JP2007293947A - Device for measuring groove transverse signal of optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To offer a device for measuring a groove-crossing signal, by which a level of the groove-crossing signal contained in a focus error signal can be measured without being affected by a loop characteristic of a focus servo circuit in an optical pickup of an optical disk player. <P>SOLUTION: The device is equipped with: a frequency detector (21) for receiving an input of a tracking error signal having the same period as that of the groove-crossing signal to detect a frequency of the tracking error signal; a process block (23) for obtaining gain data by referring to a preset frequency-gain table on the basis of the detected frequency from the frequency detector (21) while only the focus servo is applied; and a gain correcting device (25) for receiving an input of the focus error signal containing the groove-crossing signal and correcting the gain by the obtained gain data to output the focus error signal containing the corrected groove-crossing signal to a measurement process block (26). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical pickup groove crossing signal measuring apparatus for measuring a groove crossing signal included in a focus error signal in a focus servo circuit of an optical pickup.

  When the signal recorded on the optical disk is reproduced using the optical pickup, the focus servo is applied to the optical pickup so that the reproduction laser beam from the optical pickup scans the track on the optical disk while focusing.

  When the astigmatism method is adopted as the focus error detection method of the optical pickup, the reproduction laser beam is diffracted by the track groove when traversing the track on the optical disk due to the aberration of the optical system and the lack of defocus adjustment. The intensity distribution in the reflected light flux becomes asymmetric and is not canceled by the diagonal sum differential calculation of the astigmatism method and is mixed as a disturbance in the focus error signal. This disturbance is called a “groove crossing signal” and adversely affects the focus servo operation. FIG. 9A shows the waveform of a focus error signal that does not include a groove crossing signal. FIG. 9B shows a waveform of a focus error signal including a groove crossing signal.

  Conventional techniques for reducing or canceling the groove crossing signal in the focus error signal described above are described in Japanese Patent Laid-Open Nos. 4-168863 (hereinafter, Patent Document 1) and Japanese Patent Laid-Open No. 8-279166 (hereinafter, Patent Document 2). There is an "optical pickup device".

  In the technique described in Patent Document 1, a plurality of focus error signals obtained by dividing a beam incident on an optical disk are calculated to cancel a groove crossing signal, that is, cross noise.

  On the other hand, in the technique described in Patent Document 2, the groove crossing signal, that is, disturbance is canceled by the differential astigmatism method.

  However, these Patent Documents 1 and 2 do not describe any measurement of the groove crossing signal itself.

  A method for measuring a groove crossing signal, that is, a disturbance due to groove crossing, is described in Japanese Patent Laid-Open No. 8-50730 (hereinafter referred to as Patent Document 3). In Patent Document 3, the rotation of the optical disk or the actuator in the radial direction of the optical disk is controlled so that the frequency is not affected by the focus gain, that is, the frequency equal to or higher than the gain intersection.

  However, since the influence of the servo circuit exists even in the band beyond the gain intersection, the measuring method described in Patent Document 3 cannot measure the true value of the groove crossing signal.

Japanese Patent Laid-Open No. 2001-84605 (hereinafter referred to as Patent Document 4) also describes a method for measuring a groove crossing signal, that is, a groove signal. In Patent Document 4, a signal across a groove is measured by processing a signal before phase compensation. However, in this measurement method, even if the influence of the open loop gain characteristic can be removed, the influence of the closed loop gain characteristic and the E (s) / W (s) gain characteristic cannot be excluded. The true value of cannot be measured.
Japanese Laid-Open Patent Publication No. 4-168631 (page 3 and FIGS. 1 and 2) JP-A-8-279166 (pages 5 and 6 and FIGS. 3 and 5) JP-A-8-50730 (pages 4 and 5 and FIGS. 1 and 2) JP, 2001-84605, A (page 8 and FIG. 1) Next, with reference to FIG. 10, the focus error signal in the focus servo circuit of the optical pick-up provided with the groove crossing signal measurement block in the general optical disk reproducing | regenerating apparatus. The configuration of the groove crossing signal measuring device included in FIG.

