JP2002150690A - Optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device which can perform stable adaptive operation without especially providing an area for a training sequence. SOLUTION: The rewritable optical disk device is provided with a data discrimination part 6 including an adaptive operation circuit which uses a signal caused by unrewritable information for clock generation, which is so recorded in an emboss system that it may be detected at intervals of a certain time, to dynamically change a tap coefficient and a criterion for discrimination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical disk device having a data determination unit for performing an adaptive operation.

[0002]

2. Description of the Related Art In recent years, the density of optical disks has been increased, and attempts have been made to improve track density and recording linear density.
When increasing the track density, there is a problem in that an allowable amount of a tracking error is reduced by narrowing the track pitch. However, the generally used push-pull tracking method is weak against phenomena that cause asymmetry in the optical system such as tilt of the optical disk and optical axis deviation, and when such a phenomenon occurs, the tracking control system is relatively large. Has a steady state deviation. A sample servo tracking method is known as a tracking control method that is strong against asymmetry of the optical system. In the sample servo tracking method, a data area in which information is recorded on a track and a preformatted servo area are alternately arranged, and a reproduction R from the servo area is recorded.
This is a method for performing tracking control using the F signal.

FIG. 11 is a servo area diagram showing an example of a servo area of an optical disk employing the sample servo tracking method. As shown in FIG. 11, a clock pit 91 is arranged on the track center line in the servo area. The first clock pit 91 is located at a certain distance from the clock pit 91 along the track and at a predetermined distance from the track center line. Wobble pit 92, first wobble pit 92
A second wobble pit 93 is provided at a position away from the track center line by a predetermined distance in a direction opposite to the first wobble pit, with a certain distance from the track along the track.

FIG. 12 is a timing chart showing a reproduced RF signal in the servo area shown in FIG. In FIG.
The section Tc is a clock pit, the section Tw1 is a first wobble pit, and the section Tw2 is a second wobble pit reproduced signal. For detecting a tracking error signal, a reproduced RF signal from a pair of wobble pits 92 and 93 is used. This will be described with reference to FIG.

FIGS. 13A to 13C are timing charts showing the principle of tracking error detection using the servo area shown in FIG. As shown in FIG. 11, the wobble pits 92 and 93 are displaced in the opposite directions by the same distance from the track center line. Therefore, when the beam for reproducing the servo area passes on the track center line, As shown in FIG. 13A, the reduced amount Va1 of the reflected light obtained from the first wobble pit 92 is equal to the reduced amount Va2 of the reflected light obtained from the second wobble pit 93.
When the beam passing position is shifted to the first wobble pit 92 side, as shown in FIG. 13B, the reduction amount Vb1 of the amount of light reflected by the first wobble pit 92 increases,
Reduction amount Vb of reflected light amount by second wobble pit 93
2 becomes smaller.

Conversely, when the beam passing position is shifted toward the second wobble pit 93, as shown in FIG.
Reduction amount Vc of reflected light amount by first wobble pit 92
1 is reduced, and the amount of decrease Vc2 in the amount of light reflected by the second wobble pit 93 is increased.
Of the reproduction section Tw1 of the wobble pit 92 and the second point
Of the wobble pit 93 is used as a tracking error signal.

As described above, in the sample servo tracking method, since all reflected light from the optical disk is used, the sample servo tracking method is less susceptible to lens shift, optical disk tilt, and the like, and has less steady-state deviation in tracking control than the push-pull tracking method. Become. Clock pits 91 are provided in the servo area shown in FIG. In the sample servo tracking method, a clock is generally reproduced using such a clock pit. Normally, clock reproduction is performed at the same time as data recording, by using a VFO (Variable Frequency Osc) for clock reproduction.
illator) and reading this VFO. In the case of the sample servo tracking method,
When the clock is reproduced by such a method, the wobble pit cannot be detected stably with respect to the fluctuation of the rotation of the optical disk, which causes an unstable factor of the tracking control.

On the other hand, in order to improve the recording linear density, a recording mark smaller than a reproduction spot has been used. However, a reduction in the reproduction signal level and an increase in inter-symbol interference due to an adjacent mark have been problematic. Has become. As a data decision method that addresses this problem, the partial response maximum likelihood estimation method (Partial Response Maximum ikelihood, P
RML method) has been used. In the partial response maximum likelihood estimation method, a reproduction system including an equalizer is partially equalized by an equalizer so as to match a reproduction characteristic assumed by a data determiner in a subsequent stage, and a convolutional code of a convolutional code is used as a data determiner. The recording data is determined using a maximum likelihood estimator represented by a Viterbi decoder designed as a decoding means. Furthermore, in order to cope with fluctuations in the characteristics of the reproduction system, many optical disk devices having an adaptive data determination unit that dynamically changes the operation parameters of the equalizer and the maximum likelihood estimator based on a specific calculation method have been devised. ing. A summary of the configuration of such an adaptive data determination unit includes, for example, (SUHQureshi,
“Adaptive Equalization”, Proc.IEEE, vol.73, pp.1349
-1387, Sep. 1985).

FIG. 10 is a block diagram showing a conventional optical disk device, showing a case where a conventional adaptive data determination unit is provided. 10, reference numeral 71 denotes a recording medium such as an MO,
72 is an optical detection system that detects light from the recording medium, 73 is an equalizer that performs partial equalization, 74 is a tap coefficient controller that adjusts the tap coefficient of the equalizer 73, and 75 is a data determination result described later. The passing feedback filter 76 is a maximum likelihood estimator that estimates recording data.

