JP2005122835A - Optical disk control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that high speed recording and reproduction require use of a high performance DSP working at high frequencies thus increasing the cost and power consumption because the control cycle steps are not enough in arithmetic operation of a conventional DSP although the control band has to be increased for the focus control and tracking control. <P>SOLUTION: Processing in a high frequency band is made feasible at high speed in the conventional DSP by carrying out focus control and tracking control without the arithmetic operations of the sub-focus error signals and sub-tracking error signals that become less important depending on the controlled state. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to writing control to an optical disk represented by DVD-R, DVD + R, DVD-RW, DVD + RW, and the like capable of groove recording.

  Today, optical discs such as CDs (Compact Discs) and DVDs (Digital Versatile Discs) have become mainstream as recording media for storing video information, audio information, and other various types of information. The reason is that high-density recording is possible and desired data can be accessed at high speed.

  In a read-only optical disc, irregularities called pits are formed on a spiral or concentric track formed on the optical disc substrate, and follow the laser light emitted from the laser diode along the track. Then, the reflected light from the pit portion is detected by a photodiode, and information recorded on the optical disk is read according to the intensity of the reflected light. In contrast to this read-only optical disc, the recording type optical disc has a recording layer on the reflective layer.

  Hereinafter, the structure of the recordable optical disk base and the recording / reading method will be described with reference to FIG. FIG. 10 shows a part of the reflective layer and the recording layer of the optical disk substrate. 91 is a recording layer portion without recording, 92 is a recording layer portion with recording, 93 is a reflection layer, 94 is incident light of laser light emitted to the optical disc, and 95 is no recording. Reference numeral 96 denotes reflected light of the laser light emitted from the recording layer 93, and reference numeral 96 denotes reflected light of the laser light emitted from the recording layer 92 with recording. In this case, the reflected light 96 that has passed through the recording layer 92 with recording is reflected with a higher reflectance than the reflected light 95 that has passed through the recording layer 91 without recording. The reason will be described below.

  In a recordable optical disc, a recording layer is formed on a reflective layer, and this recording layer has a property of changing properties by a laser, and information is written on the disc using this property. Specifically, the change in the properties of the recording layer refers to a change in laser absorption or refractive index. If the laser absorptivity of the recording portion is reduced, the reflectance of the optical disk is increased during reproduction. Further, when the refractive index of the recording layer changes, the wavelength (phase) of the laser that passes through the recording portion during reproduction changes, and it appears to be equivalent to an uneven reflection film. Information is written by changing the apparent reflectance from the reflective film. Note that the laser at the time of reproduction may use a laser whose output is lower than that at the time of recording at the time of reproduction because the recorded contents may be lost at every reading when the output is exactly the same as that at the time of recording.

  Also, there are recording type optical discs that can be recorded only once and those that can be rewritten. For optical discs that can be recorded only once, organic dyes of azo cyanine are used in the recording layer. When this dye is irradiated with a laser that is red visible light, the dye absorbs this laser light well. Therefore, the reflectivity from the reflective film apparently changes and information is written. This dye-based material is chemically changed to change its color and cannot be restored to its original state, so that recording can be performed only once. On the other hand, a technology called phase change recording is used for a rewritable optical disc. This is because an antimony-tellurium alloy film that is thin enough to transmit light to a certain degree is irradiated with a strong power laser in a short time, heated to a temperature at which the alloy melts, and then rapidly cooled to an amorphous state, which weakens the power. It uses the property of returning to the crystalline state of the group when heated at, and by mixing germanium with this alloy, a difference in the absorption rate of the laser is produced between the amorphous state and the crystalline state, and silver and indium are mixed. Mixing causes a difference in refractive index. That is, recording pits by melting point heating is information recording, and recrystallization is erasure. Since such a change can be repeated any number of times, a recordable optical disc having this recording film becomes a rewritable optical disc.

  In recording control on an optical disk using laser light as described above, it is necessary to output an optimum laser power in order to realize accurate information writing. However, the recording laser power for performing accurate recording is not always constant due to various factors. One of the factors is the characteristics of a laser diode that emits a laser in accordance with the drive current. That is, since the relationship between the drive current in the laser diode and the power of the emitted laser is affected by the temperature characteristics, the relationship between the drive current and the laser power is not necessarily constant, and in order to obtain a desired laser power, It is necessary to check the power of the laser that actually emits light and update the laser characteristics of the laser diode.

  Furthermore, in addition to the characteristics of the laser diode, there is a factor that there is a variation in sensitivity to laser light in the optical disk recording medium itself, which leads to different optimum laser power for recording for each disk. Since this sensitivity is also affected by the temperature during recording, it is necessary to actually perform laser recording as appropriate to obtain information on the optimum laser power.

  In addition, with the increase in the amount of information handled today, the recording medium is required to have a higher density than before. In order to satisfy this requirement, various improvement measures have been taken in the recording format even in the optical disk recording medium. As an example, a method of recording information at a high density by narrowing the track width on the optical disk substrate or narrowing the track pitch is employed. In this recording method, it is difficult to read the address information and control the rotation of the disc more accurately than in the past, so the tracks formed on the optical disc substrate are placed between the wobbled groove portion and the groove portions. The wobbled lands formed in a pair are formed spirally or concentrically from the innermost circumference toward the outermost circumference. Note that a recording method using a groove portion and a land portion is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-293926. The recording method will be described below.

