JP2002260237A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device which can precisely position a light beam spot at the center of an information recording track even if a land prepit is formed partially on the inner circumference side or outer circumference side of a land. SOLUTION: Based on the sum signal of each received signal from the division light receiving part of a photodetector 4 which receives a reflected light from an optical disk 1 in which a land part with the land pit formed in it and a groove ditch with information recording mark recorded in its center are alternately formed in the direction of the radius of the disk, a correction means 7 which outputs an offset correcting voltage so that the amplitude of an RF signal obtained from the information recording mark may be maximum is provided, and the light beam spot S can precisely be positioned at the center of the information recording track even when the land prepit is formed partially on the inner circumference side or outer circumference side of the optical disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device, and more particularly, to an optical disk device in which pre-pits including address information are formed on guide tracks.

[0002]

2. Description of the Related Art A swell (hereinafter, referred to as an undulation) formed on an optical disc.
An optical disk in which auxiliary information (hereinafter, referred to as land pre-pits) such as a synchronization signal and address information is recorded in advance in a land portion existing between the groove grooves, which can be recorded and reproduced in a groove groove having a wobble, is a DVD-ROM. RW
(Proposed by the DVD Forum). In a recording / reproducing apparatus for a recordable / reproducible optical disk having such a format, not a groove but a synchronization signal and address information for a position search recorded in advance in a land prepit in a different system from the reproduction signal. When reading, to make the light beam spot follow the information recording track formed on the optical disk, a method of obtaining a tracking error signal from the difference signal of the diffracted light distribution from the guide track, so-called push-pull tracking method is adopted. Have been.

However, in this push-pull tracking method, when the objective lens is moved so that the light beam spot follows the eccentric component of the disk for tracking control, the diffraction distribution on the photodetector also moves. Due to the movement of the diffraction distribution, an offset occurs in the tracking error signal. Also, when the disc is tilted, the balance between the two photodetectors arranged in parallel with the track is lost, and the tracking error signal does not become zero even when the light beam spot is at the center of the information recording track, that is, the track An offset will occur. Therefore, there is a problem that the light beam spot cannot be accurately positioned at the center of the information recording track.

As a countermeasure against such a problem, Japanese Unexamined Patent Publication No. 11-96570 discloses an improved tracking error signal generating means, which detects information on a light beam spot based on land prepit signals on both sides of an information recording track. A method is disclosed in which the amount of displacement from the center of the recording track is detected to control the positioning of the light beam spot at the center of the information recording track.

[0005]

However, in a recordable optical disk and a recording / reproducing apparatus having such a format, since recording is performed at a constant linear velocity, there are portions where adjacent wobbles have an opposite phase. For example, FIG.
FIG. 4 is a diagram conceptually showing a portion of a conventional optical disc where adjacent wobble phases have opposite phases. Here, the grooves G21, G22 and G23 are information recording tracks. In FIG. 8, among the three grooves G21, G22, G23 adjacent in the disk radial direction, the phase of the wobble formed in the groove G22 between the grooves G22 and the adjacent groove 21 is inverted as indicated by I, Similarly, the phases of the wobbles of the grooves G22 and G23 are also inverted.

The reason that the adjacent wobbles take an opposite phase is that the wobbles have a constant linear velocity (CLV: Constant).
This is because it has been recorded to be Linear Velocity. In such a case, the crosstalk from the signal recorded in the adjacent groove becomes large in a portion where the distance from the adjacent groove becomes short, causing a data error due to signal deterioration, or an adjacent data already recorded at the time of recording. Erroneous erasure of tracks occurs. In such a part,
The output of the land pre-pit signal may not be sufficiently obtained, or reading may be affected. Therefore, it is necessary to take measures such as not recording the land pre-pits in the portion where the wobble phases are opposite to each other between the adjacent grooves.

In the above-mentioned optical disk recording / reproducing apparatus, land pre-pits on both sides of the information recording track are always used in order to detect the displacement of the light beam spot on the information recording track. Next, it is not known which land prepit is detected on the outer peripheral side or the inner peripheral side. In addition, since the timing for detecting the land pre-pit is not synchronized with the wobble, it is difficult to make the timing for detection.

For this reason, it has been considered that wobbles have the same phase between adjacent grooves, land prepits are formed on lands between the grooves, and recording is performed at a constant angular velocity in the same zone. This will be described in detail with reference to FIG. FIG. 9 is a diagram showing a tracking shift detection signal in the case where wobbles have the same phase between adjacent grooves, and a land prepit is formed at the center of the land between the grooves. FIG. 4B is a diagram showing a land pre-pit formed at the center of the groove G, and FIG. 4B is a diagram showing a wobble signal and a pre-pit signal when the light beam spot traces along the center of the groove G2; FIG. 3D is a diagram showing a wobble signal and a land pre-pit signal when the light beam spot traces the groove G2 with a bias toward the outer periphery of the disk, and FIG. It is a figure showing a difference value of a land pre-pit signal at the time of tracing groove G2.

