JP2002216363A - Optical disk device and information reading method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To accurately detect whether recording is performed on a correct track and to improve the reliability at the time of recording. SOLUTION: A track is formed between the tracks,
What is claimed is: 1. An optical disk device for reading address information from an optical disk having an inter-track portion on which address information is recorded, comprising: an optical head for irradiating a laser beam to the optical disk, wherein a first detector and a second detector are arranged in a track direction. And an optical head provided with a detector for detecting the reflected light from the optical disk and outputting a detection signal, and at a position where the address information is recorded, the first and second detection signals are detected. An adjustment circuit that adjusts and outputs the amplitude; a differential operation circuit that outputs a differential signal that is a difference between the adjusted first and second detection signals; and an address circuit that detects address information based on the differential signal. Provided is an optical disk device or the like including an address detection circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recording and reproduction of signals recorded on a digital disk.

[0002]

2. Description of the Related Art DVD-R / RW is one format of an optical disk for recording / reproducing information. The first feature of this format is that, in order to enhance the compatibility with the DVD-ROM format, address information necessary for specifying an address when recording and reproducing information is formed on a land portion of a disc. That is being done.
A track is an area of an optical disc on which information to be recorded / reproduced is recorded as a mark. The address information is formed in a portion (also referred to as a land) between guide grooves (also referred to as a groove) of a disc for recording / reproducing information.
This address is also called "land pre-pit address" or "LPP address". At the time of following the recording track, the tracking detector of the device detects the incident light and generates a plurality of light amount signals. The address information is
Detection is performed based on a differential signal obtained by taking a difference between a plurality of light quantity signals. Subsequently, a second feature of the above-mentioned format is that a wobble is provided on the optical disc, in which the guide groove is swung in the radial direction at a constant frequency. A wobble signal obtained based on the wobble is used as a reference signal for generating a clock for recording and reproducing information. Like the detection of the address information, the wobble is also detected based on a differential signal obtained by taking a difference between a plurality of light amount signals.

[0003] The configuration and operation of a conventional optical disk device will be described below with reference to FIGS. 8 and 9.

FIG. 8 shows a DVD-R / RW disc 101.
1 is a block diagram of a conventional optical disk device 80 for recording and reproducing information. The optical disc apparatus 80 includes a disc motor 102, an optical head 103 having a tracking detector, a focus detector, and a reproduction signal detector for detecting light, and a focus error signal, a tracking error signal, and a A servo signal / reproduction signal generation circuit 104 for generating a reproduction signal; a focus / tracking control unit 105 for causing an optical head to follow a guide groove of the optical disk 101 using an output signal of the servo signal / reproduction signal generation circuit 104; A differential amplifier circuit 106 for generating a wobble signal / land pre-pit address signal from a light amount signal of a tracking detector of a head, a band-pass filter 107 for extracting a wobble signal component from an output signal of the differential amplifier circuit, A wobble signal binarization circuit 108 for binarizing a wobble signal which is an output signal of the band-pass filter, and a wobble for generating a clock necessary for performing recording / reproduction of the same disc from the wobble binarized signal And a PLL circuit 109.

Further, the optical disk device 80 includes an amplitude detection circuit 110 for detecting the amplitude of the wobble signal extracted by the band pass filter 107, a bias generation circuit 111 for generating a bias voltage, and an output signal of the differential amplification circuit 107. A low-pass component extraction low-pass filter 112 for detecting a land pre-pit address from the ground pre-pit address; and a voltage obtained by adding the voltage generated by the bias generation circuit and the amplitude signal of the wobble signal to a comparison level. , A land pre-pit address detection circuit 114 for detecting a land pre-pit address from the land pre-pit binary signal detected by the land pre-pit detection circuit 113, and the servo signal / Reproduction signal generation circuit 1
04, a reproduced signal binarizing circuit 115 for binarizing the reproduced signal, and a data reproducing PL for generating a clock for demodulating an output signal of the reproduced signal binarizing circuit 115.
An L circuit 116, a demodulation circuit 117 for demodulating using the clock and data generated by the data reproduction PLL circuit, and adding a correction code to user data through an interface of a personal computer or the like connected to the device, and vice versa. At the time of data reproduction, an error correction / addition circuit 118 that corrects demodulated data using a correction code, and sends the data with the error correction code added to the modulation circuit or sends data from the demodulation circuit to the error correction / addition circuit. And a modulation / demodulation control circuit 119 for controlling the modulation / demodulation circuit.

Further, the optical disk device 80 includes a modulation circuit 120 for modulating the user data to which the correction code has been added.
A laser drive waveform generation circuit 121 for generating a laser drive waveform from an output signal of the modulation circuit; a laser drive circuit 122 for driving the laser; and a timing signal required for recording / reproducing data. And a CPU 124 for controlling the entire device.

Next, referring to FIG.
Will be described. First, binarization of a land pre-pit address at the time of information reproduction will be described. FIG. 9 is a diagram showing a waveform of an output signal from the tracking detector when the optical disk device 80 (FIG. 8) follows the guide groove of the DVD-R / RW format disk. Waveforms at the time of tracking of an unrecorded track are shown in FIGS.
Is shown by the waveform on the left. It is assumed that the optical head 103 (FIG. 8) of the optical disk device 80 includes two tracking detectors A and B (for example, see FIG. 2).
Since the tracks on the disk are modulated in the radial direction, the amount of light incident on the detector repeatedly increases and decreases at a constant frequency by the modulation. Further, a pulse-like detection signal is observed at a certain position of the modulation signal according to the address information (land pre-pit information) recorded on the land portion.

