JP3345932B2 - Optical disk device and optical information recording / reproducing method - Google PatentsOptical disk device and optical information recording / reproducing method
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- JP3345932B2 JP3345932B2 JP00388793A JP388793A JP3345932B2 JP 3345932 B2 JP3345932 B2 JP 3345932B2 JP 00388793 A JP00388793 A JP 00388793A JP 388793 A JP388793 A JP 388793A JP 3345932 B2 JP3345932 B2 JP 3345932B2
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- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/0062—Overwriting strategies, e.g. recording pulse sequences with erasing level used for phase-change media
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording apparatus by optical recording and a medium used for the information recording apparatus.
2. Description of the Related Art With the recent development of a highly information-oriented society, the need for a large-capacity and high-density file memory is increasing. Optical recording has attracted attention as a response to these problems, and a read-only type, a write-once type, and a rewritable type are sequentially commercialized, and are used for applications that make use of the features of each. Of these, rewritable magneto-optical recording has recently been commercialized. At present, research and development are being pursued by many research institutions with the aim of commercializing next-generation magneto-optical recording. One of the centers of research on commercialization is ultra-high density recording. As means therefor, there have been proposed techniques such as reducing the track pitch, shortening the recording magnetic domain interval, using light having a short wavelength, or giving information to the edge portion of the recording magnetic domain, and it is effective to use these together. It is believed that.
An optical disk device is one of means for recording a digital signal on a recording medium. In an optical disk, a laser beam is focused on a recording surface by a lens, the intensity of which is changed according to the information to be recorded, and the reflectivity of the recording film in an area irradiated with the laser beam, or in the case of magneto-optical recording. Is to record information by changing the magnetization direction by external magnetization or the like. When reproducing recorded information, a laser beam of weaker intensity than that at the time of recording is irradiated, and the change in the amount of light from the reflected light from the recording film or the polarization plane rotation due to the difference in the magnetization direction is detected. Do. The recording density is mainly determined by the size of the spot of the laser beam focused on the recording surface, and the size is about 1 μm at present.
m, so that high-density recording about 10 times that of a magnetic disk can be realized.
A mark length recording system in which information is recorded at positions before and after a recording mark recorded by modulating the irradiation light power is used because two or more data are recorded on one recording mark. This is an effective means for realizing high-density recording.
As described above, in the mark length recording method for recording and reproducing information on an optical disk at high density, various signal processings are performed at the time of recording and reproducing data in order to realize high reliability of information. .
For example, generally, when the irradiation light power at the time of recording is small, the shape of a recording mark formed tends to be unstable.
Further, if the recording linear velocity is different, the amount of heat applied per unit area and the heat distribution are changed, so that the recording mark shape is different. Therefore, in order to actually perform recording and reproduction by forming a stable recording mark shape, "application of pit edge recording to a PbTbSe film" (Proceedings of the 70th Anniversary of the IEICE, p4-176) In, the recording irradiation light pulse is set to be relatively large, and the laser pulse length is shortened during recording so that the mark length does not become longer than the target value in accordance with the linear velocity, or the pulse length of the binarized signal is reproduced during reproduction. We make adjustments such as shaving.
In general, the shape of a recorded mark mainly depends on the recording sensitivity and thermal conductivity of the recording medium, the intensity distribution of a focused laser beam used for recording, the wavefront aberration, and the like. When the combination of the recording medium and the recording medium changes, the characteristics change. Furthermore, the level of the irradiation light power at the time of recording on the apparatus side changes with time. This phenomenon is inevitable in a certain range of fluctuation even when an automatic laser power control mechanism (APC) is provided, and the recording / reproducing characteristics also fluctuate due to this factor. This change leads to a change in the recording mark length during recording and a change in the pulse interval of the reproduced signal during reproduction.
For this reason, when the recording correction amount and the recording light power are set to fixed values in advance at the time of shipment of the apparatus, these setting specifications are obtained by measuring the recording / reproducing characteristics with a number of combinations of recording media and recording apparatuses. decide. then,
In consideration of the variation range of the recording / reproducing characteristics due to the difference of the combination, in order to guarantee the reliability at the time of detection in all cases, a large margin is provided for the recording density, and the recording density is sacrificed.
Therefore, in order to absorb the variation in characteristics due to the combination of the recording medium and the recording device, and to increase the recording density, a test pattern is recorded in advance, and information for adjusting recording conditions is obtained from the reproduced signal. A method has been proposed. For example, in the apparatus described in JP-A-61-239441, the irradiation light power level, which is a constant value during recording, is set to
In the apparatus described in Japanese Patent Application Laid-Open No. 1-74178, a constant adjustment amount relating to the recording pulse width is adjusted, and in the apparatus described in Japanese Patent Application Laid-Open No. 63-304427, both of them and the automatic equalization coefficient during reproduction are adjusted simultaneously.
Further, since the optical disk is basically a recording method using thermal diffusion, a phenomenon in which the shape of a recording mark changes due to the diffusion of heat distribution due to a plurality of recording pulses before and after the recording mark (hereinafter, referred to as heat). Interference). This phenomenon also leads to variations in the pulse interval of the reproduced signal during reproduction. Therefore, it is necessary to consider the influence of the thermal interference in order to perform the optimum correction at the time of recording. As a countermeasure, in the recording method described in JP-A-63-48617, the width of each recording pulse is changed in accordance with the interval to the immediately preceding recording pulse.
A conventional recording method is disclosed in Japanese Patent Application Laid-Open No. Hei 3-22223.
As described in the publication, a recording code train of a recording mark is pulsed to form a series of pulse trains corresponding to the length of the recording code train, and the length and amplitude of the pulse train are recorded immediately before the recording code train. In this method, control is performed in accordance with the length of the reverse phase of the train, the pulse train is divided into three parts, and recording is performed by changing the pulse width of each pulse.
As for the recording density in the radial direction, the track on the disk is divided into zones composed of a plurality of tracks. In the medium, it is already Japanese Patent Application No. 2-
133819. However, in this case, the linear density in each zone on the disk cannot be made constant due to the recording / reproducing characteristics of the write-once film, and the recording linear density in the zone on the inner circumference of the disk becomes smaller in the zone on the outer circumference. It is higher than the linear density.
The above prior art does not take into account the fact that the recording sensitivity varies with respect to the recording medium due to the variation in the thickness of the recording medium or the variation in the environmental temperature. There was a problem to cause.
In addition, of the above prior arts, the following recording pulse width adjusting method according to the interval up to the immediately preceding recording pulse has the following problems.
That is, when high-density recording is aimed at such that the recording mark shape and the interval between the recording marks are equal to or smaller than the size of the laser spot converged on the recording film surface, the thermal interference of the optical disk is reduced. Is greater than the shortest recording mark length. In other words, when determining the edge position of a certain recording mark, the length of a plurality of recording pulse intervals of the recording irradiation light pulse has an effect due to heat diffusion, and as a result, a recording pulse of the same length is irradiated. However, the edge position changes due to the combination of the recording patterns located earlier in time. In particular, in the case of a recording medium having a high recording sensitivity with respect to the intensity of laser light and capable of recording with a low laser power, the thermal conductivity is generally large, and the range affected by the thermal interference is large.
Further, in this recording pulse width adjustment method, since the information on the adjustment amount uses a preset value regardless of the recording condition at that time, the adjustment amount relating to the fluctuation of the recording characteristics can be changed. However, as the recording characteristics deviate from those at the time of setting, errors appear in the adjustment, and the adjustment is not accurate.
On the other hand, in the above-described method for obtaining the information of the recording condition adjustment, the recording irradiation light power or the single amount of the recording pulse width is adjusted, and the fluctuation of the recording mark length due to thermal interference is not reduced. .
Conventionally, a linear equalizer such as a transversal filter has been generally used in the field of communication and magnetic recording as a measure against intersymbol interference components on the reproducing side. This is to reduce linear intersymbol interference generated by superimposition on a nearby waveform due to a narrow base of a reproduction signal pulse due to a narrow frequency band of the signal reproduction system.
However, the above-mentioned influence of thermal diffusion mainly appears as a waveform shift in the time direction during reproduction.
This is a non-linear intersymbol interference component that cannot be expressed simply as a linear superposition of basic waveforms according to recording information. Therefore, the edge position fluctuation component cannot be dealt with by the linear equalizer, and it is actually very difficult for the reproduction side to deal with this interference component in real time.
For the reasons described above, even if the conventional method can cope with the fluctuation of the recording characteristics, the fluctuation of the recording mark length due to the influence of heat interference cannot be reduced at all, or the recording mark due to the influence of heat interference can not be reduced. There is an adjustment error in the variation of the length, and it cannot cope with the variation of the recording characteristics at all. Particularly, in mark length recording in magneto-optical recording using a recording medium having high thermal conductivity, these fluctuation components are large, and a margin is provided for them, so that the recording density has to be greatly sacrificed.
In addition, as for the influence of heat, in order to record information at a high density using a magneto-optical recording medium, pit edge recording in which information is provided at both ends of an elliptical domain is employed. When recording is to be performed in the form of the conventional technique, since the thermal conductivity of the medium of the magneto-optical disk is good, the inner circumference where the linear velocity is low is affected by the heat of the pulse recorded immediately before, and the information domain of the information domain to be recorded next is affected. The position shifts. This makes it impossible to accurately reproduce information.
As described above, in order to realize ultra-high-density optical recording in magneto-optical recording, it is necessary to control the heat flow and accurately record at a desired position to a desired size. Must. This problem is because the magneto-optical disk responds very sensitively to temperature.
However, since optical recording is generally thermal recording, it is a problem that must be solved for all types of optical recording that can be recorded by a user, such as phase-change optical recording and write-once optical recording, in addition to magneto-optical recording.
The objects of the present invention are as follows.
The first object of the present invention is to provide a recording control method for precisely controlling the size of a recording magnetic domain, particularly the magnetic domain length and the magnetic domain width, thereby providing a magneto-optical recording suitable for ultra-high density optical recording. Is to provide a recording control method.
A second object of the present invention is to propose a recording / reproducing apparatus for performing high-density information using a magneto-optical recording medium. In particular, it is to propose an effective method for a recording method on a disk.
A third object of the present invention is to suppress recording mark fluctuations due to the recording sensitivity fluctuations as much as possible and perform highly accurate recording mark control.
A fourth object of the present invention is to improve compatibility between a recording / reproducing apparatus and a recording medium and to suppress fluctuation in recording sensitivity caused by the recording / reproducing apparatus.
A fifth object of the present invention is to improve the reliability, storage capacity and information transfer rate of a recording / reproducing apparatus.
One of the problems in realizing ultra-high-density magneto-optical recording is that both the tracks and the recording magnetic sections are clogged. That is, the recording magnetic domains formed also interfere with each other. Therefore, in order to realize ultra-high density of magneto-optical recording, the domain size must be precisely controlled.
Factors influencing the size of the magnetic domain formed include environmental temperature, variations between recording media, fluctuations in laser power, and the like. In recording or erasing, by detecting these fluctuation factors and performing recording or erasing by applying appropriate feedback, the recording density can be increased without the magnetic domains formed interfering with each other.
Usually, in magneto-optical recording, a data recording area on one disk is divided into a plurality of zones in a radial direction and a track direction. An area for obtaining information necessary for performing recording control is provided for each zone, and at least recording / reproduction is performed in this area to find a recording condition.
Here, in order to record user information, 1
Data is recorded so that the density of data to be recorded is the same in any of the zones in which the data recording area on one disc is divided into a plurality of zones in the radial direction and the track direction. As a recording method to be used, it is most preferable to perform so-called pit edge recording in which information is given to an edge portion of a recording domain.
Incidentally, in order to obtain data necessary for performing recording control, it is conceivable that a certain pattern is stored in advance in a magneto-optical disk drive, and recording / reproduction is performed using this. In an optical disc in which a data recording area of one disc is divided into a plurality of zones in a radial direction and a track direction as an area for recording / reproducing in a test, at least one track or one track in one sector is provided for each zone. It is desirable to use the entire circumference of the track as a test track for collecting various data for performing recording control.
As a method of collecting information for controlling the recording, at least one type of information selected from the magnetic domain width, the magnetic domain length, or the interval between the magnetic domains of the formed recording magnetic domains may be collected. Then, based on the information, the laser power at the time of recording, the width of the recording pulse, or the waveform of the recording pulse is controlled to record user data.
The data collection interval for the recording control is fine at least when the magneto-optical disk drive is started and when the disk is inserted, and at other times the control information may be collected more coarsely than in the previous case. This is because the information obtained here is mainly information on environmental temperature changes. Among them, the information obtained at the time of inserting the disc also includes variations in sensitivity of the disc. This allows
Media compatibility can be ensured.
Each zone has at least one in one sector.
The provision of a test track for collecting various data for performing recording control over a track or the entire circumference of one track is provided.
This is because when recording or erasing is performed under variations in the disc or at a constant rotation speed, the heat flow differs for each thorn, so that the recording conditions are different. This test track may be located at any position within one zone as long as it is representative of the characteristics of each zone. However, considering the ease of use, the first or last part of each zone or the center of the zone Is particularly preferred.