In FIG. 9A, a dotted line M indicates a trajectory of the light beam spot traced along the center of the groove G2, and a solid line N indicates a light beam spot located in the groove G2 and located on the outer peripheral side. Biased, showing the trajectory to trace,
In (B) and (C), the polarity of the land pre-pit signal is-when the land pre-pit is detected on the outer circumference side of the disk from the groove G2, and + when the land pre-pit is detected on the inner circumference side of the disk. As shown in FIG.
The difference value of the land pre-pit signal when the light beam spot traces along the center of the groove G2,
Represents the difference value of the land pre-pit signal when the light beam spot is located in the groove G2 and traced toward the outer peripheral side.

In the radial direction of the disk, a groove G
1, G2, G3 and lands L1, L2 are formed alternately adjacent to each other, and the three grooves G1, G2, G3 have the same phase. At the center of the land L1 between the grooves G1 and G2 corresponding to the peak position of the wobble amplitude, three land prepits p11, p12 and p13 are arranged in the disk circumferential direction.
Are formed as a set, and a set of land prepits p22 and p23 in the circumferential direction of the disk is provided at the center of the land L2 between the grooves G2 and G3 corresponding to the peak position of the wobble amplitude. Are formed, and these land prepits p11, p1
2, p13, p22, and p23 have the same distance from the groove G2. These pre-pit groups are formed so as to shift the phase in the circumferential direction of the disk for each track. Normally, three land pits constitute a set of land pre-pits, but one of the land pre-pits formed on the land L2 is omitted.

Therefore, when the push-pull method is used, when the light beam spot traces the groove G2, the land prepits p11 and p1 formed on the land L1
Since the difference value between the land prepit signals of the land prepits p22 and p23 formed on the land L2 is negative, the offset correction is performed so that the light beam spot is located at the center of the groove G. Position can be controlled.

More specifically, the position of the light beam spot S can be controlled and traced at the center of the groove G2 by offset correction as described below. FIG.
As shown by the dotted line M in (A), when the light beam spot traces along the center of the groove G2,
As shown in (B), the difference between the magnitude of the land prepit signal between the land prepits p11, p12, p13 formed on the land L1 and the land prepits p22, p23 formed on the land L2. However, the difference value of the land pre-pit signal is 0. In this case, FIG.
As shown in (D), it is not necessary to correct the track shift detection signal.

As shown by the solid line N in FIG.
The light beam spot is deviated to the outer periphery of the disc and the groove G
2 is traced, the land pre-pits p22 and p2 formed on the land L2 as shown in FIG.
Since the land pre-pit signal of No. 3 is larger than the pre-pit signals of the land pre-pits p11, p12 and p13 formed on the land L1, the difference value of the land pre-pit signal is-. In this case, as shown in FIG. 9D, by correcting the difference value of the land pre-pit signal to 0, the position can be controlled so that the light beam spot is traced to the center of the groove G2. In addition,
The light beam spot is deviated toward the inner circumference of the disc,
In the case of tracing No. 2, the position of the light beam spot can be controlled so as to trace the center of the groove G2 in the same manner as when the light beam spot is deviated toward the outer periphery of the disk and traces the groove G2.

However, the land prepits p11, p12 and p13 formed on the land L1 and the land prepits p22 and p23 formed on the land L2 are closer to the inner circumference or outer circumference of the disk than the center of the lands L1 and L2. In the case where the recording was performed on the side, the light beam spot could not be traced along the center of the groove G2.

This will be described with reference to FIG. First, a case in which the entire land prepit is recorded on the outer periphery side will be described. FIG. 10 is a diagram showing a tracking shift detection signal when the wobbles have the same phase between adjacent grooves, and the land prepits formed on the lands between the grooves are more deviated toward the outer periphery of the disc than the center of the lands. (A) is a diagram showing a state in which land prepits are formed more deviated toward the outer periphery of the disc than the center of the land, and (B) is a light beam spot traced along the center of the groove G2. FIG. 4 is a diagram showing a wobble signal and a land pre-pit signal in the case;
(C) is a diagram showing a wobble signal and a land pre-pit signal when the light beam spot is deviated to the outer periphery of the disk and traces the groove G2, and (D) is a diagram in which the light beam spot is at the center or the outer periphery of the disk. FIG. 14 is a diagram showing a difference value of a land pre-pit signal when the groove G2 is traced in a biased manner.

FIG. 10A corresponds to each of FIG. 9A and shows land prepits p11 and p1.
The only difference is that all of p2, p13, p22, and p23 are formed so as to be entirely biased toward the outer periphery of the disk. FIG.
As shown by the dotted line M in FIG. 10A, when the light beam spot S traces along the center of the groove G2, as shown in FIG.
23 is formed so as to be more deviated to the outer peripheral side than the center of the land L2, the land prepit signals of the land prepits p22 and p23 formed on the land L2 are −
The land prepit signals of the land prepits p11, p12, and p13 formed on the land L1 are +
And the magnitude of the land prepit signals of the land prepits p22 and p23 is equal to that of the land prepits p11 and p1.
2, smaller than the land pre-pit signal of p13.

