FIG.
F (L3, L3)> F (L3, L2)> F (L3, L1)
P (L3, L3)> P (L3, L2)> P (L3, L1)
F (L1, L1)> F (L1, L2)> F (L1, L3)
P (L1, L1)> P (L1, L2)> P (L1, L3)
Can be expressed as

Next, FIG. 2 shows the above relationship with the function F and the function P with the spherical aberration adjustment position as the horizontal axis. FIG. 2 shows the following relationship.
F (L1, L1)> F (L2, L1)> F (L3, L1)
P (L1, L1)> P (L2, L1)> P (L3, L1)
F (L3, L3)> F (L2, L3)> F (L1, L3)
P (L3, L3)> P (L2, L3)> P (L1, L3)
The curve connecting the points in Fig. 2 shows how the magnitude of the signal obtained from layer 1 or layer 3 changes depending on the spherical aberration setting, and the maximum value of this curve is observed in the target layer. This is the spherical aberration set point at which the focus error signal or the total light quantity signal is maximized.

  This spherical aberration set point, which is the maximum value, is generally different from the coarse adjustment result of the spherical aberration described above, but is the point where the amplitude F of the focus error signal or the magnitude P of the total light quantity signal is maximized. Thus, it can be regarded as an adjustment target point for spherical aberration adjustment corresponding to the coarse adjustment result.

  Therefore, if the maximum value of the curve in FIG. 2 in each signal recording layer can be obtained, an adjustment target point for spherical aberration adjustment corresponding to the coarse adjustment result can be obtained.

  Therefore, here, the following steps are performed to obtain the maximum value of the curve in FIG. 2 in each signal recording layer, and the adjustment target point is obtained therefrom.

  FIG. 3 is a schematic diagram showing an example of a method for obtaining an adjustment target point for spherical aberration adjustment from the amplitude F of the focus error signal and the magnitude P of the total light quantity signal at a plurality of spherical aberration setting values in this embodiment. .

  Step 1: Spherical aberration setting values are set from S1 to S10 as shown in FIG.

  Step 2: The focus error signal amplitude F and the total light quantity signal size P in each layer at these spherical aberration setting values are measured to obtain a measurement point (◯), and the value is stored in the memory built in the system controller 1 Remember.

  Step 3: From these measurement points stored in the memory, the maximum values of the respective curves with respect to the spherical aberration setting values of the focus error signal and the total light quantity signal obtained from each signal recording layer are obtained by numerical calculation such as polynomial approximation.

  Step 4: The maximum value obtained for each signal recording layer is set as a candidate for an adjustment target point for spherical aberration adjustment.

  Step 5: From the plurality of adjustment target point candidates, an adjustment target point is obtained by an appropriate method such as averaging or weighted averaging.

  Here, S1 to S10 are roughly arranged with spherical aberration setting values at equal intervals. However, the arrangement is not limited to this, and is arranged so that an appropriate value can be obtained in a numerical calculation when obtaining a local maximum value such as polynomial approximation. For example, various arrangement methods such as fine arrangement of spherical aberration setting values between L1 and L3 and the periphery thereof and rough arrangement or no arrangement at other positions can be employed. In addition, the spherical aberration setting value is roughly determined to determine the approximate maximum value position, and then the spherical aberration setting value around the maximum value is determined finely to determine the maximum value position accurately in two stages. A value may be obtained. In addition, although the number of set values is 10 here, the number is not limited to this, and may be appropriately increased or decreased so that the adjustment target point can be obtained with necessary accuracy. In addition, the number of set values is not fixed, but the number of set values may vary depending on the measurement situation.

  In addition, in the standard that the multi-layer disc should comply with, the allowable position range of each signal recording layer is often determined by the standard. For example, the spherical aberration setting value is set to the position where each signal recording layer is arranged. Spherical aberration setting values are arranged in such a way that they are arranged closely in the vicinity, arranged in the middle of the position where each signal recording layer can be arranged, arranged in the middle of the signal recording layer and the adjacent signal recording layer, etc. Also good.

