KR100219594B1 - Recording/reproducing apparatus and method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for playing back a recording signal of an optical disc, and has been devised to solve the conventional problem of applying a complicated equalizer.

The present invention provides a beam irradiator for irradiating a predetermined amount of beams to an optical disk; A light detector for converting the beam reflected from the optical disk into an electrical signal; An amplifier for amplifying the electrical signal with a predetermined amplification degree; A comparator for converting the amplified signal into a digital signal; An edge pulse generator for obtaining a rising edge pulse and a falling edge pulse of the digital signal; And a timing decision part for outputting the falling edge pulse at the time when the rising edge pulse is output and then adjusted according to a substantial time for the pulse width. It can fundamentally prevent edge movement and jitter.

Description

Method and apparatus for reproducing recording signal of optical disc

1 is a timing diagram for explaining the left side movement of the edge.

2 is a timing diagram for explaining a conventional optical disc reproducing method.

3 is a schematic block diagram for explaining a conventional optical disc reproducing apparatus.

4 is a timing diagram for explaining an optical disk reproducing method according to the present invention.

5 is a schematic block diagram for explaining an optical disc reproducing apparatus according to the present invention.

6 is an exemplary diagram for describing a comparator of FIG. 5.

FIG. 7 is an exemplary diagram for describing the edge detector of FIG. 5.

FIG. 8 is a timing diagram for explaining the signal relationship of FIG.

FIG. 9 is a circuit diagram showing the timing determining unit of FIG.

FIG. 10 is a timing diagram of a process of preventing edge movement to the left in FIG. 9.

FIG. 11 is a timing diagram of a process of preventing edge movement to the right in FIG. 9.

* Explanation of symbols for main parts of the drawings

1a, 2a, 4a: recording data 1b, 2b, 4b: recording signal

1c, 2f: Normal playback signal 1d: Playback signal edge-shifted to the left

1e: Playback signal edge shifted to the right

2d: Playback signal edge shifted left or right

2c, 4c: Amplified signal 4d: Digital signal

4e: edge pulse 4f: rising edge pulse

4g: falling edge pulse 4h: first clock pulse

4i: second clock pulse 4j: primary playback signal

4k: secondary playback signal 1: optical disc

2: photodiode 3: regenerative amplifier

7: laser diode 8: optical modulator

9: comparator 10: edge detector

11 edge PLL (Phase Locked Loop) 12: timing determining section

13: delay element

14: Exclusive OR gate

15: RS flip-flop 16: counter portion

17: first gate circuit 18: pattern detector

19: latch portion 20: falling edge pulse storage portion

21: second gate circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for reproducing a recording signal of an optical disc, and more particularly, to a non-return signal recorded on an optical disc such as a compact disc or a magneto-optical disc. and a method and apparatus for reproducing a signal).

Digital data recording / reproducing systems using optical discs include magnet-optical disc drives (MODDs), digital video disc recorders (DVDRs), and compact disc players (CDPs), which are reproduction-only systems. In such a recording / reproducing system, the signal 1b recorded on the optical disk is a non-return to zero signal, and the recording data (1) becomes a logical '1' only when its state is inverted. 1a). Therefore, the non-zero return signal should be converted into a conventional digital signal. Such a signal conversion process is called a playback.

Common reproducibility of non-return signals recorded on optical discs is edge shift and jitter. Edge shift is due to the peak shift that appears when the reflected beam from the optical disc is converted into an electrical signal. 1 is a timing diagram for explaining edge movement. In FIG. 1, 1a represents recording data, 1b represents a recording signal, 1c represents a normal reproduction signal, 1d represents a reproduction signal edge shifted to the left, and 1e represents a reproduction signal shifted to the right. As shown in FIG. 1, in general, the period between the rising edge and the falling edge of the recording signal appears constant, but the period between the rising edge and the falling edge is not constant. appear. On the other hand, as the jitter values at the rising edge and the falling edge of the recording signal are different from each other, the degradation of the characteristics of the signal is accelerated.