The operation of the optical disk device configured as described above will be described. Optical disk devices are generally modeled as baseband transmission paths. Assuming that the recorded data sequence is {x (k)} and the impulse response of the recording / reproducing system is {h (k)}, the signal 81 read from the recording medium 71 by the optical detection system 72 is a convolution sum. Is expressed as y (n) = (h * x) (n) using the symbol * indicating The signal 81 has an impulse response {c (k)}
Is partially equalized so as to have a PR (1, 2, 1) characteristic. That is, the partially equalized signal 82, which is the output signal of the equalizer 73, is represented by z (n) = (c
* H * x) (n), and the tap coefficient controller 74 calculates g (n) = (c * h) by a method described later.
(N) = 1 (n = -1, 1), g (n) = 2 (n =
0) and g (n) = 0 (others) so that the equalizer 7
The tap coefficient {c (n)} of No. 3 is adjusted. The partially equalized signal 82 is input to the maximum likelihood estimator 76, and the maximum likelihood estimator 76 estimates recording data according to the assumed reproduction characteristic g (n). Tap coefficient ｛c of equalizer 73
(N) The adjustment of｝ is performed as follows.

The data judgment result 83 passes through a feedback filter 75 having {g (n)} as an impulse response.
Difference signal {e (k)} between feedback filter output and equalizer output
Is input to the tap coefficient controller 74 as an equalization error signal 84. Based on this signal, the tap controller 74 sequentially adjusts the tap coefficients of the equalizer 73 by a well-known decision feedback algorithm.

That is, n of the equalizer 73 at time k
When the th coefficient is represented by c (k, n), c (k + 1, n) = c (k, n) + μ × y (kn) ×
e (k). However, in the above equation, the maximum likelihood estimator 7
The delay of the judgment by No. 6 must be further considered.

However, the adaptive operation based on the signal from the area in which the rewritable information is recorded has a difficulty in the adaptive operation due to the decrease in the reproduced signal amplitude and the increase in the noise component accompanying the increase in the storage capacity. Become.

There is also a method of providing a training sequence for an adaptive operation in a dedicated area separately from the rewritable information. In this case, the parameters of the equalizer are adjusted by reproducing a known data sequence recorded on the optical disk in advance. Assuming that the known data string is {x (k)} and the impulse response of the recording / reproducing system is {h (k)}, {x (k)}
(K)｝ is reproduced as follows.

Y (n) = (h * x) (n) The signal {z (n)} that has passed through the equalizer is represented by z (n) = (c * y) (n). When the equalizer equalizes the recording / reproducing characteristic c * h including the equalizer to PR (1, 2, 1), that is, the same characteristic as the above-mentioned g, g * x = c * y holds. Here, since g, x, and y are known, it is possible to determine c using, for example, the least squares method.

As described above, when a training sequence is provided, there is a problem that storage capacity is reduced by providing a dedicated training sequence. The optical disk device described in Japanese Patent Application Laid-Open No. 8-194906 uses a recording medium in which two types of frames, a servo frame in which optical disk control information is written in advance and a data frame for information recording, are arranged. Using the fact that the servo frame has a lower appearance frequency than the data frame and providing a training sequence to be used for the adaptive operation of the adaptive equalizer in the servo frame, the decrease in storage capacity due to recording of the training sequence is reduced. It is devised to do.

[0017]

However, in fields where higher densities are always required, such as optical disc devices, even if the above-described improvements are made,
It is not enough in that the capacity of the optical disc is compressed using a special training sequence. This optical disc device is required to realize high density by having an adaptive data determination unit that performs a stable adaptive operation without particularly providing a training sequence area.

An object of the present invention is to provide an optical disk apparatus capable of performing a stable adaptive operation without providing a region for a training sequence in order to satisfy this demand.

[0019]

In order to solve the above-mentioned problems, an optical disk apparatus according to the present invention is a rewritable optical disk apparatus, which generates a clock signal recorded by an emboss method so as to be detected at predetermined time intervals. A data determination unit including an adaptive operation circuit for dynamically changing a tap coefficient and a determination criterion using a signal resulting from non-rewritable information for use.

Thus, it is possible to obtain an optical disk apparatus capable of performing a stable adaptive operation without providing a training sequence area.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk device according to a first aspect of the present invention is a rewritable optical disk device,
A data determination unit including an adaptive operation circuit that dynamically changes tap coefficients and determination criteria using a signal caused by non-rewritable information for clock generation recorded in an embossed manner so as to be detected at a fixed time interval. Is to be provided. This configuration has an effect of performing an adaptive operation using a signal having a high signal-to-noise ratio.

According to a second aspect of the present invention, in the optical disk device of the first aspect, the adaptive operation circuit is an equalizer using a transversal filter. With this configuration, the equalizer has an effect of coping with fluctuations in the reproduction characteristics.

According to a third aspect of the present invention, in the optical disk device of the first aspect, the adaptive operation circuit is a maximum likelihood estimator. With this configuration, the determination criterion of the maximum likelihood estimator is dynamically updated to cope with fluctuations in the reproduction characteristics.

According to a fourth aspect of the present invention, in the optical disk device of the first aspect, the adaptive operation circuit is an equalizer using a transversal filter and a maximum likelihood estimator. With this configuration, the adaptive operation by the equalizer and the update of the criterion of the maximum likelihood estimator are performed at the same time, thereby reducing the amount of noise amplification and the equalization error by the equalizer.