  In FIG. 10, the optical disk 1 is rotated by a spindle motor 2, and the rotation of the motor 2 is controlled by a control unit 11.

  Laser light from the laser diode 6 enters the polarization beam splitter 5 and is reflected by the reflection surface. The reflected light further enters the reflecting mirror 4 and is reflected by the reflecting surface. The reflected light enters the objective lens 3 and is focused so as to be focused on the recording surface of the optical disc 1. The objective lens 3 is attached to the actuator 18. The actuator 18 is subjected to focus servo and tracking servo by the control unit 11. The laser output of the laser diode 6 is controlled by the control unit 11.

  The reflected light from the recording surface of the optical disk 1 passes through the objective lens 3 and enters the reflecting mirror 4, and the reflected light passes through the polarization beam splitter 5 and is then condensed by the condenser lens 7 to be subjected to photoelectric conversion. The light is incident on the light receiving surface of the device 8 so as to be focused. The sum signal from different diagonal conversion units of the four-divided photoelectric conversion unit of the photoelectric converter 8 is supplied to the differential amplifier 9 and differentially amplified to generate a focus error signal. The generated focus error signal is supplied to the controller 11 through the phase compensator 10 and to the groove crossing signal measurement block 12. Note that the sum signal from the two conversion units located on both sides of the track of the four-divided photoelectric conversion unit of the photoelectric converter 8 is supplied to the differential amplifier 9 and differentially amplified to obtain a tracking error signal. . When measuring the groove crossing signal, only the focus servo is applied to the actuator 18, and the tracking servo is not applied.

  Next, a focus servo circuit in the optical disk reproducing apparatus of the groove crossing signal measuring apparatus in FIG. 10 will be described with reference to FIG. In the following formula, s represents jω of Laplace transform. The positions of the objective lens 3 and the actuator 18 are assumed to be equal.

  The difference between the target value R (s) indicating the position of the recording surface of the optical disc 1 and the displacement C (s) as the position of the objective lens 3, that is, the actuator 18, is obtained by the subtractor 13 and includes a groove crossing signal. No focus error signal F (s) is generated. The signal F (s) is mixed with the groove crossing signal W (s) as a disturbance, and the sum signal is supplied to the error signal detector (ESD) 15. The error signal detector 15 has a total transmission element Gesd (s) of a focus error calculation circuit including a photoelectric converter 8 and a differential amplifier 9 as transmission elements, and a focus error signal E (s) including a groove crossing signal W (s). ) Is generated.

  The focus error signal E (s) is supplied to a low pass filter (LPF) 16. Glpf (s) represents a transfer element of the low-pass filter 16. The output of the low-pass filter 16 is supplied to the actuator 18 through the lead lug filter 17. Gllf (s) represents a transmission element of the lead lag filter 17, that is, a total transmission element of the drive signal forming circuit of the phase compensator 10 and the actuator 18. Gact (s) indicates a transmission element of the actuator 18.

  As described above, the displacement C (s) of the objective lens 3, that is, the actuator 18 is supplied to the subtractor 13 and subtracted from the target value R (s) indicating the position of the recording surface of the optical disc 1. The total gain G of the error signal detector (ESD) 15, the low-pass filter 16, the lead lag filter 17, and the actuator 18 is expressed by the following equation (1).

[Equation 1]
G = Gesd (s) · Glpf (s) · Gllf (s) · Gact (s) (1)
Since the frequency characteristics of the photoelectric converter 8 and the differential amplifier 9 extend to a band sufficiently higher than the servo band, the transfer element Gesd (s) of the error signal detector 15 does not affect the total gain G. Absent. The focus error signal E (s) is actually converted from an optical signal to an electric signal in the photoelectric converter 8, but the frequency characteristics of the photoelectric converter 8 are generally guaranteed up to around 100 MHz. In considering the servo band, the transfer element Gesd (s) of the error signal detector 15 is not affected.

