KR100532489B1 - Recording controlling method of an optical disk and an optical recording apparatus therefor - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc recording method and apparatus thereof, and more particularly to a recording control method for varying recording power according to a recording speed, a mark recording density, and a type of recording medium, and an optical disc recording apparatus suitable therefor.

In the recording control method according to the present invention, in the recording control method of the optical disc recording apparatus which compares the power of the optical signal output from the laser diode and the reference power value and controls the output of the laser diode according to the comparison result, each recording mark Preparing a plurality of reference power values corresponding to the recording speed or the recording density each time; Selecting one of the plurality of reference power values for a recording mark to be recorded according to a recording speed or recording density; And controlling the recording power of the laser beam according to the selected reference power value.

The recording control method and apparatus according to the present invention has the effect of improving the recording performance of the optical disc recording apparatus by setting the recording power differently according to the recording speed, the recording density, and the type of the recording medium.

Description

Recording control method of an optical disk and an optical recording apparatus therefor}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc recording method and apparatus thereof, and more particularly to a recording control method for varying recording power according to a recording speed, a mark recording density, and a type of recording medium, and an optical disc recording apparatus suitable therefor.

In the multimedia age, high-capacity recording media are required, and optical recording apparatuses using such high-capacity recording media include MODD (Magnetic Optical Disc Driver), CD (Compact Disk), CD-R / RW (CD Rom / ReadWrite), DVD (Digital Versartile Disk), DVD-RAM / RW (DVD Random Access Memory / ReadWrite) recording device, and the like.

In such optical recording apparatuses, the time for forming the recording marks of the same length decreases in inverse proportion to the increase in the recording speed, so that more precise recording control is required as the recording speed increases.

In general, an optical disc records signals by heating or cooling a recording film by laser light and natural cooling. The crystal state of the recording film changes depending on the degree of heating and the cooling rate, and the crystal / non-crystalline state of the recording film corresponds to the value (0 or 1) of the binary signal, respectively.

The degree of heating of the recording film is determined by the recording power and the heating period of the laser light. That is, by irradiating the recording film with a laser light having an appropriate recording power for an appropriate heating period, a recording mark of a desired length is formed.

However, even in the formation of recording marks of the same length, when the recording speed changes, that is, when the heating period is changed, the degree of thermal integration in the recording film is changed so that the unevenness of recording, in particular, the start and end positions of the recording marks are shaken. Jitter occurs. This nonuniformity of recording also occurs in the case where the recording density changes.

Accordingly, there is a need for an improved recording control method for controlling thermal integration in a recording film as the recording speed and recording density change appropriately.

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording control method for improving recording quality by minimizing occurrence of recording irregularities due to changes in recording speed and recording density in an optical disc recording apparatus.

 Another object of the present invention is to provide an apparatus suitable for the above recording control method.

In order to solve the above technical problem, the recording control method according to the present invention

In the recording control method of the optical disc recording apparatus which compares the power of the optical signal output from the laser diode and the reference power value, and controls the output of the laser diode according to the comparison result,

Preparing a plurality of reference power values corresponding to the recording speed or the recording density for each recording mark;

Selecting one of the plurality of reference power values for a recording mark to be recorded according to a recording speed or recording density; And

And controlling the recording power of the laser beam according to the selected reference power value.

Here, the recording marks are classified into a plurality of groups according to the length, and more preferably, a plurality of reference power values corresponding to the respective groups are prepared.

Further, in the recording control method according to the present invention, it is preferable that the plurality of reference power values for the recording marks are set differently depending on the type of recording medium in addition to the recording speed or recording density.