  In this embodiment, the focus error signal amplitude and the total light quantity signal magnitude are measured to derive the adjustment target point for spherical aberration adjustment, so the maximum points derived from these signals match. There are things that do not. This phenomenon often occurs due to the signal detection characteristics of the optical pickup. The specific reasons are as follows: (1) Since the amplitude of the focus error signal is generally smaller than the magnitude of the total light quantity signal, the amplitude of the focus error signal is a maximum value when the spherical aberration setting interval is wide. (2) Since the total light quantity signal is easily affected by disturbances such as stray light, the spherical aberration setting value that takes the maximum value is shifted due to the influence of disturbance such as stray light. It is easy.

  In such a case, depending on the situation, (1) a weighted average of the midpoint or two local maximum points of the two local maximum points determined by the focus error signal amplitude and the total light quantity signal size, respectively. Use points. (2) Perform measurement a plurality of times and use the average value of the maximum values obtained. (3) Perform two measurements, and at that time, without changing the spherical aberration setting interval, the start position is shifted by 1/2 of the interval in the first and second measurements, and both measured values are By using it to calculate the maximum value, the effective spherical aberration setting interval is halved. (4) It is possible to improve by using a technique such as using only the amplitude of the focus error signal when the total light amount signal exceeds a predetermined magnitude for derivation.

  In this embodiment, the process for disc identification and the process for obtaining the adjustment target point for spherical aberration adjustment corresponding to the coarse adjustment can be performed simultaneously. In the disc identification processing, the spherical aberration is set to a predetermined value, and the focus actuator is swept while the predetermined laser is emitted, and the focus error signal, total light amount signal, tracking error output from the optical pickup during this time This is a process for identifying the disc type from a signal such as a signal. On the other hand, the process for obtaining the adjustment target point of the spherical aberration adjustment of the present invention described above stores the measurement results of the focus error signal, the total light amount signal, the tracking error signal, etc. in the memory, and the polynomial stored in the value stored in the memory Is a process for obtaining an adjustment target point for spherical aberration adjustment by performing the above numerical calculation process. Both of them have many similarities in the signal to be referred to and the sweep processing for obtaining it, and the processing can be made common. If the processing is standardized, a further effect that the total time of the disc identification processing and the spherical aberration adjustment processing can be shortened is produced.

  Next, a second embodiment of the present invention will be described.

  FIG. 6 is a block diagram showing the configuration of a part related to the present embodiment in an optical disc reproducing apparatus corresponding to reproduction from an optical disc having a plurality of signal recording layers, for explaining the second embodiment. Note that portions not directly related to the present embodiment are not described in the same manner as in the description of the first embodiment, and description thereof is omitted. The configuration will be described below with reference to the drawings.

  A process for reproducing information recorded on the optical disc 10 will be described. First, the system controller 1 controls the spherical aberration correction control / drive circuit 2 to set the spherical aberration correction mechanism inside the optical pickup 12 to a predetermined setting. Next, the objective lens 11 is swept in the focus direction with a predetermined laser (not shown) being emitted, and the type of the optical disk is identified using the signal obtained at that time. At this time, the system controller 1 controls the focus actuator sweep control circuit 14 to output a sweep signal and the focus actuator drive signal switching circuit 16 to output the sweep signal. Then, the objective lens 11 is swept by the output signal of the focus actuator drive circuit 3. The signal output from the optical pickup 12 during the sweep is input to the focus error signal detection circuit 4, the total light amount signal detection circuit 6, and the tracking error signal detection circuit 8. The signals output from the respective circuits are The signals are input to the focus error signal measurement circuit 5, the total light amount signal measurement circuit 7, and the tracking error signal measurement circuit 9 for measuring signals, and necessary measurement processing is performed. The results of these measurement processes are input to the system controller 1, and the process is performed to identify the disc type.

  Next, spherical aberration adjustment performed after disc identification will be described.

