JP2000163748A - Information recording system and information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent reproduction characteristics by a PRML reproduction system by making the conditions of irradiation light different according to a reproduction system which reproduces recorded information from marks formed on a recording medium. SOLUTION: Recording data 202 synchronized with a recording clock are inputted to a mark/space length decision part 203 to decide mark length and space length, a light source drive signal pattern conforming with a rule set in a memory 204 is selected, and a multipulse generation part 205 outputs a drive signal 206. The erasure power level and multipulse conditions of the drive signal are selected according to recording condition rules, but they are made different according to thermal condition of, needless to say, recording density, recording line density, and whether a recording track is between guide grooves (land) or in a guide groove (groove) and a reproduced signal processing system as a premise. Those recording condition rules are set in the memory with condition information 207 from a controller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording method for recording information by forming a mark by irradiating a recording medium with light, and recording information using the information recording method. The present invention relates to an information recording / reproducing device capable of reproducing information.

[0002]

2. Description of the Related Art In an optical recording medium which irradiates light onto a recording medium to form a discernable mark by generated heat, for example, in a phase change type optical disk, the start and end positions of the mark correspond to information to be recorded. Pulse Width Modula
The Option (PWM) method is effective for increasing the density.

In general, in the PWM method for an optical disk, in order to reduce a heat storage effect caused by laser irradiation, when recording a long mark, multi-pulse recording divided into a plurality of pulses instead of a single pulse is performed. FIG. 6 shows an example of multi-pulse recording. When information is recorded by the 8/16 modulation code, the mark length to be recorded has a discrete value of 3T to 14T with respect to the recording window width T. The shortest mark, 3T, is recorded by a single 1.5T pulse, but a mark longer than 4T is longer than 3T by an amount equal to the erasing power period of 0.5T after the 1.5T pulse and 0.5T pulse. Recording is performed by repeatedly providing a recording power period. Therefore, these pulses may be generated in synchronization with the recording clock. The figure shows a case where marks of 3T and 6T length are recorded.

However, even if such multi-pulse recording is performed, the start and end positions of the formed mark change depending on the length of the mark to be recorded. When the recorded information is reproduced by the level slice binarization method of the reproduced signal, such a fluctuation in the start and end positions of the mark causes a jitter, thereby deteriorating the information recording reliability. The inventor has proposed a recording compensation method that changes the recording light intensity according to the length of a mark to be formed, or a recording compensation method that shortens the width of an optical pulse more than the difference in the length of the mark to be formed when the mark to be formed is short. Method has already been proposed.
No. 105970).

On the other hand, as the recording density increases, the Partial Response Maximum Likel
The ihood (PRML) reproduction method is more advantageous for low error reproduction. However, since the PRML reproduction method uses linear operation of the reproduction signal waveform, the conventional recording method that prioritizes the positional accuracy of the start and end of the mark has a large error in the linear operation of the reproduction signal waveform, and No good reproduction performance can be obtained.

[0006]

As described above, the conventional information recording system cannot obtain sufficient performance of the PRML reproduction system which is advantageous for low error reproduction at the time of high density recording.
The present invention relates to an information recording system capable of obtaining good reproduction characteristics by the PRML reproduction system, and an information recording / reproduction capable of recording information using the information recording system and reproducing the information. It is intended to provide a device.

[0007]

In order to achieve the above object, according to the present invention, a recording medium is irradiated with light according to conditions corresponding to information to be recorded, and an identifiable mark is formed on the recording medium. In the information recording method, an information recording method is provided in which the condition of light to be irradiated is changed according to a reproduction method for reproducing information recorded from a mark formed on the recording medium.

Here, the light to be irradiated when forming the mark may be constituted by a number of pulses corresponding to the length of the mark. Also, if the reproduction method is PR
In the case of the ML reproduction method, it is preferable that the time interval of the first pulse among the pulses for forming the mark is set shorter than that in the case of the level slice binarization method.

