KR100243175B1 - Disc reproducer - Google Patents

Abstract

The present invention relates to a disc reproducing apparatus capable of reproducing a signal after correcting a signal level according to an amplitude and a modulation degree of a reproducing signal read from a disc, and detecting the presence or absence of an error in the reproducing signal.

According to the reproduction signal correcting apparatus according to the present invention, a disc having different quality by improving the detection efficiency of the reproduction signal by improving the detection efficiency of the reproduction signal by adjusting the gain by grasping the level of the input signal in advance according to the amplitude and modulation degree of the input reproduction signal in advance. In addition, it has the advantage of lowering the error rate during reproduction of the recording / reproducing system, and also according to the error detecting device of the present invention, a signal that cannot be reproduced by detecting a signal level according to the amplitude and modulation degree of the input reproduction signal is inputted. In this case, there is an advantage that the malfunction of the playback apparatus can be effectively prevented by displaying an error state.

Description

Disc player

1 is a block diagram of a conventional disc recording and reproducing apparatus.

2 is a block diagram of a disc reproducing apparatus according to the present invention.

3 is a flowchart for explaining the operation of the disc reproducing apparatus according to the present invention.

4 is a table of signal levels and modulation degrees associated with FIG.

5 is a waveform diagram of a disc reproducing signal.

<Explanation of symbols for main parts of drawing>

21: regenerative amplifier 24: synchronization circuit

25: Play select switch 26: Error output unit

221: automatic gain control circuit 222: equalizer

223 detection circuit 231 signal level detecting unit

232: correction control unit 233: waveform correction

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc reproducing apparatus for reproducing and outputting data of a disc. In particular, a signal level is corrected according to an amplitude and a modulation degree of a reproduced signal read from a disc, and then reproduced. Disc playback apparatus that can be.

Digital Video Disk Recorder (DVDR), which converts video and audio signals to digital data, records and plays them on a magneto-optical disk, has different playback efficiency depending on the amplitude and modulation of the playback data. The amplitude and modulation degree of the playback data vary depending on the type of.

A method and apparatus for controlling the automatic gain control circuit of an optical disc system in accordance with the amplitude of the reproduction data are described in US Patent No. 5,124,967 as follows. The difference in amplitude magnitude between the reproduction signal from the preformatted area of the optical disc and the reproduction signal from the recording area of the user data is obtained. When the amplitude difference is larger than the predetermined value, the first gain value set for the information in the tightly formatted area is used as the gain value of the automatic gain control circuit, so that gain control of the reproduction signal is performed. On the other hand, when the amplitude difference is smaller than the predetermined value, the second gain value set for the user data is used. Therefore, it is possible to prevent a situation in which residual signals of noise or indelible user data are incorrectly recognized as original reproduction signals. In addition, it is possible to accurately discriminate whether or not data is recorded in the recording area of the user data.

FIG. 5 generally shows the reproduction signal waveform of a magneto-optical disc drive or a DVDR, IL denotes the amplitude of the reproduction waveform of the longest period, IH denotes the amplitude of the reproduction waveform of the shortest period, and modulation degree is expressed by the following equation. .

Since the size of IL and IH may vary depending on the type of disc, the IL, IH, and modulation degree of the reproduction signal are very important parameters in consideration of the compatibility of the disc in the disc reproducing apparatus.

In particular, the reproduction-only system and the recordable recording / reproducing system have many differences in amplitude and modulation degree of the reproduction signal. The read-only system reproduces the signal recorded on the disc in advance, so that a clear signal can be obtained at the time of reproducing, but the system capable of recording and reproducing includes the basic noise of the system such as laser noise, disc noise, circuit noise and optical noise. Since the signal is recorded, the amplitude actually recorded should be larger than that of the read only system.

In the conventional automatic gain control circuit, the gain variation must be large because it must be varied in a considerably large range according to the amplitude or modulation degree of the reproduction signal, and the error probability increases to generate an optimal reproduction signal. In addition, there is a problem in that the playback apparatus does not properly cope with the playback even when an error condition in which a signal that cannot be reproduced is input to the automatic gain control circuit occurs for some reason in the playback apparatus.

Accordingly, it is an object of the present invention to provide a disc reproducing apparatus including a reproducing signal correcting device that detects a signal level in advance and adjusts a gain step by step in accordance with an amplitude and a modulation degree of an input reproducing signal.

Another object of the present invention is to provide a disc reproducing apparatus including an error detecting device for displaying an error state when a signal that is difficult to reproduce by detecting a signal level in advance according to an amplitude and a modulation degree of an input reproducing signal is input.

A reproduction signal correction apparatus of a disc reproducing apparatus according to the present invention for achieving the above object comprises: a reproducing amplifier for amplifying an electric signal generated by reading recording information of a disc; An automatic gain control circuit for adjusting the amplified signal to a constant signal level to generate a reproduction signal; And an equalizer for restoring the reproduction signal to an original recording signal, the disc reproduction apparatus comprising: detecting a signal amplitude of a reproduction signal of the automatic gain control circuit and generating a proportional signal according to the detected signal amplitude; Signal level detecting means; Control means for determining a modulation degree of a reproduction signal based on the proportional signal and generating information on a reproduction signal level according to the modulation degree; And waveform correction means for correcting the reproduction signal to a signal having a predetermined level according to the information, and returning the corrected signal to the automatic gain control circuit so that the signal level has a predetermined modulation degree in accordance with the modulation degree of the reproduction signal. After the level correction, the gain can be adjusted again by returning to the automatic gain control circuit.

An error detecting apparatus for a disc reproducing apparatus according to the present invention for achieving the above another object comprises: a reproducing amplifier for amplifying an electric signal generated by reading record information of a disc; And an automatic gain control circuit for adjusting the amplified playback signal to a predetermined signal level, the disk playback device comprising: detecting a signal amplitude of a playback signal of the automatic gain control circuit, and proportional to the detected signal amplitude; Signal level detection means for generating a; Control means for determining a modulation degree of a reproduction signal based on the proportional signal, and generating information indicating that a reproduction error state is generated if the modulation degree is smaller than a predetermined value; And an error output means for indicating an error state according to the information, wherein an error state can be displayed when a reproduction signal inappropriate to be reproduced according to the modulation degree of the reproduction signal is input.

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

1 is a block diagram of a conventional disc recording apparatus and playback apparatus.

The disc recording device includes an analog-to-digital converter 101, a DSP encoder 102, a recording compensator 103, and an optical power control 104. And record the input video signal and audio signal on the disc 105.

The analog-to-digital converter 101 converts a video signal and an audio signal, which are analog signals to be recorded, into a digital signal, and the DSP encoder 102 comprises input data consisting of "1" and "0" of binary information. The bit string is converted into a recording code string according to a modulation method.

The recording compensator 103 performs write pulse compensation to improve the recording density characteristics and to reduce the waveform interference during reproduction. The optical power control unit 104 converts the corrected write pulses into optical signals and records them on the optical disc (DISC) 105.

The disc reproducing apparatus includes a photo detector 111, a reproducing amplifier 112, a reproducing equalizer 113, a synchronizing circuit 114, a DSP decoder 115 and a digital-analog converter ( DAC) 116 reproduces the data read from the disk 105 as original video signals and audio signals and outputs them.

The photodetector 111 converts the optical signal reflected from the optical disk 105 into a current signal, the reproduction amplifier 112 amplifies the reproduction signal converted into the current signal, and the reproduction equalizing unit 113 distortion of the reproduction signal. Distortion and noise are removed and waveform shaping is performed, and the synchronizing circuit 114 restores the synchronizing signal and the reproducing data from the reproducing signal.

The DSP decoder 115 detects whether or not there is a reproduction pulse signal of light in a time zone determined by using the synchronization signal generated from the synchronization circuit unit 115, that is, in a detection window, and detects the detected code string. Is demodulated into a data bit string, and the digital-analog converter 116 converts the demodulated data bit string into an analog video signal and an audio signal and finally outputs it.

