JP2013175248A - Recording power adjusting method, information recording and reproducing device and information recording medium - Google Patents

Abstract

When recording is performed at an unknown speed, recording adjustment is necessary prior to recording, and it takes time to start recording. Therefore, it is difficult to realize high-speed recording with a CAV in which the recording speed continuously changes.
An approximate expression relating a recording speed and an optimum recording power is determined based on a thermal characteristic of a medium, an optimum recording power at a current recording speed is calculated using the approximation expression, and the calculated optimum recording power is used. By performing recording, high-speed recording by CAV is realized without interrupting recording.
[Selection] Figure 15

Description

  The present invention relates to a recording power adjustment method for adjusting recording power, and an information recording / reproducing apparatus for implementing the recording power adjustment method.

  Currently, CD (Compact Disc), DVD (Digital Versatile Disc), BD (Blu-ray Disc), BDXL, and the like have been commercialized as optical discs that are optical information recording media. These optical discs include a read-only type ROM type (Read Only Memory), a write-once type R type (Recordable), and a rewritable type RE type (Rewritable). The data capacity of optical disks has been increased to CD (650 MB), DVD (single layer 4.7 GB), and BD (25 GB). These were realized mainly by shortening the wavelength of the light source and increasing the NA of the objective lens. On the other hand, in BDXL that has been commercialized in recent years, the data layer is multi-layered to 3 to 4 layers based on BD, and the surface density per layer is increased to 32 to 33.4 GB by signal processing. A large capacity of 128 GB was realized. As the capacity increases in the future, it is difficult to shorten the wavelength of the light source and increase the NA of the objective lens, so further multilayering and higher density are being studied.

  Information recording / reproduction on the optical disc is performed by irradiating the optical disc with laser light by an optical disc apparatus which is an optical information recording / reproduction device. Information is reproduced by irradiating the data layer of the optical disc with a low-power laser beam and detecting the difference in the amount of reflected light at each irradiation position. Information is recorded by forming marks with changed optical characteristics in the data layer using a high-power laser beam.

  In the reproduction of information, the mark on the data layer is read as a change in the amount of reflected light, but the SNR (Signal to Noise Ratio) of this reproduction signal changes depending on the reproduction power. In order to increase the SNR and improve the reproduction signal quality, reproduction using a high reproduction power is desirable. However, if the reproduction power is too high, there is a possibility that the recorded signal is deteriorated. Therefore, the optical disk apparatus has a function of adjusting the reproduction power within a range that does not deteriorate the signal according to the reproduction speed.

  For example, Patent Document 1 discloses a reproduction power adjustment method that enables reproduction without always degrading reproduction signal quality even when the reproduction speed is changed. In this method, a laser power setting table for determining the current reproduction power from the ratio between the target reproduction speed and the current reproduction speed is acquired in advance. During playback speed change, playback is performed by determining the current playback power from the laser power setting table using the current playback speed and target playback speed. As a result, even when the playback speed is changed, the playback power is changed in stages, so that good playback is always achieved without deteriorating the recorded signal.

  Further, for example, Patent Document 2 discloses a reproduction power adjustment method when changing the reproduction speed in a super-resolution medium that enables reproduction of a mark having an optical resolution or less. In this method, an optimum reproduction power at two reproduction speeds is determined in advance, and a table of optimum reproduction power at each reproduction speed is created by linearly interpolating the relationship between the reproduction speed and the optimum reproduction power. During playback, the optimum playback power at the current playback speed is determined from the created table, so that good playback is always achieved. This reproduction power adjustment method is used not to improve the SNR of the reproduction signal, but to maintain the state where the super-resolution effect is most obtained by adjusting the temperature of the super-resolution film provided on the medium. It is done.

  In recording information, the optimum recording power differs depending on the type of optical disc and the manufacturer of the optical disc, and the drive needs to set the optimum recording power according to the type of optical disc. However, even with the same type of optical disk, the optimum recording power differs for each optical disk due to manufacturing variations, and optimal recording may not be realized with the same recording power. Even when the same optical disk is used, optimal recording may not be realized with the same set power due to power variations between drives. Therefore, each drive has a configuration in which, prior to recording on the optical disc, trial writing is performed in a predetermined area, and the optimum recording power is adjusted according to the optical disc. The recording power adjustment operation in this recording is called OPC (Optimum Power Control). With this OPC, each optical disk apparatus realizes good information recording.

  Unlike the OPC described above, Patent Document 3 discloses a recording power adjustment method for realizing CAV (Constant Angular Velocity) recording. In this method, CAV recording is realized by dividing the recording area along the radial direction of the disc and changing the recording conditions for each area. Here, the recording power in each area is proportional to the recording speed, and correction is performed based on the quality of the recording signal in each area. The recording waveform is also corrected according to the recording speed.

JP 2001-38354 A JP 2005-135538 A Japanese Patent Laid-Open No. 2001-3409

  However, depending on the thermal characteristics of the medium, CAV recording may not be realized even using the recording power adjustment method disclosed in Patent Document 3. For example, it is assumed that CAV recording is performed using the recording waveform of FIG. 1A. The recording waveform in FIG. 1A is called a multi-pulse, and marks are formed by pulse irradiation. There are a plurality of recording powers used for multi-pulses, which are indexed as Pw, Ps, Pc, Pb (or Pb, Pc) from the highest. At each linear velocity, the channel bit length 1T of the recording waveform was increased or decreased in proportion to the linear velocity, the Pw / Ps ratio was constant, and Pc and Pb were fixed values. The result of determining the optimum recording power at each linear velocity is shown in FIG. In the medium used for the measurement in FIG. 2, it can be seen that the relationship between the recording speed and the optimum recording power Pw is a curve and cannot be linearly approximated. The result of FIG. 2 does not depend on the recording waveform used, and the same applies when the monopulse, L-type, and castle-type recording waveforms of FIG. 1B are used. These waveforms are a system in which recording power is formed by irradiating a medium with constant power (except for the front and rear edges) to form a recording mark, and the recording power to be used is Pw, Pm, Ps and Pc are indexed. In particular, a waveform with no trailing edge pulse is called L-type, and a waveform with no pulses at both front and rear edges (without Pm) is called a monopulse.

