JP4363322B2 - Optical information recording / reproducing apparatus - Google Patents

Description

  The present invention relates to an optical recording method and an optical disc recording apparatus for recording information by irradiating an optical disc medium with laser light to form a mark having a physical property different from that of an unrecorded portion, and information obtained by the optical recording method. The present invention relates to an optical disc medium including

  Conventional optical recording media include CD-R / RW, DVD-R / RW / RAM, and BD-RE media. An optical information recording / reproducing apparatus for recording information on these media and a recording power learning method include, for example, The method described in “DVD Specification for Re-Recorable Disc Part 1 Physical Specifications” or the method described in “Blu-ray Disc Rewirtable format part 1” is known. Further, regarding the recording power learning method using the initial value recording information in the disc, there are methods shown in Patent Document 1 and Patent Document 2. Further, there is a method disclosed in Patent Document 3 as a method for obtaining an appropriate writing condition for an optical disc in which write strategy data is not registered.

  In the rewritable and write-once optical recording media, the write strategy information describing the recommended recording power as the initial value information and the optical waveform at the time of writing is recorded in the initial value recording area. The optical information recording / reproducing apparatus can learn the recording power at an arbitrary timing using the initial value information as a clue.

  The initial value information is measured using a standard optical information recording / reproducing device that is managed before the shipment of the disc, and the signal quality is measured for each optical disc under a certain condition, and the recording power, the write strategy, etc. The recommended value for the disk has been determined. In the BD-RE, there are the following initial value information. Target recording power (Pind), modulation degree at target recording power (Mind), multiplication factor ρ for obtaining recommended recording power (Pwo) from the target recording power, limit recording power (Pth) at which marks can be written on the optical disk To a target recording power. The initial value information is held in the initial value recording area in the inner periphery of the disc in advance before shipping the disc.

  FIG. 8 shows an example of a conventional standard optical information recording / reproducing apparatus. A method for determining the recommended recording power (Pwo) using a standard optical information recording / reproducing apparatus will be described. The optical pickup 802 is moved to a recording power learning area 1002 provided on the inner periphery of the optical disc 801, and an arbitrary random data pattern modulated by 17PP is generated from the recording pattern generation circuit 811. As shown in FIG. 11, the recording power is increased by a constant power, and a signal is recorded in the recording power learning area 1002 with several levels of recording power.

  Each recorded reproduction signal waveform is obtained from the optical pickup 802, and the signal quality is measured by the signal quality measuring circuit 805. As a signal quality index, generally, a signal quality index such as jitter, bit error rate (bER), and MLSA (see Patent Document 3) correlated with the bit error rate when a signal processing circuit such as PRML is used is measured. The recording power with the best signal quality is set as the recommended recording power (Pwo).

  In addition, the modulation degree is detected at the same time as jitter measurement, a reproduction signal corresponding to each recording power Pw is reproduced from the optical pickup 802, and the modulation degree at each recording power is detected by the modulation degree detection circuit 807. The modulation degree detection circuit 807 calculates the modulation degree m using (Equation 1) from the amplitude levels I8H and I8L of the 8T space that is the longest space and the 8T mark that is the longest mark.

m = (I8H−I8L) / I8H (Formula 1)
The modulation coefficient calculation circuit 808 calculates the product of the modulation factor and the power at each recording power as shown in FIG. 12 from the relationship between the recording power and the modulation factor. The target recording power Pind at the target modulation degree Mind is set, and a tangent line 1201 is drawn using a measurement point of ± 10% in the vicinity of the target recording power Pind, and the intercept with the Pw axis is set as the limit recording power Pth.

  The recording power coefficient calculation circuit 813 calculates the power multiplication factor ρ and κ from the recommended recording power (Pwo), the target recording power Pind, and the limit recording power (Pth) using (Expression 2) and (Expression 3). .

ρ = Pwo / Pind (Equation 2)
κ = Pind / Pth (Equation 3)
Information such as ρ, κ, Pind, Mind, etc. thus obtained is recorded in advance on the disc as initial value information.
JP 2003-173560 A JP 2000-251254 A Japanese Patent Laid-Open No. 2004-246958 JP 2003-141823 A

  First, in the conventional method for determining the recommended recording power, the recommended recording power records the signal while changing the recording power, and the point where the reproduction signal quality is the best is the recommended recording power. However, when recording on an optical disc that can be recorded on one optical disc at two or more recording linear velocities, it is necessary to record recommended recording powers at the respective linear velocities in advance.