A data recording area on one disk is divided into a plurality of zones in a radial direction and a track direction,
At least one track in one sector or the entire circumference of one track in each zone is provided as a test track for collecting various data for performing recording control. By performing test recording / erasing on this track, it is possible to detect a change in the shape of the recording magnetic domain due to a change in environmental conditions or a variation between recording media. And a recording magnetic domain of the same size is obtained. By using the method of the present invention, a minute recording magnetic domain can be formed without being affected by disturbance, so that stable recording / reproduction can be performed. As a result, ultra-high density magneto-optical recording was realized.
In order to improve the compatibility between the recording medium and the recording apparatus, test writing is performed in advance at a predetermined position on the recording medium, and a reproduction signal obtained by the test writing is compared with the test writing data. After the proper result is obtained, the recording of proper information is started.
In addition, the test write data and the input data bit string of regular information are converted into a code string of a recording apparatus, and a data string for recording the code string on a recording medium is generated, and the laser light source is driven. By forming a recording area on a recording medium, accurate recording is performed. As a result, in order to improve the compatibility between the recording medium and the apparatus that performs the recording, the test writing is performed in advance at a predetermined position of the recording medium, such as a change in the film thickness of the recording medium due to the exchange of the recording medium and a change in the environmental temperature. An operation of writing a recording mark having strict conditions among recording marks to be recorded on a recording medium before recording regular information in order to detect a change in recording sensitivity to the recording medium due to a change in characteristics of a recording apparatus. do. Furthermore, the playback signal obtained from the recorded test writing data is compared with the test writing data,
In order to obtain a good result, the operation is performed so as to adapt the recording medium to the recording apparatus by changing the light intensity or energy of the recording waveform for recording. As a result, the optimum recording conditions for the recording medium can be always obtained, so that the information recording malfunction due to the above-mentioned fluctuation in the recording sensitivity is eliminated, and the recording and reproduction with high reliability can be performed.
Preferably, recording / reproducing is performed immediately after recording of the normal information or at a certain period, and the input data bit string and the output data bit string are compared.
By performing the test writing described above, reliable recording and reproduction can be performed.
Preferably, a recording pulse train and a recording auxiliary pulse corresponding to a recording mark are generated to minimize test writing performed immediately after recording of regular information or by recording / reproducing at a certain period. The length and width of the recording mark were controlled while keeping the temperature of the recording medium substantially constant using two light intensities or two energy levels for the recording auxiliary pulse.
Further, preferably, in order to accurately determine the recording state by trial writing, the quality of the recording condition is determined without improving the amplitude and frequency characteristics of the reproduction signal. is there.
Preferably, a recording pulse train and a recording auxiliary pulse corresponding to the recording mark of the input data bit string of the test writing data and the normal information are generated, and two light intensities for the recording pulse train and the recording auxiliary pulse or 2
Recorded on a recording medium using three energy levels.
Also, preferably, the present invention is applied to a recording medium and an erasing power in a recording medium capable of overwriting information by modulating the light intensity of a recording pulse train and a recording auxiliary pulse.
Preferably, immediately after recording the input data bit string of the legitimate information, reproduction is performed and the input data bit string and the output data bit string are compared.
Further, test writing is performed in advance at a predetermined position on the recording medium, a reproduced signal obtained by the test writing is compared with test writing data, and after obtaining a good result, recording of regular information is started. In doing so, the test write data and the input data bit string of the legitimate information are used as a code string of a recording device, a data string for recording the code string on a recording medium is generated, and the laser light source is driven to perform recording. In a recording waveform for forming a recording area on a medium, the light intensity or the energy level of a recording pulse train and a recording auxiliary pulse corresponding to a recording mark is controlled.
An apparatus for recording and reproducing information concentrically on a disk-shaped recording medium in an optically identifiable form, wherein the track on the disk is divided into zones consisting of a plurality of tracks, In the zone, recording is performed so that the recording linear densities are the same, and the recording linear density in the inner circumference of the disc is lower than that in the outer peripheral zone.
The linear density can be reduced on the inner peripheral side, and information can be read accurately even if there is thermal interference. On the other hand, since the contribution of the inner track to the storage capacity that can be accommodated in the entire disk is not large, even if the linear density is reduced on the inner periphery, the capacity per disk is hardly reduced and efficiently. High density can be achieved.
Based on the above findings, the present invention typically employs, as shown in FIG. 1, a light source 8 for irradiating an optical disk 1 with a light beam, an encoder 4 for converting an information signal to be recorded into a code string, and a code string. The light source driving means 7 modulates a light beam according to the above and irradiates the optical disk as an optical pulse train and records a code train as a recording mark by at least one of its thermal action or thermal interference, and photoelectrically converts light from the optical disk to an electric signal waveform. , A waveform processing means 11 for performing waveform processing on an electric signal waveform, a pulsing means 13 for converting a signal from the waveform processing means into a pulse signal, and a discrimination for detecting a code string recorded on an optical disc from the pulse signal. In an optical disc apparatus having a decoder 15 and a decoder 17 for decoding a code string from the discriminator into an information signal, a light beam is modulated by a specific test signal. It has test writing means 3 for forming a test pattern on a disk, means 16 for reproducing the test pattern and comparing it with a test signal, and control means 6 for controlling the modulation of the light beam based on the comparison result. An optical disk device characterized by controlling at least one of a power level, a pulse width, and a pulse interval of a pulse forming a pulse train.
The control of the power level can be realized by having a control means for controlling the modulation of the light beam by selecting a pulse width or a pulse interval from predetermined values.
The comparison result reflects at least one element selected from the width and length of the recording mark or the mark interval.
The test pattern from the test writing means 3 is
It is desirable that the data be encoded by the encoder 4 and then recorded in the same manner as the data.
It is more desirable to have a changeover switch 12 for inputting the electric signal waveform to the pulsing means 13 without passing through the waveform processing means 11, and to evaluate the reproduced signal of the test pattern without passing through the waveform processing means. .
One unit of an optical pulse train forming one of the recording marks is composed of, for example, a leading pulse and a succeeding pulse train having a different time width from the leading pulse. If the subsequent pulse train is a pulse train in which at least one of the pulse time width or pulse interval is equal, control becomes easy.
In a preferred embodiment of the present invention, one unit of the optical pulse train forming one of the recording marks has a pulse having a power level higher than Pw, and the optical pulse train not forming the recording mark has a power level lower than Pas. And at least one of a front side and a rear side of the optical pulse train forming the recording mark has a power level region equal to or lower than Pr.
However, Pw> Pas> Pr.
Further, one unit of the optical pulse train forming one of the recording marks may be configured to have two or more power level pulses. In one unit of the optical pulse train forming one of the recording marks, the power level of the first pulse and the power level of the subsequent pulse may be different.
The control means controls the number of pulses of one unit of light pulse train forming one of the recording marks,
Alternatively, at least one of Pw, Pas and Pr is changed.
Further, the control means determines the edge position of the pulse forming the optical pulse train based on at least one of the temperature of the optical disk, the linear velocity of the recording on the optical disk, and the combination of the recording marks based on the information signal to be recorded. It may be controlled. It may be configured to have a table for storing information for controlling the edge position.
It is desirable that the optical disc be divided into a plurality of zones having different recording conditions in the radial direction, for example, and each zone have an area for recording the test pattern.
The optical disk is divided into a plurality of zones in the radial direction, and the linear recording densities are equal in the same zone.
It is also desirable that the innermost zone of the optical disc has the lowest linear recording density. To equalize the linear recording density, it is preferable to perform recording using an optical pulse train in which at least one of the pulse width and the pulse interval is changed for each zone or according to the radial position of the disk.
The pulse width of the pulse forming the optical pulse train,
Alternatively, it is preferable that a recording clock is used to control at least one of the pulse intervals, and the width is set to an integral number or an integral multiple of a detection window width formed by the recording clock.
The light source driving means 7 includes a plurality of unit driving circuits each including a switching means and a current source in series with the switching means, one constant current source being disposed in series with each unit driving circuit, and a constant current source. The light source 8 is connected in series with the unit drive circuit and in parallel with the unit drive circuit, the current sources of the plurality of unit drive circuits are configured to flow currents of different values, and the switch means is operated by a control signal based on the code string. , Light source 8
Control the current value that drives. At least one of the current sources of the unit drive circuit can be made to have a variable current to enable control of the light pulse.
It is preferable that the switch means use an element which switches by npn type.
The information recording / reproducing method of the present invention converts an information signal to be recorded into a code string, modulates a light beam into a light pulse according to the code string, irradiates the light pulse train to a recording medium, and heats the light pulse train. At least one of action or thermal interference
A code string is recorded as a recording mark, a light from a recording medium is photoelectrically converted to obtain an electric signal waveform, the electric signal waveform is processed, a signal from the waveform processing means is converted into a pulse signal, and a pulse signal is outputted. In the optical information recording / reproducing method for detecting a code sequence recorded on a recording medium from a device and decoding the detected code sequence to an information signal, a test pattern is modulated on a recording medium by modulating a light beam by a specific test signal. Is formed, and the test pattern is reproduced and compared with a test signal.
An optical information recording / reproducing method characterized by controlling at least one of a power level, a pulse width, and a pulse interval of a pulse constituting an optical pulse train based on a comparison result.
It is desirable that the test pattern includes the longest code and the shortest code.
According to the present invention, the fluctuation of the edge position of a recording mark due to thermal interference is temporally shifted forward or backward for each edge in accordance with a combination of a plurality of recording pulses positioned before the recording pulse. Side, and record the laser with the adjusted recording pulse signal, record and reproduce a predetermined recording signal at predetermined time intervals, and from the result, the light beam intensity at the time of recording, By detecting changes in the environmental temperature and changing the light beam intensity during recording and the amount of adjustment of each edge position according to the results, there is no change in the recording mark length under any recording conditions.
High-precision information recording is performed, and more accurate recording mark edge position control for high-density recording by mark length recording can be realized.
An adjustment is made to shift the fluctuation of the edge position of the recording mark due to thermal interference temporally forward or backward for each edge in accordance with a combination of a plurality of recording pulses immediately before. By recording the laser with the recording pulse signal, it is possible to absorb the variation in the recording mark length when the recording pattern sequence is different due to the influence of thermal interference.
In response to the fact that the recording linear velocity varies depending on the recording radius, a plurality of types of adjustment amount tables are prepared in accordance with the recording linear velocity, and the adjustment amount table suitable for the linear velocity at the time of recording is used. Thus, the recording pulse can be accurately adjusted at any position on the recording medium.
Recording and reproduction are performed using a predetermined recording signal when the use of the apparatus is started, when the recording medium is exchanged, and at predetermined time intervals, and the recording signal of the reproduction signal is hit. The pulse length and the duty of the gap length corresponding to the portion other than the recording mark are detected, and the light beam intensity at the time of recording and the deviation from the set value of the recording medium temperature are extracted from the information, and according to the result, If the light beam intensity at the time of recording deviates from the set value, change the light beam intensity at the time of recording.If the temperature of the recording medium deviates from the set value, change the contents of the adjustment table or perform recording. If the adjustment can be made by changing the light beam intensity at the time, the light beam intensity at the time of recording can be changed, and the recording pulse can be accurately adjusted even when the recording conditions fluctuate over time.
As described above, it is possible to more accurately control the edge position of a recording mark in high-density recording by mark length recording.
As described above, the present invention proposes a technique for stably forming (recording) minute magnetic domains without thermal interference or the like, as the density of magneto-optical recording increases. As a method, 1) improvement of the recording pulse waveform, 2) a method of recording on a disk, and 3) test recording, and a method of obtaining recording control information by using the result are proposed. By using at least one of these methods as the magneto-optical disk device, the recording capacity can be increased. Further, by using a plurality of methods in combination, higher density recording can be performed.
(Embodiment 1) FIG. 1 shows an optical disk apparatus according to an embodiment of the apparatus configuration of the present invention. Storage medium 1 for storing information and optical head 2 and optical head 2 for realizing storage and reproduction
And a processing system for converting the reproduction signal obtained from the information into information. The storage medium 1 is rotated by a motor 109 and the recording film 1 is rotated.
01 and a substrate 102 holding it.
The optical head 2 has a built-in optical system for focusing the light emitted from the laser 8 on the recording medium 1. At the time of recording information, the input data bit string (information)
The recording code sequence output from the encoder 4 is guided to a recording waveform generator 5, the recording waveform obtained by the recording waveform generator 5 is input to the APC 6, and light having an intensity corresponding to the recording code sequence is generated. Output from laser 8.
At the time of reproducing information, the light reflected from the recording medium 1 is guided to the optical receiver 9 by an optical system and converted into an electric signal. The signal is input to a reproduction amplifier 10 and output to a waveform processing circuit 11 such as a waveform equalizer and an input switch 12. The input switch 12 outputs a reproduced signal from either the reproducing amplifier 10 or the waveform equalizer 11 to the shaper 13 in accordance with the test writing command signal, and converts the signal into a pulse signal indicating the presence or absence of the signal. The pulse signal is guided to the discriminator 15 and the PLL 14. The synchronization signal (signal synchronized with the basic period of the pulse signal) output from the PLL 14 is input to the discriminator 15. The discriminator 15 generates a detection code string from the pulse signal and the synchronization signal, and outputs a data bit string (information) by the decoder 17. The detection code string of the discriminator 15 is output to the comparator 16.
