JP2000030260A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly detect a header, even when the state of a push-pull signal is fluctuated by various factors by generating an optimum reference signal corresponding to an actual push-pull signal in real time. SOLUTION: A peak detecting circuit 12 detects the peak value of a push-pull signal, and this peak value is inputted to a comparator 10 through an LPF 14. The output signal of the LPF 14 is applied to a comparator 10 as a positive reference signal +Ba for detecting header, which is to be compared with the push-pull signal. Meanwhile a bottom detecting circuit 13 detects the bottom value of the push-pull signal, and this bottom value is inputted to a comparator 15 through an LPF 15. The output signal of the LPF 15 is applied to a comparator 11 as a negative reference signal -Ba for detecting header which is to be compared with the push-pull signal. Thus, an optimum reference signal corresponding to the actual push-pull signal is generated in real time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical disk device such as a DVD-RAM drive capable of recording / reproducing data.

[0002]

2. Description of the Related Art A wobble land / groove system is adopted as a physical format of a DVD-RAM. In the wobble land-groove method, as shown in FIGS. 6 and 7, a convex track (groove track) 100 formed on the disk surface is viewed from the side irradiated with the laser beam.
This is a method in which marks are recorded on both tracks of the track 101 and the concave track (land track) 101. A minute undulation called a wobble 102 is formed on a track at a predetermined frequency, and a rough read channel PLL pull-in can be performed based on a frequency signal obtained by detecting the wobble 102. I have.

[0003] A DVD-RAM is provided with a header section 105 arranged so as to cut the land track 101 and the groove track 100. In the header section 105, bits as address information are recorded at the time of manufacture. I have. That is, in the wobble land / groove method, an address can be detected by reading bits of the header section 105.

[0004] In such a wobble land-groove type disk drive, as shown in FIG. 8, among outputs of a four-divided optical detector 122 which receives reflected light from a disk 121 and converts it into an electric signal, Disc 1
The push-pull method of calculating the difference value of the output sum of each of the two photodetectors 122 divided inside and outside in the radial direction with respect to 21 track rows and outputting this as a tracking error signal (push-pull signal) is known. Used in tracking servo. In addition, since the push-pull signal has a unique waveform when the light spot passes through the header, the arrival of the header is detected by detecting this. FIG. 8 shows the configuration of such a conventional header detection circuit.

As shown in FIG. 1, in the conventional header detection circuit, positive and negative values of the push-pull signal output from the push-pull signal generation circuit 123 are fixed by comparators 124 and 125, respectively. And the arrival of the header is detected from the comparison result.

However, in such a header detection circuit, there are differences in the reflectivity of the header portion for each disk, the state of the tracking servo, and further, scratches, dirt,
There is a possibility that erroneous detection of the header portion may occur due to various factors such as deformation, and this has been a problem to be solved in order to provide a highly reliable optical disk device.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem. In an optical disk apparatus for recording or reproducing a disk of a land-groove recording system, a physical sector address on the disk is a pit. It is an object of the present invention to provide an optical disk device capable of detecting a header portion formed by using a push-pull method with high accuracy.

[0008]

According to a first aspect of the present invention, there is provided an optical disk apparatus comprising a pit row indicating a physical sector address, and the pit row being alternately arranged in a radial direction with respect to a track row. A light beam irradiating means for irradiating a light beam on the disk to form a light beam spot in an optical disk apparatus for recording or reproducing a disk of a land-groove recording system having a header portion composed of a plurality of header regions arranged offset. And a plurality of photodetectors that are arranged in the radial direction and receive reflected light of the light beam spot from the disc and convert the reflected light into electric signals, and the plurality of photodetectors that are divided and arranged. A push-pull signal generation circuit for obtaining a difference value between the output signals and outputting the result as a push-pull signal; Comparison means for comparing the push-pull signal output from the pull signal generation circuit with a positive reference signal and a negative reference signal optimally set for each disk, and the header section based on a comparison result of the comparison means And detecting means for detecting

