JP2007133958A - Optical disk recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly obtain a target ratio for ROPC even when bending or surface wobbling occurs in an optical disk in an optical disk recorder. <P>SOLUTION: After OPC is executed, in PCA, a signal is written by first recording power. After a first ROPC ratio (ratio 1) is measured based on a return light at this time, a first β value (β1) of this part is measured. Similarly, a second ROPC ratio (ratio 2) and a second β value (β2) are measured. Then, a primary approximate equation regarding the β value and the ROPC ratio is derived from the first ROPC ratio and the first β value and the second ROPC ratio and the second β value, and a target ratio for the ROPC is decided by substituting the approximate equation with a target β value. Thus, irrespective of the result of OPC, a proper ROPC ratio is obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disk recording apparatus that records signals such as video and audio by irradiating a laser beam to an optical disk.

  In recent years, recording optical disks on the market have been manufactured within a certain standard, but detailed specifications differ for each manufacturer, and the optimum recording power for recording differs. Therefore, in an optical disk recording apparatus that records a signal on an optical disk, an optimal value (target value) of recording power is determined by performing a process called OPC (Optimum Power Calibration) before recording a signal such as an image. ing. OPC is a process for determining an optimum value of recording power by writing a signal to a PCA (Power Calibration Area) formed on the inner periphery of the optical disc while changing the recording power and reproducing the signal. .

  However, in an optical disk, the optimum value of the recording power varies in the radial direction of the disk due to the film thickness fluctuation that occurs when the recording film is formed on the disk substrate. In addition, the optimum value of the recording power changes as the temperature of the optical disk rises during signal recording. Therefore, in the optical disc recording apparatus, when a signal such as an image is recorded by irradiating the optical disc with a laser beam, the return light is received, and the ratio (ROPC ratio) between the return light amount and the recording power is the target β during OPC. The recording power is controlled so that the target value (target ratio) obtained based on the value is obtained. Control of the recording power performed in parallel with such recording is called ROPC (Running Optimum Power Calibration).

With respect to ROPC, the following prior art documents are disclosed. For example, in Patent Document 1, a correlation between the ratio of the reflected light intensity from the unrecorded portion and the reflected light intensity from the recorded portion and the β value is obtained, and a desired β value can be obtained based on this correlation. Discloses an optical disc recording apparatus configured to adjust the recording power. Patent Document 2 and Patent Document 3 disclose an optical disk recording apparatus that obtains a recording power for a target β value (target β value) by first-order or second-order approximation from a measurement result of recording power and β value. Has been. Patent Document 4 discloses an optical disk recording apparatus that controls the recording power so that the ratio between the power fluctuation of the laser beam and the fluctuation of the return light amount is constant.
JP 2002-230766 A JP 2002-352426 A JP 2004-171768 A JP 2003-16645 A

  In general, an optical disk composed of a plurality of layers made of different materials may cause uneven warping on the recording surface depending on the structure or storage condition. Further, depending on the chucking state of the optical disk, surface wobbling may occur when the optical disk rotates. Such warpage and surface wobbling of the optical disk are absorbed by the servo mechanism provided in the optical pickup of the optical disk recording apparatus within a certain range, and there is no possibility of causing a problem during normal recording.

  However, when the optical disk is warped or touched, the incident angle of the laser beam with respect to the signal recording surface is not constant, and the OPC results vary. As a result, ROPC cannot be executed at an appropriate target ratio, and even when ROPC is executed by the apparatus disclosed in the above-mentioned patent document, optimum recording power cannot be obtained.

  The present invention has been made to solve the above-described problems, and an optical disc recording apparatus capable of appropriately acquiring a target ratio for ROPC even when the optical disc is warped or run out. The purpose is to provide.

