KR0120530B1 - Recording and reproducing apparatus of optical disk - Google Patents

Abstract

A recording and reproducing apparatus of an optical disc is disclosed. In the apparatus, a modulator(10) encodes an input sound information into a tri-state data. A laser light emitting output control section(20) differently projects laser amount according to a level of an output signal from the modulator(10) and controls a melting rate of an optical disc. An pick-up device pick ups reflecting amount of the emitted laser. A waveform shaping section(60) converts a high frequency signal outputted from the pick-up device into a square wave signal. A decoder(70) decodes an output signal from the waveform shaping section(60).

Description

Optical disc recording and playback device

1 is a block diagram of an optical disc recording and reproducing apparatus according to the present invention.

FIG. 2 is a detailed circuit diagram of the laser emission output control unit and pickup means employed in FIG.

3 is a view for explaining the laser light output in the recording and playback according to FIG.

4A is a sectional view of a disk used in the present invention.

4b is a cross-sectional view of the disc recorded by the pickup means according to FIG.

5 is a detailed circuit diagram of the waveform shaping unit employed in FIG.

6 is a waveform diagram of a signal output from the high frequency amplification unit employed in FIG.

* Explanation of symbols for main parts of the drawings

10: modulator 20: laser emission output control unit

30: pickup means 40: servo unit

41: spindle motor 50: high frequency amplifier

60: waveform shaping section 70: demodulation section

The present invention relates to an apparatus for recording and reproducing an optical disc, and more particularly, to an apparatus capable of recording and reproducing ternary data with different laser light output.

In general, in the optical disk device, the recording density of the compact disk is about 500600 Mbytes per side on the basis of 5.25 inches, so that it is recorded at a considerably higher density than a floppy disk or a hard disk. However, in view of the increasing trend of the amount of data to be processed, there is a need for an apparatus capable of recording and reproducing more dense data. Due to these demands, short wavelength laser diodes having wavelengths of about 800 mm have been developed to achieve high density of data in optical disk devices.

However, the conventional apparatus for recording and reproducing binary data on a disc while maintaining a constant laser light output has a limitation in recording data at a high density.

Accordingly, an object of the present invention is to provide an optical disc recording and reproducing apparatus capable of firing a light emission output of a short wavelength laser in a predetermined step to melt the medium of the disc to record and reproduce the acoustic information as ternary data.

In order to achieve the above object, the present invention is to change the laser emission output in accordance with the level of the signal output from the modulation means for encoding the incoming acoustic information into the ternary data, the melting of the medium layer of the disk Laser emission output control means for controlling the degree, pickup means for picking up the reflected amount of the projected laser, wavelength shaping means for converting a high frequency signal output from the pickup means into a square wave signal, and the waveform shaping means And demodulation means for decoding the output signal.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the recording and reproducing apparatus of the optical disk in the present invention.

1 is a block diagram showing the configuration of an optical disc recording and reproducing apparatus according to the present invention.

In FIG. 1, a terminal 11 for introducing acoustic information from a signal input source (not shown) is connected to a modulator 10, and the output end of the modulator 10 is connected to a laser emission output control unit 20. In FIG. Is connected to the input terminal.

The input terminal of the pickup means 30 is connected to the output terminal of the laser emission output control unit 20, and the output terminal is connected to the input terminal of the servo unit 40 and the high frequency amplification unit 50.

The input end of the waveform shaping section 60 is connected to the output end of the high frequency amplification section 50, the output end is connected to the input end of the demodulation section 70, and the output end 71 of the demodulation section 7 is connected to the digital reproduction processing circuit. (Not shown).

Subsequently, the operation of FIG. 1 will be described. In the modulator 10, A / D conversion of an acoustic signal introduced from a signal input source (not shown) is performed, and then encoded into ternary data composed of 0, 1, and 2. do.

The laser emission output control unit 20 converts the ternary data into an analog voltage level and controls the laser emission output to be projected onto the disc in three stages.

The servo unit 40 maintains a constant distance between the lens of the pickup means 30 and the signal surface of the disk CD, the tracking servo for controlling the tracking of the track, and the linear velocity of the disk CD. It is composed of a rotary servo to control to rotate, the rotary servo controls the drive of the spindle motor (41).

The pickup means 30 picks up the reflection amount of the laser fired on the disc and outputs a high frequency signal to the high frequency amplifier 50. The waveform shaping unit 60 converts the amplified high frequency signal output from the high frequency amplifying unit 50 into a square wave signal by comparing with a reference value.

The demodulation section 70 decodes and demodulates the output signal of the waveform shaping section 60, and outputs it to the digital signal processing circuit for performing error correction.

2 is a detailed circuit diagram of the laser emission output control section and the pickup means employed in FIG.

In FIG. 2, the second inversion connected to the input terminal 22 of the D / A converter 21 to the output terminal of the modulator 10 shown in FIG. 1, and the output terminal is connected to the first inverting amplifier OP1. The inverting terminal of the amplifier OP2 is connected.

The inverting terminal of the third operational amplifier OP3 connected to the resistors R5 and R6 for determining the amplification ratio is connected to the output terminal of the second inverting amplifier OP2, and the output terminal is connected to the base terminal of the transistor TR1. do.

The emitter terminal of the transistor TR1 is connected to the emitter resistor R7 connected to the base power supply, the collector terminal is connected to the cathode terminal of the laser diode LD, and the anode terminal is supplied to the laser diode LD. Connect to the cathode end of monitor diode (MD).

An anode terminal of the monitor diode MD is connected to an inverting terminal of the first inverting amplifier OP1.