  FIG. 3 shows the result of recording performed on this medium by determining the recording power at other recording speeds by linearly approximating the optimum recording powers of 2x and 6x or 2x and 12x. The horizontal axis in FIG. 3 is the recording speed, and the vertical axis is the bER (bit error rate). FIG. 3 also shows the case of recording with the optimum recording power. When the recording power is calculated by linear approximation, it can be seen that the recording power at an unknown linear velocity cannot be calculated correctly, and as a result, the signal quality is deteriorated. Accordingly, since the relationship between the recording speed and the optimum recording power varies depending on the thermal characteristics of the medium, the optimum recording power cannot be determined by linear approximation and CAV recording may not be realized.

  In order to compensate for the deviation of the calculated recording power, Patent Document 3 discloses a method of detecting excess or deficiency in recording power by reproducing a recording signal after recording each recording area. Although CAV recording is realized by such a method, since a constant recording waveform and recording power are used in each region, variations in signal quality always remain in the region. Also, since the recorded signal is reproduced and the recording power is compensated, CAV recording is interrupted at any time, and high-speed recording cannot be realized. Therefore, in the conventional CAV recording method, depending on the thermal characteristics of the medium, it may be difficult to realize high-speed recording and good signal quality.

  The present invention solves the above-described problems and provides a recording power adjustment method for providing the best CAV recording method for each medium, an information recording medium and information recording / reproducing apparatus for holding information used for recording power adjustment, and the recording power adjustment. An information recording / reproducing apparatus for performing the method is provided.

  The above problem is to determine an approximate expression of the relationship between the recording speed and the optimum recording power based on the thermal characteristics of the medium, determine the recording power at each recording speed using the determined approximate expression, and use the determined recording power. This can be solved by using the recording power adjustment method of the present invention that performs CAV recording.

The following equations (1) to (4) are used as approximate equations.

Here, P is the recording power, v is the recording speed, P1 is the reference recording power, v1 is the reference recording speed, and n, α ₁ , α ₂ , and α ₃ are constants.

  In the recording power adjustment, the recording speed is substituted into the approximate expressions (1) to (4) in which the parameters are determined, the recording power is calculated, and recording is performed with the calculated recording power. Accordingly, since the recording power corresponding to each linear velocity can be determined and changed continuously based on the thermal characteristics of each medium, optimum recording with CAV is realized.

  By storing the determined parameters of the approximate expression in the management area of the optical disc or the storage unit of the optical disc apparatus, trial writing for CAV recording becomes unnecessary, and CAV recording can be started quickly.

  According to the recording power adjustment method of the present invention, CAV recording that provides high-speed recording and good recording signal quality can be realized by recording power adjustment based on the thermal characteristics of each medium.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

The figure of an example which shows the recording waveform used for CAV recording. The figure of an example which shows the recording waveform used for CAV recording. The figure of an example which shows the recording power determined by linear interpolation from recording speed, optimal recording power, and two optimal recording powers. The figure of an example which shows the measurement result of the error rate of the signal which recorded using the recording power determined by the optimal recording power and the linear interpolation in each recording speed. 1 is a block diagram showing an example of an optical disc apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating an example of a control unit of an optical disc apparatus according to an embodiment of the present invention. 7 is a flowchart illustrating an example of a recording power adjustment procedure. The figure of an example showing the relationship between the recording power and the error rate at each recording speed. The figure of an example showing the relationship between the recording speed and error rate in each recording waveform. The figure of an example showing the relationship between a recording speed and an error rate when the power level of Pw or Pw and Ps or Pw, Ps, and Pb is adjusted. An example of the relationship between recording speed and optimum recording power. The figure of an example showing the relationship between recording speed ratio and optimal recording power ratio. The figure of an example showing the change with respect to the recording speed of parameter (eta) (v) regarding the thermal characteristic of a medium. The figure of an example which shows the medium temperature distribution of the track direction at the time of recording. An example of the relationship between the logarithm of recording speed and the logarithm of optimum recording power. The figure of an example showing the relationship between the recording power calculated by recording power adjustment, and the optimal recording power. The figure of an example showing the relationship between a recording speed and an error rate at the time of recording using the recording power determined by recording power adjustment. The figure of an example showing the relationship between a recording radius position and an error rate at the time of performing CAV recording using the recording power adjustment of this invention. The schematic diagram of an example which shows the management structure of an optical disk, and the information structure in management information. An example of the relationship between the logarithm of the recording speed ratio and the logarithm of the optimum recording power ratio. The figure of an example showing the relationship between a recording speed and an error rate when changing the recording power which changes according to recording speed in each recording waveform, using a multi-pulse, a monopulse, L type, and a castle type for a recording waveform. FIG. 5 is an example showing a relationship between a radial position and an error rate when CAV recording is performed using equations (1) to (4) as an approximate expression of a relationship between a recording speed and an optimum recording power in recording power adjustment.

