KR100606679B1 - Method of generating recording control signal of optical record player - Google Patents

Abstract

The present invention relates to a method for generating an optimal recording signal for recording on an optical disk, and in particular, the high frequency component of the laser diode (LD) power fed back in a relatively long pattern recording period is removed and then digitized. By controlling to maintain it, it is possible to prevent the deterioration of the recording characteristic caused by the long time recording and to achieve the optimum recording. In particular, it is possible to further improve the recording quality by monitoring the LD power in the erase period and always keeping the difference from the recording power constant.

Record signal, ROPC

Description

Method for generating record control signal of optical record player {Method for record control signal generating of optical record / player}

1 is a block diagram illustrating a configuration of a recording signal generating apparatus in a conventional optical recording / reproducing player

2A to 2E are timing diagrams for implementing three levels of write strategy in FIG.

3 is a block diagram showing the configuration of a recording signal generating apparatus in the optical recorder according to the present invention;

4A to 4C are timing diagrams showing the relationship between a relatively long pattern of MPD output, a write pulse, and an erase pulse.

5A to 5D are timing diagrams showing the relationship between a relatively long pattern of MPD output, a write pulse, an erase pulse, and an RF signal.

6A to 6C are timing diagrams showing the relationship between the write pulse, the erase pulse, and the MPD output at the beginning of a sector of a DVD-RAM.

Explanation of symbols for main parts of the drawings

201: optical disc 202: optical pickup

203: encoder 204: power generation unit

205: ALPC control unit 206: LD drive unit

207: ALPC feedback section 208, 210: LPF

209: RF signal generator 200: micom

The present invention relates to a system for recording and reproducing data on an optical disc, and more particularly to a method for generating an optimal recording control signal for recording data on a disc.

In general, for rewritable discs, the recording medium is usually formed of a phase change material. Therefore, the light focused at the optical head is converted to heat, and this heat changes the state of the phase change recording medium so that the reflection amount is changed, thereby forming marks on the phase change type disk to record the pits. Here, forming a mark by a predetermined length on the disk is referred to as write strategy.

At this time, the laser light is incident on the opposite side of the reflective surface with a pit. Therefore, the pit appears as a projection when viewed from the laser incident side.

The pit has a width of 0.4 to 0.6 mu m, the length of one pit and the interval between the pit and the pit in 9 steps from 3T to 11T for a compact disc (CD) and 12T to 14T for a digital multifunction disc (DVD). Are divided into stages. Here, T means the length of one clock pulse, 3T means three clock pulses, and 11T corresponds to the length of 11 clock pulses.

In the pit group of the track wound in a spiral, there is a specific pit array at a certain interval, and the pit array that exists regularly has a synchronization signal, and the block from the synchronization signal to the next synchronization signal is called a frame. do. In this case, one frame includes a plurality of symbol data.

FIG. 1 is a block diagram illustrating a recording-related portion of a general optical disc recording / reproducing apparatus. When the laser diode (LD) driving pulse is output to the encoder 103 to record data on the disc 101, the encoder 103 is output. Converts the LD driving pulse into a signal for writing to the disk 101, that is, a write pulse, and outputs the LD driving pulse to the LD driving unit 106. That is, the encoder 103 converts the LD driving pulse into a 16-bit digital signal and divides the LD driving pulse into upper 8 bits and lower 8 bits (this is called a symbol) on a frame basis.

The 14-bit code value corresponding to 8-bit symbol data is read from a code table of a memory (not shown) to perform EFM (Eight to Fourteen Modulation) or EFM + modulation for converting 8-bit symbol data to 14 bits. Do it. That is, code tables for EFM or EFM + are mapped in memory.

The EFM or EFM + modulated data has a non-return-to zero, inverted modulation as shown in FIG. 2A by adding a margin bit (eg, 3 bits) to remove the DC component after modulation. After that, it is input to the LD driver 106. The NRZI modulation is a modulation rule for inverting data in a signal of '1'. In other words, if '1' is met, the current state is reversed.

