JP3855274B2 - Optical disk playback device - Google Patents

Description

  The present invention relates to a tracking control technique for an optical disc playback apparatus.

  When the optical disk reproducing apparatus detects that an operation of reproducing an optical disk such as a CD or a DVD has been performed, the optical disk is irradiated with a light beam while performing a focus servo and a tracking servo, and a data track formed in a spiral shape is irradiated. Seek the desired data and reproduce the data. Various methods such as a three-beam method, a push-pull method, and a DPD method (phase difference method) are known as tracking servos used in an optical disk reproducing apparatus, and the DPD method is generally used in DVD drives and the like. ing.

  In an optical disk reproducing device and an optical disk recording device, the amplitude of the tracking error signal may vary due to variations in tracking error signal detection efficiency for each disk or changes with time. For example, when the detection efficiency is large, that is, the amplitude is large with respect to the amount of light, track skipping is detected even for small track deviations that do not affect the signal characteristics at all, so that reproduction often stops. was there. Also, when the detection efficiency is low, that is, the amplitude is small with respect to the amount of light, the amplitude value of the track deviation signal is small even if the track is largely deviated. Since it detects that a track jump has occurred, there has been a problem that a seek error occurs and data cannot be reproduced.

To deal with such problems, conventionally, the amplitude and offset of the tracking error signal that occurs when the tracking control is off when the device is started up are measured, and the correction values for each track are complemented and calculated using the measured values. There is a tracking control device that can correct the fluctuation of the disk and head, and the fluctuation of the control system due to the change with time since the value is learned (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 5-144052 (page 4-6, FIG. 1-7)

  When a conventional tracking control device detects a reproduction operation of data recorded on an optical disc and seeks this data, it counts the pulses of the tracking error signal while performing tracking servo as described above. However, when the objective lens of the optical pickup is shifted in the tracking direction (hereinafter referred to as “lens shift”), there is a problem that the seek operation may not be performed correctly. This is because a state as described below occurs.

  FIG. 6 is a diagram showing the light receiving state of the four-divided photodetector and the output waveform of the photodetector depending on the presence or absence of shift in the objective lens of the optical pickup. Note that the output waveform of the photodetector indicates a signal waveform output from each photodetection area when a plurality of tracks are traversed in the radial direction of the optical disc with the tracking servo turned off. As shown in FIG. 6, the quadrant photodetector 201 includes light detection areas 201 a to 201 d, and each area outputs a signal corresponding to the area and the amount of light irradiated as is well known. Further, as is well known, the optical pickup includes an objective lens for converging the light beam on the optical disc and a tracking servo mechanism for shifting the objective lens in a direction (radial direction) across the track. The reflected light from the optical disk is detected while moving the objective lens. Also, when tracking servo is performed using a quadrant photodetector, the phase difference tracking error signal corresponding to the phase difference between the diagonal sum signal (A + C) and (B + D) of the quadrant photodetector is checked. It is possible to grasp whether or not a tracking error has occurred.

As shown in FIGS. 6A and 6B, when the pit depth of the optical disk is λ / 4, the light receiving position of the light beam on the quadrant photodetector 201 is a normal position by lens shift. Even at the moved position, the phase difference between the diagonal sum signals (A + C) and (B + D) of the quadrant photodetector does not occur. On the other hand, if the optical disk is inaccurate or the wavelength of the laser beam is shifted and the pit depth of the optical disk is other than λ / 4, no lens shift occurs, as shown in FIG. As described above, there is no phase difference between the diagonal sum signals (A + C) and (B + D) of the quadrant photodetector. However, when the lens shifting occurs, as shown in FIG. 6 (D), 4 phase difference of the sum signal of the diagonal split photodetector (A + C) and (B + D) is generated. At this time, since the signal levels of the four-divided photodetector regions 201a to 201d are different, the amplitude of the tracking error signal changes. Furthermore, since the lens shift amount changes depending on the situation when the tracking servo is performed, the variation in the amplitude of the tracking error signal cannot be eliminated even if correction is performed as in the conventional tracking control device.

