JP2000048489A - Optical disk device, super-high resolution optical disk device and dwdd optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reproducing quality by extracting external disturbance information from a reproducing signal to reduce external disturbances and securing a sufficient reproducing margin. SOLUTION: An external disturbance information extracting means 11 extracts external disturbance information regarding external disturbances contained in a reproducing signal reproduced from an optical disk 1. An external disturbance detecting means 12 detects the external disturbances from the external disturbance information. An optimal point setting means 13 sets an optimal point for canceling the detected external disturbances. An external disturbance control means 14 controls a parameter regarding the reproducing condition of the optical disk 1 to approach the optimal point and then cancels the external disturbances.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical disk device, a super-resolution optical disk device and a DWDD (Domain Wall Displac).
ement Detection) Regarding optical disk devices, in particular, optical disk devices that record and reproduce information on optical disks,
For a super-resolution optical disc device that records and reproduces information on a super-resolution optical disc, and for a DWDD optical disc,
The present invention relates to a DWDD optical disk device for recording and reproducing information.

[0002]

2. Description of the Related Art With the rapid progress of digitization of moving images and compression coding techniques, demands for high-density recording on optical discs are increasing.

In recent years, when increasing the recording density of an optical disc, a short wavelength semiconductor laser or SHG (Second Harmonic
Generation) The recording density is increased by miniaturizing the condensing spot system of the optical head by using an optical element.

On the other hand, as a high-density recording, a magneto-optical disk MS having a recording layer and a reproducing layer having in-plane magnetization is used.
An R (Magnetic Super Resolution) type super-resolution optical disk has been proposed.

[0005] In this super-resolution optical disk, a light beam is irradiated from the reproduction layer side to raise the temperature of the reproduction layer in the irradiation area. Then, the reproducing layer of only the detection port (aperture) which has risen to a predetermined temperature or higher shifts from in-plane magnetization to perpendicular magnetization in which the magnetism of the corresponding recording layer has been transferred.

[0006] This makes it possible to reproduce a recording mark smaller than the spot system of the focused beam.

[0007]

However, in the above-mentioned conventional technology for miniaturizing the condensing spot system, the smaller the condensing spot system is, the more the small aberration caused by disturbance can be reproduced. Since this affects the signal, there is a problem in that a sufficient reproduction margin of the system (a measure indicating whether the system can achieve an error rate equal to or less than an allowable error rate) cannot be sufficiently secured.

In addition, the conventional super-resolution optical disc has a problem that the size of the aperture determined by the reproduction power and the media sensitivity affects the signal characteristics, so that it is susceptible to power fluctuations and media sensitivity unevenness.

Disturbance information relating to disturbances causing such spot aberrations and aperture fluctuations can be recognized from the level distribution of a signal sampled from a reproduced signal, the level of a specific pattern signal, and the like. Disturbance information was not used effectively during playback.

The present invention has been made in view of the above points, and an optical disk which extracts disturbance information from a reproduction signal to reduce disturbance, secure a sufficient reproduction margin, and improve reproduction quality. It is intended to provide a device.

Another object of the present invention is to provide a super-resolution optical disc apparatus which extracts disturbance information from a reproduction signal to reduce disturbance, secure a sufficient reproduction margin, and improve reproduction quality. It is to be.

Still another object of the present invention is to provide a DWDD optical disk apparatus which extracts disturbance information from a reproduction signal to reduce disturbance, secure a sufficient reproduction margin, and improve reproduction quality. It is.

[0013]

According to the present invention, in order to solve the above-mentioned problems, in an optical disk apparatus for recording and reproducing information on and from an optical disk, the present invention relates to disturbances included in a reproduction signal reproduced from the optical disk. Disturbance information extraction means for extracting disturbance information, disturbance detection means for detecting a disturbance from the disturbance information, optimum point setting means for setting an optimum point for canceling the detected disturbance, and parameters relating to reproduction conditions of the optical disc. Disturbance elimination control means for controlling to approach the optimum point and eliminating the disturbance,
An optical disk device characterized by having:

Here, the disturbance information extracting means extracts disturbance information relating to a disturbance included in a reproduction signal reproduced from the optical disk. The disturbance detection means detects a disturbance from the disturbance information. The optimum point setting means sets an optimum point for canceling the detected disturbance. The disturbance erasure control means erases the disturbance by controlling the parameters relating to the reproduction condition of the optical disk so as to approach the optimum point.