  FIG. 11 is a diagram showing a conventional recording format for a groove portion and a land portion, and FIG. 12 is a diagram showing a structure on an actual optical disc substrate. In an optical disc, a groove portion 11 for recording information by being wobbled with a wobble signal having a predetermined frequency component and a land portion 12 positioned between adjacent groove portions 11 are spirally or concentrically formed on a disc substrate. Is formed. On the land portion, land prepits 13 having a predetermined phase relationship with the wobble signal and representing auxiliary information such as address information for recording data are formed.

  In the optical disc having the recording format shown in FIG. 11 and FIG. 12, the groove portion 11 in which data is recorded is previously divided for each sync frame as an information unit. A sync frame constitutes one recording sector, and a recording sector constitutes one error correction code. If the unit length corresponding to the pit interval defined by the recording format when recording data is T, one sync frame has a length of 1488T, and one sync frame The head portion of 14T in length is used as synchronization information 19 for synchronizing each sync frame.

  The land pre-pit 13 described above is recorded for each sync frame. A land pre-pit 13 indicating a sync signal in pre-information is formed on a land portion adjacent to an area in which sync information in each sync frame is recorded. One or two land prepits 13 may be formed.

When recording information on an optical disc having the above recording format, the phase of the wobble signal extracted from the wobbled groove portion is compared with the land prepit signal detected from the land prepit on the land portion. A phase difference signal is output, and the phase of the clock signal is adjusted based on the phase difference signal. In other words, the fluctuation on the adjustment axis of the clock signal generated based on the wobble signal whose influence of crosstalk cannot be ignored is corrected using the land pre-pits that are not affected by crosstalk. It is possible to generate a clock signal for recording synchronized with high accuracy, thereby realizing accurate information recording.
JP-A-10-293926

Incidentally, it is necessary to obtain an optimum laser power in order to execute information recording even in an optical disc having a track formed in a spiral shape or a concentric shape in the wobbled groove portion and land portion as described above. Conventionally, in order to obtain the optimum laser power, the laser characteristics of the laser diode are obtained by performing test light emission to the groove portion in the optical disc immediately before recording, before actual information recording. Further, the recording peak power is changed at the innermost circumference (PCA area) of the disk, and trial writing is actually performed on the disk, and a laser power suitable for each disk is detected. In this test, the laser diode drive current is changed during the 11T period, the bottom power and the peak power of the laser power output are detected with respect to the changed drive current, and the laser characteristics are obtained from the relationship. To do. FIG. 13 shows the relationship between the laser diode drive current and the laser power emitted accordingly. In FIG. 13, 34 is an output laser power waveform with respect to a time axis emitted for a recording test, and 35 is a detected laser power waveform in which the emitted laser light is detected by a front light detector. The output laser power waveform 34 is low when the drive current of the laser diode is x [A], and is high when the drive current is X [A]. The detected laser power waveform 35 is detected as a bottom power sample y [W] when the driving current of the laser diode is x [A], and is detected as a peak power sample Y [W] when the driving current is X [A]. The Based on the detected bottom power sample and peak power sample, laser characteristics relating to the relationship between the laser diode drive current and the laser power are calculated.
In addition, the recording peak power is changed in the innermost circumference, the recording is actually performed on the disk (test recording), the test signal recorded on the optical disk is read, and the asymmetry of the read RF signal is measured to thereby determine the sensitivity of the disk. Inspect and determine the best laser power for that disc. Specifically, the test light emission of 3T period and the test light emission of 11T period are performed, and the asymmetry of the disk is calculated based on the RF signal read from the data written in each test light emission. FIG. 14 is a diagram showing a method for determining an optimum laser power from asymmetry obtained from an optical disk. The asymmetry of the optical disk can be obtained by the equation (a). 3T-ave is the average value of the RF signal obtained from the data written by the test light emission for 3T period, 11T-pk is the peak value of the RF signal obtained from the data written by the test light emission for 11T period, and 11T- btm represents the bottom value of the RF signal obtained from the data written by the test emission for the 11T period. (B) is a graph showing the relationship between laser power and asymmetry. In equation (a), asymmetry corresponding to several samples of laser power is calculated, and the laser power when the asymmetry becomes 0 is detected as the optimum recording power.
Based on the laser characteristics of the laser diode obtained by the above test light emission and the asymmetry of the disk, the optimum drive current value to the laser diode for the disk can be obtained.

  However, in the control of optical discs, high-speed recording is progressing today, and high-speed recording has become mainstream in the field of optical disc recording. The above-described test for laser power output in the 11T period is originally performed in recording at a normal speed. When high-speed recording is performed, the test must be performed in a very short time in the 11T period. . For example, the 11T period at the normal speed is 429 ns, but is only 27 ns at the 16-times speed. As described above, in the test of a very short time, the laser power sampling with respect to the bottom power and the peak power of the driving current of the laser diode is not in time, and there is a problem that the laser characteristics cannot be acquired.