  A recording power adjusting method as an embodiment of the present invention will be described with reference to the drawings. In the following, after explaining the configuration of the optical disk apparatus, a recording power adjustment method in the optical disk apparatus will be described as an embodiment of the present invention.

[Example 1]
FIG. 4 shows a block diagram of the main part of the optical disk apparatus used in this embodiment. The optical disk 10 is rotated by a spindle motor 12 and is controlled by CLV (Constant Linear Velocity) or CAV (Constant Angular Velocity). An optical pickup unit 14 is provided opposite to the optical disk 10, and recording / reproduction of the optical disk 10 is performed by irradiating a laser beam 16 from a laser diode (LD).

  When recording a signal, the optical disk 10 is irradiated with a laser beam 16 having a recording power, and the signal is written. When the optical disk 10 is a rewritable optical disk, the signal is erased by irradiating the optical disk 10 with a laser beam 16 having an erasing power. The recording signal is encoded by the encoder 18 and supplied to the LD driving unit 20. The LD drive unit 20 generates a drive signal based on the encoded recording signal, supplies the drive signal to the LD of the optical pickup unit 14, and records the signal by intensity modulation of the laser light 16 based on the supplied signal. The recording power in the LD driving unit 20 is determined by a control signal from the control unit 22. The controller 22 determines the optimum recording power based on the signal quality of trial writing performed in the trial writing area of the optical disc 10 prior to signal recording (OPC: Optimum Power Control).

  When reproducing a signal, the optical disk 10 is irradiated with a laser beam 16 having a reproduction power, and the signal is reproduced. The laser beam 16 reflected by the optical disk 10 is converted into an electric signal by the photodetector of the optical pickup unit 14, and is output as an RF signal or the like after a predetermined calculation. A signal from the optical pickup unit is supplied to an RF signal processing unit (and level acquisition unit) 24. The RF signal processing unit 24 has functions such as an RF amplifier, an equalizer, a binarizer, and a PLL. The RF signal processing unit 24 processes the RF signal with these functions and supplies the processed signal to the decoder 26. The decoder 26 decodes the signal based on the binarized RF signal and the synchronous clock reproduced by the PLL, and outputs it as reproduced data. The RF processing unit 24 also has a level detector, calculates an upper envelope (High envelope), a lower envelope (Low envelope), and the like of the reproduction signal, and supplies them to the controller 22 as a signal evaluation signal. Further, an RF signal is supplied from the RF signal processing unit 24 to the control unit 22 as a signal evaluation signal. A circuit that generates a focus error signal and a tracking error signal at the time of recording / reproduction and controls focus servo and tracking servo, and a circuit that reproduces a wobble signal formed on the optical disc 10 to control address demodulation or rotation of the optical disc 10 However, since these are the same as those of the prior art, description thereof is omitted.

  The control unit 22 has a function of performing reproduction power adjustment and recording power adjustment based on signals supplied from the level calculation unit and the RF signal processing unit 24 and supplying a power control signal as an adjustment result to the LD drive unit 20. . FIG. 5 shows a block diagram of functions related to recording power adjustment and reproduction power adjustment in the control unit 22. The control unit 22 is specifically composed of a microcomputer, and as its functional blocks, a signal quality calculation unit, optimum recording power (Pw) determination unit, power adjustment method determination unit, power adjustment parameter calculation unit, power calculation unit, storage Has a part. The storage unit can be composed of a RAM, and the other functional blocks can be composed of a single CPU.

  The optimum recording power for OPC is determined by the control unit 22. A test writing signal recorded using a plurality of types of recording power is reproduced, a modulation level at each recording power is calculated by the signal quality calculation unit, and the modulation level and the recording power are associated and stored in the storage unit. The optimum recording power determination unit determines the optimum recording power based on the relationship between the recording power and the modulation degree in the storage unit and the management information of the optical disk acquired through a path (not shown). The determined optimum recording power is supplied to the LD driving unit 20 as a power control signal and used for recording.

  The control unit 22 also adjusts the recording power during CAV recording. Using the approximate expression of the recording speed and the optimum recording power acquired in advance in the storage unit, the optimum recording power is calculated based on the current recording speed and supplied to the LD drive unit 20 as a power control signal. The approximate expression of the storage unit may be held in advance by the optical disc apparatus or may be acquired from the management area of the optical disc medium. In addition, prior to CAV recording, the control unit 22 may determine an approximate expression of recording speed and optimum recording power. In that case, trial writing is performed at each recording speed, and a recording power adjusting method that gives a good signal quality at the recording speed to be used and an approximate expression of the recording speed and the optimum recording power are determined based on the result of the trial writing, and the optical disc apparatus Is stored in the storage unit. Further, the determined recording power adjustment method and approximate expression may be stored in the management area of the optical disk medium.

  Here, the power adjustment method refers to a basic recording waveform, a recording waveform control method according to the linear velocity, and a power level changed according to the linear velocity. Signal quality includes bER (bit error rate), SER (symbol error rate), Jitter, i-MLSE (integrated-Maximum Likelihood Sequence Error), and L-SEAT (run-). length-Limited Sequence Error for Adaptive Target) is used. The power adjustment method determination unit determines a power adjustment method used for recording power adjustment based on the signal quality of each linear velocity. The power adjustment parameter calculation unit calculates an approximate expression parameter of this relationship from the relationship between the recording speed and the recording power in the determined power adjustment method and stores it in the storage unit.