In a super-resolution optical disc apparatus for recording and reproducing information on and from a super-resolution optical disc, the reproduction data reproduced from the super-resolution optical disc is sampled by the reproduction power of a light beam. Sampling data generating means for generating data; disturbance detecting means for detecting a disturbance from the sampling data; optimum point setting means for setting an optimum point of a parameter for canceling the detected disturbance; and the disturbance and the optimum From the point, a band dividing means for decomposing the band of the reproduction data into a DC component and a low-frequency component, and a high-frequency component, based on the DC component and the low-frequency component, such that the parameter approaches the optimum point. Reproducing power control means for controlling the reproducing power; and the parameter based on the high-frequency component. So as to approach the optimum point, and Ekoraizu means for outputting the reproduced data by performing waveform adjustment, super-resolution optical disk apparatus characterized by having provided.

Here, the sampling data generating means includes:
The reproduction data reproduced from the super-resolution optical disk is sampled by the reproduction power of the light beam to generate sampling data. The disturbance detecting means detects a disturbance from the sampling data. The optimum point setting means sets an optimum point of a parameter for canceling the detected disturbance. The band dividing means decomposes the band of the reproduction data into a DC component, a low-frequency component, and a high-frequency component from the disturbance and the optimum point. The reproduction power control means controls the reproduction power based on the DC component and the low frequency component so that the parameter approaches the optimum point. The equalizing means adjusts the waveform based on the high-frequency component so that the parameter approaches the optimum point, and outputs reproduced data.

Further, in a DWDD optical disk apparatus for recording and reproducing information on and from a DWDD optical disk,
Timing interval change detecting means for detecting a change in timing interval, which occurs when a magnetic domain shift occurs at the leading end and the trailing end of the waveform of the reproduced data, and detecting the amplitude difference between the short mark and the long mark of the reproduced data. A DWDD optical disk device is provided, comprising: an amplitude difference detection unit; and a reproduction control unit that performs reproduction control so as to erase the change in the timing interval and the amplitude difference.

Here, the timing interval change detecting means includes:
A change in timing interval that occurs when a magnetic domain shift occurs at the leading end and the trailing end of the waveform of the reproduced data is detected. The amplitude difference detecting means detects an amplitude difference between the short mark and the long mark of the reproduced data. The reproduction control means performs reproduction control so as to eliminate the change in the timing interval and the amplitude difference, respectively.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the principle of an optical disk device according to the present invention. The optical disc device 10 records and reproduces information on and from the optical disc 1.

The disturbance information extracting means 11 extracts disturbance information relating to disturbance contained in a reproduction signal reproduced from the optical disk 1 through the head 2. Here, the disturbance is MT
F (Modulation Transfer Function: frequency characteristics of a recording / reproducing system having high-frequency attenuation characteristics), light beam distortion, asymmetry (pit length change), and the like.

In the case where the MTF is reduced as the disturbance information, it corresponds to the amplitude ratio between the short mark and the long mark, the slope of the zero cross (peak point of the reproduced waveform), the level of the unsaturated signal, and the like. Further, in the case of the light beam distortion, it corresponds to the difference between the rise and fall of the zero-cross slope, the shoulder level of the unsaturated signal, and the like. Further, in the case of asymmetry, it corresponds to a multi-level central value or the like.

The disturbance detecting means 12 detects a disturbance from the disturbance information. The optimum point setting means 13 sets an optimum point for canceling the detected disturbance. This optimum point may be set in advance, or if feedback control is performed while monitoring the reproduction signal, only the initial value may be set.

The disturbance erasure control means 14 controls parameters relating to the reproduction conditions of the optical disk to approach the optimum point and erase the disturbance. For example, the causes of the decrease in the MTF include a focus offset, a radial tilt, and an offset from an optimum point of the reproduction power. Therefore, these are controlled as parameters of the reproduction condition to approach the optimum point and eliminate the MTF decrease.

The tangential tilt and the like correspond to the parameters of the light beam distortion. Further, as a parameter of the asymmetry, the strength of the leakage magnetic field or the like corresponds. The figure shows that the disturbance power is controlled by controlling the reproduction power.

Next, the operation will be described.
It is a flowchart which shows the operation | movement procedure of reduction control. [S1] The disturbance information extracting means 11 extracts at least one of the amplitude ratio of the short mark and the long mark, the slope of the zero cross, and the level of the unsaturated signal from the reproduction signal as the disturbance information. [S2] The disturbance detection means 12 detects that the MTF has dropped from the disturbance information in step S1. [S3] The disturbance elimination control unit 14 controls at least one of the focus offset, the radial tilt, and the reproduction power so as to approach the optimum point, and eliminates (adjusts) the MTF decrease which is a disturbance.