Next, the test writing operation will be described. Test writing data from the test writing device 3 that operates according to the test writing command signal is input to the encoder 4 and converted into a recording code string. In the evaluation of the test write data recorded on the recording medium 1 via the same path as the record information, the recording code string of the test write data includes an input switch 12 that operates according to the test write command signal. Is output to the shaper 13. Thus, the AP that controls the laser driver 7 that drives the laser 8 so as to compare the recording code sequence from the encoder 4 with the reproduction code sequence from the discriminator 15 and cancel the difference between the reproduction code sequence from the recording code sequence.
A control signal for controlling C6 is output. As a result of such control, the difference between the reproduced code string from the recorded code string is reduced to some extent and becomes within an allowable range, and a test write end signal is output to end the test write. After the test write end signal is output, the input switch 12 switches to the waveform equalizer 11.
Is switched to be output to the shaper 13, and a normal recording / reproducing operation is started. Even after the normal recording operation is started, the comparison discriminator 16 confirms that the difference between the reproduced code string from the recorded code string is within an allowable range. If the difference is not allowable, the above-described trial writing operation is started. When the test writing end signal is output, the normal recording operation is continued again. When the difference between the recorded code sequence and the reproduced code sequence is confirmed by the comparison discriminator 16, the operation of the input switch 12 so that the output of the reproducing amplifier 10 outputs the signal can be detected more accurately. In the above operation, a similar operation can be realized without using the input switch 12. However, it is better to use a signal that does not pass through the waveform equalizer 11 in order to accurately detect a difference between a reproduced code string and a recorded code string in the comparison discriminator 16.
Next, an operation example of the apparatus of the present invention will be described with reference to FIG. The apparatus is operated by turning on the power or the like of the apparatus (2021). First, it is determined whether a recording medium has been inserted into the apparatus (2022). When the recording medium is set in the apparatus (2024), a test writing operation is performed to check the compatibility between the inserted recording medium and the apparatus (2024).
25, 2023). Test writing is an apparatus that controls recording power and recording pulses so as to minimize fluctuations in recording marks caused by fluctuations in recording sensitivity to the recording medium due to fluctuations in the thickness of the recording medium and fluctuations in the environmental temperature. Of the recording signal and the reproduction signal, the difference between the recording signal and the reproduction signal is suppressed to a range in which the apparatus operates normally, and a test writing end signal is output (2028). Operation (recording / reproduction of information) is started (2029). Further, the recording signal and the reproduction signal are compared and discriminated (2026). If the difference between the recording signal and the reproduction signal is large, the laser power is controlled (2027).
Then, test writing is performed again until normal operation is performed. Also,
At the time of replacing the recording medium (2024), the above-described trial writing is also performed. Further, even during normal operation of the apparatus, it is possible to always record a highly accurate recording mark by comparing the recording signal with the reproduction signal.
FIG. 3 illustrates the relationship between an embodiment of a recording method for recording on a recording medium according to the present invention and recorded recording marks. FIG. 3A shows a recording pulse for controlling the laser power. The output from the encoder 4 described with reference to FIG. The recording code sequence 0 corresponds to a recording mark recorded on the medium, and the recording waveform generator 5 generates a recording pulse sequence 21 in the pulse portion of the recording code sequence 20.
For example, the recording pulse train 21 differs from the first pulse in length of the second and subsequent pulses as shown in FIG. 3 and the pulse length of the second and subsequent lus trains is the minimum change length of the recording mark (for forming marks of a plurality of lengths). At least one pulse corresponds to the minimum change in the length of the light pulse. Further, it is composed of a recording pulse train in which the influence of heat of another pulse near the final falling position of the pulse of the recording mark can be almost ignored, or a recording pulse train in which a certain amount of heat flows.
A recording auxiliary pulse 22a is generated in a gap portion (pause period portion other than the pulse portion) of the recording code string 20. The recording auxiliary pulse 22a is provided with a gap in which the laser power is reduced for a certain period from the vicinity of the falling position of the recording code train 20 so that heat from the last falling position of the recording pulse train causes the leading rise of the next recording pulse train. Do not affect the temperature of the location.
FIG. 3B shows a change in laser power according to a recording code sequence when the laser 1 is driven using the recording pulse 21 and the recording auxiliary pulse 22a, with the horizontal axis representing time and the vertical axis representing laser power. did. The minimum level of the laser power is the reproduction power Pr at the time of reproduction. The highest level of the laser power is the recording power Pw of the recording pulse train 21. The intermediate level is the recording power Pas of the recording auxiliary pulse 22a.
It is. As shown in FIG. 3C, the length and width of the recording mark 23 on the recording medium are controlled with high precision using such a laser power waveform. Further, since the temperature on the recording medium is kept constant, the width of the recording mark 23 is controlled within a certain range, so that the amplitude of the reproduction signal 24 becomes constant. A reproduced code string 25 is generated by detecting the center of the reproduced signal 24 or making a determination using a certain threshold value .
As an example of the operation of the comparison discriminator 16, FIG.
The recording code string 20 shown in FIG. 3A and the reproduction code string 25 shown in FIG.
Then, the length of the pulse portion and the interval such as the rising position or the falling position of the pulse are compared and evaluated. For example, when the recording power is too large, the pulse length of the reproduction code string 25 becomes longer than the pulse length of the recording code string 20. Also,
When the recording power is small, the pulse length of the reproduction code string 25 is shorter than the pulse length of the recording code string 20.
As a detection method, "Digital signal recording / reproducing apparatus" filed by two inventors has been disclosed in Japanese Unexamined Patent Publication No. Hei.
1028. Here, we propose a new method that does not increase the size of the detection circuit. As a recording pattern used as a test pattern, for example, FIG.
The shortest recording mark and the longest recording mark determined by the recording modulation code shown in FIG. When the 1-7 modulation is used as the modulation method, the bit period is set to T and 1.3.
The length corresponding to 3T and 5.33T is good. Bit density of 0.56 micron / bit, laser wavelength of 780n
Assuming that m and the NA of the lens are 0.55, the length of the shortest mark is 0.75 μm, and the reproduced waveform from this point is only a fundamental wave without a harmonic component in view of the resolution of the optical system. Generally, the reproduction waveform is affected by both the length and the width of the mark because the shortest mark is smaller than the diameter of the reproduction spot.
On the other hand, the signal amplitude of the reproduction waveform of the longest mark is determined only by the influence of the width, and the rising and falling intervals of the signal correspond to the mark length. When the recording waveform as in the present invention shown in FIG. 3 is used, the widths of the longest recording mark and the shortest recording mark can be made substantially equal, so that the difference between the reproduction waveforms of the shortest mark and the longest mark can be regarded as a difference in length.
A so-called mark length recording in which information is given to both edges of the mark is performed, and this is converted into a data pulse.
If a direct slicing method is adopted as a quantification method, it is necessary to accurately determine the slice level. It has been found that this level has the same mark width, and when the shortest mark length is longer than half the light spot diameter, it is sufficient to set the level to half the amplitude level of the longest mark length. In other words, if the mark length is longer than half of the light spot diameter, and there is a light spot at the mark edge, the reproduction signal from this mark edge is not affected by the edge of the adjacent mark, so the amplitude determined by the longest mark length The intersection with the reproduced waveform when slicing at the half value of the mark corresponds to the edge of the mark.
For detecting the mark length from the test-written signal waveform for the above reason, it is necessary to first set a slice reference level. For this purpose, a reference level is obtained from a reproduced waveform of a repeated pattern of the longest mark.
As this method, in order to obtain the half value of the amplitude of the longest mark, signals indicating the upper envelope and the lower envelope of the reproduction signal from the mark are created from an envelope detection circuit, and the average value thereof is obtained to obtain a reference level and a method. Is known (Japanese Unexamined Patent Publication No.
Another method for setting the slice level will be described below. In the longest mark repetition pattern, the mark length and the mark gap length are recorded so that they are equal. However, even if the recording conditions deviate and the balance between the mark length and the mark gap length slightly shifts, the longest mark repetition pattern is used. Then, the average value is almost equal to the value obtained by the above method. A circuit as shown in FIG. 6 is used as a method for obtaining this. A binarization circuit 601 binarizes the reproduced waveform at a variable slice level to form a pulse. The charge / discharge circuit 602 activates the integration circuit at the rising edge of the pulse, performs charging, and discharges at the falling edge. The sample and hold comparator 603 samples and holds the value of the integrator at the timing of the rising edge of the next pulse, and the slice control unit 604 instructs the binarization circuit 601 to change the slice level so that the sample and hold value becomes zero. The field level is applied, and when the slide level is set, the slice level is converted from analog to digital by the A / D converter 605 and stored in the memory circuit 606 and stored. This operation is similarly obtained for the shortest mark and the longest mark, and when the respective values are V1 and V2, the recording condition is changed so that the difference becomes zero.
(Embodiment 2) FIG. 4 shows another embodiment of a recording system for recording on a recording medium according to the present invention. As shown in FIG. 1, the recording code string 20 is converted by the recording waveform generator 5
A recording pulse train 21 is generated in the pulse portion of the recording code train 20. The recording pulse train 21 differs from the first pulse in the length of the second and subsequent pulses, and the pulse length of the second and subsequent pulse trains corresponds to at least one of the minimum change lengths of the recording mark, and It is composed of a recording pulse train in which the influence of heat from other pulse trains in the vicinity of the final falling position of the pulse is almost negligible, or a recording pulse train in which a certain amount of heat flows.
In FIG. 4A, a recording auxiliary pulse 22b is generated in a gap portion of the recording code string 20 (corresponding to an interval between recording marks in a pause period other than a pulse portion). The recording auxiliary pulse 22b is provided with a portion for lowering the laser power for a predetermined period before the rising position of the recording code sequence 20 and for a predetermined period from the falling position of the recording code sequence 20, so that heat from the last falling position of the recording pulse sequence is generated next. Is hardly changed at the head rising position of the recording pulse train.
FIG. 4B shows the change in laser power according to the recording code sequence when the laser 1 is driven using the recording pulse train 21 and the recording auxiliary pulse 22b, with the horizontal axis representing time and the vertical axis representing laser power. did. The minimum level of the laser power is the reproduction power Pr at the time of reproduction, the high level at the time of recording is the recording power Pw of the recording pulse train 21, and the low level at the time of recording is the recording power Pas of the recording auxiliary pulse 22a. The length and width of the recording mark 23 on the recording medium are controlled with high accuracy by using a recording waveform such as a graph. Also, since the temperature on the recording medium is kept constant, the recording mark 2
Since the change in width of 3 is controlled within a certain range,
The amplitude of the recording portion of the reproduced signal 24 becomes substantially constant. By making a determination at the center or at a certain level of the reproduction signal 24, a reproduction code string 25 is generated.
Consider the temperature distribution on the disk surface controlled by the above recording waveform. The maximum temperature reached by the recording pulse is represented by Tmax, and the temperature rise due to the reproducing laser power is represented by KPr using a specific coefficient K.
The ambient temperature of the apparatus is defined as Tr, and the temperature rise due to the recording laser power is represented as K '(Pw-Pas) using the specific coefficient K'. Further, if a function with respect to time t representing the rate of temperature decrease after the end of the recording pulse irradiation is f (t), and a function representing the rate at which the temperature rises after irradiation of the auxiliary pulse is g (t), With the origin of the time t as the end point of the recording pulse, the temperature (t) can be expressed as follows.
(Tmax−Tr−KPr) f (t) + Tr + KPr + K (Pas−Pr) g (t) = T (t) (1) Assuming that the detection window width in the 1-7 modulation is Tw, The shortest mark length and the shortest gap are both 2 Tw. The most severe condition for considering the above-mentioned heat balance is when the mark gap is the shortest. Therefore, the shortest time from the end of the mark gap to the start of the next mark portion is when t is 2 Tw, and the longest time is 8 Tw. In order that the influence of heat when the previous mark is recorded has no influence regardless of the pattern of the next mark, T (t) should be 8 from 2 Tw of t.
It is desired to take a constant value C during Tw. In addition, in order for all the marks to have the same width, the constant value C must be set as the temperature rise K ′ (P
(w-Pas) is the condition that the highest temperature reached as a result of addition is equal to the highest temperature Tmax reached in the previous mark. Further, as a constant value C,
It is necessary that the temperature ultimately reached as a result of the heat balance between at least t 2Tw and 8Tw in order for the preceding mark to have no effect on the subsequent mark. This temperature is
F (t) → 0 g (t) → 1 (Formula 2) It is obtained as the limit of Formula 2. After all C
C = Tmax−K ′ (Pw−Pas) = Tr + KPr + K (Pas−Pr) (Equation 3)
## EQU4 ## If the error between T (t) and C is E (t), E (2Tw) = K '(Pw-Pas) f (2Tw)-(1-f (2Tw) -g (2Tw)) K (Pas-Pr) (Equation 4) Since it is easier to understand the change amount of the heat source as an element that determines the heat flow, the power change of the recording pulse is expressed by P
w ', the power change of the recording auxiliary pulse is Pas'
Pw ′ = Pw−Pas Pas ′ = Pas−Pr (Expression 5) Then Equation 4 becomes
E (2Tw) = K′Pw′f (2Tw) − (1−f (2Tw) −g (2Tw)) KPas ′ (Equation 6) According to this equation, the first term on the right side is the influence of the recording pulse of the previous mark, and the second term is the influence of the recording auxiliary pulse. To cut off the recording auxiliary pulse means to control the coefficient of the second term. If the recording auxiliary pulse is not cut off, this term becomes zero constantly, and in principle, the influence of the recording pulse cannot be eliminated. . Number 6
As can be seen from the above, in order to eliminate the influence of the recording pulse of the previous mark, E (2Tw) must be within a temperature error where the shift of the mark edge has almost no effect.