In order to reproduce the signal recorded on the optical disc while preventing the edge movement, conventionally, a method of equalizing the output signal of the reproduction amplifier and then detecting the edge of the equalized signal has been selected. 2 is a timing diagram for explaining a conventional optical disc reproducing method. In Fig. 2, reference numeral 2a denotes recording data of an optical disc, and reference numeral 2b denotes a recording signal according to the recording data 2a. In order to reproduce such a recording signal, a process of irradiating a constant amount of light onto the optical disc, converting the reflected light into an electrical signal, and then amplifying it appropriately is necessary. However, the amplified signal, that is, the output signal (2c) of the reproduction amplifier is a phenomenon that the peak (peak) is not constant due to the waveform distortion caused by the interference between the signals. This phenomenon is called a peak shift, which results in an edge shift that results in a different phase of the reproduction signal. In Fig. 2, reference numeral 2d denotes an edge shifted reproduction signal. Accordingly, in order to prevent the peak shift, a method of equalizing the output signal of the reproducing amplifier and detecting the edge of the equalized signal 2e has been conventionally selected. In Fig. 2, reference numeral 2f denotes a reproduction signal without edge movement.

3 is a schematic block diagram for explaining a conventional optical disc reproducing apparatus. Looking at the operation process, first, a laser beam generated from the laser diode (7) is irradiated to the optical disk 1 by a predetermined amount through the optical modulator (8). Accordingly, the beam reflected from the optical disk 1 is converted into an electrical signal through a photo diode 2 and then amplified appropriately in the reproduction amplifier 3. Since the output signal of the reproducing amplifier 3 is in the peak shifted state, it is compensated by the equalizer 4, and then the edge detector 5 and the phase locked loop circuit 6 are applied to generate the reproducing signal. . Thus, a high performance equalizer 4 is needed to compensate for peak shifts.

According to the conventional method and apparatus for reproducing a recording signal of an optical disc as described above, the following problems are encountered. First, the internal circuit of the equalizer is complex. Second, there is a limit to the peak shift compensation that depends entirely on the high performance equalizer. And third, there is no means to fundamentally prevent jitter.

The present invention has been made to solve the above problems, and an object thereof is to provide a recording signal reproducing method and apparatus capable of fundamentally preventing edge movement and jitter without wearing an equalizer.

In order to achieve the above object, a recording signal reproducing method of an optical disk according to the present invention comprises the steps of: converting a reflected beam into an electrical signal while irradiating a predetermined amount of beam on the optical disk; Amplifying the electrical signal with a predetermined degree of amplification; Converting the amplified signal into a digital signal; Obtaining a rising edge pulse and a falling edge pulse of the digital signal; Obtaining a pulse width of the digital signal; And after outputting the rising edge pulse, outputting the falling edge pulse at a time adjusted according to a substantial time for the pulse width.

In addition, in order to achieve the above object, the recording signal reproducing apparatus of the optical disk according to the present invention comprises: a beam irradiator for irradiating a predetermined amount of beam to the optical disk; A light detector for converting the beam reflected from the optical disk into an electrical signal; An amplifier for amplifying the electrical signal with a predetermined amplification degree; A comparator for converting the amplified signal into a digital signal; An edge pulse generator for obtaining a rising edge pulse and a falling edge pulse of the digital signal; And a timing decision part for outputting the falling edge pulse at the time when the rising edge pulse is output and then adjusted according to a substantial time for the pulse width.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