Therefore, as indicated by R in FIG. 10D, the difference value of the land pre-pit signal is +. This causes a track shift even though the light beam spot S traces along the center of the groove G2. Therefore, the light beam spot S is corrected so as not to cause the track deviation, and the light beam spot S traces from the center of the groove G2 toward the inner peripheral side of the disk. For this reason, it is impossible to trace the light beam spot by controlling the position of the light beam spot at the center of the groove G2.

As shown by the solid line N in FIG. 10A, when the light beam spot S traces the groove G2 toward the outer periphery of the disk, as shown in FIG. The land pre-pit signals of the land pre-pits p22 and p23 formed at-are-,
A land pre-pit p11 formed on the land L1,
The land prepit signals of p12 and p13 are +,
The magnitudes of the land prepit signals of the land prepits p22 and p23 are the same as those of the land prepits p11, p12 and p1.
3 is substantially equal to the land pre-pit signal. Therefore, FIG.
As indicated by Q of 0 (D), tracking deviation detection is not performed even though the light beam spot S traces the groove G2 from the center of the groove G2 toward the disk outer periphery.

For this reason, the light beam spot S is traced while being deviated toward the outer peripheral side at the center of the groove G. As a result, the light beam spot S cannot be traced by controlling the position of the center of the groove G2. Similarly, even when the entire land prepit is recorded on the inner peripheral side of the disk, the position cannot be controlled so that the light beam spot is traced to the center of the groove G2. Here, the information recording tracks are the grooves G1, G2, and G3.

The present invention has been made in order to solve the above-described problems, and it is possible to record an optical beam spot even if land prepits are formed on the inner or outer side of the land. It is an object of the present invention to provide an optical disk device capable of accurately controlling the position at the center of a track (groove groove).

[0021]

According to a first aspect of the present invention, there is provided an optical disc apparatus which is formed concentrically or spirally from an innermost circumference to an outermost circumference and has an information recording mark recorded at a central portion. A groove groove and land portions continuously formed between the groove grooves are provided. In this land portion, auxiliary information used for recording or reproducing an information signal in the groove groove is recorded in advance as land prepits. The groove groove and the land portion are divided in advance into a plurality of zones in the disk radial direction, and the groove groove has a constant frequency on both sides of the groove groove in the disk circumferential direction. The wobbles are continuously wobbled, and the phase of each wobble of the groove adjacent in the disk radial direction in each of the plurality of zones is the same, A pre-pit group consisting of a plurality of land pre-pits arranged for each wobble cycle in a land portion is recorded in a radial direction of the disk, and between adjacent land portions, a phase in a circumferential direction of the disk is recorded at a different position. An optical disc apparatus for recording or reproducing an information signal by irradiating a light beam spot from a light source to an optical disc, wherein reflected light of the light beam spot applied to the groove is tangential to a groove of the optical disc. At least 2 parts by a dividing line optically parallel to the
Based on a photodetector received by the divided light receiving unit and a difference signal of a light receiving signal output from each of the divided light receiving units of the photodetector, a displacement between the light beam spot and the groove is pushed. A first method for detecting a pull method and generating a first track shift detection signal for causing the light beam spot to follow the groove groove;
Track deviation detecting means, and a wobble signal detecting means for extracting a frequency component of the wobble and detecting a wobble signal, based on a difference signal between the light receiving signals respectively output from the divided light receiving units of the photodetector, A wobble signal output from the wobble signal detection means and a light reception signal output from each of the divided light receiving units of the photodetector are input, and an inner land pre-pit signal and an outer land are input based on the wobble signal. Generating a second track shift detection signal indicating a shift of the light beam spot from a center of the groove from a difference value from a pre-pit signal;
Track deviation detecting means, based on the sum signal of the light receiving signals respectively output from the divided light receiving units of the photodetector,
TE offset calibration means for generating an offset correction voltage so that the amplitude of the RF signal detected from the information recording mark is maximized; and a signal obtained by adding the second track shift detection signal and the offset correction voltage to the signal. The position of the light beam spot on the optical disk is controlled to move in the width direction of the groove by the tracking error signal obtained by synthesizing the first track shift detection signal, and the center of the groove is controlled. Rotating the optical disk at the same rotational speed in at least the same zone of the plurality of zones based on a wobble signal from the wobble signal detecting unit and a reference clock. Optical disk rotating means for rotating the optical disk. According to a second aspect of the present invention, in the optical disk device according to the first aspect, the TE offset calibrating means is configured to generate an RF signal based on a sum signal of reception signals of the information recording marks detected by a divided light receiving unit of the photodetector. RF detection means for detecting the RF amplitude of the RF signal, sample-and-hold means for detecting and holding the RF amplitude of the RF signal, analog-to-digital conversion means for digitizing the sampled and held RF amplitude, It is characterized by comprising a digital signal processor that outputs an offset correction voltage so as to obtain a value, and digital-to-analog conversion means that converts the offset correction voltage into an analog signal.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk device according to an embodiment of the present invention will be described with reference to FIGS. The same components as those of the conventional example are denoted by the same reference numerals, and description thereof will be omitted. Figure 1
1 is a block diagram of an optical disk device according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing grooves and land prepits on an optical disk used in the optical disk device according to the embodiment of the present invention. FIG. 3 is a schematic diagram of a zone arrangement in an optical disk used in the optical disk device according to the embodiment of the present invention. FIG. 4 is a diagram showing a specific arrangement of grooves and land prepits on an optical disk used in the optical disk device according to the embodiment of the present invention. FIG.
FIG. 4 is a block diagram of a second track deviation detecting unit in the optical disk device of the present invention. FIG. 6 is a block diagram of the TE offset calibrating means in the optical disk device of the present invention. FIG. 7 is a timing chart for explaining the operation of the optical disk device of the present invention.