The differential amplifier circuit 106 of the optical disk device 80
(FIG. 8) generates a differential signal of the signals of (a) and (b) of FIG. An LPF 112 for removing noise of a high-frequency component or reducing a recording signal at the time of recording is further used as the differential signal.
(FIG. 8). As a result, the signal shown in FIG. 9C is obtained. The detection level for detecting the land pre-pit address signal includes the signal amplitude voltage of the wobble signal extracted by the band-pass filter 107 (FIG. 8) detected by the amplitude detection circuit 110 (FIG. 8) and the bias generation circuit 1
11 (FIG. 8) plus the constant voltage generated is adopted. FIG. 9F shows a waveform of the obtained land pre-pit binary signal. The LPP address detection circuit 114 demodulates and detects a land pre-pit address based on a land pre-pit address signal, a wobble binary signal, and a clock signal generated by the wobble PLL.

Referring to FIG. 9, the operation of the optical disk device 80 (FIG. 8) for recording information will be described. Waveforms at the time of information recording are shown by waveforms on the right side of (a) to (f) of FIG. The optical disc device 80 has a function of converting a current flowing through the tracking detector into a voltage in order to prevent the circuit from being saturated even at a high recording power at the time of recording. Signal detection is performed with a small gain.

When recording information, the optical head 103
The tracking detector shown in FIG. 8 detects a recording signal. More specifically, the optical head 103 (FIG. 8) does not detect the modulation signal of the wobble and the LPP address signal itself, but detects the modulation signal of the wobble mixed with the recording signal and the LPP address. FIGS. 9A and 9B (at the time of recording) show light amount signals detected by the tracking detectors A and B. The differential amplifier circuit 106 (FIG. 8) of the optical disk device 80 generates a differential signal of the signals shown in FIGS. 9A and 9B during recording as well as during reproduction. FIG. 9C shows a signal waveform that has passed through the LPF 112 (FIG. 8). LPF112 (FIG. 8)
Is provided to reduce mixing of recording signals.
However, as shown in FIG. 9C, it is understood that the signal waveform after passing through the LPF 112 (FIG. 8) is still affected by the mixed recording signal.

At the time of recording, the detection level of the land pre-pit is determined so as to detect the land pre-pit address. As shown by the dotted line in FIG. 9C, the detection level is set substantially equal to the maximum amplitude level of the signal waveform in which the recording signal is mixed. However, in this case, many pseudo pulses are detected in the land pre-pit binary signal (FIG. 9 (f)). As a result, LP
The detection rate of the LPP address in the P address detection circuit 114 (FIG. 8) decreases. It should be noted that even if the detection level is increased to avoid erroneous detection, the detection rate of the land pre-pit address decreases. The reason is that a land pre-pit address may not be detected in a low power portion when recording power modulation is performed.

Further, in this detection method, the differential signal of the signal detected by the tracking detector of the optical head 103 (FIG. 8) is used to detect the LPP address. The detection rate of the address fluctuates greatly. This is because the amount of light reflected off the optical disk 101 (FIG. 8) at the time of recording by the off-track and returning to the tracking detector becomes unbalanced, and the state of the differential signal greatly changes.

A third feature of the above-mentioned format is that an information signal can be additionally recorded. According to this format, data can be additionally recorded by specifying a recording start position by a process called linking from the last portion where information recording has been performed. The conventional optical disk device 80 (FIG. 8) uses a tracking error signal to
Track skipping during recording was detected. The reason is that the address detection rate at the time of recording is low, and the risk of recording at another address due to track skipping or the like is avoided. However, when the track jump of the optical head is detected based on the tracking error signal, a large error signal may be detected due to the eccentricity of the disk or the like, and there is a risk of erroneous detection. In order to avoid this erroneous detection, it is necessary to set a higher comparison level with the tracking error signal for determining that the track is skipped. In order to correctly detect the track jump, it is necessary to increase the address detection rate. is important.

[0014]

In the conventional optical disk device 80 (FIG. 8), the LPP address detection rate during recording or during reproduction of a recorded track is reduced, so that the device performs recording on the correct track. The only way to detect this is to mainly detect the tracking error signal, and particularly the reliability at the time of recording was low.

Further, depending on the off-track state of the optical head, there is a problem that the LPP address detection rate further decreases.

An object of the present invention is to provide an optical disk apparatus which accurately detects whether recording is performed on a correct track and improves the reliability at the time of recording.

[0017]

According to the present invention, a differential amplifier for detecting a wobble and a differential amplifier for detecting an LPP address are separately provided. Thus, the LPP address can be detected at a high detection rate by adjusting the balance of the differential amplifier for detecting the LPP address according to the recording / reproducing state of the apparatus. Further, since the differential balance for wobble detection is adjusted by observing the jitter amount of the wobble signal, a high-quality wobble signal can be detected.

More specifically, the optical disk device of the present invention has a structure in which information is recorded, for example, a groove track,
An optical disk device for reading address information from an optical disk having land tracks formed with the groove information and address information specifying a position, wherein the optical head irradiates a laser to the optical disk. An optical head having a tracking detector divided in the track direction into a first detector and a second detector, each of which detects a reflected light from the optical disc and outputs a detection signal; A first detection signal output by a first detector and the second detection signal;
And the second detection signal output by the detector of
At the position where the address information is recorded, the first
And a second detection signal. The first detection signal adjusted by the address detection balance adjustment circuit, the first detection signal adjusted by the address detection balance adjustment circuit, and the second detection signal. An address detection differential operation circuit that outputs an address detection differential signal that is a difference between the two detection signals, and the address information is detected based on the address detection differential signal output from the address detection differential operation circuit. An address detection circuit. This achieves the above object.

The optical disk device further includes an amplitude detection circuit for detecting the amplitudes of the first detection signal and the second detection signal, and the address detection balance adjustment circuit detects the first detection signal detected by the amplitude detection circuit. The amplitude of the first detection signal and the amplitude level of the second detection signal are adjusted to be substantially equal based on the amplitude of the detection signal and the amplitude of the second detection signal, You may output each.

The optical disk apparatus further includes a detection unit for detecting the read rate of the address information, and the address detection balance adjustment circuit controls the first detection so as to maximize the read rate detected by the control unit. The amplitude of the signal and the second detection signal may be adjusted.

