KR100532093B1 - Optical disc recording apparatus and method for improving the characteristic of cross erase - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording method and apparatus for improving cross erase by controlling the power of a laser during rewriting in a disk recording and reproducing method.

According to the present invention, by lowering and recording the laser power at a level below the reproduction power in the portions where the erase portions before and after the overwriting overlap, the cross erasure phenomenon affecting the signals of adjacent tracks due to the thermal effect during recording is improved. Not only can this be done, it also has the effect of improving the cycleability on the overwriting track.

Description

Optical disc recording apparatus and method for improving the characteristic of cross erase

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc recording apparatus and method, and more particularly, to improve cross erase by controlling power of a laser during rewrite in a land / groove recording and reproducing method. An optical disk recording method and apparatus for performing the above.

As a non-contact information recording medium used in an optical disc player, an optical disc is developing in a direction of high capacity, high speed, and high density in accordance with the progress of the information society. In particular, technology related to optical discs capable of recording / reproducing high-density information, such as DVD (Digital Versatile Disc) random access memory (RAM), has been actively developed in relation to recording / reproducing video information on multimedia or high-quality TV. It is becoming. Accordingly, there is a need for the development of high-density optical disk media that provides further improved capacity in response to the advent of the next-generation multimedia market.

FIG. 2 is a cross-sectional view of a general optical disk, in which the lower dielectric film 12, the recording film 15, the upper dielectric film 13, the second reflective film 16, and the first reflective film 14 are placed on the substrate 11 in this order. Consists of.

In order to manufacture a high density optical disk, recording density per unit area must be increased. One way to increase the recording density is to reduce the size of the laser spot. The size of the laser spot is proportional to the wavelength λ of the light beam and inversely proportional to the numerical aperture. Accordingly, in order to reduce the size of the laser spot, it is necessary to reduce the wavelength of the light beam or use an objective lens having a high numerical aperture.

Through such a method, the interval between tracks of the high density optical disc is gradually decreasing.

As another method of increasing the recording density within the limited recording area of the optical disk, an optical disk having a structure which can record information in each of the land and groove areas formed in the optical disk has already been proposed.

Typically such optical discs are formed from an inner circumference to an outer circumference with a plurality of tracks interconnected in a spiral structure. Each track is formed with grooves drawn in a predetermined depth and lands having a surface height of the disk, and these lands and grooves are alternately formed between adjacent tracks. A mark representing data information is then formed on these lands and grooves by laser power corresponding to the recording pulse pattern.

In a disc drive using such a high-density optical disc as a recording medium, the conventional recording pulse pattern according to the recording state of the track before and after overwriting in Figs. 3 (a), (b) or 5 (a), (b) As shown in Fig. 3 (c) or Fig. 5 (c), it is represented by the write peak power Pp and the erase power Pb. However, such a recording pattern receives heat in all domains of the recording and erasing power during overwriting, and thus, in the case of the land / groove recording method, data may be recorded in a groove area, for example. In this case, a cross erase phenomenon occurs in which data recorded in an adjacent land area is erased by a row generated in a recording section of an overlapping area before and after overwriting, thereby deteriorating reliability of data of an adjacent track. There was this.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a cross for lowering and recording the power of the laser below the reproduction power when the erase portion before overwriting and the erase portion at overwriting overlap when the data is rewritten. The present invention provides an optical disk recording apparatus and method having improved erase characteristics.

In order to achieve the above technical problem, an optical disk recording apparatus having improved cross erasure characteristics according to the present invention includes a pickup including a laser, a recording / reproducing signal processing unit, a servo unit, and a control unit. In the apparatus, in the recording mode, the control unit compares the reproduction signal reproduced on the track to be recorded by the recording / reproduction signal processing unit with the modulation recording signal to be recorded, so that only the reproduction signal has a recording mark and the recording signal has a recording mark. The control signal generator and the first control signal for generating the first control signal, the second control signal if both signals have no recording mark, and the third control signal if the recording signal has a recording mark. When the first control signal is applied, the laser generates power of the first erase level, and the second control When a call is applied, the laser generates a second erase level of power lower than the first erase level, and when the third control signal is applied, the laser power generates the predetermined multi-pulse power. It characterized in that it comprises a laser pulse control unit for controlling the.