FIG. 3 is a flowchart showing the operation procedure of the light beam distortion control. [S10] The disturbance information extracting means 11 extracts at least one of the difference between the rise and fall of the zero-cross slope and the shoulder level of the unsaturated signal as disturbance information from the reproduced signal. [S11] The disturbance detection means 12 detects how much light beam distortion has occurred from the disturbance information in step S10. [S12] The disturbance elimination control unit 14 eliminates (adjusts) the light beam distortion, which is disturbance, by controlling the tangential tilt to approach the optimum point.

FIG. 4 is a flowchart showing the operation procedure of the asymmetry control. [S20] The disturbance information extracting means 11 extracts a multi-level center value from the reproduced signal as disturbance information. [S21] The disturbance detecting means 12 detects the degree of asymmetry from the disturbance information in step S20. [S22] The disturbance elimination control unit 14 eliminates (adjusts) asymmetry, which is a disturbance, by controlling the leakage magnetic field intensity to approach an optimum point.

As described above, the optical disk apparatus 10 of the present invention extracts disturbance information included in a reproduction signal, controls parameters relating to reproduction conditions of the optical disk 1, and deletes the disturbance detected from the disturbance information. The configuration was adopted.
As a result, various signal deteriorations can be compensated, and high-density and stable recording and reproduction can be performed.

Next, the super-resolution optical disk device of the present invention will be described. FIG. 5 is a diagram illustrating the principle of the super-resolution optical disc apparatus according to the present invention. The super-resolution optical disk device 20 is a CAD (Ce
Information is recorded / reproduced to / from the super-resolution optical disc 1a of the nterAperture Detection).

The sampling data generation means 21 samples the reproduction data reproduced from the super-resolution optical disk 1a by using the reproduction power of the light beam, and generates sampling data.

The disturbance detecting means 22 detects at least one of MTF reduction, light beam distortion and asymmetry from the sampling data as a disturbance. Optimal point setting means 23
Sets the optimal point of the parameter for canceling the detected disturbance. For example, the optimum point is recorded in the memory of the drive and the control information of the medium.

Also, the optimum point may be set adaptively so that the jitter is minimized at the time of data detection. The band dividing means 24 decomposes the band of the reproduced data into a DC component, a low-frequency component, and a high-frequency component from the disturbance and the optimum point.

The reproduction power control means 25 controls the reproduction power based on the DC component and the low frequency component so that the parameter approaches the optimum point. The ecorizing means 26
Based on the high-frequency component, waveform adjustment is performed so that the parameter approaches the optimum point, and reproduced data is output.

If the disturbance is related to the tilt, the focus tilt control means 29 controls the focus tilt based on the DC component and the low frequency component so as to eliminate the disturbance.

Next, the operation will be described. FIG. 6 is a flowchart showing the operation procedure of the super-resolution optical disc reproducing apparatus 20. [S30] The light beam output means 28 (corresponding to a laser diode or the like) outputs a light beam. [S31] The optical / electrical conversion means 27 (corresponding to a photodiode or the like) performs optical / electrical conversion of information read from the super-resolution optical disk 1a through the head 2, and generates a read signal. [S32] The equalizing means 26 adjusts the waveform of the read signal and outputs reproduced data. [S33] The sampling data generation means 21 samples the reproduction data reproduced from the super-resolution optical disc 1a by using the reproduction power of the light beam, and generates sampling data. [S34] The disturbance detecting means 22 detects a disturbance from the sampling data. [S35] The band splitting unit 24 calculates, based on the disturbance and the optimum point,
The band of the reproduction data is decomposed into a DC component, a low frequency component, and a high frequency component. [S36] The reproduction power control means 25 controls the reproduction power of the light beam based on the DC component and the low frequency component so that the parameter approaches the optimum point. Also, the reproducing power of the light beam is controlled by using the APC monitor signal from the optical / electrical conversion means 27. [S37] The equalizing means 26 adjusts the waveform based on the high-frequency component so that the parameter approaches the optimum point, and outputs reproduced data. [S38] If the disturbance is related to the tilt, the focus tilt control means 29 controls the focus tilt based on the DC component and the low frequency component so as to eliminate the disturbance.

Next, the details of the super-resolution optical disk device 20 will be described. When the super-resolution optical disc 1a is inserted into the super-resolution optical disc device 20, the reproduction signal already written on the test track or the newly written signal is converted into correction parameters such as focus offset, reproduction power, tilt, and reproduction magnetic field. Is monitored while changing step by step.