  As the recommended recording power, there is a method in which recording power characteristics are obtained at each linear velocity, and the recording power that provides the best signal quality is used as the recommended recording power. In this case, when overwriting with the recommended power of the second linear velocity on the track recorded with the recommended power of the first linear velocity, the mark recording formation condition slightly differs depending on the linear velocity. If the recommended power is recorded under a high power condition with respect to the recording power at the second linear velocity, the influence of the unerased portion is greatly affected at the time of overwriting and the signal quality is deteriorated.

  When determining the recommended recording power at two or more linear velocities, the mark formation (mark spread width and shape) of the track recorded on the base is effectively high when recording at other linear velocities. In the case of power, unerased parts are generated at the time of overwriting, and sufficient reproduction signal quality is not guaranteed.

  Secondly, in the conventional method for determining the recording power coefficients κ and ρ, the recording power having an arbitrary modulation degree (Mind) is set as the target power Pind, and a finite number of measurement points with the recording power changed in the vicinity of the Pind. The degree of modulation was measured, the limit power was obtained from the tangent line of the curve of the degree of modulation power product, and the coefficients κ and ρ were obtained. However, in the above method, the number of measurement points is finite, and it is easy to be affected by variations in measurement values. In addition, there is an error between the set value of the recording power and the actual output power due to the variation from drive to drive, changes over time, dust, etc., and the deviation from the power initially obtained by a standard optical information recording / reproducing device. Since the pin during learning is significantly different from the initial recording power, the slope of the tangent line near the pin of the modulation power product is shifted. There was a problem that the error of the limit power obtained by the deviation of the tilt occurred and the correct recording power was not learned.

  An object of the present invention is to determine a recommended recording power for obtaining good signal quality when recording at two or more linear velocities, and to determine an initial value recording condition capable of learning the recording power with high accuracy. And

In order to solve the above problems, an optical information recording apparatus of the present invention is an optical information recording / reproducing apparatus for recording / reproducing information on / from an optical information recording medium. Irradiating laser, recording power control means for controlling the laser power of the laser irradiation means to record signals with a plurality of recording powers on the optical information recording medium, and reproduction from the optical information recording medium Modulation degree detection means for detecting the modulation degree at the plurality of recording powers from the amplitude of the signal, and a modulation degree product that is a product of the modulation degree that is a detection value of the modulation degree detection means and the nth power of the recording power. Approximation to calculate and perform the least square approximation for the plurality of orders n from the values of the modulation degree products for the plurality of recording powers, and obtain the order n closest to the linear approximation as the linear approximation coefficient n Comprising a number calculating means, on the basis of the linear approximation coefficient n, the recording power calculating means for calculating a recommended recording power Pwo, and the initial value information reading means for reading the initial value information recorded on the optical information recording medium The recording power calculation means obtains the value of the recording power at the point where the modulation degree product is 0 at the point on the approximate line obtained with the linear approximation coefficient n as the limit power Pth ′, and the linear approximation from the product of the coefficient n and the limit power Pth 'and the initial value information, wherein Rukoto seek the recommended recording power Pwo.

In the optical information recording apparatus of the present invention, the linear approximation coefficient n is an integer of 0 or more and 0.5.
It is characterized by several times .

  As described above, according to the present invention, the base track is recorded with each recording power while changing the recording power, and each of the plurality of base tracks having different recording power is overwritten with a power that is a fixed multiple of the recording power, A recommended recording power is determined based on the signal quality of the plurality of overwritten tracks, various parameters relating to the recording power are determined from an approximate straight line obtained by multiplying the modulation characteristic with respect to the recording power by the power n, and the recording power By recording the recommended values and recording parameters on the optical disc in advance, the recording power fluctuation due to dust or dirt can be suppressed when the user performs recording / reproduction on the optical disc using the optical information recording / reproducing device. Highly accurate mark formation is possible. As described above, the recording / reproducing operation is highly reliable, and at the same time, the information recording apparatus and the recording medium can be miniaturized, which is advantageous in terms of cost.

