JP2998587B2 - Optical disk drive - Google Patents

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,
2. Description of the Related Art In an optical disk drive for recording / reproducing information on a magneto-optical disk, a phase-change disk, or a dye-type disk on which a groove is formed, recording / reproducing is performed on a disk in which only one side wall of the groove is wobbled. When performing reproduction, high-precision tracking error (TE) signal and wobbling carrier (WobC) by two beam method
Signal and time / address (ADD) signal,
The present invention relates to an apparatus capable of simultaneously recording / reproducing two systems of information as a two-beam system recording / reproducing system.

[0002]

2. Description of the Related Art Along with the widespread use of CDs (Compact Discs), which are optical disks exclusively for audio reproduction, recently, MDs (Mini Diodes) which are magneto-optical disks capable of recording / reproducing.
Sc) and phase change (PC) disks are in the limelight, and various disk devices have been developed. In general, in recording / reproduction for a disk, it is necessary to detect tracking, linear velocity control information, and time / ADD information, and various methods are adopted according to the type of the disk.

[0003] First, in a CD, all the recorded information is recorded in the form of pits formed as irregularities on a reflection surface, and the control information and time / ADD information are also detected using the pits. You. More specifically, regarding the tracking operation, a focused spot (main spot) for reading recorded information on a CD and two spots irradiated on both sides thereof
A three-beam system in which two condensed spots (side spots) are provided and the reflected light of each side spot is detected and used as a TE signal, or only one condensed spot (main spot) is used and the reflected light is disc A one-beam push-pull system is adopted in which light is received by a photodetector divided into two in a direction parallel to the linear velocity direction, and tracking control is performed so that the received light intensity in the divided areas becomes equal.

On the other hand, MD and CD-MO (Magneto-Optical)
On recordable discs such as PCs and PC discs, there may be cases where recorded information does not exist in tracks or the recorded information has been erased. Grooves (guide grooves) are often formed in a meandering manner. For example, in MD, FIG.
As shown in (A) [enlarged plan view of the disk] and (B) [sectional view taken along the arrow XX of (A)], grooves 61 and lands 62 meandering along the circumferential direction of the disk are alternately formed. Groove 61 in which recorded information is formed with a width wider than land 62.
Is subjected to magneto-optical recording. Here, the side wall 63 formed between the groove 61 and the land 62 is wobbled at a constant period, and both side walls facing each other via the groove 61 are formed.
63 have the same wobbling cycle. However, FIG.
As shown in (A), when the track (groove 61) is different, the phase of the wobbling waveform is different.

[0005] When recording / reproducing an MD, a method of obtaining a reproduction signal and various control signals based on the configuration shown in FIG. 7 is adopted. First, three condensed spots B0, B1, and B2 are irradiated on the disc at regular intervals in the linear velocity direction and the radial direction of the disc, and reflected beams from the respective condensed spots B0, B1, and B2 are irradiated on the disc. The beam is divided into 9 beams by the Wollaston prism 71,
Five of the beams are received by the photodetector. Specifically, the reflected beam relating to the central condensed spot B0 is separated into three beams by a three-beam Wollaston prism 71, and the respective beams are separated by photodetectors 72, 73, 74 (however, the photodetectors 72 is a four-split type), and the reflected beams related to the front and rear focus spots B1 and B2 are also reflected by the prism 71, respectively.
Are separated into three beams, but only one of each of the three beams is guided to the photodetectors 75 and 76 as a target beam.

