JP2800701B2 - Optical recording medium recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recording / reproducing an optical recording medium.

[0002]

2. Description of the Related Art With the increasing demand for recording various information signals at a high recording density, in recent years, high-density recording of information signals has been achieved by using information recording media made based on various constitutional principles and operating principles. Reproduction is performed. For example, magnetic recording according to an information signal is performed on a ferromagnetic recording layer of an information recording medium, or recording and reproduction is performed by optical means using a magneto-optical recording medium. Or, for example, it is already practical to record the information signal by forming irregularities corresponding to the information signal on the information signal surface of the information recording medium and to reproduce the recorded information signal by optical means. In addition, in order to meet the demand for high-density recording and reproduction in various technical fields, the recording layer of the information recording medium is irradiated with a beam whose intensity is modulated by an information signal. Thus, information recording media in which information signals are recorded by causing a physical change or a chemical change in the recording layer of the information recording medium in accordance with the information signal have come into practical use. .

[0003] As semiconductor lasers that operate stably can be easily obtained, various types of optical recording media (hereinafter, referred to as optical discs) capable of performing high-density recording and reproduction using laser light. (May be described)
However, since it is possible to perform recording and reproduction in a non-contact state, it is resistant to scratches and dust, and has the advantage that a large storage capacity can be obtained by high-density recording.
It is also well known that research and development for practical use is being carried out, and it is well known that pits formed as geometric concave or convex portions reproduce a large amount of information signals from a master on which information signals are recorded. Compacted optical discs (playback-only optical discs)
In addition to the widespread use of disks, rewritable optical disks, such as magneto-optical disks and other optical disks,
For example, it has been put to practical use in office file memories and other uses.

When recording information is recorded as digital data on an optical disc, the recording and reproducing efficiency is high and a good recording and reproducing operation can be obtained in conformity with the characteristics of the recording system and the characteristics of the reproducing system. In order to achieve this, a sequential channel word formed by channel bits obtained by converting a data word to be recorded / reproduced according to a predetermined modulation method is applied to an optical disc by applying a recording method such as a mark length recording method or an inter-mark recording method. It is well known that recording has been widely performed in the past. For example, in a compact disc (CD) widely known as the already-recorded optical disc (optical disc for reproduction only) described above. Represents a first data word to be recorded and reproduced by a so-called E
Recording information is recorded on a signal surface by applying a mark length recording method to sequential channel words formed by channel bits obtained by conversion according to a modulation method called FM.

[0005] To reproduce recorded information from a CD, light having a wavelength of 780 nm emitted from a semiconductor laser is irradiated with N light.
A is condensed on the signal surface as a light spot having a diameter of about 1.4 μm by an objective lens corresponding to 0.45, and reflected light from the light spot generated on the information signal surface, ie, Whether the spot of the light generated on the signal surface is at the position of the mark (pit),
The reflected light, which has a difference in the amount of light due to the diffraction phenomenon depending on whether it is in the position of A signal is reproduced, and a mark train (pit train) including the presence or absence of a mark (pit) is applied as an information track at a predetermined track pitch in the radial direction of the optical disc by applying the mark length recording method as described above. In the conventional general optical disk, information tracks are formed in the length direction of the mark, starting with the CD which is recorded and formed sequentially.

In the above-described optical disk, even when the recording density is increased and the amount of information recorded on the optical disk is increased, for example, the tilt of the optical disk, defocus, offset, increase in aberration of the optical system, etc. To ensure that the increase in jitter and error caused by various factors that degrade the optical reading performance falls within an acceptable range for the system, a data word based on the information to be recorded / reproduced, The minimum mark length (minimum bit length) formed on the optical disk by converting each to channel bits according to a predetermined modulation method
It is well known that the size of the optical disk is increased.
Then, an 8-bit data word (one symbol) based on information to be recorded / reproduced is converted into 14 bits according to a predetermined conversion table by using a well-known modulation method called so-called EFM as the modulation method. When converted into channel words of channel bits and the channel bit interval (cycle of the channel clock) is T, the pit length on the optical disk in the range from the shortest inversion interval (minimum inversion interval) 3T to the maximum inversion interval 11T. Alternatively, an information track is formed by pits or lands having a land length.

By the way, for example, image data is recorded even on a CD originally provided as an optical disk used for recording and reproducing acoustic information data.
In recent years, it has become desirable to increase the storage capacity of optical discs. However, as is well known, the spot diameter of light, which is closely related to the performance of reading recorded information from optical discs, And the numerical aperture NA of the reading lens (objective lens), and the spot diameter of the reading light (reproducing light) cannot be arbitrarily reduced. There is also a limit to the shortest pit length dimension formed on the optical disc, and it is therefore difficult to improve the recording density of the optical disc in a direction in which the shortest pit length dimension formed on the information signal surface of the optical disc is reduced.

As means for solving the above-mentioned problems, the presence or absence of a mark for giving a phase change to the light applied to the information track of the optical disc, and the width of the mark in the horizontal direction are reduced to a minute amount sufficiently smaller than the period of the information track. There has been proposed an optical recording method, a reproducing method, a recording / reproducing apparatus, and an optical disk for recording digital information on an optical disk by making the information carry both the displacement of the mark and the optical disk (for example, JP-A-4-74317). In the prior art described above,
Recording and reproduction of information by a mark sequence on an optical disc;
The mark or mark row is displaced in the horizontal direction of the mark row in accordance with the information to be recorded / reproduced, so as to increase the amount of information recorded on the optical disk. Also, in an optical disc conventionally used as a write-once CD, a guide groove for tracking control is formed to meander at a predetermined frequency, or the groove is further deformed by address information. ,further,
The guide groove as described above is not provided, and a signal for tracking control is recorded as a pit row meandering at a predetermined frequency, or only a part of the pit row is displaced in the track width direction to perform tracking. Recording of control signals has been performed.

The recorded information based on the presence / absence of a mark in the optical disks of various configurations as described above corresponds to the presence / absence of a mark obtained by irradiating a reproduction light spot focused by an objective lens onto the optical disk. The reproduction light of which the intensity is changed is reproduced as a reproduction signal from the photodetector, and the recording information due to the lateral displacement of the mark row is recorded in the radial direction of the recording medium of the reproduction light spot focused by the objective lens. A difference signal between two output signals obtained from the photodetector is reproduced as a reproduction signal in a state where the magnitude of the signal complementarily changes in accordance with the displacement of.

[0010]

By the way, as described above, there is an information track on which an information signal is recorded depending on the presence or absence of a mark, and the recording of the information signal is also performed by the displacement of the recording information in the radial direction of the recording medium. Of the reproduction light including the respective record information obtained by irradiating the reproduction optical spot focused by the objective lens on the optical disc being obtained, the reproduction light corresponding to the light intensity depending on the presence or absence of the mark is obtained from the photodetector. According to the first information signal and the displacement of the light spot for reproduction focused by the objective lens in the radial direction of the recording medium,
A second signal obtained as a difference signal between two output signals obtained from the photodetector in a state where the magnitude of the signal changes complementarily.
Of the two information signals, the signal level of the second information signal is lower than that of the first information signal. The first information in the second information signal may be caused by various causes such as, imbalance of the gain of the difference signal processing system, radial inclination of the optical disk surface, and aging of the servo system.
This causes a problem that the signal quality of the second information signal deteriorates due to the crosstalk of the information signal, and a measure for improving the problem is required.

[0011]

