KR0183039B1 - Laser power decision circuit and method for optical record/reproducing apparatus - Google Patents

Abstract

The present invention relates to an optical recording and reproducing apparatus, and an object thereof is to provide a circuit and a method for determining an optimum laser power. To this end, in the present invention, the reference laser power is read to calculate different levels of test laser power, and the ID data and the EFM test pattern for identifying each of the calculated test laser powers are assigned to the ATIP frame unit in a specific partition with the corresponding test laser power. Record as. Thereafter, when the DC component of the reproduced RF signal converted into digital data during the partition reproduction has a value within the asymmetric allowable range, the laser power indicated by the input ID data corresponding thereto is determined as the optimal laser power, and then the determined laser power is determined. Record the data with

Description

Laser Power Determination Circuit and Method of Optical Recorder

1 is a block diagram of an optical recording and reproducing apparatus to which a laser power determining circuit according to an embodiment of the present invention is connected.

2 is a flow chart of the microcomputer 5 for determining an optimum laser power according to an embodiment of the present invention.

3A and 3B of FIG. 3 are exemplary diagrams of output signal waveforms of the AC coupling unit 13 and symmetrical and asymmetric waveforms with respect to the input signal.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing apparatus capable of recording information on a recording medium such as a compact disc, and more particularly, to a laser power determining circuit and method capable of optimally determining laser power during recording. will be.

Typically, in an additional (recordable form) optical disk system, a pit is formed on the recordable disk surface to record information. The pit is formed by laser light emitted from the optical pickup, and an elliptical pit is formed on the disk surface by laser power modulation of the input signal. If the laser power used to form the pit is not appropriate, an error occurs during data reproduction, so the laser power becomes a very important factor. Therefore, in the standard of recordable optical disc system, the regulation is defined.

In view of the factors influencing the formation of pits, the laser power for forming pits varies depending on the sensitivity of the surface of the disc in the case of a laser having the same wavelength as a factor caused by the disc. The optimum laser power varies depending on the type temperature of the laser used by the recording device itself.

On the other hand, according to the definition of the recordable recording system (ORANGE BOOK PART II), the recommended laser power of the disc to be recorded (RECOMMENDED OPTIMUM LASER POWER) is provided as an ATIP code in the lead in area. Hereinafter, this will be referred to as a reference laser power (REFERENCE LASER POWER: Pref).

However, in general recordable optical disc system, since standard laser power is uniformly applied without considering the state of the system and the surrounding environment, there is an error in reproducing data due to the change of the state of the system or the inability to adapt to the change of the surrounding environment. The probability of occurrence increases.

Accordingly, an object of the present invention is to provide a laser power determining circuit and method for determining the optimal laser power for data recording in a recordable optical recording and reproducing apparatus.

The present invention for achieving the above object is an optical disk, an optical pickup for recording data on the optical disk surface or to pick up and reproduce the data recorded on the optical disk surface, and RF for amplifying and outputting the RF signal reproduced from the optical pickup An optical recording and reproducing apparatus including an amplifier and a data reproducing section for converting the amplified RF signal into EFM data, converting the converted amplification data into EFM data, and decoding the converted data. Conversion means for converting the digital data into digital data, ID data for identifying the laser power, and an EFM test pattern at different levels of laser power in the test area of the optical disk surface, and at the time of reproducing the test area. When the digital data input from the converting means has a value within the asymmetric allowable range, To determine the laser power for data ID indicating the data input from the reproducing unit to the optimum laser power value is characterized in that it consists of a control unit used in the recording.

Hereinafter, the configuration and operation of a laser power determination circuit according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, the terms and basic principles to be used in the present invention will be briefly described, and the specification of the ORANGE BOOK disclosed provides a power measurement area (PCA) for laser power calibration. The power measurement area (PCA) is divided into a test area for recording / reproducing actual EFM frame data and a count area for quickly and easily knowing how many times the laser power measurement is performed. do. In addition, the disc specification prescribed in the Orange Book is largely defined into five areas as follows.

The first PMA is a program memory area, where recording is performed several times without recording the disc all at once (additional recording). It is an area for recording information about tracks recorded up to that time, and the second LIA is a lead-in area for TOC information. This is an area to record the area and to record when the disc is last recorded.

The third PA is a program area where real information is recorded, and the fourth LOA is a lead out area that marks the end of the disc. Finally, the PCA is a power measurement area as a test calibration area. It is composed of 100 partitions to perform the optimal power measurement (OPTIMUM POWER CALIBRARTION: OPC) 100 times. At this time, one partition has 15 ATIP frames (time of 1 PTIP frame: 1/75 sec). In other words, once one optimal power measurement (OPC) is performed, a test pattern may be recorded in 15 ATIP frames for one partition. Since one ATIP frame corresponds to 98 frames EFM (1/75 sec = 13.3 ms), data for one block can be recorded 15 times. Therefore, when the test pattern is recorded in the test area, the laser power is changed for each of the 15 ATIP frames, recorded, reproduced, and compared to determine the optimal laser power. On the other hand, the count area counts the number of times the OPC is performed so that the partition which is not recorded during the next OPC can be easily identified.