The data at this time may be random data. From the signal sampled by the PLL clock generated from the data, the difference between the sampled data before and after the zero cross is obtained, and normalized by the difference between the longitudinal marks (111...) And (000...).

This value represents a step response from (111...) To (000...) And indicates MTF which is a transfer coefficient of the system. If the rising and falling values are different, the ratio indicates signal distortion.

FIG. 7 is a diagram showing an evaluation value of disturbance from a sampling data waveform. From the sampling data waveform as shown in the figure, the MTF evaluation value: M, the light beam distortion: Y,
Asymmetry: Z is represented by the following equation.

[0040]

M = (Xdown + Xup) / 2XL (1)

[0041]

Y = (Xdown−Xup) / (Xdown + Xup) (2)

[0042]

## EQU3 ## Z = (X1 + X2 + X6 + X7) / 4-XL / 2 (3) Then, the MTF of the average value of the sampling data before and after the zero-cross point or the set value of each parameter at which the distortion is optimized is recorded. Each control item is controlled so as to approach the optimum point.

FIG. 8 is a diagram showing the relationship between the reproduction power and the optimum point. The vertical axis represents BER (bit error), and the horizontal axis represents reproduction power. The point P1 at which the BER is minimum on M, which is the MTF evaluation value, is determined as the optimum point.

FIG. 9 is a diagram showing the relationship between the tangential tilt and the optimum point. The ordinate is the BER, and the abscissa is the tilt angle. The point P2 at which the BER is minimized on the light beam distortion evaluation value Y is determined as the optimum point.

FIG. 10 is a diagram showing the relationship between asymmetry and the optimum point. The ordinate is the BER, and the abscissa is the reproducing magnetic field. The point P3 at which the BER is minimized on Z, which is the asymmetry evaluation value, is determined as the optimum point.

The setting of the optimum point is recorded in the memory of the drive or the control information of the medium, if known, and is referred to. Alternatively, the optimum control value for data detection may be set as the optimum point while checking error jitter and the like during step control by the drive itself.

Then, even after the initial setting, the MT in the reproduction data is
While monitoring F or distortion, control is added so as to reach the target optimum point. Regarding this control, an effect can be obtained even with a normal disc other than the MSR. In addition, since there is a variation in the orbit, distortion may be fed back to the coefficient balance of the equalizer coefficient.

As described above, the super-resolution optical disc apparatus 20 of the present invention extracts the disturbance information included in the reproduction signal, and controls the parameters related to the reproduction conditions of the super-resolution optical disc 1a by controlling the DC, the low level of the reproduction data, The disturbance is canceled based on the frequency component and the high frequency component. As a result, the disturbance element can be adaptively erased, so that a sufficient reproduction margin can be secured and the reproduction quality can be improved.

Next, the DWDD optical disk device 30 of the present invention
Will be described. FIG. 11 is a diagram illustrating the principle of the DWDD optical disk apparatus according to the present invention. DWDD (magnetic domain expansion reproduction method)
The optical disk device 30 records and reproduces information on the DWDD optical disk 1b.

The timing interval change detecting means 31 detects a change in the timing interval caused when a magnetic domain shift occurs at the leading end and the trailing end of the reproduced waveform due to the reproduction power or the tilt defocus.

The amplitude difference detecting means 32 detects an amplitude difference between the short mark and the long mark of the reproduced data, which occurs when the reproducing power is reduced. The reproduction control unit 33 controls the reproduction power and the tilt defocus so as to eliminate the change in the timing interval and the amplitude difference, respectively.

Next, the details of the DWDD optical disk device 30 will be described. FIG. 12 is a diagram showing a change in timing of a reproduction waveform. When a magnetic domain shift occurs at the leading end and the trailing end of the reproduced waveform due to the reproducing power or the tilt defocus, the timing interval changes as shown in the figure.

The timing interval change detecting means 31 detects such a change in the timing interval. FIG. 13 is a diagram showing a decrease in the MTF when the reproducing power decreases. The vertical axis is MTF, and the horizontal axis is spatial frequency. As shown in the figure, when the reproduction power decreases, the MTF decreases, and the operation shifts from the DWDD operation to the normal operation.

As described above, when the DWDD operation is incomplete, the frequency characteristic is no longer infinite, an amplitude difference between the short mark and the long mark appears, and the short mark amplitude decreases. Therefore, the amplitude difference detecting means 32 detects the amplitude difference between the short mark and the long mark of such reproduced data.