According to a second aspect of the present invention, there is provided an optical disk device comprising a header section formed of a plurality of header areas formed of a pit string indicating a physical sector address and alternately offset in a radial direction with respect to a track string. An optical disk device for recording or reproducing a disk of a land-groove recording system having a light beam irradiating means for irradiating the disk with a light beam to form a light beam spot; A plurality of photodetectors for receiving the reflected light of the beam spot from the disc and converting them into electric signals; and a push-pull for obtaining a difference value between signals respectively output from the plurality of divided photodetectors. A push-pull signal generation circuit for outputting a signal, and a push-pull signal output from the push-pull signal generation circuit. A filter that passes a high-frequency component of the signal, a comparison unit that compares the signal that has passed through the filter with a positive reference signal and a negative reference signal that are optimally set for each disk, and a comparison result of the comparison unit And detecting means for detecting the header section based on

According to a third aspect of the present invention, there is provided an optical disk device comprising a header section formed of a plurality of header areas formed of a pit string indicating a physical sector address and alternately arranged in a radial direction with respect to a track string. An optical disk device for recording or reproducing a disk of a land-groove recording system having a light beam irradiating means for irradiating the disk with a light beam to form a light beam spot; A plurality of photodetectors for receiving the reflected light of the beam spot from the disc and converting them into electric signals; and a push-pull for obtaining a difference value between signals respectively output from the plurality of divided photodetectors. A push-pull signal generation circuit for outputting a signal as a signal, and a pin for detecting a peak value of the output push-pull signal. And a bottom detection circuit that detects a bottom value of the output push-pull signal, and a positive reference signal generation unit that generates a positive reference signal based on the peak value of the detected push-pull signal. ,
Negative reference signal generating means for generating a negative reference signal based on the detected bottom value of the push-pull signal; output of the generated positive reference signal, negative reference signal, and the push-pull signal generation circuit And a detecting means for detecting the header portion based on a result of the comparison by the comparing means. An optical disk device according to a fourth aspect of the present invention is formed of a pit string indicating a physical sector address,
In an optical disc apparatus for recording or reproducing a disc of a land-groove recording system having a header portion composed of a plurality of header areas arranged alternately in a radial direction with respect to a track row, the disc is irradiated with a light beam. A light beam irradiation means for forming a light beam spot; a plurality of photodetectors arranged to be divided in the radial direction and receiving reflected light of the light beam spot from the disk and converting the light beam spot into an electric signal; A push-pull signal generation circuit that obtains a difference value between signals respectively output from the plurality of photodetectors arranged as a push-pull signal, and a component of the header portion output from the push-pull signal generation circuit A first peak detection circuit for detecting a first peak value of the push-pull signal of the push-pull signal; A second peak detection circuit for detecting a second peak value of a push-pull signal of a component other than the header portion output from the component circuit, and a push of the component of the header portion output from the push-pull signal generation circuit A first bottom detection circuit for detecting a first bottom value of the pull signal; and a second bottom detection circuit for detecting a second bottom value of the push-pull signal of a component other than the header portion output from the push-pull signal generation circuit. Bottom detection circuit, a positive reference signal generating means for generating a positive reference signal based on the detected first peak value and second detected peak value, Negative reference signal generating means for generating a negative reference signal based on the bottom value of 2, the generated positive reference signal and negative reference signal, and the output from the push-pull signal generation circuit. Comparing means for comparing the push-pull signal, characterized by comprising a detecting means for detecting the header portion based on a comparison result of the comparing means.