As shown in FIG. 1, the optical disk apparatus of the present invention comprises a spindle motor 2 for rotating an optical disk 1, a light source 3 such as a semiconductor laser for irradiating a light beam spot S on the optical disk 1, and a light source 3. A photodetector having a divided light receiving portion divided at least into two by a dividing line optically substantially parallel to a tangential direction of a groove groove of the optical disc 1 and receiving reflected light from a light beam spot S applied to the optical disc 1 4 and the output signal of the photodetector 4 to detect the positional deviation between the light beam spot S and the track (here, a groove) by a push-pull method, and to output a first track deviation detection signal TE1. The wobble signal W outputted from the track deviation detecting means 5 and the wobble signal detecting means 12 and the light receiving signal outputted from the divided light receiving section of the photodetector 4 respectively. And the deviation of the light beam spot S from the center of the groove G2 based on the wobble signal W and the difference between the inner land pre-pit signal A 'and the outer land pre-pit signal B'. On the basis of the sum signal of the second track shift detection unit 6 that generates the second track shift detection signal TE2 and the light receiving signals A and B output from the divided light receiving units of the photodetector 4, the groove G2
Track error offset calibrating means 7 (hereinafter, referred to as TE offset calibration) for generating an offset correction voltage so that the amplitude of a high-frequency signal (hereinafter, referred to as RF signal) detected from an information recording mark recorded at the center of the block is maximized. A first adding means 8 for adding the second track deviation detection signal and the offset correction voltage output from the TE offset calibrating means 7; and an output of the first adding means 8 and a first A second adding means 9 for adding the output of the track deviation detecting means 5, a moving means 10 for moving the position of the light beam spot S in a direction substantially perpendicular to the track direction of the optical disc 1 (track width direction), and a second A track control means 11 for controlling the moving means 10 so that the light beam spot S follows the track by a signal output from the adding means 9; A wobble signal detecting means for extracting a frequency component of the wobble based on a difference signal of the light receiving signal output from each of the divided light receiving sections, and generating a reference clock serving as a reference of the wobble signal. A reference clock generator 13 for controlling the spindle motor 2 so that the frequency of the wobble signal is always constant based on the reference clock.
And motor control means 14 for controlling the rotation of the motor.

Here, an optical head 15 is formed by integrating a light source 3, a photodetector 4, and an optical system for condensing light emitted from the light source 3 on the optical disk 1 or guiding the light to the photodetector 4. The optical head 15 is driven by the moving means 10 and moves in the radial direction of the optical disc 1. Further, the first track deviation detecting means 5 has a conventionally known configuration, and as described above, detects the positional deviation between the light beam spot S and the track from the output signal of the photodetector 4 by a known push-pull method. A first track shift detection signal obtained by the detection is output. FIG. 1 does not show a recording system and a reproduction system. The recording system modulates a laser beam emitted from the light source 3 with an information signal for recording, and the reproduction system obtains a reproduction signal based on a signal detected by the same or different photodetector as the photodetector 4. Configuration. The grooves G1, G2 and G3 are information recording tracks, as in the conventional example.

Next, before describing the detailed configuration and operation of the optical disc apparatus according to the embodiment of the present invention, first, the format of the optical disc 1 to be recorded or reproduced by the optical disc apparatus according to the embodiment of the present invention will be described with reference to FIGS. 4 will be described. The optical disc 1 includes groove grooves (hereinafter, also simply referred to as “grooves”) formed concentrically or spirally from the innermost side toward the outermost side.
Land portions (hereinafter, also simply referred to as lands) are respectively formed continuously between the groove grooves. Auxiliary information used for recording information signals in the groove grooves is pre-recorded in the land portions as land pre-pits. It is an optical disk that has been used. Specifically, as shown in FIG. 2, such an optical disk 1 is adjacent to a groove G2 between three bluebs G1, G2, G3 adjacent in the optical disk radial direction in the embodiment of the present invention. Grooves G1 and G
The wobble phase formed in each of the zones 3 is always equal for each zone described later.