According to the present invention, there is provided an optical disk having an information track on which an information signal is recorded depending on the presence or absence of a mark, and recording the information signal by displacement of the recorded information in a radial direction of a recording medium. A reproduction light containing each of the above-mentioned recording information obtained by irradiating the objective recording medium with a reproduction light spot focused by an objective lens is provided to at least one photodetector, and an output from the photodetector is provided. Means for obtaining a first information signal corresponding to the light intensity based on the presence or absence of the mark based on the signal, and second information corresponding to the displacement of the recorded information in the radial direction of the recording medium based on the output signal from the photodetector A signal obtaining means for obtaining a signal from the objective lens so that the first information signal is not cross-talked in the second information signal. A recording / reproducing apparatus for an optical recording medium comprising means for displacing the optical recording medium in a radial direction from a reference position of the tracking control operation, and an optical recording medium for the optical recording medium. An inclination state detecting means for obtaining a signal indicating the amount of inclination in the radial direction of the board, and an output from the inclination state detecting means so that the first information signal does not crosstalk in the second information signal. Means for displacing the optical axis of the objective lens from the reference position of the tracking control operation in the radial direction of the optical recording medium based on the signal, and a recording / reproducing apparatus for the optical recording medium, and the optical axis of the objective lens Means for displacing the optical axis of the objective lens at a predetermined period in the radial direction of the optical recording medium, and Means for generating a signal indicating the state of the crosstalk of the first information signal into the second information signal based on the signal output from the means for obtaining the second information signal; and a signal indicating the state of the crosstalk. By
Means is provided for displacing the optical axis of the objective lens from the reference position of the tracking control operation in the radial direction of the optical recording medium so that the first information signal does not crosstalk in the second information signal. A recording / reproducing apparatus for an optical recording medium comprising: an information track on which an information signal is recorded depending on the presence or absence of a mark; and an optical signal on which an information signal is recorded by displacement of recording information in a radial direction of the recording medium. A reproduction light containing each of the above-mentioned recording information obtained by irradiating the objective recording medium with a reproduction light spot focused by an objective lens is provided to at least one photodetector, and an output from the photodetector is provided. Means for obtaining a first information signal corresponding to the light intensity based on the presence or absence of the mark based on the signal, and correspondence with the displacement of the recording information in the radial direction of the recording medium based on the output signal from the photodetector An optical recording medium recording / reproducing apparatus including means for obtaining a second information signal, and a tracking control system, wherein the first information signal is crosstalked in the second information signal. Means for displacing the optical axis of the objective lens from the reference position of the tracking control operation in the radial direction of the optical recording medium so that the optical axis of the objective lens is not optically recorded by the operation of the displacement means. Means for operating a tracking control system so that the tracking error becomes zero in a state of being displaced in the radial direction of the medium, and a recording / reproducing apparatus for an optical recording medium comprising: In the recording / reproducing apparatus, a tilt state detecting means for obtaining a signal indicating an amount of tilt in a radial direction on the board surface of the optical recording medium, and a state in which the first information signal is not cross-talked in the second information signal Means for displacing the optical axis of the objective lens from the reference position of the tracking control operation in the radial direction of the optical recording medium based on the output signal from the tilt state detecting means, A device for operating a tracking control system so that a tracking error becomes zero in a state where the optical recording medium is radially displaced by the operation of the displacement means, A means for displacing the optical axis of the objective lens in a radial direction of the optical recording medium at a predetermined cycle, and the optical axis of the objective lens being predetermined; In the state of being displaced periodically, the second
Based on the signal output from the means for obtaining the information signal of
Means for generating a signal indicating the state of crosstalk of the first information signal into the second information signal, and a signal indicating the state of crosstalk, the first information signal being included in the second information signal. Means for displacing the optical axis of the objective lens from the reference position of the tracking control operation in the radial direction of the optical recording medium so that the optical axis of the objective lens is not cross-talked. Means for operating a tracking control system so that a tracking error becomes zero in a state where the recording medium is displaced in a radial direction, and a recording / reproducing apparatus for an optical recording medium, and an information signal based on the presence or absence of a mark. The objective lens collects information on an optical recording medium having an information track on which information signals are recorded, and on which an information signal is also recorded by displacement of recording information in the radial direction of the recording medium. The reproduction light including the above respective recording information of a light spot obtained by irradiating the reproduction, at least 1
Means for obtaining a first information signal corresponding to the light intensity based on the presence or absence of a mark based on an output signal from the photodetector, and recording a reproduction light spot focused by an objective lens. Means for obtaining a second information signal by a difference signal between two output signals obtained from the photodetector in a state where the magnitude of the signal is complementarily changed in accordance with the radial displacement of the medium. A tilt state detecting means for obtaining a signal indicating a tilt amount of the optical recording medium in the radial direction on the board surface, and obtaining the second information signal. Is output in a state where the size is changed complementarily from the photodetector used for
Means for relatively changing the signal levels of the two output signals based on the output signal from the tilt state detecting means, and a recording / reproducing apparatus for an optical recording medium, and recording on the optical recording medium. In the reproducing apparatus, the signal levels of two output signals output in a state where the magnitudes are complementarily changed from the photodetector used to obtain the second information signal are predetermined. Means for changing at a cycle, and a signal output from means for obtaining the second information signal in a state where the signal levels of the two output signals from the photodetector are changed at a predetermined cycle. Means for generating a signal indicating the state of the crosstalk of the first information signal into the second information signal, and a size of the photodetector used to obtain the second information signal, Complementary Means for relatively changing the signal levels of the two output signals output in the state of being changed in accordance with the signal indicating the state of the crosstalk. I will provide a.

[0012]

The object track is recorded on an information track on which an information signal is recorded according to the presence or absence of a mark, and on an optical recording medium (optical disc) on which an information signal is also recorded by a displacement of recorded information in a radial direction of the recording medium. By irradiating a reproduction light spot focused by a lens, reproduction light including the above-described respective record information is generated from the optical disk, and is supplied to a photodetector. The first depending on the presence or absence of a mark on an optical disc
Is output from the photodetector as a reproduction signal corresponding to the light intensity of the reproduction light from the optical disk. In addition, when the reproduction light spot focused by the objective lens and the recording information of the recording medium are relatively displaced in the radial direction of the recording medium, the light detector detects that the size is complementary and changes. A signal component in a predetermined frequency region in a difference signal between the two output signals to be output is used as a second information signal, and a signal component in a frequency region lowest from the DC region in the difference signal is used as a tracking error signal as a tracking control system. Supplied to

Since the second information signal is obtained as a difference signal between the two output signals output from the photodetector as described above, the two information signals are used to obtain the difference signal. If the first information signal component included in the second information signal is the same, the first information signal does not cross-talk in the second information signal, but the position shift of the optical head, the position shift of the photodetector, the difference signal The first information signal crosstalks in the second information signal due to various causes such as imbalance of the gain of the processing system, radial inclination of the optical disk surface, and aging of the servo system. Since the amount of displacement of the recording information for generating the information signal on the recording medium is extremely small,
The signal level of the second information signal is extremely low, and the first information signal has the first level due to various causes as described above.
Crosstalk in the second information signal obtained as the difference signal, the S / N of the second information signal
Worsens.

In the recording / reproducing apparatus for an optical recording medium according to the present invention, the position of the light spot for reproduction (the position of the optical axis of the objective lens) is shifted from the center position of the track in the radial direction of the optical disk. The first in the second information signal
Or the position of the light spot for reproduction is shifted from the center position of the track in the radial direction of the optical disk, and
In a state where the first information signal component is not cross-talked in the information signal of
By generating a signal for canceling the tracking error signal generated in the tracking control system according to the deviation amount of the optical axis of the objective lens and supplying it to the tracking control system, the deviation amount of the optical axis of the objective lens is reduced. The tracking control is performed in a compensated state.

Further, the inclination of the optical disk in the radial direction is detected, and the position of the light spot for reproduction (the position of the optical axis of the objective lens) is determined from the center position of the track in the radial direction of the optical disk in accordance with the amount of inclination. In this case, the first information signal component is prevented from crosstalk in the second information signal, or the position of the spot of the light spot for reproduction is changed according to the radial inclination of the optical disk. The first information signal component is prevented from crosstalk in the second information signal by shifting the center information from the center position in the radial direction of the optical disk, and the tracking control system is adjusted in accordance with the optical axis shift amount of the objective lens. By generating a signal for canceling the tracking error signal generated in accordance with the deviation amount of the optical axis of the objective lens and supplying it to the tracking control system, Shift amount of the optical axis of the objective lens so that the tracking control is performed in a state of being compensated. Further, the optical axis of the objective lens is displaced at a predetermined cycle in the radial direction of the optical recording medium, and in the state where the optical axis of the objective lens is displaced at the predetermined cycle as described above, A signal indicating a state where the first information signal is crosstalking is generated in the second information signal, and the optical axis of the objective lens is optically recorded from the reference position of the tracking control operation by the signal indicating the state of crosstalk. By displacing in the radial direction of the medium, the first information signal is prevented from crosstalk in the second information signal.

Alternatively, when the reproducing light spot converged by the objective lens and the recording information on the recording medium are relatively displaced in the radial direction of the recording medium, the size is changed complementarily. The signal levels of two output signals output from the photodetector are relatively changed based on a signal obtained by detecting a radial inclination of the optical disc, and the first information signal is included in the second information signal. Information signal is not crosstalked. Alternatively, when the reproduction light spot focused by the objective lens and the recording information of the recording medium are relatively displaced in the radial direction of the recording medium, the size of the recording medium is changed in a complementary manner from the photodetector. The signal levels of the two output signals to be output are converted into a first information signal generated in a state where the optical axis of the objective lens is displaced at a predetermined cycle in the radial direction of the optical recording medium. Is relatively changed based on a signal indicating that the information signal is cross-talked, so that the first information signal is not cross-talked in the second information signal.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a recording / reproducing apparatus for an optical recording medium according to the present invention. 1 to 8 are block diagrams showing a schematic configuration of a recording / reproducing apparatus for an optical recording medium according to the present invention, and FIGS. 9 to 11 are waveform diagrams for explaining the operation. 1 to 8, D denotes an optical recording medium (optical disk). An optical disc D to be recorded / reproduced by the optical recording / reproducing apparatus of the present invention has an information track on which an information signal is recorded depending on the presence or absence of a mark, and an information signal due to a displacement of recorded information in a radial direction of a recording medium. Optical disk D on which recording is also performed, that is, for example, a guide groove for tracking control formed in a meandering state at a predetermined repetition cycle is provided in advance, or the shape of the guide groove is further changed by address information. A mark,
An optical disk for recording an information signal based on an array of non-marks, a guide groove for tracking control is not provided, and a signal for tracking control and other signals are formed by forming a pit row meandering at a predetermined repetition period. An optical disk having a configuration as shown by a recorded optical disk, an optical disk in which only a part of a pit row is displaced in the width direction of a track, and a signal for tracking control and other signals are recorded.