In the reproducing mode, a magneto-optical disk for recording is used.
(Recordable MD) and the read-only optical disk (premastered MD) have different RF signal detection methods. In the case of recordable MD, the RF signal is separated by the prism 71 and guided to the photodetectors 73 and 74. In the case of pre-mastered MD, the beams B0P and B0S of the mutually orthogonal polarization components are used, and the differential signal of the output signal of each photodetector 73 and 74 is obtained by the differential amplifier 81 to obtain an RF signal (MO). The sum signal of the output signals of the photodetectors 73 and 74 is obtained by the summing amplifier 82 to obtain the RF signal (PIT).
And Naturally, the RF signal (MO) corresponds to the polarization rotation of the reflected light related to the focused spot B0, and the RF signal (P
IT) corresponds to a change in the amount of reflected light related to the condensing spot B0. Each control signal is detected by the following method. The focus error (FE) signal is obtained based on the so-called astigmatism method, and the arithmetic unit 83 obtains a difference signal between the sums of the signals obtained from the diagonal regions of the quadrant photodetector 72. The TE signal focuses the side spots on the focused spots B1, B2.
The difference signal between the output signals of the photodetectors 75 and 76 corresponding to the condensed spots B1 and B2 is obtained by the differential amplifier 84. For the WobC signal, the arithmetic unit 85 obtains the difference signal between the sum of the signals obtained from the respective regions sandwiching the division line parallel to the linear velocity direction of the disk in the photodetector 72, and further sets the center of the pass band to the wobbling frequency. Bandpass filter
(BPF) 86 is obtained by detecting a modulated signal due to wobbling. For the ADD signal, WobC
The signal is obtained by demodulating the signal with the FM demodulator 87 and decoding with the decoder 88. On the other hand, in the recording mode, recording is performed by applying a magnetic field in the magnetization direction corresponding to the recording information to the area of the converging spot B0 while performing the servo control using the control signals described above.

[0007]

In the conventional three-beam system for tracking control including the recording and reproduction system for the MD, two beams are required in addition to the main signal reproduction, and the efficiency is low in view of the hardware configuration. When applied to a PC disk or CD-WO, an offset occurs in the TE signal between a track on which information is written and a track on which information is not written. Also in the one-beam push-pull method, if the objective lens shifts in principle, an offset occurs in the TE signal, and various measures are required to reduce the offset ("optical disc technology", radio technology Company,
Published February 10, 1989, P87-P97).

On the other hand, as a deformed disk relating to wobbling, as shown in FIG. 8, "only one side wall 1a of the groove 1 is meandering, and the average value of the width of the groove 1 is the land 2 between the grooves 1. An optical disk characterized by being set to be equal to the average value of the width ”has been proposed (Japanese Patent Laid-Open No. 5-314538). According to this optical disk, due to the above-mentioned features, as shown in FIG.
When 02 is irradiated, a strong tracking signal is obtained, and accurate tracking / spindle control and the like can be performed.

Further, as a recent attempt for high-density recording on an optical disk, land / groove recording, that is, a method of recording data on both lands and grooves, has been proposed (Ohno et al .: “Land & groove on phase change optical disks”). Study of Groove Recording ", Proceedings of the Spring Meeting of the Japan Society of Applied Physics 29a-B-9, '93, suggesting the possibility of high-density recording without shortening the light source or improving NA (Numerical Aperture) of the objective lens. Attention has been paid to the one-sided wobbling type optical disk (FIG. 8) according to the above proposal in performing land and groove recording. That is, in the optical disk of the one-side wobbling method, it is possible to obtain a stronger TE signal as compared with the case where the two-side wobbling is performed like MD, and it is possible for one light spot to simultaneously hit two meandering side walls. Therefore, land and groove recording can be performed with high accuracy by accurate tracking control and address information detection based on the above features.

Therefore, the present invention makes it possible to detect various control signals with high accuracy by a two-beam method for the above-mentioned optical disk in which only one side wall of the groove is wobbled. It was created for the purpose of providing an optical disc device which enables simultaneous recording and reproduction of two systems of information on a land and a groove by a two-beam system using the above-mentioned method.