In the land L1 between the grooves G1 and G2, three land prepits p11, p12 and p13 of a wobble cycle are recorded in advance corresponding to the peak position of the wobble amplitude. These three land prepits p11, p12 and p13 form one prepit group, and these three land prepits p1
The 1-bit data value is expressed as “1” or “0” by a combination of whether 1, 1, p12 and p13 exist or not.
An information recording mark (not shown) is recorded at the center of the grooves G1, G2, G3.

The optical disk 1 is recorded at a constant angular velocity (CAV) in the same zone, and the phases of adjacent wobbles are always equal over the area where digital information is recorded. Are in opposite phases, and the reproduction data does not deteriorate due to the increase in crosstalk from the adjacent track. Also, no problem arises with the land prepit signal due to the wobbles being out of phase.

As shown in FIG. 3, the recording area of the optical disk 1 is concentric with zone 0 to zone N-.
It is divided into a total of N zones up to one, and the phases of wobbles and land prepits in each zone are formed as shown in FIG. For example, in the case of an optical disk having a radius of 12 cm, each zone is composed of 1024 tracks, and the number N of zones is 83. As shown in FIG. 4, the optical disc 1 used in the embodiment of the present invention forms one pre-pit group with three land pre-pits p11, p12 and p13, and includes one pre-pit group from the pre-pit group to the next pre-pit group. The length is set to be equal to the length of a sync block which is one of the divisions of the recording data.

In the optical disc 1, prepit groups are formed in advance so as to be arranged for each sync block in the disc circumferential direction and to shift the phase in the disc circumferential direction for each track. The land prepits are not arranged on the adjacent lands, and there is no interference from the land prepits of the adjacent lands. Further, a land pre-pit signal can be generated from a reproduced signal without requiring a complicated processing circuit.

In order to make such an arrangement, the number of pre-pit groups per track is set to an odd number, or a reference phase during one rotation of the optical disk is determined, and the phase of the pre-pit group is switched for each track. What should I do? The positional relationship between the land prepits is kept in phase with the wobble, so detection is easy. By detecting at a specific phase of the wobble, erroneous detection due to dust, scratches or defects on the optical disk Can be prevented.

Next, each configuration of the optical disk device will be described. The second track deviation detecting means 6 in the optical disk device shown in FIG. 1 has a configuration shown in FIG. As shown in FIG. 5, the second track deviation detecting means 6 receives as input the received signals A and B detected by the photodetector 4 of FIG. 1, and extracts the inner peripheral land pre-pit signal A '. A first auxiliary information detecting unit 61, a second auxiliary information detecting unit 62 for extracting the outer peripheral side land pre-pit signal B ', a first high-pass filter 63 (hereinafter, referred to as a first HPF 63), A second high-pass filter 64 (hereinafter, referred to as a second HPF 64), a first holding unit 65, a second holding unit 66, and a wobble signal are received as inputs.
A gate means 67 for supplying a gate signal to one of the first and second holding means 65 and 66;
Subtracting means 68 for subtracting the output signals C and D output from 66 to output an output signal E; low-pass means for filtering low-frequency components of the output signal E and outputting a track deviation detection signal TE 69.

As shown in FIG. 6, the TE offset calibrating means 7 receives the information recording mark received signal A, which is recorded at the center of the groove G2 detected by the divided light receiving section of the photodetector 4 in FIG. RF detecting means 71 for generating an RF signal from an information recording mark recorded at the center of the groove 2 based on the sum signal of B,
A sample and hold unit 72 for detecting and sampling and holding the RF amplitude, an ADC (analog-to-digital conversion unit) 73 for digitizing the sampled and held RF amplitude, and an offset correction voltage for maximizing the RF amplitude. DSP (digital signal
(A processor) 74 and a DAC (digital / analog conversion means) 75 for converting the digital offset correction voltage into an analog signal.

Next, a tracking method using the optical disk device will be described. Here, a case where the light beam spot S traces the center of the groove G2 will be described. At the time of recording or reproduction, the optical disc 1 shown in FIG.
By inputting the wobble signal output from the wobble signal detection means 12 and the wobble signal to the motor control means 14, the spindle motor 2 is rotationally controlled based on the reference clock so that the wobble frequency is always constant.
In the same zone, it rotates at a constant angular velocity.

The rotating optical disk 1 is irradiated with a light beam spot S from a light source 3, and reflected light from the light beam spot S condensed on the optical disk 1 is incident on a photodetector 4. Thereafter, the photodetector 4 photoelectrically converts the received light signal at a level corresponding to the amount of incident reflected light into first track shift detecting means 5, second track shift detecting means 6, TE offset calibrating means 7, It is supplied to the wobble signal detecting means 12 respectively.

Here, the first track deviation detecting means 5
Is configured to detect the displacement between the light beam spot S and the groove G2 by a known push-pull method.
A photodetector 4 having at least two divided light receiving sections divided by a division line optically substantially parallel to the tangent direction of each of the grooves G1, G2, G3 of the optical disc 1 is used. On the basis of the signal level difference, the light beam spot S is formed so that the light amount of the light receiving area of the light incident on the two-divided light receiving unit becomes equal.
2 is a first track deviation detection signal TE1 for following operation on
Is generated and supplied to the second adding means 9.