The optical disk D is rotated at a predetermined rotation speed by a drive motor 19 (not shown in FIG. 1) not shown. 1 is a light source (for example, a semiconductor laser), 2 is a collimating lens, 3 is a beam splitter,
4 is a reflecting mirror, 5 is an objective lens, 8 is an actuator of an automatic control system, 9 is a photodetector, 10 is a subtractor,
11 is a band-pass filter, 13 and 18 are adders, 15 is a low-pass filter, and 16 is a tracking control circuit. As the actuator 8 of the automatic control system, the objective lens 5 is displaced in the optical axis direction by the focus control signal in the automatic focus control circuit, or the objective lens 5 is displaced by the tracking control signal in the automatic tracking control circuit. A known configuration that is orthogonal to the optical axis of the optical disk and can be displaced in the radial direction of the optical disk can be selectively used. In addition,
In each drawing, illustration and description of a rotation control system, an automatic focus control circuit, and the like are omitted.

A line indicated by reference numeral 7 in the optical disk D in FIG. 1 is an example of an information track formed in a meandering state at a predetermined repetition period or a part of a guide groove for tracking control. Reference numeral 6 denotes a reproduction light spot (a reproduction light spot) generated on the optical disc D by being converged by the objective lens 5. The reproduction light radiated from the light source 1 is collimated by the collimator lens 2 and then enters the beam splitter 3 where the beam is split.
Is reflected by the reflecting mirror 4 and enters the objective lens 5. The reproduction light converged by the objective lens 5 causes a light spot 6 for reproduction on the optical disc D as described above. The reflected light from the spot 6 of the reproduction light of the optical disk D is detected by the two light detections constituting the photodetector 9 through the optical path of the objective lens 5 → reflector 4 → beam splitter 3 → photodetector 9. The parts PD1 and PD2 are irradiated. The hatched portion in the photodetector 9 in FIGS. 1 to 8 is the portion irradiated by the reflected light from the spot 6 of the reproduction light of the optical disk D described above.

The photodetector 9 described above is exemplified in FIG. 1 as using a two-segment photodetector composed of two photodetectors PD1 and PD2. As 9, a quadrant photodetector composed of four photodetectors may be used. The position of the principal ray of the reflected light from the optical disk D given to the photodetector 9 is the position of the optical disk D
If the position of the spot 6 of the reproduction light applied to the optical disk D is located on the center line of the information track, it is located on the boundary 9a between the two photodetectors PD1 and PD2 in the photodetector 9, and the optical disc D
When the position of the spot 6 of the reproduction light irradiated on the optical disc D is shifted from the center line of the information track in the radial direction of the optical disc D (the width direction of the information track), the position of the spot 6 from the optical disc D is changed according to the direction of the shift. The position of the principal ray of the reflected light is determined by the boundary 9a between the two photodetectors PD1 and PD2 in the photodetector 9.
From the line, it moves to one of the light detection unit PD1 and the light detection unit PD2.

Output signals from the two photodetectors PD1 and PD2 in the photodetector 9 are supplied to a subtractor 10 and an adder 13. The signal added by the adder 13 is sent to an output terminal 14. The output signal sent to the output terminal 14 is recorded on an information track of the optical disc D in a mark or non-mark arrangement. It is a first information signal generated corresponding to the light intensity due to information. The subtractor 10 outputs a difference signal between the two output signals from the two photodetectors PD1 and PD2 in the photodetector 9. However, the polarity and magnitude of the difference signal output from the subtractor 10 are different. Is zero in the state where the center of the spot of the reproduction light is located at the center position of the mark of the optical disc D or the center position of the guide groove, but the center position of the mark of the optical disc D or the center position of the guide groove In the case where the center position of the spot of the reproduction light is deviated, the polarity and magnitude of the difference signal output from the subtracter 10 are changed corresponding to the direction and magnitude of the deviation. Become.

The output signal from the subtractor 10 is supplied to a band-pass filter 11 and a low-pass filter 15. The signal of the frequency component that has passed through the band-pass filter 11 is sent to the output terminal 14 as a second information signal corresponding to the displacement of the recording information in the radial direction of the optical disk. The signal composed of the DC component and the low frequency component that has passed through the adder 15 is a tracking error signal, and the tracking error signal is supplied to the tracking control circuit 16 via the adder 18. The tracking control signal generated by the tracking control circuit 16 is supplied to the actuator 8 of the automatic control system. Further, an offset signal (offset voltage) generated by various means described later is supplied to the adder 18 via an input terminal 17.

The offset signal supplied via the input terminal 17 is superimposed on the tracking error signal by the adder 18, so that the reference position for tracking control can be set according to the polarity and magnitude of the offset signal. It will be shifted in the radial direction of the optical disk. That is, when the signal output from the adder 18 is supplied, the tracking control signal output from the tracking control circuit 16 that generates the tracking control signal is supplied to the actuator 8 of the automatic control system. The actuator 8 of the automatic control system moves the optical axis of the objective lens 5 from the reference position in the tracking control operation in the radial direction of the optical disc in accordance with the polarity and magnitude of the offset signal supplied to the input terminal 17. To displace in the direction and distance determined respectively.

When the polarity and the magnitude of the offset signal supplied to the input terminal 17 are appropriately set, the first information to the second information signal is generated due to various causes as described above.
It is also possible to make the cross-talk of the information signal of the above to zero.
This point will be specifically described with reference to FIGS. 9 and 10 as follows. 9 (a) and 10 (a) show information tracks 7 on the optical disc D by an arrangement of marks and non-marks (for simplicity of illustration, they are shown as information tracks by a pit train of a single frequency). ) Schematically shows a state in which the optical disk is displaced in the radial direction of the optical disk at a specific cycle, and the tracking state of the information track 7 by the reproducing light spot 6 for reading the information signal from the information track 7 is shown. FIG. 9A shows an example in which the center of the information spot 7 on the optical disc D is arranged in the arrangement of marks and non-marks, and the center of the reproduction light spot 6 is located at the center. FIG. 11 is a diagram exemplifying a state in which the light spot 6 for reproduction tracks the information track 7, and FIG. 10A shows an information record by arrangement of marks and non-marks on the optical disc D. From the center of the click 7, in a state where the center of the light spot 6 for reproduction is shifted, the light spot 6 is the information track 7 for reproduction
It is a figure which illustrates the state which is tracking.

9 (b) and 10 (b)
The output signal from one photodetector PD1 of the photodetector 9, FIGS. 9C and 10C show the output signal from the other photodetector PD2 of the photodetector 9. , FIG. 9 (d)
FIG. 10D shows a subtractor 10 to which output signals from two photodetectors PD1 and PD2 in the photodetector 9 are given.
FIG. 9E shows the bandpass filter 1 to which the output signal from the subtracter 10 is supplied.
1 shows an output signal. Then, FIG.
(B) and (c) and (b) and (c) of FIG. 10 show two photodetectors PD in the photodetector 9 respectively.
1 and the output signal from PD2 are the reflected light amounts at the mark (pit) and non-mark (land) portions in the information tracks of the optical disc D shown in FIGS. 9 (a) and 10 (a). And the corresponding voltage value.

Now, in the optical recording / reproducing apparatus, the displacement of the optical head, the displacement of the photodetector, the imbalance of the gain of the difference signal processing system, the inclination of the optical disk surface in the radial direction, the temporal change of the servo system, etc. In the absence state, as shown in FIG. 9A, the center of the reproduction light spot 6 is located at the center position of the information track 7 according to the arrangement of the marks and non-marks on the optical disk D. If you are tracking an information truck while you are located,
The two light detectors PD1, PD2 of the light detector 9 to which the reflected light from the reproduction light spot 6 focused by the objective lens 5 is given.
An output signal from the subtracter 10 to which the two output signals output from the PD2 are supplied, that is, the above-described photodetector 9
Out of the first information signals generated corresponding to the arrangement of the marks and non-marks on the optical disc D included in the difference signal between the two output signals output from the two photodetectors PD1 and PD2. Since the frequency component existing in the frequency band of the second information signal (the pass frequency band of the band-pass filter 11) becomes extremely small, the information track based on the arrangement of marks and non-marks on the optical disc D is obtained. 7, the band-pass filter 1 corresponding to the displacement information in the radial direction.
The second information signal output from 1 to the output terminal 12 shows a good S / N as illustrated in FIG. 9 (e).

Next, in the optical recording / reproducing apparatus, the displacement of the optical head, the displacement of the photodetector, the imbalance of the gain of the difference signal processing system, the inclination of the optical disk surface in the radial direction, the temporal change of the servo system, etc. In the case where there is an error, even if the tracking control system in the recording / reproducing apparatus is operating normally, the spot of the reproducing light is marked or unmarked on the optical disc D as illustrated in FIG. In this case, the information track is tracked in a state equivalent to a state in which the information track is tracked in a state shifted from the center position of the information track 7 by the arrangement of the information tracks 7. In accordance with the relative displacement of the light spot 6 and the position of the recording information in the radial direction of the recording medium, the magnitude of the signal complementarily changes, and the two photodetectors PD1, P2 of the photodetector 9 are changed. The two output signals output from D2 are as illustrated in FIGS. 10B and 10C, respectively.