In order to satisfy this, Pw ′, Pas ′, f (2T
The combination of w) and g (2Tw) must be considered.
On the other hand, the combination of Pw ′ and Pas ′ is determined from another viewpoint. From Equation 3 showing the steady-state relationship between the recording auxiliary pulse, recording pulse, and ambient temperature
Tmax = Tr + KPr + KPas '+ K'Pw' (Formula 7) Formula 7 is obtained. Here, the mark width is determined when the spot shape, the linear velocity, and the thermal conductivity of the medium are determined, and the mark length is determined when the recording pulse waveform is determined. Therefore, the mark width and the length are controlled to be constant. To do so, Tmax must be kept constant. That is, the right side of Equation 7 does not become constant. Then, when the environmental temperature and the reproduction power are determined, the sum of Pw 'and Pas' must be constant. Here, the factors that determine K are the spot shape, the linear velocity, and the heat conduction characteristics of the medium, and K ′ is these and the recording pulse waveform. In order to reduce the error from Equation 6, consider that the function of f (t) and g (t) is a function representing the rate of decrease and increase in temperature, so that only a value between 1 and 0 is taken. Then, it is more convenient for KPas 'and K'Pw' to be substantially equal, because the allowable range for f (t) and g (t) becomes wider. f (t) and g (t) are determined by the heat conduction characteristics of the medium, and as described above, f (t) can be determined by the relationship between the linear velocity and the heat conduction velocity. G (t) is determined by the heat capacity and the linear velocity of the film. Now, suppose that the rate of temperature decrease and increase is an exponential function of time t, and a specific number is tau.
1, tau2, and the auxiliary light cutoff time is t0.
F (t) = exp (−t / tau1) (8)
Equation 9] g (t) = 1-exp (- (t-t0) / tua2), t ≧ t0 g (t) = 0, t <t0 ... ( number 9) recording waveform as described later recording clock It is very convenient for the realization of the circuit to be synchronized with. Therefore, the time t is expressed in units of the detection window width Tw of 1-7 modulation. Assuming that KPas 'is 80 degrees, K'Pw' is 100 degrees, the cutoff time is Tw, and the temperature error of T (2Tw) is within ± 10 degrees, the combination of tau1 and tau2 satisfying this condition is as shown in FIG. Become. This value is obtained by using a magneto-optical recording film, a medium described in JP-A-61-90348, and a linear velocity of 9.4
m / s, Tw is 40 ns and the edge shift is 1 of Tw
This is a condition within 0%. The square area represents an area where the steady state is reached immediately because the rate of increase in attenuation is fast. The area where the heat is balanced by the cutoff is the shaded area, and the above-mentioned Pw ′, Pas ′, f (2Tw), g
(2Tw) is an area determined by four combinations.
It is desirable to select a rectangular area as the area in order to reduce the temperature error even if each element of the four combinations fluctuates. Above all, if tau1 is set to 0.4 or less, the influence of K'Pw 'is greatly suppressed, so that the allowable range for the cutoff time and tau2 is expanded. When the mark length recording is used as the recording method and the MCAV recording is performed, the absolute time of Tw changes depending on the radial position. However, if the cutoff time and the time constant are standardized by Tw, all the results up to now are satisfied.
(Embodiment 3) Next, another embodiment of the recording pulse will be described. In the embodiments described above, in order to record the shortest mark of 1-7 modulation in FIGS.
A combination of a leading pulse of w and one subsequent recording clock pulse is used. Here, generally, a recording clock having a Tw period is oscillated, so that it is convenient to use the recording clock for convenience of the circuit. Actually the transfer rate is 4MB /
When it is close to s, it is difficult to generate a clock having a double period. However, in order to record the shortest mark by using a combination of the power levels corresponding to one recording pulse and to increase the mark length by Tw for each subsequent recording clock pulse, it is necessary to use a recording medium. Has limited thermal properties. In the case of the above-mentioned time constant, this is a case of a considerably large value.
As a waveform that can be applied to a medium having various thermal characteristics, a shortest mark is recorded by a pulse having a recording power variation W1 of length a as shown in FIG. A desired width is obtained by a combination of the recording auxiliary pulse of the level Pas and the recording pulse, and 1.
The shortest mark having a length of 33T can be recorded. Then T
When recording the mark that follows every w, the recording power change amount is recorded as W2 using the above-described recording clock.
In order to keep the mark width constant irrespective of the mark length, the maximum attained temperature for each recording clock is made constant. In FIG. 8, the temperature at each point from timing t2 to t6 will be obtained. Assuming that h (t) is a function representing the increase in heat due to the pulse irradiation and 1 (t) is a function representing the decrease in heat due to the stop of the pulse, the increase in the heat due to the recording pulse has the relationship shown in FIG. 9 at each timing. P, for simplicity
When the condition of W2 is determined so that the temperatures at t2 and t3 are equalized by substituting Q and R, the relationship shown in FIG. 9 is obtained.
W2 = R (1-P) W1 / Q (Equation 10) In this way, the temperatures from t4 to t6 are almost equal.
The pulse width a is created from a pulse width of 2 Tw using a delay line or the like. By using the power levels of the two recording pulses, it is possible to equalize the maximum attained temperature for each pulse. However, the drawback of this method is that the recording pulse widths a and d even if one medium is determined, as is apparent from Equation (10).
Since the Q and R change with the fluctuation of the recording apparatus and the fluctuation of the rise characteristic of the laser drive circuit, the temperature at each timing is different and cannot be corrected. However, as shown in FIG. 9, the recording clock is used as it is, and the power for recording the shortest mark and the power of the succeeding pulse are changed to W1 and W2, respectively. A power W1 for forming the shortest mark is determined. Here, the temperature reached from timing t1 to t5 is obtained, and t2 and t3 are obtained.
When W2 is obtained from the condition for equalizing the temperature at
W2 = (1−PP) W1 (Equation 11) Equation 11 is obtained. In this case, if the characteristics of the medium do not change, fluctuations in the recording pulse, such as fluctuations in the recording pulse width and fluctuations in the rise characteristics of the laser drive circuit, change the temperature change at each timing at a uniform rate. ,
This effect can be eliminated by the test writing of the present invention. That is, since the temperature change is constant regardless of the mark length, it can be corrected by changing the recording auxiliary pulse. In order to synchronize with the recording clock in FIG. 8, a may be set to Tw. However, at this time, if the width and the length are combined, it becomes difficult to control the width.
The relationship between the test writing operation and various fluctuation factors is expressed by the following equation (7).
This will be described with reference to FIG. When the environmental temperature change changes from Tr1 to Tr2, the change Pas' of the auxiliary light is changed to change the Tm.
ax is kept constant. With respect to variations in the thickness of the recording medium and variations in the recording sensitivity, the recording temperature varies. It will be controlled to compensate for the amount. When the recording power changes, Pr and Pas'Pw 'change. This also changes the change Pas' of the auxiliary light to change Tmax.
Can be kept constant. KPas 'is also K'Pw'
Must be of the same order as Variations in recording characteristics due to the recording / reproducing apparatus are variations in K and K '. Tmax can be kept constant by changing the variation Pas' of the auxiliary light.
(Embodiment 4) Still another embodiment will be described. FIG. 10 is a schematic diagram showing the shape of the recording pulse used. The recording power was 6.5 mW for the first pulse and the second pulse of the recording area at the innermost position of the disk where the rotation of the disk medium was 3000 rpm, and 6 mW for the third and subsequent pulses. The preheating power is 2.3 mW, and the pulse width and gap interval are all 20 ns. This interval is set from the recording clock. Also, although the case where the head pulse is increased in the disk medium of the present embodiment is shown, this may be reduced depending on the structure of the recording medium. Recording was performed on the disk using the light pulse of FIG. Then, a portion having a low power between the recording pulses is provided immediately after the recording pulse,
The period was set to 40 ns. These values are determined by the medium structure of the magneto-optical disk, and the compatibility between the mediums can be secured by determining the parameters by performing a trial recording.
FIG. 12 is a schematic diagram of a reproduced signal waveform and a recording magnetic domain when the shortest 11.33T mark is recorded after the longest 5.33T mark using the (1,7) RLL modulation method.
Shown in Here, the formed magnetic domain width is 0.7 μm, and the magnetic domain length is 0.75 μm at the shortest and 3.0 μm at the longest. From this figure, neither the shortest magnetic domain nor the longest magnetic domain is affected by each other, the magnetic domain width is constant without depending on the pattern length, and three shortest 1.33T are recorded after 5.33T. Even in this case, since all the 1.33T magnetic domains have the same length, it can be seen that the magnetic domains are not affected by heat from the previous magnetic domain.
FIG. 13 shows the difference between the pulse width of the recording signal and the width of the reproduction signal when recording various patterns based on the (1, 7) modulation. From this figure, the edge shift at that time was not more than 5% of the detection window width without depending on the formed magnetic domain length.
When recording / reproducing / erasing was repeated, no change was observed in the carrier level and the noise level even after repeating 5 × 10 7 times.
Similar effects were obtained by using any of the waveforms shown in FIGS. 11 and 14 other than FIG. 10 as the pulse shape. Here, the pulse and the gap interval were both set to 20 ns. The first pulse width is the pattern I
7.5 mW is appropriate for the pattern II, and 6.5 mW for the pattern II.
7 mW was optimal. However, these values are chosen according to the thermal structure of the medium used.
 PC which is easy to warm up as a disc structure
Substrate / SiNx (75 nm) / TbFeCoNb (25
nm) / SiNx (20 nm) / Al 97 Ti 3 (50 n
m), the power of the first pulse is as low as 5.5 mW, and conversely, the power of the second and subsequent disks is 5.5 mW.
By setting as high as 95 mW, the shift is ± 2 nm.
The following could be suppressed.
(Embodiment 5) Still another embodiment will be described. FIG. 15 is a schematic diagram showing the shape of the recording pulse used. The recording power was 6.7 mW at the innermost position with respect to the rotation of the disk medium at 3000 rpm, and the subsequent power was 6 mW. The preheating power is 2.3 mW, the leading pulse width is 55 ns, and the subsequent pulse width and gap interval are both 20 ns. Recording was performed on the disk using this pulse.
FIG. 16 is a schematic diagram of a reproduced signal waveform and recording magnetic domains when the shortest 1.33T is recorded after the longest 5.33T using the (1,7) RLL modulation method. here,
The formed magnetic domain width is 0.7 μm, and the minimum magnetic domain length is 0.75 μm.
m, at most 3.0 μm. From this figure, neither the shortest magnetic domain nor the longest magnetic domain is affected by each other, the magnetic domain width is constant without depending on the pattern length, and three shortest 1.33T are recorded after 5.33T. In any case, since the 1.33T magnetic domains have the same length,
It can be seen that heat is not affected by the previous magnetic domain.
FIG. 17 shows the difference between the pulse width of the recording signal and the width of the reproduction signal when various patterns based on the (1,7) modulation are recorded. From this figure, the edge shift at that time was not more than 5% of the detection window width without depending on the formed magnetic domain length.
When recording / reproducing / erasing was repeated, no change was observed in the carrier level and the noise level even after repeating 5 × 10 7 times.
The same effect can be obtained by using any waveform shown in FIG. 18 other than FIG. 15 as the pulse shape. In the case where the magneto-optical recording medium has a structure that is easy to warm up and easy to cool, it is necessary to make the pulse width longer than that of the succeeding pulse in order to provide both the properties of recording at the same time as preheating the first pulse. Here, it is desirable that the pulse width be an integral multiple of the recording clock or a fraction thereof.
FIG. 19 shows a specific configuration of a laser drive circuit for realizing test writing according to the present invention. FIG. 19 (a)
The powers Pw 1 , Pw 2 , Pas, and Pr of the recording waveforms shown in FIG.
On the other hand, in the drive circuit shown in FIG. 19B, the current sources, Iw1, Iw2, Ias, and Ir are respectively set so that the laser light has a predetermined power in consideration of the current-light conversion efficiency of the laser and the efficiency of the optical head. Set it. Since only Ias is controlled by trial writing, it is set to be variable.
Whether each current is supplied to the laser or not is controlled by each recording pulse by the current switch CS. As shown in FIG. 19C, this current switch circuit does not use a pnp type in order to improve the response by + driving, but has a special driving circuit configuration for switching by an npn type. That is, the current source I shown in FIG. 19D constantly supplies the maximum current, and only the current values of the current sources Ir, Iw 1 , Iw 2 , and Ias on the current switch side are supplied to the laser by the current switch CS. It is configured to reduce the flowing current. Therefore, the pulses Pr, Pw 1 , Pw 2 , P
“as” must have a polarity inverted from that of the optical recording waveform. In the test writing of the present invention, the above-described recording pattern is recorded on one track by changing the magnitude of the recording auxiliary pulse for each sector indicating a data break. The number of sectors is 5.