According to a fifth aspect of the present invention, there is provided an optical disk device comprising a header section comprising a plurality of header areas formed of a pit string indicating a physical sector address and alternately arranged in a radial direction with respect to a track string. An optical disk device for recording or reproducing a disk of a land-groove recording system having a light beam irradiating means for irradiating the disk with a light beam to form a light beam spot; A plurality of photodetectors for receiving the reflected light of the beam spot from the disc and converting them into electric signals; and a push-pull for obtaining a difference value between signals respectively output from the plurality of divided photodetectors. A push-pull signal generation circuit for outputting a signal, and a push-pull signal output from the push-pull signal generation circuit. A peak detection circuit that detects a peak value of the signal, a bottom detection circuit that detects a bottom value of the push-pull signal output from the push-pull signal generation circuit, and a peak value holding unit that holds an output of the peak detection circuit. A bottom value holding unit for holding an output of the bottom detection circuit, and an output of the peak detection circuit and an output of the bottom detection circuit to the peak value holding unit and the bottom value holding unit according to a detection cycle of the header unit. Control means for controlling the holding timing; positive reference signal generating means for generating a positive reference signal based on the peak value held by the peak value holding means; and bottom value held by the bottom value holding means Negative reference signal generating means for generating a negative reference signal based on the reference signal, the generated positive reference signal and the negative reference signal, and Comparing means for comparing the push-pull signal outputted from-pull signal generating circuit, characterized by comprising a detecting means for detecting the header portion based on a comparison result of the comparing means.

According to a sixth aspect of the present invention, there is provided an optical disk device comprising a header section formed of a plurality of header areas formed of a pit row indicating a physical sector address and alternately offset in a radial direction with respect to a track row. An optical disk device for recording or reproducing a disk of a land-groove recording system having a light beam irradiating means for irradiating the disk with a light beam to form a light beam spot; A plurality of photodetectors for receiving the reflected light of the beam spot from the disc and converting them into electric signals; and a push-pull for obtaining a difference value between signals respectively output from the plurality of divided photodetectors. A push-pull signal generation circuit for outputting a signal, and a push-pull signal output from the push-pull signal generation circuit. A peak detection circuit that detects a peak value of the signal, a bottom detection circuit that detects a bottom value of the push-pull signal output from the push-pull signal generation circuit, and a peak value holding unit that holds an output of the peak detection circuit. A bottom value holding unit for holding an output of the bottom detection circuit, and an output of the peak detection circuit and an output of the bottom detection circuit to the peak value holding unit and the bottom value holding unit according to a detection cycle of the header unit. Control means for controlling the timing of holding, a first filter for passing a low-frequency component of the output of the peak value holding means, a second filter for passing a low-frequency component of the output of the bottom value holding means, A positive reference signal generating means for generating a positive reference signal based on the signal passed through the first filter; Negative reference signal generating means for generating a negative reference signal based on the generated signal, and comparing the generated positive reference signal and the negative reference signal with the push-pull signal output from the push-pull signal generation circuit. And a detecting means for detecting the header portion based on the comparison result of the comparing means.

According to a seventh aspect of the present invention, there is provided an optical disk apparatus comprising a header section formed of a plurality of header areas formed of a pit row indicating a physical sector address and alternately offset in a radial direction with respect to a track row. An optical disk device for recording or reproducing a disk of a land-groove recording system having a light beam irradiating means for irradiating the disk with a light beam to form a light beam spot; A plurality of photodetectors for receiving the reflected light of the beam spot from the disc and converting them into electric signals; and a push-pull for obtaining a difference value between signals respectively output from the plurality of divided photodetectors. A push-pull signal generation circuit for outputting a signal as a signal, and a pin for detecting a peak value of the output push-pull signal. A first detection circuit, a bottom detection circuit for detecting a bottom value of the output push-pull signal, a first filter for passing a low-frequency component of an output of the peak detection circuit, and a low level of an output of the bottom detection circuit. A second filter that passes a band component, a positive reference signal generating unit that generates a positive reference signal based on the signal that has passed through the first filter, and a signal that has passed through the second filter. Negative reference signal generating means for generating a negative reference signal, and comparing means for comparing the generated positive reference signal and the negative reference signal with the push-pull signal output from the push-pull signal generation circuit, Detecting means for detecting the header portion based on a comparison result of the comparing means.

According to the present invention, since the optimum reference signal corresponding to the actual push-pull signal is generated in real time, the difference in the reflectivity of the header portion of each disk, the state of the tracking servo, and the scratch, dirt, Even if the state of the push-pull signal fluctuates due to various factors such as deformation, it is possible to obtain a reference signal capable of correctly detecting the header.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an optical disk device according to an embodiment of the present invention.

The beam emitted from the laser diode 1 is applied to an information recording surface of a disk 4 rotated by a spindle motor 3 through an objective lens 2. The light reflected from the information recording surface of the disk 4 passes through the objective lens 2 again, is bent by the beam splitter 5, and is guided to the optical detector 6.

The optical detector 6 is formed by dividing a track row on the disk 4 into two in the radial direction and the tangential direction, each of which is divided into four parts. / V amplifier 7. Each voltage generated from each I / V amplifier 7 is introduced to a push-pull signal generation circuit 8, which divides the track row of the disk 4 into an inner side and an outer side in a radial direction. The difference between the output sums of the two photodetectors is obtained, and the two comparators 1 are used as a tracking error signal (push-pull signal) PP.
0, 11 and peak detection circuit 12 and bottom detection circuit 1
3 respectively.

At the subsequent stage of the push-pull signal generation circuit 8, the signal waveform of the header component in the push-pull signal waveforms inputted to the comparators 10, 11 and the peak detection circuit 12 and the bottom detection circuit 13 appears in high quality. As described above, it is desirable to add an HPF (not shown) that allows only the high frequency component of the output signal of the push-pull signal generation circuit 8 to pass.
The present embodiment will now be described with reference to the signal waveform diagram of FIG.

As shown in the figure, the push-pull signal is
During the time when the light spot passes through the header area, the light spot is largely and positively offset in the positive and negative directions. Therefore, it is possible to set the positive and negative reference signals and detect when the push-pull signal exceeds any of the reference signals as the arrival time of the header.

The peak detection circuit 12 detects the peak value of the push-pull signal and outputs a peak detection signal as shown by Pk in FIG.
Enter 0. The output signal of the LPF 14 is applied to the comparator 10 as a header detection positive reference signal + Ba to be compared with the push-pull signal in the comparator 10.

On the other hand, the bottom detection circuit 13 detects the bottom value of the push-pull signal, outputs a bottom detection signal as shown by Bm in FIG. 2, and inputs this to the comparator 11 through the LPF 15. The output signal of the LPF 15 is the comparator 1
At 1, it is added to the comparator 11 as a negative reference signal -Ba for header detection which is compared with the push-pull signal.
This makes it possible to generate an optimum reference signal according to the actual push-pull signal in real time. That is, even if the state of the push-pull signal fluctuates due to various factors such as a difference in the reflectance of the header part of each disk, the state of the tracking servo, and the scratches, dirt, and deformation of the disk, it is necessary to correctly detect the header. The reference signal which can be obtained can be obtained.

Each of the comparators 10 and 11 compares the positive reference signal + Ba generated as described above with the push-pull signal, and compares the negative reference signal -Ba with the push-pull signal. . The comparators 10 and 11 output the header detection pulse to the data processor 21 through the retriggerable multivibrators 16 and 17 during a period in which the absolute value of the push-pull signal is larger than the reference signals + Ba and -Ba.

Retriggerable multivibrators 16, 1
Numeral 7 is for guaranteeing the header detection pulse output from the comparators 10 and 11. Even if the signal of the header component in the push-pull signal is interrupted due to various reasons, a desired pulse waveform of the header detection pulse is obtained. Can be compensated for.