  In addition, the number of inferior discs with very large in-plane sensitivity, in-plane curtain film thickness, and in-plane distortion is increasing. That is, the characteristics differ greatly between the inner and outer circumferences of the disc. For this reason, even if test recording (trial writing) is performed only in the innermost circumference, the RF signal is detected, and the optimum recording power is determined, there arises a problem that it deviates from the true optimum power as it goes to the outer circumference of the disk.

  As a means for solving such a problem, it can be considered that the period for executing test recording on the optical disc is longer than 11T. For example, in 16 × speed recording, it is desirable to execute test recording for a period of 11T × 16 = 176T. However, if such a long period of test data is written in a groove portion prepared for information to be originally recorded, the recording capacity as an optical disc recording medium is naturally reduced.

  In the present invention, the test light emission is performed not on the groove portion that is originally prepared for information to be recorded but on the land portion having auxiliary information such as address information for recording data that is used at the time of recording. Thus, the optimum recording laser power corresponding to the characteristics of the disc can be obtained without cutting the information writable area in the groove portion.

  In the present invention, the focus is turned on with respect to the substrate surface of the disk during the test light emission. That is, by detecting a focus error signal at the time of laser output for testing and applying focus control, the time until the focus is turned on is shortened when the recording of actual information is started.

  In the present invention, the land data written by the laser power test is erased after obtaining the IL characteristics and asymmetry.

  In the present invention, when it is desired to acquire the laser characteristics of the laser diode, it is not necessary to write to the disk. Detect power. At this time, since the signal reflected from the disk cannot be detected because the focus is lost, the tracking control is set to the hold (fixed) state, and when the actual information recording is started, the target groove position is reached. Reduce seek time.

  Further, in the present invention, when an interruption occurs during recording on the disc, a lossless linking period until the recording is resumed. Write with laser power.

  According to the present invention, in order to acquire laser characteristics in information recording on an optical disc, the test light emission is not performed on the groove portion where information is actually recorded, and data used for recording is recorded. Since test light emission is executed in the land portion having auxiliary information such as address information, stable laser power control is possible even during high-speed recording without reducing the recording capacity of the optical disk as a recording medium.

  At this time, the crosstalk to the adjacent groove area can be reduced by defocusing or defocusing.

  In addition, when the laser power test is performed, focus ON to the substrate surface and tracking hold control are executed, so that the time required for information recording after the test can be shortened.

  In addition, in order to obtain the optimum laser power in optical disc information recording, not only the innermost circumference (PCA area) where test recording is actually performed, but also test recording is performed on land portions of the middle and outer circumferences of the disc on which data is recorded. The optimum power due to sensitivity and film thickness variations in the disk surface is corrected, and high-quality recording can be performed even on a bad disk.

  Further, the crosstalk can be reduced by erasing the data written in the land during the laser power test after the test is completed.

  Further, by performing test light emission in the land portion at the time of loss linking, it is possible to perform high-quality writing and recording.

  Hereinafter, a first embodiment of the present invention will be described.

  FIG. 1 is a structural diagram showing a part on a substrate of an optical disk recording medium according to the present embodiment. In FIG. 1, 11 is a wobbled groove formed spirally or concentrically on the disk, 12 is a land between the wobbles 11, and 13 is a predetermined phase with respect to the wobble signal. Reference numeral 14 is a land pit that has a relationship and represents auxiliary information such as address information for recording data, and 14 is a recording layer in which the light absorptivity or refractive index is changed by a laser beam that outputs a recording laser power. 15 is a reflective layer that reflects the laser light emitted to the optical disc, 16 is a protective layer provided for heat resistance and scratch resistance, and 17 is data written to the groove portion 11 when recording is performed. A data recording pit 18 is a test recording pit indicating test data written during a laser power test. Since the protective layer 16 is mainly required for heat resistance, scratch resistance, adhesion, strength, etc., the protective layer 16 is mainly composed of a high strength resin such as a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin, and the like. It is desirable to use material components in combination.

  FIG. 2 is a configuration diagram of an optical disc apparatus that executes recording control according to the present embodiment. Reference numeral 21 denotes a laser diode that emits laser light to the optical disk, a photo detector that detects the laser light reflected from the optical disk, and an optical pickup having a front light detector that receives the front light of the laser light. A front light laser power detection unit that detects the front light laser power from the front light of the laser light, and 23 is a peak value for detecting the peak value and the bottom value of the front light laser power detected by the front light laser power detection unit 22 A bottom value detection unit 24 includes a value detected by the peak value / bottom value detection unit 23 and a drive current value for driving the laser diode of the pickup 21 when the front light laser power reaches the peak value and the bottom value. Calculates the current and laser power characteristics of a laser diode from the relationship. An acquisition unit 25 is a peak / bottom power drive value calculation unit that calculates a drive current value for outputting desired peak laser power and bottom laser power based on the calculation result of the IL characteristic calculation unit 24. , 26 is an RF signal detector for detecting an RF signal component from a signal generated from the reflected light received by the optical pickup 21, and 27 is an irregularity of the depth of the pit written on the optical disk by the power of the laser beam. An asymmetry calculation unit that calculates asymmetry to be expressed, 28 is an optimum power calculation unit that calculates an optimum laser power based on the characteristics of the optical disk based on the calculation result of the asymmetry calculation unit 27, and 29 is an optimum power calculation unit. The drive current value for the laser diode of the optical pickup 21 to output the optimum laser power based on the calculation result of An optimal peak power drive value calculation unit 30 is calculated. A laser diode 30 controls the current for driving the optical pickup 21 based on the calculation results of the peak / bottom power drive value calculation unit 25 and the optimum peak power drive value calculation unit 29. A driver 31 generates a focus signal and a tracking signal from signals output by the photodetector of the optical pickup 21 detecting and outputting the reflected light from the optical disc, and controls the optical pickup 21 based on these signals to control the focus. A focus / tracking servo unit that executes control and tracking control, 32 is a spindle motor that controls the rotation of the optical disk, and 33 is a wobble of a signal that the photodetector of the optical pickup 21 detects and outputs reflected light from the optical disk. Spindle motor 3 from signal component 2 is a spindle servo section for controlling 2 to an optimum rotational speed.