  In the following, the result of adjusting the recording power according to the flow of FIG. 6 in CAV recording using the optical disc apparatus will be described. First, trial writing was performed on the trial writing area or the user data area of the optical disc, and the optimum recording power at each recording speed was calculated (S10). As a recording condition, the multipulse shown in FIG. 1A was used for the recording waveform in this example. The channel bit length 1T of the recording waveform was increased or decreased in proportion to the recording speed. In addition, the values of the recording powers Pb and Pc and the ratio of Pw and Ps were constant regardless of the recording speed. FIG. 7 shows the results of measuring the relationship between the recording power and the error rate (bER: bit Error Rate) at each linear velocity. Here, as described above, there are bER, SER, Jitter, i-MLSE, L-SEAT, and the like as signal quality indexes. However, since any index is highly correlated with bER, any index is used. Similar results are obtained.

  The recording power giving the lowest bER at each recording speed in FIG. 7 was determined as the optimum recording power. The result of plotting bER at the optimum recording power at each recording speed is shown in WS1 of FIG. In order to determine the recording waveform in the recording power adjustment and its adjustment method, FIG. 8 shows a case where the power adjustment method is changed and a recording waveform in which the multipulse is increased by 1 / 16T is used (WS2), and in FIG. A measurement result in the case of using a castle type recording waveform (WS3) is also shown. The adjustment of the channel bit length corresponding to each recording speed is the same as that of WS1, and the adjustment method of the recording power Pw, Ps, Pb, Pc of WS2 is also the same as that of WS1. Regarding the recording power of WS3, the ratio of Pw, Pm, and Ps was constant, and Pc was a fixed value. Since the recording waveform and the adjustment method for obtaining good recording signal quality at each recording speed are WS1, the recording waveform of WS1 and the adjustment method are used for recording power adjustment in this embodiment.

  In order to determine the power level to be adjusted in the recording power adjustment, for WS1, each recording speed when the power level to be adjusted is Pw only, Pw and Ps (fixed ratio), and Pw, Ps and Pb (fixed ratio). FIG. 9 shows the result of measuring the relationship between the recording signal quality and the recording signal quality. From this, it can be seen that when only Pw is adjusted, the recording speed is not properly adjusted, and the recording signal quality deteriorates. On the other hand, when at least Pw and Ps are adjusted, it can be seen that the recording speed can be adjusted appropriately. Therefore, in the recording power adjustment of this embodiment, the ratio of Pw and Ps is made constant and these are adjusted. The determination of the power adjustment method in the recording power adjustment described above is performed by the power adjustment method determination unit in FIG.

  FIG. 10 shows the relationship between the recording speed and the optimum recording power in the determined power adjustment method. FIG. 11 shows the result of normalizing the recording speed by 2x and normalizing the recording power by the optimum recording power at 2x. Based on FIG. 10 or FIG. 11, the parameter of the approximate expression is determined in the subsequent step S11 of FIG.

  First, a method for deriving an approximate expression based on the relationship between recording speed and recording power will be described. When the laser beam with power P is irradiated at the recording speed v, the temperature rise ΔT of the medium is approximated by the equation (5).

Here, β ₁ and β ₂ are constants, and Δt is a time during which the laser is irradiated per unit length, which is proportional to 1 / v. Further, η (v) is a coefficient relating to the thermal diffusion characteristics of the medium. FIG. 12 shows the result of calculation with respect to the thermal characteristics of the medium and the linear velocity v. Since η (v) is a function having a steep rise, it can be understood that an actual medium excluding the limit of heat insulation and heat dissipation can be approximated using a power function. In other words, it is approximated by Equation (6).

Here, β ₃ is a constant. Substituting equation (6) into equation (5) and setting the arranged coefficient to β ₄ yields equation (7).

It can be seen that the peak temperature of the medium during recording is approximated to the sum of the temperature rise ΔT and the room temperature Trt, and the recording mark is formed based on this peak temperature and the temperature distribution during recording. Here, the result of simulating the temperature distribution of the medium by the irradiation laser is shown in FIG. In the figure, the cases of 2x and 12x are shown, and an example in which 8T marks are recorded by multi-pulses. The temperature distribution at each speed is normalized using the peak temperature. From this, it can be seen that the temperature distribution normalized by the peak temperature can be regarded as almost constant regardless of the recording speed. Accordingly, it can be seen that the peak temperature needs to be constant in order to form marks of the same size at each recording speed. That is, the recording power and the recording speed need to be controlled so that the equation (7) using the constants ΔT and β ₄ always holds.

Here, Equation (7) is obtained by modifying Equation (7) and summing the constants to α ₁ . Further, in the equation (7), the general form in which the optimum recording power is (P + constant) in consideration of the recording power offset is the equation (2). Therefore, it can be seen that equations (1) and (2) are approximate equations representing the relationship between recording speed and optimum recording power.

  Further, the result of taking the ratio of the optimum recording powers P1 and P at the two recording velocities v1 and v is Equation (3). Equation (4) is an equation that expands Equation (3) to a general form and adds a constant term offset. From this, it can be seen that equations (3) and (4) are approximate equations representing the relationship between the recording speed ratio and the optimum recording power ratio.

From the above theoretical analysis, the relationship between the recording speed and the optimum recording power, and the relationship between the recording speed ratio and the optimum recording power ratio are approximated using Equations (1) to (4). It can be seen that can be determined. Here, the parameters in the approximate expressions (1) and (2) may be calculated by fitting the relationship shown in FIG. Further, the parameters in the approximate expressions of the expressions (3) and (4) may be calculated by fitting the relationship shown in FIG. The fitting method using equations (1) to (4) is performed so that the relationship between the recording speed and the optimum recording power, the relationship between the recording speed ratio and the optimum recording power ratio, and the sum of squares of the errors in the approximate expression are minimized. There is a way. Here, with respect to formula (1), taking the logarithm of both sides, the logarithm of the logarithm and the recording speed of the recording power becomes proportional, the slope of the approximate line is the order n, y intercept corresponds to the coefficient alpha ₁ of the log . Further, regarding the expression (3), when the logarithm of both sides is taken, the logarithm of the recording power ratio and the logarithm of the recording speed ratio are in a proportional relationship, and the slope of the approximate line corresponds to the order n. Therefore, when Equations (1) and (3) are used as approximation equations, a simple fitting method using linear approximation can be used.