The optical disk has wobbles formed at a predetermined period in a radial direction for controlling rotation, and the optical disk device transmits the first detection signal and the second detection signal to each other. The wobble detection balance adjustment circuit receives and adjusts the signal level of the first detection signal and the signal level of the second detection signal by a wobble detection balance adjustment circuit so as to be substantially equal. A wobble detection differential operation circuit that outputs a wobble detection differential signal that is a difference between a first detection signal and the second detection signal, and the wobble detection differential signal output from the wobble detection differential operation circuit And a wobble signal detection circuit for detecting the wobble based on

The wobble detection balance adjustment circuit adjusts the signal level of the first detection signal and the signal level of the second detection signal based on the amount of jitter of the wobble detected by the wobble signal detection circuit. Then, the jitter amount may be minimized.

The optical disk device further includes a detecting unit for detecting the read rate of the address information, and the wobble detecting balance adjusting circuit sets the first read rate so as to maximize the read rate detected by the detecting unit. The signal level of the detection signal and the signal level of the second detection signal may be adjusted.

[0024] The optical disk device may further include a gain control circuit for making the amplitudes of the first detection signal and the second detection signal constant.

According to the information reading method of the present invention, the address information is read from an optical disk having a track on which information is recorded and an inter-track portion formed between the tracks and recording address information for specifying a position. Irradiating the optical disk with a laser, and detecting a reflected signal from the optical disk by each of a first detector and a second detector divided in the track direction to generate a detection signal. Outputting, receiving a first detection signal output by the first detector and a second detection signal output by the second detector, and detecting the first detection signal at a position where the address information is recorded. Adjusting the amplitudes of the detection signal and the second detection signal and outputting the respective signals; and And a step of outputting an address detection differential signal that is a difference between the second detection signal and the second detection signal; and detecting the address information based on the output address detection differential signal. . Thereby, the above object can be achieved.

Hereinafter, the operation will be described.

According to a first aspect of the present invention, the first detection signal output by the first detector and the second detection signal output by the second detector are recorded with address information (LPP address information). The input balance to the address detection differential operation circuit is adjusted using an address detection balance adjustment circuit that adjusts the amplitude of the signal detected by the tracking detector at the position. As a result, at the recording position of the LPP address information, the mixing of the recorded information signal or the recording signal at the time of device recording can be minimized, and the detection rate of the LPP address information can be increased regardless of the recording / reproducing state of the device. it can.

According to a second aspect of the present invention, in the optical disk device of the first aspect, the mixing rate of the information signal recorded at the recording position of the LPP address signal or the recording signal at the time of device recording is minimized to increase the LPP address detection rate. And a specific configuration for balance adjustment of the address detection balance adjustment circuit.

According to a third aspect of the present invention, there is provided another specific configuration for adjusting the balance of the address detection balance adjustment circuit for increasing the LPP address detection rate in the first optical disk device.

According to a fourth aspect of the present invention, the guide groove of the disk is modulated in the radial direction at a frequency serving as a clock reference signal required for reproducing / recording information, and a wobble detection difference for detecting the modulated signal is provided. By separately providing the dynamic operation circuit and the differential operation circuit for detecting the LPP address, the wobble signal and the LPP address signal can be ideally detected.

According to a fifth aspect, in the optical disc apparatus of the fourth aspect, the wobble detection balance adjustment circuit adjusts the signal balance so as to minimize the jitter of the wobble signal.

According to a sixth aspect of the present invention, there is provided the optical disk apparatus according to the fourth aspect of the present invention, wherein a specific configuration is provided in which the balance adjustment of the wobble detection balance adjustment circuit is adjusted from a land pre-pit reading rate (detection rate). is there.

According to the seventh aspect of the present invention, by adding an AGC circuit, the read margin of the LPP address can be expanded against disturbance factors such as defocus, off-track, and tilt of the optical head or disk. .

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing an optical disk recording / reproducing apparatus 10 according to the present embodiment.
Hereinafter, each component of the optical disk recording / reproducing apparatus 10 will be described. The optical disc recording / reproducing apparatus 10 is an optical disc (for example, DVD) on which data to be recorded / reproduced is recorded.
(R / RW disc) 201 for recording and reproducing information.
The optical disk recording / reproducing device 10 includes a disk motor 202
An optical head 203 having a tracking detector, a focus detector, and a reproduction signal detector for detecting light, and a servo signal / reproduction signal for generating a focus error signal, a tracking error signal, and a reproduction signal from light amount signals of various detectors. Generation circuit 204
And a focus / tracking control unit 205 for causing the optical head to follow the guide groove of the optical disk 201 using the output signal of the servo signal / reproduction signal generation circuit 204 and a wobble signal from the output signal of the wobble detection balance adjustment circuit 225. Amplification circuit 206, a band-pass filter (BPF) 207 for extracting a wobble signal component from an output signal of the differential amplification circuit, and a wobble signal 2 for binarizing a wobble signal which is an output signal of the band-pass filter. It includes a value conversion circuit 208 and a wobble PLL circuit 209 for generating a clock necessary for recording / reproducing the same disk from the wobble binary signal.

Further, the optical disk recording / reproducing apparatus 10 comprises:
An amplitude detection circuit 210 for detecting the amplitude of the wobble signal extracted by the bandpass filter 207, a bias generation circuit 211 for generating a bias voltage, and a land prepit address from an output signal of the LPP detection differential amplifier circuit 227. The output of the low-pass filter 212 is binarized using a low-pass filter (LPF) 212 for extracting a low-frequency component and a voltage obtained by adding a voltage generated by the bias generation circuit 211 and an amplitude signal of the wobble signal as a comparison reference level. A land prepit detection circuit 213 for detecting a land prepit address signal, and a land prepit address detection for detecting a land prepit address from a land prepit address signal (binary signal) detected by the land prepit detection circuit 213 A circuit 214;
A reproduction signal binarization circuit 215 for detecting the presence or absence of a recording signal from the reproduction signal generated by the servo signal / reproduction signal generation circuit 204 and reproducing and binarizing the recorded information signal; and a reproduction signal binarization circuit A data reproduction PLL circuit 216 for generating a clock for demodulating the output signal of the output signal 215, a demodulation circuit 217 for demodulating using the clock and data generated by the data reproduction PLL circuit 216, and a personal computer connected to the device And an error correction / addition circuit 218 for adding a correction code to the user's recording data through an interface such as the above, and for correcting the demodulated data at the time of data reproduction using the correction code, and a modulation circuit for adding the error correction code to the data. Or the data from the demodulation circuit to the error correction / addition circuit, and the control of the modulation / demodulation circuit. Further comprising a modem control circuit 219 for performing.