  In order to achieve the above object, an invention according to claim 1 is directed to a disk driving means for rotationally driving an optical disk, and an optical pickup for irradiating a laser beam to the optical disk rotationally driven by the disk driving means to write / read a signal. And a signal processing means for processing the signal read by the optical pickup, a pickup driving means for driving the optical pickup, and a control for controlling the disk driving means and the pickup driving means based on the signal processed by the signal processing means. The optical pickup includes a light emitting element that emits a laser beam, an objective lens that focuses the laser beam emitted from the light emitting element on the recording surface of the optical disc, and a laser beam reflected by the recording surface of the optical disc. A light receiving element that receives light and records signals on an optical disc Before performing OPC (Optimum Power Calibration) in the PCA (Power Calibration Area) of the optical disk and then recording a signal on the optical disk, the light receiving element receives the laser beam reflected by the recording surface of the optical disk. Thus, in the optical disk recording apparatus that executes ROPC (Running Optimum Power Calibration) in parallel with signal writing, the control means executes OPC to obtain a provisional optimum value of recording power, and then the PCA performs the recording. Driving the light emitting element with the first recording power obtained by adding a predetermined value to the provisional optimum value of the power to write a signal, measuring the first ROPC ratio based on the return light received by the light receiving element at that time, Furthermore, by reading the written signal by irradiating a laser beam with a predetermined power, the signal is written with the first recording power. The first β value of the inserted portion is measured, and then a signal is written by driving the light emitting element with the second recording power obtained by subtracting a predetermined value from the provisional optimum value of the recording power. The second ROPC ratio is measured based on the return light received by the element, and further, the second β value of the portion where the signal is written with the first recording power is measured by irradiating the laser beam with a predetermined power, and the first ROPC is measured. By deriving a first-order approximation formula for the β value and the ROPC ratio from the ratio and the first β value, and the second ROPC ratio and the second β value, and substituting the target β value at the time of OPC into the approximation formula, the target ratio in ROPC is calculated. To decide.

  According to a second aspect of the present invention, there is provided a disk driving means for rotationally driving an optical disk, an optical pickup for irradiating a laser beam to the optical disk rotated by the disk driving means to write / read a signal, and the optical pickup for reading. An optical pickup comprising: a signal processing means for processing the received signal; a pickup driving means for driving the optical pickup; and a control means for controlling the disk driving means and the pickup driving means based on the signal processed by the signal processing means. Includes a light emitting element that emits a laser beam, an objective lens that focuses the laser beam emitted from the light emitting element on the recording surface of the optical disc, and a light receiving element that receives the laser beam reflected by the recording surface of the optical disc. Before recording a signal on the optical disc, the optical disc PC Even when OPC (Optimum Power Calibration) is executed in the (Power Calibration Area) and then a signal is recorded on the optical disc, the signal is written by receiving the laser beam reflected by the recording surface of the optical disc by the light receiving element. In the optical disc recording apparatus that executes ROPC (Running Optimum Power Calibration) in parallel with the control unit, the control means writes the signal by varying the recording power, and measures the ROPC ratio based on the return light received by the light receiving element, Furthermore, by reading a signal written by irradiating a laser beam of a predetermined power, the β value of the portion where the signal is written by varying the recording power is measured, and the β value is calculated from each ROPC ratio and each β value. By deriving an approximate expression for the ROPC ratio and substituting the target β value during OPC into the approximate expression It is intended to determine the target ratio of ROPC.

  According to the first aspect of the present invention, after executing the OPC, in the PCA, the signal is written by changing the recording power, the ROPC ratio is measured based on the amount of the return light, and the β value of the writing portion is calculated. Measure each. Since an approximate expression for the β value and the ROPC ratio is derived from each ROPC ratio and each β value measured in this way, and the target β value at the time of OPC is substituted into the approximate expression, the target ratio in ROPC is determined. An appropriate ROPC ratio can be obtained without being influenced by the result of OPC. Thereby, it is possible to always write a signal to the optical disc with the optimum recording power.

  Further, when deriving an approximate expression related to β values and ROPC ratios, it is necessary to sample a plurality of ROPC ratios and β values corresponding to them. According to the present invention, first, a temporary optimum value of recording power is obtained by executing OPC, and a signal is written with a first recording power obtained by adding a predetermined value to the provisional optimum value of the recording power. To measure the first ROPC ratio and the corresponding first β value. Similarly, the first ROPC ratio and the corresponding second β value are measured by writing a signal with the second recording power obtained by subtracting a predetermined value from the provisional optimum value of the recording power. As a result, the relationship between the β value and the ROPC ratio can be approximated in a region including the provisional optimum value of the recording power, and the reliability of the approximate expression can be improved. In addition, since a first-order approximation expression is derived between two points, the ROPC ratio can be calculated quickly, and the operation of recording a signal such as a video can be quickly performed.

  According to the second aspect of the present invention, the signal is written by changing the recording power, the ROPC ratio is measured based on the return light amount, and the β value of the written portion is measured. Since an approximate expression for the β value and the ROPC ratio is derived from each ROPC ratio and each β value measured in this way, and the target β value at the time of OPC is substituted into the approximate expression, the target ratio in ROPC is determined. An appropriate ROPC ratio can be obtained without being influenced by the result of OPC. Thereby, it is possible to always write a signal to the optical disc with the optimum recording power.