Further, in these information recording systems, the condition of the light to be irradiated may be compensated for according to the length of the mark or the interval between the marks. In order to achieve the above object, according to the present invention, in order to form an identifiable mark on a recording medium, irradiation means for irradiating light in accordance with conditions according to information to be recorded, and the formed mark An information recording / reproducing apparatus, comprising: selecting means for selecting a reproducing method for reproducing information recorded from the apparatus; and control means for controlling a condition of light to be applied according to the selected reproducing method, and Irradiating means for irradiating light in accordance with a condition corresponding to information to be recorded to form an identifiable mark on a recording medium; determining means for determining the type of the recording medium; Control means for controlling the conditions of the light to be irradiated by the controller, and selecting means for selecting a reproducing method for reproducing the information recorded from the formed mark based on the information of the determining means. To provide an information recording and reproducing apparatus according to claim.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a configuration diagram of an embodiment of an information recording / reproducing apparatus according to the present invention. The recording medium is, for example, a rewritable optical disk 101 having a phase-change recording film. The recording data 103 synchronized with the recording clock 102 is transmitted to a power controller (control means).
It is input to 104. A light source (for example, a semiconductor laser) 105 is controlled by the power controller 104 in accordance with the recording data 103, and light having a pattern and intensity corresponding to the recording data 103 is emitted from the light source 105 and irradiated on an optical disc, thereby forming a recording mark. It is formed. The mark recorded on the optical disk is
06, a change in the amount of reflected light is detected, and a signal corresponding to the amount of reflected light is output from the reproduction system (107) to the reproduction signal 10
8 is output.

FIG. 2A is a block diagram showing the configuration of the power controller 104. The input data is a binary signal according to the PWM reproduction method. The “H” section corresponds to a mark on the optical disc, and the “L” section corresponds to a space. Recording clock 2
01 is input to the mark / space length discriminating unit 203, the mark length and the space length are discriminated, and a light source driving signal pattern according to the rules set in the memory 204 is selected. Generation unit 205
Outputs a drive signal 206. FIG. 2B shows the relationship between the recording data and the drive signal. In the “H” section of the recording data, by selecting a multi-pulse pattern including the length or the immediately preceding and following “L” section length as a condition, the section where light is irradiated on the optical disc is in an amorphous state. To form a mark. On the other hand, in the “L” section of the recording data, by selecting an erasing power level (constant value), a space is formed on the optical disk in a state where the light is irradiated in a crystalline state.

The erasing power level of the drive signal and the multi-pulse conditions (the peak value and the width of each divided pulse on the condition of the mark length and the space length) are in accordance with the recording condition rules set in the memory of FIG. These are selected, not to mention the characteristics of the recording medium, as well as the recording density, the recording linear velocity, the thermal conditions such as whether the recording track is between the guide grooves (lands) or in the guide grooves (grooves), and the reproduction signal processing assumed. Different depending on the method. These recording condition rules are set in the memory by the condition information 207 from the controller.
Here, the reason for making the recording conditions different depending on the reproduction signal processing method, in particular, is that according to the study of the inventor, for example, the case where the recording information is reproduced by level slice binarization of the reproduction signal and the case where the reproduction information is reproduced by the PRML signal processing And
This is because conditions required for obtaining good reproduction characteristics are different.

Here, the level slice binarization method and the PR
The ML reproduction method will be described. In the case where information is recorded by forming a record mark array on an optical disc using a DVD-RAM or the like, information is reproduced by detecting the start position and end position of each record mark. Actually, the reproduction signal is the reflected light amount obtained by scanning the mark array with the light spot, but the mark boundary position becomes unclear because the light spot is a finite circle. In the level slice binarization method, a signal level threshold is set, and this is determined as a mark boundary. However, if the recording density is improved without changing the light spot size, the waveform interference with the preceding and following marks will increase in places where the mark length or mark interval is short, and the signal amplitude will decrease. Displacement is likely to occur. In the case of the level slice binarization method, it is general to perform a waveform equalization process for emphasizing a high frequency component of a reproduction signal for the purpose of compensating for waveform interference. I am worried about the characteristics of density.