[0011]

According to a first aspect of the present invention, information is recorded on an optical disk in which a groove is formed and only one of the inner and outer side walls of the groove is wobbled. And / or an optical disc device for performing reproduction, a light irradiating means for independently irradiating a converging spot on a region including the wobbling portion on a groove surface and a land surface adjacent via a wobbling side wall; Two light detecting means for independently detecting and photoelectrically converting each reflected light from each of the condensed spots, and two light extracting means for extracting the amplitude of the modulation component based on the wobbling in the output signal of each of the light detecting means. An amplitude extractor; and a signal calculator for calculating a difference or a sum of the amplitude signals extracted by the respective amplitude extractors. A difference signal or the sum signal according to the optical disk apparatus characterized by using as a TE signal.

According to a second aspect of the present invention, in the optical disk apparatus of the first aspect, the light irradiating means irradiates the two condensed spots at a constant interval in the linear velocity direction of the optical disk, and irradiates the light with respect to the linear velocity direction of the optical disk. Delay means for giving the output signal of the light detection means for detecting the reflected light of the converging spot to be radiated a delay corresponding to a time obtained by dividing the interval between the condensing spots by the linear velocity of the optical disc, and outputting the signal; Signal calculating means for obtaining a difference signal or a sum signal between an output signal of a light detecting means for detecting reflected light of a condensed spot irradiated later with respect to a linear velocity direction of the optical disc and a delay output signal of the delay means; The present invention relates to an optical disc device that obtains a WobC signal and / or an ADD signal based on a difference signal or a sum signal obtained by a calculation means.

According to a third aspect of the present invention, in the first or second aspect, in the recording mode, the irradiation intensity of each condensed spot irradiated by the light irradiating means is modulated by two systems of recording signals, thereby forming a groove. The present invention relates to an optical disc device that performs simultaneous recording of two systems on a surface and a land surface and, in a reproduction mode, simultaneously reproduces two systems of signals from output signals of the respective photodetectors.

[0014]

[Action]

Regarding the first invention; the present invention is for an optical disc in which only one side wall of a groove is wobbled, and detects a TE signal by a two-beam method. Since the two condensed spots are independently irradiated on the area including the wobbling portion on the adjacent groove surface and land surface,
A modulation signal based on wobbling is obtained from each light detecting means by the rotation of the optical disc, and if the amplitude of each modulation signal is detected by each amplitude extracting means, each amplitude signal is condensed in a direction perpendicular to the track. The size changes according to the movement of the spot.

When each of the condensed spots is irradiated near the wobbling of the optical disk, the magnitude of each of the amplitude signals changes in the same or opposite directions. Therefore, when a difference signal or a sum signal of each amplitude signal is obtained by the signal calculation means, the difference signal or the sum signal is quantitatively indicated, so that tracking control can be performed using the difference signal or the sum signal. Note that whether the signal calculation means obtains the difference signal or the sum signal depends on the optical conditions of the optical disk (for example,
(Groove depth, relative ratio of groove width to land width, etc.)
The appropriate one is selected according to.

Regarding the second invention; generally, when recording / reproducing is performed on an optical disk on which a wobbling groove is formed, a WobC signal or an ADD signal is created based on a modulation signal obtained from a wobbling unit. I do. The present invention detects a WobC signal and / or an ADD signal by a two-beam method for a one-side wobbling optical disk as in the first invention. Use output signal.

In the first aspect of the present invention, the condensed spots are arranged at regular intervals in the linear velocity direction of the disk, and the modulation signal of each light detecting means based on wobbling is the same as that of the condensed spot. The phases are different by the time obtained by dividing the interval by the linear velocity of the optical disk. Therefore, the output signal of the light detection means corresponding to the condensed spot irradiated in advance in the linear velocity direction of the disk is delayed by the time by the delay means, and the signal delayed by the signal calculation means and the subsequent irradiation A modulation signal based on wobbling is obtained by obtaining a difference signal or a sum signal of the output signals of the light detection means corresponding to the converging spot. Whether the signal operation means obtains the difference signal or the sum signal is determined by the same conditions as in the first embodiment. In the present invention, the entrance pupil of the reflected light in each light detecting means is divided into two parts in a direction parallel to the linear velocity direction of the optical disk, and a difference signal between the photoelectric conversion signals in each of the divided areas is obtained by a difference calculating means. If output is performed, the detection sensitivity of the wobbling modulation component can be improved.

