KR19980039973A - Playback device of optical disc system - Google Patents

Abstract

The present invention relates to an apparatus for reproducing an optical disc system. The present invention relates to a reproducing apparatus of an optical disc system. A device is made possible.

Description

Playback device of optical disc system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproduction apparatus capable of correcting an error generated when converting an RF (Radio Frequency) signal read from a bad optical disc into a pulse wave, in particular.

In general, optical discs are CD-only CDs, CD-ROMs, video discs, etc., which can be read only by the user. Information can be recorded once, and the recorded information can be read several times, but cannot be erased or rewritten. It can be divided into a recording type and an erased rewrite type that can repeatedly record, erase, and reproduce information.

Play-only type CD is already replacing the existing LP record board in the sound industry, CD-ROM which is a medium that can be searched when necessary by recording a large amount of information that needs to be widely spread such as encyclopedia, and recently in Korea Video discs and the like, which are rapidly expanding, have already been put into practical use and are in the dissemination stage. Additional recordable optical discs can be used for hospitals and large documents that need to store information such as X-rays, NMR-CTs, ultrasound tomography, and patient care cards. It is used for necessary public offices and mineral veins such as mines and oil fields.

The erasing rewritable optical disc has a magneto-optical type and a phase change type. The phase change type records using crystalline / amorphous reversible changes in the process of heating and cooling the micro part of the medium using a laser, and the information is reflected by the difference in reflectance between the two phases. I am using a method to read it.

FIG. 1 is a block diagram of a preamplification apparatus for pre-amplifying a radio frequency (RF) signal read out from an optical disc, and performing waveform processing among optical disc systems for driving such an optical disc.

First, the signals recorded on the optical disc 100 are detected by the photodetector 110. Since the signals detected by the optical disc are generally divided into two systems for the focusing servo, each signal is converted into a current / voltage. The adder 120 converts the signal into one system.

At this time, the output signal of the adder 120 is an eye pattern waveform, and the waveform of the eye pattern causes an error in the detection of the pulse because interference between adjacent waveforms occurs. Accordingly, the waveform equalizer 130 waveform-equalizes the output of the adder 120 to minimize the interference between codes and to narrow the band. The RF output of the waveform equalization unit 130 is provided to a data slice device, and the data slice unit 140 converts the waveform equalized signal into a square wave pulse and converts it into a square wave pulse. (Not shown) to demodulate the EFM.

FIG. 2 shows a detailed configuration diagram of the data slice unit in the preamplifier as described above.

In FIG. 2, the data slicer compares an RF signal provided from the waveform equalizer 140 with a reference signal to generate a square wave, an inverter 142 for inverting the output of the comparator 141, and an inverter ( An inverting unit 143 for inverting the output of the 142 again, an integrator 144 for integrating the output of the inverting unit 143, a buffer 145 for temporarily outputting the output of the integrator 144, and a buffer And an amplifier 146 that amplifies the output of 145 and provides it as a reference signal of the comparator 141.

At this time, the integrator 144 is connected to the output terminal of the inverting unit 143, one end of the resistor (R1), the other end of the resistor (R1) is connected and the other end is the grounded capacitor (C1), the other end of the resistor (R1) One end is connected and the other end is composed of a resistor (R2) connected to the digital signal processing device, one end is connected to the other end of the resistor (R2) and the other end is a grounded capacitor (C2).

A detailed operation description of the data slice unit configured as described above will be described with reference to FIG. 3.

In FIG. 2, when the photodetection signal read from the normal optical disk passes through the adder 120 and the waveform equalizer 130, an RF signal as shown in FIG. 3A is obtained.

Accordingly, when the comparator 141 of the data slicer 140 receives the RF signal such as A shown in FIG. 3A from the waveform equalizer 130, the comparator 141 compares the reference signal as shown in FIG. If the output signal is smaller than the reference signal, a low signal is output to generate a square wave pulse as shown in FIG. 3B.

The square wave pulses output from the comparator 141 are delayed by the inverting units 142 and 143 and then provided to the integrator 144. The integrator 144 integrates and outputs the output of the inverting unit 143.