Therefore, in the exemplary embodiment of the present invention, the test pattern is recorded with the laser powers within a predetermined range centered on the reference laser power Pref, and the symmetry of the RF signal is detected when the recorded test pattern is reproduced. The optimal laser power can be determined.

Referring to the configuration according to the embodiment of the present invention, firstly, FIG. 1 shows a block diagram of an optical recording / reproducing apparatus to which the laser power determining circuit 100 according to the embodiment of the present invention is connected. Referring to FIG. 1, an optical disc divided into five regions rotates at a constant speed by driving of the motor 10. The optical pickup 11 optically picks up the data recorded on the detector surface, converts the data into an RF signal which is an electrical signal, and outputs the converted signal. The optical pickup 11 also records, on the disc surface, encoding recording data output from the LPM encoder (Laser Power Modulation Encoder) 16 as laser light output controlled by the laser power controller 15. The LPM encoder 16 encodes and outputs an ID number and an EFM pattern input from the microcomputer 5, respectively. On the other hand, the reproduction signal picked up by the optical pickup 11 is input to the AC coupling unit 13, the servo and the reproduction unit 14 after the level amplification and noise are removed from the RF amplifier 12. The servo and reproducing unit 14 generates drive signals for rotating control of the disk, focusing and tracking control of the optical pickup 11, and outputs the driving signals to the optical pickup 11 and the motor 10, and amplified RF signals. The EFM signal obtained by the waveform equalization process is decoded to reproduce and output pure recording data. The servo and reproduction unit 14 also outputs ID data, which is decoded data of a subqcode, to the microcomputer 5 through the S terminal. The AC coupling unit 13 couples and outputs the amplified RF signal, and the laser power controller 15 is controlled by the microcomputer 5 and outputs an output control signal for adjusting the laser output to the optical pickup 11. Output

On the other hand, the laser power determining circuit 100 is composed of an integrator 1, an amplifier 2, an A / D converter 3, and a microcomputer 5. The integrator 1 integrates and outputs an RF signal (3A1 in FIG. 3) coupled to and output from the AC coupling unit 13 according to a specified RC constant to obtain a signal almost close to the DC component level based on the zero level. 3A 2 degrees). At this time, it is important that the RC constants of the elements R1 and C1 constituting the integrator 1 are selected by a test to detect the asymmetry of the input signal. The amplifier 2 amplifies the output signal of the integrator 1 to a predetermined level, and the amplified signal is converted into digital data by the A / D converter 3 and input to the microcomputer 5. The microcomputer 5 has an internal memory in which a control program for controlling the optical recording and reproducing apparatus according to the embodiment of the present invention is stored. Therefore, the microcomputer 5 controls the overall operations such as data recording and reproducing of the optical recording and reproducing apparatus, laser power determination and the like based on the control program. For example, the microcomputer 5 receives digital data sampled from the A / D converter 3 every 1 ATIP frame period (13.3 ms x 98 EFM frames) together with ID data input from the servo and playback unit 14. After storing the digital data, the asymmetry of the stored digital data is included in the asymmetry allowance (20%) defined in the Red Book specification, and the corresponding laser power is determined as the optimal laser power. If there is a large number of digital data included in the asymmetry allowable range, the laser power with the minimum asymmetry is determined as the optimal laser power.

FIG. 2 is a flowchart illustrating the operation of the microcomputer 5 for determining an optimum laser power according to an embodiment of the present invention, and FIGS. 3 (a) and 3 (b) are outputs of the AC coupling unit 13, respectively. A signal waveform diagram and an example of symmetrical and asymmetric waveforms for an input signal are shown. In FIG. 3A, 3A1 shows a waveform obtained by AC-coupling an RF signal reproduced by the optical pickup 11, and 3A2 shows a waveform that appears when the 3A1 waveform has passed through the integrator 1. In FIG. 3B, 3B1 shows an asymmetric waveform when the test pattern is recorded with a laser power smaller than the optimal laser power, and (d) shows a test pattern with a laser power larger than the optimal laser power. Figure 2 shows another asymmetric waveform that appears in. 3B2 shows waveforms when the test pattern is recorded at the optimal laser power. That is, if the test pattern is recorded with the optimal laser power, the coupled RF signal waveform is symmetrical with respect to the reference level (zero level) as shown in 3B2 of FIG. 3.