  Next, a recording method according to the present embodiment using the optical disc recording apparatus having the configuration shown in FIG. 2 for the optical disc having the structure shown in FIG. 1 will be described with reference to the flowchart of FIG.

  Prior to recording data on the optical disc, a test for calculating the optimum laser power for recording is started (S401). First, the laser diode included in the optical pickup 21 is driven to emit laser light (S402). Next, the optical pickup 21 is controlled to move the laser beam spot to the land portion 12 of the optical disk (S403). When the laser beam spot is moved to the land portion 12, the laser diode is controlled by changing the drive current so that the laser beam has an approximate laser power required for recording on the optical disk. Further, based on the front light of the laser light detected by the front light power detection unit 22, the peak value / bottom value detection unit 23 determines that the value of the front light power during the peak laser power output is constant. It detects as power (S404). Next, the IL characteristic calculation unit 24 sets the detected bottom laser power value to y [W], the peak laser power value to Y [W], and the laser when the bottom laser power value is obtained. Assuming that the diode drive current is x [A] and the laser diode drive current at the peak laser power value is X [A], the relationship between the laser diode drive current and the laser power of the laser diode is shown in FIG. Calculate (S405). On the other hand, the laser light emitted from the laser diode of the optical pickup 21 and reflected from the optical disk is received by the photodetector (S406). The received reflected light is converted into a signal, and the RF component is extracted by the RF signal detector 26. Based on the extracted RF component, the asymmetry calculation unit detects the depth of the pit 18 written on the optical disc, and calculates the relationship between the laser power and the characteristics of the optical disc medium (S407). The optimum power calculator 28 calculates a laser power suitable for recording on the optical disc under test based on the relationship calculated by the asymmetry calculator. Through the above steps, the peak / bottom power drive value calculation unit 25 and the optimum peak power drive value calculation unit 29 calculate the drive current suitable for the laser diode to output the optimum laser power, and the laser diode driver 30 Determines the optimum drive current obtained from the calculation results (S408). When the optimum laser power is detected, the pickup 21 is controlled to move the laser beam spot to the groove 11 and start recording (S409, S410).

  Note that the processing procedures of the IL characteristic acquisition step S405 and the asymmetry acquisition step S407 in the flowchart shown in FIG. 4 are not necessarily the same, and the asymmetry acquisition step S407 is executed prior to the IL characteristic acquisition step S405. In the same way, the present embodiment holds, these processes can be executed simultaneously, and either one of the processes may be executed. When only the IL characteristic is acquired, the laser is obtained. Diode characteristics can be obtained, and disk characteristics can be obtained when asymmetry is obtained.

  In carrying out this embodiment, the recording period for the test on the land portion 12 is 11T at the normal speed recording. However, in the case of the double speed recording, the period writing corresponding to the double speed is performed. It is preferable to implement. For example, as shown in FIG. 3, (a) is an example of executing conventional 11T period test writing, but in the case of 16 × speed recording, 11T × 16 176T period test writing is performed as shown in (b). Stable laser characteristics can be obtained by changing to implement the above. Further, the test writing period may be shorter than that as long as the laser characteristics can be stably obtained even in the shorter period. The period during which laser characteristics can be stably obtained can be obtained experimentally.

  With the above operation, it is possible to obtain the optimum laser power and the drive current to the laser diode without performing the recording for the laser power test in the groove portion where the data is actually recorded prior to the recording on the optical disk.

  Next, a second embodiment of the present invention will be described. The present embodiment can be implemented using the optical disc having the structure shown in FIG. 1 and the optical disc apparatus having the configuration shown in FIG. 2 used in the first embodiment.

  In this embodiment, in addition to the operation until the recording laser power for the test recording in the first embodiment is calculated, the focus ON control operation is performed on the disk substrate during the test recording. Hereinafter, the present embodiment will be described with reference to the flowchart shown in FIG.

