JPH0831093A - Optical disk medium and device - Google Patents

Abstract

PURPOSE:To improve reproduced signal quality and to obtain a high density by reproducing a learning area on an optical disk medium and adjusting a reproduced signal compensation characteristic so that an error becomes small. CONSTITUTION:A data area and the learning area are provided on the optical disk medium. The learning area are reproduced, and the learning data of a demodulation binarization data pattern through a modulation means 13, etc., are compared with a fixed teacher pattern by a comparison means 17. A component analysis means 33 according to the comparison result decides the reproduced signal compensation characteristic of a level characteristic and a phase characteristic so that the error becomes small to control a transversal filter 12 of an equivalent means through a control means 34. By adjusting the equivalent means by using the learning area, the reproduced signal quality is improved, and the high density is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information reproducing apparatus for recording / reproducing a digital signal, and more particularly to an optical disk medium for reproduction only.

[0002]

2. Description of the Related Art In recent years, an optical disk device has been put into practical use as an information storage / reproduction device having a large capacity and capable of exchanging media. In particular, with the progress of digital moving image compression technology, a technique capable of recording for 2 hours or more has been developed by compressing a digital moving image to a transfer rate of about 3 Mbps with a compact disk size having a diameter of about 120 mm. In such an optical disk device, it is required to achieve a recording capacity of 3 Gbytes or more on one side, which is about 0.3 bits / micron at a track pitch of about 0.8 microns in terms of recording density. This is to achieve the above linear density. The problem in achieving such a high recording density is to improve the S / N and the interference between the recording pits, and at the same time, to guarantee the signal quality against variations in the optical disc medium and the optical disc device. This is particularly due to defocus, off-track, tangential tilt (tilt in the recording track tangential direction), radial tilt (tilt in the disk radial direction), etc., which are typified by variations in the positional relationship between the optical head and the optical disk medium. It has been pointed out as a change in channel characteristics,
There is a demand for a device that has a small increase in error rate due to these factors.

An example of the above-mentioned conventional optical disk medium will be described below with reference to the drawings.

FIG. 7 is a diagram showing a recording area of a conventional optical disc medium, and FIG. 8 is a configuration diagram of an optical disc device. FIG. 9 is a block diagram of the binarizing means of FIG. In FIG. 7, 1 is an optical disc medium, and 2 is a data area in which digital data is recorded. 3 is a pit and 4 is a recording track. In FIG. 8, 5 is a semiconductor laser (LD), 6
Is an optical system, 7 is a light spot, 8 is a pin photodiode (PD), 9 is a preamplifier, 10 is a binarizing means, 11 is a SYNC detecting means, 12 is a demodulating means, and 13 is an error correcting means (ECC). . In FIG. 9, 14 is a transversal filter, 15 is comparison means, 16 is subtraction means, 17
Is a learning means, 18 is a phase locked loop (PLL), and 19 is a judging means.

In FIG. 7, in the optical disk medium 1, a compressed audio or image information program is digitally modulated as digital data, and a row of pits 3 is formed in a concavo-convex pattern so that the length changes according to a predetermined rule. Are arranged spirally from the inner peripheral portion toward the outer peripheral portion so as to form the recording track 4, and are recorded in the entire data area so that the light spot can be tracked by this arrangement.

In FIG. 8, the output light of the semiconductor laser 5 is optically processed by the optical system 6 and condensed as a light spot 7 on the optical disc medium 1, and the reflected light is incident on the pin photodiode 8. The preamplifier 9 amplifies the reflected light change detected by the pin photodiode 8, and as a result, outputs a reproduction signal that changes according to the pit length on the optical disc medium. The binarizing means 10 binarizes the reproduction signal obtained as an analog signal and identifies it as the read data recorded on the optical disc medium, and the SYNC detecting means 11 synchronizes the read data with the SYNC signal.
The C pattern is detected and the SYNC detection result is output, the demodulation means 12 outputs the demodulation data by bit synchronization of the read data according to the SYNC detection result, and the error correction means 13
Performs error correction processing on the demodulated data and outputs it as error-free digital data.