On the other hand, the wobble signal detecting means 12 generates a differential signal of the two-part light receiving unit based on the light receiving signals A and B input from the two-part light receiving unit of the photodetector 4, and performs recording and reproduction. A wobble frequency component, which is a frequency component lower than the signal frequency band, is frequency-selected and extracted, and supplied to the second track deviation detecting means 6 and the motor control means 14, respectively.

The second track deviation detecting means 6 shown in FIG.
Then, the following processing is performed. The inner peripheral land pre-pit signal A 'is extracted by the first auxiliary information detecting unit 61 and the first HPF 63 based on the light receiving signals A and B detected by the two-part light receiving unit of the photodetector 4 in FIG. Then, the signal is supplied to the first holding means 65 and the gate means 67, respectively, and the outer peripheral side land pre-pit signal B 'is supplied by the second auxiliary information detecting means 62 and the second HPF 64 based on the light receiving signals A and B. It is extracted and supplied to the second holding means 66 and the gate means 67, respectively.

The first auxiliary information detecting means 61 obtains a difference signal obtained by subtracting the received light signal B from the received light signal A by the differential circuit 101 from the received light signals A and B, and then performs half-wave rectification by the diode 103. And the inner land pre-pit signal A '
, And unnecessary low frequency components are removed by the first high-pass filter 63. Similarly, in the second auxiliary information detecting section 62, the received light signals A and B are
2, a difference signal obtained by subtracting the light receiving signal A from the light receiving signal B is obtained, half-wave rectified by the diode 104 to extract the outer peripheral side land pre-pit signal B ', and unnecessary low frequency components are extracted by the second HPF 64. Remove.

The gate means 67 generates a gate signal using the wobble signal W in the wobble signal detection means 12, and passes the gate signal through the land prepit on the inner peripheral side in the phase where the land prepit of the wobble exists. Is output to the first holding means 65 during the operation, and is output to the second holding means 6 when passing through the land pre-pits on the outer peripheral side.
6 and output. At this time, the gate signal is generated so as to be sampled with a width including a land prepit existing during a high level period of the wobble signal with reference to a predetermined timing position of the wobble signal W.

The first holding means 65 outputs an inner-land land pre-pit maximum value holding signal C of the inner-land land pre-pit signal A 'in each pre-pit group, and the second holding means 66 After that, the outermost land prepit signal B ′ of the outermost land prepit signal B ′ is output in each land prepit. In this way, even if land pre-pits are missing or cannot be detected properly, one of the pre-pit groups can always be detected accurately. Further, no false signal is output even if the land prepits are not alternately arranged on the inner side and the outer side.

A subtraction means 68 subtracts the maximum value signal C for holding the maximum value of the inner-side land pre-pits output from the first holding means 65 and the maximum value signal D for holding the outer-side land pre-pits output from the second holding means 66. To obtain a difference value E. Then, the difference value E is removed by the low-pass means 69 to remove the high-frequency component to obtain a second track shift detection signal TE2. Then, the second track deviation detection signal TE2 is supplied to the first adding means 8.

As shown in FIGS. 6 and 7, the TE offset calibrating means 7 uses the RF signal based on the sum signal of the light receiving signals A and B inputted from the two-part light receiving portion of the photodetector 4.
The detecting means 71 generates an RF signal detected from the information recording mark recorded at the center of the groove G2,
The sample and hold means 72 converts this RF signal into R
The F amplitude is detected, supplied to the ADC 73, digitized, and supplied to the DSP 74. The DSP 74 outputs an offset correction voltage corresponding to the RF amplitude to the first adding means 8 via the DAC 75 while monitoring the RF amplitude. Then, this offset correction voltage is additionally supplied to the first adding means 8, the optical head 15 is moved via the moving means 10 and the tracking control means 11, and the position control of the light beam spot S is performed, so that the groove G2 is controlled. The central part can be traced.

Here, the land pre-pits p11, p1
A method for tracing the light beam spot S at the center of the groove G2 when 2, p13, p22, and p23 are formed so as to be deviated toward the inner circumference or the outer circumference of the disk will be described. (Land pre-pits p11, p12, p13, p22,
As shown in FIG. 7, in step 1, based on the sum signal of the light receiving signals A and B input from the two-divided light receiving portion of the photodetector 4, as shown in FIG. Then, the RF amplitude when the offset correction voltage output from the TE offset calibration means 7 is 0 V is monitored. Next, in step 2, the offset correction voltage is increased from 0 V to the + side by a small voltage ΔV (for example, 10 mV) and supplied to the first adding means 8. The tracking error signal TE obtained by combining the first tracking error signal TE1 with the signal obtained by adding the minute voltage ΔV to the second tracking error signal TE2 is supplied to the tracking control means 11, and the moving means 10, the tracking control means The optical head 15 is moved via 11 to change the position of the light beam spot S. In this case, since the light beam spot S is shifted from the center of the groove G2, the RF amplitude of the RF signal detected from the information recording mark recorded at the center of the groove G2 is such that the light beam spot S is Since it is lower than when it is at the center of the groove G2, the process returns to step 2 in step 3, and further supplies an offset correction voltage to the first adding means 8 on the + side.

