KR100253804B1 - Method for controlling optical reproduction signal equalization and device thereof - Google Patents

Abstract

The present invention relates to a method and apparatus for controlling equalization of a signal reproduced from an optical record carrier.

The equalization control method of the optical reproduction signal of the present invention includes a first step of detecting the width of the output signal by dividing the output signal from the equalizer by recording units, and the minimum value of the value of the signal width detected in the first step; And a second step of comparing the minimum value of the previous signal width, and a third step of controlling to change the equalization characteristics of the equalizer according to the comparison result in the second step.

An equalization control apparatus for an optical reproduction signal of the present invention includes pickup means for converting information recorded on an optical disc into an electrical signal, an equalizer for equalizing an output signal from the pickup means according to a preset equalization characteristic, and from the equalizer. Signal width detection means for detecting a signal width by dividing the output signal of each signal by recording units, comparison means for comparing a minimum value of the signal width values detected by the signal width detection means with a minimum value of a previous signal width, and the comparison means. And control means for changing the equalization characteristics of the equalizer in accordance with the result.

Description

Equalization control method of optical reproduction signal and apparatus therefor

1 is a block diagram of a conventional optical reproduction signal equalizer.

FIG. 2 is a waveform diagram of a reproduction signal before equalization in the optical reproduction signal equalizer shown in FIG.

3 is a filtering characteristic diagram of an equalizer at 1x speed in the optical reproduction signal equalizer shown in FIG.

4 is a filtering characteristic diagram of an equalizer at 10 times speed in the optical reproduction signal equalizer shown in FIG.

FIG. 5 is a waveform diagram of a reproduction signal after equalization in the optical reproduction signal equalizer shown in FIG.

6 is a block diagram of an optical reproduction signal equalization control device according to an embodiment of the present invention.

7 is an output waveform diagram of each part in the optical reproduction signal equalization control device shown in FIG.

8 is a filtering characteristic diagram of an equalizer in the optical reproduction signal equalization control device shown in FIG.

* Explanation of symbols for main parts of the drawings

10: spindle motor 20: optical disk

30: optical pickup 40: equalizer

50: comparator 60: low pass filter

70: edge detector 80: counter

90: Windows 100: First register

110: second register 120: comparator

130: control unit

The present invention relates to a method and an apparatus for controlling equalization of a signal reproduced from an optical recording medium.

In general, an optical disc such as a compact disc (hereinafter referred to as a CD) or a digital video disc (hereinafter referred to as a DVD) may represent information by a series of pits formed in the track direction on an information recording surface. have. In other words, the optical disc has a length of the pit and an interval between the pit. This means that the length of the pit and the interval between the pit have various lengths depending on the information recorded. For example, the length of the pit and the interval between the pit are 3T to 11T for CD and 3T to 14T for DVD.

The information signal expressed by the length of the pit and the interval between the pits is obtained by using the amount of light reflected from the recording surface of the optical disk after being irradiated by a single wavelength light source such as a laser beam. In detail, when the laser light is irradiated on the recording surface without a pit, most of the irradiated light is reflected by the recording surface to generate a large amount of reflected light, and when the laser light is irradiated on the pit portion, a small amount due to the interference effect. Only reflected light is generated. At this time, the reflected light is converted into an electrical signal by the pickup device to become a read signal.

FIG. 1 is a block diagram of a conventional optical reproduction signal equalizer. The optical reproduction signal equalizer shown in FIG. 1 includes a spindle motor 10 for generating power for rotation of the optical disc 20, and the optical disc. 20, an optical pickup 30 for converting the reflected light into an electrical signal by scanning a light beam, and an equalizer 40 for correcting a signal size depending on the pit length by equalizing the signal input from the optical pickup 30. ).

In the optical reproduction signal equalizer of FIG. 1, the optical pickup 30 scans a light beam to the optical disk 20 rotated by the spindle motor 10, converts the light reflected from the optical disk 20 into an electrical signal, and then converts the optical signal into an electrical signal. Frequency; hereafter referred to as RF. In this case, as shown in FIG. 2, the RF signal reproduced by the optical pickup 30 does not have a constant magnitude depending on the frequency. This is because a small high frequency signal is reproduced when the pit length formed on the recording surface of the optical disc is short, and a low frequency signal having a large size is reproduced when the pit length is long. Such an RF signal is corrected to an RF signal having a different frequency component but a constant magnitude as shown in FIG. 5 while passing through the equalizer 40. This is shown in FIG. 3 so that the equalizer 40 can compensate for the signal size reproduced from the pits of lengths 10T to 3T thereafter on the basis of 11T feet having the maximum reproduced signal size. That means you have a different gain for that frequency, ie for each pit.

