JP4823032B2 - Error signal amplitude measuring method and optical disk reproducing apparatus - Google Patents

Description

  The present invention relates to an optical disk reproducing apparatus for reproducing an optical disk, and more particularly to an error signal amplitude measuring method and an optical disk reproducing apparatus for measuring the amplitude of an error signal output through a filter unit that passes a signal having a specific frequency or less from an optical pickup.

  In an optical disc playback apparatus such as a CD player, improving the playback capability of the optical disc is important for differentiation from other companies. In recent years, due to the widespread use of bad discs in the market and the wide variation in pickup characteristics, the amplitude of the error signal input from the pickup of the optical disc to be reproduced has become larger than before. Yes. Here, the error signal refers to a tracking error signal and a focus error signal. Therefore, for example, measures have been taken so that the reproduction capability of the disc does not deteriorate due to variations in the amplitude of the error signal, such as automatically adjusting the amplitude of the error signal from the optical disc to be reproduced to be constant.

  Here, an example of amplitude adjustment of an error signal that has been conventionally performed will be described.

  FIG. 8 is a block diagram showing a configuration of a conventional optical disc apparatus. In FIG. 8, the optical disk apparatus includes a spindle motor 52 that rotates an optical disk 51, a pickup 53 that reads a signal from the optical disk 51, a servo control LSI 54 that performs servo control, and a signal from the pickup 53 that is built in the servo control LSI 54. RF block 55, an external LPF 56 (low pass filter: hereinafter referred to as LPF) which is mounted outside the servo control LSI 54 and removes high frequency components of the signal from the RF block 55, and RF. A servo filter 57 that performs servo control operations based on an error signal from the block 55, a driver 58 that amplifies the signal from the servo filter 57 and drives the pickup 53 to the target point of the optical disc 51, and a control marker that controls these drivers It is comprised from the icon 59.

FIG. 9 is a block diagram showing the configuration of the error signal amplitude adjustment unit built in the RF block 55 in the conventional optical disc apparatus. The error signal amplitude adjustment unit 60 includes a variable magnification amplifier 62 that can amplify the error signal to an arbitrary magnification, and is built in the RF block 55. An error signal 61 generated from an error signal from the pickup 53 is amplified by a variable magnification amplifier 62 and output as an adjusted error signal 63. The error signal amplitude adjusting unit 60 accurately measures the amplitude of the error signal 61 input from the pickup 53, and compares the measured amplitude value with the target error signal amplitude value. If the measured error signal amplitude value is different from the target error signal amplitude value,
(Target error signal amplitude value) / (Measured error signal amplitude value)
Is set in the variable magnification amplifier 62. The amplitude of the error signal 61 input from the pickup 53 is amplified by the variable magnification amplifier 62 so as to correspond to the target error signal amplitude, and is output as an adjusted error signal 63. As a result, in FIG. 8, the servo filter 57 to which the adjusted error signal 63 is input uses the error signal adjusted to a constant amplitude, no matter what disk or any pickup is used. It becomes possible to perform the calculation. For this reason, it is possible to prevent the reproduction ability from deteriorating with respect to disc types and pickup variations.

  However, if there is a light scratch on the surface of the optical disk to be reproduced, noise may occur when measuring the amplitude of the error signal, and the correct amplitude may not be measured. In this case, since the amplitude of the error signal is originally smaller than the target amplitude, noise is carried even though the error signal needs to be amplified to the target amplitude. It is erroneously determined that the amplitude of the error signal is larger than the target amplitude, and the amplitude of the error signal is attenuated. As a result, the adjustment of the amplitude for improving the reproduction capability of the disc adversely deteriorates the reproduction capability.