An optical disk device according to a fifth aspect of the present invention is the optical disk device according to the second aspect, wherein a maximum likelihood estimator is provided after the equalizer. This configuration has the effect of reducing the amount of noise amplification and the equalization error by the equalizer and fixing the criterion of the maximum likelihood estimator, thereby avoiding circuit complexity.

According to a sixth aspect of the present invention, in the optical disk device of the third aspect, a tap coefficient fixed type equalizer is provided at a stage preceding the maximum likelihood estimator. With this configuration, it is possible to use a fixed-coefficient equalizer and limit the increase in the internal state of the maximum likelihood estimator (restrict the candidates of signal sequences to be reliably held), thereby avoiding circuit complexity. Has an action.

An optical disk apparatus according to a seventh aspect of the present invention is a rewritable optical disk apparatus, wherein a signal originating from non-rewritable information and an rewritable information recorded in an embossed manner are detected at predetermined time intervals. A data determination unit including an adaptive operation circuit for dynamically changing a tap coefficient and a determination criterion using a signal resulting from the determination is provided. With this configuration, there is an effect that the adaptive operation is performed in consideration of the characteristic fluctuation at the time of reproducing the rewritable information.

According to an eighth aspect of the present invention, in the optical disk device of the seventh aspect, the adaptive operation circuit is an equalizer using a transversal filter. With this configuration, the equalizer has the effect of compensating for all variations in reproduction characteristics.

According to a ninth aspect of the present invention, in the optical disk device of the seventh aspect, the adaptive operation circuit is a maximum likelihood estimator. With this configuration, by dynamically changing the criterion of the maximum likelihood estimator,
It has the effect of compensating for all variations in reproduction characteristics.

According to a tenth aspect of the present invention, in the optical disk device of the seventh aspect, the adaptive operation circuit is an equalizer using a transversal filter and a maximum likelihood estimator. This configuration has the effect of dynamically changing the tap coefficient of the equalizer and the criterion of the maximum likelihood estimator, thereby compensating for all variations in reproduction characteristics.

According to an eleventh aspect of the present invention, in the optical disk device according to the seventh aspect, the adaptive operation circuit is based on the non-rewritable information recorded by the emboss method so as to be detected at a constant time interval. A maximum likelihood estimator that dynamically changes tap coefficients and determination criteria using a signal report, and an equalizer that dynamically changes tap coefficients and determination criteria using a signal resulting from rewritable information. It was decided to have. With this configuration, the maximum likelihood estimator has an effect of coping with a characteristic variation during a period when the adaptive operation is not performed and reducing an equalization error.

According to a twelfth aspect of the present invention, in the optical disk device of the seventh aspect, the adaptive operation circuit is based on the non-rewritable information recorded by the emboss method so as to be detected at a constant time interval. An equalizer that dynamically changes tap coefficients and determination criteria using a signal report, and a maximum likelihood estimator that dynamically changes tap coefficients and determination criteria using a signal resulting from rewritable information. It was decided to have. With this configuration, it is possible to cope with characteristic fluctuations during a period when the equalizer does not perform an adaptive operation, and to reduce the probability of erroneous determination.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a block diagram showing an optical disk apparatus according to Embodiment 1 of the present invention.
1 shows a sample servo type magneto-optical disk reproducing device. In FIG. 1, 1 is a recording medium such as an MO, 2 is an optical detection system that detects light from the recording medium, 2 is a clock generation unit that generates a clock, 4 is an address decoding unit that decodes address data, and 5 is a tracking unit. A tracking control unit for performing control; 6 a data determination unit including an adaptive operation circuit;
7, 8 are low-pass filters for passing the low-frequency portion of the signal, 9 is an automatic amplitude adjustment circuit for automatically adjusting the amplitude, 1
Reference numerals 0 and 11 are sampling circuits for sampling signals.

FIG. 9 is a format diagram showing the format structure of a recording medium. As shown in FIG. 9, in each recording unit of the recording medium, a servo area 51 in which information is recorded by an embossing method at the time of manufacturing and a rewritable data area 52 that can be used freely by a user are set. In the servo area 51, a clock generation mark, a tracking signal generation mark, and address information are recorded by embossing when an optical disc is manufactured. The interval between the clock generation mark and the adjacent tracking signal generation mark is set wide enough so that mutual interference does not occur. Data area 5
2, the user can record information by a magneto-optical recording method. Reading of recorded information is performed by irradiating the recording medium 1 with light using the optical detection system 2 and analyzing reflected light from the recording medium 1.

In the case of a magneto-optical disk of the sample servo system, drive control information recorded by the emboss system is detected as a reflected light amount signal 21, and information written by a user is detected as a magneto-optical signal 22. After noise is removed from the reflected light amount signal 21 by the low-pass filter 7, the amplitude is normalized by the automatic amplitude control device 9, and is input to the clock generator 3 and the sampling circuit 10. The clock generation unit 3 detects a fluctuation in the light amount of the normalized reflected light amount signal 24 caused by the clock generation mark input at a constant time interval t, and detects a frequency of an integral multiple of 1 / t. A clock 26 having the following is generated and provided to each unit of the device. Further, the normalized reflected light amount signal 24 is sampled in the sampling circuit 10 at the cycle of the clock 26, and is input to the address information decoding unit 4, the tracking control unit 5, and the data determination unit 6.