According to a third aspect of the present invention, in the first or second aspect, each condensed spot irradiated by the light irradiating means is irradiated on the groove surface and the land surface on both sides including the wobbling portion of the side wall. Become. This means that two types of recording information are recorded simultaneously on the groove and land,
It also suggests that the recorded information can be reproduced simultaneously.

Therefore, in the present invention, in the recording mode, recording is performed by modulating the irradiation intensity of each condensed spot with a recording signal, and in the reproduction mode, the signal is reproduced from the output signal of each light detecting means. -Simultaneous recording and reproduction of two systems on the land are realized. That is, high-density recording by land & groove recording is enabled while detecting various control signals by the two-beam method as described above.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the optical disk apparatus according to the present invention will be described below in detail with reference to FIGS. The optical disk used in each of the embodiments has wobbling applied to only one side wall 1a of the groove 1 as described with reference to FIG. 8, so that the average value of the width of the groove 1 and the average value of the width of the land 2 are obtained. Are set to be substantially equal to each other.

<< Embodiment 1 >> This embodiment relates to an apparatus for detecting a TE signal from an optical disk of the one-side wobbling method. First, FIG. 1 shows the size and positional relationship of the condensed spots B1 and B2 on the optical disc in this embodiment, and shows a TE signal detection circuit. Focusing spot B1, B
Reference numeral 2 denotes a laser beam emitted from two laser beam emitting portions fixed on the pickup unit to the surface of the optical disk via an optical system. As shown in FIG. 1, the optical pickup is accurately tracked. In the state where
The centers of the condensed spots B1 and B2 are located on the groove 1 side and the land 2 side adjacent to each other via the side wall 1a.

In this embodiment, each converging spot B1, B2
The reflected light of each of the optical detectors 3, 4
The respective photoelectric conversion outputs of the respective photodetectors 3 and 4 are input to the respective BPFs 5 and 6 whose passband centers are set to the wobbling frequency of the side wall 1a, and the respective wobbling modulation signals obtained from the respective BPFs 5 and 6 Is input to each ENV detection circuit 7, 8 to extract the amplitude component of the wobbling modulation signal. Further, each amplitude signal output from each ENV detection circuit 7, 8 is input to the differential amplifier 9, and the differential A difference signal between the amplitude signals output from the amplifier 9 is defined as a TE signal. As described above, the optical system for irradiating the optical disc with the converging spots B1 and B2 and detecting the reflected light can be realized by the configuration as shown in FIG. That is, a straight line connecting the laser beam emitting units 11 and 12 with the semiconductor laser unit 13 in which the two laser beam emitting units 11 and 12 are arranged at a fixed interval is formed on the optical disk 14.
Each laser beam emitted from each of the laser beam emitting units 11 and 12 and transmitted through the beam splitter 15 is attached to the objective lens 16.
And irradiate them as condensed spots B1 and B2 on the adjacent groove 1 and land 2 of the optical disk 14. On the other hand, the reflected light from each of the condensing spots B1 and B2 is
The light is converged at 6, is reflected by the reflection surface of the beam splitter 15, and is incident on each of the photodetectors 3, 4.