Thus, the two photodetectors PD1, PD1 of the photodetector 9
The output signal from the subtracter 10 to which the two output signals shown in (b) and (c) of FIG. 10 output from the PD2 are supplied, as illustrated in (d) of FIG. A large pulsating current that is asymmetrical with respect to the AC axis is generated, and the first information signal generated corresponding to the arrangement of marks and non-marks on the optical disc D includes the frequency band of the second information signal (band-pass filter 11). The frequency component existing within the band pass filter) becomes large, and the band pass filter corresponds to displacement information of the information track 7 in the radial direction due to the arrangement of marks and non-marks on the optical disc D. The second information signal output from the output terminal 11 to the output terminal 12 has a poor S / N with large amplitude and phase fluctuations due to the crosstalk of the first information signal in the second information signal.

According to the present invention, as described above, in the optical recording / reproducing apparatus, the displacement of the optical head, the displacement of the photodetector, the imbalance of the gain of the difference signal processing system, the inclination of the optical disk surface in the radial direction, the servo When there is a time-dependent change in the system or the like, two output signals output from the two photodetectors PD1 and PD2 of the photodetector 9 are converted into a difference signal by a subtractor 10, and then a band-pass filter 11 is used. And a signal generated corresponding to the amount of reflected light in each of the mark (pit) and the non-mark (land) in the information track of the optical disc D is subtracted from the signal output from the band-pass filter 11. In order to prevent the first information signal from being cross-talked in the second information signal without deteriorating the S / N of the second information signal without being removed even by the subtraction operation in the device 10, The offset signal is supplied via an input terminal 17 so that the offset signal is superimposed on the tracking control signal by an adder 18 and supplied to an actuator 8 of an automatic control system. The optical axis of No. 5 is displaced from the reference position in the tracking control operation in a direction and a distance respectively determined in the radial direction of the optical disk, and the crosstalk of the first information signal to the second information signal is set to zero. .

In the recording / reproducing apparatus for the optical recording medium shown in FIG. 1, when the offset signal is not supplied to the input terminal 17, the reproduction light emitted from the light source 1 is focused by the objective lens 5 as described above. The reflected light from the reproduced light spot 6 on the optical disk D is transmitted to the objective lens 5 →
The two light detectors P constituting the light detector 9 are formed by the optical path of the reflecting mirror 4 → the beam splitter 3 → the light detector 9.
D1 and PD2, and the two photodetectors PD
1. After the output signal from PD2 is subtracted by the subtractor 10, a low-pass filter 15 → adder 18 → tracking control circuit 16 → automatic control system actuator 8 → objective lens 5. By the operation of the tracking control loop, the position control of the spot 6 of the reproduction light on the optical disc D in the width direction of the information track is performed with the position where the error signal in the above-mentioned one round of the tracking control system becomes zero as a reference position. However, all of the functions of the components of the tracking control system, the components of the optical head, etc. constituting the recording / reproducing apparatus for the optical recording medium described above, and the mounting positions of the components are all appropriate. In such a case, the reference position of the reproduction light spot 6 is the center position in the width direction of the information track, and For the first information signal component contained in the two output signals from the two light detector PD1 constituting the light detector 9, PD2 becomes the same size,
No crosstalk of the first information signal to the second information signal occurs.

However, among the functions and mounting positions of the components of the tracking control system and the components of the optical head constituting the recording / reproducing apparatus for the optical recording medium shown in FIG. In the case where one or more objects are in an inappropriate state, the tracking control operation by the tracking control system allows the center of the spot 6 of the reproduction light to correctly follow the center of the information track in the width direction. Since the magnitudes of the first information signal components included in the two output signals from the two photodetectors PD1 and PD2 constituting the photodetector 9 are different from each other, the second In some cases, the first information signal crosstalks in the information signal. Accordingly, in the recording / reproducing apparatus for an optical recording medium shown in FIG. 1, an offset signal having a predetermined polarity and magnitude is supplied from an input terminal 17 to an adder 18, and an optical signal for reproduction is supplied by the offset signal. The position of the spot 6 (the position of the optical axis of the objective lens 5) is shifted by a predetermined amount in a predetermined direction in the radial direction of the optical disk, so that only the second information signal is output to the output terminal 12.

In the recording / reproducing apparatus for the optical recording medium shown in FIG.
The polarity and magnitude of the offset signal to be supplied to the output terminal 12 are determined so that only the second information signal can be output to the output signal from the output terminal 12. An offset signal having a polarity and a magnitude such that only the second information signal is output from the output terminal is output from the output terminal 12.
While observing the waveform of the output signal from the oscilloscope, it can be easily determined by changing the magnitude of the polarity of the DC voltage applied to the input terminal 17, and the offset having the polarity and magnitude determined as described above. A DC voltage used as a signal may be set in the device and supplied to the input terminal 17. If the above-described setting operation of the offset signal supplied to the input terminal 17 is performed in an adjustment step at the time of manufacturing the optical recording medium recording / reproducing apparatus, the defect of the optical recording medium recording / reproducing apparatus due to a manufacturing error can be obtained. The rate can be greatly improved.

Next, the recording / reproducing apparatus for an optical recording medium of the present invention shown in FIG. 2 is the adder 18 in the recording / reproducing apparatus for an optical recording medium of the present invention described above with reference to FIG.
This is an embodiment of a configuration in which an offset signal generated based on an output signal from the tilt sensor 20 is used as an offset signal supplied to the input terminal 17 through the input terminal 17. The recording / reproducing apparatus for an optical recording medium according to the present invention includes the adder 1 in the recording / reproducing apparatus for an optical recording medium according to the present invention described above with reference to FIG.
This is an embodiment of a configuration in which an offset signal generated based on an output signal from an oscillator 22 is used as an offset signal supplied to an input terminal 8 via an input terminal 17.

In the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIG. 2, the tilt sensor 20 for generating an offset signal is provided on the portion of the optical disk D where the objective lens 5 is irradiated with the reproducing light spot 6. A component configured to generate a tilt information signal of the optical disc corresponding to the radial tilt of the optical disc on the surface, and a component configured to generate an offset signal based on the tilt information signal of the optical disc described above are used. it can. The component for generating the tilt information signal of the optical disc in the tilt sensor 20 is, for example, a part for obtaining the tilt information on the optical disc D by converting the light emitted from the light emitting element into parallel light by the first collimator lens. On the other hand, the light is made incident along the radial direction of the optical disk D, and the light reflected by the optical disk
And focused on a two-divided photodetector arranged such that the light receiving surface is located on the focal plane of the second collimator lens, and
A known configuration that can generate a signal indicating tilt information in the radial direction of the optical disk based on two output signals output from the divided photodetectors can be used.

The component for generating the offset signal by supplying the signal indicating the tilt information in the radial direction of the optical disc D output from the component for generating the tilt information signal of the optical disc is provided by the optical disc D. Generates an offset signal having a polarity and a magnitude determined in correspondence with the signal indicating the tilt information in the radial direction, and supplies the offset signal to the adder 18. The adder 18 adds the signal from the low-pass filter 15. The offset signal is superimposed on the tracking error signal supplied to the optical device 18, and the position of the light spot 6 for reproduction (the position of the optical axis of the objective lens 5) in the radial direction of the optical disk is determined by the offset signal. The output terminal 12 is shifted by a predetermined amount in a predetermined direction so that only the second information signal can be output. .

The recording / reproducing apparatus for an optical recording medium of the present invention shown in FIG. 2 has an input terminal 17 connected to the adder 18 in the recording / reproducing apparatus for an optical recording medium of the present invention described above with reference to FIG. By using an offset signal generated based on an output signal from the tilt sensor 20 as an offset signal supplied through the optical disc D,
Is distorted in the second information signal due to the fact that the shape of the reproduction light applied to the two photodetectors PD1 and PD2 in the photodetector 9 is distorted due to the fact that the surface is inclined in the radial direction. It is possible to properly prevent the S / N of the second information signal output from the output terminal 12 from deteriorating due to the crosstalk of one information signal.

Next, the recording / reproducing apparatus for an optical recording medium of the present invention shown in FIG.
And an AC signal having a predetermined cycle as shown in FIG. 1 is supplied to the actuator 8 of the automatic control system so that the optical axis of the objective lens 5 is periodically displaced in the radial direction of the optical disk. And the position of the principal ray of the reflected light from the optical disc D given to the photodetector 9 is
The light detector 9 reciprocates between the two light detectors PD1 and PD2. The subtracter 10 to which the output signals of the two light detectors PD1 and PD2 in the light detector 9 are supplied. A signal indicating a state of crosstalk of the first information signal into the second information signal is generated from the output difference signal, and has an appropriate polarity and magnitude automatically generated based on the signal. This is a configuration mode in which an automatic control system for minimizing the first information signal crosstalked in the second information signal due to various causes by using an offset signal is provided (see FIG. The recording / reproducing apparatus for an optical recording medium shown in FIG.
Also, a substantially similar configuration is adopted in a recording / reproducing apparatus for an optical recording medium shown in FIG. 8 described later).

That is, in the optical recording medium recording / reproducing apparatus shown in FIG. 3, the output signal from the subtracter 10 is low as in the optical recording medium recording / reproducing apparatus described with reference to FIGS. Band-pass filter 15 and band-pass filter 1
1 and is also supplied to the detection circuit 26. As described above, an AC signal having a predetermined period oscillated by the oscillator 22 is supplied to the actuator 8 of the automatic control system. When the optical axis of the objective lens 5 is periodically displaced in the direction of the track width of the information track, the spot 6 of the reproduction light reciprocates in the width direction of the information track at the cycle of the AC signal.