In FIG. 9, the transversal filter 1
Reference numeral 4 denotes a waveform equalizer which is composed of a delay line, a multiplier and an adder, delays the input signal by a plurality of delay amounts, multiplies each delayed signal by an appropriate coefficient and adds the multiplied signals. The comparison means 15 is a comparator that operates so as to output the sign of the output of the transversal filter 14 as a binary signal. The subtracting means 16 takes the difference between the binary signal and the output of the transversal filter 14 and outputs it as an equalization error. The learning means 17 is a decision feedback type learning operation in which characteristics are adjusted so as to reduce the energy of the equalization error signal by changing the coefficient of the transversal filter 14 based on the obtained equalization error signal. I do.
The PLL 18 extracts the clock component from the binary signal and outputs it. The judging means 19 is a D-type flip-flop, which synchronizes the binary signal with the reproduction clock and outputs it as read data.

Since the reproduction characteristic of a digital recording apparatus such as an optical disk is generally a low-pass filtering characteristic, the higher the recording density, the more the high-frequency component necessary for reproducing the digital signal is suppressed and the reproduction signal quality deteriorates. The waveform equalization characteristic realized by the transversal filter 14 in order to compensate for this low-pass filtering characteristic requires the gain to have a small characteristic in the low frequency range and a large characteristic in the high frequency range, and the frequency characteristic is also the reproduction characteristic. Need to be decided accordingly. In the above-described series of operations, the teacher signal for learning of the transversal filter 14 is a square wave signal binarized by the comparing means 15, and the learning means 17 outputs the output of the transversal filter 14 to this square wave. The coefficient of the transversal filter 14 is adjusted so as to approach the signal.

As described above, in the optical disk device using the conventional optical disk medium, waveform equalization is performed by the transversal filter, and the reproduction characteristic is compensated by adjusting the coefficient to improve reliability. . In particular,
The binarization result is the same as the original recorded digital data, ignoring the occurrence of an error, and learning is performed using this as the teacher data to convert the signal before binarization into the signal after binarization. It is possible to automatically adjust the waveform equalization characteristics in a manner similar to. This has the feature that learning can be performed at any time even during the reproducing operation after the optical disk medium is mounted in the optical disk device.

[0010]

Attention has been paid to the fact that media can be exchanged as a feature of optical discs, and with the progress of higher density, the compensation performance against variations as described above has become a problem. However, in the above-mentioned configuration, when the density is further increased, the dispersion between the optical disc media or between the devices becomes large, and the reliability becomes low in the reproduction signal processing of a single characteristic. Even in a system by automatic equalization that adaptively adjusts, it is difficult to give a good initial characteristic because the detection error becomes large as a result of binarization, and the reliability of the teacher data decreases even during learning. However, there was a problem that learning became difficult.

Even after the disc is mounted, for example,
Due to the difference between the inner and outer circumferences of the disc, in addition to variations in the condition of the molding and reflection film of the disc, the parallelism between the optical head and the disc shifts due to the warp of the disc, etc. This occurs, and the quality of the reproduced signal deteriorates due to this tilt. In particular, since the center mounting is performed by using the center hole when mounting the disc, the tilt may change between the inner peripheral portion and the outer peripheral portion, and the equalization characteristics required when different areas are accessed suddenly change. This made the error bigger and made learning more difficult.

In view of the above problems, the present invention provides an optical disk medium having a learning area for recording preset learning data in an area different from the data area for recording information. By comparing the reproduction signal of the area with a predetermined teacher data pattern, automatic adjustment by learning of reproduction signal processing is enabled.

[0013]

In order to solve the above problems, an optical disk medium of the present invention is an optical disk medium having a learning area, an optical means for reproducing information recorded on the optical disk medium, and reproduced information. A reproduction amplification means for converting the electric signal into an electric signal and outputting a reproduction signal, a component analysis means for analyzing the frequency component of the reproduction signal, an equalization means for equalizing the reproduction signal whose characteristics are controlled by the control signal, and a component It is composed of control means for controlling the equalization characteristic according to the output of the analysis means.

Further, the component analysis means separately obtains the level resolution and the phase resolution, and the control means further comprises a configuration for controlling the characteristics of the equalization means by appropriate conversion from the level resolution and the phase resolution.

At the same time, the optical disk medium of the present invention has the above-mentioned learning area, and the learning area has a teacher data pattern suitable for detecting the levels of a plurality of frequency components as a frequency resolution, and further suitable for detecting the phase. It has a teacher data pattern.

Further, the optical disc medium has a learning area set in each of the inner peripheral portion and the outer peripheral portion.

[0017]

According to the present invention, the compensation characteristics of the reproduced signal processing are learned by reproducing the learning area before the program is reproduced after the apparatus is mounted on the apparatus. It is intended to provide a highly reliable optical disc device that improves the error rate by compensating for a characteristic change due to the combination, and an optical disc medium therefor.