  The waveform of the groove crossing signal of each example of the focus servo circuit of the optical pickup of the three different types of optical disk reproducing apparatuses, together with the waveform of the displacement C (s) of the objective lens 3 and the tracking error signal TE having the same cycle as the groove crossing signal. 12 (A), (B), and (C). In these waveforms of FIGS. 12A, 12B, and 12C, the waveform of the groove crossing signal and the waveform of the displacement C (s) of the objective lens 3 are different from each other, but the waveform of the tracking error signal TE is the same. is there.

  13A, 13B, and 13C show the open loop gain characteristic and phase characteristic of the focus servo circuit of the optical pickup of three different types of optical disc reproducing apparatuses, respectively.

  In FIGS. 13A, 13B, and 13C, the horizontal axis represents frequency (Hz), the left vertical axis represents gain (dB), and the right vertical axis represents phase ( Phase) [Deg].

  In FIGS. 13A, 13B, and 13C, the gain crossover frequencies are 1.4 kHz, 1.0 kHz, and 2.0 kHz, respectively, and the phase margin angles are 60 Deg, 20 Deg, and 40 Deg, respectively.

  The open loop transfer function G of the focus servo circuit of FIG. 11 is expressed as shown in the following equation (2). Here, F (s) represents a focus error signal not including a groove crossing signal, and C (s) represents a displacement of the objective lens 3.

[Equation 2]
C (s) / F (s) = G (s) (2)
The closed loop transfer function G / (1 + G) of the focus servo circuit of FIG. 11 is expressed as shown in the following equation (3). Here, R (s) is a target value indicating the position of the recording surface of the optical disc 1.

[Equation 3]
C (s) / R (s) = G / (1 + G) (3)
As described above, the open-loop and closed-loop gain characteristics of the focus servo circuit of the optical pickup of three different types of optical disk playback apparatuses are shown in FIGS. 14A, 14B, and 14C, respectively.

  As shown in FIGS. 14A, 14 </ b> B, and 14 </ b> C, lifting occurs in a band in the frequency characteristics according to the gain intersection and the phase margin. When the frequency of the groove crossing signal is changed due to the eccentricity due to this characteristic, the signal level that is originally flat without depending on the frequency changes according to the frequency characteristic. In FIGS. 14A, 14B, and 14C, the horizontal axis represents frequency (Hz), the left vertical axis represents open loop gain (Gain) [dB], and the right vertical axis represents The closed loop gain (Gain) [dB] is shown respectively. As can be seen from FIG. 14, the frequency and gain of the peak (maximum point) of the closed-loop gain frequency characteristic curves of three different types of optical disk playback devices are 0.8 kHz; 1.3 dB, 0.9 kHz; 3.8 dB, 1 .5 kHz; 1.6 dB, which are different from each other. This is due to the difference in loop characteristics of the focus servo circuit of the optical disk reproducing apparatus.

  As described above, according to the conventional groove crossing signal measuring device, the measurement result is affected by the loop characteristics of the focus servo circuit constituting each device, and the groove crossing signal cannot be measured accurately. There was a problem.

  In view of the above circumstances, the present invention provides a groove crossing signal measurement capable of accurately measuring the level of the groove crossing signal included in the focus error signal without being affected by the loop characteristic of the focus servo circuit of the optical pickup of the optical disk reproducing apparatus. The object is to provide a device.

  In order to achieve the above object, according to the present invention, in claim 1, during reproduction of data recorded on an optical disk by an optical pickup, a track groove is formed when a reproducing laser beam of the optical pickup crosses a track on the optical disk. In the groove crossing signal measuring device of the optical pickup having a measurement processing unit for measuring the level of the groove crossing signal mixed in the focus error signal due to the influence of the tracking error signal, the tracking error signal having the same period as the groove crossing signal is With reference to a preset frequency-gain table based on the detection frequency of the frequency detection unit and the frequency detection unit that detects the frequency of the tracking error signal supplied and only the focus servo is applied. A gain calculation unit for obtaining gain data and a focus error signal including the groove crossing signal are supplied. , Corrected by the gain data obtained the gain at the gain calculation unit is characterized in that a gain correction unit for outputting a focus error signal including the corrected groove crossing signal to the measurement processing unit.