  Prior to recording data on the optical disc, a test for calculating the optimum laser power for recording is started (S501). First, the laser diode included in the optical pickup 21 is driven to emit laser light (S502). Next, the optical pickup 21 is controlled to move the laser beam spot to the land portion 12 of the optical disk (S503). When the laser beam spot is moved to the land portion 12, the laser diode is controlled by changing the drive current so that the laser beam has an approximate laser power required for recording on the optical disk. Further, based on the front light of the laser light detected by the front light power detection unit 22, the peak value / bottom value detection unit 23 determines that the value of the front light power during the peak laser power output is constant. The power is detected (S504). Next, the IL characteristic calculation unit 24 sets the detected bottom laser power value to y [W], the peak laser power value to Y [W], and the laser when the bottom laser power value is obtained. Assuming that the diode drive current is x [A] and the laser diode drive current at the peak laser power value is X [A], the relationship between the laser diode drive current and the laser power of the laser diode is shown in FIG. Calculate (S505). On the other hand, the laser light emitted from the laser diode of the optical pickup 21 and reflected from the optical disk is received by the photodetector (S506). The received reflected light is converted into a signal, and the RF component is extracted by the RF signal detector 26. Based on the extracted RF component, the asymmetry calculation unit detects the depth of the pits 18 written on the optical disk, and calculates the relationship between the laser power and the characteristics of the optical disk medium (S507). The optimum power calculator 28 calculates a laser power suitable for recording on the optical disc under test based on the relationship calculated by the asymmetry calculator. Further, based on the reflected light received in step S506, the focus / tracking servo unit 31 generates a focus error signal, and controls the optical pickup 21 based on the error signal to execute focus control. Through the above steps, the peak / bottom power drive value calculation unit 25 and the optimum peak power drive value calculation unit 29 calculate the drive current suitable for the laser diode to output the optimum laser power, and the laser diode driver 30 Determines the optimum drive current obtained from the calculation results (S510). When the optimum laser power is detected, the pickup 21 is controlled to move the laser beam spot to the groove 11 and start recording (S511, S512).

  Note that the processing procedures of the IL characteristic acquisition step S505, the asymmetry acquisition step S507, the step S508 for controlling the focus ON state, and the step S509 for controlling the tracking ON state in the flowchart shown in FIG. The present embodiment similarly holds in no particular order, and these processes can be executed simultaneously.

  Further, in carrying out this embodiment as in the first embodiment, the recording period for the test on the land portion 12 is sufficient at 11T during normal speed recording, but in the case of double speed recording, It is preferable to perform writing for a period corresponding to the double speed. For example, as shown in FIG. 3, (a) is an example of executing conventional 11T period test writing, but in the case of 16 × speed recording, 11T × 16 176T period test writing is performed as shown in (b). Stable laser characteristics can be obtained by changing to implement the above. Further, the test writing period may be shorter than that as long as the laser characteristics can be stably obtained even in the shorter period. The period during which laser characteristics can be stably obtained can be obtained experimentally.

  Also, by performing focus control during the laser power test, it is possible to enter focus control immediately after shifting to data recording after the test is completed, and by performing tracking control during the laser power test. , Since the transition to the data recording in the groove section near the end of the test can be performed immediately, even if only one of the focus control and tracking control at the time of the laser power test is performed, there is an excellent effect, Naturally, by performing both controls, a further excellent effect can be obtained.

  Next, a third embodiment of the present invention will be described. The present embodiment can be implemented using the optical disc having the structure shown in FIG. 1 and the optical disc apparatus having the configuration shown in FIG. 2 used in the first embodiment.

  In this embodiment, in the operation up to the calculation of the recording laser power by the test recording in the first embodiment, the focus is removed or defocused, and the reflected light from the optical disk is received. Thus, the operation of detecting asymmetry is omitted. Hereinafter, the present embodiment will be described with reference to the flowchart shown in FIG.

    Prior to recording data on the optical disc, a test for calculating the optimum laser power for recording is started (S601). First, the laser diode included in the optical pickup 21 is driven to emit laser light (S602). Next, the optical pickup 21 is controlled to move the laser beam spot to the land portion 12 of the optical disk (S603). Here, the optical pickup 21 is controlled so that the spot of the laser beam is not focused on the optical disc, and the defocused state or the out-of-focus state is set (S604). When the laser beam spot is moved to the land portion 12, the laser diode is controlled by changing the drive current so that the laser beam has an approximate laser power required for recording on the optical disk. Further, based on the front light of the laser light detected by the front light power detection unit 22, the peak value / bottom value detection unit 23 bottoms the power of the front light of the laser light in any laser power output before recording. The laser power is detected, and the value at which the power of the front light during the peak laser power output is constant is detected as the peak laser power (S605). Next, the IL characteristic calculation unit 24 sets the detected bottom laser power value to y [W], the peak laser power value to Y [W], and the laser when the bottom laser power value is obtained. Assuming that the diode drive current is x [A] and the laser diode drive current at the peak laser power value is X [A], the relationship between the laser diode drive current and the laser power of the laser diode is shown in FIG. Calculate (S606). Based on the result, the peak / bottom power drive value calculation unit 25 calculates a drive current suitable for the laser diode to output the optimum laser power, and the laser diode driver 30 is obtained from the calculation result. The optimum drive current is determined (S607). When the optimum laser power is detected, the pickup 21 is controlled to move the laser beam spot to the groove portion 11 and start recording (S608, S609).