Next, the principle of detecting the TE signal will be described. First, the BPFs 5 and 6 detect wobbling modulation components from the output signals of the photodetectors 3 and 4, and the amplitude signals of the output signals are extracted by the ENV detection circuits 7 and 8, respectively. When each of the condensed spots B1, B2 is located at the position in the correct tracking state as shown in FIG.
Since the amplitude levels of the wobbling modulation components obtained from 2 are the same, the output signal (TE signal) of the differential amplifier 9 indicates 0. However, when the positions of the condensed spots B1, B2 deviate from the above-mentioned normal positions (in an erroneous tracking state), the amount of reflected light obtained from the wobbling portion of each of the condensed spots B1, B2 changes reciprocally. Correspondingly, the respective amplitude levels also change reciprocally, so that the differential amplifier
The difference signal of each amplitude signal level can be detected as a TE signal by 9.

More specifically, for example, as shown in FIG. 2A, the positions of the condensed light spots B1 and B2 change from a correct tracking state shown by a solid line to an error state shown by a two-dot chain line. When it moves, the area of the wobbling portion of the converging spot B1 becomes smaller,
The area over the wobbling portion 2 becomes larger. Accordingly, the wobbling modulation component included in the output signal of each photodetector 3 decreases, and the component obtained from the photodetector 4 increases, and the amplitude signal level obtained from the ENV detection circuit 7 naturally decreases. However, since the level of the amplitude signal obtained from the ENV detection circuit 8 increases, the output signal of the differential amplifier 9 that detects them differentially decreases.

When each of the condensed spots B1, B2 is moved in the form of a track jump, each of the condensed spots B1, B2 is moved.
The respective amplitude signal levels corresponding to B2 are represented by S1 in FIG.
And S2, and the output signal of the differential amplifier 9 for obtaining the difference signal (S1-S2) between the respective amplitude signals changes with respect to the moving direction as shown in FIG. Will be presented. Therefore, in the case of this embodiment, the output of the differential amplifier 9 becomes 0 when each of the condensed spots B1 and B2 is at a normal position, but TE occurs and the position of each of the condensed spots B1 and B2 is changed. Moving to the position indicated by the two-dot chain line in FIG. 2A, the output of the differential amplifier 9 becomes -ΔE, and the TE amount can be quantitatively detected from the change value of the output signal.

By the way, the two-beam system of this embodiment is
Assuming a case where the present invention is applied to a disk with double-sided wobbling as shown in FIG.
The center of B2 is set at an interval (an interval in a direction perpendicular to the linear velocity direction of the disk) such that the center of B2 is located on the groove side and the land side on both sides of the wobbling portion, and each of the condensing spots B1, B2
Is moved, the period of the change of each amplitude signal corresponding to each of the condensed spots B1 and B2 becomes 倍 times that of the present embodiment, and naturally the period is 1 even if the difference or the sum of each amplitude signal is obtained. / 2
Double. Therefore, the change tendency of the difference signal and the sum signal is such that the converging spot B1 is on the groove side, the converging spot B2 is on the land side, the converging spot B1 is on the land side, and the converging spot B2 is The state is the same as the state where the light is irradiated on the groove side, and the two states correspond to one change tendency, so that the state cannot be used as the TE signal. In other words, this embodiment provides an effective TE signal detecting means by targeting only the optical disk in which only one side wall of the groove is wobbled.

In this embodiment, a single entrance pupil is used as each of the photodetectors 3 and 4. As shown in FIG. 4, the entrance pupil divided into two in the direction parallel to the track direction is used. The differential signal of each photoelectric conversion output corresponding to each entrance pupil may be obtained by each of the differential amplifiers 21 and 22 using the photodetectors 3a and 4a provided. In that case, each wobbling modulation signal is obtained with a large amplitude, and accurate detection of the TE signal becomes possible.

In this embodiment, since the amplitude signal is extracted from only the wobbling modulation signal corresponding to each of the condensed spots B1 and B2 and the difference signal is obtained by the two-beam method, the information has already been written. An offset does not occur between the track and the unwritten track, and even if there is a cause for causing an offset in the optical system, the offset is canceled.