In the MCAV recording system in which the diameter is 25 inches and the linear density is about 0.56 microns / bit, there are 32 in the inner circumference.
For example, in one trial writing, the amount of change of the auxiliary light is changed in five steps. Initially, it is changed in five steps. This is done when the disc is first loaded and when the disc is changed. Next, it is determined which of the greatly changed amounts is present, and the interval is further divided and changed into five stages.
FIG. 20 shows the procedure of trial writing. The most severe condition for the frequency of trial writing is from when the apparatus is turned on to when the temperature reaches a temperature at which the heat can be balanced.
Although it depends on the heat generation conditions of the circuit, the temperature rises by about 10 ° C. in 5 minutes at the maximum. If initially set, it can be controlled sufficiently even every 5 minutes.
In FIG. 20, when the optical disk is replaced, when the power of the apparatus is turned on, or at an appropriate time during the operation of the apparatus, the test writing operation is performed (2001).
Next, an area on the medium where test writing is to be performed is selected (200).
1). In the test writing area, for example, a dedicated area (test writing track area) is set on the outer, inner, or middle track of the optical disc. One track in the test area is erased in preparation for the case where some recording such as trial writing has already been made in the test area (2004). Next, a test writing test pattern is recorded on this track. As the test pattern, for example, a pattern in which the patterns shown in FIGS. 5 and 25 are recorded with the recording pulse trains shown in FIGS. 3, 4, 8, 10, 11, 14, 15, or 18 is used. . In this embodiment, recording for one round of a track is performed by changing the power Pas of the recording auxiliary pulse for each sector using the pattern of FIG. 5 (2005 to 2009).
Next, the recorded test pattern is reproduced (2010, 2011) and evaluated. The evaluation was performed by taking the difference ΔV between the center level V1 of the reproduced waveform of the densest pattern of the test pattern and the center level V2 of the reproduced waveform of the sparsest pattern (2012). The value of ΔV is taken in for each sector (2013 to 2015). Thereafter, the recorded test pattern is erased (2016). Then, the value of Pas in the sector having the smallest ΔV is determined as the optimum power of the recording auxiliary pulse (2017). In this embodiment, this operation is performed on each of the outer circumference, inner circumference, and middle circumference of the optical disk (2018).
After the end, a normal data recording operation is started (2019).
(Embodiment 6) FIG. 21 is a schematic diagram showing a sectional structure of a disk used in this embodiment. For the disk, a recording medium was formed by a sputtering method on a plastic or glass substrate having an uneven guide groove. The medium is a SiNx film having a thickness of 80 nm and a T
bFeCoNb film is 25 nm, SiNx film is 20 nm,
Then, the Al 96 Ti 4 film was continuously laminated without breaking the vacuum in the middle of 50 nm. Here, the reason why the continuous lamination is performed is to suppress formation of an impurity layer such as oxygen at a layer interface. Further, this laminated structure is only one example, and the effect of the present invention is not impaired by the laminated structure.
Conversely, according to the present invention, minute magnetic domains can be stably formed, and thus ultra-high-density optical recording can be realized. Also, although a magneto-optical disk having a four-layer structure is shown here, the effect of the present invention is not related to the number of layer structures.
Recording was performed on this disk using the waveform having the pulse shape shown in FIG. The pulse width of the recording waveform is periodic with the write clock of the disk device. This is advantageous not only in facilitating the creation of a clock signal and in reducing the cost of the device, but also has a feature that the accuracy of the clock is high. The recording waveform has four power levels. The first level is a read (reproduction) level, and Pr = 1.5 mW. The second level is an assist (auxiliary) level, Pas = 2.7 mW, and the third level is a first recording level, Pw1 = 5.1 mW. The fourth level is the second recording level, Pw2 = 5.9 mW
It is. Recording was performed using a (1,7) RLL modulation method as a signal modulation method. A pulse width of 1.33 T, which is the shortest in this modulation method, was formed with a pulse width of 60 ns and a laser power of Pw1. After that, Pa for 20 ns
After passing through the s level, a 2T bit was formed with 20 ns of Pw2, and a pulse of 2.66T to 5.33T was formed by this repetition .
The magnetic domains recorded by the above method were reproduced (using the front and rear edge independent reproduction method). The window margin was 30% and the shift was ± 2 ns or less. here,
The pattern used for the measurement is random.
In this embodiment, SiNx is used as a material. However, if the dielectric material is an inorganic compound which does not absorb optically, at least one compound selected from aluminum nitride and silicon oxide in addition to silicon nitride is used. Can be used.
Further, in this embodiment, Al 96 Ti 4 was used as a metal layer for controlling light reflection and heat flow.
At least one element selected from Au, Ag, Cu, Al, Pd, and Pt is used. In order to further control the thermal conductivity, N is added to the elements other than the above-mentioned parent element.
A film in which at least one element selected from b, Ti, Ta, and Cr is added in an amount of 0.5 at% or more and 30 at% or less can also be used.
(Embodiment 7) Next, another embodiment of the present invention will be described with reference to the drawings.
First, the process of shifting the edge position and the principle of suppression will be described.
FIG. 23 schematically shows how the edge position shifts due to thermal interference.
In FIG. 23, the horizontal direction indicates the passage of time or the spatial coordinates on the recording medium where the light spot moves. The recording signal 201 modulates the recording information to show the temporal transition of the intensity of the light spot irradiated on the recording medium, and the recording mark 23 shows the shape of the recording mark formed on the recording medium by the recording signal 201. . Also, the reproduction signal 24
Is obtained by scanning the recording mark 23 with a light spot having a light intensity of a readout level, receiving reflected light from the recording medium at that time by a photodetector, and performing photoelectric conversion. The binarized reproduction signal 25 is a reproduction signal 24 reflecting the recording mark shape.
Is binarized depending on whether the signal level is above or below a predetermined signal level.
FIG. 23 shows the first rising edge of the recording signal 201, the leftmost front edge position of the recording mark 23, and the first rising edge position of the binarized reproduction signal 25 together. . L [i], B
[I] represents the length of each pulse interval (from the rising edge to the falling edge) and the length of the gap interval (from the falling edge to the rising edge) of the recording signal 201, and i represents the first recording pulse (binary (Reproduced pulse), the serial number (initially 0).
As an information recording mechanism, in an optical information recording method in which a recording mark is formed by heat given by a light spot, the heat given by the light spot diffuses through a recording medium in a cooling process. As a result, the temperature around the light spot increases. Therefore, when the size of the recording mark and the interval between the recording marks are reduced in order to perform high-density recording, the individual pulse shapes of the recording signal not only determine the corresponding recording mark shapes but also the surrounding recording marks. It also affects the shape. Conversely, the shape of each recording mark is not determined only by the corresponding recording pulse shape, but is affected by the temporally adjacent recording pulse shapes.
As described above, the recording mark is affected by the recording pulses that are temporally adjacent to each other. As a result, a shift occurs between the pulse interval of the recording signal 201 and the edge position of the recording mark 23. As a result, a relative shift e between each edge position of the recording signal and each edge position of the binarized reproduction signal 25 is obtained.
[I] and f [i] are generated. Here, e [i] is the amount of deviation between the falling edge of the recording signal 201 and the falling edge of the binarized reproduction signal 25, and f [i] is the difference between the rising edge of the recording signal 201 and the binarized reproduction signal 25. It shows the amount of deviation of the rising edge. I is a serial number (0 at the beginning) from the rising edge and the falling edge of the first recording pulse (binary reproduction pulse), and f
 is set to zero.
At this time, the edge shift amounts e [i], f
[I] Although it depends on the thermal conductivity characteristics and recording density of the recording medium, for example, TbFe
For a recording medium having a structure composed of a Co magnetic film, a dielectric film, a protective film, and a reflective film, a recording linear velocity of about 10 to 20 m / s,
When the shortest recording mark length is about half the light spot diameter as the recording density, it can be expressed by the following equation using the pulse length L [i] of the recording signal and the gap length B [i].
E (i) = Se (B [i-1], L [i] (Equation 12)
F [i] = Sf (L [i-1], B [i-1] (Expression 13) Here, Se () and Sf () represent functions, that is, e [i ] Is determined by the immediately preceding pulse interval L [i] and the preceding gap interval B [i-1], and f [i]
Is determined by the immediately preceding gap interval B [i-1] and the preceding pulse interval L [i-1].
Note that for e [i], the pulse interval L
Regarding the effect before [i-1] and after the gap interval B [i], and the effect after f [i], the influence before the gap interval B [i-2] and after the pulse interval L [i] is small and need not be considered. No problem.
Next, a description will be given of how the influence of the edge shift is suppressed by adjusting each edge position of the recording signal using the information of the above-described edge shift amount, with reference to FIG. FIG.
The horizontal direction indicates the passage of time or spatial coordinates on the recording medium where the light spot moves, and the recording signal 30
Reference numeral 1 denotes an electric signal obtained by modulating the recording information and an adjusted signal 302.
Represents the temporal transition of the electric signal level in which the rising and falling edge positions of the recording signal 301 are shifted according to the recording pattern, and this signal modulates the intensity of the light spot irradiated on the recording medium.
The recording mark 23 is the signal 302 after the adjustment.
Indicates the shape of the recording mark formed on the recording medium. The reproduction signal 24 is obtained by operating the recording mark 23 with a light spot having a light intensity of a reading level, receiving the reflected light from the recording medium at that time with a photodetector, and performing photoelectric conversion. The binarized reproduction signal 25 represents an electric signal obtained as a result of binarizing the electric signal reflecting the recording mark shape depending on whether the signal level is above or below a predetermined signal level.
Note that the first rising edge of the recording signal 301, the leftmost front edge position of the recording mark 23, and the first rising edge position of the binarized reproduction signal 25 are shown together. L [i] and B [i] represent the length of each pulse interval (from the rising edge to the falling edge) of the recording signal 301 and the length of the gap interval (from the falling edge to the rising edge),
E [i] and F [i] are the recording signal 301 relating to each falling edge and rising edge of the adjusted signal 302.
Represents the amount of shift from each edge position. further,
i represents a serial number (0 at the beginning) from the first recording pulse (binary reproduction pulse).
The principle of adjusting the recording pulse edge position is as follows. Always shifted to the edge position of the recording mark with respect to the edge position of the recording signal is generated. But,
Conversely, by shifting each edge position of the original recording signal 301 in advance to obtain the adjusted recording signal 302, each edge position of the binarized reproduction signal 25 deviates from the edge position of the recording signal 302. The edge position of the recording signal 301 coincides with the edge position. The amount of deviation of the edge position of the recording mark 23 from the edge position of the recording signal 301 can be determined by referring to the recording pattern and using the above relational expression. Therefore, it is possible to obtain the amount by which the edge position is shifted by using the inverse function of this relational expression and the amount of shift of the binarized reproduction signal with respect to the recording signal so that the sign is reversed and the magnitude is the same. That is,
Γ = Sf (α, β) + β (Expression 14)
Β = Cf (α, γ) (Equation 15)
Γ = Se (α, β) + β (Expression 16)
[Mathematical formula-see original document] β = Ce (α, γ) (Equation 17)
F [i] = B [i-1] + E [i-1] -Cf (L [i-1] + F [i-1] -E [i-1], B [i-1] + E [i-1] (Equation 18)
[Equation 19] E [i] = L [i] + F [i] -Ce (B [i-1] + E [i-1] -F [i], L [i] + F [i]) (number 19) E [i] and F [i] can be obtained as follows.
In Equations 18 and 19, the edge position shift amounts are included in the functions Ce () and Cf (). However, this shift amount is E
, F , E , F , E
If it is sequentially obtained in the order of ,..., For example, F [i]
Is obtained by using E [i-1] and F
[I-1] is calculated at the previous time, and when calculating E [i], F [i] and E [i-1]
Is calculated at the time before that, so that F [i] e [i] can be calculated from Expressions 18 and 19, respectively.
Next, the principle of a method for detecting a change in the light beam intensity during recording and a change in the temperature of the recording medium and coping with the change will be described.
Even when the light beam intensity at the time of recording changes or the temperature of the recording medium changes, a deviation occurs between each edge position of the recording signal and the edge position of the recording mark. For example, if the light beam intensity during recording has decreased,
The recording mark is generally smaller, and the position of the front edge of the recording mark is shifted to the rear side, and the position of the rear edge of the recording mark is shifted to the front side.
The amount by which each edge position of the recording mark is shifted differs for each recording mark to be formed. Therefore, in order to reduce the deviation of the edge position of the recording mark that occurs when the light beam intensity at the time of recording is changed by changing the edge adjustment amount for each recording pattern as described above,
It is necessary to change the edge adjustment function for each light beam intensity at the time of recording, and the circuit system becomes large-scale. Therefore, if it is detected that the light beam intensity at the time of recording has changed in order to prevent edge displacement with a simpler system,
An adjustment is made so that the light beam intensity at the time of recording returns to the original value.