Then, the optical reproduction signal equalizer is a perfect sphere of the RF signal output from the equalizer 40 based on the low pass filter 60 for detecting the center of the RF signal, and the center value from the low pass filter 60 Comparator 50 for outputting a signal in the form of a pulse.

The RF signal corrected by the equalizer 40 is compared with the center value of the reproduction signal detected from the low pass filter 60 in the comparator 50, so that a signal in the form of a perfect square pulse, that is, EFM (Eight to Fourteen Modulation) ) Is output as a signal.

However, in the equalizer 40 of the conventional optical reproduction signal equalizer as described above, the frequency band of the reproduction signal is changed because the band filtering characteristic is fixed as shown in FIG. 3 or FIG. If there was a problem was not suitable. This is described in detail as follows.

The method of recording information on an optical disc includes the CAV (Constant Angular Velocity) method, which records information at a constant bit rate while maintaining a constant rotation speed of the optical disc, and the rotation speed of the optical disc varies depending on the track position. The CLV (Constant Liner Velocity) method of recording information at a constant bit rate is widely known. Here, the CAV method is advantageous in that data can be reproduced at the same rotational speed without distinguishing between the outer track and the inner track of the optical disk, and the CLV method has a constant linear speed by increasing the rotational speed toward the inner track direction. Since information is recorded in the state, it is advantageous in terms of being able to record more information than the CAV method.

In order to reproduce an optical disc on which information is recorded in the CLV method, the rotation speed of the inner and outer tracks of the optical disc must be different. This is to maintain a constant linear velocity, which means that the rotation speed on the inner track should be faster than on the outer track. For example, in the case of a compact disc, the speed of rotating the optical disc in the playback device is about 500 rpm in the innermost track and about 200 rpm in the outermost track when the data is played back at standard speed. have.

Recently, CD-ROM discs play data at four times the standard, 4 times, 8 times, 10 times, 12 times, 16 times, 20 times, and 24 times higher than the standard, and 2 times and 3 times the standard for DVD-ROM. A technique for reproducing at a high speed such as 4 times, 4 times, etc. has been developed. The biggest technical problem in realizing such a high speed reproducing technology is controlling the rotation speed of the optical disc and restoring data from a reproducing signal whose frequency is frequently changed accordingly. It is a problem. For example, in the case of a 10x CD-ROM disc using the CLV method, in order to read data at 10x speed (1500KB / Sec), it is about 5000rpm at the innermost track of the optical disc, and 2000rpm at the outermost track. Should be rotated. At this time, when the pickup is moved from the outermost track of the optical disc to the innermost track in order to reproduce data from the outermost track of the optical disc, the rotation speed of the optical disc should be increased from 2000 rpm to 5000 rpm. However, it takes considerable time to raise the optical disc to the target rotational speed of 5000 rpm, and data cannot be read during this letter. This is because the rotation speed of the optical disc is slower than the reference speed in the state of accelerating the rotation speed, and thus, a PLL (Phase Lock Loop) range is provided to detect a synchronous pulse of an accurate reproduction signal by giving a high-speed fixed clock for demodulation of data. It means that the data cannot be read or read. The same problem occurs in the case where the optical disc is moved from the inner circumference to the outer circumference and played back. To solve this problem, recently, the PLL can be locked when the rotation speed of the disc is slower or faster than the reference speed by using a wide PLL method or a CAV method.

However, in the transient state, that is, when the rotational speed of the optical disc is slower or faster than the reference speed, the frequency band of the signal reproduced from the pit of the disc moves to the low frequency or high frequency band. At this time, the equalizer has to adjust the filtering characteristics according to the frequency band of the reproduction signal. The conventional equalizer has a filtering characteristic fixed in a circuit and operates regardless of the frequency band change. As a result, the band-filtering characteristics of the equalizer do not match, thereby making the reproduction signal more unbalanced and causing an error in restoring the original signal. Therefore, it is necessary to adjust the characteristics of the equalizer so that the filtering can be controlled. Until recently, the method of adjusting the characteristics of the equalizer is controlled through several steps of switching as previously determined from the external microcomputer. It was not possible to cope with the change in the frequency band of.

As described above, even if the PLL follows the wide PLL or CAV method when the disk rotation speed changes faster or slower than the reference speed, deterioration due to the shift of the frequency band of the playback signal itself is inevitable. As a result, an error occurs during data restoration, resulting in a prolonged access time and a decrease in data reproduction performance.

An object of the present invention is to solve such a conventional technical problem, by automatically adjusting the band filtering characteristics of the equalizer in accordance with the variation of the frequency band of the reproduction signal generated in the transient state in which the rotational speed of the optical disk is added or subtracted. An object of the present invention is to provide an equalization control method and an apparatus for an optical reproduction signal that can always perform optimal equalization.

SUMMARY OF THE INVENTION An object of the present invention is to provide an equalization control method and apparatus for an optical reproduction signal which automatically adjusts the filtering characteristics of an equalizer according to a change in a frequency band caused by a change in a reproduction scheme so that an optimal equalization can always be performed. There is.

It is still another object of the present invention to provide an equalization control method and apparatus for an optical reproduction signal capable of accelerating an access time by performing optimal equalization in a transient state in which the rotational speed of the disc is accelerated and decelerated during track search.

In order to achieve the above object, the equalization control method of the optical reproduction signal of the present invention comprises the first step of detecting the width of the output signal by dividing the output signal from the equalizer by recording units; And a second step of comparing the minimum value of the detected signal width with the minimum value of the signal width according to the previous equalization characteristic, and a third step of controlling the equalization characteristic of the equalizer according to the comparison result in the second step. It is characterized by.

In addition, the equalization control method of the optical reproduction signal of the present invention includes a first step of detecting the width of the output signal by dividing the output signal from the equalizer by recording units, and the value of the signal width detected in the first step. And a third step of comparing the maximum value with the maximum value of the signal width according to the previous equalization characteristic, and a third step of controlling the equalization characteristic of the equalizer according to the comparison result in the second stage. .

The equalization control apparatus of the optical reproduction signal of the present invention includes pickup means for converting information recorded on an optical disc into an electrical signal, equalizer for equalizing the output signal from the pickup means according to preset equalization characteristics, and the equalization. Signal width detection means for detecting a signal width by dividing the output signal from the signal by recording units; and comparison means for comparing a minimum value of the signal width detected by the signal width detection means with a minimum value of a previous signal width; And control means for changing the equalization characteristics of the equalizer in accordance with the result of the comparison means.

An equalization control apparatus for an optical reproduction signal of the present invention includes pickup means for converting information recorded on an optical disc into an electrical signal, an equalizer for equalizing an output signal from the pickup means according to predetermined equalization characteristics, and the equalizer. Signal width detection means for detecting a signal width by dividing the output signal from the recording unit by recording units; and comparing means for comparing the maximum value of the signal width detected by the signal width detection means with the maximum value of the machine signal width; And control means for changing the equalization characteristics of the equalizer in accordance with the result of the comparison means.

The above and other objects and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. Shall be.

6 is a block diagram of an equalization control apparatus of an optical reproduction signal according to an embodiment of the present invention. In the embodiment of the present invention, parts having the same function and configuration as those of the conventional optical reproduction signal equalizer shown in FIG. 1 are represented by the same reference numerals. The apparatus for controlling equalization of the optical regeneration signal shown in FIG. 6 includes a spindle motor 10 generating power for rotation of the optical disc 20 and electrical light reflected by scanning a light beam onto the optical disc 20. An optical pickup 30 for converting to a signal, an equalizer 40 for correcting a signal size depending on the pit length by equalizing the signal input from the optical pickup 30, and a row for detecting the center of the RF signal A pass filter 60 and a comparator 50 for comparing the center value from the low pass filter 60 with the reproduction signal output from the equalizer 40 and outputting a reproduction signal in the form of a perfect square pulse.

When the optical disk 20 is rotated by the spindle motor 10, as in the related art, the information signal is reproduced by the optical pickup 30 and corrected as a signal having the same size by the filtering operation of the equalizer 40. Thereafter, the comparator 50 is compared with the center value of the low pass filter 60 and outputted as an EFM signal in the form of a complete rectangular pulse.

The equalization control device of the optical reproduction signal is controlled by an edge detector 70 for detecting an edge component of the output signal EFM from the comparator 50 and an impulse signal output from the edge detector 70. A counter 80 is set and counted. The edge detector 70 and the counter 80 detect the width of the signal output from the comparator 50.

In detail, the final reproduction signal EFM output from the comparator 50 forms a pulse train having various pulse widths as shown in FIG. 7. As illustrated in FIG. 7, the edge detector 70 detects only an edge component of the EFM signal output from the comparator 50 and outputs it to the counter 80 as a reset signal Reset. The counter 80 counts the pulse width of the EFM signal and the interval between pulses based on a reset signal output from the edge detector 70, that is, a small clock that is reset by an impulse signal and applied from the outside. Detect the width of the EFM signal.

In addition, the equalization control device of the optical reproduction signal detects a predetermined number of count values from the counter 80, outputs a double minimum value to the first register 100, and stores the previous signal width value. The stored second register 110 and the values stored in the first and second registers 100 and 110 are compared with each other to update the value of the second register 110 when the two values are different from each other. Comparator 120 and an equalizer control unit 130 for setting the optimal equalization characteristics using the values stored in the second register 110.

The window unit 90 receives a predetermined number, for example, 100 count values from the counter 80 for a predetermined time, and stores the smallest value in the first register 100 as a value of the minimum recording feet 3T. Let's do it. The comparator 120 has a value of the minimum recording feet 3T stored in the first register 100 and a value stored in the second register 110, that is, a value of the minimum recording feet 3T according to the characteristics of the previous equalizer. Are compared to each other. The comparator 120 outputs a load enable signal to the second register 110 when the two values, that is, the value of the currently detected 3T signal width and the previous 3T signal width, are different from each other. The value of the second register 110 is updated to the value stored in the first register 100.

Here, the case where the value of the currently detected 3T signal width compared with the value of the previous 3T signal width compared in the comparator 120 is as follows. First, when the optical pickup 30 moves from the inner circumference of the optical disk 20 to the outer circumference, the signal width detected at the outer circumference is shorter than the inner circumference without the rotation speed of the optical disk 20 being decelerated to the reference speed. This is the case when a value smaller than the previous stored value comes in. In addition, when the optical pickup 30 moves from the outer circumference of the optical disk 20 to the inner circumference, the signal width detected at the inner circumference is larger than the outer circumference without the rotational speed of the optical disk 20 being accelerated to the reference speed. This is the case when a value larger than the stored value comes in.

The controller 130 adjusts the band filtering characteristic of the equalizer 40 to correspond to the new value stored in the second register 110. In other words, the controller 130 adjusts the equalizer 40 as shown in FIG. 8 to adjust the filtering characteristics of the equalizer 40 to the detected signal when the second register 110 is updated. Adjust the frequency (fa, fb) and gain (g). Such adjustment is possible by the controller 130 applying a voltage corresponding to the gain of the equalizer 40 and a current corresponding to the frequency. At this time, the optimum filtering characteristic of the equalizer 40 is mapped and stored in the internal memory of the controller 130.

In this way, the filtering characteristics of the equalizer are adaptively changed in accordance with the change of the frequency band of the reproduction signal generated in the acceleration / deceleration transient of the rotational speed of the optical disc, so that the equalizer 40 always has a signal having the same magnitude as the reproduction signal. Can be corrected accurately. In addition, even if the frequency band of the reproduction signal is changed due to the change of the reproduction method in which part of the disc is reproduced by the CLV method and the CAV method, the equalization can be performed by varying the filtering characteristics of the equalizer.

The comparator 120 is compared based on the minimum recording feet 3T value, but the same effect can be obtained even on the basis of the maximum recording feet value (11T for CD and 14T for DVD).

As described above, according to the equalizing control method and apparatus of the optical reproduction signal according to the present invention, the equalization is performed in accordance with the frequency band variation of the reproduction signal generated in the rotational speed acceleration / deceleration transient of the optical disc during reproduction of information recorded on the optical disc. By adaptively varying the filtering characteristics of the group, the equalizer always has the effect of performing optimal equalization. As a result, accurate information can be reproduced from the optical disc even in the rotational speed acceleration / deceleration time, thereby reducing the access time.

It will be appreciated by those skilled in the art that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (22)