The optical disk recording / reproducing apparatus 10 further comprises a modulation circuit 2 for modulating the user data to which the correction code has been added.
20, a laser drive waveform generation circuit 221 for generating a laser drive waveform from the output signal of the modulation circuit 220, a laser drive circuit 222 for driving the laser,
A gate signal generation circuit 223 for generating a timing signal necessary for reproduction, and a CPU 2 for controlling the entire apparatus
24, a wobble detection balance adjustment circuit 225 for performing balance adjustment of a signal input to the wobble detection differential amplifier circuit 206, an LPP detection differential amplifier circuit 227, and an LPP
An LPP detection balance adjustment circuit 226 for performing balance adjustment of signals input to the detection differential amplifier circuit 227, and an amplitude detection circuit by switching signals input to the wobble detection differential amplifier circuit 206 and the LPP detection differential amplifier circuit 227. And an amplitude detection circuit for detecting the upper / lower envelope of the output signal of the signal changeover switch 228, holding the amplitude information at the timing from the gate signal generator, and outputting it to the CPU 224. 2
29 and an automatic gain control circuit (A) that controls the gain to keep the signal amplitude of the high frequency component of the light amount signal detected by the tracking detector (FIG. 2) of the optical head 203 constant.
(GC circuit) 230. AGC circuit 230
Is effective for instability of address detection due to the off-track state of the optical head, and minimizes the light quantity fluctuation due to off-track. However, the AGC circuit 230 operates based on the presence or absence of a recording signal detected by the reproduction signal binarization circuit 215, and operates as a fixed gain amplifier in an unrecorded track portion. Note that, more simply, the amplitude detection circuit 229 has a function of detecting the amplitude at a specific phase position of the wobble in which the LPP address is recorded.

Before describing the operation of the optical disk recording / reproducing apparatus 10, an optical disk 201 assumed in the present invention will be described. FIG. 2 is a diagram showing the groove shape of the disk. In the disk 201, lands are formed between grooves. Land pre-pits are formed on the lands, and recording marks are formed on the grooves. The waviness in the radial direction of the groove, which is a recording groove, is referred to as wobble in this specification, and is used to detect the linear velocity of the disk. That is, in this specification, generation of a recording clock and CL
Wobble is used for V (Constant Linear Velocity) control. In the drawing, the radial direction indicates a normal direction of a line substantially parallel to the land or the groove. In a DVD-R disc or a DVD-RW disc, the wobble cycle is 186 times the recording clock cycle. The land pre-pits are used to detect the correct position on the disk in addition to the encoded address information.

FIG. 2 further shows a tracking detector 203a provided on the optical head 203. The tracking detector 203a is divided into two along a track (track direction) by a dividing line 203b.
It is divided into two tracking detectors A and B. In other words, there are two detectors A and B along the circumferential direction of the optical disc 201. The two detectors A and B respectively detect and output the amounts of laser light emitted from the optical head 203 and reflected by the optical disk 201. Detectors A and B
Is subjected to a predetermined process and then output to the differential amplifier 206 for wobble detection or the differential amplifier 2 for LPP detection.
27 and is converted into a differential signal representing the difference and used. Note that the tracking detector 203a
It may be divided into a larger number (for example, four or six) of detectors. In such a case, a set of two detectors divided along the division line along the track may be regarded as the two detectors A and B described above.

The present invention is characterized by a differential amplifier 227 for detecting an LPP address and a differential amplifier 2 for detecting a wobble.
06 is provided separately. The grounds are as follows.

In the DVD-R / RW format, as described above, the guide groove for recording information is formed by wobbling. Looking locally, the optical head 203
Is displaced from the track center at a constant frequency with respect to the track. Therefore, the amount of light incident on the tracking detector during information recording causes imbalance, and the recording signal is mixed into the address signal.

Conventionally, the differential balance has been adjusted so that the average amount of light is equally incident on the two tracking detectors. In this differential balance, wobble can be detected by using the center of the amplitude of the differential output. However, it was difficult to detect land pre-pits. The reason is that the land prepit is recorded at a position where the optical head is relatively off-track due to the wobble process, so that the recording signal becomes maximum at the recording position (FIG. 9 (c)).
This is because the land pre-pit cannot be specified (see the waveform at the time of recording in FIG. 9F).

Therefore, if the recording signal is detected by the amplitude detection circuit at the recording position of the land prepit and the two differential balance outputs are adjusted to be equal, the mixing amount is minimized at the recording position of the land prepit. Can be adjusted. That is, the land pre-pit detection rate can be increased.

With the differential balance output adjusted in this way, jitter increases in the wobble signal after binarization, which is not appropriate for binarization of wobble. The binarization of the wobble will be described. The binarization of the wobble is performed by binarizing the wobble signal after passing through the band-pass filter at a constant slice level, or when the duty ratio of the signal after the binarization is changed. It is common to employ a duty feedback slicing method such as 50%. However, regardless of which method is adopted, if binarization is performed near the center of the amplitude of the wobble signal after output of the bandpass filter, jitter increases in the wobble signal after binarization. The reason is that in the differential balance output for increasing the detection rate of the land pre-pit, the mixing of the recording signal at the recording position of the land pre-pit is minimized, but the mixing of the recording signal near the slice level of the wobble signal is reversed. Because the amount increases.