On the other hand, even when the temperature of the recording medium is lowered, the recording mark becomes smaller in general. In this case, the position of the front edge of the recording mark is on the rear side, and the position of the rear edge of the recording mark is on the front side. Shift. The temperature cannot be directly controlled to a constant value unless a temperature control mechanism is provided in the apparatus. Here, the edge position fluctuation characteristics of the recording mark due to the temperature fluctuation show a tendency that is considerably close to the case where the light beam intensity at the time of recording changes in a range where the fluctuation amount from the assumed temperature is small. Therefore, this range is dealt with by changing the light beam intensity at the time of recording, and when the value greatly fluctuates with respect to the set value, the function for adjusting the edge position during recording is changed.
To detect the above change, a predetermined recording signal is recorded in a dedicated area on the recording medium at predetermined time intervals. Immediately after that, the signal is reproduced to detect the shift amount of each edge position, and the change in the light beam intensity at the time of recording and the temperature change of the recording medium are separately detected from the result.
FIG. 25 shows an example of a recording signal pattern used at that time. In this recording signal 401, a plurality of edge intervals in a range of recording mark lengths that can be taken at the time of normal information recording are arranged so that the pulse width from the shortest or the longest one becomes equal to the pulse interval immediately after it. Use multiple repetitions. The reason for using the repetition is to reduce the influence of noise components included in the detection result and improve the accuracy of the measurement result by the averaging process. Here, 2-7 RLLC (RunLength Li
(Committed Code), and shows an example in which a recording signal is configured as being modulated by Pw , Pw 
,... Represent the edge interval of the recording signal pulse as Gw
, Gw ,... Represent the edge intervals of the recording signal gap. Note that T in the other edge interval notation of the recording signal 401 is a time length per information bit.
A reproduction signal 402 represents a binarized reproduction signal waveform when a recording mark written by the recording signal is read. .., Pr , Pr ,... Indicate the edge intervals of the reproduced signal pulse as Gr , Gr.
,... Represents the edge interval of the reproduction signal gap.
FIG. 26 shows a recording signal 401 and a reproduction signal 4.
Means for separately detecting a change in the light beam intensity during recording and a change in the temperature of the recording medium from the relationship of 02. The horizontal axis represents the pulse interval Pw [i] of the recording signal 401, and the vertical axis represents the value obtained by subtracting the immediately following gap interval Gr [i] from the pulse interval Pri of the reproduction signal 402. It is plotted. In this measurement result, the whole measurement point
If it is above the level, it means that the light beam intensity during recording has changed in a direction larger than the set value or the temperature of the recording medium has changed in a direction higher than the assumed value. Conversely, if the entire measurement point is below the 0 level, the light beam intensity during recording has changed in a direction larger than the set value, or the temperature of the recording medium has changed in a direction higher than the assumed value. Is represented.
When the light beam intensity at the time of recording changes, a measurement point comes on one curve in a fixed curve group. Therefore, when the light beam intensity at the time of recording changes, the curve group drawn by the measurement point is checked in advance, and the information is stored in the apparatus, so that all of the curves are plotted on one of the curves. Whether or not a change in the light beam intensity at the time of recording can be determined can be determined based on whether or not the measurement point is set. If all the measurement points are not on one curve, it is detected whether the curve is shifted to the lower right or lower to the left, and the temperature of the recording medium rises from the result. Is determined, and the edge position adjustment table for recording is changed accordingly.
Next, an embodiment including the above-described principle of adjusting the edge position and determining the recording condition will be described.
FIG. 27 is a block diagram showing the structure of the embodiment.
In FIG. 27, the optical disk 1 is rotated at a constant angular velocity by a spindle motor 109, and a laser beam for recording and reproduction is focused on the recording film surface of the disk 1 by an optical pickup 2 by a focusing lens. The optical pickup 2 can move in the disk radial direction corresponding to the information recording position.
After the signal detected by the detector in the optical pickup 2 is amplified to a desired level by the amplifier 10, the waveform is equalized by the equalizing circuit 11, and the resolution of the reproduced signal is secured. You. Thereafter, this signal is converted by a binarizing circuit 13 into a reproduced binary signal 2 which is a digital signal.
Converted to 77, PLL (Phase Locked Loop)
The signal is separated into a data signal and a clock signal by the circuit 14 and becomes reproduced data by the demodulation circuit 17.
The above is the data reproduction signal processing system of the optical disk system adopting the normal mark length recording method. The reproduction signal processing system of the present invention further includes a circuit for detecting changes in the light beam intensity during recording and the temperature on the recording medium, and updating the calculation of the pulse interval adjustment amount and recording power during recording. Has a system.
This circuit system comprises an edge interval measuring circuit 270,
And a recording condition determination circuit 271. First, the reproduced binary signal 277 passes through the edge interval measuring circuit 270, and its pulse interval and gap interval are measured. The measurement result is input to the recording condition determination circuit 11, where the change amount of the light beam intensity during recording and the temperature change amount on the recording medium are separated and detected, and the result is transmitted to the controller 272.
This recording condition judging circuit operates in a recording condition judging mode instructed by the controller at predetermined time intervals other than during normal information recording / reproducing. FIG. 28 shows the flow of the recording condition determination mode.
During operation of the present system, a predetermined time interval is monitored by the controller 272 in the present system, and this mode is started at each time interval (20).
31). First, at the beginning of this mode, the present system is set in a busy state so that a normal recording / reproducing operation is not accepted (2032). If there is any work (recording / reproducing) currently being processed by the present system, the processing is performed. It waits for the end (2033).
Next, the light spot is moved to a dedicated area for recording and reproducing a predetermined recording signal for checking recording conditions (2034). This area is set at a plurality of locations having different rotation radii per recording medium.
When the movement is completed, recording is performed on a recording medium using a predetermined recording signal for checking recording conditions. Then, the record mark is reproduced (2035). At this point, the edge interval measurement circuit 270 and the recording condition determination circuit 271 operate in response to a command from the controller. The determination results (2036, 2038) are transmitted to the controller 272, and the controller changes the light beam intensity during recording (2037, 2041) according to the determination results.
Also, the operation of changing the pulse interval adjustment amount during recording is performed.
For example, if the result of the determination indicates that the light beam intensity at the time of recording has changed to a value greater than the set value and that the amount of change has exceeded the allowable amount, the light beam intensity at the time of recording is determined by the step size. ΔP is reduced. Similarly, if it is determined in the determination result that the light beam intensity at the time of recording has changed to a value smaller than the set value, and it is determined that the amount of change has exceeded the allowable amount, the light beam intensity at the time of recording is increased by the increment ΔP. Let it.
If the result of the determination indicates that the temperature on the recording medium has changed to a value higher than the assumed value and that the amount of change has exceeded the allowable range, if the change in the light beam intensity during recording has occurred, If the light beam intensity at the time of recording exceeds the range that can be dealt with by changing the light beam intensity at the time of recording, if the light beam intensity at the time of recording exceeds the range that can be handled, Along with the operation of decreasing the step amount ΔP of the light beam intensity, the pulse interval adjustment amount at the time of recording is changed (2039). Similarly, if the determination result indicates that the temperature on the recording medium has changed to a value lower than the expected value, and that the amount of change has exceeded the allowable range, if the change in the light beam intensity at the time of recording is taken, the response will be taken. If the range is possible, the light beam intensity at the time of recording is
If the value exceeds the range that can be dealt with by changing the light beam intensity at the time of recording, the increment of the light beam intensity at the time of recording △ P and the pulse interval adjustment at the time of recording are performed. The amount is changed (2039).
If it is determined in the result of the determination that each variation does not exceed the allowable range, no change regarding the recording condition is performed.
In response to the above-described determination result, a corresponding operation is performed, a signal in the dedicated recording area is deleted, the busy state of the system is released, and the system returns to the normal information recording / reproducing mode. .
The time interval at which the recording condition determination mode is generated is determined by the change in the light beam intensity during recording and the time required for the temperature change on the recording medium to change. For example, regarding the light beam intensity during recording,
It must be set within a time interval that does not change more than the change step width ΔP at most.
Referring back to FIG. 27, the signal recording system in this embodiment will be described. When recording information, the recording information is adjusted by the modulation circuit 273 so as to match the characteristics of the optical information recording system.
Code modulation is performed. The edge position of the code-modulated recording signal is adjusted by the edge position adjustment circuit 274 and the edge position adjustment tables 275 and 276 according to the edge interval information immediately before. Then, the adjusted recording signal is input to the laser driver circuit 17, and the laser intensity in the optical pickup 2 is modulated according to the signal to record information on the disk 1. The edge position adjustment tables 275 and 276 are provided by the edge position adjustment table switching circuit 278 when it is determined that the amount of edge adjustment needs to be changed as a result of the recording condition determination mode and when the recording linear velocity changes. Its contents are changed.
In FIG. 27, an optical disk 1, a spindle motor 2, an optical pickup 3, an amplifier 10, an equalizing circuit 11, a binarizing circuit 13, a PLL circuit 14, and a demodulating circuit 1
7, the modulation circuit 273, and the laser driver circuit 7 may have the same configuration and function as those used in the conventional optical disk device, and detailed description thereof will be omitted.
Hereinafter, other components will be described.
FIG. 29 is a diagram showing a configuration example of the edge interval measuring circuit 270 in FIG.
The reproduced binarized signal 277 output from the binarizing circuit 13 is also input to the impulse signal generating circuit 701. The impulse signal generation circuit 701 outputs an impulse-like signal waveform at each timing when the polarity of the input signal changes, and this output signal is sent to the recording condition determination circuit 271 and the A / D converter 702 as a signal representing the polarity inversion timing. Is entered.
On the other hand, the reproduced binary signal 277 is also input to an integration circuit 703 composed of an amplifier. The "H" level of the reproduced binary signal is set to V
When the H and “L” levels are VL, − (VH + VL) /
An integration reference signal 704 representing a level of 2 is also input.
The integration circuit 703 outputs the reproduced binary signal 27
The signal of the difference between the reference signal and the reference signal 7 is output and input to the A / D converter 702.
A signal from the controller is input to flip-flop 709. This flip-flop 7
A signal indicating the polarity inversion timing is also input to 09 as a clock signal. The output of the flip-flop 709 detects the first rise of the reproduced binary signal 277 from the start of the edge interval measurement, switches the analog switch 710 during the interval measurement period, and operates the integration circuit 703.
The A / D converter 702 converts the output signal of the integration circuit 703 into a digital signal by using a signal representing the timing of the polarity inversion as a timing clock for performing a digital conversion operation. The conversion result is output as a polarity reversal interval signal and input to the recording condition determination circuit 271. The conversion accuracy of the A / D converter 702 has sufficient accuracy as an output value of the pulse interval adjustment amount, and quantization accuracy and the number of bits that do not cause overflow.
Next, the edge interval measuring circuit 270 shown in FIG.
Will be described with reference to FIG. Reproduction binarized signal 27
Reference numeral 7 denotes an output signal of the binarization circuit 13, which takes an "H" or "L" level depending on the presence or absence of a recording mark at the irradiation light spot position on the recording film surface. The reproduced binarized signal 277 passes through an impulse signal generation circuit 701 and becomes a signal indicating a polarity inversion timing for generating an impulse waveform at a timing when the polarity changes, and is used as a trigger signal in the A / D converter 702. You.
In the integrating circuit 703, the reproduced binary signal 277
Are calculated and output. This integration circuit 7
03 generally indicates an output signal Y (t) when its input signal is X (t).
[Number 20] Y (t) = ∫ 0 X (τ) dτ + Y (0) ... ( number 20) is obtained. 25. That is, the output signal Y (t) has its initial value (the output signal level at the time when the edge interval measurement circuit starts operating) Y (0) becomes 0 by the operation of the analog switch 710. The pulse interval Pr , Pr ,...
Using r , Gr ,..., the output signal level Vo of the integration circuit 703 is such that the polarity of the reproduced binary signal 7 is “
At the time of inversion from “L” to “H”,
[Equation 21] Vo = A (-Pr  + Gr  -Pr  + Gr  +... -Pr [i] + Gr [i]) (Equation 21) The polarity of the binary signal 277 changes from "H" to "H".
At the time of inversion to L "
Vo = A (−Pr  + Gr  −Pr  + Gr  +... -Pr [i]) (Equation 22) Here, A in the above equation is a constant determined by the amplification factor of the integrating circuit 703. That is, the output signal level at this time is determined by the pulse interval of the reproduced binary signal 277.
It shows the result of integrating pulse intervals when the “H” level is represented by a negative value and the “L” level is represented by a positive value.
The A / D converter 702 converts the integrated signal level at that time into a digital value, and inputs the conversion result to the recording condition determination circuit 271. That is, the output is given by Equations 21 and 22,
[Equation 23] B (-Pr  + Gr  -Pr  + Gr  +... -Pr [i] + Gr [i]) (Equation 23)
[Expression 24] B (-Pr  + Gr  -Pr  + Gr  +... -Pr [i]) (Expression 24) (B is a constant)
FIG. 301 shows an example of the configuration of the recording condition determination circuit 711 in FIG.
In this circuit, each Pr [i] in FIG.
The calculation of −Gr [i] and the calculation of the sum of the repetition signals are performed, and the calculation results are transmitted to the controller 272.
Latch circuits 901 and 902 and subtraction circuit 90
In equation (3), equation 2 sent from the edge interval measuring circuit 10 is used.
3 and the value of each B (Pr [i] -Gr [i]) from the edge interval data represented by Expression 24. A reproduced binary signal 277 is input to the latch circuit 901 as a signal for trigger timing, and the edge interval data is sampled and held at the rising edge thereof. That is, when the reproduced binary signal 277 rises, the data represented by Expression 23 is held and output. In the latch circuit 902, the data is delayed by one trigger.