In this embodiment, the expression (1) is used as an approximate expression. FIG. 14 shows the result of linear approximation of the logarithm of the recording speed and the logarithm of the optimum recording power in FIG. As a result, n in Equation (1) was determined to be 0.5, and the logarithm of α ₁ was determined to be 0.63. FIG. 15 shows the result of plotting the recording power Pw calculated by substituting the recording speed into the equation (1) in which the parameters are determined. In the figure, the optimum recording power obtained at each recording speed is also shown, and it can be confirmed that the recording power calculated from the equation (1) matches with the optimum recording power. FIG. 16 shows recording signal quality when recording is performed at each recording speed using the calculated recording power. From this, it was confirmed that optimum recording could be realized at each recording speed by using this recording power adjustment.

  Since the calculation of the parameter of the approximate expression in step S11 in FIG. 6 has been completed, CAV recording for adjusting the recording power based on the approximate expression is started (S12). Recording power adjustment was performed by calculating the current recording power by substituting the current recording speed into equation (1) for which parameters were determined. In this method, since the recording power can be continuously changed, it is not necessary to divide the area to which the recording power is applied even in CAV recording. FIG. 17 shows the result of performing CAV recording on the entire surface of the disk using this recording power adjustment method. The recording signal quality was good at all radii, and it was confirmed that high-speed recording and CAV recording giving good signal quality were realized by this recording power adjustment.

  In this embodiment, the power adjustment method and the parameters of the approximate expression are determined in steps S10 and S11 in FIG. 6, but by storing these in the storage unit in FIG. 5, steps S10 and S11 are performed in the next recording. It can be omitted. Further, by storing these parameters in advance in DI (Disc Information) 102 in the management area 101 of the optical disc 100 shown in FIG. 18, steps S10 and S11 shown in FIG. 6 can be omitted in the subsequent recording. It is possible to shorten the time until the recording start S12. For this purpose, the disk manufacturer determines in advance the power adjustment method, approximate expression parameters, reference recording speed and reference optimum recording power by means similar to S10 and S11 in FIG. It is desirable to memorize. In addition, when these parameters are determined by the optical disk device, they can be stored in the management area 101 or stored in the storage unit of the optical disk device so that they can be read out and used when necessary. Recording power adjustment can be performed in a short time.

  In this embodiment, the recording power Pw is controlled with a constant ratio of Pw and Ps. However, it is known from FIG. 9 that an optimum recording signal quality can be obtained even when the ratio of Pw, Ps, and Pb is constant. Therefore, the recording power controlled by the recording power adjustment may be Pw, Ps, Pb. Thus, the recording power to be controlled may be arbitrarily determined based on the characteristics of the medium.

[Example 2]
In this embodiment, the result of adjusting the recording power of CAV recording using equation (3) as an approximate expression will be described. The parts that are not changed are the same as those in the first embodiment and the other embodiments related to the first embodiment, and thus detailed description thereof is omitted here.

  FIG. 19 shows the result of linear approximation of the logarithm of the recording speed ratio and the logarithm of the optimum recording power ratio in FIG. As a result, n in the formula (3) was determined to be 0.5. The reference recording speed v1 in equation (3) is 2x, and the 2x recording power P1 is 6 mW. The result of plotting the recording power Pw calculated by substituting the recording speed into the expression (3) is the same as that in FIG. 15, and the calculated recording power coincides with the optimum recording power.

  As a result of performing CAV recording using this recording power adjustment method, the same results as in FIG. 17 are obtained. By using this recording power adjustment method, CAV recording that provides high-speed recording and good signal quality can be realized. confirmed.

[Example 3]
In the present embodiment, the result of adjusting the recording power of CAV recording using equation (2) as an approximate expression will be described. The parts that are not changed are the same as those in the first embodiment and the other embodiments related to the first embodiment, and thus detailed description thereof is omitted here.

The relationship between the recording speed and the optimum recording power in FIG. 10 was fitted by equation (2) to determine the parameters of equation (2). In the fitting, each parameter was adjusted so that the sum of the square error of the data and equation (2) was minimized. Specifically, the measured recording speed and the optimum recording power are (vi, Pi) (i = 1, 2, 3...; Measurement point index), and the optimum calculated from the approximate expression at each recording speed vi. The square of the difference between the recording power α ₁ × vi ⁿ + α ₂ and Pi is calculated, and the parameters α ₁ , n, α ₂ of the approximate expression are determined so that the sum of the squares of the differences of all points is minimized. . As a result, n was determined to be 0.5, α ₁ was 4.27, and α ₂ was 0. The result of plotting the recording power Pw calculated by substituting the recording speed into the equation (2) is the same as in FIG. 15, and the calculated recording power coincides with the optimum recording power.

  As a result of performing CAV recording using this recording power adjustment method, the same results as in FIG. 17 are obtained. By using this recording power adjustment method, CAV recording that provides high-speed recording and good signal quality can be realized. confirmed.