  Therefore, if the tracking error signal pulses are counted during the seek operation of the data recorded on the optical disk in such a situation, a count error occurs due to the effect of the lens shift, and the seek operation is repeated many times. Sometimes it could not be done correctly.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disk reproducing apparatus that can accurately perform a seek operation during reproduction of an optical disk without causing a miscounting of tracking error signals due to the influence of lens shift.

  The present invention has the following configuration as means for solving the above problems.

(1) an optical pickup that irradiates an optical disk with laser light through an objective lens;
Tracking servo means for shifting the objective lens in the radial direction of the optical disc;
Moving means for moving the optical pickup in the radial direction of the optical disc;
A tracking error signal generating means for generating a tracking error signal, and outputs the amplified based on the reflected light of the laser light irradiated on the optical disk,
In an optical disk playback device comprising:
When the apparatus is started up and when the optical disk is replaced, the optical pickup is moved by the moving means to the vicinity of the inner peripheral end and the outer peripheral end in the recording area of the optical disc, and the objective is moved to the tracking servo means at each position. When the optical pickup is irradiated with laser light while shifting the lens ,
The tracking servo means includes control means for setting the amplification factor of the tracking error signal generating means to a value capable of detecting a phase difference tracking error signal having a minimum amplitude value.

  Since the degree of modulation varies depending on the type and manufacturer of optical disks, the amplitude of the tracking error signal detected by the optical pickup when irradiated with laser light varies, but the tracking error signal has the smallest amplitude. It was found that the recording area of the optical disc was near the inner peripheral end or the outer peripheral end. In the present invention, the amplitude of the tracking error signal is detected in the vicinity of the end on the outer peripheral side in addition to the vicinity of the end on the outer peripheral side in the recording area of the optical disc, and both detected signals are compared, and the amplitude is small. Select the other signal. In other words, since the minimum value of the tracking error signal amplitude is selected, the tracking error signal is always detected when seeking the data recorded on the optical disk based on this signal and a preset setting value. Gain (amplification factor) is determined, and the phase difference tracking error signal is amplified with this gain. Therefore, when performing a seek operation during reproduction of the optical disc, it is possible to reproduce the target data without causing a count error of the tracking error signal. In this configuration, since the minimum amplitude value of the tracking error signal is obtained by shifting the objective lens at the time of starting the optical disk reproducing apparatus or replacing the optical disk, the gain is again obtained with respect to the optical disk before the optical disk is replaced. Therefore, it is not necessary to make the optical disk reproducing apparatus perform a useless operation, and the time until reproduction can be shortened.

(2) an optical pickup that irradiates the optical disk with laser light via an objective lens;
Tracking servo means for shifting the objective lens in the radial direction of the optical disc;
Moving means for moving the optical pickup in the radial direction of the optical disc;
A tracking error signal generating means for generating a tracking error signal, and outputs the amplified based on the reflected light of the laser light irradiated on the optical disk,
In an optical disk playback device comprising:
The optical pickup is moved by the moving means in the vicinity of the inner peripheral end and the outer peripheral end in the recording area of the optical disc, and the optical pickup is laser-shifted while shifting the objective lens to the tracking servo means at each position. When irradiated with light ,
The tracking servo means includes control means for setting the amplification factor of the tracking error signal generating means to a value capable of detecting a phase difference tracking error signal having a minimum amplitude value.

  In this configuration, the amplitude of the tracking error signal is detected in the vicinity of the end on the outer peripheral side in addition to the vicinity of the end on the outer peripheral side in the recording area of the optical disc, and both detected signals are compared, Select the smaller signal. In other words, since the minimum value of the tracking error signal amplitude is selected, the tracking error signal is always detected when seeking the data recorded on the optical disk based on this signal and a preset setting value. Gain (amplification factor) is determined, and the phase difference tracking error signal is amplified with this gain. Therefore, when performing a seek operation during reproduction of the optical disc, it is possible to reproduce the target data without causing a count error of the tracking error signal.