In step 4, when the offset correction voltage is supplied to the + side, the RF amplitude does not increase. When it is determined that the maximum value of the RF amplitude is on the + side of the offset correction voltage, the process proceeds to step 8. By supplying the offset correction voltage that maximizes the RF amplitude to the first adding means 8, the position of the light beam spot can be moved and the light beam spot S can be traced to the center of the groove G2.

(Land pre-pits p11, p12, p1
3, when the entirety of p22 and p23 are biased toward the inner circumference of the disk) Similarly to the above, in step 1, the sum of the light receiving signals A and B input from the two-part light receiving portion of the photodetector 4 Based on the signal, the RF amplitude when the offset correction voltage output from the TE offset calibration means 7 is 0 V is monitored. Next, in step 2, the offset correction voltage is shifted from 0 V to the + side by a minute voltage ΔV (for example, 10 m
V) and supplies it to the first adding means 8. This minute voltage ΔV is added to the first and second tracking error signals TE1 and TE2 to generate a tracking error signal TE, which is then supplied to the tracking control means 11, and the optical head 15 is moved via the moving means 10 so that the light beam The position of the spot S is changed. Also in this case, similarly to the above, since the light beam spot S is shifted from the center of the groove G2, the RF amplitude of the RF signal detected from the information recording mark recorded at the center of the groove G2 is Since the spot S is lower than when the spot is at the center of the groove G2, the process proceeds to step 5 via steps 3 and 4, and in this step 5, the minute voltage ΔV
(For example, 10 mV) is supplied to the first adding means 8 in the same manner as described above. In step 6, this small voltage ΔV
Is added to the second tracking error signal TE2 and the tracking error signal TE obtained by synthesizing the first tracking error signal TE1 to the tracking control means 11, and is supplied to the tracking control means 11 via the moving means 10 and the tracking control means 11. The position of the light beam spot S is changed by moving the optical head 15. Then, when the RF amplitude increases, the process returns to step 5 and further supplies an offset correction voltage to the first adding means 8 on the negative side.

In step 7, when the offset correction voltage is supplied to the negative side, the RF amplitude does not increase. When it is determined that the maximum value of the RF amplitude is on the negative side of the offset correction voltage, the process proceeds to step 8. By supplying the offset correction voltage with the maximum RF amplitude to the first adding means 8, the position of the light beam spot S can be moved and the light beam spot S can be traced to the center of the groove G2. .

(Land pre-pits p11, p12, p1
3, where p22 and p23 are entirely formed in the center of the lands L1 and L2). Similarly to the above, in step 1, the light receiving signals A and B input from the two-divided light receiving portion of the photodetector 4 are output. TE offset calibration means 7 based on the sum signal
Monitor the RF amplitude when the offset correction voltage output from is 0 V. In this case, the result of executing Step 2, Step 3, Step 4, Step 5, Step 6, and Step 7 is that the light beam spot S
2, the information recording mark recorded in the central part of the groove G2 is detected, and the RF amplitude of the RF signal detected from this information recording mark becomes the maximum. For this reason, the light beam spot S can be traced to the center of the groove G2 by keeping the state without supplying the offset correction voltage to the first adding means 8.

As described above, according to the configuration of the embodiment of the present invention, the optical disk is utilized by utilizing the fact that the state where the light beam spot S traces the center of the groove G2 gives the maximum value of the RF amplitude. Even when the land prepits p11, p12, p13, p22, and p23 are formed unevenly on the inner peripheral side or outer peripheral side of the information recording mark 1, the information recording mark recorded in the center part of the groove G2 by the TE offset calibration means 7. The offset correction voltage is output so that the RF amplitude of the RF signal detected from the optical beam spot becomes the maximum value, and the position control of the light beam spot S is performed.
Can be traced to the center of the groove G2.

The land pre-pits p11, p12,
When p13, p22, and p23 are formed at the center of the land, the state where the light beam spot S traces at the center of the groove G2 gives the maximum value of the RF amplitude. After that, the light beam spot S can be traced to the center of the groove G2 by keeping the offset correction voltage as it is without supplying it to the first adding means 8.

[0050]

According to the present invention, since the TE offset calibration means is provided, the light beam spot S is
Land pre-pits are formed on the inner or outer circumference of the optical disc by using the fact that the RF amplitude of the RF signal detected from the information recording mark recorded at the center of the optical disc 2 gives the maximum value. In this case, the offset correction voltage at which the RF amplitude becomes the maximum value is output from the TE offset calibrating means to control the position of the light beam spot, and the position of the light beam spot is accurately controlled at the center of the information recording track. Can be done.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram showing grooves and land prepits on an optical disk used in the optical disk device according to the embodiment of the present invention.