[Example 4]
In the present embodiment, the result of adjusting the recording power of CAV recording using equation (4) as an approximate expression will be described. The parts that are not changed are the same as those in the first embodiment and the other embodiments related to the first embodiment, and thus detailed description thereof is omitted here.

The relationship between the recording speed ratio and the optimum recording power ratio in FIG. 11 was fitted by equation (4) to determine the parameters of equation (4). In the fitting, each parameter was adjusted so that the sum of the square error of the data and Equation (4) was minimized. Specifically, the measured recording speed ratio and the optimum recording power ratio are (vi / v1, Pi / P1) (i = 2, 3,...; Measurement point index), and at each recording speed ratio vi / v1. Calculate the square of the difference between the optimum recording power ratio (vi / v1) ⁿ + α ₃ calculated from the approximate expression and Pi / P1, and reduce the sum of the squares of the differences of all points to the minimum. Parameters n and α ₃ were determined. As a result, n was determined to be 0.5 and α ₃ was determined to be 0. The reference recording speed v1 in equation (4) is 2x, and the 2x recording power P1 is 6 mW. The result of plotting the recording power Pw calculated by substituting the recording speed into the equation (4) is the same as in FIG. 15, and the calculated recording power coincides with the optimum recording power.

  As a result of performing CAV recording using this recording power adjustment method, the same results as in FIG. 17 are obtained. By using this recording power adjustment method, CAV recording that provides high-speed recording and good signal quality can be realized. confirmed.

[Example 5]
In the present embodiment, the result of performing CAV recording by adjusting the recording power using an optical disc having different thermal characteristics from that of the first embodiment will be described. The parts that are not changed are the same as those in the first embodiment and the other embodiments related to the first embodiment, and thus detailed description thereof is omitted.

First, the optimum recording power at each recording speed was calculated according to the flow S10 in FIG. It is common to make the channel bit length 1T of the recording waveform proportional to the recording speed, and the reproduction signal quality (bER) at the optimum recording power at each recording speed is obtained using multipulse, monopulse, L-type, and castle-type recording waveforms. The measurement results are shown in FIG. In the figure, the case where the recording power proportional to Pw is changed in each recording waveform is also shown. From FIG. 20, it can be seen that the power adjustment method that gives a good signal quality (bER <10 ⁻⁵ ) even with a change in recording speed in the medium is as follows.

1. Mono pulse and fixed ratio of Pw and Ps 2. Fixed ratio of Pw, Pm and Ps in L type. It is a castle type and the ratio of Pw and Pm is fixed. In the castle type, the ratio of Pw, Pm, and Ps is fixed. In this embodiment, the recording power adjustment is performed using the power adjustment method (3).

Next, according to S11 of FIG. 6, in the determined power adjustment method, the relationship between the recording speed and the optimum recording power is plotted, fitting is performed using equation (1), and the parameters α1, n in equation (1) are calculated. went. In the fitting, each parameter was determined so that the sum of the square error of the data and Equation (1) was minimized. In addition to this method, the logarithm of the optimum recording power of data and the logarithm of recording speed may be linearly approximated, and the slope of the approximate straight line may be calculated as n and the y intercept as the logarithm of α1. The calculated n was determined to be 0.75 and α ₁ was determined to be 0.54.

  CAV recording was performed on the entire disk surface using the equation (1) in which the parameters were determined (FIG. 6, S12). The result is shown in equation (1) in FIG. Since the recording signal quality when using the recording power adjustment method is good regardless of the radius, it was confirmed that CAV recording can be realized by the recording power adjustment.

In this embodiment, the recording power is adjusted by using the expression (1), but the expressions (2), (3), and (4) can be used as an approximate expression of the recording speed and the optimum recording power. FIG. 21 also shows the measurement result of the recording signal quality at each radial position when the recording power adjustment is performed using the equations (2) to (4). The parameter calculation method of each equation is the same as the method described in each of Examples 2 to 4, and thus description thereof is omitted. Regarding the calculated parameters, n = 0.75 and α ₁ = 0.54 in the equation (1), but n = 0.7, α ₁ = 0.66, α ₂ = − in the equation (2). It was 0.2, and there was a slight difference in the approximate expression. This difference was also observed for formula (3) (n = 0.5) and formula (4) (n = 0.52, α ₃ = −0.1). This is because the medium of this embodiment has poor approximation accuracy in Equation (1) and Equation (3), and it is necessary to consider the parameter corresponding to the offset as in Equation (2) and Equation (4). Show. The variation in the recording signal quality in each equation in FIG. 21 is due to the approximation accuracy. However, since the variation is very small, it can be seen that good CAV recording can be realized for any of the media of the present embodiment using any of the equations (1) to (4).

  In this embodiment, the above-described method 1 is used as the power adjustment method. However, when other 1, 2, and 4 are used, the same recording power adjustment as described above is realized, and high-speed CAV recording is performed. It is feasible.