An optical pickup that irradiates the optical disc with laser light via an objective lens;
Tracking servo means for shifting the objective lens in the radial direction of the optical disc;
Moving means for moving the optical pickup in the radial direction of the optical disc;
A tracking error signal generating means for generating a tracking error signal, and outputs the amplified based on the reflected light of the laser light irradiated on the optical disk,
In an optical disk playback device comprising:
A tracking error signal generated by the tracking error signal generating means by irradiating the optical disk with laser light while moving the optical pickup from the inner peripheral end to the outer peripheral end of the recording area of the optical disc by the moving means. and the detecting amplitude becomes smallest position, the while shifting the objective lens obtained when the laser beam, before Quito racking minimum amplitude value of the error signal to the tracking servo means in this position However, the tracking servo means includes control means for setting an amplification factor of the tracking error signal generating means so that a phase difference tracking error signal having a minimum amplitude value can be detected .

In this configuration, the end portion of the inner peripheral side of definitive to the recording area of the optical disc to the end portion of the outer peripheral side by moving the optical pickup, the amplitude of the tracking error signal is extracted minimum value, the influence of the further lens shift Considering this, the gain of the tracking error signal generation means is set, so even if the tracking error signal varies due to variations in the characteristics of the optical disk, the data can be reliably sought without missing the tracking error signal count. Desired data can be reproduced.

  According to the present invention, it is possible to accurately perform a seek operation without causing a count error due to the influence of a shift of an objective lens provided in an optical pickup during data seek of an optical disc.

  FIG. 1 is a block diagram of an optical disc playback apparatus according to an embodiment of the present invention. FIG. 2 is a configuration diagram of the photodetector. The optical disk reproducing apparatus 1 includes an optical pickup 2, an RF amplifier 3, a reproduction processing circuit 4, a servo circuit 5, a driver 6, a feed motor 7, a spindle motor 8, an operation unit 9, a display unit 10, and a system controller 11. .

  The optical pickup 2 includes a laser diode, a collimator lens, a beam splitter, an objective lens 100, and a photodetector 101, which are not shown, and irradiates the optical disk D with a laser beam from a radar diode, and reflects the reflected light from the optical disk D. The signal recorded on the optical disc D is optically read by converting it into an electrical signal by the photodetector 101. The optical pickup 2 also has a focusing actuator that moves the focal point of the laser beam applied to the optical disc D in the optical axis direction, and a tracking actuator that moves the laser beam in the radial direction of the optical disc D. As shown in FIG. 2, the photodetector 101 has a light receiving area substantially equally divided into four, and output signals A, B, C, and D from the four light receiving areas 101 a to 101 d are supplied to the RF amplifier 3. Is done.

  The RF amplifier 3 amplifies the signal read by the optical pickup 2 and outputs the amplified signal to the reproduction processing circuit 4, and generates a focusing error signal, a tracking error signal, and the like and outputs them to the servo circuit 5. The tracking error signal is generated by the tracking error signal generation circuit 22. The tracking error signal generation circuit 22 calculates the sum of the output signals A and C in one diagonal region of the quadrant photodetector 101 and the sum of the output signals B and D in the other diagonal region, and these two sums. A signal indicating the phase difference between the signals (A + C) and (B + D) is generated as a tracking error signal TE, amplified with a set amplification factor, and output to the servo circuit 5.

  The reproduction processing circuit 4 reproduces information by performing demodulation processing, error detection, correction processing, and the like on the signal output from the RF amplifier 3. Further, the reproduction processing circuit 4 generates a signal indicating the rotation speed of the optical disc D from the signal output from the RF amplifier 3 and outputs the signal to the servo circuit 5.