  In order to eliminate the noise on the error signal, the LPF is used for the above problems. That is, in the servo control LSI 54 of the optical disk apparatus of FIG. 8, the error signal from the pickup 53 is amplified by the RF block 55, and the noise carried on the error signal by the external LPF 56 mounted outside the servo control LSI 54. The component was removed. Here, the external LPF 56 can determine the cutoff frequency by a combination of resistance and capacitance, and a constant value is set depending on the purpose and application of use. The error signal having passed through the external LPF 56 is used for calculation by the servo filter 57 after the noise component in the high frequency region is removed. The cut-off frequency is normally set to a sufficiently high value with respect to the servo band, for example, 10 kHz. Here, the cut-off frequency indicates a specific frequency that serves as a threshold for allowing only frequencies below that to pass.

  However, in the above-described conventional optical disc apparatus, the external LPF 56 is intended to remove a noise component on the error signal during the servo operation, and the cut-off frequency is set to a frequency sufficiently higher than the servo band. Is done. Therefore, when there is a thin scratch on the surface of the optical disk to be reproduced and a noise component is added to the error signal, the noise component cannot be sufficiently removed at the cutoff frequency set in the external LPF 56. For this reason, it is impossible to accurately measure the amplitude value of the error signal, and the error signal amplitude including a noise component included in the error signal is erroneously measured, resulting in deterioration of reproduction capability. Become.

  The present invention has been made in order to solve the above-described problems, and has a high reproduction capability so that an error signal amplitude can be accurately measured without being affected by thin scratches on the surface of the optical disk to be reproduced. The purpose is to provide.

  In order to achieve the above object, an error signal amplitude value measuring method according to the present invention is an error measurement method for measuring the amplitude of an error signal output from an optical pickup through a filter unit that passes a signal having a specific frequency or less. A signal amplitude measuring method, comprising: a first step of lowering a specific frequency of the filter unit immediately before measuring the amplitude of the error signal; a second step of measuring the amplitude of the error signal; and immediately after measuring the error signal. And a third step of returning the specific frequency of the filter unit.

  According to this method, the error signal amplitude measuring method of the present invention has hitherto been done by setting the cut-off frequency of the filter unit that allows a signal below a specific frequency to pass only during the measurement of the amplitude of the error signal. Even when there is a light scratch on the surface and a noise component has been added to the measured error signal, the correct amplitude of the error signal from which the noise component has been removed can be measured. That is, an accurate error signal amplitude can be measured without being affected by noise. As a result, it is possible to realize an optical disc apparatus having a high reproduction capability that is not affected by thin scratches on the surface of the optical disc to be reproduced.

  The error signal may be either a focus error signal or a tracking error signal.

  When the error signal is a focus error signal, an accurate focus error signal amplitude can be measured, so that the beam spot of the optical disk reproducing apparatus can be accurately focused on the recording surface of the disk. As a result, it is possible to realize an optical disc apparatus having a high reproduction capability that is not affected by thin scratches on the surface of the optical disc to be reproduced.

  When the error signal is a tracking error signal, it is possible to accurately measure the tracking error signal amplitude, so that it is possible to accurately follow the track including the information of the disc on which the beam spot of the optical disc reproducing apparatus is reproduced. As a result, it is possible to realize an optical disc apparatus having a high reproduction capability that is not affected by thin scratches on the surface of the optical disc to be reproduced.

  The error signal includes a focus error signal and a tracking error signal, and the amplitude of the focus error signal is measured in the second step. The error signal amplitude measuring method further includes a measurement value of the focus error signal. Based on this, a fourth step of adjusting the amplitude of the focus error signal to be constant, a fifth step of lowering the specific frequency of the filter unit immediately before measuring the amplitude of the tracking error signal, and measuring the amplitude of the tracking error signal A sixth step, a seventh step for returning the specific frequency of the filter unit immediately after measurement of the tracking error signal, and a fourth step for adjusting the amplitude of the tracking error signal to be constant based on the measured value of the tracking error signal And may be included.