2 is a block diagram of a disc reproducing apparatus including a reproducing signal correcting apparatus and an error detecting apparatus according to the present invention. The conventional reproducing equalizing unit 22 again has an automatic gain control circuit 221; It may be divided into an equalizer 222 and a detection circuit 223.

The automatic gain control circuit 221 automatically adjusts the gain of a reproduction signal of a disc having a different output level according to a difference in the radius or reflectance of the disc and adjusts the signal level to be constant. The equalizer 222 removes errors such as unnecessary noise and interference with adjacent waveforms in the gain-adjusted reproduction signal and restores the same as the original recording signal. The detection circuit 223 demodulates the modulated and recorded reproduction signal.

The reproduction signal correction apparatus 23 according to the present invention includes a signal level detection unit 231, a correction control unit 232, and a waveform correction unit 233.

The signal level detecting unit 231 generates the proportional signal PA1 according to the amplitude of the reproduction signal 220 output from the automatic gain control circuit 221. The correction controller 232 calculates a modulation degree of the reproduction signal according to the proportional signal PA1 of the signal level detection unit 231, and generates a control signal PB for classifying the reproduction signal level according to the calculated modulation degree. Output to the government 233. The waveform correction unit 233 corrects the level of the reproduction signal according to the control signal PB for the signal level of the correction control unit 232 and returns it back to the automatic gain control circuit 221 (230). The returned correction signal 230 adjusts the gain in the automatic gain control circuit 221 and outputs it to the equalizer 222 (240).

The regeneration selection switch 25 is an input device for informing the correction control unit 232 whether the system is to perform a regeneration operation through the input port PD0. The input port of the PD0 is initially in a high state, and then the switch is pressed. It goes low to ground, indicating that the system is in playback mode. The input signal of the PD0 may be a control signal generated according to a current system operation state in the disk system controller.

In the regeneration mode, the signal level detecting unit 231 inputs the output reproducing signal 220 of the automatic gain control circuit 221 to generate a proportional signal proportional to the signal amplitude for a predetermined range of voltages, and the correction control unit 232 calculates the modulation level of the reproduction signal according to the proportional signal inputted to the input terminal PA1 to determine the signal level, and outputs a control signal according to the signal level to the waveform correction unit 233 through the output ports PB0 to PB1. .

For example, the signal level detector 231 may generate a proportional signal with an analog voltage of 0 V to 5 V with respect to the amplitude of the input signal, and the correction controller 232 may have 8 bits in 256 steps with respect to the proportional voltage signal. Signal level can be distinguished by converting into digital data.

Among the microcomputers currently used, some analog signals can be detected not only with 256 steps but also with 8 to 16 bits of digital signals.

The reference for dividing the signal level by the degree of modulation in the correction control unit 23 is a normal signal level at which the playback apparatus can normally reproduce a signal, a correction signal level requiring level correction for the playback signal, and a playback apparatus normally reproduces the signal. The error signal level can not be divided.

In this embodiment, the operation of the reproduction signal correction apparatus according to the present invention will be described by dividing the reproduction signal level according to the modulation degree into four stages of A, B, C, and D. FIG. Step A is divided into more than 70% modulation, B is less than 70% at 50% modulation, C is less than 50% at 30% modulation, and D is less than 30% modulation. Step A is defined as the normal playback signal level, steps B and C are the playback signal levels that require correction, and step D is the error signal level at which playback signals cannot be played back normally.

The waveform correction unit 233 corrects the waveform so that the current reproduction signal becomes a normal reproduction signal level according to the information on the signal level of the correction control unit 232 input to PB0 to PB1 and outputs it to the automatic gain control circuit 221. (230).

The waveform correction unit 233 outputs the current reproduction signal as it is without waveform correction since reproduction is possible without waveform correction when the reproduction signal level is A level. In the case where the reproduction signal level is at the B stage or the C stage, since it is difficult to reproduce the original signal, waveforms are corrected for each stage so as to be the same as the A stage which is the reproducible signal level.