An optical disc recording apparatus according to the present invention for solving the above other technical problem is

In the optical disk recording apparatus for comparing the power of the optical signal output from the laser diode and the reference power value, and controlling the output of the laser diode in accordance with the comparison result,

A data determination unit for determining the length of the mark to be recorded;

A recording pulse generation unit for generating a recording pulse corresponding to a mark to be recorded according to the determination result of the data determination unit;

A laser diode driver for driving the laser diode according to a write pulse output from the write pulse generator;

A photodiode detecting the magnitude of the optical signal output from the laser diode;

A comparison unit comparing the output of the photodiode with a reference power value;

A calculating unit controlling the output power of the laser diode according to a comparison result of the comparing unit; And

A control unit for applying a reference power value applied to the comparison unit,

Here, the control unit

Each recording mark has a plurality of reference power values corresponding to the recording speed or the recording density, and selects one of the plurality of reference power values for the recording mark to be recorded according to the recording speed or the recording density, A reference power value is applied to the comparison unit.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the configuration and operation of the present invention.

1 is a block diagram showing the structure of a conventional optical recording control device.

In the apparatus shown in Fig. 1, the data determination unit 110 determines the number of Ts (where T is the inverse of the channel clock) of each mark and space with reference to the input NRZI data. The recording waveform control unit 120 generates control signals corresponding to recording marks to be recorded according to the determination result of the data determination unit 110. The control signals include read control signals, peak control signals, bias control signals, and the like.

The recording pulse generator 140 generates a recording pulse according to the control signals provided from the recording waveform controller 120, and the laser diode driver 150 lasers according to the recording pulse provided from the recording pulse generator 140. The diode 152 is driven.

The gain adjusting unit 158 adjusts the gain of the photodetection signal input through the photodiode 156 according to the operation mode of the optical recording apparatus, that is, whether recording or reproducing is performed. The comparator 160 compares the power of the photodetection signal output from the gain adjuster 158 with a reference power, and the up / down counter 170 is up / down according to the result of the comparator 160. Down count, the digital-analog converter (DAC) 180 converts the up / down count value to an analog and applies it to the recording pulse generator 140.

The reference powers applied to the comparator 160 include a reference read power, a reference peak power, a reference bias power, and the like. Each reference power is compared with the voltage of the photodetection signal output from the gain adjusting unit 358 sampled in the read power period, the peak power period, and the bias power period, and applied to the write pulse generator 140 according to the comparison result. The read power, peak power, bias power, and so on are changed.

2 (a) to 2 (e) are waveform diagrams for showing the operation of the apparatus shown in FIG.

A write pulse as shown in FIG. 2E is generated for input Non Return to Zero Inversion (NRZI) data composed of 3T, 5T, 11T, etc., as shown in FIG. Here, the level of NRZI data corresponds to the marks and spaces formed on the optical disc. In other words, the section in which the NRZI signal holds "1" corresponds to the section in which the recording mark is formed, i.e., the mark, and the section in which "0" remains, corresponds to the section in which the contents recorded on the optical disc are erased, i. do.

In the multi-pulse recording method, the recording pulse is generally composed of a first pulse, a multi pulse, a last pulse, a cooling pulse, and the like. The first pulse is a pulse for forming the standing edge of the recording mark, and the multi-pulse is a pulse forming the body between the standing edge and the falling edge in the recording mark, that is, the last pulse forming the falling edge of the recording mark. And a cooling pulse is a pulse for forming a trailing portion after the falling edge of the recording mark.

In forming the recording marks having different lengths, the first pulse, the last pulse and the cooling pulse are not changed, and only the number of pulses of the multi pulses is changed.

The write pulses of Fig. 2 (e) are read control signals as shown in Fig. 2 (b), peak control signals as shown in Fig. 2 (c), and from one to as shown in Fig. 2 (d). It is formed by adding read power, peak power, and bias power, each controlled by three or more bias control signals.

That is, in the period in which the read power control signal is active, the write pulse has read power (or cooling power), and in the period in which the peak power control signal is active, the write pulse is peak power. In the period in which the bias power is active, the write pulse has a bias power or erase power.