  Fig. 5 shows a case where a multilayer optical disc having three signal recording layers is mounted on an optical disc reproducing apparatus capable of adjusting spherical aberration, and the spherical aberration setting is set to be optimal in layer 3, and the spherical aberration setting is set in layer 1. It is a schematic diagram showing a tracking error signal and a total light amount signal when the objective lens is swept from a state far from the optical disk surface to a near state in two cases where it is set to be optimum. In the following description, for the sake of simplicity, it is assumed that the reflectance of each layer is the same, but the object of implementation of this embodiment is not limited to this.

  The difference between the present embodiment and the first embodiment is a signal that is measured when deriving the adjustment target point for spherical aberration adjustment, and the first embodiment is a focus error signal and a total light amount signal. In this embodiment, there are a tracking error signal and a total light amount signal, and there is a difference between the focus error signal and the tracking error signal. The influence and the effect which arise by this are demonstrated.

  The tracking error signal is output when the light spot is focused on the signal recording surface and the light spot crosses the track in that state. Therefore, in this embodiment, the optical disk is rotated so that the optical spot surely crosses the track by the eccentricity of the disk itself, or the objective lens is vibrated in the tracking direction so that the optical spot surely crosses the track. It is desirable to make it.

  In addition, the focus range in which the tracking error signal is normally output is a range in which the signal recording surface is focused, and thus is generally narrower than the focus S-character detection range. In addition, the interference component reflected from the signal recording layer that is not in focus and incident on the photodetector is superimposed as an offset on the tracking error signal from the signal recording layer that is in focus. The amplitude level of the tracking error signal is hardly affected. For these reasons, it may be possible to perform measurement with less error when using the tracking error signal than when using the focus error signal.

  Therefore, in this embodiment, it is possible to derive the adjustment target point for spherical aberration adjustment with higher accuracy than in the first embodiment.

  As described above, in the first and second embodiments, focus sweep is performed with a plurality of spherical aberration correction setting values, and evaluation values (focus error signal, total light amount signal, tracking error signal, etc.) in each layer are stored. Thus, the time required for correcting the spherical aberration can be shortened.

It is a schematic diagram which shows the relationship between the focus error signal when sweeping an objective lens, and the focus actuator position of a total light quantity signal. It is a schematic diagram which shows the relationship between the focus error signal when sweeping an objective lens, and the spherical aberration adjustment position of a total light quantity signal. It is a schematic diagram showing a method for obtaining an adjustment target point for spherical aberration adjustment from the focus error signal amplitude F and the total light quantity signal magnitude P at a plurality of spherical aberration setting values of the present invention. 1 is a block diagram showing the configuration of relevant parts in an optical disk reproducing apparatus according to a first embodiment of the present invention. It is a schematic diagram which shows the relationship between the tracking error signal when sweeping an objective lens, and the spherical aberration adjustment position of a total light quantity signal. FIG. 6 shows a block diagram of a configuration of a related portion in an optical disk reproducing device according to a second embodiment of the present invention.

Explanation of symbols

1 ... System controller,
2. Spherical aberration correction control / drive circuit,
3. Focus actuator drive circuit,
4 Focus error signal detection circuit,
5. Focus error signal measurement circuit,
6 ... Total light amount signal detection circuit,
7: Total light quantity signal measuring circuit,
8: Tracking error signal detection circuit,
9: Tracking error signal measurement circuit,
10 ... Optical disc,
11 ... objective lens,
12 ... optical pickup,
13 ... Spherical aberration correction mechanism,
14 ... Focus actuator sweep control circuit,
15: Focus servo control circuit,
16 ... Focus actuator drive signal switching circuit

Claims (16)