On the other hand, the output of each I / V amplifier 7 is sent to a data reading system circuit separately from the servo system circuit. That is, the output of each I / V amplifier 7 is introduced into an adder 18, added, then equalized in waveform by an equalizer 19, converted into a digital signal clock-normalized by a data strobe circuit 20, and converted into a data processor. 21. The data processor 21 performs ID extraction, frame slipping processing, error correction processing, and the like to generate reproduced data. Further, the data processor 21
The timing necessary for various data processing and the clock for data reproduction are generated using the header detection pulse.

A part of the RF signal output from the adder 18 is input to the data rate detector 22. The data rate detector 22 measures the reading linear velocity that changes every moment from the length of the sign inversion section and the average frequency of the input RF signal, and based on the measured reading linear velocity, the peak detection circuit 12 and the bottom detection circuit 13, LPF14,
15 is optimally controlled. For example, LP
By controlling the time constants of F14 and F15 so as to be optimized in accordance with the linear velocity, a constant header detection accuracy is guaranteed against fluctuations in the linear velocity.

Next, an optical disk device according to a second embodiment of the present invention will be described.

FIG. 3 is a diagram showing the configuration of the optical disk device of this embodiment, and FIG. 4 is a signal waveform diagram showing a reference signal for header detection. In FIGS. 3 and 4, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

This optical disc apparatus detects the first peak value Pk1 of the push-pull signal output from the push-pull signal generation circuit 8, particularly the first peak value Pk1 of the header component (relatively low frequency component) signal. A detection circuit 12a for detecting a second peak value Pk2 of a signal of a component (relatively high frequency component) other than the header portion of the push-pull signal;
And a first bottom detection circuit 13a for detecting a first bottom value Bm1 of a signal of a header part component (relatively low frequency component) among push-pull signals.
A second bottom detection circuit 13b for detecting a second bottom value Bm2 of a signal of a component other than the header portion (relatively high frequency component) of the push-pull signal, and a first peak value Pk1 and a second And a first mixer 31 that generates a positive reference signal + Ba based on the peak value Pk2 of the second and a negative reference signal −Ba based on the detected first bottom value Bm1 and second bottom value Bm2. The second mixer 3 to be generated
2 is provided.

The response speed of each of the peak detection circuits 12a and 12b and each of the bottom detection circuits 13a and 13b is determined so that the peak value or the bottom value of the signal of the target component can be detected.

In this optical disk device, with the above configuration, the positive and negative reference signals + Ba,-for detecting the header are respectively provided.
Ba is generated. That is, the first peak value Pk1 of the signal of the header component and the second peak value Pk2 of the push-pull signal other than the header component are respectively detected, and each of the peak values Pk1 and Pk2 is calculated according to a predetermined calculation formula. Positive reference signal + between Pk1 and Pk2
In addition to setting Ba, a first bottom value Bm1 of the signal of the header component and a second bottom value Bm2 of the push-pull signal other than the header component are respectively detected, and a predetermined calculation formula is obtained from these bottom values Bm1 and Bm2. Therefore, a negative reference signal -Ba is set between the bottom values Bm1 and Bm2.

As a method of obtaining the positive reference signal + Ba from each of the peak values Pk1 and Pk2, simply use each peak value Pk
1, a method of setting an intermediate value of Pk2 to a positive reference signal + Ba,
Each peak value Pk1, Pk2 is weighted uniquely,
The sum of the weighted values is added to the positive reference signal + Ba
And the like. Also, each bottom value Bm1, Bm2
The same applies to the case where the negative reference signal -Ba is obtained from

With this configuration, erroneous detection of low-frequency noise generated in an area other than the header as a header is reduced.

Next, an optical disk device according to a third embodiment of the present invention will be described.

FIG. 5 is a diagram showing the configuration of the optical disk device of this embodiment. In FIG. 5, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. This optical disk device is configured by connecting sample / hold circuits 33 and 34 to the subsequent stages of the peak detection circuit 12 and the bottom detection circuit 13, respectively. The sample / hold timing of each of the sample / hold circuits 33 and 34 is controlled by the data processor 21. That is, the data processor 21 causes the sample / hold circuit 33 to hold the output of the peak detection circuit 12 immediately after the peak detection circuit 12 detects the peak value of the header portion for a certain period of time according to the detected period of the header portion. Similarly, control is performed so that the sample / hold circuit 34 holds the output of the bottom detection circuit 13 immediately after the bottom detection circuit 13 detects the bottom value of the header section for a certain period of time.