  The servo circuit 5 sets the values of the focusing drive signal FD and tracking error signal to 0 (reference level) for setting the value of the focusing error signal FE to 0 (reference level) based on the focusing error signal and tracking error signal output from the RF amplifier 3. A tracking drive signal TD and a feed motor drive signal for generating (reference level) are generated. Further, the servo circuit 5 generates a spindle motor drive signal for setting the rotation speed of the optical disk D to a target value based on a signal indicating the rotation speed of the optical disk D output from the reproduction processing circuit 4.

  The driver 6 drives the focusing actuator, tracking actuator, feed motor 7 and spindle motor 8 in the optical pickup 2 based on the focusing drive signal FD, tracking drive signal TD, feed motor drive signal, and spindle motor drive signal. . The feed motor 7 is a motor for moving the optical pickup 2 in the radial direction of the optical disc D. The spindle motor 8 is a motor for rotating the optical disc D.

  In the optical disk reproducing apparatus 1, the focal point of the laser beam applied to the optical disk D follows the recording surface of the optical disk D by the optical pickup 2, the RF amplifier 3, the servo circuit 5, the driver 6, the feed motor 7, and the spindle motor 8. Focusing servo for controlling the optical disc D, tracking servo for controlling the focal point of the laser beam applied to the optical disc D to follow the track of the optical disc D, and spindle servo for controlling the rotational speed of the optical disc D to a specified value. Servo mechanism that performs is configured. The focusing error signal is generated by the astigmatism method, and the tracking error signal is generated by the one-beam phase difference method.

  The operation unit 9 is used by the user to input various commands to the optical disc playback apparatus 1. A command input by the user to the optical disc playback apparatus 1 is output to the system controller 11.

  The display unit 10 displays information indicating the operating state of the optical disc playback apparatus 1 and information related to data being played back.

  The system controller 11 is composed of, for example, a microcomputer, and controls each component of the optical disc playback apparatus 1 in accordance with a command input by the user to the optical disc playback apparatus 1.

  Next, the processing operation of the optical disc playback apparatus according to the embodiment of the present invention will be described. Before seeking data, the optical disc playback apparatus 1 turns on the focus servo, turns off the tracking servo, and shifts the objective lens 100 of the optical pickup 2 to the end of the movable range to the optical disc D while shifting the lens. The minimum value of the amplitude of the tracking error signal is measured by irradiating the laser beam. Subsequently, the amplification factor of the RF amplifier is set so that the minimum value of the amplitude of the tracking error signal becomes a preset set value. Then, the focus servo and tracking servo are turned on to perform data seek. In this way, even if a lens shift occurs during data seek and the amplitude of the tracking error signal becomes the minimum value, the tracking error signal can be counted reliably. Therefore, no count error occurs during data seek, so that target data can be detected in a short time.

  As described above, the position where the minimum value of the amplitude of the tracking error signal is measured is preferably near the end on the inner peripheral side in the recording area of the optical disc D. In the optical disk reproducing apparatus, the home position of the optical pickup is normally set near the inner peripheral end of the optical disk. Therefore, if the measurement is performed at the above position, the moving distance of the optical pickup can be shortened. Therefore, the above process can be completed in a short time.

  FIG. 3 is a graph showing changes in the amplitude of the tracking error signal. The inventor of the present application has confirmed the amplitude of the phase difference tracking error signal detected by the four-divided photodetector when irradiating the laser beam to read out the optical disc for a plurality of optical discs. As a result, the amplitude of the phase difference tracking error signal differs depending on the type of optical disk and the manufacturer, but the following results were obtained. That is, as shown in FIG. 3A, the amplitude value of the tracking error signal is small on the inner peripheral side and outer peripheral side of the recording area of the optical disc D, and becomes large in the middle of the recording area. As shown in 3 (B) and (C), the result that the optical disk D became the smallest on the inner peripheral side or the outer peripheral side was obtained. Therefore, it has been found that the phase difference tracking error signal has the smallest amplitude near the inner periphery or the outer periphery of the optical disc D.