  As a result, the beam spot of the optical disk reproducing apparatus can be accurately focused on the recording surface of the reproduced disk, and can accurately follow the track including the information on the disk. As a result, it is possible to realize an optical disc apparatus having a high reproduction capability that is not affected by thin scratches on the surface of the optical disc to be reproduced.

  The error signal amplitude measurement method further includes a step of correcting the measured amplitude of the error signal using a correction factor that is determined in advance according to a difference between the specific frequency and the lowered frequency. But you can.

  As a result, even when the cutoff frequency of the LPF is set to a sufficiently low frequency relative to the servo band, that is, when the ratio of decreasing the amplitude of the error signal measured by lowering the cutoff frequency of the LPF increases. By correcting, the amplitude of the error signal can be measured more accurately. Therefore, it is possible to realize an optical disc apparatus having a high reproduction capability that is not affected by thin scratches on the surface of the optical disc to be reproduced.

  The filter unit includes a first filter and a second filter. In the first step, the specific frequency of the first filter is lowered, and the specific frequency of the second filter unit is set to a frequency different from that of the first filter. In the second step, the amplitude of the error signal that has passed through the first filter and the amplitude of the error signal that has passed through the second filter are measured. Determining whether the difference or ratio of two measured values is within a predetermined range, and determining that one of the two measured values is an amplitude of the error signal when determined to be within the predetermined range Good.

  The amplitude measurement method of the error signal may further include a specific frequency of the first filter unit and the second filter unit when it is determined that the difference or ratio between the two measured values is not within a predetermined range. And further performing a measurement and determination again.

  As a result, separate cutoff frequencies are set for the two types of LPFs, and the above-mentioned LPF cutoff frequency is kept until the difference or ratio of the amplitude values of the error signals to be measured is within a predetermined allowable range. Is set again and the measurement of the error signal amplitude is repeated. Then, the amplitude value of the error signal when it falls within the allowable predetermined range is acquired as a measurement result. Accordingly, it is possible to measure an error signal amplitude value that is not affected by noise, and it is possible to realize an optical disc apparatus having a high reproduction capability that is not affected by a thin scratch on the surface of the optical disc to be reproduced.

  According to the present invention, it is possible to realize an optical disc reproducing apparatus having a high reproduction capability capable of accurately measuring an error signal amplitude without being affected by a thin scratch or the like on the surface of an optical disc to be reproduced.

  The error signal amplitude measuring method according to the present invention is characterized in that when measuring the amplitude of the error signal, the cutoff frequency of the LPF is set low. Here, the time of measuring the amplitude of the error signal means the time of measuring the amplitude of the error signal, which is performed during the initial operation every time the optical disk is replaced. Thereby, even when a noise component is added to the measured error signal due to a thin scratch on the disk surface, only the noise component can be removed and the correct amplitude of the error signal can be measured.

  Hereinafter, an optical disk reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to an embodiment of the present invention. In FIG. 1, the optical disk apparatus includes a spindle motor 12 that rotates an optical disk 11, a pickup 13 that reads a signal from the optical disk 11, a servo control LSI 14 that performs servo control, and a servo control LSI 14. An RF block 15 that amplifies the signal, an LPF 16 that can freely change the cutoff frequency by setting, and an error signal that is generated by the RF block 15 and that has passed through the LPF 16 by cutting a high-frequency region that is equal to or higher than the cutoff frequency And a driver 18 for amplifying a signal from the servo filter 17 and driving the pickup 13 to a target point of the optical disk 11, and a control microcomputer 19 for controlling them. It has been. The RF block 55 and the external LPF 56 are built in the servo control LSI 54. However, since the external LPF 56 is realized by a digital filter, the cutoff frequency can be set by changing the setting of the servo LSI 54. It is possible.

  The LPF 16 capable of freely changing the cut-off frequency follows the error signal generated by the RF block 15 by changing the cut-off frequency of the LPF 16 to a low setting value only when measuring the amplitude of the error signal. Noise components can be removed.