  As in the first embodiment, when the present embodiment is implemented, the test recording period on the land portion 12 is 11T when recording at normal speed, but when recording at double speed, It is preferable to perform writing for a period corresponding to the double speed. For example, as shown in FIG. 3, (a) is an example of executing conventional 11T period test writing, but in the case of 16 × speed recording, 11T × 16 176T period test writing is performed as shown in (b). Stable laser characteristics can be obtained by changing to implement the above. Further, the test writing period may be shorter than that as long as the laser characteristics can be stably obtained even in the shorter period. The period during which laser characteristics can be stably obtained can be obtained experimentally.

  As described above, according to the present embodiment, when it is desired to obtain the laser characteristics of the laser diode, the laser light is emitted by removing the focus on the optical disk. An optimum driving current for driving can be obtained.

  Next, a fourth embodiment of the present invention will be described. The present embodiment can be implemented using the optical disc having the structure shown in FIG. 1 and the optical disc apparatus having the configuration shown in FIG. 2 used in the first embodiment.

  In this embodiment, in addition to the operation up to calculating the recording laser power by the test recording in the first embodiment, after calculating the optimum recording laser power, the mark written in the test recording is erased. The operation is performed. Hereinafter, the present embodiment will be described with reference to the flowchart shown in FIG.

  Prior to recording data on the optical disc, a test for calculating the optimum laser power for recording is started (S701). First, the laser diode included in the optical pickup 21 is driven to emit laser light (S702). Next, the optical pickup 21 is controlled to move the laser light spot to the land portion 12 of the optical disk (S703). When the laser beam spot is moved to the land portion 12, the laser diode is controlled by changing the drive current so that the laser beam has an approximate laser power required for recording on the optical disk. Further, based on the front light of the laser light detected by the front light power detection unit 22, the peak value / bottom value detection unit 23 bottoms the power of the front light of the laser light in any laser power output before recording. The laser power is detected, and the value at which the power of the front light during the peak laser power output is constant is detected as the peak laser power (S704). Next, the IL characteristic calculation unit 24 sets the detected bottom laser power value to y [W], the peak laser power value to Y [W], and the laser when the bottom laser power value is obtained. Assuming that the diode drive current is x [A] and the laser diode drive current at the peak laser power value is X [A], the relationship between the laser diode drive current and the laser power of the laser diode is shown in FIG. Calculate (S705). On the other hand, the laser beam emitted from the laser diode of the optical pickup 21 and reflected from the optical disk is received by the photodetector (S706). The received reflected light is converted into a signal, and the RF component is extracted by the RF signal detector 26. Based on the extracted RF component, the asymmetry calculation unit detects the depth of the mark 18 written on the optical disk and calculates the relationship between the laser power and the characteristics of the optical disk medium (S707). The optimum power calculator 28 calculates a laser power suitable for recording on the optical disc under test based on the relationship calculated by the asymmetry calculator. Through the above steps, the peak / bottom power drive value calculation unit 25 and the optimum peak power drive value calculation unit 29 calculate the drive current suitable for the laser diode to output the optimum laser power, and the laser diode driver 30 Determines the optimum drive current obtained from the calculation results (S708). When the optimum driving current is obtained, the recorded pits are erased for the laser power test (S709). Then, the pickup 21 is controlled to move the laser beam spot to the groove portion 11 to start recording (S710, S711).

  As in the first embodiment, the processing procedure of the IL characteristic acquisition step S705 and the asymmetry acquisition step S707 in the flowchart shown in FIG. 7 is not necessarily the same. Even if the acquisition step S707 is executed before the IL characteristic acquisition step S705, the present embodiment is similarly established, and these processes can be executed at the same time, and either one of the steps is executed. The laser diode characteristics can be obtained when only the IL characteristic is obtained, and the disk characteristics can be obtained when the asymmetry is obtained.

  Further, since the test recording can be performed at an arbitrary land portion of the disc, the characteristics of the disc of each track can be obtained, and the optimum power value for each track can be determined.

  Further, in carrying out this embodiment as in the first embodiment, the recording period for the test on the land portion 12 is sufficient at 11T during normal speed recording, but in the case of double speed recording, It is preferable to perform writing for a period corresponding to the double speed. For example, as shown in FIG. 3, (a) is an example of executing conventional 11T period test writing, but in the case of 16 × speed recording, 11T × 16 176T period test writing is performed as shown in (b). Stable laser characteristics can be obtained by changing to implement the above. Further, the test writing period may be shorter than that as long as the laser characteristics can be stably obtained even in the shorter period. The period during which laser characteristics can be stably obtained can be obtained experimentally.

    With the above operation, it is possible to obtain the optimum laser power and the drive current to the laser diode without performing the recording for the laser power test in the groove portion where data is actually recorded prior to the recording on the optical disc. Since the pits in the land portion recorded for the laser power test are erased, the crosstalk to the groove portion can be reduced.

  Next, a fifth embodiment of the present invention will be described. The present embodiment can be implemented using the optical disc having the structure shown in FIG. 1 and the optical disc apparatus having the configuration shown in FIG. 2 used in the first embodiment.

