JP2006155695A - Optical beam irradiation condition setting method and optical disk device utilizing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device in which optimum laser irradiation conditions when recording is carried out for an optical disk can be set. <P>SOLUTION: This apparatus is provided with an optical pickup 3 forming a recording mark line corresponding to each irradiation condition on a track by irradiating an optical disk 1 having a track in which information is recorded as a recording mark with a light beam varying irradiation conditions for a plurality of kinds, a DPD signal generating part 15 generating a DPD signal indicating a value in which degree of deviation from the prescribed reference of a recording mark shape on the track is reflected, a noise calculating part 18 generating DPD signals corresponding to irradiation conditions of a plurality of kinds respectively and calculating variation of values varying in one of the DPD signals for each of a plurality of kinds of the DPD signals, and a control part 16 selecting the irradiation condition of the light beam corresponding to a deviation degree signal in which variation becomes the minimum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for setting light beam irradiation conditions when data is recorded on an optical disk.

  In recent years, there are various optical disks capable of recording and / or reproducing data. Specific examples of such an optical disc include CD-R (Compact Disc-Recordable), CD-RW (Compact Disc-ReWritable), DVD-R (Digital Versatile Disc-Recordable), DVD-RW (Digital Versatile Disc-ReWritable). DVD + RW (Digital Versatile Disc + ReWritable). A guide groove called a track is formed on the surface of these optical discs, and tracking control is performed so that a beam spot of a laser beam (light beam) follows the guide groove.

  Examples of the tracking control method include a differential push-pull method and a push-pull method as disclosed in Patent Document 1. However, when reproducing data on an optical disc, there is a tracking control method called DPD method (Differential Phase Detection) in addition to the above method.

  The DPD method is used for a reproduction-only optical disc as described in non-patent literature. First, as shown in FIG. 12, one of four regions formed by dividing a light receiving surface of a light receiving element that receives reflected light into four points symmetrically is defined as a first region. In addition, the regions arranged counterclockwise from the first region are sequentially referred to as a second region, a third region, and a fourth region. Therefore, the first region and the third region are in a diagonal positional relationship with each other, and the second region and the fourth region are also in a diagonal positional relationship with each other.

  In addition, the signal which the said 1st area | region produces | generates based on the received reflected light is made into a 1st signal, and similarly the signal corresponding to the said 2nd-4th area | region is made into the 2nd-4th signal.

  In the DPD method, the signal waveform in the sum of the first signal and the third signal and the sum of the second signal and the fourth signal has a phase difference that occurs in the time direction in proportion to the tracking error. It is a method of detection. The phase difference is caused by the interference effect of diffracted light by the pit row.

  Incidentally, as described above, the DPD method is a tracking control method used for a reproduction-only optical disc. However, the reproduction signal of the recorded area in the rewritable or write-once optical disc is obtained from the reproduction-only optical disc. Since it is intended to be equivalent to a reproduced signal to be reproduced, tracking control by the DPD method can be performed in such a recorded area.

  As described above, in the recording / reproducing apparatus, the beam spot of the laser beam is controlled along the track to record / reproduce data.

  FIG. 13 shows an example of a laser light drive waveform when data is recorded. FIG. 13A shows an example of recording data recorded on the optical disc, and FIG. 13B shows an example of a driving waveform of laser light.

  When recording a mark on an optical disk, as shown in FIG. 13, the recording / reproducing apparatus drives a semiconductor laser with a drive signal composed of a pulse train so as to output a high-power laser beam. In addition, the pulse peak value and the optimum value of the pulse interval in the laser light driving waveform differ depending on the optical disk. Therefore, a standard irradiation condition value is recorded in advance on the optical disc, and the recording / reproducing apparatus sets the irradiation condition value based on the standard value and records data. . The pulse peak value is the height of the drive waveform (Y in the figure) as shown in FIG. 13 (b). Further, the pulse interval is a rising interval between adjacent pulses forming a drive waveform (X in FIG. 13; from a rising edge to an adjacent rising edge) as shown in FIG. 13B.

  However, the standard value recorded on the optical disc is the standard value of an optical disc manufactured in a certain unit of quantity (lot). Therefore, the optimum value of the irradiation condition varies depending on the optical disc due to individual variations in optical disc manufacture. Further, when the ambient temperature at the time of recording changes, the optimum value of the irradiation condition also changes in the same type of optical disc.

  For this reason, in a general optical disc apparatus, when the optical disc is changed or the ambient temperature changes greatly, user data is recorded by performing test writing in a test recording area provided in advance on the optical disc. Set the drive waveform for the case.

  As a technique related to a method of performing trial writing for setting the drive waveform, for example, Patent Document 2 is disclosed.

  As shown in FIG. 14, the optical disc apparatus disclosed in Patent Document 2 includes an optical pickup 93, a reproduction data output unit 94, a clock generation unit 95, a jitter detection unit 96, and a control unit 97. ing. Then, the optical disc apparatus reads the record information recorded on the optical disc 91.

  The optical pickup 93 includes a light source that irradiates the optical disc 91 with laser light, an optical system device that includes an objective lens, a detection system device that includes a detector that receives reflected light from the optical disc 91, and a mechanism that includes an actuator. System equipment.

  The optical pickup 93 converts the received reflected light into a reproduction signal by the detection system device, and the reproduction signal is input to the reproduction data output unit 94. The reproduction data output unit 94 converts the inputted reproduction signal into reproduction data by performing waveform processing, and the reproduction data is inputted to the clock generation unit 95. Thereafter, the clock generation unit 95 generates a reproduction clock synchronized with the reproduction data from the inputted reproduction data, and the reproduction clock is input to the jitter detection unit 96. The jitter detector 96 detects the jitter, which is fluctuation of the recovered clock, based on the AC component of the demodulated signal by FM demodulating the input recovered clock, and the jitter is input to the controller 97. The

As a result, the optical disc apparatus always controls the laser beam so that the AC component of the demodulated signal becomes small when the optical disc is replaced or when the disc temperature change in the optical disc device exceeds a predetermined amount. A recording mark having a size can be formed, and the reproduction data output unit 94 can set reproduction signal condition with a small amount of jitter because the signal waveform equalization processing conditions are set so as to reduce the amount of jitter. For this reason, the optical disc apparatus disclosed in Patent Document 2 can optimize the drive waveform.
JP-A-2004-5859 (release date: January 8, 2004) Japanese Patent Laid-Open No. 9-147494 (publication date: June 6, 1997) Hirataro Nakajima and Hiroshi Ogawa "Illustrated Compact Disc Reader (3rd revised edition)", published by Ohmsha P.169-P.171 1996

  However, the above-described conventional configuration is based on the premise that a reproduction clock synchronized with reproduction data is generated as a jitter detection method.