An optical disc playback apparatus capable of mounting an optical disc having a plurality of signal recording layers,
An objective lens for condensing laser light on the optical disc;
An actuator for driving the objective lens;
A detector for detecting reflected light from the optical disc;
Servo error signal generation means for generating a servo error signal based on the output from the detector;
A memory for storing a servo error signal generated by the servo error signal generating means;
Spherical aberration correction means for correcting spherical aberration;
A system controller;
Have
The system controller controls to store in a memory servo error signals obtained from a plurality of signal recording layers when the actuator sweeps the objective lens;
The system controller controls to derive a spherical aberration correction amount from a servo error signal stored in the memory;
Optical disk playback device. An optical disc playback apparatus capable of mounting an optical disc having a plurality of signal recording layers,
An objective lens for condensing laser light on the optical disc;
An actuator for driving the objective lens;
A detector for detecting reflected light from the optical disc;
A total light amount signal generating means for generating a total light amount signal by an output from the detector;
A memory for storing a total light amount signal generated by the total light amount signal generating means;
Spherical aberration correction means for correcting spherical aberration;
A system controller;
Have
The system controller controls to store a total light amount signal obtained from a plurality of signal recording layers in a memory when the actuator sweeps the objective lens,
The system controller controls to derive a spherical aberration correction amount from a total light amount signal stored in the memory;
Optical disk playback device. An optical disk reproducing apparatus according to claim 2, wherein
Servo error signal generation means for generating a servo error signal based on the output from the detector;
Have
The system controller controls to store a total light amount signal and a servo error signal obtained from a plurality of signal recording layers in a memory when the actuator sweeps the objective lens,
The system controller controls to derive a spherical aberration correction amount from a total light amount signal and a servo error signal stored in the memory;
Optical disk playback device. An optical disk reproducing apparatus according to any one of claims 1 to 3,
Reproduction signal evaluation means for evaluating the reproduction signal based on the output from the detector;
Have
The system controller further finely adjusts the derived spherical aberration correction amount based on the result from the reproduction signal evaluation means;
Optical disk playback device. Spherical aberration control mechanism driving means;
Spherical aberration setting means and focus error signal detection means;
A focus error signal measuring means;
Total light quantity signal detection means;
A total light quantity signal measuring means;
Tracking error signal detection means;
Tracking error signal measuring means;
Optical disc discrimination means;
In an optical disk reproducing device provided with at least a focus actuator driving means,
Discriminating the disc type by the optical disc discriminating means when the disc is loaded in the optical disc reproducing apparatus,
When it is determined that a multi-layer optical disc having a plurality of signal recording layers is mounted, the spherical aberration control mechanism driving means is operated according to an output from the spherical aberration setting control means to obtain a predetermined spherical aberration setting value,
Activating the focus actuator driving means to sweep the focus actuator and measuring the focus error signal detected by the focus error signal detecting means during the sweep operation by the focus error signal measuring means to obtain a focus error signal measurement result,
Further, the total light amount signal detected by the total light amount signal detecting means during the sweep operation is measured by the total light amount signal measuring means to obtain the total light amount signal measurement result,
Furthermore, the tracking error signal measured by the tracking error signal detecting means during the sweep operation is measured by the tracking error signal measuring means to obtain a tracking error signal measurement result,
Optimal spherical surface suitable for reading information from each signal recording layer of a plurality of signal recording layers of a multilayer optical disk mounted from the measured focus error signal measurement result, total light amount signal measurement result, and tracking error signal measurement result An optical disc reproducing apparatus, wherein an aberration correction set value is derived. Spherical aberration control mechanism driving means;
Spherical aberration setting means and focus error signal detection means;
A focus error signal measuring means;
Optical disc discrimination means;
In an optical disk reproducing device provided with at least a focus actuator driving means,
Discriminating the disc type by the optical disc discriminating means when the disc is loaded in the optical disc reproducing apparatus,
When it is determined that a multi-layer optical disc having a plurality of signal recording layers is mounted, the spherical aberration control mechanism driving means is operated according to an output from the spherical aberration setting control means to obtain a predetermined spherical aberration setting value,
Activating the focus actuator driving means to sweep the focus actuator and measuring the focus error signal detected by the focus error signal detecting means during the sweep operation by the focus error signal measuring means to obtain a focus error signal measurement result,