Embodiment 2 This embodiment relates to an apparatus for detecting a WobC signal and an ADD signal from a one-side wobbling optical disk. The WobC signal and the ADD signal are created based on the wobbling modulation signal of the optical disc, and the optical disc apparatus executes rough servo control of a spindle motor for rotating the optical disc using the WobC signal, and performs AD control.
Using the D signal, an absolute position on the disk required for cueing information or the like is detected.

The circuit for detecting the two signals in this embodiment is shown in FIG. 5, and as shown in FIG.
In the case where 3a and 4a are used, it is necessary to input the outputs of the differential amplifiers 21 and 22 to the BPFs 5 and 6 whose passband centers are set to the wobbling frequency of the side wall 1a to detect the wobbling modulation signal. This is the same as the circuit configuration for detecting the TE signal in Example 1.

By the way, as described in the first embodiment,
Since the condensed spots B1 and B2 are formed at regular intervals in the linear velocity direction of the optical disc, the wobbling modulation signals output from the BPFs 5 and 6 are out of phase.
That is, the linear velocity of an optical disk driven by a CLV (Constant Linear Velocity) method is represented by V, and each condensing spot B1,
When the separation interval in the linear velocity direction of B2 is L,
The wobbling modulation signal corresponding to the converging spot B1 to be irradiated earlier appears with a phase advanced by the time τ (= L / V) from the wobbling modulation signal corresponding to the condensing spot B2 to be irradiated later.

Therefore, in this embodiment, the light spot B
A delay circuit 23 for delaying the wobbling modulation signal corresponding to 1 by a time τ is provided to match the phases of both wobbling modulation signals, and the respective wobbling modulation signals whose phases match are input to an addition amplifier 24, A WobC signal having a large amplitude is obtained from the 24 outputs. The ADD signal is obtained by demodulating the output signal of the addition amplifier 24 with the FM demodulator 25 and decoding the demodulated signal with the decoder 26.

Embodiment 3 This embodiment relates to an apparatus for simultaneously recording / reproducing two systems of information for a groove 1 and a land 2 of a one-sided wobbling optical disk. In the first and second embodiments, each of the condensed spots B1 and B2 is used for detecting various control signals. Naturally, a condensed spot for recording / reproduction is separately provided, and the groove 1 is used while using the control signal. Alternatively, it is possible to record information on the land 2 and to reproduce the information. However, as shown in FIGS. 1, 2, 4 and 5, each of the condensed spots B1 and B2 includes a wobbling portion. The grooves 1 and lands 2 are irradiated.

Therefore, if the irradiation intensity of each of the condensed spots B1 and B2 is modulated by the recording information, it is possible to record two systems of information on the groove 1 and the land 2 at the same time. It becomes possible to read and reproduce the information of two systems recorded in 2. Further, the recording / reproducing operation can be performed while executing the tracking spindle servo and the address management by detecting the control signal according to the first and second embodiments. That is, when an optical disk of the one-side wobbling method is used, simultaneous recording and simultaneous reproduction of two systems of information can be realized for the groove 1 and the land 2 while obtaining various control signals by the two-beam method.

FIG. 6 shows the configuration of the reproduction circuit of this embodiment together with the detection circuits of the respective control signals in the first and second embodiments. In the figure, components using the same reference numerals as those used in FIGS. 4 and 5 indicate the same circuit elements and the like, and detailed description thereof will be omitted here. However, the differential amplifiers 21 and 22 and the BPFs 5 and 6, which detect the wobbling modulation component from the outputs of the photodetectors 3a and 4a, have a circuit configuration shared by the TE signal detection system and the WobC signal / ADD signal detection system. ing.

The reproducing circuit according to this embodiment uses the divided outputs of the photodetectors 3a and 4a divided into two parts by the addition amplifiers 29 and
The addition at 30 yields two reproduction signals RF1 and RF2. That is, in the reproduction mode, the information recorded in the groove 1 is reproduced from the condensed spot B1 and the reproduced signal RF1 is collected again while the accurate tracking control and the spindle control are performed by the detection circuit of each control signal. The information recorded on the land 2 is reproduced from the spot B2 to obtain a reproduction signal RF2. In this case, the RF signals 1 and 2 include a wobbling modulation component, but the recording signals of the grooves 1 and the lands 2 have a much higher frequency than the wobbling frequency. The wobbling modulation component can be easily removed.