  FIG. 2 is a diagram showing a normal error signal obtained when the error signal is measured when there is no scratch on the surface of the disc to be reproduced. Here, 21 indicates a normal error signal obtained when the error signal is measured, and 22 indicates the amplitude of the error signal defined by the length from the highest point to the lowest point.

  FIG. 3 is a diagram showing an error signal carrying a noise component when there is a light scratch or the like on the disk surface to be reproduced. Here, 30 indicates an error signal carrying a noise component. Reference numeral 31 denotes a noise component signal, and reference numeral 32 denotes an error signal amplitude when noise is applied.

  As shown in FIG. 2, when an error signal is measured on a disc having no scratches on the surface of the disc, an S-shaped normal error signal 21 is usually measured. As an example, an error signal having a frequency of about 1 kHz and an amplitude of about 2.0 V is measured at the time of tracking error measurement with a CD-DA disc.

  However, as shown in FIG. 3, when there is a light scratch on the surface of the disk for which the amplitude of the error signal is measured, an error signal 30 in which a noise component signal 31 is added to the normal error signal 21 is generated. appear. As an example, at the time of tracking error measurement with a CD-DA disc, the frequency of the noise component signal 31 reaches about 10 kHz and the amplitude reaches 300 mV. Therefore, if no measures are taken, the correct amplitude cannot be measured due to the noise component at the time of error signal measurement.

  Further, as described above, the conventional LPF is intended to remove noise on the error signal 21 during the servo operation. Therefore, the cutoff frequency is set to a frequency sufficiently higher than the servo band. . Usually, about 10 kHz to 20 kHz is used. Therefore, the noise component signal 31 on the error signal 21 cannot be removed at the cutoff frequency set to about 10 kHz. However, in the present invention, the LPF 16 can freely change the cutoff frequency. Therefore, by setting the cut-off frequency of the LPF 16 to a low setting value only when measuring the amplitude of the error signal 21, there is a light scratch on the surface of the optical disk to be reproduced, and the noise component signal 31 is added when measuring the amplitude of the error signal 21. Even if it is, the correct amplitude of the error signal 21 from which only the noise component signal 31 is removed can be measured.

  After the measurement of the error signal amplitude is completed, the cut-off frequency of the LPF 16 is returned to the conventional setting value, and the servo operation is performed by the error signal 21 adjusted so that the amplitude becomes constant, and the disk is reproduced. .

  Therefore, even when the surface of the disk is thin, it is possible to accurately measure the amplitude of the error signal and to realize an optical disk reproducing apparatus having high reproduction performance.

  FIG. 4 is a flowchart showing the process of measuring the amplitude of the error signal.

  At the start of error signal amplitude measurement (S101), the control microcomputer 19 changes the cut-off frequency of the LPF 16 to a low set value according to the command setting (S102). For example, the setting value of the cutoff frequency of the normal LPF 16 is set to 10 kHz, and the setting value of the cutoff frequency of the LPF 16 at the time of error signal amplitude measurement is set to 4 kHz.

  Next, the amplitude of the error signal from which the noise component signal 31 has been removed is measured (S103), and the measured amplitude value of the error signal is acquired (S104).

  After measuring the amplitude of the error signal, the cutoff frequency of the LPF 16 is returned to the conventional setting value that is the setting value before the change (S105), and the error signal is adjusted so that the amplitude becomes constant, for example, tracking, focusing, etc. The servo operation is performed.

  Note that after the measurement of the amplitude of the error signal is completed, the cutoff frequency of the LPF 16 may be returned to the conventional setting value that is the setting value before the change (S105) after the error signal is adjusted so that the amplitude becomes constant. .