According to the 2.6GB DVD-RAM standard, the waveform of the recording pulse is composed of the first pulse, multi pulse chain and the last pulse, and the rising edge of the first pulse of the basic recording pulse is T than the rising edge of the recording mark. The delayed edge of this first pulse can be shifted back and forth in units of 1 ns (nano second), the last pulse can also be shifted back and forth in units of 1 ns, and the multi-pulse consists of several short pulses. The accumulation of heat in the body of the recording mark is reduced to prevent deformation of the recording mark.

Referring to the waveform diagram as shown in Fig. 2, if the recording speed or recording density is changed, T is changed and thus the time for forming the recording mark is changed. The time for forming the recording mark decreases in inverse proportion to the recording speed and the recording density. As the time for forming the recording mark, in particular, the heating time, is reduced, it becomes difficult to heat the recording film to a sufficient degree for melting, so that the nonuniformity of the recording, particularly jitter, is likely to increase.

In order to overcome this, the recording control method according to the present invention controls the power of the laser light, in particular the peak power, in accordance with the recording speed or the recording density. For example, in recording short recording marks, an increase in the recording speed causes the recording film to be sufficiently heated so that the peak power can be increased to offset the reduced heating time.

3 is a flowchart showing a recording control method according to the present invention.

First, a plurality of reference power values corresponding to the recording speed or the recording density are set for each recording mark (s302).

One of a plurality of reference power values set for the recording mark to be recorded is selected according to the recording speed or the recording density (s304).

The power of the optical signal output from the laser diode is controlled according to the selected reference power value (s306).

In the conventional recording control method, that is, the method using the same reference power regardless of the recording speed and the recording density, in the case of 3T, which is the shortest length mark, the recording mark may be small or not formed properly due to insufficient preheating or lack of optical power. On the contrary, in the case of 11T, which is the longest mark, the recording mark may be largely formed by heat accumulation or may affect the adjacent tracks, causing cross erase.

As described above, the recording quality may be affected only by the size of the mark, but may also cause a greater influence depending on the combination of the mark and the space. For example, if the mark of 3T is recorded after the space of 11T, the recording film may be supercooled during the space space of 11T, and the preheating shortage may occur. Heat may accumulate during the mark section of 11T in a state in which the heat is not sufficiently cooled and the heat remains. Thus, overheating may occur.

This lack of preheating or overheating causes the size of the recording mark to be uneven, which results in jitter, which is a time variation, which degrades the recording performance of the optical recording apparatus.

In the present invention, it is possible to form the recording mark at an appropriate recording power according to the recording speed and recording density, thereby minimizing the non-uniformity of the recording mark due to lack of heat or overheating, thereby minimizing time jitter and optical recording. This improves the recording performance of the device.

On the other hand, considering the combination of marks and spaces, there are 10 types of marks or spaces on the DVD: 3T, 4T, 5T, 6T, 7T, 8T, 9T, 10T, 11T, and 14T. There are 100 combinations of, 200 combinations of the current mark and the next space, and 100 combinations.

In addition, considering the implementation of a multiplexer for selecting one of a plurality of reference powers set for each combination, the size of the hardware becomes very large, which makes the calculation inconsistent for cost and power consumption.

In consideration of this, if the mark and space are classified into several groups and combined based on the group, the number of combinations is reduced by that, and the performance can be improved while optimizing the size of the hardware.

4 shows two grouping examples. In the first example shown in the upper part of FIG. 4, the group is divided into four groups, but GROUP1 is divided into 3T, GROUP2 is divided into 4T-7T, GROUP3 8T-9T, and GROUP4 is divided into 10T-14T. On the other hand, in the second example shown in the lower side of Figure 4 is divided into four groups, but GROUP1 is divided into 3T, GROUP2 is 4T, GROUP3 is 5T, and GROUP4 is 6T-14T.

The division of each group is performed by the first to third grouping pointers, and sets the value of the grouping pointer differently according to the recording speed, the recording density, and the type of recording medium used.