  Embodiments of the present invention will be described below. In the present embodiment, a phase change optical disk will be described as an example of a recording medium. However, this does not limit the recording medium. Marks having physical properties different from those of unrecorded portions are injected by injecting energy into the recording medium. This is a technique common to recording media that record information by forming. In the embodiment of the present invention, a BD-RE (rewritable Blu-ray disc) will be described as an example. The main optical conditions are an objective lens with a wavelength of 405 ns and NA = 0.85, the disc structure is a phase change type optical disc having a track pitch of 0.32 μm and a substrate thickness of 75 μm to 100 μm, and the shortest mark length of recorded marks Is 0.138 μm to 0.160 μm.

  FIG. 1 is a diagram for explaining an example of the entire configuration of a standard optical information recording / reproducing apparatus according to the present invention. A standard optical information recording / reproducing device is a reliable evaluation device that is less dependent on the device with respect to temperature changes under certain environmental conditions, and in which physical conditions such as recording power and write strategy waveforms are managed. Etc.

  In FIG. 1, reference numeral 101 denotes an optical disk as an optical recording medium. As shown in FIG. 10, a data area 1001, a recording power learning area 1002 for learning recording power on the inner periphery side of the data area, and a recording power learning area. It is divided into an initial value recording area 1003 on the inner peripheral side. The data area is the area where user data is actually recorded on the optical disk.The recording learning area is the amount of change in recording power that occurs during startup or when temperature fluctuations occur before data is recorded in the user area. This area is used for test recording for adjustment. In the initial value recording area, a recommended value of recording power, a recommended value of write strategy, a recording linear velocity, a disk ID, and the like are recorded in advance for each disk. The read-only area is recorded in the form of being formed on the disk substrate.

  An optical pickup 102 is an optical pickup equipped with a laser diode (LD) for irradiating the optical disk 101 with a light beam, and 103 is a laser driving means for controlling and driving the laser output. 107 is a modulation degree detection means for detecting the modulation degree from the amplitude of the reproduction signal, 105 is a signal quality measurement means for measuring signal quality such as jitter, bit error rate (bER), MLSA, etc. of the reproduction signal, and 108 is the modulation degree detection. Approximation coefficient calculating means 113 for multiplying the modulation degree detected by the means to the nth power of the recording power to calculate the order n closest to the linear approximation and calculating the limit power Pth ′ at that time, 113 is obtained from the signal quality measuring means. The recording power coefficient calculating unit calculates a recommended recording power Pwo and calculates a target power multiplication factor κ, a recommended power multiplication factor ρ, and a target power Pind from the order n of the approximate coefficient calculating unit and the limit power Pth ′. Reference numeral 112 denotes recording power control means for setting recording power, and 111 denotes recording pattern generation means for generating a pattern to be recorded.

  A method for determining an initial value of a recording power parameter using the standard optical information recording / reproducing apparatus of the present invention configured as described above will be described with reference to the drawings.

  FIG. 2 shows an embodiment of the method for determining the recommended power and the recommended recording power coefficient of the present invention.

  A case will be described in which the initial value of the recommended recording power (Pwo) for an optical disc that can be recorded at a plurality of linear velocities is determined by a standard optical information recording / reproducing apparatus. FIG. 2 shows a flowchart, and FIG. 3 shows a cross power overwrite characteristic. The optical disc medium is rotated at the first linear velocity, and the recording power control unit sets the recording power to Pw = Pw1. The recording pattern generating means generates an arbitrary random signal, and the laser driving means drives the laser with the set recording power, and records signals on a plurality of tracks on the optical disk using the light irradiation means. Overwriting is performed once on the recorded track while changing the recording power. The reproduction signal quality of the reproduction signals from the plurality of tracks having different overwrite recording powers is measured by signal quality measuring means. The measured value is one of jitter, bit error rate, or MLSA (see Patent Document 4). When the power of α times the base recording power (α <100%) is Pwth1, if the measured signal quality at Pwth1 is not good with respect to the specified value X, the initial setting power (background recording power) is set. As Pw1 + Pd, the recording power is increased by Pd, and a plurality of base tracks are created again. Overwriting is performed once at a power α times (Pw1 + Pd), and the signal quality of the reproduced signal is measured by the signal quality measuring means. The above operation is repeated a plurality of times until the signal quality measured while changing the base power is close to the specified value X. The recording power Pw1 when the reproduction signal quality is close to the specified value X is determined as the recommended recording power Pwo1 of the first linear velocity.

  A similar procedure is performed at the second linear velocity.