The subtraction circuit 903 subtracts the output of the latch circuit 901 from the output of the latch circuit 903 of the edge interval data, and outputs the result. Since the output of the latch circuit 902 and the output of the latch circuit are the result represented by Expression 23 shifted by one trigger timing, B (Pr [i] -Gr [i]) is obtained from the output of the subtraction circuit 903. ing.
Addition circuit 904 and shift register 9
05, each B (Pr [i] -Gr) in repeated data
The sum is calculated for each [i]). The number of stages of the shift register 905 is designed to be equal to the number of pulses in one cycle of the recording signal shown in FIG. 25, and an output line is output for each stage and sent to the controller. When the reproduction signal 402 has been read to the end, the output result at each stage of the shift register indicates the B
(Pr [i] -Gr [i]).
Using these results, it is checked whether the light beam intensity during recording and the temperature of the recording medium have changed based on the criteria shown in FIG.
FIG. 32 shows an example of the configuration of the edge position adjustment circuit 274 and the edge position adjustment table 275 shown in FIG.
In this circuit, the functions Cf () and Ce () in Expressions 18 and 19 are obtained by referring to the contents of the edge position adjustment tables 15 and 16 composed of storage elements such as RAM. That is, when obtaining F [i],
It is an element of the first and second parameters in the function Cf () by the address signal line input to the edge position adjustment table 275. Pulse / gap interval L of recording signal 301
[I-1], B [i-1], and edge position adjustment amounts F [i-1] and E [i, which are conversion results immediately before obtaining F [i].
-1] is input as a function value from the data signal line. Similarly, when E [i] is obtained, the pulse / gap of the recording signal 301, which is the element of the first and second parameters in the function Ce (), is determined by the address signal line input to the edge position adjustment table 16. Edge position adjustment amounts E [i-1], F, which are conversion results immediately before obtaining intervals B [i-1], L [i], and E [i].
By inputting the quantity representing [i], it is output as a function value from the data signal line.
The counter circuits 1001 and 1002 detect how many pulse / gap intervals of the signal transmitted from the modulation circuit 273 correspond to the number of basic clock intervals of the modulation signal, and connect the address lines of the edge position adjustment table to the address lines. Has become. Also, the latch circuits 1003, 1004, 100
5 and 1006 are used to adjust the timing of each address signal line input to the edge position adjustment table 275 and the shift register circuits 1007 and 1008 are used to adjust the timing between the modulation signal and the edge position adjustment amount. ing. The selector circuit 1009 is a circuit that alternately switches the rising and falling edge position adjustment amounts.
Reference numeral 9 denotes a circuit for delaying the edge position by the edge position adjustment amount and adjusting the edge position. Therefore, this output signal is input to the laser driver circuit 7 as the adjusted signal 302.
FIG. 33 shows an example of the configuration of the edge position adjustment table switching circuit 18 in FIG.
This circuit switches the contents of the edge position adjustment table in accordance with the change in the recording linear velocity and the temperature of the recording medium, and adjusts the edge position for each recording linear velocity in the range of use and the temperature of the recording medium. It is composed of a conversion table data buffer 1102 in which an amount of data is stored, and a circuit for controlling the switching operation.
As a result of the detection in the recording condition determination mode, when it is determined that the content of the edge position adjustment table needs to be changed, and when the light spot moves and the linear velocity changes, a table change command is issued from the controller 272. The signal is input to the counter circuit 1101, and the change of the contents of the edge position adjustment tables 275 and 276 is started. In this content change operation, first, the moving speed of the light spot on the recording medium and the temperature of the recording medium detected in the recording condition determination mode are input to the conversion table data buffer 1102, and the conversion table data buffer 1102 is input. , Which edge position adjustment table is selected. Then, for each address number input from the counter circuit 1101, the conversion table data buffer 11
02, each edge adjustment amount is transmitted and stored in each conversion table. One of the output signals of the counter circuit is used as a table switching signal for selecting one of the edge adjustment amount tables 275 and 276, and the remaining signals are the conversion table data buffer 1102 and the edge signal. The position adjustment circuits 275 and 276 are used as address signals.
The preceding is an explanation of an embodiment of the present invention. By using the recording pulse edge adjustment amount calculation method, it is possible to eliminate a change in edge position in a reproduced waveform due to thermal interference, which occurs due to a different recording pattern in the same recording pulse.
As the dedicated area used for the recording condition measurement, a plurality of locations including the inner circumference side, the outer circumference side, and between them are used. The area may be specially provided or a general data recording area. In the latter case, if recording data already exists in that area, another free area is used, or the information written in that area to use that area is stored in another memory such as a memory in the temporary controller. The process of evacuating to the location is performed.
The present invention is a rewritable, and is a recording method using heat, the principle of which is any information recording method and a control method of recording conditions such as recording power and recording pulse interval applicable to a recording medium. A recording method and a recording medium which have a particularly high heat diffusion effect and are sensitive to recording conditions, that is, a recording power, an environmental temperature, a configuration of a recording medium, and a slight change in the characteristics of a recording apparatus, which appear as a difference in recording characteristics. In the case of, it is an indispensable technique for ensuring the reliability of the recorded data. For example, this technique is important for ensuring practicality in a magneto-optical disk, an overwritable magneto-optical disk utilizing exchange coupling force, an optical disk utilizing an overwritable phase change, and the like.
As described above, according to the present invention, a test recording is performed, a result thereof is arithmetically processed, a signal for recording control is obtained, and based on the signal, a desired position can be controlled by an edge position adjusting circuit.
According to this signal recording / reproducing method, it is possible to eliminate the variation in the edge position of the reproduced signal due to thermal interference. In addition, in order to cope with changes in the light beam intensity during recording and changes in the temperature of the recording medium, optimal recording conditions are always realized, and higher-density recording using mark length recording can be performed during production. It can be easily realized without strict adjustment, and greatly improves the reliability of recording data.
(Embodiment 8) This embodiment is a method of realizing high-density recording by changing the recording density according to the disk position and recording.
In a recording method such as MCAV in which the rotational speed of the disc-shaped recording medium is kept constant and the linear velocity changes as the recording radial position changes, data can be recorded with high reliability while securing the capacity. It is desired that the magnitude of the phase jitter be equal over the inner and outer circumferences of the disc in order to record and reproduce the data.
In the above-described edge recording, phase jitter is caused by phase fluctuation caused by random noise such as noise of a disk medium, laser noise, and amplifier noise.
The recording domain length is largely classified into two types: an edge shift in which the edge position of the domain changes due to a difference in the length of the recording domain depending on the pattern and a thermal interference between the patterns. Since the medium of a magneto-optical disk has good thermal conductivity, especially at the inner periphery where the linear velocity is low, the phase of the next information domain to be recorded is shifted due to the influence of the heat of the pulse recorded immediately before. , Larger than the phase fluctuation. This makes it impossible to accurately reproduce information.
Considering the method of determining the linear density when a substantially concentric track of the magneto-optical disk is divided into zones composed of a plurality of tracks as shown in FIG. 40, the linear recording density in each zone is the same. Rmin is the radial position of the innermost zone of the magneto-optical disk, Ln is the linear density of the nth zone from the inner side, Ni is the number of sectors on the innermost zone, B is the number of data bytes per sector, p is the track pitch, and If the number of tracks is M and the data utilization efficiency is η, the capacity of the innermost zone is
2π × Rmin × Li × η = Ni × B (Equation 25) In the n-th zone,
[Formula 26] 2π × (Rmin + n × M × p) × Ln × η = (Ni + n) × B (Formula 26) The difference between the linear density of the nth zone and the linear density of the (n + 1) th zone is
Ln + 1−Ln = n (B−2π × M × p × Ln × η) / 2 × π (Rmin + M × p) × η (Expression 27) Therefore, B and 2π × M × p × Ln × The linear density can be controlled by the magnitude relationship of η. That is, in the present invention, it is desired to improve the linear density on the outer peripheral side rather than on the inner peripheral side where the phase shift is large.
(28) The number of tracks M and the track pitch p are selected such that Ln <B / (2π × M × p × η) (Expression 28).
For example, one per zone using 2-7 modulation
By increasing the number of sectors / tracks, the track pitch is set to 1.6 microns, and the innermost circumference of the recording radius is set to 67.9 m.
m, and the number of innermost sectors is 52, FIG.
It changes like 6. Here, instead of the linear density, the shortest pit length of 2-7 modulation is taken on the vertical axis. The smaller this is, the higher the linear density is.
From the viewpoint of the recording capacity, the above investigation results show that when the linear density at the recording radius position is controlled such that the linear density is increased at the outer periphery and decreased at the inner periphery as shown by a solid line 1100 in FIG. The contribution of the storage capacity is as shown by the solid line 2100 in FIG. FIG. 35 shows the capacity per track obtained by multiplying the length of the circumference with respect to the radial position by the linear density. When this is integrated from the radii Ri to Ro, the total storage capacity is obtained. Dotted lines 1200 and 220 in FIGS.
0 is a case where the linear density is kept constant, and as can be seen from FIG. 35, even if the linear density is reduced on the inner peripheral side, the capacity contribution on the inner peripheral side is small, so that the total storage capacity is reduced. It is understood that the influence is small. Specifically, FIG.
There is a method of changing the linear density for each of the zones 1401, 1402, 1403 shown in FIG.
In realizing an apparatus having a large storage capacity by combining the edge recording using the medium of the magneto-optical disk and the MCAV method according to the present invention, the phase fluctuation amount representing the data reliability can be made substantially equal between the inner and outer circumferences, and A decrease in storage capacity can be suppressed.
(Embodiment 9) This embodiment relates to providing an area for test recording in a disc to obtain control parameters required for performing recording control.
The details of the present invention will be described using an embodiment. First, a schematic diagram showing a cross-sectional structure of the manufactured disk is similar to FIG. The manufactured disk was made of SiNx (75 nm) 51 and ΔTb on a polycarbonate substrate 50.
FeCoNb (30 nm) 52, ≠ SiNx (20 n
m) 53, ΔNi (30 nm) 54, ΔAl (30n)
m) 55 are sequentially laminated. The production of the disk was performed by a sputtering method. The sputtering conditions at that time were as follows: after evacuating to 10 −7 Torr or less,
A silicon nitride film 51 was formed on a polycarbonate disk substrate 50. Using pure Si as a target and an Ar / N 2 mixed gas as a discharge gas, input RF power density: 6.6 mW / cm 2 , discharge gas pressure: 10 mTorr
Was performed to form a film having a thickness of 75 nm. Subsequently, a TbFeCoNb magneto-optical recording film 52 was formed. Using a TbFeCoNb alloy as a target and a high-purity Ar gas as a discharge gas, input RF power density: 4.4 mW / cm 2 , discharge gas pressure: 5 mTorr
To form a film having a thickness of 30 nm. Again, a silicon nitride film 53 was formed.
Pure Si was used as the target, and Ar /
RF power density: 6, using N 2 mixed gas.
Sputtering was performed at 6 mW / cm 2 and a discharge gas pressure of 10 mTorr to form a film having a thickness of 20 nm.
Next, formation of the Ni film 54 will be described. Ni was used as the target, and high-purity Ar gas was used as the discharge gas. Sputtering was performed at a supplied RF power density of 3.3 mW / cm 2 and a discharge gas pressure of 15 mTorr to form a film with a thickness of 30 nm. Finally, the formation of the Al film 55 is performed. Using Al as a target and high-purity Ar gas as a discharge gas, input RF power density: 3.3 mW / c
Sputtering was performed at m 2 and a discharge gas pressure of 15 mTorr to form a film having a thickness of 30 nm. And finally, Al
This is the formation of the film 55. Using Al as the target and high-purity Ar gas as the discharge gas, the input RF power density:
Sputtering was performed at 3.3 mW / cm 2 at a discharge gas pressure of 15 mTorr to form a film having a thickness of 30 nm.
The film surface of the magneto-optical disk produced in this manner was coated with an ultraviolet-curable resin, and
The two disks were bonded with an adhesive to form a magneto-optical disk. Here, the structure of the disk used is merely an example, and the effects of the present invention are not affected by the structure of the disk. This disc has a single-layered recording film, but is also effective for an overwritable optical disc using the exchange coupling function, and also for recording control of an optical disc using a phase change. Needless to say, it is effective.
FIG. 39 shows a plan view of the disk thus manufactured. On the other hand, when the disk drive is started, the test pattern 21 shown in FIG.
Was recorded on the recording control test track 1400 shown in FIG. Then, by measuring the change in the signal amplitude of the reproduced signal, a change in the magnetic domain shape formed due to an external factor was detected. Based on this result,
The user data was recorded in the recording area by controlling at least the laser power at the time of recording, the pulse width of the recording, or the shape of the recording pulse.
FIG. 38 shows a schematic diagram of the shape of the recording magnetic domain obtained at that time. If recording is performed without control, a tear-shaped magnetic domain is formed, the width is increased because the magnetic domain width is not controlled, or the magnetic domain length is increased or shortened because the magnetic domain length is not controlled, and pit edge recording is performed. Attempting to do so could result in an error. A major cause of these changes is fluctuations in the use environment temperature. Therefore, when the disk drive is started or the disk is inserted, recording is performed on the recording control test track 1400 using the test pattern,
The problem was solved by detecting the use environment temperature by reproducing the information and feeding back the result to the setting of the recording condition and performing the recording in consideration of the environment condition.