  Here, as an error signal whose amplitude is measured and adjusted every time the optical disk is replaced, a focus error signal indicating the defocus of the beam spot of the laser beam emitted from the pickup 13 with respect to the optical disk 11 or information on the optical disk 11 is used. This is a tracking error signal indicating the deviation between the recorded track and the position of the beam spot of the laser light emitted from the pickup 13. When the error signal to be measured is a focus signal, the cutoff frequency of the LPF 16 is changed according to the procedure shown in FIG. 4 with respect to the focus error signal. In other words, by switching the LPF cutoff frequency only when measuring the amplitude of the focus error signal, it is possible to perform accurate amplitude measurement without being affected by light scratches on the disk surface. Also, when the error signal to be measured is a tracking error signal, similarly, the cutoff frequency of the LPF 16 is changed with respect to the tracking error signal by the procedure shown in FIG. By switching the LPF cut-off frequency only when measuring the amplitude of the tracking error signal, accurate amplitude measurement can be performed without being affected by a thin scratch on the disk surface.

  Further, both the focus error signal and the tracking error signal may be used as the error signal whose amplitude is measured and adjusted every time the optical disk is replaced. In this case, first, the cut-off frequency of the LPF 16 is lowered with respect to the focus error signal according to the procedure shown in FIG. Then, the amplitude is adjusted based on the accurate amplitude measurement value. Next, with respect to the tracking error signal, the cut-off frequency of the LPF 16 is lowered according to the procedure shown in FIG. Then, the amplitude is adjusted based on the accurate amplitude measurement value. By implementing these, it is possible to accurately measure the amplitude of the focus error signal and the tracking error signal without being affected by the thin scratches on the disk surface.

  As a result, it is possible to realize an optical disc apparatus having a high reproduction capability that is not affected by thin scratches on the surface of the optical disc to be reproduced.

  As described above, it is possible to accurately measure the amplitude of the error signal even when the surface of the disk to be reproduced has a thin scratch or the like, and to realize a disk device having a high reproduction capability.

(Modification 1 of embodiment)
Hereinafter, Modification 1 of the embodiment of the present invention will be described.

  When measuring the amplitude of the error signal in the optical disk reproducing apparatus of FIG. 1, if the cutoff frequency of the LPF 16 is set to a sufficiently low frequency with respect to the servo band, the amplitude of the error signal to be measured is affected by the LPF 16. However, it is measured with a slightly different value compared to the actual error signal amplitude. For example, when a disc is reproduced by a disc reproducing apparatus, the cutoff frequency of the LPF 16 is normally set to 10 kHz, and the cutoff frequency of the LPF 16 at the time of error signal amplitude measurement is set to 4 kHz. When the frequency of the noise component in the error signal is 10 kHz, the amplitude measured when the LPF cutoff frequency is set to 4 kHz, compared to the amplitude measured when the cutoff frequency of the LPF 16 is set to 10 kHz. Becomes a small value.

  However, this smaller ratio is determined or calculated in advance by actual measurement. Therefore, the cut-off of the LPF 16 is corrected by correcting the amplitude of the error signal measured using a smaller ratio (hereinafter referred to as a correction factor) determined or calculated in advance according to the lowered frequency difference. The correct error signal amplitude measurement is possible without being affected by lowering the frequency.

  FIG. 5 is a flowchart showing the process of measuring the amplitude of the error signal in the first modification of the embodiment of the present invention.

  First, at the start of measurement of the error signal amplitude (S101), the cutoff frequency of the LPF 16 is changed to a low setting value (S102).

  Next, the error signal amplitude from which the noise component has been removed is measured (S103), and the error signal amplitude measurement value is acquired (S104).

  Next, the amplitude measurement value of the error signal is corrected using a correction factor determined or calculated in advance (S1041).

  After correcting the amplitude measurement value of the error signal, the cutoff frequency of the LPF 16 is returned to the conventional setting value that is the setting value before the change (S105), and for example, tracking is performed using the error signal adjusted so that the amplitude becomes constant. Servo operations such as focusing and focusing.

  Thereby, even when the cutoff frequency of the LPF 16 is set to a sufficiently low frequency with respect to the servo band, it is possible to accurately measure the amplitude of the error signal. That is, since the amplitude of the error signal measured by lowering the cutoff frequency of the LPF 16 is smaller than the actual error signal, the amplitude of the error signal to be measured needs to be amplified. For this reason, the amplitude of the error signal measured using a correction factor determined or calculated in advance is amplified.

  Note that the cutoff frequency of the LPF 16 is returned to the conventional setting value that is the setting value before the change (S105) before the error signal amplitude measurement value is corrected (S1041), and the amplitude is constant. The error signal may be adjusted so that

  Similarly to the above-described embodiment, the error signal to be measured is a focus error signal or a tracking error signal, and may be both a focus error signal and a tracking error signal.

  As described above, even when the cut-off frequency of the LPF 16 is set to a sufficiently low frequency with respect to the servo band, the error signal can be accurately corrected by performing correction using a correction factor determined in advance according to the lowered frequency difference. Amplitude measurements can be performed. Therefore, even when a disk having a thin scratch on the surface is reproduced, it is possible to realize an optical disk reproducing apparatus having a high reproduction ability without being affected by the reproduction.

(Modification 2 of embodiment)
Hereinafter, Modification 2 of the embodiment of the present invention will be described.

  As described in the first modification of the embodiment, it is possible to predict how much the amplitude of the error signal measured by lowering the cutoff frequency of the LPF will decrease, and a correction determined or calculated in advance. By using the rate, it is possible to obtain a more accurate error signal amplitude. However, even if the cut-off frequency of the LPF is lowered sufficiently and the amplitude of the error signal is measured, it is not known whether the noise component is sufficiently removed. In the second modification, different cutoff frequencies are set for the two types of LPFs, and error signals are measured. Until the ratio or difference of the measured amplitude values of the error signal is within a predetermined range, the LPF cutoff frequency is reset again and the measurement of the amplitude value of the error signal is repeated. This makes it possible to measure the error signal amplitude value more accurately without being affected by noise.

  FIG. 6 is a block diagram showing a configuration of an optical disc reproducing apparatus in the second modification of the embodiment of the present invention. In FIG. 6, the optical disk reproducing apparatus is built in a spindle motor 12 that rotates the optical disk 11, a pickup 13 that reads a signal from the optical disk 11, a servo control LSI 14 that performs servo control, and a servo control LSI 14. Using the RF block 15 that amplifies the signal, two LPFs 161 and 162 that can freely change the setting of the cut-off frequency, and the error signal generated by the RF block and passed through the LPFs 161 and 162, The servo filter 17 that performs servo calculation, the driver 18 that amplifies the signal from the servo filter 17 and drives the pickup 13 to the target point of the optical disk 11, and the control microcomputer 19 that controls them are configured.

  In FIG. 6, separate cutoff frequencies are set for the LPFs 161 and 162, respectively, and the amplitude of the error signal is measured. If the ratio or difference between the measured values is within a predetermined range, the measured error signal is judged to have no noise due to light scratches, that is, removed, and the measured amplitude is determined. To do. Within the predetermined range is a range of acceptable ratio values that can be determined that no noise is present, for example, 1 ± 0.1, and a range of acceptable difference values that can be determined that no noise is present. is there. If the ratio or difference between the measured values is outside the predetermined range, it is determined that noise is added to the measured error signal, and the cutoff frequencies of the LPFs 161 and 162 are further lowered to reduce the error signal. Perform the amplitude measurement again.

  FIG. 7 is a flowchart showing processing for measuring the amplitude of the error signal in the first modification of the embodiment of the present invention.

  First, at the start of error signal amplitude measurement (S101), the cutoff frequencies of the two LPFs 161 and 162 are changed to different low setting values (S102).

  Next, the measurement of each error signal amplitude from which the noise components have been removed through the LPFs 161 and 161 is performed (S103).

  If the ratio or difference between the measured amplitude values is determined to be within a predetermined range, the measured error signal is determined to be free from noise due to light scratches, and the measured amplitude is determined. decide. If the ratio or difference between the measured values is outside the predetermined range, it is determined that noise is added to the measured error signal, and the cutoff frequencies of the LPFs 161 and 162 are further lowered to reduce the error signal. The amplitude measurement is performed again (S203).

  At this time, until it is determined that the ratio or difference between the measured values is within a predetermined range and the amplitude value of the measured error signal is determined, the cut-off frequency of the LPFs of S102, 103, and S203 is lowered to reduce the error. Measuring the amplitude of the signal is performed repeatedly.

  Next, the measured amplitude value of the error signal determined in S203 is acquired (S104).

  Here, the amplitude value determined in the LPFs 161 and 162 is used as the determined amplitude value. For example, the amplitude value measured by the LPF 161 or the LPF 162 may be used. Furthermore, the average of the amplitude value measured by the LPF 161 and the amplitude value measured by the LPF 162 may be used.

  After obtaining the error signal amplitude measurement value, the cutoff frequencies of the LPFs 161 and 162 are returned to the conventional setting values that are the setting values before the change (S105), and the error signal 21 adjusted so that the amplitude becomes constant is used. For example, servo operations such as tracking and focusing are performed. As a result, by using the two LPFs 161 and 162 that can set the cut-off frequency separately, it is possible to accurately measure the amplitude of the error signal and not be affected by light scratches on the surface of the optical disc to be reproduced. An optical disc apparatus with high reproduction capability can be realized.

  Here, as in the embodiment, the amplitude of the error signal to be measured and adjusted is a focus error signal or a tracking error signal. Furthermore, both a focus error signal and a tracking error signal may be used.

  Note that after the measurement of the amplitude of the error signal is completed, the cutoff frequency of the LPF 16 may be returned to the conventional setting value that is the setting value before the change (S105) after the error signal is adjusted so that the amplitude becomes constant. .

  As mentioned above, although this invention demonstrated the optical disk reproducing | regenerating apparatus based on Embodiment, the modification 1 of Embodiment, and the modification 2 of Embodiment, this invention is limited to this Embodiment. Not. For example, an apparatus for writing on an optical disk such as a CD-RW or CD-R is also included in the scope of the present invention if the optical disk reproducing mechanism described in the present invention is included.

  The present invention can be used for an optical disk device, and in particular, for an optical disk reproducing device such as a CD player, a DVD player, or a Blu-Ray player.

It is a block diagram which shows the structure of the optical disk reproducing | regenerating apparatus in embodiment of this invention. It is a figure which shows the normal error signal obtained when an error signal is measured when there is no flaw etc. on the surface of the disc to be reproduced in the embodiment of the present invention. It is a figure which shows the error signal which has a noise component when there exists a thin crack etc. on the disc surface to reproduce | regenerate in embodiment of this invention. It is a flowchart which shows the process of the amplitude measurement of the error signal in embodiment of this invention. It is a flowchart which shows the process of the amplitude measurement of the error signal in the modification 1 of embodiment of this invention. It is a block diagram which shows the structure of the optical disk reproducing | regenerating apparatus in the modification 2 of embodiment of this invention. It is a flowchart which shows the process of the amplitude measurement of the error signal in the modification 2 of embodiment of this invention. It is a block diagram which shows the structure of the conventional optical disk apparatus. It is a block diagram which shows the structure of the error signal amplitude adjustment part in the conventional conventional optical disk apparatus.