The output of each sample / hold circuit 34 becomes positive and negative reference signals + Ba and -Ba through LPFs 14 and 15, respectively, and is input to comparators 10 and 11;
This is compared with the push-pull signal.

With this configuration, erroneous detection of low-frequency noise generated in an area other than the header as a header is reduced.

[0038]

As described above, according to the present invention, in an optical disk apparatus for recording or reproducing a land-groove recording type disk, an optimum reference signal corresponding to an actual push-pull signal is generated in real time. Even if the state of the push-pull signal fluctuates due to various factors such as the difference in reflectivity of the header part of each disk, the tracking servo state, and the scratches, dirt, and deformation of the disk, it is necessary to detect the header correctly. A reference signal that can be obtained can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical disc device according to a first embodiment of the present invention.

FIG. 2 is a signal waveform diagram for describing a method of generating a header detection reference signal in the optical disk device of FIG.

FIG. 3 is a diagram illustrating a configuration of an optical disc device according to a second embodiment of the present invention.

FIG. 4 is a signal waveform diagram for describing a method of generating a header detection reference signal in the optical disk device of FIG. 3;

FIG. 5 is a diagram illustrating a configuration of an optical disc device according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a physical format of a wobble / land-groove optical disk.

FIG. 7 is a diagram showing a configuration of a header section in a physical format of an optical disk of the wobble land groove system.

FIG. 8 is a diagram showing a configuration of a header detection circuit of a conventional optical disk device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laser diode 2 ... Objective lens 3 ... Spindle motor 4 ... Disk 5 ... Beam splitter 6 ... Optical detector 7 ... I / V amplifier 8 ... Push-pull signal Generation circuit 10, 11 ... Comparator 12 ... Peak detection circuit 13 ... Bottom detection circuit 14,15 ... LPF 16,17 ... Retriggerable multivibrator 18 ... Adder 19 ..Equalizer 20 Data strobe circuit 21 Data processor 12a First peak detection circuit 12b Second peak detection circuit 13a First bottom detection circuit 13b Second bottom detection circuit 31 first mixer 32 second mixer 33, 34 sample / hold circuit

Continued on the front page F term (reference) 5D090 AA01 BB04 CC18 DD03 DD05 EE12 EE18 FF15 GG10 HH01 JJ16 5D118 AA14 AA17 AA18 BA01 BB05 BF02 BF03 CB03 CC12 CD11 CF05

Claims (9)