4 is a timing diagram for explaining an optical disk reproducing method according to the present invention. As described above, the signal 4b recorded on the general optical disc is a non-return to zero signal, and has the recording data 4a which becomes a logic '1' only when its state is inverted. . Such a recording signal 4b can reproduce its shape by converting the reflected beam into an electrical signal while irradiating the optical disk with a certain amount of beam. Reference numeral 4c denotes a signal in which the electrical signal is amplified by a predetermined degree of amplification. Reference numeral 4d denotes a digital signal obtained by comparing the amplified signal 4c with a predetermined threshold voltage (Vth). Thereby, the edge pulse 4e which detected and detected the edge of the digital signal 4d can be divided into the rising edge pulse 4f and the falling edge pulse 4g. Reference numeral 4h denotes a first clock pulse having a bit period of the write data 4a, and reference numeral 4i denotes a second clock pulse in which the first clock pulse 4h is inverted. As described above, in the edge shift phenomenon, the period between the rising edge and the falling edge of the recording signal appears to be constant, but the period between the rising edge and the falling edge is not constant. Has characteristics. Therefore, using this edge movement characteristic, it is possible to fundamentally prevent edge movement. That is, after outputting the rising edge pulse 4f, what is necessary is just to output the falling edge pulse 4g according to the pulse width of the said digital signal 4d by applying stepwise time difference to the falling edge pulse 4g. For example, if the pulse width is relatively short, a relatively delayed falling edge pulse, if the pulse width is within a predetermined reference range, a relatively non-delayed falling edge pulse, and the pulse width is relatively If it is long, it is already stored and outputs the leading edge pulse 4g. On the other hand, as the jitter values at the rising edge and the falling edge of the recording signal are different from each other, the degradation of the characteristics of the signal is accelerated. Therefore, in order to prevent edge movement and jitter, after outputting the rising edge pulse 4f by applying the first clock pulse 4h or the second clock pulse 4i, the pulse width of the digital signal 4d is applied. What is necessary is just to output the said falling edge pulse 4g at the time adjusted according to the pulse width. Reference numeral 4j denotes a primary reproduction signal in which edge movement and jitter phenomenon are prevented, and reference numeral 4k denotes a secondary reproduction signal in which the pulse width of the primary reproduction signal 4j coincides with the bit period of the recording data 4a.

5 is a schematic block diagram for explaining an optical disc reproducing apparatus according to the present invention. In FIG. 5, the laser beam generated by the laser diode 7 is irradiated to the optical disk with a certain amount through the optical modulator 8. The beam reflected from the optical disc 1 is converted into an electrical signal in the photodiode 2, and the electrical signal is amplified by a predetermined degree of amplification in the reproduction amplifier 3. The comparator 9 converts the amplified analog signal into a digital signal. 6 is an exemplary diagram for describing a comparator of FIG. 5. As shown in FIG. 6, the output signal of the regenerative amplifier 3 is input to the plus terminal of the comparator, and a predetermined threshold voltage Vth is applied to the negative terminal. Accordingly, when the instantaneous value of the output signal is higher than the threshold voltage, a digital signal having a logic '1' state and a low value is output. The rising edge detector and the falling edge detector 10 respectively detect rising and falling edges of the digital signal, and rising edge PLL and falling edge PLL 11 have rising edge pulses having the same pulse width as the period of the recording data. And falling edge pulses, respectively. FIG. 7 is an exemplary diagram for describing the edge detector of FIG. 5. As shown in FIG. 7, an input signal, that is, an output signal of the comparator 9, is connected to one terminal of the delay element 13 and the exclusive NOR gate 14 having a predetermined delay time. It is input at the same time. On the other hand, the signal delayed by? In the delay element 13 is input to the other terminal of the exclusive NOR gate 14. FIG. 8 is a timing diagram for explaining the signal relationship of FIG. In FIG. 8, reference numeral 8a denotes a signal input to one terminal of the delay element 13 and the exclusive NOR gate 14, 8b an output signal of the delay element 13, and 8c an output signal of the exclusive NOR gate 14. Indicates. As shown, the output signal 8c of the exclusive NOR gate 14 is a rising edge and falling edge pulse having a pulse width of delay time τ at the rising edge and falling edge of the input signal, that is, the output signal of the comparator 9. Generates. The timing determining unit 12 outputs the rising edge pulse, and then outputs the falling edge pulse at a time point adjusted according to the time corresponding to the pulse width.