  An optical disk recording apparatus according to the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of an optical disk recording apparatus. An optical disk recording apparatus 1 includes a spindle motor (disk drive means) 2 that rotationally drives an optical disk D, an optical pickup 3 that irradiates a rotating optical disk D with a laser beam L and writes / reads a signal, and an optical pickup 3 Controls a signal processing unit (signal processing unit) 4 for processing a signal read by the driver, a driving unit (disk driving unit, pickup driving unit) 5 for applying a driving voltage to the spindle motor 2 and the optical pickup 3, and control of each part of the apparatus. It is configured by a control unit (control means) 6 and the like. For example, the control unit 6 controls the spindle motor 2 and the optical pickup 3 via the drive unit 5 based on the signal processed by the signal processing unit 4.

  The optical pickup 3 includes a laser diode (light emitting element) 11 that emits a laser beam, a collimator lens 13 that collimates the laser beam emitted from the laser diode 11, and a laser beam that has passed through the collimator lens 13. The objective lens 14 for condensing on the recording surface and the laser beam emitted from the laser diode 11 are transmitted toward the collimator lens 13, reflected by the recording surface of the optical disc D, and transmitted through the objective lens 14 and the collimator lens 13. The beam splitter 12 reflects the laser beam toward the photodiode 15, and the photodiode (light receiving element) 15 receives the laser beam reflected by the beam splitter 12.

  As described above, in general, an optical disc recording apparatus is configured to perform OPC (Optimum Power Calibration) in a PCA (Power Calibration Area) of an optical disc before recording a signal on the optical disc in order to improve signal writing quality on the optical disc. Then, even when a signal is recorded on the optical disk, the laser beam reflected by the recording surface of the optical disk (returned light) is received by the light receiving element, so that the ROPC is performed in parallel with the signal writing. (Running Optimum Power Calibration).

  ROPC controls the recording power so that the ratio (ratio) between the return light quantity and the recording power becomes the target value (target ratio) of the ROPC ratio obtained based on the target β value specific to each medium of the optical disc. It is made by. Therefore, in an optical disc recording apparatus, obtaining an appropriate target ratio is important in executing ROPC.

  FIG. 2 shows the recording power and β value (average value (indicated by black dots in the figure)) obtained by an experiment in which the recording power of the laser diode 11 is gradually increased from W1 to W4 to record a signal on the PCA of the optical disk D. ) And variations (indicated by horizontal lines above and below the black dots in the figure)). The β value can be obtained by irradiating a laser beam having a predetermined power onto a portion where the signal is written, reading the written signal, and performing a predetermined calculation from the read signal. From FIG. 2, there is a slight variation in the β value measured for each recording power, and when the recording power is gradually increased from W1 to W4, the average value of β values for each recording power is obtained. It can be seen that also increases linearly.

  On the other hand, FIG. 3 shows the recording power and ROPC ratio (average value (indicated by black dots in the figure) and variation (indicated by horizontal lines above and below the black dots)) obtained by the same experiment as described above. Showing the relationship. The ROPC ratio measures the return light received by the photodiode 15 when the signal is recorded on the PCA of the optical disc D by gradually increasing the recording power of the laser diode 11 from W1 to W4. And can be obtained by calculating the ratio. It can be seen from FIG. 3 that there is a slight variation in the return light amount ROPC ratio measured for each recording power, and that there is a slight variation in the ROPC ratio accordingly. It can also be seen that when the recording power is increased stepwise from W1 to W4, the average value of the ROPC ratio for each recording power decreases linearly.

  FIG. 4 shows the relationship between the β value obtained from the experimental results shown in FIGS. 2 and 3 and the ROPC ratio. The relationship between the β value and the ROPC ratio can be approximated by a first-order approximation. This approximate expression can be derived by erasing the recording power from the linear approximate expression between the recording power and the β value in FIG. 2 and the linear approximate expression between the recording power and the ROPC ratio in FIG. . In the present embodiment, in order to simplify the processing, a first-order approximation expression indicating the relationship between the β value and the ROPC ratio is derived by executing processing described later.

  FIG. 5 shows processing executed by the control unit 6 in order to acquire the ROPC target ratio. The control unit 6 first obtains a provisional optimum value of the recording power by executing OPC (# 1). The provisional optimum value is affected by the surface shake of the optical disc D and may vary slightly, so that it is treated as a provisional value. Next, the control unit 6 calculates a first recording power by adding a predetermined value to the provisional optimum value of the recording power. Then, the laser diode 11 is driven with this first recording power to write a signal, and the first ROPC ratio (ratio 1 in FIG. 4) is measured based on the return light received by the photodiode 15 (# 2). Further, by driving the laser diode 11 with a predetermined power and irradiating the laser beam, the first β value (β1 in FIG. 4) of the portion where the signal is written with the first recording power is measured (# 3). Thereafter, the second recording power is calculated by subtracting a predetermined value from the provisional optimum value of the recording power. Then, as described above, a signal is written with the second recording power, the second ROPC ratio (ratio 2 in FIG. 4) is measured based on the return light at that time (# 4 in FIG. 4), and the signal with the second recording power. The second β value (β2 in FIG. 4) of the portion in which is written is measured (# 5). Then, a first-order approximate expression relating to the β value and the ROPC ratio is derived from the first ROPC ratio and the first β value acquired by the processes of # 2 to # 5, and the second ROPC ratio and the second β value (# 6). The target ratio in ROPC is determined by substituting the target β value into the first-order approximate expression thus derived (# 7). The power of the laser diode 11 at # 3 and # 5 may be equal to the power at the time of reading a normal signal.

  FIG. 6 shows the relationship between the results obtained by conducting an experiment for obtaining the ROPC target ratio a plurality of times for each recording power W1, W2, and W3. In the figure, the ROPC target ratio determined by executing the above-described processing for each recording power by the optical disc recording apparatus 1 of the present embodiment is indicated by black dots and solid lines. On the other hand, the ROPC target ratio determined for each recording power by the conventional optical disk recording apparatus is indicated by white dots and broken lines. In the conventional optical disk recording apparatus, the variation of the ROPC target ratio for each recording power is large, and the value of the ROPC target ratio increases as the recording power is increased to W1, W2, and W3. On the other hand, according to the optical disk recording apparatus 1 of the present embodiment, the variation of the ROPC target ratio for each recording power is small, and even if the recording power is increased to W1, W2, and W3, the value of the ROPC target ratio is It is almost constant.

  FIG. 7 shows the frequency distribution of the ROPC target ratio in the above experiment. In the figure, the solid line indicates the frequency distribution by the optical disk recording apparatus 1 of the present embodiment, and the wavy line indicates the frequency distribution by the conventional optical disk recording apparatus. As can be seen from the figure, the ROPC target ratio acquired by the conventional optical disk recording apparatus has a large variation and is unstable, whereas the ROPC target ratio acquired by the optical disk recording apparatus 1 of the present embodiment. Has a small variation and is stable.

  As described above, according to the optical disc recording apparatus 1 of the present embodiment, after executing OPC, the PCA changes the recording power and writes a signal, and measures the ROPC ratio based on the return light amount. , And measure the β value of the written portion. Since the approximate expression regarding the β value and the ROPC ratio is derived from the plurality of ROPC ratios and β values measured in this way, and the target β value at the time of OPC is substituted into the approximate expression, the target ratio in ROPC is determined. An appropriate ROPC ratio can be obtained without being influenced by the result of OPC. Thereby, it is possible to always write a signal to the optical disc D with the optimum recording power.

  Further, when deriving an approximate expression related to β values and ROPC ratios, it is necessary to sample a plurality of ROPC ratios and β values corresponding to them. According to the optical disk recording apparatus 1, first, OPC is executed to obtain a provisional optimum value of recording power, and a signal is output with the first recording power obtained by adding a predetermined value to the provisional optimum value of the recording power. By writing, the first ROPC ratio and the corresponding first β value are measured. Similarly, the first ROPC ratio and the corresponding second β value are measured by writing a signal with the second recording power obtained by subtracting a predetermined value from the provisional optimum value of the recording power. As a result, the relationship between the β value and the ROPC ratio can be approximated in a region including the provisional optimum value of the recording power, and the reliability of the approximate expression can be improved. In addition, since a first-order approximation expression is derived between two points, the ROPC ratio can be calculated quickly, and the operation of recording a signal such as a video can be quickly performed.

  The present invention is not limited to the configuration of the above embodiment, and at least the recording power is varied to measure a plurality of pairs of ROPC ratios and β values, and an approximate expression relating to the β value and the ROPC ratio from the measured values of the plurality of pairs. And the target ratio in ROPC may be determined by substituting the target β value into the approximate expression. Therefore, for example, when the approximate expression is derived, if more than three corresponding pairs of ROPC ratio and β value are used, a more appropriate ROPC ratio can be acquired.