If the correction control unit 232 further subdivides the level of the correction signal, and the waveform correction unit 233 can correct the level according to each step, it is possible to more precisely control the level correction for the playback signal. have

The relationship between the error detection device and the reproduction signal level according to the present invention is as follows. When the size of the playback signal 220 inputted to the signal level detection unit 231 is too small to be an error signal level at which the disc playback device cannot normally play back the playback signal, that is, at the D stage where the playback signal cannot be read normally. The correction control unit 232 informs the error output unit 26 of the error state through the output port PC1, and the error output unit 26 displays the error state to the user, thereby operating as an error detection device.

When an error detection device detects and displays an error, an unrecorded disc is operated or a signal cannot be played back because the disc or playback device does not operate normally. The user takes appropriate measures according to the displayed error conditions. Allow the system to operate normally.

3 is a flowchart for explaining the operation of the disc reproducing apparatus according to the present invention, and FIG. 4 is a table showing the relationship between the level of the reproduction signal and the modulation degree.

Upon detecting the level of the reproduction signal 31, the signal level according to the modulation degree is determined 32 based on the reference shown in FIG. If the signal level is A stage (33), the reproduced signal is output as it is without correction, and if the signal level is B stage 34 or C stage 35, the reproduced signal is corrected (36) according to the correction size corresponding to that stage. If the signal level is the step D of the error signal level, an error signal is output (37).

In the embodiment of the present invention, the waveform correction and error detection are controlled by dividing the level of the playback signal into four levels of A, B, C, and D. However, in the application of the present invention, the playback signal level can be further divided and controlled. have.

As described above, according to the reproduction signal correcting apparatus of the present invention, the detection efficiency of the reproduction signal is improved by grasping the level of the input signal in advance according to the amplitude and the degree of modulation of the input reproduction signal and dividing it step by step to adjust the gain. This has the advantage of contributing to the compatibility of discs of different qualities and, in particular, lowering the error rate during playback of a recording / playback system.

In addition, the error detecting apparatus of the present invention can effectively prevent a malfunction of the reproducing apparatus by displaying an error state when a non-reproducing signal is input by detecting the reproducing signal level according to the amplitude and modulation degree of the input reproducing signal. There is this.

Claims (6)

A reproduction amplifier for amplifying the electric signal generated by reading the record information of the disc; An automatic gain control circuit for adjusting the amplified signal to a constant signal level to generate a reproduction signal; And an equalizer for restoring the reproduction signal to an original recording signal, the disc reproduction apparatus comprising: detecting a signal amplitude of a reproduction signal of the automatic gain control circuit and generating a proportional signal according to the detected signal amplitude; Signal level detecting means; Control means for determining a modulation degree of a reproduction signal based on the proportional signal, and generating information on the reproduction signal level by dividing at least a normal signal level requiring no signal correction and a correction signal level requiring signal correction according to the modulation degree; And waveform correction means for correcting a playback signal according to the information to have a modulation degree corresponding to the normal signal level, and returning the corrected signal to the automatic gain control circuit. Device. The reproduction signal correction apparatus of claim 1, wherein the normal signal level is a signal level at which a modulation degree of the reproduction signal is greater than 70%. The apparatus of claim 1, wherein the correction signal level is divided into a predetermined number of steps. The method of claim 1, wherein the signal level detecting means generates a proportional signal as an analog signal proportional to the amplitude of the reproduction signal, and the control means converts the proportional signal into a digital signal of a predetermined bit to improve the modulation degree of the reproduction signal. And a reproducing signal correcting device of the disc reproducing apparatus. 2. The apparatus of claim 1, further comprising: error control means for determining a modulation degree of a reproduction signal based on the proportional signal, and generating information indicating that a reproduction error state is generated if the modulation degree is smaller than a predetermined value; And error output means for indicating an error state according to the information. 6. The error detection apparatus of the disc reproducing apparatus as set forth in claim 5, wherein the predetermined value of said error control means is 30% modulation degree.