On the other hand, the power generating unit 104 generates the power of the laser diode (LD) for the data to be recorded and converts it into an analog and then the LD driver through the Auto laser power control (ALPC) control unit 105 Output to (106). Here, the write power differs depending on the disk state according to the length of the mark to be formed.

The LD driving unit 106 is turned on / off by the NRZI modulated data in the encoder 103 to convert the LD driving voltage into the LD driving current, and then drive the LD of the optical pickup 102. In other words, the LD outputs necessary light in accordance with the driving current, and forms a pit at a required position in accordance with the servo. Here, the LD driver 106 may be inside the optical pickup 102 or may be outside the optical pickup 102.

At this time, the light output of the LD changes remarkably according to the temperature. As the temperature increases, the light power decreases, and as the temperature decreases, the light power rises. ALPC) feedback to the front monitoring photodiode PD of the feedback unit 107. The ALPC feedback unit 107 outputs the ± power level to the ALPC control unit 105 according to the LD power detected by the monitoring PD (MPD), and the ALPC control unit 105 outputs the power level fed back to the power generation unit ( In addition to the light power generated at 104, the LD output power is kept constant during recording / reproducing.

As such, when the LD output power is controlled by instantaneous feedback, this is called ALPC. On the other hand, if the LD output power is controlled for a long time during recording, this is called ROPC (Running Optimum Power Control), and ROPC is proposed only in the case of a single pulse recording type such as CD-R. This is because it is particularly important not only to allow the recording pit to be optimally formed but also to make the optimum state correspond to the temperature change or the state change of the media.

For example, in the case of the CD-R, the ROPC is performed in such a manner as to keep the value of the amount of reflection of the time when the pit is formed from the high frequency (RF) signal reflected during the pit recording. This is called the B level, and controls the driving power of the LD to keep the B level constant.

However, the above ROPC method cannot be used when multi-pulse recording is performed such as DVD-based recording media, that is, DVD-R, DVD-RW, DVD-RAM, and CD-RW media of CD type.

In other words, when data is recorded with a single NRZI modulated pulse, the shape of the pit is prevented because the thermal characteristic of the disk itself is formed like a tear drop, or the formation of the mark is distorted due to the latent heat characteristic of the disk. Multi-pulse modulation is also used to form a smooth oval. This is to perform multipulse modulation which scans a disc by dividing one single pulse into several pulses by turning on / off several times in one single NRZI modulated pulse.

In this case, the light strategy implemented by the multi-pulse is usually in the form of 2 levels, 3 levels, 4 levels. In the case of a rewritable disc, the power of each level is usually the strongest in the write power, followed by erase power, read power, and cooling power. The levels of the read power and the cooling power may be the same or different.

The LD driver 106 of FIG. 1 shows an example of three-channel switching for converting a three-level LD driving voltage into LD driving current through respective switching, and FIG. 2B shows a light strategy at this time. have. That is, three levels of write strategy are implemented by turning off the erase pulse in the recording section and turning on / off the write pulse and the read pulse. When the recording pit is formed, the erase pulse is turned on.

To this end, the encoder 103 outputs a write pulse, an erase pulse, and a read pulse to the LD driver 106. In addition, the power generating unit 104 generates each power, for example, write power, erase power, and read power, and outputs the generated power to the ALPC control unit 105, and the ALPC control unit 105 outputs the control pulses from the encoder 103. The write power, erase power, and read power fed back by the (control pulse) are added to the LD driver 106 and output.

The VI amplifier 106-1 of the LD driver 106 is turned on / off by a write pulse as shown in FIG. 2C, and converts the light power output from the ALPC controller 105 into a current. 106-2) is turned on / off by the erase pulse as shown in FIG. 2 (d) to convert the erase power output from the ALPC controller 105 into a current, and the VI amplifier 106-3 is connected to the read pulse. As a result, as shown in FIG. 2E, the read power output from the ALPC controller 105 is converted into current. When the adder 106-4 adds the currents output from the VI amplifiers 106-1 to 106-3 to drive the LD in the optical pickup 102, the multi-pulse modulated signal is recorded on the optical disk 101. do.