On the other hand, the magneto-optical signal 22 detected by the optical detection system 2 is subjected to noise removal using a low-pass filter 8 having the same characteristics as the low-pass filter 7 for the reflected light amount signal. The data is sampled by the sampling circuit 11 and input to the data determination unit 6.

FIG. 2 is a block diagram showing the data judgment unit 6 of FIG. In FIG. 2, reference numeral 101 denotes an impulse response estimating unit for estimating an impulse response of a reproduction system; 102, an inter-symbol interference amount estimating filter for estimating an inter-symbol interference amount; It is a tap coefficient controller for setting tap coefficients of the intersymbol interference estimation filter 102.

The operation of the data judging section 6 thus configured will be described. In this embodiment, a time zone in which the reflected light amount signal 21 is significant and a time zone in which the magneto-optical signal 22 is significant are completely separated. The operation of the data determination unit 6 during the time period in which the reflected light signal 21 is significant is as follows. The impulse response estimating unit 101 in FIG. 2 extracts a fluctuation component caused by the clock generation mark by applying a window having a certain time width to the sampled reflected light amount signal 27, and extracts the clock generation mark. The impulse response of the reproducing system is estimated based on the known information about the length of the reproduction system. The tap coefficient controller 103 sets tap coefficients of the intersymbol interference amount estimation filter 102 configured by a transversal filter based on the impulse response estimation result.

In the time zone where the magneto-optical signal 22 is significant, the following operation is performed while the tap coefficient of the intersymbol interference amount estimation filter 102 is fixed. The intersymbol interference estimation filter 102 receives the input signal from the binary decision unit 103 and estimates the intersymbol interference. The sampled magneto-optical signal 28 is used as an inter-symbol interference amount estimation filter 1
By subtracting from the output signal of No. 02, the intersymbol interference component is removed. The magneto-optical signal 111 from which the intersymbol interference component has been removed is input to the binary decision unit 103,
The binary determiner 103 performs a binary determination and outputs the determined recording data sequence 29.

As described above, by using the clock generation mark provided on the optical disk of the sample servo system, a decrease in storage capacity caused by providing a special area for a training sequence for impulse response estimation can be avoided. be able to. Further, as described above, when the density of the recording medium 1 is increased, the signal amplitude of the magneto-optical signal 22 including the information recorded by the user tends to decrease, while the drive control including the clock generation mark is performed. Since the reflected light amount signal 21 including information has a sufficient signal amplitude due to performance restrictions, the adaptive operation is performed using the reflected light amount signal 21 to estimate the impulse response and remove the intersymbol interference component. It can be performed reliably.

(Embodiment 2) FIG. 3 is a block diagram showing a data judging unit 6 of a sample servo type magneto-optical disc reproducing apparatus constituting an optical disc apparatus according to Embodiment 2 of the present invention. 3, reference numeral 401 denotes a reproduction characteristic estimator for estimating a transfer function of a reproduction system; 402, a tap coefficient controller for setting tap coefficients of an equalizer 404 described later;
3 is a criterion controller for setting a criterion, 404 is an equalizer for performing partial equalization of the sampled magneto-optical signal 28, 40
Reference numeral 5 denotes a maximum likelihood estimator for estimating the recording data sequence 29 from the partially equalized magneto-optical signal 411.

The operation of the data judging section 6 thus configured will be described. In a time zone in which the reflected light amount signal 21 is significant, the reproduction characteristic estimator 401 extracts a fluctuation portion caused by the clock generation mark from the sampled reflected light amount signal 27 and obtains known information on the length of the clock generation mark. Is used to estimate the transfer function of the regeneration system. The reproduction characteristic estimator 401 represents the transfer function of the reproduction system as a rational function, and the coefficient of the denominator polynomial is represented by the tap coefficient controller 4.
02, becomes a tap coefficient of an equalizer 404 constituted by a transversal filter, and a coefficient of a numerator polynomial is passed to a criterion controller 403, and the maximum likelihood estimator 405
Is used to set the criterion.

In the time zone where the magneto-optical signal 22 is significant, the following operation is performed while the tap coefficient of the equalizer 404 and the criterion of the maximum likelihood estimator 405 are fixed. Equalizer 404
Performs partial equalization of the sampled magneto-optical signal 28 according to the tap coefficient controller 402 and outputs the result to the maximum likelihood estimator 405. The maximum likelihood estimator 405 estimates the recording data sequence 29 from the partially equalized magneto-optical signal 411 according to the criterion controller 403.

As described above, in the present embodiment, for the same reason as in the first embodiment, by using the clock generation mark provided on the optical disk of the sample servo system,
By avoiding a reduction in storage capacity caused by providing a special area for a training sequence for estimating reproduction characteristics, and performing an adaptive operation using the reflected light amount signal 21, the tap coefficient and the determination criterion of the equalizer 404 are determined. Can be set reliably.

(Embodiment 3) FIG. 4 is a block diagram showing a data judging section 6 of a sample servo type magneto-optical disc reproducing apparatus constituting an optical disc apparatus according to Embodiment 3 of the present invention. In FIG. 4, reference numeral 501 denotes a tap coefficient controller for setting tap coefficients of an equalizer 502 described later;
Reference numeral 2 denotes an equalizer that performs partial equalization of the sampled magneto-optical signal 28, and reference numeral 503 denotes a maximum likelihood estimator that estimates a recording data sequence from the partially equalized magneto-optical signal 511.