According to another aspect of the present invention, there is provided an optical disk recording method having improved cross erasure characteristics according to the present invention. Determining whether the erase area is overlapped by comparing the pattern recorded in the track to be recorded with the pattern to be recorded when the result of the determination of step (a) is in the recording mode. Step and (c) As a result of the determination in step (b), when the pattern to be recorded is an erasing area and the recorded pattern is an area with a recording mark, the laser generates a predetermined first erasing power, and the recording The laser generating a second erase power lower than the first erase power when both the patterned pattern and the pattern to be written are erase regions. It shall be.

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

First, an optical disk recording apparatus having improved cross-raise characteristics of the present invention will be described.

As shown in FIG. 1, the optical disk recording apparatus having improved cross erasure characteristics according to the present invention includes a pickup 100, a recording / reproducing signal processor 200, and a controller 300. As shown in FIG.

Here, the pickup 100 is composed of an objective lens 2, a beam splitter 3, a photo detector 4, and a laser 5 in detail, and the recording / reproducing signal processor 200 includes an arithmetic circuit 6, It consists of the channel 1, 2 processors (7, 8) including the known DSP (Digital Signal Processor) processing blocks (not shown), the control unit 300 is a control signal generator 9 and a laser pulse controller ( 10) is included.

After the track to be recorded on the disk 1 is searched in the recording mode, the light generated by the laser 5 is output to the disk 1 through the objective lens 2 and the beam splitter 3. Then, the light reflected from the disk 1 is input to the photo detector 4 through the splitter 3.

Then, the photo detector 4 converts the input optical signal into an electrical signal and outputs the electrical signal.

The converted electrical signal calculates a signal to be used for signal processing and a signal to be used for servo control in the arithmetic circuit 6, and controls the signal processing signal to the channel 1 processor 7 and the tracking control to the channel 2 processor 8. The control signals to be used in the signal and the focus control signal are separated and output.

The channel 1 processor 7 then amplifies, equalizes and decodes the signal and outputs it to the control signal generator 9.

The control signal generator 9 inputs a reproduction signal input through the channel 1 processor 7 and a modulation recording signal that modulates a signal to be recorded, and analyzes and compares the input signals to correspond to an area where a recording mark is formed. It is judged whether or not the recording mark corresponds to the erase area where no mark is formed, and the following recording control signals are generated.

As an example, in the case where the mark edge recording method is adopted as the recording method, the method of controlling the recording power according to the present invention will be described with reference to FIGS. 4 (a) -4 (c).

Then, assume that the recording state of the disc before overwriting is as shown in Fig. 4A, and the track to be recorded is a groove area in which the track is the center track.

In this case, if the state of the pattern to be recorded on the disk after overwriting is the same as in Fig. 4 (b), the control signal generator 9 compares the reproduction signal with the recording signal to determine the erased portion before overwriting and the time of overwriting. When the erase portions overlap (section a), a second control signal for generating a recording pattern below the reproduction power is generated. When the reproduction signal has only a recording mark and the recording signal has no recording mark (section b), the first control signal is generated. A control signal is generated, and if the recording signal has a recording mark, a third control signal is generated.

Then, the laser pulse controller 10 controls the power of the laser 5 according to the control signals generated by the control signal generator 9.

That is, when the first control signal is applied, the power Pb of the first erasing level shown in FIG. 4C is generated by the laser 5, and when the second control signal is applied, the second erasing is performed. The power Pm of the level is generated by the laser 5, and when the third control signal is applied, the multi-pulse for forming the recording mark is controlled by the laser 5 to be generated.

If the power Pm of the second erasing level is set below the reproduction power, the adjacent tracks are not thermally affected when overwriting in the portion where the erase portion before overwriting and the erase portion at overwriting overlap.

Therefore, in the portion where the erase parts before and after the overwriting overlap, power Pm of the second erasing level below the reproduction power is generated, and when the previously recorded mark part is reached during recording, the first control signal Is converted to power Pb.

Next, an optical disc recording method having improved cross erasure characteristics according to the present invention will be described.

FIG. 7 is a flowchart illustrating a control operation of the controller 300 shown in FIG. 1.

In step 701, it is determined whether the optical disc player is in the overwrite mode (recording mode).

In step 702, the pattern Z 'recorded in the track to be recorded and the pattern Z to be recorded are compared with each other in the overwrite mode to determine whether both patterns are in the erasing area Ze.

Then, in step 703, when the recording pattern before and after overwriting is not in the erasing area Ze, multi-pulse is generated in the portion where the recording mark exists among the recording patterns to be overwritten, and the recording is performed among the recording patterns before overwriting. The first erasing power Pb is generated in the portion where the mark is present and there is no recording mark among the recording patterns to be overwritten.