  The recording power is set to Pw = Pw2. The recording pattern generating means also generates an arbitrary random signal, and the laser driving means drives the laser with the set recording power, and records signals on a plurality of tracks on the optical disk using the light irradiation means. Overwriting is performed once on the recorded track while changing the recording power. The reproduction signal quality is measured by the signal quality measurement means for the reproduction signals from the plurality of overwritten tracks having different recording powers. The measured value is one of jitter, bit error rate, or MLSA (see Patent Document 4). When the power of α times the base recording power (α <100%) is Pwth2, if the measured signal quality at Pwth2 is not good with respect to the specified value X, the initial setting power (background recording power) is set. As Pw2 + Pd, the recording power is increased by Pd and a plurality of base tracks are created again. Overwriting is performed once with a power of α times (Pw2 + Pd), and the signal quality of the reproduced signal is measured by the signal quality measuring means. The above operation is repeated a plurality of times until the signal quality measured while changing the base power is close to the specified value X. The recording power Pw2 when the reproduction signal quality is close to the specified value X is determined as the recommended recording power Pwo2 of the first linear velocity.

  FIG. 13 shows the cross power overwrite characteristics at the first linear velocity and the second linear velocity normalized with the respective recommended powers. In this case, the signal quality index MLSA is constant at 12% when overwriting is performed at a recording power that is α times the recommended power at either linear velocity. The ratio of recommended power is β = Pwo2 / Pwo1. In general, in a phase change recording material, when a mark is formed, the crystal is melted due to a temperature rise due to laser power irradiation, and an amorphous mark is formed by rapid cooling, but by increasing the linear velocity, Unless the amount of heat input per unit time is increased, the melting of the crystal does not occur. Therefore, when recording is performed at an increased linear velocity, the recording power must be increased, and the size and physical shape of the recording mark vary depending on the first linear velocity and the second linear velocity. However, according to the recommended power determination method described above, the standardized cross power characteristics show the same characteristics. Therefore, if the relationship between the recommended powers is effectively maintained in terms of the power of the ratio β, the groundwork The characteristics of the marks recorded in can be made equal. That is, even when overwriting at the second linear velocity is overwritten with the second linear velocity in the state in which the base track is created with the recommended power Pwo1 at the first linear velocity, the overwriting is performed with a power that is α times the second recommended power. The signal quality MLSA = about 12% means that compensation is made, and it is possible to achieve both the cross linear velocity and the cross power overwrite characteristic at different linear velocities.

  As specific numerical values, α = 85% is used here, the signal quality is determined using MLSA, and the specified value X = 12%.

  In particular, α is a cross power coefficient. In this case, even when overwritten with 85% of the recommended power, MLSA value = 12% is compensated. The cross power coefficient α is determined so as to satisfy various margins determined by the combination of the disk medium and the recording / reproducing apparatus. If the cross power coefficient is too small with the same detection value X, the recommended power is set to a high value. In this case, when performing repeated overwrite recording on the same track, recording is performed with high power. Damage due to heat is accumulated and signal quality deteriorates significantly. When the cross power coefficient is close to 1, the signal quality is significantly degraded due to the power reduction. From the above viewpoint, the power coefficient is practically desirable within a range satisfying a power margin of about 20%. Therefore, about α = 80% to 90% is a practically preferable coefficient.

  Although the detection reference value X is MLSA = 12%, a certain margin is estimated for the error correction capability from the viewpoint that the limit of error correction capability in BD is about MLSA = 15% to 16%. It is practically desirable to set the MLSA reference value of about 11% to 13 in order to maintain the quality of the reproduction signal. From the same viewpoint, when jitter is used as an indicator of signal quality, the jitter reference value is about 11% to 13% because the jitter value is about 15%, which is the limit of error correction capability. However, it is practically desirable to maintain the quality of the reproduction signal.

  In the above example, MLSA is used as an indicator of signal quality, but jitter or bit error rate may be used. In addition, the initial recording power Pw1 is gradually increased from a low power, but when recording is started from a power higher than the recommended power, the power is gradually decreased and the first power that falls below the specified value X May be the recommended power. Further, as the recommended power, the recording power that is one time the signal quality becomes X as the recommended recording power is used as the recommended recording power. The recommended recording power may be a power of about 0.95 times to 1.05 times the recommended powers Pwo1 and Pwo2.