Then, the reproduction control means 33 controls the reproduction power tilt defocus to eliminate these disturbances. As described above, the DWDD optical disk device 30 of the present invention is configured to detect a change in the timing interval and a difference in mark amplitude to control the reproduction power fluctuation and the tilt defocus. As a result, the disturbance element can be adaptively erased, so that a sufficient reproduction margin can be secured and the reproduction quality can be improved.

[0056]

As described above, the optical disk apparatus of the present invention extracts disturbance information included in a reproduction signal, controls parameters relating to reproduction conditions of the optical disk,
The disturbance detected from the disturbance information is eliminated. As a result, a sufficient reproduction margin can be secured, and the reproduction quality can be improved.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating an operation procedure of MTF reduction control.

FIG. 3 is a flowchart illustrating an operation procedure of light beam distortion control.

FIG. 4 is a flowchart illustrating an operation procedure of asymmetry control.

FIG. 5 is a diagram illustrating the principle of a super-resolution optical disc apparatus according to the present invention.

FIG. 6 is a flowchart showing an operation procedure of the super-resolution optical disc reproducing apparatus.

FIG. 7 is a diagram showing an evaluation value of disturbance from a sampling data waveform.

FIG. 8 is a diagram showing a relationship between reproduction power and an optimum point.

FIG. 9 is a diagram showing a relationship between a tangential tilt and an optimum point.

FIG. 10 is a diagram showing a relationship between asymmetry and an optimum point.

FIG. 11 is a diagram illustrating the principle of a DWDD optical disk device according to the present invention.

FIG. 12 is a diagram showing a change in timing of a reproduction waveform.

FIG. 13 is a diagram showing a decrease in MTF when a reproduction power is decreased.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Head, 10 ... Optical disk apparatus, 11 ... Disturbance information extraction means, 12 ... Disturbance detection means, 13 ... Optimal point setting means, 14 ... Disturbance elimination control means.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D044 BC02 CC04 FG01 FG05 FG11 FG16 5D075 AA03 CC24 CD10 CD11 DD03 5D090 AA01 BB10 CC04 DD03 DD05 EE12 EE13 HH01 KK03

Claims (8)

[Claims] 1. An optical disc apparatus for recording and reproducing information on and from an optical disc, comprising: disturbance information extracting means for extracting disturbance information relating to disturbance included in a reproduction signal reproduced from the optical disc; Disturbance detection means for detecting a disturbance; optimum point setting means for setting an optimum point for canceling the detected disturbance; and controlling the parameters relating to the reproduction conditions of the optical disk to approach the optimum point to erase the disturbance. An optical disc device comprising: 2. The apparatus according to claim 1, wherein the disturbance detecting means includes:
2. The optical disk device according to claim 1, wherein at least one of MTF reduction, light beam distortion, and asymmetry is detected. 3. A super-resolution optical disc apparatus for recording and reproducing information on and from a super-resolution optical disc, wherein reproduction data reproduced from the super-resolution optical disc is sampled by a reproduction power of a light beam. Sampling data generating means for generating data; disturbance detecting means for detecting a disturbance from the sampling data; optimum point setting means for setting an optimum point of a parameter for canceling the detected disturbance; and the disturbance and the optimum From the point, a band dividing means for decomposing the band of the reproduction data into a DC component, a low frequency component, and a high frequency component, based on the DC component and the low frequency component, so that the parameter approaches the optimum point. Based on the high-frequency component, the parameter is determined based on the reproduction power control unit that controls the reproduction power. A super-resolution optical disc device comprising: an equalizing means for adjusting the waveform so as to approach the optimum point and outputting the reproduced data. 4. The disturbance detection means according to claim 1, wherein
4. The super-resolution optical disk device according to claim 3, wherein at least one of MTF reduction, light beam distortion, and asymmetry is detected. 5. The super-resolution optical disc apparatus according to claim 3, wherein said optimum point setting means adaptively sets said optimum point so as to minimize jitter when data is detected. 6. The super-resolution system according to claim 3, further comprising a focus tilt control means for controlling a focus tilt so as to eliminate the disturbance based on the DC component and the low frequency component. Optical disk device. 7. A DWDD optical disk apparatus for recording and reproducing information on and from a DWDD optical disk detects a change in a timing interval that occurs when a magnetic domain shift occurs at a leading end and a trailing end of a waveform of reproduced data. Timing interval change detection means; amplitude difference detection means for detecting an amplitude difference between short marks and long marks of the reproduction data; reproduction control for performing reproduction control so as to eliminate the change in the timing interval and the amplitude difference, respectively. A DWDD optical disc device comprising: 8. The DWDD optical disk device according to claim 7, wherein said reproduction control means performs reproduction control of reproduction power and tilt defocus.