Explanation of symbols

11 Optical disk 12 Spindle motor 13 Pickup 14 Servo control LSI
15 RF block 16 LPF
161 LPF
162 LPF
17 Servo Filter 18 Driver 19 Control Microcomputer 21 Normal Error Signal 22 Amplitude in Normal Error Signal 30 Noise Signal with Noise 31 Signal of Noise Component 32 Amplitude in Error Signal with Noise 51 Optical Disc 52 Spindle Motor 53 Pickup 54 Servo Control LSI
55 RF block 56 External LPF
57 Servo filter 58 Driver 59 Control microcomputer 61 Error signal from pickup 62 Variable magnification amplifier 63 Error signal after adjustment

Claims (7)

In an optical disk reproducing apparatus, an error signal amplitude measuring method for measuring an amplitude of a focus error signal output through a filter unit that allows a signal having a specific frequency or less to pass from an optical pickup,
A first step of lowering a specific frequency of the filter unit just before the focus error signal can pass, just before measuring the amplitude of the focus error signal;
A second step of measuring the amplitude of the focus error signal;
A third step of returning the specific frequency of the filter unit to a value before amplitude measurement in the second step immediately after measurement of the focus error signal;
An error signal amplitude measuring method comprising: a fourth step of adjusting the amplitude of the focus error signal to be constant based on the measurement value of the focus error signal measured in the second step. In an optical disk reproducing apparatus, an error signal amplitude measuring method for measuring an amplitude of a tracking error signal output through a filter unit that passes a signal having a specific frequency or less from an optical pickup,
A first step of lowering the specific frequency of the filter unit immediately before the measurement of the amplitude of the tracking error signal within a range in which only the tracking error signal can pass;
A second step of measuring the amplitude of the tracking error signal;
A third step of returning a specific frequency of the filter unit to a value before amplitude measurement in the second step immediately after measurement of the tracking error signal;
An error signal amplitude measuring method comprising: a fourth step of adjusting the amplitude of the tracking error signal to be constant based on the measured value of the tracking error signal measured in the second step. The method for measuring the amplitude of the error signal further includes:
The method includes a step of correcting the amplitude of the measured error signal using a predetermined correction factor according to a difference between the specific frequency and the frequency lowered in the first step. 3. The error signal amplitude measuring method according to 1 or 2. The filter unit includes a first filter and a second filter,
In the first step, the specific frequency of the first filter is lowered, the specific frequency of the second filter unit is lowered to a frequency different from that of the first filter,
Measuring the amplitude of the error signal passing through the first filter and the amplitude of the error signal passing through the second filter in the second step;
The method for measuring the amplitude of the error signal further includes:
Determining whether the difference or ratio between the two measured values is within a predetermined range;
3. The error signal amplitude measuring method according to claim 1, wherein, when it is determined that the frequency is within the predetermined range, the higher one of the two measured values is determined as the amplitude of the error signal. 4. The method for measuring the amplitude of the error signal further includes:
When it is determined that the difference or ratio between the two measured values is not within the predetermined range, the specific frequency of the first filter unit and the second filter unit is further lowered, and measurement and determination are performed again. The error signal amplitude measuring method according to claim 4, further comprising: Filter means for passing frequencies below a specific frequency;
Measuring means for measuring the amplitude of a focus error signal output from the optical pickup through the filter unit;
The lower the specific frequency of the filter portion to the amplitude immediately before measurement of the focus error signal within the range where only can pass the focus error signal, the amplitude of the error signal a particular frequency of the filter unit immediately after the amplitude measurement of the error signal And a changing means for returning to the value before the measurement ,
On the basis of the measured value of the said focus error signal by the measuring means, the optical disk reproducing apparatus, characterized in that that to adjust the amplitude of the focus error signal constant.   Filter means for passing frequencies below a specific frequency;
  Measuring means for measuring the amplitude of the tracking error signal output from the optical pickup through the filter unit;
  Immediately before measuring the amplitude of the tracking error signal, the specific frequency of the filter unit is lowered within a range where only the tracking error signal can pass, and immediately after measuring the amplitude of the error signal, the specific frequency of the filter unit is measured. Changing means for returning to the previous value,
  Based on the measured value of the tracking error signal measured by the measuring means, the amplitude of the tracking error signal is adjusted to be constant.
  An optical disk reproducing apparatus characterized by the above.

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