Specifically, the reproduced signal or the signal output from the equalizing means is analyzed and output as a frequency resolution signal,
This controls the characteristics of the equalizing means. Further, in the control, the level characteristic is controlled based on the level resolution.

In addition, by controlling the phase characteristic of the equalizing means so that the slopes of the rising edge and the falling edge of the equalized output coincide with each other, the shapes of the pit start end and the end end are not uniform, and the tangential tilt is generated. It is intended to reduce an increase in errors due to a defective edge of a reproduction signal due to.

Further, learning regions are provided in the inner and outer circumferences, and the results obtained by learning each area are stored, and the results of the inner and outer circumferences are interpolated to compensate the compensation characteristics of the entire circumference. Accordingly, the present invention provides an optical disc medium and a device for realizing highly reliable optical disc reproduction.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk medium and device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of an optical disk medium in an embodiment of the present invention. FIG. 2 is a detailed view of FIG. 1, FIG. 3 is a main part structural view of an optical disk device in an embodiment of the present invention, and FIG. FIG. 5 is a block diagram of the main part of FIG.
FIG. 3 is an explanatory diagram with second teacher data. In FIG. 1, 1
Is an optical disk medium. Reference numeral 2 is a data area, 31 is an inner peripheral learning area, and 32 is an outer peripheral learning area. In FIG. 3, 33 is a component analysis means and 34 is a control means. The whole of FIG. 3 constitutes the binarizing means in the optical disk device of FIG. FIG. 4 shows the configuration of the component analyzing means 33, in which 35 is differentiating means, 36 and 39.
Is a switch, 37 is an upper envelope detecting means, 38 is a lower envelope detecting means, 40 is a sampling means,
Reference numeral 41 is a gate generation means, and 42 is a calculation means. In the following, in the optical disc medium of the present invention, the same components as those in the conventional example are given the same numbers and their explanations are omitted. The functions and operations of the optical disc medium and the device configured as described above will be described below with reference to FIGS.

First, when the optical disc medium 1 is mounted in the optical disc device, the optical disc device accesses the learning area at the inner peripheral portion and starts the reproduction of the learning area 31. Is given, it is possible to learn the equalization characteristic with high accuracy. The equalization characteristic obtained after this learning operation is fixed and the program in the data area is reproduced. In the optical disc medium 1, a synchronization signal (SYNC) is provided for each frame having data of 42 bytes as one period as shown in FIG. It is written so that it becomes one sector. When playing this SYNC is S
It is detected by the YNC detecting means 11 and the demodulation is synchronized. Although this SYNC is written in the learning area as well, repetitive signals of frequencies f1 and f2 are alternately written for each frame in a predetermined track in the learning area as shown in FIG. 4A.

Here, f1 is a frequency when the shortest pit and space to be reproduced are continuous, and f2 is a frequency shown in FIG.
This is the frequency when marks and spaces longer than the light spot diameter are continuous as shown in (b). As shown in FIG. 2 (e), the reproduction level of the pit is correctly obtained by the reproduction signal in the case of longer than the spot diameter, but the reproduction level of the shortest pit becomes small due to the inter-pit interference. This becomes remarkable as the density becomes higher. The teacher data is written as shown in FIG. 5A, and the envelope of the reproduction signal in this case is as shown in FIG. 5B due to the difference in the pit length. In the component analyzing means 33, the switch 36 is in the state shown in FIG. 4, and the upper envelope detecting means 37 and the lower envelope detecting means 38 output the upper and lower envelopes of the reproduced signal. The gate generation means receives the SYNC detection result shown in FIG. 5 (c) as an input and generates the sampling timing signal and the switching signal of the switch 39 shown in FIGS. 5 (d) and 5 (e) with a predetermined delay, and the sampling means 40 The upper envelope and the lower envelope are sampled respectively. The calculation means 42 subtracts both from the sampling result to obtain the envelope of the reproduction signal. By repeating this operation for each frame, a small value corresponding to the frequency component f1 and a large value corresponding to the frequency component f2 are alternately obtained, and the component analyzing means 33 further determines f1 and f2 from the sampling values. Is output to the control means as a frequency resolution signal. The control means 34 controls the high frequency characteristic of the transversal filter so that the output of the component analysis means 33 becomes a predetermined value.
Here, in the transversal filter, only the level characteristic changes and the phase characteristic does not change even when the coefficient changes,
The symmetric elements are controlled to be equal to each other around the center element of the coefficient vector. That is, the impulse response of the transversal filter is controlled so as to have a symmetrical waveform. As described above, the variation of the reproduction characteristics represented by the level components of f1 and f2 is adjusted so that the output of the waveform equalizer has a predetermined frequency resolution. Further, in the example of FIG. 3, the component analyzing means 33 takes the output of the waveform equalizing means as an input and adjusts the equalization characteristics so that it has a predetermined frequency resolution. It may provide a predetermined waveform equalization characteristic. In the above description, the frequency resolution of f1 and f2 is 2
This is an example of control by three components, but as can be easily understood, level control may be performed at a third frequency component f3 different from f1 and f2, and control by this may be performed. In waveform equalization using a transversal filter with a large number of taps, in the frequency characteristics, the frequency with high sensitivity to a specific element change of the coefficient vector is determined to some extent, so control with a larger number of frequency components requires a transformer with a larger number of taps. Effective for Versal filters.