  As described above, the base track is recorded at a high power, and the signal with the same signal quality when overwritten with a constant magnification power is used as the recommended power for each linear speed, thereby recording at the first linear speed. Good signal quality at the time of overwriting at the second linear velocity on the recorded underlying track, or at the cross linear velocity overwriting that occurs when the underlying track recorded at the second linear velocity is overwritten at the first linear velocity It is possible to keep on.

  Next, a method for determining the ratio of the cooling power to the peak power will be described.

  In general, the cooling power is determined in consideration of the SN of the signal amplitude, the erasing characteristic, the distortion of the reproduced signal waveform, and the like. FIG. 7 is a schematic diagram of the mark shape recorded on the phase change recording medium. FIG. 7 shows an example when the light beam is scanned from left to right. A mark 701 is formed, and a space 702 is a space between the marks. It can be seen that the end portion of the mark shape 701 is formed in a ginkgo shape with a tail. The method of forming the mark at the end portion often depends on the power of the cooling pulse, and by lowering the cooling power, the mark portion that becomes abruptly cooled and becomes amorphous becomes larger. The mark is erased and crystallized. At this time, when the power of the cooling pulse is particularly low, the trailing edge of the mark becomes noticeable, and the bit error rate may change sensitively due to a slight difference in cooling conditions within the disk. If the event occurs randomly due to SN such as noise, MLSA and jitter can be measured while changing the power level of the cooling pulse when determining the power level of the cooling pulse. Since the mark formed in the ginkgo shape is significantly affected by local bit errors, it is possible to improve the signal quality by measuring the bit error rate and determining the cooling power.

  Next, a method for determining the multiplication factors κ and ρ and the target power Pind among the recording power parameters will be described. FIG. 4 shows a flowchart. The light irradiation means 102 is moved to a recording power learning area 1002 provided in the inner periphery of the optical disc 101 to generate an arbitrary random signal from the recording pattern generation circuit 111 and the recording power control means 112 sets the recording power at a constant interval. The recording signals are recorded on different tracks in the learning area 1002 with k powers, respectively, while increasing in step.

  A reproduction waveform corresponding to each recording power Pw (i) is reproduced, and the modulation degree at each recording power is detected by the modulation degree detection means 107. The modulation degree detection means 107 calculates the modulation degree m using (Equation 4) from the amplitude levels I8H and I8L of the 8T space that is the longest space and the 8T mark that is the longest mark.

m = (I8H−I8L) / I8H (Formula 4)
As shown in FIG. 5, the approximation coefficient calculation means 108 calculates the product of the nth power of the recording power and the modulation degree at that time from the value of the recording power and the modulation degree, and calculates the minimum of the calculation result for each recording power. A square approximation is performed for each order n. The order n closest to the straight line approximation is determined and set as the approximate straight line 501. At this time, the order n is not an arbitrary real number, but the calculation is simplified by using, for example, an integer multiple of 0.5 as a unit.

  The modulation degree curve when approximated is expressed by the following (formula 5).

m = m0 × (Pw−Pth ′) / Pw ^ n (Expression 5)
The recording power coefficient calculation means 113 uses the value of the order n to draw a tangent line 501 using a measurement point of ± 10% in the vicinity of the target recording power Pind, and to set the intercept with the Pw axis as the limit recording power Pind (i ) (I = 1, 2, 3,...), The limit power Pth ′ (i). FIG. 6 shows the relationship of Pth ′ with respect to Pind (i).

  In FIG. 6, in the case of CASE 1, when the linearity is very good in all the measurement point intervals, even if Pth ′ is calculated in the interval of Pin ± 10% around any Pin, the same Pth ′ value is obtained. However, when the linearity fluctuates depending on the power interval as in CASE 2, the value of Pth ′ varies depending on the value of Pind. This is likely to occur when n <1. Pth ′ is calculated for a plurality of Pind within a range of Pind ± 10%, and an A point with a small amount of change in Pth ′ is selected as Pind.

  However, if a point with a low modulation degree is used, a large error occurs. Therefore, when selecting a Pind, it is preferable to use a Pin with a modulation degree of 30% or more in both conditions.

  In this example, the signal to be recorded at the time of measuring the modulation degree is a 17PP random signal, but it is also possible to record a repetitive signal of a longest code single signal in 17PP modulation such as an 8T single signal. Is possible. In this case, since the recording signal is a single signal, the influence of intersymbol interference can be suppressed, and the modulation factor can be measured with good signal quality, and the recording power can be used to determine the initial value of the recording power. Effective in improving the accuracy of determination.