In step 704, when the recording pattern before and after overwriting is in the erasing area Ze as a result of the determination in step 702, the second erasing power Pm having a level lower than the first erasing power Pb is generated.

Here, the size of the second erasing power Pm is 0 mW or more in order not to have a thermal effect on the adjacent track, and it is effective to determine the level below the reproduction power.

In order to examine the effects of the present invention as described above, cross erasure characteristics and overwriting jitter according to the prior art and the present invention are measured using the recording patterns of FIGS. 3 and 4 in the mark edge recording method. 8 is shown. Measurement conditions include wavelength 635 nm, track pitch 0.56 μm, minimum bit length 0.293 μm, recording speed 8.6 m / s, playback speed 5.6 m / s, maximum recording power (Pp) 13.0 mW, first erasing power (Pb) 5.0 mW, The second erasing power Pm was set to 0.2 mW.

In particular, in the cross erasure measurement, the initial jitter value of the area to be measured (displayed as 0 times in the graph) was measured as 10 overwriting values, and the measurement in the groove area was affected by the overwriting in both lands. Is shown in FIG. It can be seen that in the overwriting cyclability characteristic, the present invention is superior to the conventional art by 100,000 times to 1%, and cross erasure characteristic to about 10,000 to 2%. This means that the area exposed by the second erasing power Pm has less thermal effect on the groove (or land) in the adjacent track than in the prior art.

The power conversion according to the erase power control method of the present invention takes several nsec so that a residual recording signal can be detected. However, when recording at 8.6 m / s faster than the first generation DVD-RAM standard, 1/2 Tw of multi-pulse is increased. Since it is 8.5 nsec, compared to the minimum recording mark 3Tw, the signal of the part which cannot be completely erased by the time accompanying power conversion becomes very small. Since the area written below the reproduction power has no thermal effect, not only can the cross erasure phenomenon of erasing the signal of the adjacent track be improved, but also the cyclability in the current area is improved. .

Nevertheless, when the present invention is applied to the mark edge recording method, since the absolute jitter value according to the overwriting is 10 to 13% and 100 to 14%, the value is still high enough to cause a data error. .

This may be regarded as the effect of the residual erase due to the time delay generated when the erase power is changed from the Pm level to the Pb level.

When the present invention is applied to the pit position recording methods shown in Figs. 6 (a) to 6 (c) in order to reduce the influence of the residual erase by the mark edge recording method as described above, cross erasure and overwriting cycleability can be further improved. have.

That is, in the case where the conventional recording pattern is applied to the pit position recording method, as shown in Figs. 5A to 5C, the same erasing is performed between the pit and the pit irrespective of the state of the pattern before recording. The power was recorded. However, when the recording pattern according to the present invention is applied to the pit position recording method, as shown in Figs. 6 (a)-(c), the erasing power level is changed in accordance with the recording state by detecting the recording state before the recording. In this case, since the erase area is longer than that of the mark edge recording method shown in Figs. 4A to 4C, the cross erasure phenomenon can be remarkably improved. In addition, even if a residual recording signal exists, an error occurrence rate during data reproduction can be reduced due to the mark position detection.

As shown in Fig. 10, it can be seen that the CNR characteristic according to the overwriting cycle capability is improved when the recording method according to the present invention is applied to the pit position recording method as compared with the conventional technology.

As mentioned above, the laser power control apparatus and method for lowering and recording the laser power at a level below the reproduction power in the portions where the erase portions before and after the overwriting according to the present invention overlap is applied to the mark edge recording method and the pit position recording method. When applied, it can be seen that compared to the prior art, it is possible to improve the cross erasure phenomenon and the jitter due to the cycle ability.

In particular, it can be seen that the pit position recording method to which the present invention is applied improves the jitter characteristic by cross erasure and cycle ability more remarkably than the mark edge recording method.

The optical disk recording apparatus and method with improved cross erasure characteristics according to the present invention are not limited to the mark edge recording method and the pit position recording method of the magneto-optical disk drive applied in the embodiment of the present invention. It is well known to those skilled in the art that it can be applied to the recording method.

As described above, according to the present invention, in a portion where the erased portions before and after the overlapping overlap, the laser power is recorded at a level lower than the reproduction power, so that the cross eras affects the signals of adjacent tracks due to the thermal effect during recording. Not only can the phenomenon be improved, but the jitter characteristic according to the cycle ability in the overwriting track can be improved.