  According to a second aspect of the present invention, during reproduction of data recorded on an optical disc by an optical pickup, a focus error signal is generated due to the influence of a track groove when the reproduction laser beam of the optical pickup crosses a track on the optical disc. In a groove crossing signal measuring device of an optical pickup having a measurement processing unit for measuring the level of a mixed groove crossing signal, a focus error signal including the groove crossing signal is supplied, and a focus error signal determined by transfer characteristics of a focus servo system / A filter unit for correcting with the gain characteristic of the groove crossing signal, and a high-pass filter unit for cutting low-frequency fluctuations of the focus error signal including the corrected groove crossing signal are provided.

  According to a third aspect of the present invention, during reproduction of data recorded on an optical disk by an optical pickup, a focus error signal is generated due to the influence of a track groove when the reproduction laser beam of the optical pickup crosses a track on the optical disk. In an optical pickup groove crossing signal measurement device equipped with a measurement processing unit for measuring the level of the mixed groove crossing signal, a tracking error signal having the same period as the groove crossing signal is supplied, and the frequency of this tracking error signal is detected. And a binarization circuit unit that is supplied with a detection frequency of the frequency detection unit and executes binarization processing with a threshold value determined in advance from the gain characteristic of the focus error signal / groove crossing signal; The focus error signal including the groove crossing signal is masked by the signal generated by the binarization process. And a gate circuit unit that performs correction to extract only a band portion that is not affected by the gain increase in the focus error signal and outputs a focus error signal including the corrected groove crossing signal to the measurement processing unit. It is characterized by that.

  According to the optical pickup groove crossing signal measuring apparatus of the present invention, the level of the groove crossing signal included in the focus error signal is accurately measured without being affected by the loop characteristic of the focus servo circuit of the optical pickup of the optical disk reproducing apparatus. be able to.

  Hereinafter, an embodiment of an optical pickup groove crossing signal measuring apparatus according to the present invention will be described. Since the basic configuration of the optical disk reproducing apparatus to which the present invention is applied is the same as that in FIG. 10, the following embodiment will be described with reference to FIG.

<First Embodiment>
FIG. 1 is a block diagram showing a configuration of a first embodiment of an optical pickup groove crossing signal measuring apparatus according to the present invention, and FIG. 2 is a waveform diagram showing signal waveforms of respective parts shown in FIG. The groove crossing signal measuring apparatus shown in FIG. 1 corresponds to the crossing signal measuring block 12 in the optical disk reproducing apparatus of FIG.

  As shown in FIG. 1, the groove crossing signal measuring apparatus 20A according to the first embodiment receives a tracking error signal TE and detects the frequency of the groove crossing signal W (s) included in the tracking error signal TE. A detector 21, an A / D converter 22 for A / D converting the frequency component of the groove crossing signal W (s) detected by the frequency detector 21, and a frequency stored in the ROM including the ROM− Based on the gain table, a processing block 23 for obtaining a gain from the A / D converted frequency component a, a D / A converter 24 for D / A converting the gain data calculated in the processing block 23, and a focus error A gain corrector 25 that receives the signal E (s) and outputs the focus error signal from the D / A converter and corrects it with the gain data is provided, and the gain is corrected. Is configured to supply Okasuera signal W1 (s) is to measurement processing block 26.

  Next, the operation of the first embodiment will be described.

  In the above configuration, when the groove crossing signal W (s) is measured, the actuator 18 shown in FIG. 10 is operated with focus servo applied and without tracking servo applied. In this state, a tracking error signal TE having the same period as the groove crossing signal is supplied to the frequency detector 21 to perform frequency detection. The frequency (kHz) -voltage (V) characteristics of the frequency detector 21 are in a linear relationship here as shown in FIG. The detection output of the frequency detector 21 is supplied to the A / D converter 22, converted into a digital signal a, and then supplied to the processing block 23. In the processing block 23, the digital gain corresponding to the frequency of the digital signal a is output by referring to the frequency-gain table of E (s) / W (s) by the input digital signal a. The digital gain is supplied to the D / A converter 24, converted into an analog form, and supplied to the gain corrector 25. The gain corrector 25 corrects the gain of the focus error signal E (s) including the groove crossing signal according to the frequency of the frequency detector 21. The focus error signal W1 (s) whose gain has been corrected is supplied to the measurement processing block 26.

  In the measurement processing block 26, as shown in FIG. 4, the groove crossing signal W (s) is obtained by sampling the focus error signal W1 (s) whose gain is corrected to obtain a frequency distribution and extracting positive and negative peaks. The level of is measured. The measurement processing block 26 enables level measurement in consideration of variations in distribution of maximum and minimum levels.

<Second Embodiment>
Next, with reference to FIG. 5, the structure of the groove crossing signal measuring apparatus according to another embodiment (second embodiment) of the present invention will be described. 5 also corresponds to the crossing signal measurement block 12 in the optical disc reproducing apparatus of FIG.

  As shown in the figure, the groove crossing signal measuring device 20B of the second embodiment has the transfer characteristic of the open loop total gain characteristic G shown in FIG. 11 including the groove crossing signal and the characteristic of gain “1”. The added characteristic is increased by a filter circuit 27 constituted by an operational amplifier or a digital filter, and the output of the filter circuit 27 is gained by a cut-off frequency at which a gain “1” is obtained from the gain characteristic of the focus error signal / groove crossing signal. And a high-pass filter unit 28 that performs correction for cutting the band and outputs the focus error signal W2 (s) including the corrected groove crossing signal to the measurement processing block 26.

  Next, the operation of the second embodiment will be described.

  In the focus servo circuit shown in 11 of FIG. 10 and the block diagram of FIG. 11, since the groove crossing signal W (s) does not include the transmission element, the focus error signal F (s) that does not include the groove crossing signal, the optical disc 1 The approximate expression shown in the following expression (4) is established between the target value R (s) indicating the position of the recording surface, that is, the disk surface, the focus error signal E (s), and the groove crossing signal W (s). .

[Equation 4]
F (s) / R (s) ≈E (s) / W (s) (4)
For this reason, the approximate expression shown in the following expression (5) is established from the above expressions (2) to (4).

[Equation 5]
E (s) / W (s) ≈1 / (1 + G) (5)
When this equation (5) is modified, an approximate equation of the following equation (6) is obtained.

[Equation 6]
W (s) ≈ (1 + G) E (s) (6)
Therefore, the filter circuit 27 shown in FIG. 5 receives the focus error signal E (s) mixed with the groove crossing signal, and E (s) / W ((C) in FIGS. 6A, 6B, and 6C). A groove crossing signal W (s) is generated from the focus error signal E (s) through the inverse characteristic of the gain characteristic of s). Since the low-pass gain is high, the groove crossing signal W (s) fluctuates with a slight difference. Therefore, a filter is used for the purpose of removing this. The frequency is 1 kHz or less. 6A, 6B, and 6C, the horizontal axis represents frequency [Hz], and the vertical axis represents gain [dB].

  In the measurement processing block 26, as shown in FIG. 4, the level of the groove crossing signal W (s) is measured by sampling the output signal W2 (s) to obtain a frequency distribution and extracting positive and negative peaks. . The measurement processing block 26 enables level measurement in consideration of variations in distribution of maximum and minimum levels.