  Generally, the recovered clock is generated by a PLL (Phase Lock Loop). Here, when the quality of the data recorded on the optical disk is good, the PLL can generate a reproduction clock synchronized with the reproduction data without any problem. However, in the above-described conventional configuration, the PLL at the stage where trial writing is performed in order to determine the laser irradiation condition cannot follow the reproduction data if the data quality is so bad that it cannot be synchronized with the reproduction data. At this time, the PLL oscillates at a preset free-running frequency, and outputs the clock of the free-running frequency to the jitter detection unit at the subsequent stage.

  As described above, when the PLL oscillates at the free-running frequency, the jitter detection unit detects the jitter of the clock that is not synchronized with the reproduction data. In the worst case, the recording quality is so bad that the PLL cannot follow. There arises a problem that the condition is adopted as the recording condition of the user data.

  In addition, in the above conventional configuration, in order to detect the jitter of the reproduction clock synchronized with the reproduction data, it is necessary to newly provide a jitter detection unit including an FM detection circuit in addition to the recording / reproduction function. There is also a problem that costs increase.

  The present invention has been made in view of the above problems, and its object is to eliminate the need for a new additional circuit and to erroneously adopt recording conditions in the case where the quality of data is very poor. It is to realize that the optimum laser irradiation conditions are always set.

  In order to solve the above problems, an optical disc device according to the present invention irradiates a light beam to an optical disc having a track on which information is recorded as a recording mark by changing the irradiation conditions in a plurality of ways. A value that reflects the degree of deviation of the recording mark shape from the predetermined reference in the track from the recording means for forming the recording mark row on the track and the reflected light when the recording mark row is irradiated with a reproducing light beam A deviation degree signal generating means for generating a deviation degree signal indicating the difference, and a calculation for calculating a variation of a value varying in one of the deviation degree signals corresponding to the plurality of irradiation conditions for each of the plurality of deviation degree signals. And control means for selecting the irradiation condition of the light beam corresponding to the deviation degree signal that minimizes the variation. .

  Further, in order to solve the above problems, the light beam irradiation condition setting method according to the present invention irradiates a light beam with a plurality of irradiation conditions changed to an optical disc having a track for recording information as a recording mark. Deviation of the recording mark shape on the track from a predetermined reference from the recording process for forming the recording mark row on the track according to each irradiation condition and the reflected light when the recording mark row is irradiated with the reproducing light beam A deviation degree signal generation step for generating a deviation degree signal indicating a value reflecting the degree of the deviation, and a deviation degree signal corresponding to the plurality of irradiation conditions are respectively generated, and a value that fluctuates in one of the deviation degree signals. A calculation process for calculating variation for each of a plurality of deviation degree signals, and a light beam irradiation condition corresponding to the deviation degree signal that minimizes the dispersion. Characterized by comprising a control step of selecting.

  The predetermined standard of the recording mark shape is a recording mark shape when the irradiation condition of the light beam when forming the recording mark is appropriate. / N) can be said to be a recording mark shape when exceeding the standard. The recording mark that satisfies the predetermined standard is formed, for example, without protruding on the track and without changing the width of the recording mark between the front and rear of the recording mark.

  Further, even in the case of a recording mark row formed on a track under the same irradiation conditions, various noises are superimposed on a signal generated based on the recording mark row. Therefore, the value of the deviation degree signal generated from the reflected light when the recording mark is irradiated with the reproducing light beam fluctuates and varies with the same irradiation condition.

  According to the configuration and the setting method described above, the deviation degree generation unit generates a deviation degree signal, and the calculation unit calculates the variation in the value generated in the deviation degree signal. I know the condition. Further, the calculation means calculates a variation in value generated in one of the deviation degree signals corresponding to the plurality of light beam irradiation conditions for all of the plurality of deviation degree signals, and the control means calculates the variation deviation signal. The light beam irradiation condition that minimizes is selected.

  Thereby, it is possible to always set the optimum light beam irradiation condition without erroneously adopting the light beam recording condition when the data quality is very poor.

  In the optical disk device of the present invention having the above configuration, the deviation signal generation unit generates a DPD signal using the DPD method as the deviation degree signal, and the arithmetic unit fluctuates in the DPD signal. It is preferable to calculate the variation of values.

  By using the DPD method for the deviation signal generation means, the influence of the pit depth on the optical disk can be reduced. That is, the deviation degree signal generation means uses the DPD method to output a tracking error signal even if the pit depth is λ / 4. Therefore, it is not necessary to strictly manage the pit depth. Further, the deviation degree signal generation means can be used as a tracking servo system because the influence of the beam movement on the detector in the optical disk apparatus is small by using the DPD method.

  Further, the DPD signal can be used as a tracking error signal when marks are properly formed on the recording medium. For this reason, if the tracking servo is applied in a state where the marks are properly formed, the DPD signal takes a substantially constant value. However, when the mark is not properly formed, the DPD signal becomes a signal including a lot of noise even when the tracking servo is applied.

  Therefore, according to the above configuration, it can be understood how much noise is included in the DPD signal by calculating a variation in the value generated in the DPD signal. Thereby, since the irradiation state of the laser beam in a plurality of different laser irradiation conditions is relatively known, it is possible to always select and set the optimal laser irradiation condition as compared with the case where other methods are used.

  Further, the DPD signal is generated based on a detector detection signal obtained by dividing the light receiving surface into four points symmetrically. Since the above detector is used for tracking control using a push-pull method, a differential push-pull method, or the like, it can also serve as a detector for generating a DPD signal and a detector for tracking control. Therefore, the deviation signal generation means of the present invention can be configured using the existing configuration, which is advantageous in terms of cost.

  In the optical disc apparatus of the present invention having the above-described configuration, it is preferable that the calculation unit calculates a standard deviation of the deviation degree signal value as the variation.

  According to said structure, the dispersion | variation in the said deviation degree signal is known by calculating | requiring the standard deviation of the said deviation degree signal. Accordingly, since the irradiation state of each signal, that is, the light beam in the light beam satisfying each light beam irradiation condition is known, the optimum light beam irradiation condition can always be selected and set.

  Furthermore, in the optical disk device of the present invention having the above-described configuration, it is preferable that the calculation unit calculates the variance of the deviation degree signal value as the variation.

  According to said structure, by calculating | requiring the dispersion | distribution of the said deviation degree signal, the dispersion | variation in the said deviation degree signal can be known, and calculation amount can be reduced rather than calculating | requiring a standard deviation. As a result, since the irradiation state of each signal, that is, the light beam that satisfies each irradiation condition, can be understood even when the amount of calculation is reduced, the optimal light is always reduced while reducing the load on the optical disk device. Beam irradiation conditions can be selected and set.

  In the optical disk device of the present invention, in the above-described configuration, it is preferable that the plurality of irradiation conditions are different in the pulse peak value of the light beam forming the recording mark.

  According to the above configuration, the plurality of irradiation conditions are determined mainly using the pulse peak value and the pulse interval. For this reason, the deviation signal corresponding to different pulse peak values can be relatively compared by changing the pulse peak value. Thereby, the optimum pulse peak value can be selected and set.

  Furthermore, in the optical disk apparatus according to the present invention, in the above-described configuration, it is preferable that the plurality of irradiation conditions differ in the pulse interval of the light beam forming the recording mark.

  According to the above configuration, the plurality of irradiation conditions are determined mainly using the pulse peak value and the pulse interval. For this reason, by changing the pulse interval, signals corresponding to different pulse intervals can be relatively compared. Thereby, an optimal pulse interval can be selected and set.

  As described above, the light beam irradiation condition setting method according to the present invention and the optical disk apparatus using the same are based on the reflected light when the recording mark row is irradiated with the reproduction light beam, and the recording mark shape in the track is recorded. A deviation degree signal generating means for generating a deviation degree signal indicating a value reflecting a degree of deviation from a predetermined reference, and a plurality of fluctuations of values that fluctuate in one of the deviation degree signals corresponding to the plurality of irradiation conditions. When the data quality is very poor because the calculation means for calculating each deviation degree signal and the control means for selecting the irradiation condition of the light beam corresponding to the deviation degree signal that minimizes the variation are provided. Thus, there is an effect that the optimum light beam irradiation condition can always be set without erroneously adopting the light beam recording condition.

Embodiment
An embodiment of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the optical disc apparatus according to the present embodiment includes an optical pickup (recording unit) 3, a signal detection unit 11, a tracking error signal generation unit 12, a DSP (Digital Signal Processor) 13, and a driver 14. And a DPD signal generation unit (deviation degree signal generation unit) 15 and a control unit (recording unit / control unit) 16. The optical pickup 3 irradiates the optical disc 1 with a light beam and guides the reflected light from the optical disc 1 to the signal detector 11. The reflected light is received by a detector 20 which will be described later as a component of the signal detection unit 11 for convenience.

  As shown in FIG. 2, the signal detection unit 11 includes a detector 20 and an I / V conversion unit 21 that converts a current signal into a voltage signal, and detects a signal that receives reflected light from the optical disc 1. . The signal detection unit 11 is usually arranged in the optical pickup 3. The signal detector 11 outputs the detected signal to the tracking error signal generator 12 and the DPD signal generator 15.

  The tracking error signal generation unit 12 calculates an input from the signal detection unit 11 and generates a tracking error signal by a push-pull method or a differential push-pull method. The optical disc apparatus of the present invention performs tracking control using the tracking error signal calculated by the tracking error signal generator 12. Then, the tracking error signal generator 12 outputs the tracking error signal to the servo means 17 that is performed by the DSP 13 described later.

  The DSP 13 performs servo system computation and performs noise computation on the DPD signal. The servo means 17 performed by the DSP 13 performs gain adjustment and phase compensation of the focus error signal and tracking error signal calculated by a focus error signal generator (not shown).

  The driver 14 drives an actuator (not shown) in the optical pickup 3 based on the output from the servo means 17.

  The DPD signal generation unit 15 generates a DPD signal by calculating the signal output from the signal detection unit 11. Then, the DPD signal generation unit 15 outputs the DPD signal to a noise calculation unit (calculation unit) 18 described later performed by the DSP 13.

  The noise calculator 18 calculates the standard deviation of the DPD signal. Then, the noise calculation unit 18 outputs the standard deviation of the DPD signal as an evaluation value to the control unit 16.

  The control unit 16 stores the evaluation value calculated by the noise calculation unit 18 in a storage unit (not shown). And the said control part 16 compares the said calculated evaluation value in each laser irradiation conditions (light beam irradiation conditions). Furthermore, by the comparison, the control unit 16 selects the one having the smallest evaluation value. When the evaluation value is selected, the control unit 16 transmits a laser irradiation condition corresponding to the evaluation value to a laser driver (not shown) in the optical pickup 3, and the laser driver sets the laser irradiation condition. Drive to the base. The control unit 16 is also a recording unit in the present invention.

  Each member will be described in detail below.

  As shown in FIG. 2, the signal detection unit 11 includes a detector 20 and an I / V conversion unit 21 that converts a current signal output from the detector 20 into a voltage signal.

  As shown in FIG. 2, the detector 20 includes four regions obtained by dividing the light receiving surface of the light receiving element that receives the light reflected by the recording medium into four points symmetrically. One of the four areas is defined as a first area 20a. In addition, the regions arranged counterclockwise from the first region 20a are sequentially referred to as a second region 20b, a third region 20c, and a fourth region 20d. Therefore, the first region 20a and the third region 20c are in a diagonal positional relationship with each other, and the second region 20b and the fourth region 20d are also in a diagonal positional relationship with each other. The detector 20 converts the received light into a current signal. Further, it is an advantage of the present invention that the tracking error signal generator 12 and the DPD signal generator 15 can share the detector 20 in calculating the laser irradiation conditions.

  A signal generated by the first region 20a based on the received reflected light is defined as a first current signal. Similarly, current signals corresponding to the second to fourth regions (20b, 20c, 20d) are represented as follows. The second to fourth current signals are assumed.

  In the present embodiment, the detector 20 is divided into four regions as shown in FIG. 2 in order to generate a tracking error signal by the push-pull method. When the dynamic push-pull method is used, a two-divided detector is further arranged on the top and bottom.

  As shown in FIG. 2, the I / V converter 21 includes a first I / V converter 21a, a second I / V converter 21b, a third I / V converter 21c, and a fourth I / V converter 21d. It has.

  The first I / V converter 21a converts the first current signal, which is a current signal of reflected light applied to the first region 20a, into a voltage signal. Hereinafter, the voltage signal converted by the first I / V conversion unit 21a is referred to as a first voltage signal. Then, the first I / V conversion unit 21a outputs the first voltage signal to the tracking error signal generation unit 12 and the DPD signal generation unit 15.

  The second I / V converter 21b converts the second current signal, which is a current signal of reflected light applied to the second region 20b, into a voltage signal. Hereinafter, the voltage signal converted by the second I / V conversion unit 21b is referred to as a second voltage signal. Then, the second I / V conversion unit 21 b outputs the second voltage signal to the tracking error signal generation unit 12 and the DPD signal generation unit 15.

  The third I / V converter 21c converts the third current signal, which is a current signal of reflected light applied to the third region 20c, into a voltage signal. Hereinafter, the voltage signal converted by the third I / V conversion unit 21c is referred to as a third voltage signal. The third I / V conversion unit 21c outputs the third voltage signal to the tracking error signal generation unit 12 and the DPD signal generation unit 15.

  The fourth I / V conversion unit 21d converts the fourth current signal, which is a current signal of reflected light applied to the fourth region 20d, into a voltage signal. Hereinafter, the voltage signal converted by the fourth I / V conversion unit 21d is referred to as a fourth voltage signal. Then, the fourth I / V conversion unit 21d outputs the fourth voltage signal to the tracking error signal generation unit 12 and the DPD signal generation unit 15.

  The tracking error signal generator 12 includes adders 25 and 26 and a subtractor 27 as shown in FIG. The tracking error signal generation unit 12 performs a calculation for generating a tracking error signal using the voltage signal transmitted from the signal detection unit 11, thereby performing tracking by a push-pull method or a differential push-pull method. An error signal is generated.

  The adder 25 adds the first voltage signal input from the first I / V converter 21a and the second voltage signal input from the second I / V converter 21b.

  The adder 26 adds the third voltage signal input from the third I / V converter 21c and the fourth voltage signal input from the fourth I / V converter 21d.

  The subtractor 27 subtracts the sum of the third voltage signal and the fourth voltage signal added by the adder 26 from the sum of the first voltage signal and the second voltage signal added by the adder 25. As a result, the subtracted signal becomes a tracking error signal by the push-pull method. Then, the subtractor 27 outputs the tracking error signal to the DSP 13.

  When the tracking error signal by the differential push-pull method is employed, the two-divided detectors are arranged above and below the four-divided detector 20 in FIG. The tracking error signal generating means is configured to differentiate the differential signals of these detectors from the tracking error signal by the push-pull method.

  As shown in FIG. 1, the DSP 13 has a function of the servo means 17 and a function of the noise calculation unit 18. The DSP 13 performs servo system calculations, and performs noise calculations for the DPD signal described later.

  As shown in FIG. 4, the servo means 17 includes an A / D conversion unit 28, a phase compensation unit 29, and a D / A conversion unit 30. The servo means 17 performs gain adjustment and phase compensation of the focus error signal calculated by a focus error signal generation unit (not shown) and the tracking error signal. In the present embodiment, as shown in FIG. 4, the A / D converter 28 and the D / A converter 30 are provided in the servo means 17, but the present invention is not limited to this. That is, the A / D conversion unit 28 may be provided in the previous stage of the servo means 17, and the D / A conversion section 30 may be provided in the subsequent stage of the servo means 17.

  The A / D converter 28 converts the tracking error signal, which is an analog signal, into a digital signal so that it can be calculated by the DSP. The A / D conversion unit 28 outputs the converted digital signal to the phase compensation unit 29.

  The phase compensation unit 29 performs gain adjustment and phase compensation on the digital signal converted by the A / D conversion unit 28 so that the servo loop does not oscillate. Then, the phase compensation unit 29 outputs the digital signal subjected to gain adjustment and phase compensation to the D / A conversion unit 30.

  The D / A converter 30 converts the digital signal that has been gain-adjusted and phase-compensated by the phase compensator 29 into an analog signal. Then, the D / A converter 30 outputs the analog signal to the driver 14.

  The noise calculation unit 18 calculates the noise variation of the DPD signal input from the DPD signal generation unit 15 described later. Details will be described later.

  As shown in FIG. 1, the driver 14 drives an actuator (not shown) in the optical pickup 3 based on the output from the servo means 17.

  As shown in FIG. 5, the DPD signal generator 15 includes adders 31 and 32, equalizers 33 and 34, binarization processors 35 and 36, a phase comparator 37, low-pass filters 38 and 39, A subtractor 40. The DPD signal generator 15 generates a DPD signal from the voltage signal input from the signal detector 11.

  The adder 31 adds the first voltage signal and the third voltage signal input from the signal detector 11. The adder 31 outputs the added voltage signal to the equalizer 33. Hereinafter, the voltage signals added by the adding unit 31 are referred to as first and third voltage signals.

  The adder 32 adds the second voltage signal and the fourth voltage signal input from the signal detector 11. The adder 32 outputs the added voltage signal to the equalizer 34. Hereinafter, the voltage signals added by the adder 32 are referred to as second and fourth voltage signals.

  The equalizer 33 shapes the first and third voltage signals. Then, the equalizer 33 outputs the waveform-shaped first and third voltage signals to the binarization processing unit 35.

  The equalizer 34 shapes the second and fourth voltage signals. Then, the equalizer 34 outputs the waveform-shaped second and fourth voltage signals to the binarization processing unit 36.

  The binarization processing unit 35 binarizes the first and third voltage signals whose waveforms have been shaped by the equalizer 33. Then, the binarization processing unit 35 outputs the binarized signal to the phase comparison unit 37. Hereinafter, the signal binarized by the binarization processing unit 35 is referred to as a binary signal P.

  The binarization processing unit 36 binarizes the second and fourth voltage signals that have been waveform-shaped by the equalizer 34. Then, the binarization processing unit 36 outputs the binarized signal to the phase comparison unit 37. Hereinafter, the signal binarized by the binarization processing unit 36 is referred to as a binary signal Q.

  The phase comparison unit 37 compares the binary signal P and the binary signal Q to detect a phase error. Specifically, for example, when the phase of the binary signal P is ahead of the phase of the binary signal Q, the phase comparison unit 37 outputs a pulse to the subsequent low-pass filter 38. When the phase of the binary signal P is delayed from the phase of the binary signal Q, the phase comparison unit 37 outputs a pulse to the subsequent low-pass filter 39.

  The low pass filter 38 removes the high frequency component of the pulse output by the phase comparison unit 37. Then, the low-pass filter 38 outputs the pulse from which the high frequency component has been removed to the subtraction unit 40.

  The low-pass filter 39 removes the high-frequency component of the pulse output from the phase comparison unit 37, and the low-pass filter 39 outputs the pulse from which the high-frequency component has been removed to the subtraction unit 40.

  The subtracting unit 40 subtracts the pulse output from the low-pass filter 39 from the pulse output from the low-pass filter 38. As a result, the subtracted signal is set as a DPD signal. The subtractor 40 outputs the DPD signal to the noise calculator 18.

  In the optical disc 1, when the mark is appropriately recorded on the track, the DPD signal coincides with the deviation between the track and the beam spot. Therefore, when a mark is appropriately recorded on the track, the DPD signal can be used as a tracking error signal.

  Further, in the optical disc 1, when the mark is not formed on the track, or the mark is formed but the appropriate mark is not formed because the laser irradiation is not appropriate, the DPD signal includes the track and the beam. The signal does not coincide with the deviation from the spot, and the signal has a lot of noise components (false signal). For this reason, in the present invention for the purpose of optimizing the laser irradiation conditions, the push-pull signal or the differential push-pull signal is generated as the tracking error signal without using the DPD signal as the tracking error signal.

  The reason why the DPD signal becomes a signal having a lot of noise components is due to the binarization processing when the DPD signal is generated. That is, if no mark is formed on the track or an appropriate mark is not formed, the binarization processing units 35 and 36 binarize noise or a signal with a very poor S / N. It becomes. As a result, the binarized noise or a signal with a very poor S / N is input to the phase comparator 37. Therefore, since the phase comparison unit 37 also detects a phase error (false phase difference) using the noise or a signal with a very poor S / N, the DPD signal itself output from the phase comparison unit 37 is also the same. The signal has a lot of noise components.

  The case where the mark is not properly formed on the track is, for example, the case where the mark is not symmetrical in the track direction, or the boundary (edge) between the mark portion and the non-mark portion. The case where is not sharp.

  Here, FIG. 6 shows an image diagram of the mark on the track and the DPD signal. FIGS. 4A to 4C show marks formed on the track under different laser irradiation conditions, and FIGS. 4D to 4E show DPD signals. The DPD signal is generated when tracking control is performed based on a tracking error signal such as a push-pull signal or a differential push-pull signal generated by the tracking error signal generation unit 12.

  FIG. 6A is a diagram showing a predetermined reference for the shape of a recording mark recorded on a track under an appropriate recording condition (laser irradiation condition). As shown in FIG. 6A, the predetermined standard is that the mark is formed without protruding on the track and without changing the mark width between the front and rear of the mark. As shown in FIGS. 6A to 6C, a spot of reflected light reflected by the optical disc 1 is formed on the detector 20, and a “bright” region (FIGS. 6A to 6C) is formed. The white portion of the circle in the detector 20 in c) and the “dark” region (the shaded portion of the circle in the detector 20 in FIGS. 6A to 6C) are formed. The spots are formed in a circular shape regardless of whether or not they are recorded on the track under appropriate recording conditions. However, the ratio of the “bright” area and the “dark” area in the spot varies depending on whether or not the spot is recorded on the track under the proper recording conditions.

  Further, when recording is performed on the track under the proper recording condition, as shown in FIG. 6A, the “bright” area and the “dark” area detected by the detector 20 are detected by the detector 20. And the ratio of the “bright” region to the “dark” region is the ratio of each of the first region 20a, the second region 20b, the third region 20c, and the fourth region 20d. Same in the region. For this reason, when the mark is recorded on the track under an appropriate recording condition, the DPD signal does not contain much noise as shown in FIG. That is, under the proper recording conditions, the DPD signal takes a substantially constant value (usually around 0) if tracking servo is applied.

  On the other hand, FIGS. 6B and 6C are image diagrams of marks formed on the track when the recording conditions are inappropriate. Specifically, when the laser power is insufficient during recording, only a few marks are formed on the track, as shown in FIG. For this reason, the spot on the detector 20 is in a state where the “bright” area occupies a large area and the “dark” area hardly exists. In the spot, as shown in FIG. 6B, the ratio of the “bright” region to the “dark” region is not easily symmetric. In the worst case (when no mark is formed), the “bright” area occupies the entire spot, and the “dark” area disappears. When the laser power at the time of such recording is substantially equal to 0, no mark is formed.

  If the laser power is too large during recording, marks are formed so as to protrude from the track as shown in FIG. Then, the spot has almost no “bright” area, and the “dark” area occupies many areas. Also in this case, as shown in FIG. 6C, the spot in the detector 20 is not symmetrical in the ratio between the “bright” region and the “dark” region. In the worst case (when adjacent marks are connected), the “dark” area occupies the entire spot, and the “bright” area disappears.

  Therefore, when the mark is formed only slightly on the track, or when the mark is formed so as to protrude from the track, the S / N of the detection signal from each element in the signal detection unit 11 is very bad. It becomes. That is, if the laser power is insufficient at the time of recording or the laser power is too high, the DPD signal becomes a signal covered with noise even if tracking servo is applied. In the present invention, the noise component of the DPD signal is used as an index for discrimination between when a mark is appropriately formed on a track and when it is not.

  As described above, when the mark is properly formed, the DPD signal takes a substantially constant value, and noise is superimposed on the DPD signal and the noise component increases as the mark is not properly formed. Is done. For this reason, as a method for measuring the magnitude of noise, the noise component can be calculated by calculating the variation from a certain value of the generated DPD signal. Examples of the variation index include standard deviation and variance. Therefore, by calculating the standard deviation and variance of the DPD signal, it is possible to determine whether or not the noise component of the DPD signal, that is, the mark is properly formed.

  A configuration example of the noise calculation unit 18 that calculates the standard deviation of the DPD signal is shown in FIG. Specifically, the noise calculation unit 18 includes an A / D conversion unit 41, a first multiplication unit 42, a first addition unit 43, a sample number input unit 44, a second multiplication unit 45, and a second addition. A unit 46, a third multiplication unit 47, a subtraction unit 48, an n (n−1) input unit 49, a division unit 50, and a square root calculation unit 51 are provided. The standard deviation formula calculated by the noise calculation unit 18 is shown below.

  Here, n represents the number of samples, that is, the number of samples of the DPD signal. In the present embodiment, n is a predetermined number. For example, if n is set to the power of 2 such as 1024 or 2048, multiplication can be performed by simply shifting the bit by the number of powers when multiplying within the DSP.

  The A / D converter 41 receives the DPD signal generated by the DPD signal generator 15 and converts it into a digital signal. Then, the A / D converter 41 outputs the digital signal to the first multiplier 42 and the second adder 46. Hereinafter, the DPD signal digitally converted by the A / D converter 41 is referred to as a DPD digital signal.

  The first multiplier 42 squares the DPD digital signal. Then, the first multiplier 42 outputs the squared DPD digital signal to the first adder 43.

  The first adder 43 integrates the squared DPD digital signal (hereinafter referred to as a squared DPD digital signal) with another squared DPD digital signal generated by sampling the DPD signal. The integration in the first addition unit 43 is repeated for the number of samples, that is, n times. Then, the first adder 43 outputs the integrated square DPD digital signal to the second multiplier 45.

  The sample number input unit 44 inputs the sample number n to the second multiplication unit 45.

  The second multiplier 45 multiplies the integrated square DPD digital signal by the number of samples n. Then, the second multiplier 45 outputs a square DPD digital signal multiplied by the sample number n to the subtractor 48.

  The second adder 46 integrates the DPD digital signal with another DPD digital signal generated by sampling the DPD signal. The integration in the second addition unit 46 is repeated n times as described above. Then, the second adder 46 outputs the integrated DPD digital signal to the third multiplier 47.

  The third multiplication unit 47 squares the accumulated DPD digital signal. The third multiplier 47 outputs the squared integrated DPD digital signal to the subtractor 48.

  The subtractor 48 subtracts the squared accumulated DPD digital signal input from the third multiplier 47 from the accumulated square DPD digital signal input from the second multiplier 45. The subtracting unit 48 outputs the subtracted signal (hereinafter referred to as a subtracted signal) to the dividing unit 50.

  The n (n−1) input unit 49 inputs a value n (n−1) to the division unit 50.

  The division unit 50 divides the subtraction signal by n (n-1). Then, the dividing unit 50 transmits the divided DPD digital signal to the square root calculating unit 51.

  The square root calculation unit 51 calculates the square root of the divided signal (hereinafter referred to as a division signal). As a result, the standard deviation of the DPD signal expressed by Equation 1 is calculated. The noise calculation unit 18 outputs the standard deviation of the DPD signal to the control unit 16. Hereinafter, the standard deviation of the DPD signal is referred to as an evaluation value.

  The control unit 16 stores the evaluation value calculated by the noise calculation unit 18 in a storage unit (not shown). And the said control part 16 compares the said calculated evaluation value in each laser irradiation conditions. Further, the one having the smallest evaluation value is selected by the comparison. When the evaluation value is selected, the control unit 16 transmits a laser irradiation condition corresponding to the evaluation value to a laser driver (not shown) in the optical pickup 3, and the laser driver sets the laser irradiation condition. Based on the semiconductor laser drive.

  Next, the flow of the laser irradiation condition determination process of the optical disc apparatus according to the present embodiment will be described in detail with reference to the flowchart shown in FIG.

  In the present embodiment, the laser irradiation condition determination process starts when the optical disk is replaced or when the ambient temperature fluctuates greatly. When the process starts, first, in step 1 (hereinafter referred to as S1), the optical pickup 3 reads the irradiation condition recorded in advance on the optical disc 1, and performs test recording from the read irradiation condition. Set the laser irradiation conditions. The parameters for determining the laser irradiation condition are the pulse peak value and the pulse interval already described with reference to FIG. Thereafter, the process proceeds to S2.

  In S2, the optical pickup 3 performs test recording using the set laser irradiation conditions. Here, it is determined in advance how many types of laser irradiation conditions are used for test recording. That is, for example, when the pulse peak value in the laser irradiation condition is set to 5 levels and the pulse interval in the laser irradiation condition is set to 5 levels, the optical disc apparatus performs the 25 types of laser irradiation conditions on the optical disc 1. Perform test recording while changing the laser irradiation location.

  If the number of laser irradiation conditions for performing the test recording is too large, the start-up time of the optical disc apparatus becomes long. In addition, when the number of the laser irradiation conditions is too small, the number of comparison targets in the control unit 16 is reduced, so that a highly accurate evaluation cannot be performed. Therefore, in order to perform a highly accurate evaluation with a very long startup time of the optical disk device, for example, 10 to 20 types of laser irradiation conditions may be performed. However, if the noise component calculation result does not reach the preset value, the irradiation conditions must be changed until the noise component calculation result reaches the predetermined value, and test recording must be performed until the optimum recording condition is found. Don't be. Thereafter, the process proceeds to S3.

  In S3, the optical pickup 3 determines whether or not the test recording is completed. When the test recording is completed, the process proceeds to S4. If the test recording is not completed, the process proceeds to S1, and S1 and S2 are repeated.

  In S4, the optical pickup 3 reproduces the test recording on the optical disc 1. Thereafter, the process proceeds to S5.

  In S5, the DPD signal generation unit 15 generates a DPD signal based on the reproduction. The DPD signal generated by the DPD signal generation unit 15 is a signal that matches the deviation between the track and the beam spot when marks are properly recorded on the track. Then, the DPD signal generation unit 15 outputs the generated DPD signal to the noise calculation unit 18. Thereafter, the process proceeds to S6.

  In S <b> 6, the noise calculation unit 18 calculates the variation of the noise component of the DPD signal input from the DPD signal generation unit 15. The noise component variation of the DPD signal is stored as an evaluation value in a storage unit (not shown). Thereafter, the process proceeds to S7.

  In S7, the optical pickup 3 determines whether or not all test recordings have been reproduced. If the reproduction has been completed, the process proceeds to S8. If the reproduction has not been completed, the process proceeds to S4, and the evaluation value calculation is repeated.

  In S8, the control unit 16 compares the evaluation values. Then, the control unit 16 selects the smallest evaluation value from the evaluation values. Further, in S9, the control unit 16 selects the laser irradiation condition corresponding to the selected evaluation value, that is, the laser irradiation condition with the smallest noise component variation. By the processing of S8 and S9, for example, as shown in FIG. 11, when the evaluation value corresponding to the irradiation condition A is the largest and the evaluation value corresponding to the irradiation condition F is the smallest, as described above, the evaluation value As a result, the irradiation condition F is selected. Thereby, the laser irradiation condition determination process ends.

  In the optical disk apparatus according to the present embodiment, since tracking error signals such as push-pull method and differential push-pull method are used for tracking control, the beam can be stably output regardless of whether or not a mark is recorded on the track. The spot is controlled along the track.

  Next, the way of associating the evaluation value with the laser irradiation condition executed in S9 is as follows.

  For example, at a certain address X on the optical disc 1, recording is performed under the laser irradiation condition N, and the address X is reproduced. As a result, the standard deviation of the DPD signal at that time is set as the evaluation value M. When the evaluation value M is relatively minimum as a result of performing a plurality of laser irradiations and comparing each evaluation value, the control unit 16 indicates that the laser irradiation condition N is the optimal irradiation condition for the optical disc 1. And the laser irradiation condition N is selected.

  As described above, the optical disc apparatus according to the present invention irradiates the optical disc 1 having a track on which information is recorded as a recording mark with a plurality of laser irradiation conditions and irradiates the laser beam, thereby recording marks corresponding to the irradiation conditions. A value reflecting the degree of deviation of the recording mark shape from the predetermined reference in the track from the optical pickup 3 that forms the row on the track and the reflected light when the reproducing light beam is irradiated onto the recording mark row. A noise that calculates a variation of a value that fluctuates in one of the deviation degree signals corresponding to the plurality of laser irradiation conditions for each of the plurality of deviation degree signals. Calculation unit 18 and control unit for selecting the irradiation condition of the laser beam corresponding to the deviation degree signal that minimizes the variation Characterized in that a 6.

  The predetermined standard of the recording mark shape is a recording mark shape when the irradiation condition of the light beam at the time of forming the recording mark is appropriate, and the quality of the reproduction signal when the recording mark is reproduced (for example, S / N) can be said to be a recording mark shape when exceeding the standard. The recording mark that satisfies the predetermined standard is formed, for example, without protruding from the track and without changing the width of the recording mark between the front and rear of the recording mark.

  Further, even in the case of a recording mark row formed on a track under the same irradiation conditions, various noises are superimposed on a signal generated based on the recording mark row. Therefore, the value of the deviation degree signal generated from the reflected light when the recording mark is irradiated with the reproducing light beam fluctuates and varies with the same irradiation condition.

  According to the configuration and the setting method described above, the deviation degree generation unit generates a deviation degree signal, and the calculation unit calculates the variation in the value generated in the deviation degree signal. I know the condition. Further, the calculation means calculates a variation in value generated in one of the deviation degree signals corresponding to the plurality of light beam irradiation conditions for all of the plurality of deviation degree signals, and the control means calculates the variation. The light beam irradiation condition that minimizes is selected.

  Accordingly, it is possible to always set the optimum laser irradiation condition without erroneously adopting the laser recording condition when the data quality is very poor.

  Further, in the optical disc apparatus according to the present invention having the above-described configuration, the DPD signal generation unit 15 generates a DPD signal using the DPD method as the deviation degree signal, and a variation in a value that fluctuates in the DPD signal is generated. It is preferable to calculate.

  By using the DPD method for the deviation signal generation means, the influence of the pit depth on the optical disk can be reduced. That is, the deviation degree signal generation means uses the DPD method to output a tracking error signal even if the pit depth is λ / 4. Therefore, it is not necessary to strictly manage the pit depth. Further, the deviation degree signal generation means can be used as a tracking servo system because the influence of the beam movement on the detector in the optical disk apparatus is small by using the DPD method.

  Further, the DPD signal can be used as a tracking error signal when marks are properly formed on the recording medium. For this reason, if the tracking servo is applied in a state where the marks are properly formed, the DPD signal takes a substantially constant value. However, when the mark is not properly formed, the DPD signal becomes a signal including a lot of noise even when the tracking servo is applied.

  Therefore, according to the above configuration, it can be understood how much noise is included in the DPD signal by calculating a variation in the value generated in the DPD signal. Thereby, since the irradiation state of the laser beam in a plurality of different laser irradiation conditions is relatively known, it is possible to always select and set the optimal laser irradiation condition as compared with the case where other methods are used.

  Further, the DPD signal is generated based on a detector detection signal obtained by dividing the light receiving surface into four points symmetrically. Since the above detector is used for tracking control using a push-pull method, a differential push-pull method, or the like, it can also serve as a detector for generating a DPD signal and a detector for tracking control. Therefore, the deviation signal generation means of the present invention can be configured using the existing configuration, which is advantageous in terms of cost.

  In the optical disk device according to the present invention, in the above configuration, the noise calculation unit 18 preferably calculates the standard deviation of the value of the DPD signal as the variation.

  According to the above configuration, the variation of the DPD signal can be found by obtaining the standard deviation of the DPD signal. Thereby, since the irradiation state of each signal, that is, the laser beam in the laser beam that satisfies each laser irradiation condition is known, the optimum laser irradiation condition can always be selected and set.

  Furthermore, in the optical disk device according to the present invention, in the above configuration, it is preferable that the noise calculation unit 18 calculates the variance of the value of the DPD signal as the variation.

  According to the above configuration, the dispersion of the DPD signal can be found by obtaining the dispersion of the DPD signal, and the calculation amount can be reduced as compared with obtaining the standard deviation. This makes it possible to understand each signal, that is, the laser light irradiation state of the laser light that satisfies each laser irradiation condition, even when the amount of calculation is reduced. Laser irradiation conditions can be selected and set.

  In the optical disk apparatus according to the present invention, in the above-described configuration, it is preferable that the plurality of irradiation conditions are different in pulse peak values of the light beam forming the recording mark.

  According to the above configuration, the plurality of irradiation conditions are determined mainly using the pulse peak value and the pulse interval. For this reason, the DPD signal corresponding to a different pulse peak value can be relatively compared by changing the pulse peak value. Thereby, the optimum pulse peak value can be selected and set.

  Furthermore, in the optical disk apparatus according to the present invention, in the above-described configuration, it is preferable that the plurality of irradiation conditions have different pulse intervals of the light beam forming the recording mark.

  According to the above configuration, the plurality of irradiation conditions are determined mainly using the pulse peak value and the pulse interval. For this reason, it is possible to relatively compare DPD signals corresponding to different pulse intervals by changing the pulse interval. Thereby, an optimal pulse interval can be selected and set.

  Although the noise calculation unit 18 in the present embodiment calculates the standard deviation of the DPD signal, the noise calculation unit 18 may calculate the variance of the DPD signal. The formula for calculating the variance is shown below.

  As apparent from comparison between the above formula (1) and the above formula (2), since the square of the standard deviation is a variance, the noise calculation unit 18 uses the configuration shown in FIG. May be calculated. The difference between the configuration of the noise calculation unit 18 shown in FIG. 7 and the configuration of the noise calculation unit 18 shown in FIG. 8 is that the configuration of the noise calculation unit 18 shown in FIG. The configuration of the noise calculation unit 18 shown in FIG. 8 is that the square root calculation unit 51 is not provided. Accordingly, when the variance of the DPD signal is calculated by comparing the case where the variance of the DPD signal is calculated with the case where the standard deviation of the DPD signal is calculated, it is not necessary to calculate the square root after the division. The amount of calculation can be reduced.

  Further, the optical disc apparatus according to the present invention is not intended to calculate the standard deviation or the variance, but it is only necessary to relatively compare the DPD signals under a plurality of irradiation conditions and select the optimum one. As shown, the division unit 50 in the noise calculation unit 18 shown in FIG. 8 may be further omitted. At this time, an expression realized by the noise calculation unit 18 is shown below.

  When the variation of the DPD signal in the equation (3) is calculated, compared to the case where the standard deviation of the DPD signal in the equation (1) is calculated and the variance of the DPD signal in the equation (2) is calculated. The amount of calculation can be reduced.

  The optical disc apparatus according to the present embodiment irradiates the optical disc 1 with laser light. Examples of the optical disc 1 include CD-R, CD-RW, DVD-R, DVD-RW, DVD + RW, and the like. However, in addition to the above, a BD (Blu-ray Disk) having a larger recording capacity of the optical disk may be used.

  The optical disk apparatus according to the present invention is an apparatus for recording and reproducing data on a rewritable or additionally writable optical disk, and for performing test recording of data under a plurality of different laser irradiation conditions in order to determine the laser irradiation conditions. In the optical disc apparatus that performs the above, a DPD signal generation unit that generates a DPD signal from test-recorded data and a noise component calculation unit that calculates a noise component of the DPD signal that is an output of the DPD signal generation unit may be provided. .

  In the present embodiment, the DPD signal detects only information related to the degree of deviation of the recording mark from the predetermined reference. However, the DPD signal detects a tracking error when the mark is properly formed on the optical disc 1. It can also be used as a signal. In this case, if the tracking servo is applied in a state where the mark is properly formed, the DPD signal has a substantially constant value. However, when the mark is not properly formed, the DPD signal becomes a signal including a lot of noise even when the tracking servo is applied. Therefore, it can be understood how much noise is included in the DPD signal by calculating the variation of the value generated in the DPD signal. Thereby, since the irradiation state of the laser beam under a plurality of types of laser irradiation conditions is relatively known, it is possible to always select and set the optimal laser irradiation conditions as compared with the case where other methods are used.

  The optical disk apparatus according to the present invention is an apparatus for recording and reproducing data on a rewritable or additionally writable optical disk, and test recording of data under a plurality of different laser irradiation conditions in order to determine the laser irradiation conditions In the optical disc apparatus for performing the above, there is provided a DPD signal generating means for generating a DPD signal from the test recorded data, and a noise component calculating means for calculating a noise component of the DPD signal that is an output of the DPD signal generating means. A laser irradiation condition such that the output of the calculation means becomes a predetermined value may be set as the irradiation condition at the time of recording user data.

  Furthermore, the light beam irradiation condition determining method according to the present invention is an apparatus for recording and reproducing data on a rewritable or additionally writable optical disc, and a plurality of different laser irradiation conditions for determining the laser irradiation conditions. In an optical disc apparatus for performing test recording of data, there is provided a DPD signal generating means for generating a DPD signal from the test recorded data and a noise component calculating means for calculating a noise component of the DPD signal which is an output of the DPD signal generating means The laser irradiation condition that the output of the noise component calculation means becomes a predetermined value may be set as the irradiation condition at the time of recording user data.

  Further, in the optical disk device and the light beam irradiation condition determining method according to the present invention, in the above configuration, the noise calculation means may calculate a standard deviation of a DPD signal that is a detection signal from the DPD signal generation means.

  Furthermore, in the optical disk device and the light beam irradiation condition determination method according to the present invention, in the above configuration, the noise calculation unit may calculate a variance of a DPD signal that is a detection signal from the DPD signal generation unit.

  Further, in the optical disk apparatus and the light beam irradiation condition determining method according to the present invention, in the above configuration, the peak value of the laser power applied to the optical disk may be different from the plurality of laser irradiation conditions.

  Further, in the optical disk apparatus and the light beam irradiation condition determining method according to the present invention, in the above configuration, the drive waveform of the laser irradiated on the optical disk may be different from the plurality of laser irradiation conditions.

  The optical disc apparatus and the light beam irradiation condition determining method according to the present invention are the above-described configurations, wherein the conditions when the output of the noise calculating means is the minimum among a plurality of laser irradiation conditions are set at the time of recording user data. Laser irradiation conditions may be set.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

  An optical disc apparatus according to the present invention uses a laser irradiation condition setting method that does not require a new additional circuit and that does not erroneously adopt recording conditions when data quality is very poor. An optical disk device. Therefore, the present invention can be applied to an optical disc apparatus capable of recording, particularly an optical disc recording / reproducing apparatus such as a CD-R, a CD-RW, a DVD-R, a DVD-RW, and a DVD + RW.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, showing an embodiment of the present invention, is a configuration diagram showing a main part of an optical disc apparatus. 1, showing an embodiment of the present invention, is a configuration diagram showing a specific configuration of a signal detection unit in FIG. 1, showing an embodiment of the present invention, is a configuration diagram showing a specific configuration of a tracking error signal generation unit in FIG. 1, showing an embodiment of the present invention, is a functional block diagram illustrating functions of servo means configured in the DSP in FIG. 1, showing an embodiment of the present invention, is a schematic configuration diagram showing a specific configuration of a DPD signal generation unit in FIG. FIG. 4 is a diagram illustrating an embodiment of the present invention and an image diagram of a mark on a track and a DPD signal. (A) is an image diagram when a proper recording mark is formed, and (b) and (c) are image diagrams of a recording mark on a track when recording is performed under an inappropriate laser irradiation condition. . Further, (d) is an image diagram of a DPD signal when an appropriate recording mark is formed on a track, and (e) is an image diagram of a DPD signal when an inappropriate recording mark is formed on a track. is there. 1, showing an embodiment of the present invention, is a schematic configuration diagram showing a specific configuration of a noise calculation unit in FIG. FIG. 3 is a schematic configuration diagram illustrating another specific configuration of the noise calculation unit in FIG. 1 according to the embodiment of the present invention. FIG. 4 is a schematic configuration diagram illustrating still another specific configuration of the noise calculation unit in FIG. 1 according to the embodiment of the present invention. 1 is a flowchart illustrating a method for determining laser irradiation conditions according to an embodiment of the present invention. FIG. 7 is a diagram illustrating an example of a calculation result of an evaluation value when test recording is performed according to an embodiment of the present invention. It is a figure which shows the name of the division area in the light receiving element of the conventional optical disk apparatus. It is a figure which shows the prior art and shows an example of the drive waveform of the laser beam in the case of recording data. (A) is a figure showing the data recorded, (b) is a figure which shows an example of the drive waveform of a laser beam. FIG. 11 is a schematic configuration diagram of an optical disc apparatus that is a conventional optical disc apparatus and performs test writing for setting a drive waveform.

Explanation of symbols

1 optical disk 3 optical pickup (recording means)
11 Signal Detection Unit 12 Tracking Error Signal Generation Unit 13 DSP
14 Driver 15 DPD signal generator (deviation degree signal generator)
16 Control unit (recording means, control means)
17 Servo means 18 Noise calculation part (calculation means)

Claims (7)

Recording means for forming a recording mark row on the track according to each irradiation condition by irradiating the optical beam having a track for recording information as a recording mark with a plurality of irradiation conditions and irradiating a light beam;
Deviation degree signal generation means for generating a deviation degree signal indicating a value reflecting the degree of deviation of the recording mark shape in the track from a predetermined reference from the reflected light when the recording mark row is irradiated with the reproducing light beam When,
Calculating means for calculating a variation of a value that varies in one of the deviation signals corresponding to the plurality of irradiation conditions for each of the plurality of deviation signals;
An optical disc apparatus comprising: control means for selecting an irradiation condition of a light beam corresponding to a deviation degree signal that minimizes the variation.   2. The deviation degree signal generation means generates a DPD signal using the DPD method as the deviation degree signal, and the calculation means calculates a variation in values that fluctuate in the DPD signal. An optical disk device according to the above.   The optical disk apparatus according to claim 1, wherein the calculation unit calculates a standard deviation of the value of the deviation degree signal as the variation.   The optical disk apparatus according to claim 1, wherein the calculation unit calculates a variance of the value of the deviation degree signal as the variation.   2. The optical disc apparatus according to claim 1, wherein the plurality of irradiation conditions are different in a pulse peak value of a light beam forming the recording mark.   2. The optical disc apparatus according to claim 1, wherein the plurality of irradiation conditions are different in a pulse interval of a light beam forming the recording mark. A recording step of forming a recording mark row on the track according to each irradiation condition by irradiating the optical beam having a track for recording information as a recording mark with a plurality of irradiation conditions and irradiating a light beam;
A deviation degree signal generating step for generating a deviation degree signal indicating a value reflecting the degree of deviation of the recording mark shape in the track from a predetermined reference from the reflected light when the recording mark row is irradiated with the reproducing light beam. When,
A calculation step of generating a deviation degree signal corresponding to each of the plurality of irradiation conditions, and calculating a variation of a value varying in one of the deviation degree signals for each of the plurality of deviation degree signals;
A light beam irradiation condition setting method comprising: a control step of selecting an irradiation condition of the light beam corresponding to a deviation degree signal that minimizes the variation.

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