On the other hand, in the recording mode, the intensity of each laser light emitted from the laser beam emitting units 11 and 12 shown in FIG. Are modulated by the two sets of recording information, and recording is performed on the land 1 and the groove 2 by changing the irradiation intensity of each of the condensed spots B1 and B2.

In that case, the differential amplifier in the circuit of FIG.
Modulation components corresponding to each recording information appear on the outputs of 21, 22. However, since only wobbling modulation components are detected in BPF5, 6, there is no problem in detecting each control signal. Recording of information can be realized while performing control and the like.

[0039]

According to the optical disk device of the present invention having the above configuration, the following effects can be obtained. The invention according to claim 1 is an optical disc apparatus for recording and / or reproducing information on an optical disc in which only one of the inner and outer side walls of the groove is wobbled. The area including the wobbling portion on the groove surface and the land surface to be irradiated is independently irradiated with two condensed spots, and the TE signal is obtained by using the amplitude change of the wobbling modulation component detected from each condensed spot. , A TE signal in which no offset occurs regardless of the writing state of the track is obtained,
Further, according to the configuration, since recording and / or reproduction can be performed using one or both of the condensed spots, it is possible to detect the TE signal by the two-beam system more efficiently than the conventional three-beam system. The invention of claim 2 improves the detection sensitivity of the wobbling modulation component in the invention of claim 1 and enables more accurate detection of the TE signal. Claim 3
In parallel with the detection of the TE signal, the invention of
This makes it possible to detect the WobC signal and the ADD signal at a high precision with a / N ratio. The invention according to claim 4 is directed to the one-sided wobbling type optical disc as claimed in claims 1 to 3.
According to the invention of the present invention, two kinds of recording information are simultaneously recorded on the groove and the land of the optical disk while detecting various control signals and executing accurate tracking spindle servo control, etc., and simultaneously recording the two kinds of recording information. It enables reproduction, and realizes high-density recording on an optical disk without shortening the wavelength of a light source or improving the NA of an objective lens.

[Brief description of the drawings]

FIG. 1 relates to Embodiment 1 of an optical disk device of the present invention, and shows a positional relationship between respective condensed spots on an optical disk [(A) is an enlarged plan view of the disk, and (B) is a cross-sectional view taken along the arrow XX of (A)]. , And T
FIG. 3 is a diagram illustrating a detection circuit of an E signal.

FIG. 2 is a diagram showing a positional relationship (A) between respective condensing spots on an optical disk.
And a graph showing a change of each amplitude signal extracted from the wobbling modulation signal with respect to a movement amount of each converging spot.
5B is a graph illustrating a change in the difference signal between the amplitude signals, and FIG.

FIG. 3 is a diagram showing a configuration of an optical system that irradiates each condensed spot onto an optical disc and detects reflected light thereof.

FIG. 4 is a diagram showing a positional relationship between respective condensed spots on an optical disc and a TE signal detection circuit in the case of using a photodetector having an entrance pupil divided into two parts according to the first embodiment.

FIG. 5 is a diagram illustrating a positional relationship between respective condensed spots on an optical disc and a detection circuit for a WobC signal and an ADD signal according to the second embodiment.

FIG. 6 relates to Example 3 in the case of reproducing the positional relationship between the condensed spots on the optical disc, the detection circuit for the TE signal, the WobC signal, and the ADD signal, and the two systems of recorded information recorded in the groove and the land. FIG. 3 is a diagram illustrating a detection circuit of a reproduction signal.