If the position of the center of the spot 6 of the reproduction light is in a state where the first information signal is not cross-talked in the second information signal when the AC signal is zero, When an AC signal having a predetermined cycle from the oscillator 22 is supplied to the actuator 8 of the automatic control system, the reproduced light reciprocates in the width direction of the information track at the cycle of the AC signal and the optical disc D A photodetector 9 to which the reflected light from the upper reproduction light spot 6 is given.
The output signal of the subtractor 10 to which the two output signals from the two photodetectors PD1 and PD2 are supplied is as shown in FIG. 11B, and the AC signal is In the zero state, if the position of the center of the spot 6 of the reproduction light is in a state in which the first information signal is cross-talked in the second information signal, the predetermined position from the oscillator 22 is determined. The AC signal having the given period is supplied to the actuator 8 of the automatic control system, so that the spot 6 of the reproduction light reciprocates in the width direction of the information track at the period of the AC signal, and The output signal of the subtractor 10 to which the two output signals from the two photodetectors PD1 and PD2 in the photodetector 9 to which the reflected light from the spot 6 is given is exemplified in FIG. 11D. It becomes something like.

When the position of the spot 6 of the reproduction light on the optical disk D is at a position where the first information signal is not cross-talked in the second information signal, the output from the subtractor 10 shown in FIG. After the signal as exemplified in (b) is detected by the detection circuit 26, the low-pass filter 27
As shown in FIG. 11 (c), the low-frequency signal component extracted through is a signal having a frequency which is twice the frequency of the AC signal shown in FIG. 11 (a). In addition, when the position of the spot 6 of the reproduction light on the optical disc D is at a position that causes the first information signal to crosstalk in the second information signal, the output from the subtracter 10 shown in FIG. After the signal as exemplified in (d) is detected by the detection circuit 26, the low-frequency signal component extracted through the low-pass filter 27 is as shown in (e) of FIG. In addition, a signal having the same frequency as the frequency of the AC signal shown in FIG. 11A is obtained, and the phase of the minimum point of the envelope is shifted from the zero point of the AC signal shown in FIG. Shift.

Therefore, in the recording / reproducing apparatus for an optical recording medium shown in FIG. 3, the AC signal of a predetermined cycle oscillated by the oscillator 22 as described above is supplied to the actuator 8 of the automatic control system. The optical axis of the objective lens 5 is periodically displaced in the direction of the track width of the information track, and the position of the spot 6 of the reproduction light is reciprocated in the width direction of the information track at the cycle of the AC signal. Objective lens that can prevent the first information signal from being cross-talked in the second information signal based on the signal component obtained through the low-pass filter 27 after detecting the signal output from the detection circuit by the detection circuit 26 The offset voltage for setting the position of the optical axis of the objective lens 5 at the position of the optical axis of 5 (the position of the center of the spot 6 of the reproduction light) is generated by the offset voltage supply circuit 31, and the adder 1 It is as to give in.

That is, in the recording / reproducing apparatus for the optical recording medium shown in FIG. 3, the signal output from the low-pass filter 27 described above is exemplified by (c) of FIG. 11 or (e) of FIG. The signal 乗 算 is supplied to the multiplier 28, and the multiplier 28 multiplies the AC signal output from the oscillator 22 by the multiplier 28, and outputs the output signal from the multiplier 28 to the low-pass filter 2.
9 through the low-pass filter 29, the position of the optical axis of the objective lens 5 (the spot 6 of the reproduction light 6) is set so that the first information signal is not cross-talked into the second information signal. For generating an offset voltage for setting an offset voltage for setting a predetermined polarity and magnitude from the offset voltage supply circuit 31. The offset voltage having the output is output and supplied to the adder 18. Therefore, in the recording / reproducing apparatus for an optical recording medium shown in FIG. (The recording / reproducing apparatus for the optical recording medium shown in FIGS. 6 and 8) by automatically setting the position of the optical axis (the position of the center of the spot 6 of the reproducing light). Is the same).

With reference to FIGS. 1 to 3, the recording / reproducing apparatus for an optical recording medium according to the present invention described so far has the following features.
Due to the tracking control operation of the tracking control system, even if the center of the spot 6 of the reproduction light correctly traces the center portion in the width direction of the information track, the first information is included in the second information signal due to the various causes described above. In order to solve the problem that the information signal is cross-talked and the S / N is reduced, an offset signal having a predetermined polarity and magnitude is supplied to the input terminal 1.
7 to an adder 18 to shift the position of the light spot 6 for reproduction (the position of the optical axis of the objective lens 5) by a predetermined amount in the radial direction of the optical disk by a predetermined amount by the above-mentioned offset signal. Since only the second information signal is output to the information track 12, a position shifted from the center in the width direction of the information track (for example, a position shift amount of 0.1 μm or less when the track pitch is 1.6 μm) But,
A problem arises in that the tracking control operation for the spot 6 (position of the optical axis of the objective lens 5) of the reproduction light is performed as the reference position of the tracking control during the reproduction operation.

The recording / reproducing of the optical recording medium of the present invention having the configuration in which the above-mentioned problem does not occur in the optical recording medium recording / reproducing apparatus of the present invention described with reference to FIGS. The recording / reproducing apparatus for an optical recording medium of the present invention shown in FIGS.
In the recording / reproducing apparatus for an optical recording medium according to the present invention described above, the subtracter 25
And the adder 18 is provided between the tracking control circuit 16 and the actuator 8 of the automatic control system.
And supplies the subtractor 25 with the position signal of the optical axis of the objective lens generated by the control circuit 24 based on the position information of the objective lens detected by the lens position sensor 23. Therefore, in the recording / reproducing apparatus for the optical recording medium of the present invention shown in FIGS. 4 to 6, the offset signal is used in the same manner as in the recording / reproducing apparatus for the optical recording medium of the present invention described with reference to FIGS. In the state where the first information signal is not cross-talked in the second information signal by the supply of the second information signal, the position of the optical axis of the objective lens 5 (the position of the center of the spot 6 of the reproduction light) is displaced. The operation of the tracking control system for the spot 6 is performed in such a state that the center of the spot 6 of the reproduction light correctly traces the center in the width direction of the information track.

In the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIGS. 4 to 6, the lens position sensor 23 comprises:
The objective lens 5 detects the amount of displacement of the optical axis of the objective lens 5 from the position of the optical axis at the home position, and sends an output signal corresponding to the amount of displacement. As the lens position sensor 23, an appropriate one can be selected from many types of well-known position sensors, and for example, an optical position sensor may be used. An output signal from the lens position sensor 23 is
The control signal is converted into a control signal by the control circuit 24 and supplied to a subtracter 25 provided in a tracking control system. The control signal generated by the control circuit 24 is shown in FIG.
In the recording / reproducing apparatus for an optical recording medium of the present invention described above with reference to FIG. 3 to FIG. 3, the position of the optical axis of the objective lens 5 (the The offset of the tracking error signal generated in the tracking control system can be canceled in accordance with the amount of displacement of the optical axis of the objective lens 5 caused by the displacement of the center of the spot 6 of the reproduction light by the offset signal. This signal is supplied to the subtractor 25 described above, so that the tracking error signal output from the low-pass filter 15 described above with reference to FIGS. By performing the compensation, the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIGS. Is being Nau way.

In the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIG. 4, as in the recording / reproducing apparatus for an optical recording medium described with reference to FIG. An offset signal having a predetermined polarity and magnitude is supplied to the optical recording medium. The recording / reproducing apparatus for an optical recording medium of the present invention shown in FIG. 5 is the same as the recording / reproducing apparatus for an optical recording medium described with reference to FIG. And the tilt sensor 20
Since the offset signal having a predetermined polarity and magnitude is supplied to the adder 18 in the optical recording medium recording / reproducing apparatus shown in FIGS. The control signal generated by the control circuit 24 based on the output signal from the position sensor 23,
In the state where the first information signal is not cross-talked in the information signal of
A subtractor 25 supplies a control signal to the subtracter 25 so that the offset signal for displacing the position of the optical axis of the objective lens 5 (the position of the center of the spot 6 of the reproduction light) can cancel the influence on the operation of the tracking control system. In the state where the first information signal is supplied and compensates for the tracking error signal, and the tracking control system is performing the control operation according to the original tracking control characteristic, the second information signal in which the first information signal is not cross-talked is output. 12 can be output.

In the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIG. 6, similarly to the recording / reproducing apparatus for an optical recording medium described with reference to FIG. A periodic AC signal is supplied to an actuator 8 of an automatic control system, and the optical axis of the objective lens 5 is periodically displaced in the direction of the track width of the information track, so that the position of the spot 6 of the reproduction light is changed to the AC. The signal is reciprocated in the width direction of the information track at the cycle of the signal, and the signal output from the subtracter 10 is detected by the detection circuit 26, and then the low-pass filter 2
Based on the signal component obtained through 7, the position of the optical axis of the objective lens 5 (the position of the center of the spot 6 of the reproduction light) at which the first information signal can be prevented from crosstalking in the second information signal, Since the offset voltage for setting the position of the optical axis of the objective lens 5 is generated by the offset voltage supply circuit 31 and given to the adder 18, the offset voltage of the optical recording medium of the present invention shown in FIG. Even with recording and playback devices,
As described above, the control signal generated by the control circuit 24 based on the output signal from the lens position sensor 23, that is,
An offset signal for displacing the position of the optical axis of the objective lens 5 (the position of the center of the spot 6 of the reproduction light) in a state where the first information signal is not crosstalked in the second information signal is used for the operation of the tracking control system. A control signal capable of canceling the influence is supplied to the subtractor 25 to compensate the tracking error signal, and in a state where the tracking control system performs a control operation according to the original tracking control characteristic, the first A second information signal with no information signal crosstalk can be output from the output terminal 12.