That is, in the present invention, the reference power is set to one of four values corresponding to four groups, and the group and the reference power are selected according to the recording speed, the recording density, and the type of recording medium used.

Also, the value of the grouping pointer is changed in accordance with the recording speed, the recording density, and the type of recording medium used.

Changing the value of the grouping pointer according to the recording speed, recording density, and type of recording medium used can be performed by software, and selecting one of the four reference powers can be performed by simple hardware. The size of the hardware for the write control can be optimized.

5 is a block diagram showing the configuration of the recording control apparatus according to the present invention.

The apparatus shown in FIG. 5 includes a data discriminating unit 390, a recording waveform control unit 320, a control unit 330, a recording pulse generator 340, a laser diode driver 350, a laser diode 352, and a disk 354. ), A photodiode 356, a gain adjuster 358, a comparator 360, a counter 370, an adder 380, and a DAC 390.

The laser diode driver 350, the laser diode 352, the photodiode 356, the gain adjuster 358, the comparator 360, the up / down counter 370, the calculator 380, and the DAC 390 An auto laser-diode power control (ALPC) operation is performed in association with the optical signal reflected from the disk 354.

When a write enable signal and NRZI DATA indicating a recording start are input, the data determination unit 310 determines how many Ts each mark and space correspond to.

The determination result of the data determination unit 310 is provided to the recording waveform generator 320, and the recording waveform generator 320 generates control signals suitable for the recording medium to be used and the set recording speed.

The controller 330 is responsible for initializing and controlling the blocks shown in FIG. 5, and in particular, sets an initial value of the up / down counter 370 and reference powers set in the DAC 390. The initial value at this time is a reference value of the recording power corresponding to the recording speed and the recording density.

The output of the up / down counter 370 is input to the calculation unit 380, and the calculation unit 380 simply passes it through, outputs an average for a predetermined time, or performs a predetermined filtering process, and then writes each recording power. The corresponding value is outputted to the recording pulse generator 340. The write pulse generator 340 basically consists of a multiplexer, and selects one of the respective write powers output from the calculator 380 according to the control signal generated by the write waveform generator 320 to generate a laser diode driver ( 350).

 At this time, the laser diode driver 350 outputs a current value corresponding to the write power of the input write pulse to the laser diode 352, and the laser diode 352 is the magnitude of the current output from the laser diode driver 350. The laser beam having the optical power corresponding to the output is output.

A portion of the laser light of the laser diode 352 is directly transmitted to the F photo diode (382) to form a close-loop for APC (Auto Power Control) and used to maintain a constant optical power.

Most of the remaining laser light is incident on the disk 354 through an objective lens (not shown). The laser light reflected from the disk 354 is transmitted to a photo diode 356 to perform an operation for recording / reproducing through signal processing.

Switch 384 can select the output of F photodiode 382 or the output of photodiode 356, the output of which is input to variable gain regulator 358. The variable gain adjuster 358 is implemented with a variable gain amp (VGA).

The output of the DAC 390 for setting the reference power corresponding to the recording speed and the recording density is input to the comparator 360 and the output of the variable gain adjuster 358 is also input to the comparator 360C. The comparator 360 compares the two input values and sets the counting direction (up or down) of the up / down counter 370 according to the result.

The operation of the apparatus shown in FIG. 5 will be described by way of example.

When controlling the output of the laser diode through the Close-Loop for APC (Auto Power Control), for some reason (for example, the output change of the laser diode due to temperature change), When the output of the set F photodiode or photodiode becomes small, the comparator 360 outputs a "Low" value to increase the count value of the up / down counter 370. In this case, an initial value corresponding to the reference power is set in the up-down counter 370, and a value corresponding to the reference power is set in the DAC 390.

When the count value of the up / down counter 370 is increased, the output of the up / down counter 370 is transmitted to the write pulse generator 340 through the calculator 380, so that the input current of the laser diode 352 is increased. To maintain a constant amount of light.