Therefore, in the present invention, before seeking data on the optical disc D, the focus servo is turned on and the tracking servo is turned off, so that the vicinity of the outer peripheral end and the inner peripheral end in the recording area of the optical disc are turned on. A minimum value is extracted by measuring the amplitude of the phase difference tracking error signal in the vicinity. Also, the extracted minimum value signals are compared, the signal with the smaller amplitude is selected, and the phase difference tracking error signal is detected based on this signal and a preset set value. Determine the amplification factor of the phase difference tracking error signal. At the time of data seek, the focus servo and tracking servo are turned on, and the phase difference tracking error signal is amplified with this amplification factor. As a result, when performing a seek operation to reproduce the data recorded on the optical disc D, the target data can be reproduced promptly without causing a miscounting of the tracking error signal.

  When measuring the minimum value of the amplitude of the phase difference tracking error signal, the objective lens 100 is shifted in the optical pickup 2 in the outer peripheral side direction and the inner peripheral side direction of the optical disc D. Therefore, even if the amplitude of the tracking error signal varies depending on the lens shift direction due to the characteristics of the optical disc D or the state of the optical pickup, the amplitude value of the tracking error signal is measured in both directions in this way to ensure the minimum value. Can be detected, and the occurrence of a seek error can be prevented.

  Next, specific processing will be described. FIG. 4 is a flowchart for explaining the operation of the tracking control apparatus. FIG. 4 illustrates a case where the amplitude value of the tracking error signal is measured in the vicinity of the inner peripheral end of the optical disc D and in the vicinity of the outer peripheral end. As shown in FIG. 4, when the system controller 11 of the optical disc reproducing apparatus 1 detects that an instruction to reproduce the optical disc D is input from the operation unit 9, the focus servo is turned off with the tracking servo of the optical pickup 2 turned off. Is turned on (s1). Since the system controller 11 does not measure the amplitude of the tracking error signal on the outer peripheral side in the recording area of the optical disc D (s2), it outputs a control signal to the servo circuit 5, and the optical motor 2 is driven by the feed motor 7. The optical disc D is moved to the vicinity of the end on the inner peripheral side of the recording area (s3).

  Subsequently, the system controller 11 outputs a control signal to the servo circuit 5 in a state where the optical pickup 2 is stopped, starts the lens shift of the objective lens (s5), and extends the lens to both ends within the movable range. While shifting, the servo circuit 5 is caused to measure the amplitude value of the tracking error signal output from the tracking error signal generation circuit 22 (s6). At this time, the servo circuit 5 detects the minimum amplitude value TEin of the tracking error signal and stores this value in a register (not shown) (s7).

  Next, the measurement of the amplitude of the tracking error signal on the inner circumference side and the outer circumference side of the recording area of the optical disc D has not been completed (s8), and the amplitude measurement of the tracking error signal on the inner circumference side has been completed (s2). The system controller 11 outputs a control signal to the servo circuit 5 to move the optical pickup 2 to the vicinity of the end on the outer peripheral side of the recording area of the optical disc D (s4).

  Subsequently, the system controller 11 outputs a control signal to the servo circuit 5 in a state where the optical pickup 2 is stopped, starts the lens shift of the objective lens (s5), and both end portions within the movable range of the objective lens. Then, the servo circuit 5 is caused to measure the amplitude value of the tracking error signal output from the tracking error signal generation circuit 22 (s6). At this time, the servo circuit 5 detects the minimum amplitude value TEout of the tracking error signal and stores this value in a register (not shown) (s7).

  Subsequently, the system controller 11 completes the measurement of the amplitudes of the tracking error signals on the inner and outer peripheral sides of the recording area of the optical disc D (s8), and compares the amplitude values TEin and TEout to determine the smaller amplitude value. Is selected as the minimum amplitude value TEmin (s9). Then, the amplification factor of the tracking error signal is calculated and set in the servo circuit 5 so that the minimum amplitude value TEmin becomes a preset set value (s10).