Considering the above results, it can be said that the optimum adjustment point differs between the differential balance adjustment for wobble detection and the differential balance adjustment for land pre-pit detection.

Therefore, the optical disk recording / reproducing apparatus 10
A wobble detection balance adjustment circuit 225 for adjusting the outputs of the two detectors for wobble detection and an LPP detection balance adjustment circuit 226 for adjusting the land prepit detection are separately provided. As a result, two differential amplifiers, that is, a differential amplifier 206 for detecting a wobble signal and a differential amplifier 227 for detecting an LPP, which output differential signals of two outputs of the balance adjustment circuits 225 and 226, are separately provided.
With this configuration, both the wobble signal and the land pre-pit can be accurately detected, and a highly reliable optical disk recording / reproducing apparatus can be obtained. In addition to the provision of the two differential amplifiers, an AGC circuit 230 and an amplitude detection circuit 229 are newly provided. The description of these functions will be described later.

Hereinafter, the operation of the optical disk recording / reproducing apparatus 10 will be described with reference to FIG. 3 (a) to 3 (h) show the waveforms of the respective parts when the optical disc recording / reproducing apparatus 10 reproduces an unrecorded track. In addition, the waveforms on the right side of (a) to (h) of FIG.

Hereinafter, description will be made with reference to the waveforms on the left side of FIGS. FIGS. 3A and 3B are diagrams showing output signals of the LPP detection balance adjustment circuit 226 (FIG. 1) output based on the incident light amount signals from the tracking detectors A and B (FIG. 2). is there. Since the tracking detectors A and B (FIG. 2) detect the same light in the spot shape, their outputs have a relationship that if one light quantity increases, the other light quantity decreases. Although the detection levels are different, all detectors detect land prepits. FIG. 3C shows an amplitude detection timing signal. The section in which the amplitude detection timing signal is "1" is a sampling section, and the section in which "0" is a hold section. The detected signal amplitude is connected to the A / D input of the CPU 224 (FIG. 1). CPU 224 (FIG. 1)
Reads the signal amplitude value at a specific phase position of the wobble where the LPP address is recorded.

The amplitude detection circuit 229 (FIG. 1) includes a peak / bottom detection circuit having a time constant such that the upper and lower envelopes of the input signal can be detected even when the recording signal is superimposed, and an LPP address. , And a low-pass filter (LPF) for detecting and smoothing the modulation component due to the wobble, and a sample-and-hold circuit for sampling and holding the output of the low-pass filter. In FIG. 1, the low-pass filter and the sample-and-hold circuit are provided in the amplitude detection circuit 229 and are not shown.

The CPU 224 (FIG. 1), which detects the amplitude near the position where the LPP address is formed by the output of the amplitude detection circuit 229 (FIG. 1), makes the LPP balance so that the amplitude level of the signal at that position becomes equal. The balance of the adjustment circuit 226 (FIG. 1) is changed. FIG. 3 (a)
In (b), the adjustment is performed so that the high-frequency signal components indicated by the levels between the upper and lower envelopes of the input signal become equal. However, when reproducing an unrecorded track, it is detected as almost zero. Note that more detailed processing will be described in the processing at the time of recording.

FIG. 3D shows a signal generated by the LPP detection differential amplifier circuit 227 (FIG. 1).
12 shows a differential signal that has passed through FIG. The detection level for detecting the land pre-pit address signal is determined by detecting the signal amplitude of the wobble signal extracted by the band-pass filter 207 by the amplitude detection circuit 210, and applying a certain fixed voltage generated by the bias generation circuit 211 to the amplitude voltage. The voltage level obtained by adding the voltage value is adopted (FIG. 3D), and a land pre-pit binary signal (FIG. 3E) is obtained. The LPP address detection circuit 214 outputs a land pre-pit address signal,
The wobble binarized signal ((k) in FIG. 3) and the wobble PL
Based on the clock signal generated at L, demodulation and detection of the land pre-pit address are performed. Wobble 2
The value conversion will be described later.

The waveforms on the right side of FIGS. 3 (a) to 3 (h) show the waveforms of various parts during recording by the optical disk recording / reproducing apparatus 10. Similarly to the reproduction, the balance is adjusted at the time of recording so that the two output signals of the LPP detection balance adjustment circuit 226 (FIG. 1) have the same amplitude level detected from the upper / lower envelope. . The amplitude level is
The same is made at a specific phase position of the wobble signal where the LPP address signal is recorded. FIG. 4 is a diagram showing two output signals of the LPP detection balance adjustment circuit 226 (FIG. 1). The CPU 224 (FIG. 1) adjusts the amplitude levels so that the amplitude levels a and b detected from the upper / lower envelopes are equal.

Description will be made with reference to FIGS. 3A and 3B again. FIGS. 3A and 3B show output signals of the LPP detection balance adjustment circuit 226 (FIG. 1) based on input signals from the two tracking detectors A and B (FIG. 2). FIG. 3D shows the state after the output signal of the LPP detection balance adjustment circuit 226 (FIG. 1) passes through the LPP detection differential amplifier circuit 227 (FIG. 1) and the low-pass filter 212 (FIG. 1). 3 shows the waveforms of FIG. FIG.
(D), the LPP detection differential amplifier 2
It can be seen that the balance of the signal input to 27 (FIG. 1) is adjusted to equalize the signal amplitude near the LPP address signal. Further, in a portion where the phase of the wobble signal is shifted by 180 degrees (a valley portion of the signal), the mixing of the recording signal becomes maximum. As a result, the mixing component of the recording signal is minimized near the LPP address signal, so that the LPP address signal can be reliably detected using the LPP detection level indicated by the dotted line. Therefore, the address detection rate can be dramatically increased.