In the recording / reproducing apparatus for the optical recording medium described above with reference to FIGS. 1 to 6, the objective lens 5 is kept in a state where the first information signal is not cross-talked in the second information signal. Although the position of the optical axis (the position of the center of the spot 6 of the reproduction light) is displaced, the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIGS. In order to prevent the first information signal from crosstalking in the signal, instead of displacing the position of the optical axis of the objective lens 5 (the position of the center of the spot 6 of the reproduction light), the objective lens 5 is used. When the focused reproduction light spot 6 and the recording information of the optical disc are relatively displaced in the radial direction of the optical disc, the light is output from the photodetector 9 in a state in which the size is complementarily changed. Change the signal level of two output signals relatively Configuration is used to cause.

In the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIGS. 7 and 8, the reproducing light radiated from the light source 1 is focused by the objective lens 5 to form a reproducing light spot 6 Is generated. Then, the above-mentioned reflected light from the spot 6 of the reproduction light is converted from the objective lens 5 to the reflecting mirror 4.
→ Beam splitter 3 → Two optical detectors PD1, P2 constituting the optical detector 9 by the optical path of the optical detector 9.
D2. The two photodetectors PD1, PD2
Is supplied to the adder 13 and the subtractor 10, and the output signal from the photodetector PD1 is supplied to the variable resistor 32, and the output signal from the photodetector P1 is supplied to the variable resistor 32.
The output signal from D2 is provided to resistor 33.

In the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIGS. 7 and 8, the two light beams constituting the objective lens 5, the reflecting mirror 4, the beam splitter 3, and the photodetector 9. A circuit consisting of detection units PD1, PD2, a subtractor 10, a low-pass filter 15, a tracking control circuit 16, an actuator 8 of an automatic control system, an objective lens 5,... Constitutes a single circuit of a tracking control loop. The position control of the spot 6 of the reproduction light on the optical disc D is performed in the width direction of the information track, with the position where the error signal in the above-described one-track tracking control system becomes zero being a reference position. When the components of the tracking control system, the components of the optical head, and the like constituting the recording / reproducing apparatus for the optical recording medium, the functions of the respective components and the mounting positions of the components are all appropriate. Does not cause crosstalk of the first information signal to the second information signal, but causes crosstalk of the first information signal in the second information signal if the above conditions are not satisfied. Is as described above.

In the recording / reproducing apparatus for the optical recording medium shown in FIGS. 7 and 8, the components of the tracking control system and the components of the optical head which constitute the recording / reproducing apparatus for the optical recording medium, etc. If any one or more of the functions and mounting positions of the optical disc becomes inappropriate, the tracking control operation by the tracking control system causes the center of the spot 6 of the reproduction light to have the width of the information track. The magnitude of the first information signal component included in the two output signals from the two photodetectors PD1 and PD2 constituting the photodetector 9 even if the central portion in the direction is correctly traced. Are different, the first information signal crosstalks in the second information signal.

Therefore, in the recording / reproducing apparatus for the optical recording medium shown in FIGS. 7 and 8, the two output signals from the two photodetectors PD1 and PD2 in the photodetector 9 are included in the photodetector 9 due to the above-mentioned reasons. Even when the magnitude of the first information signal component included is different, the two photodetectors PD1, PD2,
The size of the first information signal component contained in the two output signals from the two photodetectors PD1 and PD2 is made equal by the circuit arrangement provided in the output circuit of PD2. After that, the signal is supplied to the subtractor 34, and the output signal of the subtractor 34 is taken out through the band-pass filter 11, whereby the second information signal in a state where the first information signal is not cross-talked is obtained from the output terminal 12. It is made to be able to be done.

In the recording / reproducing apparatus for the optical recording medium shown in FIGS. 7 and 8, two photodetectors PD in the photodetector 9 are used.
1. A circuit arrangement provided in the output circuits of the two photodetectors PD1 and PD2 so that the first information signal components contained in the two output signals from PD2 have the same magnitude. Although the variable resistor 32 and the resistor 33 are shown as being used, this is an example of a circuit for facilitating the understanding of the configuration principle and the operation principle. For example, a variable gain control circuit, a variable attenuation network, or the like is used, and the first information included in two output signals from the two photodetectors PD1 and PD2 in the photodetector 9 described above. After the signal levels of the signal components are made equal, the signal components are supplied to the subtractor 34.

In the recording / reproducing apparatus for the optical recording medium shown in FIGS. 7 and 8, the first information contained in the two output signals from the two photodetectors PD1 and PD2 in the photodetector 9 is shown. With the signal components having the same magnitude, the photodetector 9
The resistance value of the variable resistor 32 is changed by the control signal supplied to the input terminal 35 so that the two output signals from the two photodetectors PD1 and PD2 are supplied to the subtractor 34. The control signal applied to the input terminal 35 is changed while observing the waveform of the output signal from the output terminal 12 with an oscilloscope so that the output signal from the terminal 12 becomes only the second information signal.

In the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIG. 7, the control signal supplied to the variable resistor 32 via the input terminal 35 is based on the output signal from the tilt sensor 20. FIG. 8 shows an embodiment of the configuration in which the control signal generated by the control circuit 31 is used. In the recording / reproducing apparatus for an optical recording medium of the present invention shown in FIG. To the oscillator 2 as a control signal supplied to the
This is an embodiment of the configuration in which the control signal generated by the control signal generation circuit 36 based on the output signal from the control signal 2 is used.

In the recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIG. A device having a component for generating a tilt information signal of the optical disc corresponding to the radial tilt of the optical disc on the surface can be used. For example, the light emitted from the light emitting element is made parallel by the first collimator lens Then, the light is incident on a portion of the optical disk D where tilt information is to be obtained along the radial direction of the optical disk D, and the light reflected by the optical disk surface is focused by a second collimator lens. , Into a two-divided photodetector arranged such that the light receiving surface is located on the focal plane of the second collimator lens, Based on the two output signals outputted from the two-division photodetector noted, it may be used those known configuration a signal indicating the inclination information in the radial direction of the optical disc can be generated.

The control signal generating circuit 36 supplied with the signal indicating the tilt information in the radial direction of the optical disc D output from the tilt sensor 20 corresponds to the signal indicating the tilt information in the radial direction of the optical disc D. A control signal having a predetermined magnitude is generated and supplied to the variable resistor 32. The variable resistor 32 detects light when the magnitudes of the first information signal components included in the two output signals from the two photodetectors PD1 and PD2 in the photodetector 9 are the same. The resistance value is changed by the control signal so that the two output signals from the two photodetectors PD1 and PD2 in the detector 9 are supplied to the subtractor 34. Therefore, the signal output from the subtractor 34 to the output terminal 12 via the band-pass filter 11 is only the second information signal in which the first information signal is not cross-talked.

The recording / reproducing apparatus for an optical recording medium according to the present invention shown in FIG. 7 performs control based on an output signal from the tilt sensor 20 as a control signal supplied to the variable resistor 32 via an input terminal 35. By using the control signal generated by the signal generation circuit 36, the light is irradiated on the two light detection units PD1 and PD2 in the light detector 9 because the surface of the optical disk D is inclined in the radial direction. Distortion in the shape of the reproduction light prevents the first information signal from crosstalking in the second information signal, thereby favorably preventing the S / N of the second information signal output from the output terminal 12 from deteriorating. it can.

Next, the recording / reproducing apparatus for an optical recording medium of the present invention shown in FIG.
In the state where the AC signal of a predetermined cycle as shown in the example is generated and the resistance value of the variable resistor 32 is periodically changed by a control signal generated based on the AC signal, Two photodetectors PD in photodetector 9
1, a signal indicating the state of crosstalk of the first information signal into the second information signal is generated from the difference signal output from the subtractor 34 to which the output signal of PD2 is supplied, and based on the signal, An output side of the subtractor 34 so that the first information signal crosstalked into the second information signal by various causes is minimized by using the automatically generated control signal,
The variable resistor 32 connected to the input side of the subtractor 34
, A detection circuit 26, a low-pass filter 27, a multiplier 28, a low-pass filter 29, an oscillator 22,
A circuit arrangement configured using a control signal generation circuit 36 and the like is provided. That is, in the optical recording medium recording / reproducing apparatus shown in FIG. 8, the output signal from the subtractor 34 is sent to the output terminal 12 via the band-pass filter 11 and is also supplied to the detection circuit 26. ing. The AC signal of a predetermined cycle oscillated by the oscillator 22 is supplied to the control signal generation circuit 36, and the control signal generated by the control signal generation circuit 36 is supplied to the variable resistor 32, thereby making the above-described operation. The resistance value of the variable resistor 32 changes with the cycle of the AC signal.