  The system controller 11 turns on the focus servo and tracking servo, starts data seek (s11), detects data (s12), and reproduces the data (s13).

  With the above processing, even if the amplitude of the tracking error signal is the smallest value, it is amplified so that it can always be counted, so that data can be reproduced without causing a seek error.

  Note that it is preferable to set an appropriate value as a reference value for preventing a tracking error signal count error by conducting an experiment or the like in advance.

  Depending on the characteristics of the optical disc D, the amplitude value of the tracking error signal may vary. In such a case, it is preferable to measure the amplitude value of the tracking error signal at a plurality of points in the recording area of the optical disc D. However, as the number of measurement points is increased, the time required for seeking and reproducing the data on the optical disc is required, so about 3 or 4 points are appropriate. For example, in the recording area of the optical disc D, three points near the outer peripheral end, the middle point, and the inner peripheral end are suitable.

  Also, the minimum value of the tracking error signal can be detected by moving the optical pickup from the inner circumference side of the optical disc D to the outer circumference side in the radial direction of the optical disc D. This process will be described based on a flowchart. FIG. 5 is a flowchart for explaining the operation of the tracking control apparatus.

  As shown in FIG. 5, when the system controller 11 of the optical disc reproducing apparatus 1 detects that an instruction to reproduce the optical disc D is input from the operation unit 9, the tracking servo of the optical pickup 2 is turned off and the objective lens is centered. The focus servo is turned on with the position fixed (s21). Then, the system controller 11 outputs a control signal to the servo circuit 5, and the optical pickup 2 is moved to the inner peripheral end of the recording area of the optical disc D by the feed motor 7 (s22). Then, the system controller 11 measures the tracking error signal by irradiating the recording surface of the optical disc D with laser light while moving the optical pickup 2 to the end on the outer peripheral side of the optical disc D at a predetermined speed (s23). ). At this time, the servo circuit 5 measures the magnitude (amplitude) of the tracking error signal output from the optical pickup 2, detects the position where the amplitude of the tracking error signal is the minimum value, and stores it in a register outside the figure. (S24). If the value of the amplitude of the tracking error signal is smaller than the value stored in the register, the value of the register is updated. The servo circuit 5 counts the pulses of the tracking error signal, and if it is determined that the tracking error signal is the minimum value, the servo circuit 5 stores the number of pulses in a register (not shown) to determine the value of the tracking error signal. The number of pulses is updated each time the value becomes smaller.

  When the system controller 11 completes the confirmation of the amplitude value of the tracking error signal up to the outer peripheral side end of the recording area of the optical disc D (s25), the tracking error signal of the optical pickup 2 is minimized with reference to a register outside the figure. It is moved to the position that was the value (s26). Then, the system controller 11 outputs a control signal to the servo circuit 5 with the optical pickup 2 stopped, and shifts the lens to both ends within the movable range of the objective lens (s27), and generates a tracking error signal. The servo circuit 5 is caused to measure the amplitude value of the tracking error signal output from the circuit 22 (s28). At this time, the servo circuit 5 detects the minimum amplitude value TEmin of the tracking error signal, and stores this value in a register (not shown) (s29). Then, the gain (amplification factor) of the tracking error signal is calculated and set in the servo circuit 5 so that the selected minimum amplitude value TEmin becomes a preset setting value (s30).

  The system controller 11 turns on the focus servo and tracking servo, starts data seek (s31), detects data (s32), and reproduces the data (s33).

  As described above, when the tracking error signal is detected while moving the optical pickup in the radial direction of the optical disc D, the tracking error signal amplitude is set at three or four locations on the optical disc D, depending on the moving speed of the optical pickup. The detection time is almost the same as when measuring. Therefore, even when such a process is executed, the process until the data is sought and reproduced can be completed in a short time.