The reason why the above-described ROPC method cannot be applied in the multi-pulse recording method is as follows. In other words, the recording by the multi-pulse train results in a high frequency clock component being reflected in the reflected high frequency (RF) signal, and particularly high frequency noise is induced by physical changes such as pit formation.

For this reason, it cannot cope with a change in the temperature characteristic of a LD or a change of a disk characteristic especially when recording for a long time. Therefore, the recording quality cannot be maintained and the recording quality is further degraded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to remove the high frequency part from the optical pulse train during a specific time fed back during multi-pulse recording, and then digitize it so that the output power of the LD at the pit formation is constant The present invention provides a method for generating a recording control signal of an optical recorder to be maintained.

Another object of the present invention is to provide a method of generating a recording control signal of an optical recorder for monitoring the LD power of an erase section to maintain an optimum erase level.

The recording signal generating method of the optical recorder according to the present invention for achieving the above object is characterized in that the recording level is controlled to be maintained at a constant level by averaging the amount of light reflected during recording.

The amount of light reflected during the recording is digitized after low pass filtering.

The averaging of the amount of light reflected during the recording is performed only in a recording section having a pattern longer than the preset reference pattern.

And controlling a recording level to be maintained at a constant level by averaging a high frequency (RF) signal generated from an electrical signal proportional to the reflected light amount.

The recording level is controlled to be maintained only when the difference between the averaged reflected light amount signal and the high frequency (RF) signal is within a preset reference value.

The erase level turned off during the recording period is averaged to control the difference from the recording level to be kept constant.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

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

The present invention aims to keep the recording power constant by eliminating high frequency portions from the front monitoring PD output and digitizing them when writing long patterns (e.g., sync patterns).

FIG. 3 is a block diagram of a recording signal generating apparatus of an optical recorder / player according to the present invention, which includes a low pass filter (LPF) 208 for low-pass filtering and averaging the output of the APLC feedback unit 207; A high frequency (RF) signal generator 209 for generating a high frequency (RF) signal from an electrical signal output in proportion to the light reflection signal from the optical pickup 202, and an LPF 210 for low pass filtering the high frequency (RF) signal. And a microcomputer 200 for digitizing the outputs of the LPFs 208 and 210, respectively, so that the recording power is kept constant.

The present invention configured as described above is intended to maintain the value after averaging the values sampled in the relatively long sections of the recording section.

For this purpose, when a long pattern (for example, a sync pattern) is recorded, that is, a pattern longer than a preset reference pattern (for example, 5T or more) is recorded, the LPF 208 generates a high frequency component at the output of the ALPC feedback unit 207. After the removal is output to the microcomputer 200 to digitize. That is, when the high frequency component is removed by low pass filtering the output of the ALPC feedback unit 207, a long pattern signal is averaged. The microcomputer 200 digitizes this value and then the digitized value is recorded by the recording power generation unit 204. Control to maintain. For example, the recording power generating unit 204 raises the current power level if it is smaller than the digitized value, and lowers it when it is high to reduce the distortion of the pit. Therefore, the recording characteristic can be maintained optimally.

FIG. 4A shows the output of the ALPC feedback unit 207 having a relatively long pattern, and FIG. 4B shows the light pulse at this time. The present invention averages and digitizes values of sections having a relatively long pattern, such as the circled portion of FIG. At this time, the ROPC is not performed in the recording section for recording the pattern shorter than the reference pattern. This is because sampling and averaging the values of the recording sections having a short pattern may be influenced by noise and thus may cause false control. The erase pulse is turned off in the recording section in which the write pulse is turned on / off as shown in FIG.