  Next, a method for calculating κ will be described.

  As shown in FIG. 12, κ is expressed by the following (formula 6) using the limit power Pth of the intercept at which the tangent 1201 at the target recording power Pind of the curve obtained by multiplying the modulation power by the recording power intersects the recording power axis. .

κ = Pind / Pth (Formula 6)
Therefore, now, assuming that the modulation degree curve can be expressed by an approximation curve of the order n as shown in (Expression 5), the modulation degree power product of FIG. 12 becomes (Expression 7).

  m × Pw = m0 × (Pw−Pth ′) / Pw ^ (n−1) (Expression 7)

  Since the recording power of (Equation 7) is a linear slope that is a single derivative at Pind, and (Equation 7) passes through (Pind, m0 × (Pind−Pth ′) / Pind ^ (n−1)), Solving these simultaneous equations gives (Equation 8).

κ = [(2-n) Pind + (n−1) Pth ′] / [nPth ′ − (n−1) Pind] (Equation 8)
Therefore, κ is calculated using the above-mentioned order n and the target recording power Pind.

  Next, a method for calculating ρ will be described. In FIG. 12, the multiplication factor ρ is expressed by the following (formula 9).

ρ = Pwo / Pind (Equation 9)
The multiplication factor ρ is calculated by calculating (Equation 9) using Pwo and Pind described above.

  As described above, from the approximate curve obtained by multiplying the degree of modulation by the nth power of the recording power, the target power Pind with the least amount of change in Pth ′ with respect to the change in Pind is determined, so that accurate recording with little learning error is achieved. Data can be recorded on the optical disc with power, and the read reliability of the optical disc can be improved.

  In addition, the above-described target power and multiplication factor determination method is performed in the same procedure for the second linear velocity, and the second linear velocity target power Pind and multiplication factors κ and ρ are determined.

  The recommended power and the recommended recording power coefficient at each linear velocity determined as described above are recorded in the initial value recording area in the inner periphery of the optical disk, and the disk is shipped.

  Next, a method of learning recording power using an optical disc on which initial value information such as recommended power is recorded using the standard optical information recording / reproducing apparatus will be described.

  FIG. 9 shows a BD-RE recording / reproducing apparatus which is an example of an optical information recording / reproducing apparatus. An optical information recording medium (BD-RE medium) is an optical disc 901 and the optical disc 901 is irradiated with a light beam. An optical pickup 902 equipped with a laser diode (LD), a laser driving circuit 903 for driving the LD in the optical pickup 902, a laser output control circuit 904 for instructing a desired laser output to the laser driving circuit 903, An initial value information reading circuit 906 for reading the initial value information recorded on the optical disc 901, a recording power variable circuit 912 for changing the recording power based on the read initial value information, and a modulation degree of the reproduction signal are detected. Modulation degree detection circuit 907, the modulation degree detected from the modulation degree detection circuit 907, and the recording power n , An approximation coefficient calculation circuit 908 for calculating the order n closest to the linear approximation and calculating a limit power Pth ′ at that time, a target power multiplication factor κ described in the disk from the initial information reading circuit, and a recommendation A recording power calculation circuit 913 for calculating a recommended recording power Pwo from a power multiplication factor ρ, a target power Pind, an order n of the approximation coefficient calculation circuit, and a limit power Pth ′; a recording pattern generation circuit 911 for generating a pattern to be recorded; It is composed of

  On the optical disc 901, as shown in FIG. 10, when the user records information on the inner periphery of the optical disc 901 other than the data region 1001 for recording arbitrary information, a recording power learning region 1002 for learning recording power as necessary. Is provided. Furthermore, there is an initial recording area 1003 having initial value information recorded in advance at the time of shipment of the disc on the inner periphery.

  The optical pickup seeks to the inner periphery of the disc and reads the initial value recording information. The recording learning area is sought, recording is performed while changing the recording power with the power in the vicinity of Pind, a reproduction waveform corresponding to each recording power Pw is reproduced, and the modulation degree at each recording power is detected by the modulation degree detection means 907. Is done. The modulation degree detection circuit 907 calculates the modulation degree m from the amplitude levels I8H and I8L of the 8T space, which is the longest space, and the 8T mark, which is the longest mark, using the above (Equation 4).

