KR20000019292A - Apparatus and method for recording re-recordable optical disk - Google Patents

Abstract

PURPOSE: An apparatus and method for recording a re-recordable optical disk is provided, which improves a cross-erase in a land/groove recording and reproducing method. CONSTITUTION: The apparatus for recording a re-recordable optical disk comprises: a control unit (140) for reading a mark and a space of a reproducing signal reproduced from a recording track and generating an optical output level to a mark and a space of a recording modulation recording signal according to the read mark and space; and a pick-up (120) for converting a sum/subtraction value of the optical output level set in the control unit (140) and a reflected optical signal level into a current signal, and adjusting a laser output. Thereby, it is possible to improve a cycle ability in an overwriting track.

Description

Rewritable Optical Disc Recording Apparatus and Method

The present invention relates to a signal recording apparatus and method for a rewritable optical disc, and to a rewritable optical disc recording apparatus and method for improving cross-erase in a land / groove recording and reproducing method. It is about.

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, technologies related to optical discs capable of recording and reproducing high-density information such as DVD (Digital Versatile Disc) and RAM (Random Access Memory) are actively progressing in relation to recording and reproducing video information of a multimedia or high quality TV level. In response to the advent of the next-generation multimedia market, there is a need for the development of high-density optical disc media that provides further improved capacity.

In order to manufacture a high density optical disc, recording density per unit area must be increased. One way to increase the recording density is to reduce the size of the laser spot. Since the size of the laser spot is proportional to the wavelength λ of the light beam and inversely proportional to the numerical aperture, 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 disc, an optical disc having a structure in which information can be recorded on each of lands and grooves formed in the optical disc has already been proposed.

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

In the disc drive using such a high density phase change optical disk as a recording medium, the conventional recording pulse pattern according to the recording state of the track before and after overwriting in FIGS. 1A and 1B is shown in FIG. Are 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 the data recorded in the adjacent land area is erased by the heat generated in the recording section of the overlapping area before and after overwriting, and the data of the groove area is overwritten several times. There was a problem of decreasing the reliability of.

SUMMARY OF THE INVENTION A technical problem to be solved by the present invention is an optical recording medium in which information is recorded and reproduced by a change in light reflectance. When overwriting a portion in which data is recorded, previously recorded information is read in advance to adjust recording power. To provide an optical disc recording apparatus and method.

1A to 1C show a recording pulse pattern in a general phase change optical disk.

2 is an optical disc recording and reproducing system according to the present invention.

3 is a conceptual diagram showing an embodiment of the recording signal processing according to the present invention.

4A to 4C are timing diagrams showing an embodiment of the recording signal processing according to the present invention.

FIG. 5 illustrates an overwriting cycle vs. jitter characteristic graph according to the present invention and prior art.

Figure 6 shows an overwriting cycle versus cross erasure jitter characteristic graph according to the present invention and the prior art.

In order to solve the above technical problem, the present invention provides an optical disk recording apparatus,

A control section which reads a mark and a space of a reproduction signal reproduced in a track to be recorded, and generates an optical output level for the mark and space of a modulated recording signal to be recorded according to the read mark and space;

And a pickup unit for converting the light output level set by the control unit and the added or decreased value of the reflected optical signal level into a current signal form to adjust the laser output.

In order to solve the above technical problem, the present invention provides an optical disk recording method,

Outputting a reproduction signal in which the disc information signal and the recording signal are mixed;

Extracting a disc information signal by feeding back an output signal from the disc signal and removing a recording signal included in the reproduction signal;

A rewritable optical disc recording method comprising the step of recording on a disc by varying the recording power according to the mark and space combination of each of the disc information signal and the recording signal to be recorded, which are extracted in the above process.

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

The optical disc recording / reproducing apparatus of FIG. 2 includes a pick 120, a recording / reproducing signal processor 130, and a controller 140.

The pick-up 120 includes an objective lens 121, a collimate lens 122, a diffraction grating 123, a beam splitter 125, a laser diode driver 124, and a photo detector 126. The reproduction signal processor 130 corresponds to a known DSP (Digital Signal Processor) processing block, and the controller 140 includes a control signal generator 142 and a laser pulse controller 144.

After the track to be recorded on the disk 110 in the recording mode is searched, the light generated by the laser diode 124 is input to the photodetector 126 through the objective lens 122 and the beam splitter 125.

In other words, the laser beam is divided by the diffraction grating 123 into three beams of order 0 and order 1 and focused on the recording film of the disk 110. At this time, the zero-order light is used for recording, one of the primary lights reads a previously recorded disk signal and is input as a light amount control signal, and the other primary diffracted light is used for accurate recording reading. The position and intensity of each diffracted light in the diffraction grating 123 are controlled by the slits spacing, angle, and width within, and may be located on the same track or on another adjacent track.

The photo detector 126 converts an 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 by the recording / reproducing signal processing unit 130 to separate the signal for processing, the control signal for tracking and the control signal for focus control. And print it out.

The control signal generator 142 inputs a reproduction signal input through the recording / reproducing signal processor 130 and a modulation recording signal modulating a signal to be recorded, and analyzes and compares the input signal to form a recording mark, that is, a pit. It is determined whether or not it corresponds to an area or an erase area in which no pit is formed to generate recording control signals for recording on the disc.

The laser pulse generator 144 generates a write pulse as shown in FIG. 4C according to a write control signal applied from the control signal generator 142 to control the flow of current in each channel with respect to the write pulse. The control signal is applied to the laser diode driver 350.

The laser driver 124 adjusts the laser output through a laser diode (not shown) by converting the light output level generated by the controller 140 and the added and subtracted values of the reflected light signal level into a current signal form.

Referring to the conceptual diagram of FIG. 3, the signal processing performed by the controller 140 will be described below.

As shown in the conceptual diagram of Fig. 3, the laser signal for recording information on the disc is a recording signal subjected to primary modulation (Fig. 4 (b), i.e., on the disc already read by the user data and the first diffracted light). And a disc information signal (playback signal: (a) of FIG. 4) recorded in the above.

At this time, the recording signal is input in the form of a tear drop of the recording mark generated due to the DC power and a pulse having a period of Tw for signal separation. When reading an existing signal recorded on a disc, the outputs produced by the disc are a mixture of a write signal modulated for recording and a disc information signal. The subtractor 310 shown in FIG. 3 subtracts the recording signal fed back to the first diffracted light output to the signal output from the disc in the subtractor 310 to separate only the disc information signal from these disc outputs. That is, since the signal on the disk is a minimum 6Tw frequency signal and the recording signal is a 1Tw frequency signal, it can be separated. The information signal recorded on the separated disk is input to the secondary modulator 320 with a time difference corresponding to the distance between the 0th order light and the first diffraction light and modulated with the recording signal (Fig. 4 (c)). .

4A to 4C are timing diagrams for forming a recording signal to be recorded on a disc performed by the control unit 140.

For example, in the phase change recording, Fig. 4A shows a disc reproducing signal in the recording state of the disc before overwriting, where the high voltage portion is the space S where the crystalline portion is and the low voltage portion is the amorphous mark M portion. to be. 4 (b) is a recording signal which is in a state to be written to the disk after overwriting, the high voltage portion is the mark M portion where the amorphous portion and the low voltage portion is the crystalline space S portion.

The reproduction signal (a) and the recording signal (b) of FIG. 4 are compared by the control signal generator 142 to compare the high voltage portion of the recording signal with the low voltage portion of the reproduction signal, the low voltage portion of the recording signal, and the high value of the reproduction signal. Since the voltage portion has the same crystal state before and after writing, it is sufficient to maintain the state without applying heat. However, in the case of amorphous marks, adverse effects such as recrystallization due to heat of adjacent parts due to high thermal conditions for making amorphous in phase change recording may occur. In addition, in order to make an amorphous mark, since the absorption rate is different in the amorphous state and the crystalline state, the recording power applied according to the initial state must be different as shown in FIG. 4C (Pw, c and Pw, a).

That is, when the erased portion before overwriting and the erased portion at overwriting overlap, the portion (a portion) generates a first control signal that causes a recording pattern to be generated at or below the reproduction power. If only the reproduction signal has a recording mark and the recording signal has no mark (part b), a second control signal is generated. If the reproduction signal has no recording mark and only the recording signal has a recording mark (c portion), the third control signal is generated. If the reproduction signal has a recording mark and the recording signal also has a recording mark (d portion), Generate a fourth control signal. In this case, the laser pulse controller 144 controls the power of the laser diode 124 according to the control signals generated by the control signal generator 142. That is, when the first control signal is applied, the power Pr of the first erasing level shown in FIG. 4C is generated by the laser diode 124, and when the second control signal is applied, When the third control signal is applied, the second control level power Pe is generated by the laser diode 124. When the third control signal is applied, the fourth control signal generates the recording power Pw, c of the multi-pulse for forming the pit, which is the recording mark. When it is applied, the recording power Pw, c is controlled to be generated in the diode 124.

If the power Pr of the first erasing level is set below the reproduction power, the portion where the erase portion before overwriting overlaps with the erase portion at overwriting does not have a thermal effect on the adjacent track during overwriting.

5 and 6, the existing 2.6GB DVD-RAM standard pattern is compared with the recording method of the present invention.

In the case of the disc, the lower dielectric film ZnS-SiO / recording film GeSbTe / the upper dielectric film ZnS-SiO / first reflective film Cu / second reflective film ZnS- was sputtered on a polycarbonate substrate having a diameter of 120 mm, a thickness of 0.6 mm, and a track pitch of 0.595 μm. The 5-layer structure of SiO was produced. The recording and reproducing apparatus uses a light source with a wavelength of 635 nm and an objective lens with NA = 0.6, and the first diffraction beam is positioned on the same track as the zero order diffraction beam. In the first recording, the distance time between two beams was recorded according to the conventional method. The recording and reproduction is 8.2 m / sec, and the minimum recording mark is 0.42 m. The pulse width of the recording signal at the time of recording was 0.5Tw (1Tw = 17.14nsec).

As can be seen from Figs. 5 and 6, since only the proper power and the required energy are applied according to the state recorded on the disc, not only the cycleability (overwrite jitter) but also the thermal effect between adjacent tracks is improved, thereby improving cross-ease. do.

As described above, according to the present invention, in a portion where the erase portions before and after overwriting overlap, the laser power is lowered and recorded at a level below the reproduction power, so that the cross affects the signals of adjacent tracks due to the thermal effect during recording. Not only can you improve the erasure effect, you can also improve the cycleability on the overwriting track.

Claims (6)

In the optical disk recording apparatus, A control section which reads a mark and a space of a reproduction signal reproduced in a track to be recorded, and generates an optical output level for the mark and space of a modulated recording signal to be recorded according to the read mark and space; And a pickup unit which converts an acceleration / decrease value between the light output level set by the controller and the reflected light signal level into a current signal form to adjust the laser output. The method according to claim 1, wherein when the reproduction signal has no recording mark and the recording signal has a mark, a first control signal corresponding to a recording multi-pulse power of a predetermined level is generated. If the reproduction signal does not have a recording mark and the recording signal has a mark, a second control signal corresponding to a recording pulse power of the same or different level than the first control signal is generated. When the reproduction signal has a recording mark and the recording signal does not have a mark, a third control signal corresponding to an erase pulse power having a level lower than that of the second control signal is generated; And a fourth control signal corresponding to a reproduction power of a level lower than the third control signal when the reproduction signal has no record mark and the record signal has no mark. 2. The rewritable optical disc recording apparatus as claimed in claim 1, wherein the reproduction signal reproduced in the track to be recorded is led to a beam other than a recording beam. 2. The rewritable optical disc recording apparatus as set forth in claim 1, wherein the control unit sets a portion where the erased portion before overwriting and the erased portion at overwriting overlap with the reproduction power or less. In the optical disc recording method, Outputting a reproduction signal in which the disc information signal and the recording signal are mixed; Extracting a disc information signal by feeding back an output signal from the disc signal and removing a recording signal included in the reproduction signal; And recording on the disc at different recording powers according to the mark and space combination of each of the disc information signal and the recording signal to be recorded. 6. The rewritable optical disc recording method according to claim 5, wherein said recording signal and said disc information signal are separated by a frequency difference of a high frequency recording signal during recording.