Next, when the reproduction characteristic becomes asymmetric due to the shape variation of the front and rear ends of the pit or the tangential tilt, the phase characteristic of the transversal filter 14 is adjusted to compensate for this asymmetry. The need arises. FIG. 6 is an explanatory diagram of the operation for this case.

In FIG. 6, (a) shows a case where the pits of f2 are continuous, and FIG. 6 (b) shows the reproduction signal. However, when the reproduction characteristics are asymmetrical, this rise and The falling waveform becomes asymmetric. In the operation of the component analyzing means 33 for FIG. 6, first, the switch 36 is connected in the opposite direction to that shown in the figure, and the reproduced signal is differentiated to obtain the signal of FIG. 6 (c). FIG. 6 in which the upper peak of the obtained signal is detected
The lower peak envelope of FIG. 6E obtained by detecting the upper peak envelope and the lower peak of (d) is obtained. The upper peak envelope and the lower peak envelope are sampled in the same manner as in FIG. 4, and the ratio thereof is output as a phase resolution signal. The control means 34 controls the coefficient of the transversal filter so that the phase resolution signal has a predetermined value. At this time, the coefficient vector of the transversal filter is controlled so as to be asymmetrical about the center coefficient, and this is performed by gradually changing the coefficients on both sides of the center coefficient in the opposite direction.

The operation of FIG. 5 described above adjusts the level characteristic of the equalizing means and the operation of FIG. 6 adjusts the phase characteristic of the equalizing means. However, it is easily understood that both can be operated simultaneously. It is possible to change the symmetric element of the coefficient vector by the same rate in the control of the level characteristic, and to change the symmetric element of the coefficient vector in the opposite direction stepwise in the control of the phase characteristic.

As described above, since the accurate teacher data pattern is defined, accurate learning of the equalizing means can be performed. By fixing the equalization characteristic thus obtained and reproducing the program area, high quality data reproduction can be performed.

The optical disc medium 1 is clamped in the optical disc device by using the center hole at the innermost periphery, and the disc diameter made of plastic is relatively large as 120 mm. Therefore, the tilt amount mainly changes at the inner peripheral portion and the outer peripheral portion. there's a possibility that. In this case, it is desirable to change the compensation characteristic over the entire circumference of the disc along with the change in tilt amount. In the above-mentioned operation, the learning result in the inner peripheral portion is held in the learning means, and subsequently, learning is performed in the learning region 32 in the outer peripheral portion to obtain the compensation characteristic of the outer peripheral portion, and the inner peripheral portion and the outer peripheral portion are obtained. It is possible to set the compensation characteristics in all regions by interpolating the compensation characteristics in. Similarly, in setting the equalization characteristics by the learning area, it is necessary to average the results over one round of the recording track, and in order to guarantee the measurement over one round of the track, if there are many frequency components set, multiple tracks are set. It is effective to set the teacher data over.

The optical disk medium may be a rewritable type instead of a read-only type. In this case, a predetermined pattern may be recorded in the learning area, and this may be reproduced to perform learning.

[0030]

As described above, according to the present invention, by providing a learning area recorded so as to be in a predetermined state and reproducing the same, the characteristics of the equalizing means are adjusted, thereby reproducing the data with high reliability. The present invention provides an excellent optical disk device and optical disk medium that realizes an automatic adjustment function for compensating a change in disk reproduction characteristics caused by an optical disk medium, an optical disk device, and a combination of both.

In particular, since it is controlled by the ratio of frequency components, it is unlikely to be affected by dropout or the like. Further, when the equalization characteristic is set from the jitter of the random signal, the influence of dropout is not likely to occur.