  The processing described above can be set to be performed every time the optical disc D is reproduced, but may be set to be performed when the optical disc reproducing apparatus 1 is started or when the optical disc D is replaced. Thus, it is not necessary to set the gain again for the optical disk before replacing the optical disk with another optical disk, and the optical disk reproducing apparatus does not need to be operated.

1 is a block diagram of an optical disc playback apparatus according to an embodiment of the present invention. It is a block diagram of a photodetector. It is a graph showing the change of the amplitude of a tracking error signal. It is a flowchart for demonstrating operation | movement of a tracking control apparatus. It is a flowchart for demonstrating operation | movement of a tracking control apparatus. It is a figure which shows the light reception state of the 4 division | segmentation photodetector by the presence or absence of the shift in the objective lens of an optical pick-up, and the output waveform of each photodetector.

Explanation of symbols

  1-optical disk reproducing device, 2-optical pickup, 3-RF amplifier, 4-reproduction processing circuit, 5-servo circuit, 6-driver, 7-feed motor, 8-spindle motor, 9-operation unit, 10-display unit 11-system controller, 22-tracking error signal generation circuit, 44-tracking drive signal generation circuit, 45-servo controller

Claims (3)

An optical pickup that irradiates the optical disc with laser light via an objective lens;
Tracking servo means for shifting the objective lens in the radial direction of the optical disc;
Moving means for moving the optical pickup in the radial direction of the optical disc;
A tracking error signal generating means for generating a tracking error signal, and outputs the amplified based on the reflected light of the laser light irradiated on the optical disk,
In an optical disk playback device comprising:
When the apparatus is started up and when the optical disk is replaced, the optical pickup is moved by the moving means to the vicinity of the inner peripheral end and the outer peripheral end in the recording area of the optical disc, and the objective is moved to the tracking servo means at each position. When the optical pickup is irradiated with laser light while shifting the lens ,
An optical disk reproducing apparatus comprising: control means for setting the amplification factor of the tracking error signal generating means to a value by which the tracking servo means can detect a phase difference tracking error signal having a minimum amplitude value. An optical pickup that irradiates the optical disc with laser light via an objective lens;
Tracking servo means for shifting the objective lens in the radial direction of the optical disc;
Moving means for moving the optical pickup in the radial direction of the optical disc;
A tracking error signal generating means for generating a tracking error signal, and outputs the amplified based on the reflected light of the laser light irradiated on the optical disk,
In an optical disk playback device comprising:
The optical pickup is moved by the moving means in the vicinity of the inner peripheral end and the outer peripheral end in the recording area of the optical disc, and the optical pickup is laser-shifted while shifting the objective lens to the tracking servo means at each position. When irradiated with light ,
An optical disk reproducing apparatus comprising: control means for setting the amplification factor of the tracking error signal generating means to a value by which the tracking servo means can detect a phase difference tracking error signal having a minimum amplitude value. An optical pickup that irradiates the optical disc with laser light via an objective lens;
Tracking servo means for shifting the objective lens in the radial direction of the optical disc;
Moving means for moving the optical pickup in the radial direction of the optical disc;
A tracking error signal generating means for generating a tracking error signal, and outputs the amplified based on the reflected light of the laser light irradiated on the optical disk,
In an optical disk playback device comprising:
A tracking error signal generated by the tracking error signal generating means by irradiating the optical disk with laser light while moving the optical pickup from the inner peripheral end to the outer peripheral end of the recording area of the optical disc by the moving means. and the detecting amplitude becomes smallest position, the while shifting the objective lens obtained when the laser beam, before Quito racking minimum amplitude value of the error signal to the tracking servo means in this position However, the optical disc comprises control means for setting an amplification factor of the tracking error signal generating means so that the tracking servo means can detect a phase difference tracking error signal having a minimum amplitude value. Playback device.

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