The operation of the data judging unit 6 thus configured will be described. In a time zone in which the reflected light amount signal 21 is significant, the tap coefficient controller 501 extracts a fluctuation portion due to the clock generation mark from the sampled reflected light amount signal 27 and obtains a known value related to the length of the clock generation mark. Based on the information, the tap coefficients of the equalizer 502 are adjusted so that the impulse response of the reproduction system including the equalizer 502 constituted by the transversal filter matches the impulse response assumed by the maximum likelihood estimator 503 at the subsequent stage. Set.

In the time zone where the magneto-optical signal 22 is significant, the following operation is performed while the tap coefficient of the equalizer 502 is fixed. The equalizer 502 performs partial equalization of the sampled magneto-optical signal 28, and outputs the result to the maximum likelihood estimator 503. The maximum likelihood estimator 503 estimates the recording data sequence 29 from the partially equalized magneto-optical signal 511 based on the impulse response of the reproduction characteristic assumed in advance using the Viterbi algorithm.

As described above, in the present embodiment, for the same reason as in the first embodiment, by using the clock generation mark provided on the optical disk of the sample servo system,
Setting the tap coefficient of the equalizer 502 by avoiding a reduction in storage capacity caused by providing a special area for the training sequence for the equalizer 502 and performing an adaptive operation using the reflected light amount signal 21 Can be performed reliably.

(Embodiment 4) FIG. 5 is a block diagram showing a data judging section 6 of a sample servo type magneto-optical disk reproducing apparatus constituting an optical disk apparatus according to Embodiment 4 of the present invention. In FIG. 5, reference numeral 601 denotes an impulse response estimator for estimating an impulse response of a reproduction system including an equalizer 603 to be described later; 602, a criterion controller for setting a criterion for determination; 603, a sampled magneto-optical signal 28; 604 is a partial-equalized magneto-optical signal 6
This is a maximum likelihood estimator for estimating a recording data sequence from 11.

The operation of the data judging section 6 thus configured will be described. In a time zone in which the reflected light signal 21 is significant, the following operation is performed. The impulse response estimator 601 extracts a fluctuation portion caused by the clock generation mark from the sampled reflected light amount signal 27, and also obtains known information regarding the length of the clock generation mark and the tap coefficient of the equalizer 603. Then, the impulse response of the reproduction system including the equalizer 603 is estimated, and the result is output to the criterion controller 602. The criterion controller 602 sets the criterion of the maximum likelihood estimator 604 according to the output of the impulse response estimator 601.

In the time zone where the magneto-optical signal 22 is significant, the following operation is performed while the criterion of the maximum likelihood estimator 604 is fixed. Equalizer 60 composed of a transversal filter
Numeral 3 partially equalizes the magneto-optical signal sampled so that the reproducing system has an impulse response assumed at the time of design. The maximum likelihood estimator 604 estimates the recording data sequence 29 from the partially equalized magneto-optical signal 611 using the Viterbi algorithm.

As described above, in the present embodiment, for the same reason as in the first embodiment, by using the clock generation mark provided on the optical disk of the sample servo system,
By avoiding a decrease in storage capacity caused by providing a special region for a training sequence for impulse response estimation, and performing an adaptive operation using the reflected light amount signal 21,
It is possible to reliably set the criterion.

(Embodiment 5) FIG. 6 is a block diagram showing a data judging section 6 of a sample servo type magneto-optical disk reproducing apparatus constituting an optical disk apparatus according to Embodiment 5 of the present invention. 6, reference numeral 701 denotes an impulse response estimator for estimating an impulse response; 702, a tap coefficient controller for setting tap coefficients of an inter-symbol interference amount estimation filter 705, which will be described later; An updating tap coefficient controller 704; an equalizer 704 for partially equalizing the sampled magneto-optical signal 28;
Is an inter-symbol interference estimation filter for estimating the inter-symbol interference, and 706 is a maximum likelihood estimator for estimating the recording data sequence 29 from the partially equalized magneto-optical signal 711.

The operation of the data discriminating section 6 thus configured will be described. In the present embodiment, the adjusting operation based on the reflected light amount and the adjusting operation based on the magneto-optical signal are included. However, in the optical disk of the sample servo method, the region where the reflected light amount signal has an effective component and the magneto-optical signal has an effective component Since the regions are separated, the two adjustment operations are not performed simultaneously.

In a time zone in which the reflected light signal 21 is significant, the following operation is performed while the tap coefficient of the equalizer 704 constituted by a transversal filter is fixed. The impulse response estimator 701 calculates the sampled reflected light signal 2
7, a fluctuation portion caused by the clock generation mark is extracted, an impulse response is estimated based on known information on the length of the clock generation mark, and the estimation result is output to the tap coefficient controller 702. The tap coefficient controller 702
Based on the impulse response estimation result, a tap coefficient of the intersymbol interference amount estimation filter 705 is set.