  In the present embodiment, when recording is interrupted during data recording on the optical disc, the same power is maintained in the land portion near the recording interruption position during the loss linking period from the recording interruption position to the start of recording again. The laser emission is continued. It is also possible to maintain the focus control and tracking control in the ON state during the loss linking period. As a factor that interrupts data recording, there is a case where the supply of data to be recorded is not in time for the recording speed. Hereinafter, the present embodiment will be described with reference to the flowchart shown in FIG.

  First, during data recording on the optical disc, the recording operation is temporarily interrupted for the reason that the supply of data is not in time as described above (S801). In that case, the optical pickup 21 is controlled to move the spot of the laser beam emitted from the laser diode to the land portion 12 in the vicinity of the groove portion 11 to which the position where the recording is interrupted belongs (S802). The land portion in the vicinity of the groove portion may be a land portion adjacent to the groove portion. Even if the spot of the laser beam of the laser diode moves to the land portion 12, the laser diode is continuously driven so that the laser power is kept the same as when recording on the groove portion 11. At this time, the focus control is turned on on the surface of the disk substrate (S803). Also, the tracking control is set to the hold state (S804). When recording on the disc becomes possible again, the optical pickup 21 is controlled to move the laser light spot emitted from the laser diode to the groove portion 11 to which the recording interrupted position belongs (S805). Then, the linking address indicating the position where the recording is interrupted is detected, and the recording is resumed immediately after the recording interruption position (S806, S807).

  According to the present embodiment, since the same laser power can be maintained during the lossless linking period from when the recording to the disk is interrupted until the recording is started again, it is possible to perform high-quality connected recording. Also, if the focus is controlled to be ON during this lossless linking period, the focus control can be quickly started when recording is resumed, and the recording layer of the disc is not in focus. Reduce the impact. Further, by holding the tracking during the lossless linking period, it is possible to quickly execute a jump to the groove portion to which the position where the recording is interrupted when the recording is resumed. In addition, the description has been given of the mode in which the recording is performed while the focus and tracking are maintained in the ON state. Play.

  Next, a sixth embodiment of the present invention will be described. The present embodiment can be implemented using the optical disc having the structure shown in FIG. 1 and the optical disc apparatus having the configuration shown in FIG. 2 used in the first embodiment.

  In the present embodiment, in addition to the operation of continuing the laser emission in the nearby land between the recording interruption and the recording resumption in the fifth embodiment, the IL characteristic of the laser diode between the recording interruption and the recording resumption. Test light emission for obtaining the above is performed. Hereinafter, the present embodiment will be described with reference to the flowchart shown in FIG.

  First, during the data recording on the optical disc, the recording operation is temporarily interrupted for the reason that the supply of data is not in time as described above (S901). In that case, the optical pickup 21 is controlled to move the laser light spot emitted from the laser diode to the land portion 12 in the vicinity of the groove portion 11 to which the position where the recording is interrupted belongs (S902). The land portion in the vicinity of the groove portion may be a land portion adjacent to the groove portion. First, focus control is turned on on the surface of the disk substrate (S903). Also, the tracking control is set to the hold state (S904). Next, in order to newly acquire the laser characteristics of the laser diode, the driving current is changed, and the front light receiving element receives the front light of the laser light output from the laser diode whose driving current is changing (S905). ). The front light power detection unit 22 detects the power of the front light of the laser beam, and the peak value / bottom value detection unit 23 sets the value at which the front light power during the peak laser power output is constant to the peak laser. Detect as power. Next, the IL characteristic calculation unit 24 sets the detected bottom laser power value to y [W], the peak laser power value to Y [W], and the laser when the bottom laser power value is obtained. Assuming that the diode drive current is x [A] and the laser diode drive current at the peak laser power value is X [A], the relationship between the laser diode drive current and the laser power of the laser diode is shown in FIG. Calculate (S906). When recording on the disc becomes possible again, the optical pickup 21 is controlled to move the laser light spot emitted by the laser diode to the groove portion 11 to which the recording interrupted position belongs (S907). Then, the linking address indicating the position where the recording is interrupted is detected, and the laser diode driver 30 supplies the driving current for recording based on the laser characteristic of the laser diode newly obtained in the IL characteristic acquisition step S904. Recording is resumed immediately after the recording interruption position (S908, S909).

  According to the present embodiment, since the laser characteristics of the laser diode are newly acquired during the lossless linking period from when the recording to the disk is interrupted until the recording is started again, the latest information on the laser characteristics that change due to temperature changes, etc. Can be obtained. Also, if the focus is controlled to be ON during this lossless linking period, the focus control can be quickly started when recording is resumed, and the recording layer of the disc is not in focus. Reduce the impact. Further, by holding the tracking during the lossless linking period, it is possible to quickly execute a jump to the groove portion to which the position where the recording is interrupted when the recording is resumed. In addition, the description has been given of the mode in which the recording is performed while the focus and tracking are maintained in the ON state. Play.

  As described above, in each embodiment, the present invention has been described using the optical disk apparatus having the configuration shown in FIG. 2, but the hardware configuration necessary for carrying out the present invention is not necessarily limited to this configuration. Any configuration that is necessary for realizing the above functions may be used.