When the AC signal is zero, the difference signal output from the subtractor 34 to which the output signals of the two photodetectors PD1 and PD2 in the photodetector 9 are supplied is the second information signal. When the first information signal does not crosstalk into the AC signal, an AC signal having a predetermined cycle from the oscillator 22 is supplied to the control signal generation circuit 36, and the The output signal of the subtracter 34 to which the two output signals from the two photodetectors PD1 and PD2 in the detector 9 are supplied is as exemplified in FIG. When the AC signal is zero, the two photodetectors PD1 and PD2 in the photodetector 9
If the difference signal output from the subtractor 34 to which the output signal is supplied is in such a state that the first information signal is crosstalked into the second information signal, the oscillator 2
2 is supplied to the control signal generating circuit 36, so that two output signals from the two photodetectors PD1 and PD2 in the photodetector 9 are subtracted. The output signal of the device 34 is as illustrated in FIG.

The two photodetectors PD in the photodetector 9
1, when the difference signal output from the subtractor 34 to which the output signal of PD2 is supplied is located at a position where the first information signal is not cross-talked in the second information signal, The low-frequency signal component extracted from the low-pass filter 27 after the signal illustrated in (b) of FIG. 11 output from the low-pass filter 34 is detected by the detection circuit 26 is represented by (c) in FIG. ), The signal has a frequency twice as high as the frequency of the AC signal shown in FIG. 11A, and the two photodetectors PD in the photodetector 9.
1, when the difference signal output from the subtractor 34 to which the output signal of PD2 is supplied is located at a position where the first information signal is crosstalked in the second information signal, 3
The low-pass signal component extracted from the low-pass filter 27 after the signal illustrated in FIG. As shown in FIG. 11, the frequency of the AC signal shown in FIG. 11A is the same as that of the AC signal, and the phase of the minimum point of the envelope is shown in FIG. It deviates from the zero point of the AC signal.

In the recording / reproducing apparatus for an optical recording medium shown in FIG. 8, the resistance value of the variable resistor 32 is periodically changed by the AC signal of a predetermined cycle oscillated by the oscillator 22 as described above. The first information signal is cross-talked into the second information signal based on the signal component obtained through the low-pass filter 27 after the signal output from the subtracter 34 is detected by the detection circuit 26 after being changed. A control signal (control voltage) for setting the resistance value of the variable resistor 32 that can be set not to be generated is generated by the control signal generation circuit 36 and supplied to the variable resistor 32.

That is, in the recording / reproducing apparatus for the optical recording medium of FIG. 8, the signal output from the low-pass filter 27 described above is exemplified by (c) of FIG. 11 or (e) of FIG. The signal 乗 算 is supplied to the multiplier 28, and the multiplier 28 multiplies the AC signal output from the oscillator 22 by the multiplier 28, and outputs the output signal from the multiplier 28 to the low-pass filter 2.
9, a control signal for setting the resistance value of the variable resistor 32 from the low-pass filter 29 so as not to crosstalk the first information signal in the second information signal. (Control voltage) is generated by the control signal generation circuit 36 and is supplied to the variable resistor 32. Therefore, in the recording / reproducing apparatus for the optical recording medium shown in FIG. 8, the objective lens 5 is set in a state where the first information signal is not cross-talked in the second information signal regardless of the various causes described above. (The position of the center of the reproduction light spot 6) can be automatically set to perform the reproduction operation.

[0064]

As is apparent from the above description, the recording / reproducing apparatus for an optical recording medium according to the present invention comprises:
An objective lens focuses an information track on which an information signal is recorded depending on the presence or absence of a mark and an optical recording medium (optical disc) on which an information signal is also recorded due to a displacement of recording information in a radial direction of the recording medium. By irradiating the read light spot for reproduction, the reproduction light including the above-mentioned respective recording information is generated from the optical disk and given to the photodetector, and the reproduction corresponding to the light intensity of the reproduction light from the optical disk according to the presence or absence of the mark on the optical disk. A signal is output from the photodetector as a first information signal. When the light spot for reproduction focused by the objective lens and the recording information on the recording medium are relatively displaced in the radial direction of the recording medium, the signal is output. The signal component in a predetermined frequency region in the difference signal between the two output signals output from the photodetector in a state in which In the case of using it, it is originally extremely difficult due to various causes such as the displacement of the optical head, the displacement of the photodetector, the imbalance of the gain of the difference signal processing system, the inclination of the optical disc surface in the radial direction, and the aging of the servo system. In order to prevent the S / N of the second information signal from deteriorating due to the crosstalk of the first information signal in the second information signal having a low signal level, the position of the optical axis of the objective lens (for reproduction) The position of the light spot) is set to a position in a direction and a distance respectively determined in the radial direction of the optical disc from the reference position of the tracking control operation so that the first information signal does not crosstalk in the second information signal. To prevent the first information signal component from crosstalking in the second information signal, or to generate a tracking error signal generated in the tracking control system in accordance with the amount of displacement of the optical axis of the objective lens. A signal for canceling the offset of the objective lens is generated according to the shift amount of the optical axis of the objective lens, and is supplied to the tracking control system, so that the tracking control is performed in a state where the shift amount of the optical axis of the objective lens is compensated. Is performed,
A state where the first information signal does not cause crosstalk in the second information signal or a detection of a radial inclination of the optical disk is performed, and the position of the light spot for reproduction (the objective The position of the optical axis of the lens) is shifted in the radial direction of the optical disc from the reference position of the tracking control operation, so that the first information signal component does not crosstalk in the second information signal, or is used for reproduction. The position of the spot of the light spot is shifted in the radial direction of the optical disk from the center position of the track according to the radial inclination of the optical disk, so that the first information signal component does not crosstalk in the second information signal. And a signal for canceling the offset of the tracking error signal generated in the tracking control system in accordance with the amount of displacement of the optical axis of the objective lens,
In a state where the tracking control is performed in a state where the deviation of the optical axis of the objective lens is compensated for by generating the deviation according to the deviation of the optical axis of the objective lens and supplying it to the tracking control system. A state where the first information signal does not cause crosstalk in the second information signal,
Further, the optical axis of the objective lens is displaced at a predetermined cycle in the radial direction of the optical recording medium, and the above-described condition is performed in a state where the optical axis of the objective lens is displaced at a predetermined cycle as described above. A signal indicating a state in which the first information signal is cross-talking is generated in the second information signal, and the optical axis of the objective lens is displaced in the radial direction of the optical recording medium by the signal indicating the state of cross-talk. Thereby, the first information signal is prevented from crosstalk in the second information signal, or the reproduction light spot focused by the objective lens and the recording information of the recording medium are recorded on the recording medium. The signal levels of two output signals output from the photodetector in a state where the magnitudes are complementarily changed when the relative displacement is made in the radial direction of the optical disc are detected by detecting the radial inclination of the optical disc. To the obtained signal And the first information signal is prevented from crosstalk in the second information signal, or the reproduction light spot focused by the objective lens and the recording information on the recording medium are changed. Are relatively displaced in the radial direction of the recording medium, the signal levels of two output signals output from the photodetector in a state in which the magnitudes are complementarily changed are changed at a predetermined cycle. In the changed state, a signal indicating a state where the first information signal is crosstalking is generated in the second information signal, and the second information signal is generated.
Output from the photodetector based on a signal indicating a state where the first information signal is cross-talking into the information signal of
According to the present invention, since the signal levels of the two output signals are relatively changed so that the first information signal does not cross-talk in the second information signal. Due to various causes, such as a position shift, a position shift of a photodetector, an imbalance of a gain of a difference signal processing system, a radial inclination of an optical disk surface, and a temporal change of a servo system,
Since the first information signal can be prevented from crosstalking in the second information signal including a signal component in a predetermined frequency domain in the difference signal between the two output signals output from the photodetector,
According to the present invention, the above-mentioned problems can be solved well.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a recording / reproducing apparatus for an optical recording medium according to the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a recording / reproducing apparatus for an optical recording medium according to the present invention.

FIG. 3 is a block diagram illustrating a schematic configuration of a recording / reproducing apparatus for an optical recording medium according to the present invention.

FIG. 4 is a block diagram showing a schematic configuration of a recording / reproducing apparatus for an optical recording medium according to the present invention.

FIG. 5 is a block diagram showing a schematic configuration of a recording / reproducing apparatus for an optical recording medium according to the present invention.

FIG. 6 is a block diagram showing a schematic configuration of an optical recording medium recording / reproducing apparatus of the present invention.

FIG. 7 is a block diagram showing a schematic configuration of a recording / reproducing apparatus for an optical recording medium according to the present invention.

FIG. 8 is a block diagram showing a schematic configuration of a recording / reproducing apparatus for an optical recording medium according to the present invention.

FIG. 9 is a diagram used for explaining the operation of the recording / reproducing apparatus for an optical recording medium according to the present invention.

FIG. 10 is a diagram used for explaining the operation of the recording / reproducing apparatus for an optical recording medium according to the present invention.

FIG. 11 is a diagram used to explain the operation of the optical recording medium recording / reproducing apparatus of the present invention.