In the time zone where the magneto-optical signal 22 is significant, the reproduction of the sampled magneto-optical signal 28 and the adaptive operation of the equalizer 704 are performed next while the tap coefficients of the intersymbol interference estimation filter 705 are fixed. It is performed as follows. After passing through the equalizer 704, the sampled magneto-optical signal 28 is input to the binary decision unit 706 after removing the estimated amount of the inter-symbol interference component. The recorded data sequence 29 determined by the binary determiner 706 is used as an intersymbol interference amount estimation filter 705.
Will be returned to The tap coefficient controller 703 uses the difference signal between the determined recording data sequence 29 and the magneto-optical signal 28 from which the inter-symbol interference has been removed as an error signal, and
The tap coefficient of 4 is updated. Updating of the tap coefficient of the equalizer 704 is always performed while a region where magneto-optical recording is being performed is being reproduced.

As described above, in the present embodiment, for the same reason as in the first embodiment, by using the clock generation mark provided on the optical disk of the sample servo system,
By avoiding a decrease in storage capacity caused by providing a special region for a training sequence for impulse response estimation, and performing an adaptive operation using the reflected light amount signal 21,
It is possible to reliably set the tap coefficient of the intersymbol interference amount estimation filter 705. Also, the magneto-optical signal 2
By controlling the tap coefficients of the equalizer 704 using 2, it is possible to perform a finer adaptive operation.

(Embodiment 6) FIG. 7 is a block diagram showing a data judging section 6 of a sample servo type magneto-optical disk reproducing apparatus constituting an optical disk apparatus according to Embodiment 6 of the present invention. 7, reference numeral 801 denotes an impulse response estimator for estimating an impulse response; 802, a tap coefficient controller for setting a tap coefficient of a feedback filter 805, which will be described later; 803, a determination reference controller for setting a determination criterion;
Reference numeral 804 denotes a tap coefficient controller for updating a tap coefficient of an equalizer 806 described later, reference numeral 805 denotes a feedback filter to which a recording data sequence 29 is input, and reference numeral 806 denotes a sampled magneto-optical signal 28.
807 is a maximum likelihood estimator that estimates the recording data sequence 29 from the partially equalized magneto-optical signal 811.

The operation of the data discriminating section 6 configured as described above will be described. As in the fifth embodiment, the present embodiment also includes an adjustment operation based on the reflected light amount and an adjustment operation based on the magneto-optical signal. Since the region where the magnetic signal has the effective component is separated, these two adjustment operations are not performed simultaneously.

In the time zone where the reflected light amount signal 21 is significant, the following operation is performed while the tap coefficient of the equalizer 806 formed by the transversal filter is fixed. The impulse response estimator 801 calculates the sampled reflected light amount signal 2
7, a fluctuation portion caused by the clock generation mark is extracted, an impulse response of the reproduction system is estimated based on known information on the length of the clock generation mark, and the result is determined by the tap coefficient controller 802 and the criterion. Output to the controller 803. The tap coefficient controller 802 includes a feedback filter 805
Set the tap coefficient of. The criterion controller 803 sets a criterion for the maximum likelihood estimator 807.

In the time zone where the magneto-optical signal 22 is significant, the following operation is performed while the tap coefficients of the feedback filter 805 and the criterion of the maximum likelihood estimator 807 are fixed. The equalizer 806 performs an adaptive operation according to a decision feedback algorithm. That is, the tap coefficient controller 804 performs reproduction of the partially equalized magneto-optical signal 811 and feedback filter 805.
The difference from the output signal of the
The tap coefficient of 6 is set. The magneto-optical signal 811 partially equalized by the equalizer 806 is input to the maximum likelihood estimator 807, and the recording data sequence 29 is determined. The determined recording data sequence 29 is output to the outside and input to the feedback filter 805 to be used for controlling the tap coefficient of the equalizer 806.

As described above, in the present embodiment, for the same reason as in the first embodiment, by using the clock generation mark provided on the optical disk of the sample servo system,
By avoiding a decrease in storage capacity caused by providing a special region for a training sequence for impulse response estimation, and performing an adaptive operation using the reflected light amount signal 21,
Tap coefficient of feedback filter 805 and maximum likelihood estimator 80
7 can be set reliably. Further, by controlling the tap coefficient of the equalizer 806 using the magneto-optical signal 22, a finer adaptive operation can be performed.

(Embodiment 7) FIG. 8 is a block diagram showing a data judging section 6 of a sample servo type magneto-optical disk reproducing apparatus constituting an optical disk apparatus according to Embodiment 7 of the present invention. 8, reference numeral 901 denotes a reproduction characteristic estimator for estimating a transfer function of a reproduction system; 902, a tap coefficient controller for setting tap coefficients of an equalizer 904 described later;
3 is a criterion controller for setting a criterion for determination, 904 is an equalizer for partially equalizing the sampled magneto-optical signal 28, 90
Reference numeral 5 denotes a maximum likelihood estimator that estimates the recording data sequence 29 from the partially equalized magneto-optical signal 911.

The operation of the data discriminating section 6 configured as described above will be described. As in the fifth embodiment, the present embodiment also includes an adjustment operation based on the reflected light amount and an adjustment operation based on the magneto-optical signal. Since the region where the magnetic signal has the effective component is separated, these two adjustment operations are not performed simultaneously.

The following operation is performed in a time zone in which the reflected light signal 21 is significant. The reproduction characteristic estimator 901 extracts a fluctuation portion caused by the clock generation mark from the sampled reflected light amount signal 27 and calculates a transfer function of the reproduction system based on known information on the length of the clock generation mark. presume. The transfer function of the reproduction system is expressed as a rational function, and the coefficients of the denominator polynomial are passed to the tap coefficient controller 902,
The tap coefficients of the equalizer 904 constituted by a transversal filter are used, and the coefficients of the numerator polynomial are passed to the criterion controller 903 and used for the criterion setting of the maximum likelihood estimator 905.