FIG. 7 relates to a conventional MD disk device.
The position of the condensed spot on the disk [(A) is an enlarged plan view of the disk, (B) is a cross-sectional view taken along the line XX of (A)], a reproduction signal detection circuit, and the FE signal, TE signal, WobC signal, ADD
FIG. 3 is a diagram illustrating a signal detection circuit.

FIG. 8 shows a configuration of an optical disk of a one-side wobbling method,
FIG. 3A is a diagram showing a position of a condensed spot [(A) is an enlarged plan view of a disk, and (B) is a cross-sectional view taken along the line XX of (A)].

[Explanation of symbols]

1,61… groove, 1a, 63… side wall with wobbling, 2,62… land, 3,3a, 4,4a, 72,73,74,75,76… photodetector (light detection means), 5,6,86 ... BPF (5,6; amplitude extraction means),
7,8 ... ENV circuit (7,8; amplitude extraction means), 9,21,22,81,84 ...
Differential amplifier (9; signal operation means, 21, 22; difference operation means), 1
1,12 laser beam emitting unit, 13 semiconductor laser unit, 14 optical disk, 15 beam splitter, 16 objective lens, 23 delay circuit (delay means), 24, 29, 30, 82 82 summing amplifier (24 ; Signal operation means), 25,87 ... FM demodulator, 26,88
… Decoder, 71… 3 beam Wollaston prism, 83,
85: arithmetic unit, B0, B01, B02, B1, B2: condensed spot (irradiated by light irradiating means), -ΔE: output of differential amplifier 9,
L: separation distance between the condensing spots B1, B2, S1, S2: amplitude signal, V: linear velocity of the optical disk, τ: advance phase time of the wobbling modulation signal.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 7/09-7/10 JICST file (JOIS) WPI (DIALOG)

Claims (4)

(57) [Claims] 1. An optical disc apparatus for recording and / or reproducing information on an optical disc in which a groove is formed and wobbling is applied only to one of an inner peripheral side and an outer peripheral side wall of the groove. Light irradiating means for independently irradiating a converging spot on a region including the wobbling portion on a groove surface and a land surface adjacent to each other via a side wall subjected to wobbling,
Two light detecting means for independently detecting and photoelectrically converting each reflected light from each of the condensed spots, and two light extracting means for extracting the amplitude of the modulation component based on the wobbling in the output signal of each of the light detecting means. Amplitude extracting means, and signal calculating means for calculating a difference or a sum of the respective amplitude signals extracted by the respective amplitude extracting means, wherein the difference signal or the sum signal obtained by the signal calculating means is used as a tracking error signal. An optical disk device that was characterized. 2. An entrance pupil of reflected light in each light detecting means is divided into two in a direction parallel to a linear velocity direction of the optical disk, and a difference signal between photoelectric conversion signals in each of the divided areas is obtained by a difference calculating means. 2. The optical disk device according to claim 1, wherein the optical disk device outputs the data. 3. A light irradiating means irradiates the two converging spots at a constant interval in the linear velocity direction of the optical disk, and detects reflected light of the converging spot previously irradiated in the linear velocity direction of the optical disc. A delay means for giving an output signal of the light detection means a delay corresponding to a time obtained by dividing the interval between the respective condensed spots by the linear velocity of the optical disc, and outputting the delayed light; Signal calculating means for obtaining a difference signal or a sum signal between the output signal of the light detecting means for detecting the reflected light of the spot and the delay output signal of the delay means, and based on the difference signal or the sum signal obtained by the signal calculating means. 3. The optical disk device according to claim 1, wherein a wobbling carrier signal and / or an address signal are obtained. 4. In the recording mode, the irradiation intensity of each condensed spot irradiated by the light irradiation means is modulated by two types of recording signals to thereby control the groove surface and the land surface.
4. The optical disk apparatus according to claim 1, wherein simultaneous recording is performed in two systems, and in a reproduction mode, signals of two systems are simultaneously reproduced from output signals of the respective light detecting means.