Meanwhile, in another embodiment of the present invention, the high frequency component of the high frequency (RF) signal having a relatively long pattern is removed from the LPF 210, averaged, and digitized, and then the digital value is constant in the recording power generation unit 204. In other words, it may be controlled to maintain a constant level in multiple pulses.

In addition, both the output of the ALPC feedback unit 207 and a high frequency (RF) signal may be used. This is to take into account the defect of the disk and the like. That is, the output of the ALPC feedback unit 207 and the output of the high frequency (RF) signal generation unit 209 at the same point, for example, a recording section having a relatively long pattern as shown in the circle portion of FIG. 5, at the respective LPFs 208 and 210. After low pass filtering, it is output to the microcomputer 200. At this time, if the difference between the two values is more than the reference value, the microcomputer 200 determines that sampling is wrong and discards the values without using them for control. If the difference between the two values is smaller than the reference value, it is determined that sampling is properly performed and the values are used for control. Therefore, the recording characteristic can be maintained more optimal.

On the other hand, it is also important to maintain the erase level optimally. This is because distortion may occur in the recording pits due to latent heat characteristics if the erasure level is not formed properly.

Therefore, in the present invention, the erase level is kept constant for each sector. In particular, the correlation with the recording level is evaluated so that the erase level is optimized.

For this purpose, the erase level of a relatively long pattern is sampled, or the erase level passed through the LPF which removes the high frequency portion of the multi-pulse is digitally controlled so that the difference between this value and the recording power level becomes constant.

In particular, in a phase change type disc such as a DVD-RAM, that is, a disc for repeated recording, as shown in Figs. In other words, the erase level is digitized to control the value thereof to be optimal. That is, a dummy pattern of a long pattern that is not recorded at the beginning of a sector is set as a DC erasure section, and the value of the section is averaged through the ALPC feedback unit 207 and the LPF 208 and then digitized through the microcomputer 200. To keep the erase level optimal. At this time, it is possible to prevent the deterioration of recording characteristics due to long time recording by evaluating the correlation with the recording power and controlling the two power levels to always maintain a constant level.

As described above, according to the method of generating a recording control signal of the optical recorder according to the present invention, the high frequency component of the LD power fed back in a relatively long pattern recording period is removed and digitized so that the LD output power is kept constant at this value. By controlling, deterioration of recording characteristics caused by long time recording can be prevented and optimal recording can be performed. In particular, it is possible to further improve the recording quality by monitoring the LD power in the erase period and always keeping the difference from the recording power constant.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (10)

In the recording control signal generation method of an optical recorder for driving a laser diode in the form of a multi-pulse, A method of generating a recording control signal in an optical recorder, characterized in that the recording level is maintained at a constant level by averaging the amount of light reflected during recording. The method of claim 1, And digitizing the amount of light reflected during the recording after low pass filtering. The method of claim 1, And averaging the amount of light reflected during the recording is performed only in a recording section having a pattern longer than a predetermined reference pattern. The method of claim 1, And averaging the high frequency (RF) signal generated from the electrical signal proportional to the reflected light amount so as to control the recording level to be maintained at a constant level. The method of claim 4, wherein And averaging the high frequency (RF) signal only in a recording section having a pattern longer than a predetermined reference pattern. The method of claim 4, wherein And the high frequency (RF) signal is digitized after low pass filtering. The method of claim 4, wherein And a recording level is controlled to be maintained at a constant level only when a difference between the averaged reflected light amount signal and a high frequency (RF) signal is within a preset reference value. The method of claim 1, A method of generating a recording control signal in an optical recording / reproducing apparatus, characterized by averaging the erase level turned off during the recording period so that the difference from the recording level is kept constant. The method of claim 8, And a low pass filtering of the erase levels of a pattern longer than a predetermined reference pattern and averaging them. The method of claim 8, And setting a DC erase period in an unrecorded area at the beginning of a sector and controlling the difference between the level and the recording level of the DC erase period to be kept constant.

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