The output of this integrator 144 is amplified by amplifier 136 via buffer 135 and provided to the reference signal of comparator 131 (B in FIG. 3A). In this case, it is well known that the reference signal of the comparator 131 substantially determines the time constant of the integrator 144, that is, its shape is determined by the resistors R1 and R2 and the capacitors C1 and C2.

As described above, when the optical disc is a normal disc, no problem occurs in the signal output from the data slice unit.

However, when the optical disc is defective, when the optical detection signal read out from the optical disc passes through the adder 120 and the waveform equalizer 130, it is lower than the average low level as shown in the waveform level of the T1 and T2 sections of FIG. Often high RF signals are generated.

Therefore, when the RF signal provided to the data slicer 140 by the waveform equalizer 130 is equal to C of FIG. 3C, the output of the integrator 144 may be equal to D of FIG. 3C. That is, when the waveform level of the sections T1 and T2 in C of FIG. 3C is higher than the average low level of the RF signal, the output of the integrator 144 may be changed as shown in D of FIG. 3C.

Therefore, when the RF signal provided from the waveform equalizer 130 to the data slice 140 is equal to C of FIG. 3C, the output of the comparator 141 is equal to FIG. 3D. Here, when comparing the z section of FIG. 3B and the z section of FIG. 3D, it can be seen that the output of the comparator 141 is changed.

As described above, when the optical disc being reproduced is a bad disc, a square wave signal output from the data slice unit is changed, resulting in an error. In severe cases, the EFM demodulation is not performed in the digital signal processing apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a reproducing apparatus capable of preventing a reproducing error by varying the time constant of the integrator described above when reproducing a bad disc.

The present invention provides a reproducing apparatus of an optical disc system for reproducing an RF signal read from an optical disc in order to achieve the above object: A data slice for converting an RF signal read out from the optical disc into a square wave pulse by shaping a waveform based on a predetermined time constant. part; A digital signal processing unit for performing EFM demodulation of the data slice unit and performing error detection and error correction, and outputting a signal indicating the error if the error is not corrected; A time constant converter for varying the time constant of the data slice unit; And a controller for controlling the time constant converting unit so that a time constant is variable when a signal indicating that the error correction is not provided from the digital signal processing unit is provided.

1 is a block diagram showing a typical configuration of a preamplification device of an optical disk system.

FIG. 2 is a detailed configuration diagram of a data slice unit in the preamplifier of FIG. 1. FIG.

3 is a waveform diagram of each part of FIG. 2.

4 is a detailed block diagram of a playback apparatus according to a preferred embodiment of the present invention.

Fig. 5 is a waveform diagram of each part of the playback apparatus according to the preferred embodiment of the present invention.

<Description of the code | symbol about the principal part of drawing>

140: data slice unit 210: digital signal processing unit

220: time constant conversion unit 230: control unit

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

4 shows a playback apparatus according to a preferred embodiment of the present invention.

In FIG. 4, the reproducing apparatus according to the exemplary embodiment of the present invention may further include a component that can detect an error of data and eliminate the error in the data slice of FIG. 2.

Therefore, in FIG. 4, the same constituent members performing the same functions as those of FIG. 2 are denoted by the same reference numerals for easy understanding.

In FIG. 4, the reproducing apparatus according to the preferred embodiment of the present invention performs EFM demodulation of the data slice unit 140 and the data slice unit 140, performs error detection and error correction, and indicates that the error is not corrected. The digital signal processor 210 for outputting the C2P0 signal, the time constant converter 220 for converting the time constant of the integrator 144 of the data slicer 140, and the time constant converter 220 if the C2P0 signal is provided. The controller 230 is configured to control the time constant of the integrator 144 to be converted.

At this time, the time constant conversion unit 220 is a capacitor (C3), one end of which is connected to one end of the condenser (C1), one end of the condenser (C4), one end is connected to one end of the condenser (C2), the other end of the collector (C3) The base end is connected to the control port of the control unit 230, the emitter end is connected to the other end of the grounded NPN transistor TR1, condenser C4, and the base end is connected to the control port of the control unit 230. The emitter stage is composed of a grounded NPN transistor TR2.