<Third Embodiment>
Next, the configuration of a groove crossing signal measurement block according to still another embodiment (third embodiment) of the present invention will be described with reference to FIG. 7 also corresponds to the crossing signal measurement block 12 in the optical disk reproducing apparatus of FIG. FIG. 8 is a waveform diagram showing signal waveforms of the respective parts shown in FIG.

  As shown in FIG. 7, the groove crossing measuring apparatus 20C in the third embodiment receives a tracking error signal having the same period as the groove crossing signal, and a frequency detector 21 for detecting the frequency of this tracking error signal; Then, the detection frequency of the frequency detection unit is input, and binarization processing for selecting a frequency at which the gain becomes “1” by a threshold value determined in advance from the gain characteristic of the focus error signal / groove crossing signal is executed 2 Masking the focus error signal including the groove crossing signal with the frequency selected by the binarization circuit 29 and the binarization process to extract only the band portion not affected by the gain increase in the focus error signal And a gate circuit 30 that outputs a focus error signal including the corrected groove crossing signal to the measurement processing block 28; It is provided.

  Next, the operation of the third embodiment will be described.

  A tracking error signal TE having the same period as the groove crossing signal is supplied to the frequency detector 21, and frequency detection is executed. The frequency (kHz) -voltage (V) characteristic of the frequency detector 21 has a linear relationship (linear relationship) as shown in FIG. The detection output b of the frequency detector 21 is supplied to the binarization circuit 29 to obtain the binarization output c. This binarized output c is supplied to the gate circuit 30 as a trigger for the masking pulse. In this case, as the threshold value of the binarization circuit 29 (see FIG. 8), the frequency at which the gain is 1 is selected from the E (s) / W (s) gain characteristics of FIG.

  The gate circuit 30 is supplied with a focus error signal E (s) including a groove crossing signal. In the gate circuit 30, the band portion of the focus error signal E (s) including the input groove crossing signal is affected by the gain increase of the E (s) / W (s) gain characteristics as shown in FIG. Is masked, and a signal W3 (s) in a band not affected by the gain increase is generated and supplied to the measurement processing block 26 having the same configuration as in FIG.

  In the measurement processing block 26, as shown in FIG. 4, the level of the groove crossing signal W (s) is measured by sampling the signal W3 (s) to obtain a frequency distribution and extracting positive and negative peaks. The measurement processing block 26 enables level measurement in consideration of variations in distribution of maximum and minimum levels.

The block diagram which shows the structural example of the groove crossing signal measurement block of one Embodiment of the groove crossing signal included in the focus error signal in the focus servo circuit of the optical pick-up by this invention. The wave form diagram which shows the signal of each part of the groove crossing signal measurement block of FIG. FIG. 2 is a linear diagram showing frequency (kHz) -voltage (v) characteristics of a frequency detector 21 in the groove crossing signal measurement block of FIG. 1. Explanatory drawing which shows operation | movement of the measurement process block in the groove crossing signal measurement block of FIG. The block diagram which shows the structural example of the groove crossing signal measurement block of other embodiment of the groove crossing signal measurement apparatus contained in the focus error signal in the focus servo circuit of the optical pick-up by this invention. FIG. 6 is a characteristic curve diagram showing closed loop C (s) / R (s) gain characteristics and E (s) / W (s) gain characteristics in a focus servo circuit of an optical pickup of three different types of optical disk reproducing apparatuses. The block diagram which shows the structural example of the groove crossing signal measurement block of further another embodiment of the groove crossing signal measurement apparatus contained in the focus error signal in the focus servo circuit of the optical pick-up by this invention. The wave form diagram which shows the signal of each part of the groove crossing signal measurement block of FIG. The wave form diagram which compares and shows the focus error signal which does not contain a groove crossing signal, and the focus error signal containing a groove crossing signal. FIG. 3 is a block diagram showing an example of a groove crossing signal measuring device included in a focus error signal in a focus servo circuit of an optical pickup in which a general optical disk reproducing device is provided with a groove crossing signal measuring block. FIG. 3 is a block diagram showing a configuration example of a focus servo circuit of an optical pickup of an optical disc reproducing apparatus. FIG. 5 is a waveform diagram showing a tracking error signal TE, an objective lens displacement C (s), and a groove crossing signal W (s) in an example of a focus servo circuit of an optical pickup of three different types of optical disk reproducing apparatuses. The characteristic curve figure which shows the frequency characteristic of the gain and phase of an open loop in an example of the focus servo circuit of the optical pick-up of three different optical disk reproducing | regenerating apparatuses from the same. The characteristic curve figure which shows the frequency characteristic of the gain of an open loop and a closed loop in an example of the focus servo circuit of the optical pick-up of three different optical disk reproducing | regenerating apparatuses from the same.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical disk 2 ... Spindle motor 3 ... Objective lens 4 ... Reflection mirror 5 ... Polarizing beam splitter 6 ... Laser diode 7 ... Condensing lens 8 ... Photoelectric converter 9 ... Differential amplifier 10 ... Phase compensator 11 ... Control part 12 ... Groove crossing signal measurement block 13 ... Subtractor 15 ... Error signal detector 16 ... Low pass filter 17 ... Lead lag filter 18 ... Actuator 20A, 20B, 20C ... Groove crossing signal measuring device 21 ... Frequency detector 22 ... A / D converter DESCRIPTION OF SYMBOLS 23 ... Processing block 24 ... D / A converter 25 ... Gain corrector 26 ... Measurement processing block 27 ... Filter circuit 28 ... High pass filter 29 ... Binarization circuit