1 is a configuration diagram of an optical disk recording apparatus having improved cross erasure characteristics according to the present invention.

2 is a cross-sectional view showing the structure of a general phase change optical disk.

Fig. 3A shows the marks recorded on the track before overwriting in the mark edge recording method for explaining the prior art.

Fig. 3B shows the marks recorded on the track after overwriting in the mark edge recording method for explaining the prior art.

Fig. 3C shows a recording pulse pattern in the mark edge recording method according to the prior art.

Fig. 4A shows the marks recorded on the track before overwriting in the mark edge recording method for explaining the present invention.

Fig. 4B shows the marks recorded on the track after overwriting in the mark edge recording method for explaining the present invention.

Fig. 4C shows a recording pulse pattern in the mark edge recording method according to the present invention.

Fig. 5A shows the marks recorded on the track before overwriting in the pit position recording method for explaining the prior art.

Fig. 5B shows the marks recorded on the track after overwriting in the pit position recording method for explaining the prior art.

Fig. 5C shows a recording pulse pattern in the pit position recording method according to the prior art.

Fig. 6A shows the marks recorded on the track before overwriting in the pit position recording method for explaining the present invention.

Fig. 6B shows a mark recorded on the track after overwriting in the pit position recording method for explaining the present invention.

Fig. 6C shows a recording pulse pattern in the pit position recording method according to the present invention.

7 is a flowchart of an optical disc recording method having improved cross erasure characteristics according to the present invention.

8 is a graph showing the jitter characteristic according to the overwriting cycle by the mark edge recording method.

FIG. 9 is a graph showing the cross erase jitter characteristic according to the overwriting cycle by the mark edge recording method.

10 is a graph showing the CNR characteristics according to the overwriting cycle ability by the pit position recording method.

* Detailed Description of Drawings *

1 ... disc 2 ... objective lens 3 ... beam splitter 4 ... photo detector

5 ... laser 6 ... computation circuit 7 ... channel 1 processor 8 ... channel 2 processor

9 ... control signal generator 10 ... laser pulse controller

11 substrate 12 lower dielectric layer 13 upper dielectric layer

14 ... First reflecting film 15 ... Recording film 16 ... Second reflecting film

17 ... Reading pulse 18 ... Pulse train 19 ... Off pulse

Claims (8)

In the recording apparatus of a phase change optical disk drive comprising a pickup, a recording / reproducing signal processing unit, a servo unit, and a control unit including a laser, which can be overwritten, The control unit In the recording mode, the recording / reproducing signal processor compares the reproduction signal reproduced on the track to be recorded with the modulated recording signal to be recorded, so that the first control signal when only the reproduction signal has a recording mark and the recording signal has no recording mark A control signal generator for generating a second control signal when both signals do not have a recording mark and a third control signal when the recording signal has a recording mark; And When the first control signal is applied, the laser generates a first erasing level of power. When the second control signal is applied, the laser generates a second erasing level of power lower than the first erasing level. And a laser pulse controller configured to control the power of the laser so that the laser generates a predetermined multi-pulse power when the third control signal is applied. Disc burner. The optical disc recording apparatus of claim 1, wherein the recording method of the recording device of the optical disc drive is a mark edge recording method. The optical disc recording apparatus of claim 1, wherein the recording method of the recording device of the optical disc drive is a pit position recording method. The optical disc recording apparatus of claim 1, wherein the power of the second erasing level is set to 0 mW or more and less than the reproduction power. In the recording method by the laser power of the recordable / playable optical disc drive, (a) determining whether the optical disc drive is in a recording mode; (b) when the determination result of the step (a) is in the recording mode, comparing the pattern recorded in the track to be recorded with the pattern to be recorded to determine whether the erase area overlaps; And (c) As a result of the determination of step (b), when the pattern to be recorded is an erasing area and the recorded pattern is an area with a recording mark, the laser generates a predetermined first erasing power, and the recorded pattern And generating a second erasing power lower than the first erasing power when all of the patterns to be recorded are erase regions. 6. The optical disc recording method according to claim 5, wherein the recording method is a mark edge recording method. 6. The optical disc recording method according to claim 5, wherein the recording method is a pit position recording method. 6. The optical disc recording method of claim 5, wherein the second erasing power in step (c) is set to 0 mW or more and less than the reproduction power.