  INDUSTRIAL APPLICABILITY The present invention is useful in control that requires obtaining the characteristics of a laser diode or the characteristics of a disk in an optical disk device that supports high speed.

Structure diagram of optical disc according to the present invention Configuration diagram of optical disc apparatus according to the present invention Diagram showing change of test recording period corresponding to high-speed recording The flowchart which concerns on 1st embodiment of this invention The flowchart which concerns on 2nd embodiment of this invention The flowchart which concerns on 3rd embodiment of this invention Flowchart according to the fourth embodiment of the present invention Flowchart according to the fifth embodiment of the present invention Flowchart according to the sixth embodiment of the present invention Surface view of recordable optical disc Data structure diagram of recordable optical disc Structure of conventional optical disc Laser diode IL characteristics calculation chart Calculation diagram of asymmetry

Claims (14)

A method of calculating a drive current for outputting an optimum power of a laser beam used for recording on an optical disk recording medium having a groove part and a land part,
A step of moving a spot of laser light output from a laser diode to a land portion of the optical disc;
Changing the current for driving the laser diode for an arbitrary test period to change the power of the laser light output from the laser diode; and
Detecting the peak power and bottom power of the front light of the laser light received by the front light receiving element during the test period;
Characteristics of the laser diode based on the peak power and the bottom power, and the driving current value of the laser diode that makes the front light the peak power and the driving current value of the laser diode that makes the front light the bottom power The process of detecting
An optical disk recording control method, wherein a driving current value for the laser diode to output an optimum laser power is obtained. A method for calculating an optimum power of laser light used for recording on an optical disk recording medium having a groove portion and a land portion;
A step of moving a spot of laser light output from a laser diode to a land portion of the optical disc;
Calculating the asymmetry of the optical disk based on the laser power of the reflected light from the optical disk of the laser light,
An optical disc recording control method, comprising: obtaining an optimum laser power for recording data on the optical disc. The method further comprises a step of calculating an asymmetry of the optical disk based on a laser power of the reflected light from the optical disk of the laser light, and obtaining an optimum driving current for recording data on the optical disk. 2. The optical disc recording control method according to 1. Generating a tracking error signal from a signal generated based on reflected light from the optical disk of the laser light;
4. The optical disc control method according to claim 1, further comprising a step of performing tracking control based on the tracking error signal. Generating a focus error signal from a signal generated based on reflected light from the optical disk of the laser light;
4. The optical disc control method according to claim 1, further comprising a step of performing focus control based on the focus error signal. 4. The optical disc recording control method according to claim 1, wherein a spot of the laser beam on the optical disc is defocused while the laser beam is output to a land portion of the optical disc. 4. The optical disc recording control method according to claim 1, wherein a spot of the laser beam on the optical disc is defocused while the laser beam is output to a land portion of the optical disc. 6. The method according to claim 1, further comprising a step of erasing data recorded by outputting the laser beam to the land portion after acquiring the characteristics and asymmetry of the laser diode. Optical disk control method. A recording control method for recording on an optical disk recording medium having a groove part and a land part,
When recording on the optical disc becomes impossible and interrupted, the step of moving the spot of the laser beam output from the laser diode to the land portion in the vicinity of the recording interrupted position,
And a step of returning the spot of the laser beam outputted from the laser diode to a position where the recording is interrupted when recording becomes possible again. A recording control method for recording on an optical disk recording medium having a groove part and a land part,
When recording on the optical disc becomes impossible and interrupted, the step of moving the spot of the laser beam output from the laser diode to the land portion in the vicinity of the recording interrupted position,
Changing the current for driving the laser diode for an arbitrary test period to change the power of the laser light output from the laser diode; and
Detecting the peak power and bottom power of the front light of the laser light received by the front light receiving element during the test period;
Characteristics of the laser diode based on the peak power and the bottom power, and the driving current value of the laser diode that makes the front light the peak power and the driving current value of the laser diode that makes the front light the bottom power Detecting the
And a step of returning the spot of the laser beam outputted from the laser diode to a position where the recording is interrupted when recording becomes possible again. Recording is interrupted, and the spot of the laser beam output from the laser diode is moved to the land portion of the optical disc, and then the spot of the laser beam output from the laser diode is returned to the position where the recording is interrupted. 11. The optical disk control method according to claim 10, wherein the focus is turned on for the surface of the base material of the optical disk. Recording is interrupted, and the spot of the laser beam output from the laser diode is moved to the land portion of the optical disc, and then the spot of the laser beam output from the laser diode is returned to the position where the recording is interrupted. 11. The optical disc control method according to claim 10, wherein the tracking control is kept in a hold state during the operation. 2. The optical disc control according to claim 1, wherein an execution period of the step of detecting the peak power and the bottom power of the front light of the laser light received by the front light receiving element is lengthened according to a recording speed. Method. 2. The optical disc control method according to claim 1, wherein the execution period of the step of calculating the asymmetry of the optical disc based on the laser power of the reflected light of the laser beam from the optical disc is lengthened according to the recording speed.

Images