A description of the operation of the playback apparatus configured as described above is given below with reference to FIG.

Normally, the digital signal processing unit 210 performs EFM demodulation on the output of the data slice unit 140 and performs error detection and error correction. The output of the data slice unit 140 may be the same as E of FIG. In this case, error correction cannot be performed.

When the error correction is not performed as described above, the digital signal processor 210 provides the control unit 230 with a C2P0 signal indicating this. When the C2P0 signal is provided from the digital signal processor 210, the controller 230 recognizes that the disc currently being played is in a bad state, and then turns on either the NPN transistor TR1 or the NPN transistor TR2, or The NPN transistor TR1 and the NPN transistor TR2 are turned on at the same time.

If NPN transistor TR1 is on, current will flow in capacitor C3. If NPN transistor TR2 is on, current will flow in capacitor C4. NPN transistor TR1 and NPN transistor TR2 are on at once. In this case, current will flow through the two capacitors (C3, C4) simultaneously.

Thus, the time constant of integrator 144 will be converted. When the time constant of the integrator 144 is converted, the reference signal provided from the amplifier 146 to the comparator 141 may be the same as F of FIG. 5A. Therefore, the output of the comparator 146 will be properly waveform-shaped as shown in Figure 5b.

At this time, when the NPN transistor TR1 and the NPN transistor TR2 are turned off, when only the NPN transistor TR1 is turned on, when only the NPN transistor TR2 is turned on, and when the NPN transistor TR1 and the NPN transistor TR2 are turned on. Is turned on all at once, the time constant of each integrator 144 will be different.

Accordingly, the controller 230 performs the digital signal processing unit 210 during normal operation, that is, while the NPN transistor TR1 and the NPN transistor TR2 are turned off and the data slice unit 140 is operated by the first time constant corresponding thereto. When the C2P0 signal is provided from the above, the above-mentioned three cases, namely, the second time constant when only the NPN transistor TR1 is turned on, the third time constant when only the NPN transistor TR2 is turned on, and the NPN transistor TR1 and NPN transistor The time constant conversion unit 220 is controlled to have any one time constant value among the fourth time constants when TR2 is turned on all at once. Then, even though the time constant of the integrator 144 is converted into any one of the second, third and fourth time constants, if the C2P0 signal is provided from the digital signal processor 210, the process of converting the time constant into another time constant is repeated. This allows the data on the optical disc to be played back by the most appropriate time constant.

For example, when the C2P0 signal is provided from the digital signal processor 210 while the data slice unit 140 operates as the first time constant, the controller 230 may convert the time constant of the integrator 144 into the second time constant. After waiting for the output of the digital signal processor 210 and the C2P0 signal is provided from the digital signal processor 210 even after the time constant of the integrator 144 is converted into the second time constant, the time constant of the integrator 144 is removed. After converting to the third time constant or the fourth time constant, it is again searched whether the C2P0 signal is provided from the digital signal processor 210, and even after the time constant of the integrator 144 is converted to, for example, the fourth time constant, the digital signal processor When the C2P0 signal is provided from 210, the data of the optical disc is reproduced by the most appropriate time constant through the repetition of the process of converting the time constant of the integrator 144 into the third time constant.

As described above, the present invention has an effect of preventing a playback error caused by a defective disk by playing back by changing the time constant of the integrator when the defective disk is played.

Claims (1)

A reproduction apparatus of an optical disc system for reproducing an RF signal read out from an optical disc: A data slice unit 140 for converting the RF signal read out from the optical disk into a square wave pulse by shaping a waveform based on a predetermined time constant; A digital signal processor (210) for performing EFM demodulation of the output of the data slice unit (140) and performing error detection and error correction, and outputting a signal indicating the error correction if it is not corrected; A time constant converter 220 for varying the time constant of the data slicer 140; And a control unit (230) for controlling the time constant conversion unit (220) so that a time constant is variable when a signal indicating that the error correction is not provided from the digital signal processing unit (210) is provided.