  Further, in this embodiment, the power adjustment method and the parameters of the approximate expression are determined in steps S10 and S11 in FIG. 6. However, by storing these in the storage unit in FIG. S11 can be omitted. Further, by storing these parameters in advance in DI (Disc Information) 102 in the management area 101 of the optical disc 100 shown in FIG. 18, steps S10 and S11 shown in FIG. 6 can be omitted in the subsequent recording. It is possible to shorten the time until the recording start S12. For this purpose, the disk manufacturer determines in advance the power adjustment method, approximate expression parameters, reference recording speed and reference optimum recording power by means similar to S10 and S11 in FIG. It is desirable to memorize. In addition, when these parameters are determined by the optical disk device, they can be stored in the management area 101 or stored in the storage unit of the optical disk device so that they can be read out and used when necessary. Recording power adjustment can be performed in a short time.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

10: Optical disk 12: Spindle motor 14: Optical pickup unit 16: Laser light 18: Encoder 20: LD drive unit 22: Control unit 24: Level calculation unit and RF signal processing unit 26: Decoder 100: Optical disk 101: Management area 102: DI (Disc Information)

Claims (18)

A method of adjusting the recording power of laser light for recording on an optical information recording medium,
Calculating an optimum recording power P at each recording speed v;
Calculating a recording speed ratio v / v1 and an optimum recording power ratio P / P1 using a reference recording speed v1 and an optimum recording power P1 at the recording speed v1;
By fitting the recording speed ratio v / v1 and the optimum recording power ratio P / P1 with the approximate expression P / P1 = (v / v1) ⁿ or P / P1 = (v / v1) ⁿ + α ₃ , the parameter n Or determining n, α ₃ ;
Target recording speed v, the recording speed v1, the optimum recording power P1 and the parameter n or n, with alpha _3, the approximate equation P / P1 = (v / v1 ) n or P / P1 = (v / v1 ) Calculating the target optimum recording power P from ⁿ + α ₃ ;
Setting the target optimum recording power P to the recording power at the target recording speed v;
A recording power adjustment method comprising: The recording power adjustment method according to claim 1,
The step of calculating the optimum recording power P at each recording speed v includes:
The recording waveform is a castle type,
The maximum recording power in the recording waveform is Pw, the next higher recording power Pw is Pm,
Making the channel clock length T of the recording waveform proportional to each recording speed;
Changing at least the recording power Pm in proportion to the recording power Pw;
Recording a signal using a plurality of types of the recording power Pw at each recording speed;
Determining the optimum recording power P as the recording power Pw with the best signal quality;
A recording power adjustment method comprising: The recording power adjustment method according to claim 1,
The step of calculating the optimum recording power P at each recording speed v includes:
The recording waveform is multipulse,
The maximum recording power in the recording waveform is Pw, the recording power next to the recording power Pw is Ps,
Making the channel clock length T of the recording waveform proportional to each recording speed;
Changing at least the recording power Pm in proportion to the recording power Pw of the recording waveform;
Recording a signal using a plurality of types of the recording power Pw at each recording speed;
Determining the optimum recording power P as the recording power Pw with the best signal quality;
A recording power adjustment method comprising: The recording power adjustment method according to claim 1,
The step of determining the parameter n of the approximate expression P / P1 = (v / v1) ⁿ is:
Linearly approximating the logarithm of the recording speed ratio v / v1 and the logarithm of the optimum recording power ratio P / P1;
Determining the slope of the approximate line as the parameter n;
A recording power adjustment method comprising: A method of adjusting the recording power of laser light for recording on an optical information recording medium,
Calculating an optimum recording power P at each recording speed v;
The parameters α ₁ , n or α ₁ , n, α ₂ are determined by fitting the recording speed v and the optimum recording power P with an approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α _2. Steps to do,
Using the target recording speed v and the parameters α ₁ , n or α ₁ , n, α ₂ , the target optimum recording power P is obtained from the approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α _2. A calculating step;
Setting the target optimum recording power P to the recording power at the target recording speed v;
A recording power adjustment method comprising: The recording power adjustment method according to claim 5,
The step of calculating the optimum recording power P at each recording speed v includes:
The recording waveform is a castle type,
The maximum recording power in the recording waveform is Pw, the next higher recording power Pw is Pm,
Making the channel clock length T of the recording waveform proportional to each recording speed;
Changing at least the recording power Pm in proportion to the recording power Pw;
Recording a signal using a plurality of types of the recording power Pw at each recording speed;
Determining the optimum recording power P as the recording power Pw with the best signal quality;
A recording power adjustment method comprising: The recording power adjustment method according to claim 5,
The step of calculating the optimum recording power P at each recording speed v includes:
The recording waveform is multipulse,
The maximum recording power in the recording waveform is Pw, the recording power next to the recording power Pw is Ps,
Making the channel clock length T of the recording waveform proportional to each recording speed;
Changing at least the recording power Pm in proportion to the recording power Pw of the recording waveform;
Recording a signal using a plurality of types of the recording power Pw at each recording speed;
Determining the optimum recording power P as the recording power Pw with the best signal quality;
A recording power adjustment method comprising: The recording power adjustment method according to claim 5,
The step of determining the parameters α ₁ and n of the approximate expression P = α ₁ × v ⁿ is
Linearly approximating the logarithm of the recording speed ratio v / v1 and the logarithm of the optimum recording power ratio P / P1;
Determining the slope of the approximate line as the parameter n and the P / P1 intercept of the approximate line as the logarithm of the parameter α ₁ ;
A recording power adjustment method comprising: A method of adjusting the recording power of laser light for recording on an optical information recording medium,
Calculating an optimum recording power P at each recording speed v;
Calculating a recording speed ratio v / v1 and an optimum recording power ratio P / P1 using a reference recording speed v1 and an optimum recording power P1 at the recording speed v1;
By fitting the recording speed ratio v / v1 and the optimum recording power ratio P / P1 with the approximate expression P / P1 = (v / v1) ⁿ or P / P1 = (v / v1) ⁿ + α ₃ , the parameter n Or determining n, α ₃ ;