1 is a diagram showing a schematic configuration of an optical disc recording apparatus according to an embodiment of the present invention. The figure which shows the relationship between the recording power of the laser diode obtained by experiment, and (beta) value. The figure which shows the relationship between the recording power obtained by experiment, and a ROPC ratio. The figure which shows the relationship between (beta) value obtained from the experimental result of FIG.2 and FIG.3, and a ROPC ratio, and a ROPC target ratio. The flowchart which shows the process which a control part performs in order to acquire a ROPC target ratio. The figure which shows the relationship between the recording power obtained by experiment, and a ROPC target ratio. The figure which shows the frequency distribution of the ROPC target ratio in experiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk recording device 2 Spindle motor (disk drive means)
3 Optical pickup 4 Signal processing unit (signal processing means)
5 Drive unit (disk drive means, optical pickup drive means)
6 Control unit (control means)
11 Laser diode (light emitting element)
14 Objective lens 15 Photodiode (light receiving element)

Claims (2)

Disk drive means for rotating the optical disk, an optical pickup for writing / reading a signal by irradiating the optical disk rotated by the disk drive means with a laser beam, and signal processing for processing the signal read by the optical pickup Means, a pickup driving means for driving the optical pickup, and a control means for controlling the disk driving means and the pickup driving means based on the signal processed by the signal processing means,
The optical pickup includes a light emitting element that emits a laser beam, an objective lens that focuses the laser beam emitted from the light emitting element on a recording surface of the optical disc, and a light receiving device that receives the laser beam reflected by the recording surface of the optical disc. Having an element,
Before recording a signal on the optical disc, OPC (Optimum Power Calibration) is executed in the PCA (Power Calibration Area) of the optical disc, and when the signal is subsequently recorded on the optical disc, the laser beam reflected by the recording surface of the optical disc In the optical disk recording apparatus that performs ROPC (Running Optimum Power Calibration) in parallel with signal writing by receiving light by the light receiving element,
The control means includes
After the OPC is executed and the provisional optimum value of the recording power is acquired, the light emitting element is driven by the first recording power obtained by adding a predetermined value to the provisional optimum value of the recording power in the PCA. The first recording power is read by measuring the first ROPC ratio based on the return light received by the light receiving element at that time, and reading the written signal by irradiating a laser beam with a predetermined power. Measure the first β value of the part where the signal was written in
Thereafter, the light emitting element is driven with the second recording power obtained by subtracting a predetermined value from the provisional optimum value of the recording power, and a signal is written, and then the light receiving element receives the first light based on the return light received by the light receiving element. 2 ROPC ratio is measured, and further, by irradiating a laser beam with a predetermined power, the second β value of the portion where the signal is written with the first recording power is measured,
Deriving a first-order approximation formula for the β value and the ROPC ratio from the first ROPC ratio and the first β value, and the second ROPC ratio and the second β value,
An optical disc recording apparatus, wherein a target ratio in ROPC is determined by substituting a target β value at the time of OPC into the approximate expression. Disk drive means for rotating the optical disk, an optical pickup for writing / reading a signal by irradiating the optical disk rotated by the disk drive means with a laser beam, and signal processing for processing the signal read by the optical pickup Means, a pickup driving means for driving the optical pickup, and a control means for controlling the disk driving means and the pickup driving means based on the signal processed by the signal processing means,
The optical pickup includes a light emitting element that emits a laser beam, an objective lens that focuses the laser beam emitted from the light emitting element on a recording surface of the optical disc, and a light receiving device that receives the laser beam reflected by the recording surface of the optical disc. Having an element,
Before recording a signal on the optical disc, OPC (Optimum Power Calibration) is executed in the PCA (Power Calibration Area) of the optical disc, and then when the signal is recorded on the optical disc, the laser beam reflected by the recording surface of the optical disc In an optical disc recording apparatus that performs ROPC (Running Optimum Power Calibration) in parallel with signal writing by receiving light by the light receiving element,
The control means includes
The recording power is changed, the signal is written, the ROPC ratio is measured based on the return light received by the light receiving element, and the written signal is read by irradiating a laser beam with a predetermined power. Measure the β value of the part where the signal was written by varying the power,
Deriving an approximate expression for β value and ROPC ratio from each ROPC ratio and each β value,
An optical disc recording apparatus, wherein a target ratio in ROPC is determined by substituting a target β value at the time of OPC into the approximate expression.

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