[Claims] 1. A land-groove recording disk having a header portion formed of a plurality of header regions formed of a pit row indicating a physical sector address and alternately offset in a radial direction with respect to a track row is recorded. Or in an optical disc apparatus for reproduction, a light beam irradiating means for irradiating the disc with a light beam to form a light beam spot, and arranged in the radial direction so as to divide the reflected light of the light beam spot from the disc. A plurality of photodetectors that receive and convert the signals into electric signals, and a push-pull signal generation circuit that obtains a difference value between signals output from the plurality of photodetectors divided and arranged and outputs the difference value as a push-pull signal. The push-pull signal output from the push-pull signal generation circuit is optimally set for each disc. Positive reference signal and a negative reference signal and comparing means for comparing each of the optical disk apparatus characterized by comprising a detecting means for detecting the header portion based on a comparison result of the comparing means. 2. A land-groove recording type disc having a header portion formed of a plurality of header areas formed of a pit row indicating a physical sector address and alternately offset in a radial direction with respect to a track row is recorded. Or in an optical disc apparatus for reproduction, a light beam irradiating means for irradiating the disc with a light beam to form a light beam spot, and arranged in the radial direction so as to divide the reflected light of the light beam spot from the disc. A plurality of photodetectors that receive and convert the signals into electric signals, and a push-pull signal generation circuit that obtains a difference value between signals output from the plurality of photodetectors divided and arranged and outputs the difference value as a push-pull signal. A filter that passes a high-frequency component of the push-pull signal output from the push-pull signal generation circuit A comparing unit that compares the signal passed through the filter with a positive reference signal and a negative reference signal that are optimally set for each disk; and a detection unit that detects the header section based on a comparison result of the comparing unit. An optical disk device comprising: 3. A land-groove recording disk formed of a plurality of header areas formed of a pit row indicating a physical sector address and alternately arranged in a radial direction with respect to a track row. Or in an optical disc apparatus for reproduction, a light beam irradiating means for irradiating the disc with a light beam to form a light beam spot, and arranged in the radial direction so as to divide the reflected light of the light beam spot from the disc. A plurality of photodetectors that receive and convert the signals into electric signals, and a push-pull signal generation circuit that obtains a difference value between signals output from the plurality of photodetectors divided and arranged and outputs the difference value as a push-pull signal. A peak detection circuit for detecting a peak value of the output push-pull signal; A bottom detection circuit that detects a bottom value of the pull signal; a positive reference signal generation unit that generates a positive reference signal based on a peak value of the detected push-pull signal; and a bottom of the detected push-pull signal. Negative reference signal generation means for generating a negative reference signal based on the value; comparing the generated positive reference signal and negative reference signal with the push-pull signal output from the push-pull signal generation circuit An optical disc device comprising: comparing means; and detecting means for detecting the header section based on a comparison result of the comparing means. 4. A land-groove recording type disk having a header portion formed of a plurality of header areas formed of a pit row indicating a physical sector address and alternately offset in a radial direction with respect to a track row is recorded. Or in an optical disc apparatus for reproduction, a light beam irradiating means for irradiating the disc with a light beam to form a light beam spot, and arranged in the radial direction so as to divide the reflected light of the light beam spot from the disc. A plurality of photodetectors that receive and convert the signals into electric signals, and a push-pull signal generation circuit that obtains a difference value between signals output from the plurality of photodetectors divided and arranged and outputs the difference value as a push-pull signal. A first pin of the push-pull signal of the component of the header output from the push-pull signal generation circuit; A first peak detection circuit that detects a peak value, a second peak detection circuit that detects a second peak value of a push-pull signal of a component other than the header part output from the push-pull signal generation circuit, A first bottom detection circuit that detects a first bottom value of the push-pull signal of the component of the header output from the push-pull signal generation circuit; and a component other than the header output from the push-pull signal generation circuit A second bottom detection circuit that detects a second bottom value of the push-pull signal of the component (b), and a positive bottom signal that generates a positive reference signal based on the detected first peak value and second peak value. Reference signal generation means; negative reference signal generation means for generating a negative reference signal based on the detected first bottom value and second bottom value; and the generated positive reference signal A comparison means for comparing the signal and the negative reference signal with the push-pull signal output from the push-pull signal generation circuit; and a detection means for detecting the header section based on a comparison result of the comparison means. An optical disc device characterized by the above-mentioned. 