As a result, the size of the domain recorded on the disk 1 was always constant even when the environmental temperature changed.
As a result, high-density recording is possible. Also, if there is a variation in recording sensitivity between the media, an error may occur because the size of the domain formed for each disc is different. According to the present invention, the test pattern stored in the disk drive is recorded in advance on the test track provided by the present invention, the recorded data is reproduced, and the obtained signal amplitude is measured, whereby the disc-to-disk It was able to absorb the effects of environmental temperature changes, including variations in the temperature. Here, control information based on the test pattern was finely collected when the disk drive was started and when the disk was inserted.
According to the present embodiment, the recording area of the disk 1 is divided into a plurality of zones 1401, 1402, 140 in advance.
3 and an area 1400 for collecting information for performing recording control for each zone is provided, and recording / reproduction is performed using a test pattern there. Can be corrected. This is because at least each zone 1401, 140
By providing a test track for every 2,1403,
This problem could be solved. As a result, ultrahigh-density optical recording was realized. In addition, if a test area is provided for each track, test recording is performed in the same place where test recording has already been performed in order to prevent deterioration of the medium of the test track where more precise correction can be performed. It is effective to prevent the test recording from being performed continuously or to prevent the test track from being rewritten unbiasedly.
Further, as described above, the inner circumference, the middle circumference,
When test recording is performed on the outer test track 1400, each zone 1401, 1402, 140
The recording / reproducing characteristics of the disk in the zone where the test recording is not performed can be removed by storing the recording / reproducing characteristics in the storage means in the storage means.
The present invention relates to an optical disk apparatus for recording / reproducing / erasing a digital signal of a mark length recording system on an optical recording medium such as an optical disk, and eliminates a change in an edge position of a reproduced signal due to thermal interference between pits. In addition, it is possible to provide a method of reducing a change in edge position due to a change in external environmental conditions.
FIG. 1 is a block diagram for explaining an apparatus of the present invention.
FIG. 2 is a flowchart illustrating the operation of one embodiment.
FIG. 3 is a conceptual diagram illustrating the relationship between a recording method and recorded marks according to an embodiment of the present invention.
FIG. 4 is an explanatory conceptual diagram of a relationship between a recording method and recorded marks according to an embodiment of the present invention.
FIG. 5 is an explanatory conceptual diagram of a test write recording pattern according to the present invention.
FIG. 6 is a block diagram of a test write control signal detection circuit according to the present invention.
FIG. 7 is an explanatory diagram showing a relationship between a thermal time constant and a temperature error after thermal interruption.
FIG. 8 is a waveform chart for explaining one embodiment of a recording waveform.
FIG. 9 is a waveform chart for explaining another embodiment of a recording waveform.
FIG. 10 is a waveform chart showing a recording signal waveform.
FIG. 11 is a waveform chart showing a recording signal waveform.
FIG. 12 is an explanatory conceptual diagram of a relationship between a reproduction signal waveform and a recorded mark.
FIG. 13 is a graph showing the pattern dependence of edge shift.
FIG. 14 is a waveform chart showing a recording signal waveform.
FIG. 15 is a waveform chart showing a recording signal waveform.
FIG. 16 is an explanatory conceptual diagram of a relationship between a reproduction signal waveform and recorded recording marks.
FIG. 17 is a graph showing the pattern dependence of edge shift.
FIG. 18 is a graph showing a recording signal waveform.
19A and 19B are a graph and a circuit diagram illustrating an example of a laser driving circuit.
FIG. 20 is a diagram without a flow of a test writing procedure.
FIG. 21 is a sectional view of a magneto-optical disk.
FIG. 22 is a waveform chart showing the shape of a recording pulse waveform.
FIG. 23 is a schematic diagram illustrating a state in which an edge position shifts due to thermal interference.
FIG. 24 is a schematic diagram for explaining how to adjust the position of each edge of a recording signal using information on the amount of edge shift to suppress the influence of edge shift;
FIG. 25 is a waveform chart showing an example of a recording signal pattern for recording condition measurement.
FIG. 26 is a graph illustrating means for separately detecting a change in the light beam intensity during recording and a change in the temperature of the recording medium from the measurement result.
FIG. 27 is a block diagram showing a configuration of an embodiment.
FIG. 28 is a flowchart of a recording condition determination mode.
FIG. 29 is a block diagram showing a configuration example of an edge interval measurement circuit.
FIG. 30 is an explanatory conceptual diagram for explaining the operation of the edge interval measuring circuit.
FIG. 31 is a circuit diagram showing a configuration example of a recording condition determination circuit.
FIG. 32 is a block diagram illustrating an example of a configuration of an edge position adjustment circuit and an edge position adjustment table.
FIG. 33 is a block diagram showing a configuration example of an edge position adjustment table switching circuit.
FIG. 34 is a graph showing a relationship between a recording radius position and a linear density.
FIG. 35 is a graph showing the relationship between the recording radius and the capacity contribution.
FIG. 36 is a graph showing a relationship between a recording radius and a shortest domain length.
FIG. 37 is a waveform diagram of a test pattern.
FIG. 38 is a schematic view showing a recording magnetic domain shape.
FIG. 39 is a plan view of the optical disc of the present invention.
FIG. 40 is a waveform chart showing a minimum change length.
DESCRIPTION OF SYMBOLS 1 ... Optical disk, 3 ... Trial writing means, 4 ... Encoder, 7 ...
Light source driving means, 8 light source, 9 detector, 11 waveform processing means, 13 pulsing means, 15 discriminator, 16 comparison means, 17 decoder.
──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Maeda 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Seiichi Mita 2880 Kozu, Odawara City, Kanagawa Prefecture Inside Odawara Plant, Hitachi, Ltd. (72) Inventor Kazuo Shigematsu 2880 Kozu, Kozuhara City, Odawara City, Kanagawa Prefecture Inside Odawara Plant, Hitachi Ltd. JP-A-3-185628 (JP, A) JP-A-64-37745 (JP, A) JP-A-63-271724 (JP, A) JP-A-3-22223 (JP, A) JP-A-2-5221 (JP JP-A-4-30327 (JP, A) JP-A-4-10220 (JP, A) JP-A-3-237635 (JP, A) (58)査the field (Int.Cl. 7, DB name) G11B 11/105
- A light source for irradiating the optical disk with a light beam; an encoder for converting an information signal to be recorded into a code sequence; a modulation of the light beam in accordance with the code sequence; A light source driving unit that records a code string as a recording mark by at least one of thermal interference, a detector that photoelectrically converts light from the optical disc to obtain an electric signal waveform, a waveform processing unit that performs waveform processing on the electric signal waveform, Pulsing means for converting a signal from the waveform processing means into a pulse signal, a discriminator for detecting a code string recorded on the optical disc from the pulse signal, and a decoder for decoding the code string from the discriminator into an information signal The optical disk apparatus having the above structure, wherein the test is performed by modulating the light beam with a test signal and irradiating the modulated optical pulse train on the optical disk Test writing means for forming a pattern; wherein the optical pulse train is one unit of a recording pulse train for forming one recording mark having a pulse of a power level of Pw, and a power level of Pas immediately before the one unit of the recording pulse train. The area and the rear side of the one unit recording pulse train
r power level region, and the above Pw, Pas, P
r is a relation of Pw>Pas> Pr, means for reproducing and evaluating the test pattern, and control means for controlling a power level of the Pas of the light beam forming the test pattern based on the evaluation result. An optical disk device comprising:
- 2. The optical disk apparatus according to claim 1, wherein said test pattern is encoded by an encoder and recorded.
- 3. An optical disk apparatus according to claim 1, further comprising a changeover switch for inputting said electric signal waveform to said pulsing means without passing through said waveform processing means.
- 4. The optical disk apparatus according to claim 1, wherein the optical disk is divided into a plurality of zones having different recording conditions in a radial direction, and each zone has an area for recording the test pattern.
- 5. The light source driving means according to claim 1, wherein a plurality of unit drive circuits each comprising a switch means and a current source in series with the switch means are arranged in parallel, and one constant current source is arranged in series with each of the unit drive circuits. A light source is connected in series with the constant current source and in parallel with the unit drive circuit, the current sources of the plurality of unit drive circuits are configured to flow currents of different values, and the switch means controls the control signal based on the code string. 2. The optical disk device according to claim 1, wherein a current value for driving the light source is controlled by operating the light source.
- 6. At least one current source of the unit driving circuit
6. The optical disk device according to claim 5, wherein one of the optical disks is variable in current.
- Wherein said switching means is an optical disk apparatus according to claim 5, wherein the element for switching an npn type.
- 8. An information signal to be recorded is converted into a code train, a light beam is modulated into a light pulse train in accordance with the code train, and the light pulse train is irradiated on a recording medium. The code string is recorded as a recording mark by at least one of the recording marks, light from the recording medium is photoelectrically converted to obtain an electric signal waveform, the electric signal waveform is waveform-processed, and the waveform-processed electric signal is converted into a pulse signal. And an optical information recording / reproducing method for detecting a code string recorded on the recording medium from the pulse signal and decoding an information signal of the detected code string. Is modulated to an optical pulse train to form a test pattern on the recording medium. The optical pulse train is a unit of one unit for forming one recording mark having a pulse of a power level of Pw. P and recording pulse train, and the one unit recording pulse train power level in the region of Pas just before the, behind the recording pulse train of the 1 unit
r power level region, and the above Pw, Pas, P
r has a relation of Pw>Pas> Pr, reproduces the test pattern, compares it with the test signal, and controls the power level of Pas constituting an optical pulse train forming the test pattern based on the result. An optical information recording / reproducing method, characterized in that:
- 9. Each time the recording medium is exchanged, the light beam is modulated into an optical pulse train by the one information signal to form a test pattern on the recording medium, and the test pattern is reproduced to reproduce the test signal. 9. The optical information recording / reproducing method according to claim 8, wherein an optical pulse train for forming the test pattern is controlled based on the result as compared with the above.
- 10. The optical information recording / reproducing method according to claim 8, wherein said test pattern includes a longest code and a shortest code.
Priority Applications (7)
|Application Number||Priority Date||Filing Date||Title|
|JP00388793A JP3345932B2 (en)||1992-02-13||1993-01-13||Optical disk device and optical information recording / reproducing method|
Applications Claiming Priority (2)
|Application Number||Priority Date||Filing Date||Title|
|JP00388793A JP3345932B2 (en)||1992-02-13||1993-01-13||Optical disk device and optical information recording / reproducing method|
|US08/436,490 US7227818B1 (en)||1991-11-11||1995-05-08||Magneto-optical data recording/reproducing method|
|Publication Number||Publication Date|
|JPH05290437A JPH05290437A (en)||1993-11-05|
|JP3345932B2 true JP3345932B2 (en)||2002-11-18|
Family Applications (1)
|Application Number||Title||Priority Date||Filing Date|
|JP00388793A Expired - Lifetime JP3345932B2 (en)||1992-02-13||1993-01-13||Optical disk device and optical information recording / reproducing method|
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|JP (1)||JP3345932B2 (en)|
Families Citing this family (12)
|Publication number||Priority date||Publication date||Assignee||Title|
|DE69604209T2 (en) *||1995-01-31||2000-03-23||Canon Kk||Test method for a pit length modulation-based recording method and optical information recording / reproducing apparatus using this test method|
|JP2981645B2 (en) *||1995-09-19||1999-11-22||富士通株式会社||Magneto-optical recording method|
|JP3218368B2 (en) *||1996-09-17||2001-10-15||富士通株式会社||Data playback device|
|JP3076033B1 (en)||1998-09-14||2000-08-14||松下電器産業株式会社||Optical information recording / reproducing apparatus and information recording medium|
|US6650607B1 (en)||1998-10-12||2003-11-18||Hitachi, Ltd.||Information recording method, information recording medium, and information recording apparatus|
|US7082566B2 (en)||2001-11-09||2006-07-25||Kabushiki Kaisha Toshiba||Signal quality evaluation method, information recording/reproducing system, and recording compensation method|
|US6954415B2 (en)||2002-07-03||2005-10-11||Ricoh Company, Ltd.||Light source drive, optical information recording apparatus, and optical information recording method|
|JP2005243053A (en) *||2003-03-24||2005-09-08||Ricoh Co Ltd||Recording/reproducing method and recording/reproducing apparatus for dye-based write-once type dvd medium|
|CN100414619C (en) *||2003-03-24||2008-08-27||株式会社理光||Optical recording medium,reproducing method and apparatus|
|JP2007220264A (en) *||2006-02-20||2007-08-30||Tdk Corp||Method and device for recording information in super-resolution optical recording medium|
|JP4800429B2 (en) *||2010-03-11||2011-10-26||パナソニック株式会社||Optical information recording method and optical information recording apparatus|
|US10354687B2 (en)||2016-01-21||2019-07-16||Sony Corporation||Recording adjustment device, recording adjustment method, and program|
- 1993-01-13 JP JP00388793A patent/JP3345932B2/en not_active Expired - Lifetime
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