FIG. 9 is a circuit diagram showing the timing determining unit of FIG. As shown in FIG. 9, the timing determiner includes: an RS flip-flop 15 for generating an original waveform for rising and falling edge pulses; A counter unit 16 for counting the time when the output of the RS flip-flop 15 is in a logic '1' state; A first gate circuit unit 17 for combining the outputs of the counter unit 16 to generate sequential pulses for each bit period of the corresponding write data; A pattern detector 18 that detects a Variable Frequency Oscillator (VFO) pattern for rising and falling edge pulses; A latch unit 19 for outputting a corresponding pulse among the sequential pulses when the pattern is detected; A falling edge pulse storage unit 20 for sequentially storing falling edge pulses; And a second gate circuit portion 21 for generating a rising edge pulse after generating the rising edge pulse and generating the stored falling edge pulse according to the output pulse of the latch portion 19.

In the present embodiment, 74163 counter is applied as the counter 16 and 7475 latch is applied as the latch 19. The first gate circuit unit 17 includes three inverters and three AND gates 25, 26, and 27. The second gate circuit portion 21 includes three AND gates 28, 29, and 30 and one OR gate 31. In the falling edge pulse storage unit 20, three D flip-flops 22, 23, and 24 are connected in series, and the output of each D flip-flop is connected to three AND gates of the second gate circuit unit 21. Each is input.

Referring to the operation of FIG. 9, the three AND gates 25, 26, and 27 of the first gate circuit unit 17 are sequentially disposed at a logic '1' with a parallax of a 1-bit period of write data. You can see that it outputs a pulse. That is, the first AND gate 25 outputs a logic '1' pulse faster than the second AND gate 26 by one bit period of the write data and faster than the third AND gate 27 by two bit periods of the write data. . On the other hand, since the pattern detector 18 enables the latch unit 19 when the falling edge pulse occurs, the 1Q terminal of the latch unit 19 becomes a logic '1' when the falling edge pulse occurs relatively early. Outputs the state pulse. However, in order to output a pulse having a logic '1' state at the first AND gate 28 of the second gate circuit 21, the logic '1' state at the first flip-flop 22 of the falling edge pulse storage unit 20 is output. It should output pulse of. As a result, after a delay of one clock pulse, the first AND gate 28 of the second gate circuit 21 outputs a pulse having a logic '1' state, thereby preventing edge shift to the left.

If the falling edge pulse is generated at the same time as the falling edge of the recording pulse, the 2Q terminal of the latch unit 19 outputs a pulse having a logic '1' state. In addition, in order to output the logic of the logic '1' state from the second AND gate 29 of the second gate circuit 21, the logic '1' state of the second flip-flop 23 of the falling edge pulse storage unit 20. It should output pulse of. Accordingly, the pulse of the logic '1' state is output from the second AND gate 29 of the second gate circuit 21 without delay.

If the falling edge of the falling edge pulse is relatively slower than the falling edge of the recording pulse, the 3Q terminal of the latch unit 19 outputs the pulse of the logic '1' state. Here, since the pulse having the logic '1' state is already stored in the second flip-flop 23 of the falling edge pulse storage unit 20, one of the clock pulses is applied to the third AND gate 30 of the second gate circuit unit 21. The pulse of the logic '1' state is output before the period. Thereby, the edge movement to the right side can be prevented.

In addition, as the circuit is operated by one clock pulse, the jitter values at the rising edge and the falling edge of the recording signal are provided, thereby preventing deterioration of signal characteristics.

FIG. 10 is a timing diagram of a process of preventing edge movement to the left in FIG. 9. In Fig. 10, reference numeral 10a denotes a recording signal; 10b, a comparator (9 in Fig. 5) output signal; 10c is an output pulse of the rising edge detector (10 in FIG. 5); 10d is an output pulse of the falling edge detector (10 in FIG. 5); 10e is a rising edge pulse; 10f is a rising edge clock pulse; 10 g is a falling edge pulse; 10h is the falling edge clock pulse; 10i denotes an output signal of an RS flip-flop (15 in FIG. 9); 10j is a clock pulse of the counter section (16 in FIG. 9); 10k denotes output data of the counter section (16 in FIG. 9); 10 m is the output pulse of the third D flip-flop (24 of FIG. 9) of the falling edge pulse storage (20 of FIG. 9); 10n is the output pulse of the second D flip-flop (23 in FIG. 9) of the falling edge pulse storage (20 in FIG. 9); 10p is the output pulse of the first D flip-flop (22 in FIG. 9) of the falling edge pulse storage (20 in FIG. 9); 10q is a reproduction signal assuming a case of edge shift to the left; 10r indicates a reproduction signal output from the OR gate (31 in FIG. 9) of the second gate circuit section (21 in FIG. 9).

As illustrated in FIG. 10, the comparator (9 in FIG. 5) is caused by the peak shift generated when the recording signal 10a is reproduced through the photodiode (2 in FIG. 5) and the reproducing amplifier (3 in FIG. 5). ), The pulse width of the digital signal 10b outputted from N may be smaller than the pulse width of the recording signal 10a. As a result, as shown in the waveform of 10q, a reproduction signal edge-shifted to the left may be generated. However, according to the present invention, after the rising edge pulse 10e is output, the falling edge pulse 10g is outputted at a time point adjusted in accordance with the time corresponding to the pulse width of the digital signal 10b. The edge movement of 10r can be prevented.

FIG. 11 is a timing diagram of a process of preventing edge movement to the right in FIG. 9. In Fig. 11, reference numeral 11a denotes a recording signal; 11b, a comparator (9 in Fig. 5) output signal; 11c is an output pulse of the rising edge detector (10 in FIG. 5); 11d is the output pulse of the falling edge detector (10 in FIG. 5); 11e is a rising edge pulse; 11f is a rising edge clock pulse; 11 g is a falling edge pulse; 11h is the falling edge clock pulse; 11i is an output signal of the RS flip-flop (15 in FIG. 9); 11j denotes a clock pulse of the counter section (16 in FIG. 9); 11k denotes output data of the counter section (16 in FIG. 9); 11m is the output pulse of the third D flip-flop (24 of FIG. 9) of the falling edge pulse storage (20 of FIG. 9); 11n is the output pulse of the second D flip-flop (23 in FIG. 9) of the falling edge pulse storage (20 in FIG. 9); 11p is the output pulse of the first D flip-flop (22 in FIG. 9) of the falling edge pulse storage (20 in FIG. 9); 11q is a reproduction signal assuming the case of edge shift to the right; 11r indicates a reproduction signal output from the OR gate (31 in FIG. 9) of the second gate circuit section (21 in FIG. 9).

As illustrated in FIG. 11, the comparator (9 in FIG. 5) is caused by the peak shift generated when the recording signal 11a is reproduced through the photodiode (2 in FIG. 5) and the reproducing amplifier (3 in FIG. 5). ), The pulse width of the digital signal 11b outputted from the reference signal may be wider than the pulse width of the recording signal 11a. As a result, as shown in the waveform 11q, a reproduction signal edge-shifted to the right may be generated. However, according to the present invention, after the rising edge pulse 11e is outputted, the falling edge pulse 11g is outputted at a time point adjusted according to the pulse width of the digital signal 11b according to a considerable time. The edge movement of 11r can be prevented.

In addition, as the circuit is operated by one clock pulse, the jitter values at the rising edge and the falling edge of the recording signal are provided, thereby preventing deterioration of signal characteristics.

The present invention is not limited to the above embodiment, and its use and improvement are possible at the level of those skilled in the art.

As described above, according to the method and apparatus for reproducing a recording signal of an optical disc according to the present invention, it is possible to fundamentally prevent edge movement and jitter without applying an equalizer.

Claims (16)

Converting the reflected beam into an electrical signal while irradiating the optical disk with a predetermined amount of beam; Amplifying the electrical signal with a predetermined degree of amplification; Converting the amplified signal into a digital signal; Obtaining a rising edge pulse and a falling edge pulse of the digital signal; Obtaining a pulse width of the digital signal; And outputting the falling edge pulse at the time when the rising edge pulse is adjusted according to a substantial time in the pulse width after outputting the rising edge pulse. The method of claim 1, wherein the outputting of the falling edge pulse comprises outputting the rising edge pulse and then applying the stepwise time difference to the falling edge pulse to output the falling edge pulse according to the pulse width of the digital signal. And a recording signal reproduction method for an optical disc. The recording signal reproducing method of claim 2, wherein the falling edge pulse to which the parallax is applied is a falling edge pulse that is relatively delayed when the pulse width is relatively short. 3. The recording signal reproduction method of an optical disc according to claim 2, wherein the falling edge pulse to which the parallax is applied is a falling edge pulse which is not relatively delayed if the pulse width is within a predetermined reference range. 3. The recording signal reproducing method of claim 2, wherein the falling edge pulse to which the parallax is applied is a falling edge pulse that has already been stored and is relatively advanced if the pulse width is relatively long. A beam irradiator for irradiating a predetermined amount of beam onto the optical disc; A light detector for converting the beam reflected from the optical disk into an electrical signal; An amplifier for amplifying the electrical signal with a predetermined amplification degree; A comparator for converting the amplified signal into a digital signal; An edge pulse generator for obtaining a rising edge pulse and a falling edge pulse of the digital signal; And a timing decision part for outputting the falling edge pulse at the time when the rising edge pulse is output and then adjusted according to the time corresponding to the pulse width. Device. The method of claim 6, wherein the timing decision part outputs the rising edge pulse and then applies the stepwise time difference to the falling edge pulse, thereby applying the falling edge pulse according to the pulse width of the digital signal. And a recording signal reproducing apparatus for an optical disc, characterized in that for outputting. 8. The recording signal reproducing apparatus of claim 7, wherein the falling edge pulse to which the parallax is applied is a falling edge pulse which is relatively delayed if the pulse width is relatively short. 10. The recording signal reproducing apparatus of claim 7, wherein the falling edge pulse to which the parallax is applied is a falling edge pulse which is not relatively delayed if the pulse width is within a predetermined reference range. 8. The recording signal reproducing apparatus of claim 7, wherein the falling edge pulse to which the parallax is applied is a falling edge pulse that is already stored and relatively earlier if the pulse width is relatively long. The apparatus of claim 6, wherein the timing decision part comprises: an RS flip-flop for generating an original waveform for the rising edge and the falling edge pulses; A counter unit for counting the time when the output of the RS flip-flop is in a logic '1' state; A first gate circuit unit combining the outputs of the counter unit to generate sequential pulses for each bit period of the corresponding write data; A pattern detector for detecting a VFO (Variable Frequency Oscillator) pattern for rising and falling edge pulses; A latch unit for outputting a corresponding pulse among the sequential pulses when the pattern is detected; A falling edge pulse storage for sequentially storing falling edge pulses; And a second gate circuit portion generating a rising edge pulse and generating a falling edge pulse stored according to an output pulse of the latch portion. 12. The recording signal reproducing apparatus of claim 11, wherein the falling edge pulse storage unit has a plurality of D flip-flops connected in series. 12. The recording signal reproducing apparatus of claim 11, wherein the pattern detector enables the latch unit at the time when the falling edge pulse is generated. 13. The apparatus of claim 12, wherein the second gate circuit unit combines each output signal of the D flip-flops and each output signal of the latch unit. 7. The recording signal reproducing apparatus for an optical disc according to claim 6, wherein the optical disc is a magneto-optical disc. 7. The recording signal reproducing apparatus for an optical disc according to claim 6, wherein said optical disc is a compact disc.