Deriving an optimal spherical aberration correction setting value suitable for reading information from each signal recording layer of the plurality of signal recording layers of the mounted multilayer optical disc from the measured focus error signal measurement result, Optical disk playback device. Spherical aberration control mechanism driving means;
Spherical aberration setting means and tracking error signal detection means,
Tracking error signal measuring means;
Optical disc discrimination means;
In an optical disk reproducing device provided with at least a focus actuator driving means,
Discriminating the disc type by the optical disc discriminating means when the disc is loaded in the optical disc reproducing apparatus,
When it is determined that a multi-layer optical disc having a plurality of signal recording layers is mounted, the spherical aberration control mechanism driving means is operated according to an output from the spherical aberration setting control means to obtain a predetermined spherical aberration setting value,
Activating the focus actuator driving means to sweep the focus actuator and measuring the tracking error signal detected by the tracking error signal detecting means during the sweep operation by the tracking error signal measuring means to obtain a tracking error signal measurement result,
Deriving an optimal spherical aberration correction setting value suitable for reading information from each signal recording layer of the plurality of signal recording layers of the mounted multilayer optical disk from the measured tracking error signal measurement result, Optical disk playback device. Spherical aberration control mechanism driving means;
Spherical aberration setting means and total light quantity signal detection means;
A total light quantity signal measuring means;
Optical disc discrimination means;
In an optical disk reproducing device provided with at least a focus actuator driving means,
Discriminating the disc type by the optical disc discriminating means when the disc is loaded in the optical disc reproducing apparatus,
When it is determined that a multi-layer optical disc having a plurality of signal recording layers is mounted, the spherical aberration control mechanism driving means is operated according to an output from the spherical aberration setting control means to obtain a predetermined spherical aberration setting value,
Activating the focus actuator driving means to sweep the focus actuator and measuring the total light quantity signal detected by the total light quantity signal detecting means during the sweep operation to obtain a total light quantity signal measurement result,
An optical disc characterized by deriving an optimal spherical aberration correction setting value suitable for reading information from each signal recording layer of a plurality of signal recording layers of a multi-layer optical disc mounted from the measured total light quantity signal measurement result Playback device. 9. The optical disk reproducing apparatus according to claim 5, wherein fine adjustment of spherical aberration correction setting is performed using the optimum spherical aberration correction setting value as an initial value. 9. The optical disk reproducing apparatus according to claim 5, wherein the optimum spherical aberration correction setting value is used when information is read from each signal recording layer. 11. The optical disk reproducing apparatus according to claim 5, wherein the optimum spherical aberration correction setting value is a focus error signal measurement result, a tracking error signal measurement result, or a total light amount signal measurement result measured at a plurality of different spherical aberration setting values. An optical disc reproducing apparatus derived from any one of the above. 12. The optical disk reproducing apparatus according to claim 11, wherein at least two spherical aberration setting values among the spherical aberration setting values used for deriving the optimum spherical aberration correction setting value are different from the spherical aberration setting values that can be set by the spherical aberration setting means. An optical disk reproducing apparatus characterized by being in the vicinity of both ends. 12. The optical disk reproducing apparatus according to claim 11, wherein at least two spherical aberration setting values among a plurality of different spherical aberration setting values used for deriving the optimum spherical aberration correction setting value are in the vicinity of both ends having different standard values to which the optical disk conforms. An optical disc playback apparatus characterized by the above. 12. The optical disk reproducing apparatus according to claim 11, wherein the number of spherical aberration setting values used for deriving the optimum spherical aberration correction setting value is larger than the number of signal recording layers of the mounted optical disk. 12. The optical disk reproducing apparatus according to claim 11, wherein the spherical aberration setting value used for deriving the optimal spherical aberration correction setting value includes at least a setting value corresponding to a position between each of the signal recording layers of the mounted optical disk. An optical disc reproducing apparatus characterized by the above. 12. The optical disk reproducing apparatus according to claim 11, wherein the spherical aberration setting value used for deriving the optimum spherical aberration correction setting value is a setting value corresponding to a position between each of the signal recording layers of the mounted optical disk and signals at both ends. An optical disc reproducing apparatus comprising at least a set value corresponding to a position outside the recording layer.

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