Next, detection of a wobble signal will be described. The balance adjustment of the differential amplifier for detecting the wobble signal is performed so that the light amounts input to the two tracking detectors are substantially equal. First, the CPU 224 (FIG. 1)
At the time of recording / reproduction, the amplitude is detected by the amplitude detection circuit 229 (FIG. 1), and the balance is adjusted so that the amplitude value (signal level) becomes equal. Then, two signals are input to the wobble detection differential amplifier circuit 206 (FIG. 1). At this time,
The signal changeover switch 228 (FIG. 1) outputs the output of the wobble detection balance adjustment circuit 225 (FIG. 1) to the amplitude detection circuit 2
29 (FIG. 1). As a result, the amplitude detection circuit 229 (FIG. 1) detects the amplitude. At this time, the gate signal generation circuit 223 (FIG. 1) always outputs the detection timing signal so that the average light amount is detected.
The CPU performs amplitude detection an arbitrary number of times, performs averaging processing and the like, and adjusts the signal balance so that the amplitude values become equal.

FIGS. 3F and 3G show the output (solid line) of the wobble detection balance adjustment circuit 225 (FIG. 1),
The amplitude level (dotted line) detected by the CPU 224 (FIG. 1) performing the amplitude averaging process. CPU 224 (FIG. 1)
Is the amplitude value (signal level) obtained by the averaging process shown by the dotted line
, The output of the wobble detection balance adjustment circuit 225 (FIG. 1) is adjusted. By this balance adjustment, the average of the light amounts detected by the respective detectors is almost equalized. As a result, the mixing of the recording signal at the time of recording is minimized near the center of the wobble signal amplitude close to the wobble binarization level. FIG. 3H shows a sample-and-hold signal.
This sample and hold signal is always a high level signal.

FIG. 3 (i) shows the output signal of the wobble detection differential amplifier circuit 206 (FIG. 1) at the time of reproduction / recording after the adjustment. This output signal is further passed through a bandpass filter 2
07 (FIG. 1), a wobble signal component is extracted.
The wobble signal binarization circuit 208 performs binarization. FIG. 3 (j) shows the output signal waveform of the bandpass filter, and FIG. 3 (k) shows the binarized signal.

The signal-to-noise ratio of the wobble signal (S
/ N ratio) is relatively good, it is considered that the increase of the jitter is not remarkable.
7 may be directly input to the bandpass filter 208. In this case, the wobble detection balance adjustment 225
Also, since the components of the wobble detection differential amplifier 206 can be omitted, the circuit configuration can be simplified as compared with the configuration of FIG.

In the description so far, the operation of reproducing an unrecorded track and the operation of recording information have been described. Next, with reference to FIG. 5, an operation of reproducing the recording track by the optical disk recording / reproducing apparatus 10 (FIG. 1) will be described. The operation of reproducing a recording track is basically the same as the operation of recording information. When the LPP detection balance adjustment circuit 226 (FIG. 1) is adjusted, the signal changeover switch 228 (FIG. 1) operates so that the output of the LPP detection balance adjustment circuit 226 (FIG. 1) is input to the amplitude detection circuit 229 (FIG. 1). Switch to At this time, the gate signal generation circuit 223 (FIG. 1) generates a sample and hold pulse so as to detect the amplitude near the LPP address recording position.

The CPU 224, based on the output signal of the amplitude detection circuit 229 (FIG. 1), (a) and (b) of FIG.
The LPP detection differential balance adjustment circuit 226 (FIG. 1) is adjusted so that the amplitude levels between the upper and lower envelopes of the input signal shown in FIG. Next, when adjusting the wobble signal detection differential balance adjustment circuit, the signal changeover switch 2
28 (FIG. 1) switches so that the output of the balance adjustment circuit is input to the amplitude detection circuit 229 (FIG. 1).
The gate signal generation circuit 223 (FIG. 1) sets the output signal to “1” in order to detect the average light amount. The CPU 224 (FIG. 1) performs amplitude detection and averaging processing, and adjusts the signal balance based on the obtained amplitude values so that the amplitudes become equal.

The differential balance for detecting the LPP is adjusted so that the amplitude of the high-frequency signal component near the recording position of the LPP address signal becomes equal during reproduction. However, this adjustment position is different from the adjustment position at the time of recording. The reason is,
At the time of recording, the power of the laser, which is the light source of the optical head 203, has a high output, and this modulated light is reflected by the disk and mixed back into the LPP address signal. This is because the mark recorded in the groove is mixed as a reproduction signal.

Next, another example of balance adjustment using a wobble detection differential balance circuit will be described with reference to FIG. FIG. 6 is a diagram showing the wobble detection balance adjustment path 60. The wobble detection balance adjustment path 60 is a wobble detection balance adjustment circuit 3 that adjusts a signal balance.
01, a differential amplifier circuit 302 that generates a wobble signal based on an output signal of the balance adjustment circuit 301, a band-pass filter 303 that extracts a wobble signal component based on the output signal of the differential amplifier circuit 302, A wobble signal binarization circuit 304 for binarizing a wobble signal which is an output signal of the bandpass filter 303, and a wobble for generating a clock necessary for recording / reproducing a disc based on the wobble binarization signal PLL circuit 305
A clock generator 306 for generating a clock for detecting the cycle or frequency of the wobble binary signal, and a counter for detecting the cycle or frequency of the wobble signal binary output using the clock generated by the clock generator 306 3
07, and a CPU 308 that reads the count value of the counter 307 and measures the wobble cycle or frequency.

Hereinafter, the principle of detection / measurement of the jitter amount of the wobble signal and the adjustment method using the above-described configuration will be described. During the recording operation or the reproducing operation of the optical disk recording / reproducing device 10 (FIG. 1), the CPU 308 sets the set value of the wobble detection balance adjustment circuit 301 to a given value. This value may be at the center of the electrical balance, or may be a settable minimum value. At this time, the cycle of the wobble binarized signal detected by the counter 307 (the cycle of the signal on the signal line indicated by a dashed line in the figure) is measured an arbitrary number of times, and the variation is calculated. Its value is CPU
Is temporarily stored in a storage unit (not shown). CPU
308 sets the next value in the wobble detection balance adjustment circuit, and similarly stores the variation amount of the wobble binary signal in another area of the storage unit. This operation is performed for all settings of the wobble detection balance adjustment circuit 301,
The value that minimizes the variation amount of the wobble binary signal is set as the optimal set value.