Claims (3)

A groove crossing signal that is mixed in the focus error signal due to the influence of the track groove when the reproducing laser beam of the optical pickup crosses a track on the optical disk while the data recorded on the optical disk is being reproduced by the optical pickup. In an optical pickup groove crossing signal measuring device equipped with a measurement processing unit for measuring the level of
A tracking error signal having the same period as the groove crossing signal is supplied, and a frequency detector that detects the frequency of the tracking error signal;
A gain calculation unit that obtains gain data by referring to a preset frequency-gain table based on the detection frequency of the frequency detection unit in a state where only the focus servo is applied;
A gain that is supplied with a focus error signal including the groove crossing signal, corrects the gain with the gain data obtained by the gain calculation unit, and outputs the focus error signal including the corrected groove crossing signal to the measurement processing unit. A correction unit;
An apparatus for measuring a signal across a groove of an optical pickup. A groove crossing signal that is mixed in the focus error signal due to the influence of the track groove when the reproducing laser beam of the optical pickup crosses a track on the optical disk while the data recorded on the optical disk is being reproduced by the optical pickup. In an optical pickup groove crossing signal measuring device equipped with a measurement processing unit for measuring the level of
A focus error signal including the groove crossing signal is supplied, and the filter unit corrects the gain characteristic of the focus error signal / groove crossing signal determined by the transfer characteristic of the focus servo system;
A high-pass filter section that cuts low-frequency fluctuations in the focus error signal including the corrected groove crossing signal;
An apparatus for measuring a signal across a groove of an optical pickup. A groove crossing signal that is mixed in the focus error signal due to the influence of the track groove when the reproduction laser beam of the optical pickup crosses a track on the optical disk while the data recorded on the optical disk is being reproduced by the optical pickup. In an optical pickup groove crossing signal measuring device equipped with a measurement processing unit for measuring the level of
A tracking error signal having the same period as the groove crossing signal is supplied, and a frequency detector that detects the frequency of the tracking error signal;
A binarization circuit unit that is supplied with a detection frequency of the frequency detection unit and executes binarization processing with a threshold value determined in advance from a gain characteristic of a focus error signal / groove crossing signal;
A mask error signal including the groove crossing signal is masked by a signal generated by the binarization process, thereby correcting only the band portion not affected by the gain increase in the focus error signal. A gate circuit unit that outputs a focus error signal including the groove crossing signal to the measurement processing unit;
An apparatus for measuring a signal across a groove of an optical pickup.

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