[Explanation of symbols]

D: optical recording medium (optical disk), PD1, PD2: light detection unit, 1: light source, 2: collimating lens, 3: beam splitter, 4: reflecting mirror, 5: objective lens, 6: optical disk D was irradiated Reproduction light spot, 7 information track, 8 actuator of automatic control system, 9 photodetector,
9a: boundary line between two light detection units, 10, 25, 34: subtractor, 11: band-pass filter, 13, 18: adder, 1
5, 27, 29: low-pass filter, 16: tracking control circuit, 19: drive motor, 20: tilt sensor, 2
2 oscillator, 23 lens position sensor, 24, 31 control circuit, 28 multiplier, 30 lens shift control circuit
32: variable resistor, 33: resistor, 36: control signal generation circuit, 37: offset voltage supply circuit,

Claims (8)

(57) [Claims] 1. An optical recording medium having an information track on which an information signal is recorded depending on the presence or absence of a mark and also recording an information signal by displacement of recording information in a radial direction of the recording medium is provided. A reproduction light including the respective record information obtained by irradiating a reproduction light spot focused by a lens is supplied to at least one photodetector, and the presence or absence of a mark is determined based on an output signal from the photodetector. Means for obtaining a first information signal corresponding to the light intensity of the recording medium, and means for obtaining a second information signal corresponding to the displacement of the recording information in the radial direction of the recording medium based on the output signal from the photodetector. A recording / reproducing apparatus for an optical recording medium, comprising: a tracking control operation of an optical axis of an objective lens so that the first information signal does not crosstalk in the second information signal. Recording / reproducing apparatus for an optical recording medium, comprising means for displacing the optical recording medium in a radial direction from the reference position of (1). 2. An optical recording medium having an information track on which an information signal is recorded depending on the presence or absence of a mark and recording an information signal by a displacement of the recording information in a radial direction of the recording medium is provided. A reproduction light including the respective record information obtained by irradiating a reproduction light spot focused by a lens is supplied to at least one photodetector, and the presence or absence of a mark is determined based on an output signal from the photodetector. Means for obtaining a first information signal corresponding to the light intensity of the recording medium, and means for obtaining a second information signal corresponding to the displacement of the recording information in the radial direction of the recording medium based on the output signal from the photodetector. A recording / reproducing apparatus for an optical recording medium, comprising: a tilt state detecting means for obtaining a signal indicating an amount of tilt in a radial direction on a surface of the optical recording medium; and No. Means for displacing the optical axis of the objective lens from the reference position of the tracking control operation in the radial direction of the optical recording medium based on the output signal from the tilt state detecting means so that the information signal of No. 1 does not cause crosstalk. And a recording / reproducing apparatus for an optical recording medium. 3. An optical recording medium having an information track on which an information signal is recorded according to the presence or absence of a mark and recording an information signal by displacement of the recording information in a radial direction of the recording medium is provided. A reproduction light including the respective record information obtained by irradiating a reproduction light spot focused by a lens is supplied to at least one photodetector, and the presence or absence of a mark is determined based on an output signal from the photodetector. Means for obtaining a first information signal corresponding to the light intensity of the recording medium, and means for obtaining a second information signal corresponding to the displacement of the recording information in the radial direction of the recording medium based on the output signal from the photodetector. A recording / reproducing apparatus for an optical recording medium, comprising: means for displacing the optical axis of the objective lens in a radial direction of the optical recording medium at a predetermined cycle; and Forecast In a state where the second information signal is displaced at a predetermined period, the state of the crosstalk of the first information signal into the second information signal is determined based on the signal output from the means for obtaining the second information signal. Means for generating a signal indicative of the state of the crosstalk,
Means for displacing the optical axis of the objective lens from the reference position of the tracking control operation in the radial direction of the optical recording medium so that the first information signal does not cause crosstalk in the information signal. A recording / reproducing device for a recording medium. 4. An optical recording medium having an information track on which an information signal is recorded depending on the presence or absence of a mark and recording an information signal by a displacement of recording information in a radial direction of the recording medium is provided. A reproduction light including the respective record information obtained by irradiating a reproduction light spot focused by a lens is supplied to at least one photodetector, and the presence or absence of a mark is determined based on an output signal from the photodetector. Means for obtaining a first information signal corresponding to the light intensity of the recording medium, means for obtaining a second information signal corresponding to the displacement of the recorded information in the radial direction of the recording medium based on the output signal from the photodetector, A recording / reproducing apparatus for an optical recording medium including a control system, wherein the optical axis of the objective lens is controlled so that the first information signal does not crosstalk in the second information signal. Means for radially displacing the optical recording medium from the reference position of the tracking control operation,
Means for operating a tracking control system such that a tracking error becomes zero in a state where the optical axis of the objective lens is displaced in the radial direction of the optical recording medium by the operation of the displacement means. Recording / reproducing apparatus for dynamic recording media. 5. An optical recording medium having an information track on which an information signal is recorded depending on the presence / absence of a mark and recording an information signal by displacement of recording information in a radial direction of the recording medium is provided. A reproduction light including the respective record information obtained by irradiating a reproduction light spot focused by a lens is provided to at least one photodetector, and the presence or absence of a mark is determined based on an output signal from the photodetector. Means for obtaining a first information signal corresponding to the light intensity of the recording medium, a second information signal corresponding to the displacement of the recording information in the radial direction of the recording medium based on the output signal from the photodetector, and a tracking control system. A recording / reproducing apparatus for an optical recording medium, comprising: means for obtaining a tilt state detecting means for obtaining a signal indicating an amount of tilt in a radial direction on a board surface of the optical recording medium; and The optical axis of the objective lens is optically moved from the reference position of the tracking control operation based on the output signal from the tilt state detecting means so that the first information signal does not crosstalk in the second information signal. Means for displacing the recording medium in the radial direction, and tracking control such that the tracking error becomes zero in a state where the optical axis of the objective lens is displaced in the radial direction of the optical recording medium by the operation of the displacing means. Recording / reproducing apparatus for an optical recording medium, comprising: means for operating a system. 6. An optical recording medium having an information track on which an information signal is recorded depending on the presence or absence of a mark and recording an information signal by a displacement of recording information in a radial direction of the recording medium is provided. A reproduction light including the respective record information obtained by irradiating a reproduction light spot focused by a lens is provided to at least one photodetector, and the presence or absence of a mark is determined based on an output signal from the photodetector. Means for obtaining a first information signal corresponding to the light intensity of the recording medium, means for obtaining a second information signal corresponding to the displacement of the recording information in the radial direction of the recording medium based on the output signal from the photodetector, A recording / reproducing apparatus for an optical recording medium comprising a control system, wherein an optical axis of the objective lens is predetermined in a radial direction of the optical recording medium from a reference position of the tracking control operation. Means for displacing at a given cycle;
In a state where the optical axis of the objective lens is displaced at a predetermined cycle, the first information into the second information signal is obtained based on the signal output from the means for obtaining the second information signal. Means for generating a signal indicating the state of crosstalk of the information signal, and the signal indicating the state of crosstalk, so that the first information signal is not crosstalked in the second information signal. Means for displacing the optical axis of the lens from the reference position of the tracking control operation in the radial direction of the optical recording medium, and displacing the optical axis of the objective lens in the radial direction of the optical recording medium by the operation of the displacement means. In the state,
Means for operating a tracking control system so that a tracking error becomes zero. 7. An optical recording medium having an information track on which an information signal is recorded depending on the presence or absence of a mark and recording an information signal by a displacement of recording information in a radial direction of the recording medium is provided. A reproduction light including the respective record information obtained by irradiating a reproduction light spot focused by a lens is provided to at least one photodetector, and the presence or absence of a mark is determined based on an output signal from the photodetector. Means for obtaining a first information signal corresponding to the light intensity due to the above, and the magnitude of the signal complementarily changes in accordance with the radial displacement of the recording light medium for the reproduction focused by the objective lens. Means for obtaining a second information signal by a difference signal between two output signals obtained from the photodetector in a state in which the optical recording medium is in On the board And a photodetector used to obtain the second information signal are output in a state where the magnitudes are complementary to each other. Means for relatively changing the signal levels of the two output signals based on the output signal from the tilt state detecting means. 8. An optical recording medium having an information track on which an information signal is recorded depending on the presence or absence of a mark and recording an information signal by a displacement of recording information in a radial direction of the recording medium is provided. A reproduction light including the respective record information obtained by irradiating a reproduction light spot focused by a lens is provided to at least one photodetector, and the presence or absence of a mark is determined based on an output signal from the photodetector. Means for obtaining a first information signal corresponding to the light intensity due to the above, and the magnitude of the signal complementarily changes in accordance with the radial displacement of the recording light medium for the reproduction focused by the objective lens. Means for obtaining a second information signal by a difference signal between two output signals obtained from the photodetector in a state in which the optical recording medium is in a state where the second signal is output. Information signal Output from the photodetector used to obtain it in a state where the magnitudes are complementary
Means for relatively changing the signal levels of the two output signals at a predetermined period, and two output signals output from the photodetector in a state where the magnitudes are complementarily changed. In a state where the level is relatively changed at a predetermined cycle, the first information in the second information signal is based on the signal output from the means for obtaining the second information signal. Means for generating a signal indicative of the state of signal crosstalk, and two outputs which are output in a state where their magnitudes are complementarily changed from the photodetector used for obtaining the second information signal. Means for relatively changing the signal level of the signal based on the signal indicating the state of the crosstalk.