As a result of adjusting the signal balance in this manner, the mixing of the recording signal or the recorded information signal is minimized. Therefore, the level of the wobble binarization is BPF
For the output signal 303, the ideal value of the signal amplitude (50
%), The average light amount detection values of the two input signals to the wobble detection differential amplifier circuit 302 are adjusted to be equal. Here, the jitter amount of the binary signal of the wobble was observed. Instead, wobble P
The LL circuit 305 may be used to measure the amount of jitter of the frequency-divided signal of the output clock (jitter in the period of the signal indicated by the two-dot chain line in the figure). The frequency-divided signal is synchronized with the binary signal of the wobble, and is input to the PLL phase comparator.
Also, compared to the jitter of the binary signal of the wobble, P
When the LL circuit can generate a sufficiently stable clock, the jitter between the binary signal of the wobble input to the phase comparator of the wobble PLL circuit 305 and the frequency-divided signal of the output clock of the PLL circuit (in the figure) The jitter amount of the wobble signal can also be observed by observing the jitter between the signal of the signal line indicated by the one-dot chain line and the signal of the signal line indicated by the two-dot chain line.

For the calculation of the amount of variation, a method using the average value of the period and the standard deviation can be considered. Furthermore, it has been described that the search for the optimum set value is performed for all the settings. However, in practice, the optimum set value can be searched in a minimum time by using a binary search method or the like, The setting value can be more efficiently searched for using the adjustment value and the like.

A new clock generator was used as a clock for measurement. However, the wobble PLL circuit 305
Is stable compared with the wobble binary signal, the clock of the PLL circuit can be used in place of the clock generated by the clock generator.

Next, another example of balance adjustment using a wobble detection differential balance circuit and an LPP detection balance adjustment circuit will be described with reference to FIG. FIG. 7 is a diagram showing a wobble and LPP detection balance adjustment path 70. The wobble detection balance adjustment path (upper stage) of the wobble and LPP detection balance adjustment path 70 includes a wobble detection balance adjustment circuit 401 for performing balance adjustment of a signal input to the wobble detection differential amplifier circuit, and a balance adjustment circuit 401. , A wobble detection differential amplifying circuit 402 for generating a wobble signal from the output signal, a bandpass filter 403 for extracting a wobble signal component from the output signal of the differential amplifying circuit, and a bandpass filter 40
A wobble signal binarization circuit 404 for binarizing a wobble signal which is an output signal of No. 3 and a wobble PLL circuit 405 for generating a clock necessary for recording / reproducing the same disc from the wobble binarization signal A clock generator 406 for generating a clock for detecting the cycle or frequency of the wobble binary signal, and a clock generator 406
A counter 407 for detecting a time interval of a wobble signal binarized output from a pulse signal detected by the LPP detection circuit 414 using a clock generated by
And a CPU 408 for reading the count value of 7 and measuring the wobble cycle or frequency.

Further, in the wobble and LPP detection balance adjustment path 70, the LPP detection balance adjustment path (lower stage) is an LPP address detection balance adjustment circuit 409 for performing balance adjustment of a signal input to the LPP address detection differential amplifier circuit. An LPP detection differential amplifier circuit 410 for generating an LPP address signal from an output signal of the balance adjustment circuit, and a low-pass component extraction low-pass for detecting a land prepit address from the output signal of the differential amplifier circuit 410 A filter 411, an amplitude detection circuit 412 for detecting the amplitude of the wobble signal extracted by the band-pass filter 403, a bias generation circuit 413 for generating a bias voltage, and a voltage generated by the bias generation circuit 413 and an amplitude of the wobble signal. Using the voltage to which the signal is added as the comparison level, A land prepit detection circuit 414 for detecting a land prepit address signal, and a land prepit address detection circuit 415 for detecting a land prepit address from the land prepit binarized signal detected by the land prepit detection circuit 414. Including.

Hereinafter, another example of the balance adjustment by the above-described configuration will be described. The wobble detection balance adjustment and detection are performed as described above. The binarized wobble signal and LPP address signal are input to the counter by the above configuration. The counter 407 measures the time interval between the binary signal of the LPP address and the binary signal of the wobble using a clock generated by the clock generator 406. C
PU 408 can read the value. CPU4
08 measures this time interval an arbitrary number of times for each setting of the wobble detection balance adjustment circuit. Then, the variation amount is calculated in the same manner as described in the above example. Where L
Since the binarized signal of the PP address is a pulse-like detection signal as shown in FIG. 5, it is detected stably even with a slight LPP detection balance setting deviation. Therefore, LP
There is no problem in using the binary signal of the P address as a reference signal for detecting the jitter of the wobble signal.

Further, in this example, the method of adjusting the wobble detection balance by measuring the jitter amount of the binary signal of the wobble based on the binary signal of the LPP address has been described. However, as an alternative signal to the binarized signal of the LPP address, the LPP address detection circuit 415 may further detect the address, decode the address, and use the address detection confirmation signal at that time. However, in this case (especially at the time of recording by the optical disk recording / reproducing apparatus 10 (FIG. 1)), it is desirable that the LPP detection balance adjustment has been completed.

If the balance adjustment of the wobble balance adjustment circuit 401 is not properly performed, the jitter amount of the binary signal of the wobble is large, and the wobble PL in the subsequent stage is large.
In some cases, the L circuit 405 cannot normally generate a clock synchronized with the wobble binary signal, and thus cannot detect the LPP address. However, using this,
The address detection rate in the LPP address detection circuit 415 is represented by C
The wobble detection balance adjustment circuit can be adjusted while observing with the PU 408.

As described above, by adjusting the wobble detection differential balance adjustment circuit and the LPP detection differential balance adjustment circuit, an optical disk device that stably detects the LPP address in both data recording / reproduction is realized. it can.