Hereinafter, an operation until determining an optimal laser power will be described with reference to FIG. 2.

First, when the system is running, the microcomputer 5 sequentially performs the steps for determining the optimum laser power based on the operation flow shown in FIG. That is, the microcomputer 5 reads the reference laser power Pref recorded in the lead-in area LIA in step A. FIG. The reference laser power Pref is used to define a range of 15 laser powers P for recording the test pattern. if, Assuming P = 0.3 × Pref, the range of laser power P is Pref- P <P <Pref + Can be set to P. Therefore, if Pref is 5.9mW, the laser power P is selected from 15 kinds of powers such as 4.1, 4.4, 4.6, 5.1, 5.4, 5.6, 5.9, 6.2, 6.4, 6.7, 6.9, 7.2, 7.4, 7.7mW. The laser powers P are variable for each ATIP frame.

Whenever the EFM test pattern is recorded in each ATIP frame, the ID number for the laser power P should be recorded in the form of a subqcode so that the laser pattern can be distinguished by which laser power was recorded during reproduction. do.

In step B, the microcomputer 5 reads the count area of the PCA, calculates the corresponding partition of the test area, and finds the position thereof. Thereafter, the microcomputer 5 sequentially changes the fifteen laser powers calculated in step C, records EFM test patterns prepared in advance in each of the fifteen ATIP frames of the partition, and records them in the form of ID number hol sub-cucode. Through this step C, recording of one partition is completed.

The microcomputer 5 then proceeds to step D, searches for the partition recorded in step C, starts playback, and proceeds to step E. FIG. Since there are ATIP frames in which the test pattern is recorded with 15 laser powers (P) in the partition searched in step C, the digital data and the servo and playback unit 14 outputted from the A / D converter 3 every 1 ATIP frame. You can get ID data from That is, the microcomputer 5 stores digital data output from the A / D converter 3 and corresponding ID data in the internal memory every one ATIP frame in step E. FIG. Accordingly, 15 types of ID data and corresponding digital data are stored in the internal memory.

Then, the microcomputer 5 proceeds to step F to search the data stored in the step E, finds digital data included in the asymmetric tolerance range (20%) defined in the redbook standard, and finds the corresponding laser power P. Determine the optimum laser power (P). The optimal laser power P determined as described above is output through the Po terminal of the microcomputer 5 as laser power data for recording actual data. In step G, the microcomputer 5 records the number of tests in the count area.

Therefore, the optimal laser power P, which is adaptive to the change of the system state and the surrounding environment, can be determined by the steps as described above.

On the other hand, when only the A / D converter 3 is used except for the integrator 1 and the amplifier 2 of FIG. 1, since the variation range of the signal input to the microcomputer 5 is very large and wide, the sample work time is shortened. Steps such as 2 degrees may determine the optimal laser power.

As described above, since the laser power is determined in consideration of the state of the system and the change of the surrounding environment, the probability of data error occurring due to the asymmetry of the reproduction signal is lowered.

Claims (5)

An optical disk, an optical pickup for recording data on the optical disk or picking up and recording data recorded on an optical disk surface; an RF amplifier for amplifying and outputting the RF signal reproduced from the optical pickup; and the amplified RF signal. 1. An optical recording and reproducing apparatus comprising: a data reproducing unit for converting waveform equalized to EFM data and decoding and outputting the converted data, wherein the conversion means for sampling and outputting the DC component of the amplified RF signal to a predetermined period is converted into digital data. And ID data and EFM test pattern for identifying the laser power are recorded in the test area of the optical disk surface at different levels of laser power, and digital data inputted from the conversion means is asymmetric when the test area is reproduced. When having a value within the allowable range, the ID data input from the playback unit Display is the laser power to the optimum laser power determining circuit to determine the optimum laser power value, characterized in that consists of a control unit for use in recording. The optimal laser power determining circuit according to claim 1, wherein the sampling period of the converting means is a time corresponding to one ATIP frame section. 2. The optimum laser power determining circuit according to claim 1, wherein an amplifier for amplifying and outputting the DC component of the RF signal is connected to the conversion means input terminal. The optimal laser power determining circuit according to claim 1, wherein the ID data for identifying the laser power is a sub cue code. In the laser power determination method of the optical recording and reproducing apparatus, the first process of reading the reference laser power recorded in the lead-in area to calculate different levels of test laser power, and the corresponding partition of the test area by reading the count area A second process of finding an ID, a third process of recording ID data and an EFM test pattern for identifying each of the calculated test laser powers in the partition by ATIP frame units with the corresponding test laser power, and digital data at the time of reproducing the partition. And a fourth step of determining a laser power indicated by the inputted ID data as an optimum laser power when the DC component has a value within the asymmetric allowable range with the converted RF signal. .