In the time zone where the magneto-optical signal 22 is significant, the following operation is performed while the tap coefficient of the equalizer 904 is fixed. The equalizer 904 performs partial equalization of the sampled magneto-optical signal 28 according to the tap coefficient controller 902, and outputs the result to the maximum likelihood estimator 905. The maximum likelihood estimator 905 outputs the partially equalized magneto-optical signal 9 according to the criterion controller 903.
From 11, the recording data sequence 29 is estimated. During reproduction of the magneto-optical signal, the criterion controller 903 performs a parameter estimation of a linear system in which the determined recording data sequence 29 is input and the partially-equalized magneto-optical signal 911 is output, and based on the result, Next, the state criterion of the maximum likelihood estimator 905 is sequentially communicated.

As described above, in the present embodiment, for the same reason as in the first embodiment, by using the clock generation mark provided on the optical disk of the sample servo system,
By avoiding a decrease in storage capacity caused by providing a special area for a training sequence for estimating reproduction characteristics, and performing an adaptive operation using the reflected light amount signal 21, the tap coefficient and the maximum likelihood of the equalizer 904 are obtained. It is possible to reliably set the initial state of the criterion of the estimator 905. Further, by controlling the criterion of the maximum likelihood estimator 905 using the magneto-optical signal 22, a finer adaptive operation can be performed.

[0069]

As described above, according to the optical disk device of the first aspect of the present invention, the optical disk device is a rewritable optical disk device, which is recorded in an embossed manner so as to be detected at a constant time interval. By using a signal having a high signal-to-noise ratio by having a data judgment unit including an adaptive operation circuit that dynamically changes tap coefficients and judgment criteria using a signal caused by non-rewritable information for clock generation Since the adaptive operation can be performed, an advantageous effect that a stable adaptive operation can be performed without particularly providing a region for the training sequence on the recording medium is obtained.

According to the optical disk device of the second aspect, in the optical disk device of the first aspect, the adaptive operation circuit is an equalizer using a transversal filter, so that the equalizer is capable of detecting fluctuations in reproduction characteristics. The advantageous effect of being able to cope is obtained.

According to the optical disk device of the third aspect, in the optical disk device of the first aspect, since the adaptive operation circuit is a maximum likelihood estimator, the criterion of the maximum likelihood estimator is dynamically updated. By doing so, an advantageous effect that fluctuations in reproduction characteristics can be dealt with can be obtained.

According to the optical disk device of the fourth aspect, in the optical disk device of the first aspect, the adaptive operation circuit is an equalizer using a transversal filter and a maximum likelihood estimator. By simultaneously performing the adaptive operation and the updating of the determination criterion of the maximum likelihood estimator, an advantageous effect that the amount of noise amplification and the equalization error by the equalizer can be reduced can be obtained.

According to the optical disk device of the fifth aspect, in the optical disk device of the second aspect, the maximum likelihood estimator is provided after the equalizer, so that the amount of noise amplification by the equalizer can be reduced. By fixing the determination criterion of the maximum likelihood estimator while reducing the equalization error, an advantageous effect that the complexity of the circuit can be avoided can be obtained.

According to the optical disk device of the sixth aspect, in the optical disk device of the third aspect, a tap coefficient fixed type equalizer is provided at a stage preceding the maximum likelihood estimator. By using a rectifier and limiting the increase in the internal state of the maximum likelihood estimator, an advantageous effect that circuit complexity can be avoided can be obtained.

According to the optical disk apparatus of the present invention, there is provided a rewritable optical disk apparatus, wherein a signal originating from non-rewritable information recorded in an embossed manner and a rewritable optical disk are detected so as to be detected at predetermined time intervals. By having a data decision unit that includes an adaptive operation circuit that dynamically changes tap coefficients and criteria using signals derived from information, it is possible to perform adaptive operations that take into account characteristic fluctuations during rewritable information reproduction. The advantageous effect that it can be obtained is obtained.

According to the optical disk device of the eighth aspect, in the optical disk device of the seventh aspect, the adaptive operation circuit is an equalizer using a transversal filter. An advantageous effect that fluctuation can be compensated is obtained.

According to the optical disk device of the ninth aspect, in the optical disk device of the seventh aspect, since the adaptive operation circuit is a maximum likelihood estimator, the criterion of the maximum likelihood estimator is dynamically changed. By doing so, an advantageous effect that all fluctuations in the reproduction characteristics can be compensated can be obtained.

According to the optical disk apparatus of the tenth aspect, in the optical disk apparatus of the seventh aspect, since the adaptive operation circuit is an equalizer using a transversal filter and a maximum likelihood estimator, By dynamically changing the tap coefficient and the determination criterion of the maximum likelihood estimator, an advantageous effect that all the fluctuations of the reproduction characteristics can be compensated can be obtained.

According to the eleventh aspect of the present invention, in the optical disk device of the seventh aspect, the adaptive operation circuit converts the non-rewritable information recorded by the emboss method so as to be detected at a constant time interval. Maximum likelihood estimator that dynamically changes tap coefficients and judgment criteria using the signal information caused by it, and equalizer that dynamically changes tap coefficients and judgment criteria using the signal caused by the rewritable information Has the advantageous effect that the maximum likelihood estimator can cope with the characteristic fluctuation during the period when the adaptive operation is not performed and the equalization error can be reduced.