A recording power adjustment method comprising: A method of adjusting the recording power of laser light for recording on an optical information recording medium,
Calculating an optimum recording power P at each recording speed v;
The parameters α ₁ , n or α ₁ , n, α ₂ are determined by fitting the recording speed v and the optimum recording power P with an approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α _2. Steps to do,
A recording power adjustment method comprising: The optimum recording power at the recording speed v is P, the optimum recording power at the reference recording speed v1 is P1,
Approximate expression P / P1 = (v / v1) ⁿ or P / P1 = (v / v1) ⁿ + α ₃ representing the relationship between the recording speed ratio v / v1 and the optimum recording power ratio P / P1 and the above a step of reading the optimum recording power P1 and the parameter n or n, the alpha ₃ from the optical information recording medium or information recording and reproducing apparatus,
Target recording speed v, the recording speed v1 read as well, the optimum recording power P1 and the parameter n or n, with alpha _3, the approximate equation P / P1 = (v / v1 ) n or P / P1 = ( v / v1) calculating a target optimum recording power P from ⁿ + α ₃ ;
Setting the target optimum recording power P to the recording power at the target recording speed v;
Recording on the optical information recording medium with the set recording power;
A recording power adjustment method comprising: P is the optimum recording power at the recording speed v,
Approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α ₂ parameter α ₁ , n or α ₁ , n, α ₂ representing the relationship between the recording speed v and the optimum recording power P is optical information. Reading from a recording medium or an information recording / reproducing device;
Using the target recording speed v and the read parameters α ₁ , n or α ₁ , n, α ₂ , target optimum recording from the approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α ₂ Calculating power P;
Setting the target optimum recording power P to the recording power at the target recording speed v;
Recording on the optical information recording medium with the set recording power;
A recording power adjustment method comprising: In an optical information recording medium having a data area and a management area,
When the optimum recording power at the recording speed v is P and the optimum recording power at the reference recording speed v1 is P1,
Approximation representing the relationship between the recording speed ratio v / v1 and the optimum recording power ratio P / P1 type P / P1 = (v / v1 ) n or P / P1 = (v / v1 ) the recording velocity v1 and the optimum ⁿ + alpha ₃ An optical information recording medium, wherein a recording power P1 and parameters n or n, α ₃ are recorded in the management area. In an optical information recording medium having a data area and a management area,
When the optimum recording / reproducing power at the recording speed v is P,
The parameter α ₁ , n or α ₁ , n, α _{2 of the} approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α ₂ representing the relationship between the recording speed v and the optimum recording power P is the management. An optical information recording medium recorded in an area. An information recording apparatus for recording by irradiating an optical information recording medium with laser light,
The optimum recording power P at each recording speed v is calculated,
Using the recording speed v1 as a reference and the optimum recording power P1 at the recording speed v1, the recording speed ratio v / v1 and the optimum recording power ratio P / P1 are calculated,
The recording speed ratio v / v1 and the optimum recording power ratio approximate equation P / P1 P / P1 = ( v / v1) n or P / P1 = (v / v1 ) Parameter n or by fitting with ⁿ + alpha ₃ determine n, α ₃ ,
Target recording velocity v, and the recording speed v1, the optimum recording power P1 and the parameter n or n, with alpha _3, the approximate equation P / P1 = (v / v1 ) n or P / P1 = (v / v1) from ⁿ + ^α ₃ calculates the target optimum recording power P,
Setting the target optimum recording power P to the recording power at the target recording speed v;
Recording on the optical information recording medium with laser light of the set recording power,
An information recording apparatus characterized by that. An information recording apparatus for recording by irradiating an optical information recording medium with laser light,
The optimum recording power P at each recording speed v is calculated,
The parameters α ₁ , n or α ₁ , n, α ₂ are determined by fitting the recording speed v and the recording power P with an approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α _2. ,
Using the target recording speed v and the parameters α ₁ , n or α ₁ , n, α ₂ , the target optimum recording power P is obtained from the approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α _2. Calculate
Setting the target optimum recording power P to the recording power at the target recording speed v;
Recording on the optical information recording medium with laser light of the set recording power,
An information recording apparatus characterized by that. An information recording apparatus for recording by irradiating an optical information recording medium with laser light,
When the optimum recording power at the recording speed v is P and the optimum recording power at the reference recording speed v1 is P1,
Approximate expression P / P1 = (v / v1) ⁿ or P / P1 = (v / v1) ⁿ + α ₃ representing the relationship between the recording speed ratio v / v1 and the optimum recording power ratio P / P1 and the above optimum recording power P1 and the parameter n or n, read from the information recording apparatus for recording an alpha ₃ in the management area or the optical information recording medium of the optical information recording medium,
Target recording speed v, the recording speed v1 read as well, the optimum recording power P1 and the parameter n or n, with alpha _3, the approximate equation P / P1 = (v / v1 ) n or P / P1 = ( v / v1) calculates the target optimum recording power P from the ⁿ + alpha _3,
Setting the target optimum recording power P to the recording power at the target recording speed v;
Recording on the optical information recording medium with laser light of the set recording power,
An information recording apparatus characterized by that. An information recording apparatus for recording by irradiating an optical information recording medium with laser light,
When the optimum recording power at recording speed v is P,
Approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α ₂ parameter α ₁ , n or α ₁ , n, α ₂ representing the relationship between the recording speed v and the optimum recording power P is optical information. Read from the management area of the recording medium or the information recording device that records on the optical information recording medium,
Using the target recording speed v and the read parameters α ₁ , n or α ₁ , n, α ₂ , target optimum recording from the approximate expression P = α ₁ × v ⁿ or P = α ₁ × v ⁿ + α ₂ Calculate power P,
Setting the target optimum recording power P to the recording power at the target recording speed v;
Recording on the optical information recording medium with the set recording power,
An information recording apparatus characterized by that.

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