  As shown in FIG. 5, the approximate coefficient calculation circuit 908 calculates the product of the nth power of the recording power and the modulation factor at that time from the value of the recording power and the modulation factor, and calculates the minimum of the calculation result for each recording power. A square approximation is performed for each order n. The order n closest to the straight line approximation is determined and set as the approximate straight line 501. At this time, the order n is not an arbitrary real number, but the calculation is simplified by using, for example, an integer multiple of 0.5 as a unit.

  The modulation degree curve when approximated is expressed by the following (Formula 5).

  The recording power calculation circuit 913 draws the tangent line 501 using the value of the order n, and sets the intercept with the Pw axis as the limit recording power Pth ′.

  The recording power calculation circuit calculates the following (Expression 10) and (Expression 11) using the Pth ′ and the initial value recording information κ and ρ.

Pth = Pth ′ × ((1-n) + nκ) / ((2-n) κ + (n−1) κ ^ 2)
.... (Formula 10)
Pind2 = − ((n −) − nκ) / ((n−1) κ + (2-n))
... (Formula 11)
Here, if Pin 2 obtained by (Equation 11) is different from the initial value Pind read from the disc by 5% or more, Pind is again used as Pin2 to obtain the modulation characteristic again in the vicinity of Pind2, and the initial value recording information Are used to repeat the operations of (Equation 10) and (Equation 11).

  Next, the optimum power Pwo obtained by performing the calculation of the following (formula 12) is determined as the optimum power after learning.

  Pwo = κ × ρ × Pth (Equation 12)

  INDUSTRIAL APPLICABILITY The optical recording / reproducing method and the optical recording / reproducing apparatus for the optical disc medium of the present invention have the effect of high-density recording on the optical recording medium, and can be used in the electric appliance industry including digital home appliances and information processing apparatuses. .

The figure explaining the whole structure of the optical information recording and reproducing apparatus by this invention Explanatory drawing of the initial value determination method of recording power by embodiment of this invention Explanatory drawing of the cross power overwrite characteristic by embodiment of this invention Explanatory drawing of the initial value determination method of recording power by embodiment of this invention Explanatory drawing of the characteristic of the product of the nth power of the recording power approximated by the straight line and the modulation factor according to the embodiment of the present invention Explanatory drawing showing the relationship between the target power and limit power by embodiment of this invention The figure explaining the mark shape by embodiment of this invention The figure explaining the whole structure of the conventional standard optical information recording / reproducing apparatus. The figure explaining the whole structure of the optical information recording / reproducing apparatus of this invention The figure explaining a structure of a structure of an optical information recording medium Diagram explaining the relationship between the modulation factor and the jitter for the recording power A diagram for explaining the relationship between the power of modulation and the power at each recording power Explanatory drawing of the cross power overwrite characteristic normalized with the recommended power by embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Optical disk 102 Light irradiation means 103 Laser drive means 105 Signal quality measurement means 107 Modulation degree detection means 108 Approximation coefficient calculation means 112 Recording power control means 113 Recording power coefficient calculation means 1002 Recording power learning area 1003 Initial value recording area

Claims (2)

An optical information recording / reproducing apparatus for recording / reproducing information on / from an optical information recording medium,
Laser irradiation means for irradiating the optical information recording medium with a light beam;
Recording power control means for controlling the laser power of the laser irradiation means on the optical information recording medium to record signals with a plurality of recording powers;
A degree of modulation detecting means for detecting the degree of modulation at the plurality of recording powers from the amplitude of a reproduction signal from the optical information recording medium;
A modulation factor product that is a product of the modulation factor that is a detection value of the modulation factor detector and the nth power of the recording power is calculated, and a least square approximation is calculated from the values of the modulation factor products for the plurality of recording powers. An approximation coefficient calculating means for performing a plurality of orders n and obtaining the order n closest to the linear approximation as the linear approximation coefficient n;
A recording power calculation means for obtaining a recommended recording power Pwo based on the linear approximation coefficient n ;
Initial value information reading means for reading initial value information recorded on the optical information recording medium ,
The recording power calculation means obtains the value of the recording power at the point where the modulation degree product is 0 at a point on the approximate line obtained when the linear approximation coefficient n is obtained as the limit power Pth ′, and the linear approximation coefficient the optical information recording and reproducing apparatus from the product Ru determined the recommended recording power Pwo of n and the limit power Pth 'and the initial value information. 2. The optical information recording / reproducing apparatus according to claim 1 , wherein the linear approximation coefficient n is 0 or more and an integer multiple of 0.5.

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