According to the optical disk device of the twelfth aspect, in the optical disk device of the seventh aspect, the adaptive operation circuit converts the non-rewritable information recorded by the emboss method so as to be detected at a constant time interval. An equalizer that dynamically changes tap coefficients and criteria using the signal information caused by the signal, and a maximum likelihood estimator that dynamically changes tap coefficients and criteria using the signal caused by the rewritable information Has an advantageous effect that it is possible to cope with a characteristic variation during a period when the equalizer does not perform the adaptive operation and to reduce the probability of erroneous determination.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a data determination unit in FIG. 1;

FIG. 3 is a block diagram showing a data judging unit of a sample servo type magneto-optical disk reproducing device constituting an optical disk device according to a second embodiment of the present invention;

FIG. 4 is a block diagram showing a data judging unit of a sample servo type magneto-optical disc reproducing device constituting an optical disc device according to a third embodiment of the present invention;

FIG. 5 is a block diagram showing a data judging unit of a sample servo type magneto-optical disk reproducing device constituting an optical disk device according to a fourth embodiment of the present invention;

FIG. 6 is a block diagram showing a data judging unit of a sample servo type magneto-optical disk reproducing device constituting an optical disk device according to a fifth embodiment of the present invention;

FIG. 7 is a block diagram showing a data judging unit of a sample servo type magneto-optical disc reproducing device constituting an optical disc device according to a sixth embodiment of the present invention;

FIG. 8 is a block diagram showing a data judging unit of a sample servo type magneto-optical disk reproducing device constituting an optical disk device according to a seventh embodiment of the present invention;

FIG. 9 is a format diagram showing a format structure of a recording medium.

FIG. 10 is a block diagram showing a conventional optical disk device.

FIG. 11 is a servo area diagram showing an example of a servo area of an optical disk employing a sample servo tracking method.

FIG. 12 is a timing chart showing a reproduced RF signal in the servo area shown in FIG. 11;

13A is a timing chart showing the principle of tracking error detection using the servo area shown in FIG. 11; FIG. 13B is a timing chart showing the principle of tracking error detection using the servo area shown in FIG. 11; Timing diagram showing the principle of tracking error detection using the indicated servo area

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Recording medium 2 Optical detection system 3 Clock generation part 4 Address decoding part 5 Tracking control part 6 Data judgment part 7, 8 Low-pass filter 9 Automatic amplitude adjustment circuit 10, 11 Sampling circuit 101, 601, 701, 801 Impulse response estimation 102, 705 Inter-symbol interference amount estimation filter 103, 706 Binary decision unit 104, 402, 501, 702, 703, 802, 8
04, 902 Tap coefficient controller 401, 901 Reproduction characteristic estimator 403, 602, 803, 903 Criterion controller 404, 502, 603, 704, 806, 904 Equalizer 405, 503, 604, 807, 905 Maximum likelihood Estimator 805 Feedback filter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 20/18 520 G11B 20/18 520E 522 522Z 572 572D 572F 574 574J

Claims (12)

[Claims] 1. A rewritable optical disk device, comprising:
A data determination unit including an adaptive operation circuit that dynamically changes tap coefficients and determination criteria using a signal caused by non-rewritable information for clock generation recorded in an embossed manner so as to be detected at a fixed time interval. An optical disk device comprising: 2. The optical disk device according to claim 1, wherein the adaptive operation circuit is an equalizer using a transversal filter. 3. The optical disk device according to claim 1, wherein said adaptive operation circuit is a maximum likelihood estimator. 4. The optical disk apparatus according to claim 1, wherein said adaptive operation circuit is an equalizer using a transversal filter and a maximum likelihood estimator. 5. The optical disk device according to claim 2, further comprising a maximum likelihood estimator at a stage subsequent to said equalizer. 6. The optical disk device according to claim 3, further comprising an equalizer of a fixed tap coefficient type preceding said maximum likelihood estimator. 7. A rewritable optical disk device, comprising:
An adaptive operation circuit that dynamically changes tap coefficients and determination criteria using a signal caused by non-rewritable information and a signal caused by rewritable information recorded in an embossed manner so as to be detected at a fixed time interval. An optical disk device comprising a data determination unit including: 8. The optical disk apparatus according to claim 7, wherein said adaptive operation circuit is an equalizer using a transversal filter. 9. The optical disk device according to claim 7, wherein said adaptive operation circuit is a maximum likelihood estimator. 10. The optical disk apparatus according to claim 7, wherein said adaptive operation circuit is an equalizer using a transversal filter and a maximum likelihood estimator. 11. The adaptive operation circuit dynamically changes a tap coefficient and a determination criterion using a signal signal resulting from non-rewritable information recorded by an emboss method so as to be detected at a predetermined time interval. The optical disc apparatus according to claim 7, further comprising: a maximum likelihood estimator; and an equalizer that dynamically changes a tap coefficient and a criterion using a signal derived from the rewritable information. 12. The adaptive operation circuit dynamically changes a tap coefficient and a judgment criterion by using a signal signal resulting from non-rewritable information recorded by an emboss method so as to be detected at a predetermined time interval. The optical disc apparatus according to claim 7, further comprising: an equalizer; and a maximum likelihood estimator that dynamically changes a tap coefficient or a criterion using a signal resulting from the rewritable information.