Next, the operation of FIG. 2 will be described with reference to FIGS. 3 to 4. Referring to FIG. 2, in the D / A converter 21 of the laser emission output controller 20, the ternary data (0, 1, 2) output from the modulator 10 shown in FIG. Convert to

The ALPL (Automatic Laser Power Control) circuit for maintaining a constant laser light output during regeneration includes a monitor diode (MD), first to third operational amplifiers (OP1 to OP3), transistor (TR1), laser diode (LD) It is made in Peru.

Generation of the two-stage laser luminous output during recording is carried out by an open loop consisting of a D / A converter 21, a second operational amplifier OP2, a third operational amplifier OP3, a transistor T41, and a laser diode LD. It is.

In this case, the laser emission output during reproducing of Peru is performed by sensing the emission output of the laser diode LD of the pickup means 30 by the monitor diode MD, so that the output of the first inverting amplifier OP1 is negative. Component, and the output of the second inverting amplifier OP2 is a positive (+) component, and the reference of the output of the second inverting amplifier OP2 input to the inverting terminal of the third operational amplifier OP3 and the non-inverting terminal. The difference voltage with the voltage is applied to the base terminal to the second transistor TR1. The first transistor TR1 is in an active region and emits the laser diode LD by the collector current flowing through the transistor TR1.

When describing an open loop capable of generating a two-stage laser emission output during recording, the ternary data output from the modulator 10 is converted to an analog voltage level by the D / A converter 21, and then the second inversion is performed. Summing to the inverting terminal of the amplifier OP2. The output of the second inverting amplifier OP2 is input to the inverting terminal of the third operational amplifier OP3 according to the voltage level of the D / A converter 21 input to the inverting terminal of the second inverting amplifier OP2. The output of the operational amplifier OP3 is amplified by a voltage corresponding to a difference between the output of the second inverting amplifier OP2 and the reference voltage supplied to the non-inverting terminal of the third operational amplifier OP3, and thus the base of the transistor TR1. It is input to the stage to change the light emitting output of the laser diode (LD).

Accordingly, as shown in FIG. 3, when the light emission output level output from the laser light emission output control unit is 0, when the laser light output level is 1 during reproduction, the first recording light emission output level becomes the light emission output level, and light emission occurs. When the output level is 2, the second recording light emission output level is obtained.

4A is a cross-sectional view of a disc used in the recording and reproducing apparatus of the optical disc according to the present invention. According to FIG. 4A, two media A and B are melted at different temperatures and have different reflectances. That is, the disk is laminated with a medium A that melts above a low temperature T1 and a medium B that melts at a higher temperature T2 than T1. There is a hard protective layer on the medium A, B. 4B is a cross-sectional view for explaining a medium state of a disk melted according to the light emission output level of the laser diode output from the laser light emission output control unit.

That is, when the light emission output level is 2, the medium (A) and the medium (B) layers are melted; when the light emission output level is 1, the medium (A) layer is melted; The luminous output does not melt the medium of the disc.

5 is a detailed circuit diagram of the waveform shaping unit employed in FIG.

In Fig. 5, the resistor R8 and the capacitor C1 are constituted by differential circuits, and the output terminals of the differential circuits are connected to non-inverting terminals of the first and second comparators COMP1 and COMP2.

The inverting terminal of the first comparator COMP1 is connected between the resistors R9 and R10 connected in series between the supply power supply terminal V∝ and the base power supply GND, and the output terminal T1 is connected to the supply power supply terminal V. Connect to the flop resistor (R11) connected to i).

The inverting terminal of the second comparator COMP2 is connected between the resistors R11 and R12 connected in series between the supply power supply terminal V∝ and the base power supply GND, and the output terminal T2 is connected to the supply power supply terminal V. Connect to the flop resistor (R14) connected to i).

Next, the operation of FIG. 5 will be described by combining the waveform of FIG.

Referring to FIG. 5, in the waveform shaping unit 60, the signal output from the high frequency amplification unit 50 passes through the signal as having a level a and b according to the melting state of the disk, as shown in FIG. Pass it through.

Resistors R9 and R10 connected to non-inverting terminals of the first and second comparators COMP and COMP2, and outputted to the inverting terminals of the first and second comparators COMP and COMP2. And a reference level at which the voltage division ratio is determined by the values of the resistors R11 and R12. At this time, the reference level of the second comparator COMP2 is the b level shown in FIG. 6, and the reference level of the first comparator COMP1 is the a level shown in FIG. 6. When the output of the differential circuit, that is, the reproduction high frequency signal is greater than each mood level, the output signal high (H) logic signals of the first and second comparators COMP1 and COMP2 are output. The low L logic circuit outputs the output signals of the second comparators COMP1 and COMP2.

Therefore, the demodulator 70 decodes the digital values output from the output terminals T1 and T2 of the first and second comparators COMP1 and COMP2.

As described above, the optical disc recording and reproducing apparatus according to the present invention adjusts the laser light output in three stages, melts the medium layer on the disc, records it in ternary data, and then picks up and reproduces the molten state on the disc to record at high density. And playback.

Claims (3)

In an optical disc system having a disc in which two layers having different melting points are stacked, modulation means for encoding incoming acoustic information into ternary data, and laser amounts vary depending on the level of a signal output from the modulation means. Laser emission output control means for projecting and controlling the degree of melting of the medium of the disk, pickup means for picking up the amount of reflection of the emitted laser, and waveform shaping means for converting a high frequency signal output from the pickup means into a square wave signal; And demodulation means for decoding the signal output from the waveform shaping means. The laser light output control means of claim 1, wherein the laser emission output control means signs a D / A converter for converting data of the modulation means into an analog voltage level, and a voltage level output from the D / A converter. And a current limiting means for controlling the luminous output. The recording and reproducing apparatus according to claim 1, wherein the waveform shaping means includes first and second comparators for comparing the level of the high frequency signal output from the pickup means with a reference level.