The tracking detector 203a
If (FIG. 2) is divided into more than two (e.g. four, six) detectors, the output of the detector on one side of the dividing line along the track and the other side Is used. For example, the differential signal can be obtained as the difference between the average value of the output of the detector on one side of the dividing line and the average value of the output of the detector on the other side.

[0072]

The guide groove of the disk is modulated in the radial direction (the direction along the track) at a frequency serving as a clock reference signal required for reproducing / recording information. According to the present invention, the differential operation circuit for detecting the modulation signal and the differential operation circuit for detecting the LPP address are separately provided, so that the wobble signal and the LP signal are ideally provided.
The P address signal can be detected. Therefore, an optical disk (DVD-R / RW) on which address information for recording is not formed on a track on which information is recorded is formed.
Etc.), the detection rate of the address information can be significantly increased regardless of the recording / reproducing state of the apparatus.

Further, by adding an AGC circuit for controlling the gain and making the signal amplitude of the high frequency component of the light amount signal detected by the tracking detector constant, disturbance such as defocusing, off-track and tilt of the optical head can be achieved. The read margin of the LPP address can be expanded with respect to the factor.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disc recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a groove shape of a disk.

FIG. 3 is a diagram illustrating an operation of the optical disc recording / reproducing apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating two output signals of an LPP detection balance adjustment circuit.

FIG. 5 is a diagram for explaining the operation of the optical disc recording / reproducing apparatus according to the embodiment of the present invention.

FIG. 6 is a partial block diagram of the optical disc recording / reproducing apparatus according to the embodiment of the present invention.

FIG. 7 is a partial block diagram of the optical disc recording / reproducing apparatus according to the embodiment of the present invention.

FIG. 8 is a block diagram of a conventional device.

FIG. 9 is a diagram illustrating the operation of a conventional device.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kenji Koishi 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Yutaka Nagata 3-12, Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside of Victor Company of Japan (72) Inventor Mitsuru Ota 3--12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Victor Company of Japan In-house (72) Inventor Taku Kawai 3-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term in JVC, Ltd. (Reference) 5D090 AA01 BB04 CC04 CC05 DD03 DD05 EE17 EE18 FF07 GG03 GG10 GG28 GG36 5D118 AA14 CD03 CD07

Claims (8)

[Claims] 1. An optical disk device for reading out address information from an optical disk having a track on which information is recorded and an inter-track portion formed between the tracks and recording address information for specifying a position, comprising: An optical head for irradiating the optical disk with a laser,
An optical head that is divided into a first detector and a second detector in the track direction, and each includes a tracking detector that detects a reflected light from the optical disc and outputs a detection signal; The first detection signal output from the first detector and the second detection signal output from the second detector are received, and at the position where the address information is recorded, the first detection signal and the second detection signal are received. , And an address detection balance adjustment circuit for adjusting the amplitude of the detection signals and outputting the respective signals, and the difference between the first detection signal and the second detection signal adjusted by the address detection balance adjustment circuit. An address detection differential operation circuit for outputting a certain address detection differential signal; and the address detection differential signal output from the address detection differential operation circuit. Based on, with an address detection circuit for detecting the address information, the optical disk apparatus. 2. The apparatus according to claim 1, further comprising an amplitude detection circuit for detecting an amplitude of the first detection signal and the second detection signal, wherein the address detection balance adjustment circuit detects the first detection signal detected by the amplitude detection circuit. Based on the amplitude of the signal and the amplitude of the second detection signal, the amplitude of the first detection signal and the amplitude of the second detection signal are adjusted to be substantially equal, and each is output. An optical disk device according to claim 1. 3. The apparatus according to claim 2, further comprising: a detection unit configured to detect a read rate of the address information, wherein the address detection balance adjustment circuit controls the first detection signal and the first detection signal so as to maximize the read rate detected by the detection unit. The optical disk device according to claim 1, wherein the amplitude of the second detection signal is adjusted. 4. The optical disk has wobbles formed at a predetermined period in a radial direction for controlling rotation, and the optical disk device includes a first detection signal and a second detection signal. And adjusting the signal level of the first detection signal and the signal level of the second detection signal to be substantially equal,
A wobble detection balance adjustment circuit that outputs each of them; a wobble that outputs a wobble detection differential signal that is a difference between the first detection signal and the second detection signal adjusted by the wobble detection balance adjustment circuit. 3. The optical disk device according to claim 2, further comprising: a detection differential operation circuit; and a wobble signal detection circuit that detects the wobble based on the wobble detection differential signal output from the wobble detection differential operation circuit. . 5. A wobble detection balance adjustment circuit, comprising: a signal level of the first detection signal based on a wobble jitter amount detected by the wobble signal detection circuit;
The optical disk device according to claim 4, wherein the signal level of the second detection signal is adjusted to minimize the jitter amount. 6. A wobble detection balance adjustment circuit, further comprising a detection unit for detecting a read rate of the address information, wherein the wobble detection balance adjustment circuit maximizes the read rate detected by the detection unit. The optical disk device according to claim 4, wherein the signal level of the second detection signal and the signal level of the second detection signal are adjusted. 7. The optical disc device according to claim 4, further comprising a gain control circuit for keeping the amplitudes of said first detection signal and said second detection signal constant. 8. A method for reading out address information from an optical disc having a track on which information is recorded and an inter-track portion formed between the tracks and having address information specifying a position recorded thereon, Irradiating the optical disk with a laser; detecting a reflected light from the optical disk by each of a first detector and a second detector divided in the track direction; and outputting a detection signal; A first detection signal output by the first detector and a second detection signal output by the second detector are received, and at the position where the address information is recorded, the first detection signal and the second detection signal are output. Adjusting the amplitudes of the two detection signals and outputting each of the two detection signals; and the first detection signal whose respective amplitudes are adjusted, and
An information reading method, comprising: outputting an address detection differential signal that is a difference between the second detection signals; and detecting the address information based on the output address detection differential signal.