On the contrary, when the output of the F photodiode 382 or the photodiode 356 is greater than the output of the DAC 390, the comparator 360 outputs a "High" value to decrease the count value of the up / down counter 370. Let's do it. When the count value of the up / down counter 370 is decreased, the input current of the laser diode 352 is decreased to maintain a constant amount of light.

Here, the operation clock of the up / down counter 370 may be variably set in consideration of the operation time of the target APC (Auto Power Control) Close-Loop.

Meanwhile, the controller 330 includes a table storing reference power values corresponding to each group as described with reference to FIG. 4. The controller 330 reads a corresponding reference power value from a table according to the recording speed, the recording density, and the type of the recording medium, and sets an initial value of the up / down counter 370 and a reference power value of the DAC 390. .

6 is a waveform diagram showing examples of recording power according to the present invention. Fig. 6 (a) shows input NRZI data, Fig. 6 (b) shows an example of recording waveforms on a recording medium of CD-R type, and Fig. 6 (c) shows CD-R type with overdrive. An example of recording waveforms on a recording medium is shown, and Fig. 6 (d) shows an example of recording waveforms on a recording medium of DVD type, and Fig. 6 (e) shows recording on a recording medium of DVD_RAM or DVD-RW type. Examples of waveforms are shown.

The examples shown in FIG. 6 correspond to the second grouping example shown at the bottom of FIG. 4. In addition, the overdrive power is a power applied to enhance the standing edge and falling edge portions of the recording mark.

The present invention is not limited to the above-described embodiment, and of course, modifications may be made by those skilled in the art within the spirit of the present invention. That is, the novel adaptive recording pulse waveform proposed in the present invention can be used in most high density optical recording devices.

As described above, the recording control method and apparatus according to the present invention has the effect of improving the recording performance of the optical disc recording apparatus by setting the recording power differently according to the recording speed, the recording density, and the type of the recording medium.

1 is a block diagram showing a conventional optical recording device.

2 (a) to 2 (e) are waveform diagrams for showing the operation of the apparatus shown in FIG.

3 is a flowchart showing a recording control method according to the present invention.

4 shows grouping examples in the write control method according to the present invention.

5 is a block diagram showing the configuration of the recording apparatus according to the present invention.

6 is a waveform diagram showing examples of recording pulses according to the recording control method according to the present invention.

Claims (4)

In the recording control method of the optical disc recording apparatus which compares the power of the optical signal output from the laser diode and the reference power value, and controls the output of the laser diode according to the comparison result, Preparing a plurality of reference power values corresponding to the recording speed or the recording density for each recording mark; Selecting one of the plurality of reference power values for a recording mark to be recorded according to a recording speed or recording density; And And controlling the recording power of the laser beam according to the selected reference power value. The method of claim 1, And the recording marks are classified into a plurality of groups according to length, and a plurality of reference power values corresponding to the respective groups are prepared. The method of claim 1, And a plurality of reference power values for recording marks are set differently depending on the type of recording medium in addition to the recording speed or recording density. In the optical disk recording apparatus for comparing the power of the optical signal output from the laser diode and the reference power value, and controlling the output of the laser diode in accordance with the comparison result, A data determination unit for determining the length of the mark to be recorded; A recording pulse generation unit for generating a recording pulse corresponding to a mark to be recorded according to the determination result of the data determination unit; A laser diode driver for driving the laser diode according to a write pulse output from the write pulse generator; A photodiode detecting the magnitude of the optical signal output from the laser diode; A comparison unit comparing the output of the photodiode with a reference power value; A calculating unit controlling the output power of the laser diode according to a comparison result of the comparing unit; And A control unit for applying a reference power value applied to the comparison unit, Here, the control unit Each recording mark has a plurality of reference power values corresponding to the recording speed or the recording density, and selects one of the plurality of reference power values for the recording mark to be recorded according to the recording speed or the recording density, And a reference power value is applied to said comparator.