5. A land-groove recording disk having a header portion formed of a plurality of header areas formed of a pit row indicating a physical sector address and alternately offset in a radial direction with respect to a track row is recorded. Or in an optical disc apparatus for reproduction, a light beam irradiating means for irradiating the disc with a light beam to form a light beam spot, and arranged in the radial direction so as to divide the reflected light of the light beam spot from the disc. A plurality of photodetectors that receive and convert the signals into electric signals, and a push-pull signal generation circuit that obtains a difference value between signals output from the plurality of photodetectors divided and arranged and outputs the difference value as a push-pull signal. Peak detection for detecting a peak value of the push-pull signal output from the push-pull signal generation circuit Path, a bottom detection circuit for detecting a bottom value of the push-pull signal output from the push-pull signal generation circuit, a peak value holding unit for holding an output of the peak detection circuit, and holding an output of the bottom detection circuit. Control means for controlling the timing of holding the output of the peak detection circuit and the output of the bottom detection circuit in the peak value holding means and the bottom value holding means according to the detection cycle of the header section. A positive reference signal generating unit that generates a positive reference signal based on the peak value held by the peak value holding unit; and a negative reference signal based on the bottom value held by the bottom value holding unit. Negative reference signal generating means, and the generated positive reference signal and negative reference signal and the output from the push-pull signal generation circuit. Optical disc device comprising comparing means for comparing the push-pull signal, by including a detection means for detecting the header portion based on a comparison result of the comparing means has. 6. A land-groove recording disk formed of a plurality of header areas formed of a pit row indicating a physical sector address and alternately arranged in a radial direction with respect to a track row to be recorded. Or in an optical disc apparatus for reproduction, a light beam irradiating means for irradiating the disc with a light beam to form a light beam spot, and arranged in the radial direction so as to divide the reflected light of the light beam spot from the disc. A plurality of photodetectors that receive and convert the signals into electric signals, and a push-pull signal generation circuit that obtains a difference value between signals output from the plurality of photodetectors divided and arranged and outputs the difference value as a push-pull signal. Peak detection for detecting a peak value of the push-pull signal output from the push-pull signal generation circuit Path, a bottom detection circuit for detecting a bottom value of the push-pull signal output from the push-pull signal generation circuit, a peak value holding unit for holding an output of the peak detection circuit, and holding an output of the bottom detection circuit. Control means for controlling the timing of holding the output of the peak detection circuit and the output of the bottom detection circuit in the peak value holding means and the bottom value holding means according to the detection cycle of the header section. A first filter that passes a low-pass component of the output of the peak value holding unit, a second filter that passes a low-pass component of the output of the bottom value holding unit, and a signal that has passed through the first filter A positive reference signal generating means for generating a positive reference signal based on the signal; and a negative reference signal based on the signal passing through the second filter. A negative reference signal generating means, a comparing means for comparing the generated positive reference signal and the negative reference signal with a push-pull signal output from the push-pull signal generating circuit, and a comparison between the comparing means. An optical disk device comprising: a detection unit configured to detect the header portion based on a result. 7. A land-groove recording disk formed of a plurality of header areas each formed of a pit row indicating a physical sector address and alternately arranged in the radial direction with respect to a track row. Or in an optical disc apparatus for reproduction, a light beam irradiating means for irradiating the disc with a light beam to form a light beam spot, and arranged in the radial direction so as to divide the reflected light of the light beam spot from the disc. A plurality of photodetectors that receive and convert the signals into electric signals, and a push-pull signal generation circuit that obtains a difference value between signals output from the plurality of photodetectors divided and arranged and outputs the difference value as a push-pull signal. A peak detection circuit for detecting a peak value of the output push-pull signal; A bottom detection circuit for detecting a bottom value of the pull signals, first passing the low-frequency component of the output of the peak detecting circuit 1
And a second filter that passes a low-frequency component of the output of the bottom detection circuit.
, A positive reference signal generating means for generating a positive reference signal based on the signal passed through the first filter, and a negative reference signal based on the signal passed through the second filter Negative reference signal generation means; comparison means for comparing the generated positive reference signal and negative reference signal with a push-pull signal output from the push-pull signal generation circuit; and a comparison result of the comparison means. An optical disk device comprising: a detection unit that detects the header portion based on the information. 8. The optical disk device according to claim 1, further comprising a retriggerable multivibrator for guaranteeing a header detection signal output from said comparing means for a predetermined time. 9. The optical disk device according to claim 6, further comprising means for varying a time constant of said first filter and said second filter according to a linear velocity of rotation of said disk. Optical disk device.