(Correcting) detecting the width of the output signal by dividing the output signal from the equalizer by the size of the recording pits on the optical disc; A second step of comparing the minimum value of the signal width according to the previous gain of the equalizer with the minimum value of the signal width values detected in the first step; And a third step of controlling the gain of the equalizer to be changed according to the comparison result in the second step. The method of claim 1, wherein the detection of the signal width is performed by detecting an edge component of the signal and counting a predetermined clock between edge components. . The equalization control of the optical reproduction signal according to claim 1, wherein the minimum value detected in the second step is the smallest value among the values of the signal width detected in the first step for a predetermined number of times. Way. The method according to claim 1, wherein the step (2) further comprises updating the previous minimum value to the detected minimum value when the two compared values are different. (Correct) The equalization control method according to claim 1, wherein the gain of the equalizer is adjusted according to a frequency in the third step. A first step of detecting the width of the output signal by dividing the output signal from the equalizer by the size of the recording pits on the optical disc; A second step of comparing the maximum value of the signal width according to the previous gain of the equalizer with the maximum value of the signal width values detected in the first step; And a third step of controlling the gain of the equalizer to be changed according to the comparison result in the second step. 7. The equalization control method according to claim 6, wherein the detection of the signal width in the first step is performed by detecting an edge component of the signal and counting a predetermined clock between edge components. . 7. The equalization of the optical reproduction signal according to claim 6, wherein the maximum value detected in the second step is the largest value among the values of the signal width detected in the first step for a predetermined number of times. Control method. 7. The equalization control method according to claim 6, wherein the step (2) further comprises a step of updating the previous maximum value to the detected maximum value when the two compared values are different. (Correct) The equalization control method according to claim 6, wherein the gain of the equalizer in the third step is adjusted according to a frequency. (Correction) pickup means for converting information recorded on the optical disc into an electrical signal; An equalizer for equalizing the output signal from the pickup means according to a preset gain; Signal width detecting means for detecting a signal width by dividing the output signal from the equalizer by the size of the recording pits on the optical disc; Comparison means for comparing a minimum value of the signal widths detected from the signal width detection means with a minimum value of the signal width according to a previous gain of the equalizer; And control means for changing a gain of the equalizer in accordance with the result of the comparing means. 12. The apparatus of claim 11, wherein the signal width detecting means comprises: a low pass filter for detecting a center of an output signal from the equalizer; A comparator for outputting the output signal from the equalizer as a complete rectangular pulse signal based on the center value from the low pass filter; Edge detection means for detecting an edge component of the signal output from said comparator and outputting it as a reset signal; And a counter which is reset by a reset signal input from said edge detecting means and counts a width of a signal output from said comparator on the basis of a predetermined clock. (Correction) The apparatus according to claim 11, wherein the comparing means comprises: window means for outputting a minimum value among values which have received a predetermined number of values of the signal width detected from the signal width detecting means for a predetermined time; First storage means for storing the minimum value output from the window means; Second storage means for storing a minimum value of a signal width according to a previous gain of the equalizer; And a comparator for comparing the values stored in the first and second storage means with each other and applying a load enable signal to the second storage means when the two values are different from each other. The apparatus of claim 13, wherein the second storage means is updated to a minimum value of the first storage means when the load enable signal is applied from the comparator. (Correction) The equalization control apparatus for optical reproduction signal according to claim 11, wherein the control means adjusts the gain of the equalizer in accordance with a frequency. (Correction) The equalization control apparatus according to any one of claims 11 to 15, wherein the gain according to the frequency is mapped to an internal memory of the control means. (Correction) pickup means for converting information recorded on the optical disc into an electrical signal; An equalizer for equalizing the output signal from the pickup means according to a preset gain; Signal width detecting means for detecting a signal width by dividing the output signal from the equalizer by the size of the recording pits on the optical disc; Comparison means for comparing the maximum value of the signal widths detected from the signal width detection means with the maximum value of the signal width according to the previous gain of the equalizer; And a control means for changing a gain of the equalizer in accordance with the result of the comparing means. 18. The apparatus of claim 17, wherein the signal width detecting means comprises: a low pass filter for detecting the center of the output signal from the equalizer; A comparator for outputting the output signal from the equalizer as a complete rectangular pulse signal based on the center value from the low pass filter; Edge detection means for detecting an edge component of the signal output from said comparator and outputting it as a reset signal; And a counter which is reset by a reset signal input from the edge detection means and counts a width of a signal output from the comparator on the basis of a predetermined clock. (Correction) The apparatus according to claim 17, wherein the comparing means comprises: window means for outputting a maximum value among values which receive a predetermined number of values of the signal width detected from the signal width detecting means for a predetermined time; First storage means for storing the maximum value output from the window means; Second storage means for storing a maximum value of a signal width according to a previous gain of the equalizer; And a comparator for comparing the values stored in the first and second storage means with each other and applying a load enable signal to the second storage means when the two values are different from each other. 20. The apparatus of claim 19, wherein the second storage means is updated to a maximum value of the first storage means when the load enable signal is applied from the comparator. (Correction) The equalization control apparatus for optical reproduction signal according to claim 17, wherein the control means adjusts the gain of the equalizer in accordance with a frequency. 22. The equalization control apparatus according to any one of claims 17 and 21, wherein the gain according to the frequency is mapped to an internal memory of the control means.

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