Further, the result of the inner peripheral portion and the result of the outer peripheral portion can be interpolated and applied to the entire area.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical disc medium according to an embodiment of the present invention.

FIG. 2 is a detailed view of an optical disc medium according to an embodiment of the present invention.

FIG. 3 is a block diagram of an essential part of an optical disk device of the present invention.

FIG. 4 is a block diagram of an essential part of FIG.

FIG. 5 is a diagram illustrating a first teacher data pattern and operation.

FIG. 6 is a diagram illustrating a second teacher data pattern and operation.

FIG. 7 is a block diagram of a conventional optical disc medium.

FIG. 8 is a block diagram of an optical disk device.

FIG. 9 is a block diagram of a binarizing unit of the optical disc device.

[Explanation of symbols]

 1 optical disk medium 2 data area 3 pit 4 recording track 5 semiconductor laser, LD 6 optical system 7 light spot 8 pin photodiode, PD 9 preamplifier 10 binarization means 11 SYNC detection means 12 demodulation means 13 error correction means, ECC 14 transformer Versal filter 15 Comparison means 16 Subtraction means 17 Learning means 18 Phase synchronization circuit, PLL 19 Judging means 31, 32 Learning area 33 Component analysis means 34 Control means 35 Differentiation means 36, 39 Switch 37 Upper envelope detection means 38 Lower envelope detection means 40 Sampling Means 41 Gate Generating Means 42 Arithmetic Means

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shunji Ohara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (12)

[Claims] 1. Optical means for reproducing information on an optical disk medium having a learning area in which predetermined data is recorded,
Amplifying means for converting reproduction information of the optical system into an electric signal and outputting as a reproduction signal, equalization means for equalizing waveforms of the reproduction signal by controlling equalization characteristics by a control signal, and output signal of the equalization means. Determining means for binarizing and outputting read data, component analyzing means for analyzing the frequency component of the reproduction signal or output signal of the equalizing means and outputting a frequency resolution signal, and predetermined conversion to the frequency resolution signal. An optical disk device comprising: 2. The component analysis means analyzes the frequency component of the output signal of the equalization means, and the control means outputs the control signal so that the frequency resolution signal has a predetermined value. Optical disk device. 3. The component analyzing means analyzes the level of the frequency component output from the equalizing means and outputs a frequency resolution signal, and the equalizing means adjusts the level characteristic by this. 2. The optical disk device described in 2. 4. The component analyzing means analyzes the level and phase of the frequency component output from the equalizing means and outputs a frequency resolution signal,
3. The optical disk device according to claim 1, wherein the control means controls the level characteristic and the phase characteristic of the equalizing means by this. 5. The equalization means is composed of an N tap transversal filter, and the control means outputs the coefficient vector of the transversal filter by a predetermined conversion from the level signal and the phase signal. Optical disk device. 6. An optical disk medium, wherein a learning area is composed of at least three or more tracks, and a learning operation is realized with a predetermined three tracks as one unit. 7. A learning pattern having fundamental frequency components f1 and f2 is recorded on at least one track, and f
7. The optical disk medium according to claim 6, wherein 1 is a frequency corresponding to the continuation of the shortest mark space, and f2 is a frequency corresponding to the succession of the mark space larger than the light spot diameter. 8. A learning pattern having a fundamental frequency component f2 is recorded on at least one track, and f2 is a frequency corresponding to a continuous mark space larger than the light spot diameter. Optical disc media. 9. The optical disk medium according to claim 6, wherein different fundamental frequency components f1, f2 and f3 are recorded on predetermined three tracks. 10. The optical disk medium according to claim 7 or 9, wherein the component analyzing means analyzes the magnitude of the frequency component of f1, f2 or f3 of the reproduced signal, and the ratio of the f1, f2 components or the f3, f2 component. 3. The optical disk device according to claim 1, wherein a frequency resolution signal is output as a ratio of the above, and the control means controls the equalization characteristic so that the frequency resolution signal has a predetermined value. 11. The optical disk medium according to claim 6, wherein the learning area is provided in each of the inner peripheral portion and the outer peripheral portion. 12. The optical disk medium according to claim 11, wherein the control means stores the equalization characteristic result obtained by reproducing the inner peripheral learning area and the result from the outer peripheral learning area, and both learnings are stored. 3. The optical disk device according to claim 1, wherein the characteristics of the equalizing means are controlled by interpolating the results of both when reproducing the data area sandwiched between the areas.