FIG. 3 is a schematic diagram of a zone arrangement in an optical disk used in the optical disk device of the embodiment of the present invention.

FIG. 4 is a diagram showing a specific arrangement of grooves and land prepits on an optical disk used in the optical disk device of the embodiment of the present invention.

FIG. 5 is a block diagram of a second track deviation detecting means in the optical disk device of the present invention.

FIG. 6 is a block diagram of a TE offset calibration unit in the optical disc device of the present invention.

FIG. 7 is a timing chart for explaining the operation of the optical disc device of the present invention.

FIG. 8 is a diagram conceptually showing a portion of a conventional optical disk in which adjacent wobble phases have opposite phases.

FIG. 9 is a diagram showing a tracking shift detection signal in a case where wobbles have the same phase between adjacent grooves and a land prepit formed on a land between the grooves is located at the center of the land.

FIG. 10 is a diagram showing a tracking shift detection signal in a case where wobbles have the same phase between adjacent grooves, and land prepits formed on lands between the grooves are more deviated toward the outer peripheral side of the disc than the center of the land. is there.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Spindle motor, 3 ... Light source, 4
.., Photodetector, 5... First track shift detecting means, 6... Second track shift detecting means, 7... TE offset calibrating means, 8... First adding means, 9.
Moving means, 11: tracking control means, 12: wobble signal detecting means, 13: reference clock generating means, 14 ...
Motor control means, 15: optical head, 61: first auxiliary information detection unit, 62: second auxiliary information detection means, 63: first
High-pass filter (first HPF), 64... Second high-pass filter (second HPF), 65... First holding means, 66... Second holding means, 67. …
Subtraction means, 69 low-pass means, 71 RF detection means,
72: sample and hold means, 73: ADC (analog / digital conversion means), 74: DSP (digital signal processor), 75: DAC (digital / analog conversion means)

Claims (2)

[Claims] 1. A groove formed concentrically or helically from the innermost circumference to the outermost circumference and having an information recording mark recorded at the center thereof, and is continuously formed between the groove grooves. A land portion, and the land portion has an auxiliary information recording area in which auxiliary information used for recording or reproducing an information signal in the groove is previously recorded as a land pre-pit, The land portion is divided in advance into a plurality of zones in the radial direction of the disk, and the groove is continuously wobbled with a constant frequency on both sides of the groove in the circumferential direction of the disk, and The phases of the wobbles of the groove adjacent to each other in the radial direction of the disk are the same, and a plurality of wobbles arranged in the land portion every period of the wobble A pre-pit group consisting of land pre-pits is irradiated with a light beam spot from a light source to an optical disc recorded at a position in the disc radial direction where adjacent phases have different phases in the disc circumferential direction. An optical disc device for recording or reproducing an information signal by dividing a reflected light of a light beam spot applied to the groove by at least two by a dividing line optically substantially parallel to a tangential direction of the groove of the optical disc. A photodetector that receives light at the divided light receiving unit, and a displacement between the light beam spot and the groove groove based on a difference signal between light receiving signals respectively output from the divided light receiving units of the photodetector. And a first track shift detection signal for causing the light beam spot to follow the groove groove. A first track shift detecting unit for generating a signal, and a wobble signal is detected by extracting a frequency component of the wobble based on a difference signal of a light receiving signal output from each of the divided light receiving units of the photodetector. A wobble signal detection unit, a wobble signal output from the wobble signal detection unit, and a light reception signal output from each of the divided light receiving units of the photodetector, and an inner peripheral land preamble based on the wobble signal. A second track shift detecting unit that generates a second track shift detection signal indicating a shift of the light beam spot from a central portion of the groove groove from a difference value between the pit signal and the outer peripheral side land pre-pit signal; The amplitude of the RF signal detected from the information recording mark is minimized based on the sum signal of the received light signals output from the divided light receiving sections of the photodetector. TE offset calibrating means for generating an offset correction voltage such that the following is obtained: tracking obtained by combining the first track deviation detection signal with a signal obtained by adding the second track deviation detection signal and the offset correction voltage By the error signal, the position of the light beam spot of the light beam spot on the optical disk is controlled to move in the groove groove width direction,
Spot position control means for tracing the light beam spot at the center of the groove, and the optical disc is placed in at least the same zone among the plurality of zones based on a wobble signal and a reference clock from the wobble signal detection means. An optical disk rotating means for rotating the optical disk at the same number of revolutions. 2. The method according to claim 1, wherein said TE offset calibration means generates an RF signal based on a sum signal of a reception signal of said information recording mark detected by a divided light receiving section of said photodetector.
F detecting means, sample and hold means for detecting and sampling and holding the RF amplitude of the RF signal, analog-to-digital conversion means for digitizing the sampled and held RF amplitude, and the RF amplitude having a maximum value. 2. The optical disk apparatus according to claim 1, further comprising a digital signal processor for outputting the offset correction voltage, and digital-to-analog converting means for converting the offset correction voltage into an analog signal.