On the other hand, in the case of the PRML reproduction method, for example, in the PR (1,2,2,1) ML reproduction method, the reproduction signal waveform is formed into a shape having a ratio of 1, 2, 2, 1 in four continuous channels. Equalize. Therefore, since the signal level of each channel after equalization is the sum of the previous and next mark states, the original data cannot be restored by that channel alone. However, the most probable original data is determined from the level transition between channels. . Since PR equalization has a shape that allows waveform interference,
Noise enhancement accompanying equalization is small, and is an effective method for higher density recording.

In either reproduction method, there is no problem as long as the marks of each length in the recorded mark row are formed in an ideal shape. However, since the optical disc is of the thermal recording type, the recorded mark has a shape distortion due to thermal interference. In particular, for higher density recording,
Because the degree of thermal interference varies depending on the recording mark length,
The shape distortion is different. Therefore, the recording condition is changed to compensate for this. However, as described above, in order to secure the performance in the level slice binarization method, the slice level comes to a position determined by the long and short marks. This is very important. On the other hand, in the PRML reproduction method, P
Since the original data is decoded from the signal level-added by R equalization, it is important that the waveform has linearity with long and short marks, and the emphasis is different from the level slice binarization method. come.

FIG. 3 shows a multipulse condition rule in the present embodiment. FIG. 3A shows a recording condition A on the assumption that reproduction is performed by the level slice binarization method as usual, and the head pulse width of the multi-pulse is set to 1 as in FIG. .5T. On the other hand, FIG.
(B) is a recording condition B on the assumption that reproduction is performed by the PRML reproduction method, and the head pulse width of the multi-pulse is 1.2T. That is, in recording on a recording medium reproduced by the PRML reproduction method, the head pulse width of the multi-pulse is set smaller than that in the level slice binarization method. In both conditions, the peak value is set lower than other pulses only when recording the shortest 3T length mark (normally 9.5 mW, but 9 m in the case of 3T length).
W), as described in Japanese Patent Application Laid-Open No. 10-105970, to compensate for the difference in thermal response of the recording mark length.

FIG. 4 shows the linear recording density dependence of the error rate under the recording conditions A and B. The horizontal axis indicates the bit length, and the vertical axis indicates the bit error rate (BER). here,
The used disk is an LtoH type recording medium in which the recording mark reflectivity is higher than the space portion, the recording track is in a guide groove (groove), and the relative moving speed between the medium surface and the light spot in recording / reproducing is 6 m. / S, changing the recording clock (the reciprocal of the window width T) was measured. When the reproducing method is the level slice binarizing method in FIG. 4A, the recording condition A is better than the recording condition B, and the reproducing method is PRM in FIG.
On the other hand, in the case of the L reproduction method, it is understood that the recording condition B is better than the recording condition A. That is, the recording condition A is used for recording on the assumption that reproduction is performed by the level slice binarization method, and the recording condition B is used for recording on the assumption that reproduction is performed by the PRML reproduction method. With this setting, highly reliable information recording / reproducing can be performed in either reproducing method.

In the embodiment described above, as shown in FIG. 3, the recording condition and the PR for the level slice binarization method are used.
The case where only the leading pulse width is different from the recording conditions for the ML reproduction method has been described. However, the condition for obtaining good reproduction characteristics in the level slice binarization method is the start and end position accuracy of the mark, and the condition for obtaining good reproduction characteristics in the PRML reproduction method is linearity of the reproduction signal waveform. Therefore, the present invention can be implemented even if the multi-pulse condition rules in the recording conditions for both types are not similar. In particular, when performing high-density recording / reproducing with the PRML reproducing method and when performing relatively low-density recording / reproducing with the level slice binarization method, not only the difference in the method but also the thermal condition due to the difference in the recording density described above. Is taken into account, the recording conditions of both may be significantly different, including the recording compensation method. In the case where both the recording methods and the recording density are made different between the two reproducing methods, a difference in conditions due to a difference in medium characteristics is further taken into account. In this embodiment, the case where the modulation method is 8/16 modulation has been described.
There is no problem in applying the present invention to other modulation schemes such as (1, 7) RLL modulation as long as recording conditions are set correspondingly.

Next, another embodiment of the information recording / reproducing apparatus according to the present invention will be described. FIG. 5 shows a configuration diagram of another embodiment of the information recording / reproducing apparatus according to the present invention. In addition,
The same components as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In this embodiment, level slice 2
Two reproduction systems A and B are provided in order to enable reproduction by two types of systems, namely a binarization system and a PRML reproduction system.
Further, there is provided a selection means 109 for selecting one of the methods according to the type of recording medium used for recording and reproduction. Hereinafter, the recording and reproducing procedures in the present embodiment will be described.

First, at the time of recording information, the recording medium 101
Either the level slice binarization method or the PRML reproduction method is determined based on a signal from the determination means 110 for determining the type of. Based on this information, the power controller 104
In this case, for example, the multi-pulse condition rule (recording conditions A and B) shown in either FIG. 3A or FIG. 3B is selected, and the light emitted from the light source is controlled based on the selected rule. Here, as the means 110 for determining the type of the recording medium, for example, a means for detecting information on the type of the recording medium which is recorded in the recording medium 101 in advance as information is used.

When reproducing information, the discriminating means 1 is used.
The information of No. 10 is input to the selection means 109, and a reproduction system of the level slice binarization method or the PRML reproduction method is selected.

As described above, in the information recording / reproducing apparatus according to the present embodiment, the multi-pulse condition rule is selected according to the type of the recording medium, so that recording suitable for the reproducing method can be performed. By selecting a reproduction system corresponding to the system, it is possible to obtain good reproduction characteristics.

[0024]

As described above, according to the present invention, P
Provided is an information recording method capable of obtaining good reproduction characteristics by the RML reproduction method, and an information recording / reproducing apparatus capable of recording information using the information recording method and reproducing the information. It is possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of an information recording / reproducing apparatus according to the present invention.

FIG. 2 is a configuration block diagram of a power controller.

FIG. 3 is an explanatory diagram of a multi-pulse condition rule (recording conditions A and B).

FIG. 4 is a diagram showing a linear recording density dependency of an error rate compared under recording conditions A and B.

FIG. 5 is a configuration diagram of another embodiment of the information recording / reproducing apparatus according to the present invention.

FIG. 6 is an explanatory diagram showing an example of conventional multi-pulse recording.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Optical disk 102 Recording clock 103 Recording data 104 Power controller 105 Light source 106 Optical receiver 107 Reproduction system 108 Reproduction signal 201 Recording clock 202 Recording data 203 Mark / space length discrimination part 204 Memory 205 Multi-pulse generation part 206 Drive signal 207 Condition information

Claims (6)

[Claims] An information recording method for irradiating a recording medium with light in accordance with conditions according to information to be recorded and forming an identifiable mark on the recording medium, wherein information is recorded from the mark formed on the recording medium. An information recording method characterized in that conditions of light to be irradiated are changed according to a reproducing method for reproducing the reproduced information. 2. The method according to claim 1, wherein the light irradiated when forming the mark is:
2. The information recording method according to claim 1, wherein the information recording method comprises a number of pulses corresponding to the length of the mark. 3. When the reproducing method is the PRML reproducing method, the time interval of the first pulse among the pulses for forming the mark is made shorter than in the case where the reproducing method is the level slice binarizing method. 3. The information recording method according to claim 2, wherein: 4. The information recording method according to claim 1, wherein conditions for light irradiation are compensated for according to a length of the mark or an interval between the marks. 5. An irradiating means for irradiating light according to a condition corresponding to information to be recorded to form an identifiable mark on a recording medium, and reproducing to reproduce information recorded from the formed mark. An information recording / reproducing apparatus comprising: selecting means for selecting a method; and control means for controlling conditions of light to be applied according to the selected reproducing method. 6. An irradiating means for irradiating light according to a condition corresponding to information to be recorded to form an identifiable mark on a recording medium; a discriminating means for discriminating a type of the recording medium; Control means for controlling the condition of light to be radiated based on the information of the means, and selecting means for selecting a reproduction method for reproducing the information recorded from the formed mark based on the information of the determination means. An information recording / reproducing apparatus characterized by having: