JP2008077714A - Optical disk apparatus, and method for controlling recording power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk apparatus and a method for controlling recording power which secure the quality in recording data to an optical disk. <P>SOLUTION: The optical disk apparatus reproduces the data recorded in the optical disk, obtains a value β showing the asymmetry of an amplitude based on the reproduced data, calculates the inverse number of the change ratio of the value β to the recording power as a correction coefficient based on the plurality of values β, calculates a corrected recording power using the correction coefficient and corrects the recording power based on the calculated corrected recording power. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus and a recording power control method, and is particularly suitable for application to an optical disc apparatus that requires high laser power.

  Conventionally, a method called walking OPC (Optimum Power Control) has been proposed as a recording power control method in an optical disk apparatus compatible with high-speed recording (see Patent Document 1 and Patent Document 2). The walking OPC method is a method in which recording is stopped at regular intervals or every predetermined time to reproduce the recording end portion, and the recording quality of the data at the recording end portion is evaluated, and the recording power is corrected based on the evaluation result. In recent years, it has been widely used because high recording quality that guarantees reproduction compatibility can be ensured.

  In the walking OPC method, a parameter called a β value that indicates non-target amplitude is usually used as an index of recording quality. In the walking OPC method, a β value that should be a target set in advance (every time is referred to as a target β value) and a recording end point at that time are reproduced at regular intervals or at regular time intervals. The obtained β value (hereinafter referred to as “measured β value” where appropriate) is compared, and the recording power is corrected based on the difference between these values.

  The β value changes almost uniformly according to the change in recording power. For this reason, by using the β value as an index of recording quality, it goes without saying that the recording system always has a constant recording power as in the CLV (Constant Linear Velocity) system, as in the CAV (Constant Linear Velocity) system, Even in the case of a recording method in which the recording speed increases toward the outer peripheral side of the optical disc and the recording power increases with this, the relationship between the difference amount between the target β value and the measured β value and the correction amount of the recording power Can be uniform.

  However, the change ratio of the β value with respect to the recording power differs for each type of optical disc. For this reason, an optical disc apparatus adopting such a walking OPC system holds a target β value for each type of optical disc, and uses a corresponding target β value according to the type of optical disc loaded at that time. Has been built.

  In the above-mentioned patent document 1, the β power and the reflectivity for each vendor and each recording linear velocity are stored in the flash memory in the optical disc apparatus for the high accuracy of the recording power correction at the high speed recording for the purpose of ensuring the recording quality. A method is disclosed in which a coefficient table is stored and a β value and reflectance obtained at the time of trial writing are combined to be used as an index of recording quality.

In Patent Document 2, the β value at each recording power is measured at the time of trial writing, and the amount of change in recording power with respect to the amount of change in β value in the vicinity of a predetermined β value is calculated. A walking OPC method has been proposed in which the effect of the stray light on the β value is removed.
Japanese Patent Laid-Open No. 2005-116027 JP 2006-120281 A

  By the way, in recent years, an optical disc apparatus corresponding to three types of optical discs of BD (Blu-ray Disc), DVD (Digital Versatile Disc), and CD (Compact Disc) has been proposed. In addition, a focus lens that focuses laser light of each wavelength on an information recording surface of an optical disc is being made into one lens. In this case, the focus lens has a property that the light transmittance changes depending on the temperature.

  On the other hand, in the conventional recording power control by the APC (Auto Power Control) method, the control is performed by monitoring the amount of laser light before the focus lens.

  Therefore, when the recording power control in the walking OPC method is performed by the conventional APC method, the laser light amount that passes through the focus lens and is focused on the optical disk is affected by the environmental temperature. And a difference between the amount of laser light actually incident on the optical disc. As a result, such a conventional optical disc apparatus has a problem that the recording power cannot be accurately controlled and the recording quality at the time of data recording on the optical disc cannot be secured.

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose an optical disc apparatus and a recording power control method capable of ensuring recording quality when data is recorded on an optical disc.

  In order to solve such a problem, in the present invention, when data is recorded on an optical disc, the recording quality of the data on the optical disc is periodically evaluated, and the recording power is controlled based on the evaluation result. A reproducing unit that reproduces the recorded data, a β value obtaining unit that obtains a β value representing non-target amplitude based on the data reproduced by the reproducing unit, and the obtained β A target recording power calculation unit that calculates a correction coefficient that is a conversion coefficient from a β value to a recording power based on the value and calculates a corrected recording power to be a target using the correction coefficient; and the target A recording power correction unit that corrects the recording power based on the corrected recording power calculated by the recording power calculation unit. To.

  Also, in the present invention, when recording data on the optical disc, the recording quality of the data on the optical disc is periodically evaluated, and the recording power control method for controlling the recording power based on the evaluation result is recorded on the optical disc. A first step of reproducing the data, a second step of obtaining a β value representing non-amplitude of amplitude based on the reproduced data, and β based on the obtained β values for a plurality of times A third step of calculating a correction coefficient consisting of a conversion coefficient from a value to a recording power and calculating a corrected recording power to be targeted using the correction coefficient; and calculating and calculating the corrected recording power And a fourth step of correcting the recording power based on the fourth step.

  ADVANTAGE OF THE INVENTION According to this invention, the optical disk apparatus and recording power control method which can ensure the recording quality at the time of the data recording on an optical disk are realizable.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Configuration of Optical Disc Device According to this Embodiment FIG. 1 shows an optical disc device 1 according to this embodiment. This optical disc apparatus 1 is compatible with three types of optical discs 2 of BD, DVD, and CD, and records data on these optical discs 2 or data recorded on these optical discs 2 in response to a request from the host computer 3. Has been made to play.

  In practice, in this optical disk apparatus 1, the motor drive unit 10 drives the spindle motor 11 under the control of the digital signal processor 12, so that the optical disk 2 loaded in a predetermined state is stored in the optical disk 2. It is rotated in a rotating state according to the recording method (for example, CAV method or CLV method).

  In the optical disc apparatus 1, various commands transmitted from the host computer unit 3 are given to the microcomputer unit 13 via the interface unit 12.

  The microcomputer unit 13 includes a memory 13A in which a control program is stored, and necessary control processing and arithmetic processing are performed according to commands given from the host computer 3 and various information given from the digital signal processor 14. Execute.

  For example, when a recording command is given from the host computer 3, the microcomputer unit 13 controls the interface unit 12, and thereafter records data to be recorded transmitted from the host computer 3 to the digital signal processor 14. To send.

  The digital signal processor 14 performs predetermined signal processing including modulation processing on the data to be recorded provided via the interface unit 13, and sends the recording signal thus obtained to the laser driving unit 15 as a driving signal. To do.

  The laser driver 15 blinks and drives a laser diode (not shown) in the optical pickup 16 based on a drive signal given from the digital signal processor 14. As a result, the blinking pattern according to the content of the drive signal (recording signal) and the laser light L1 having a light amount according to the signal level of the drive signal are emitted from the laser diode, and this laser light LI is illustrated in the optical pickup 16. The light is focused on the recording surface 2A of the optical disc 2 through a focus lens that is not. Thereby, data to be recorded is recorded on the optical disc 2.

  The reflected light L2 of the laser light L1 on the optical disk 2 is photoelectrically converted by a photodetector (not shown) in the optical pickup 16. In addition, an RF (Radio Frequency) signal obtained by this photoelectric conversion is digitally converted by the analog / digital conversion unit 17 and supplied to the digital signal processor 14 as a digital RF signal.

  The digital signal processor 14 generates various control signals such as a focus error signal, a tracking error signal, and a rotation control signal based on the supplied digital RF signal. Thus, a biaxial actuator (not shown) in the optical pickup 16 is controlled based on these focus error signal and tracking error signal, thereby performing focus control and tracking control. The rotation control signal is given to the motor drive unit 10, and the rotation control of the spindle motor 11 is performed by the motor drive unit 10 based on this rotation control signal.

  Further, a part of the laser light L1 emitted from the laser diode in the optical pickup 16 is split before entering the focus lens, and is photoelectrically converted by an APC control photodetector (not shown) in the optical pickup 16. The RF signal obtained by the photoelectric conversion is digitally converted by the analog / digital converter 17 and then applied to the digital signal processor 14 as a digital RF signal.

  Thus, the digital signal processor 14 uses the laser signal so that the recording power becomes a target recording power preset for APC control (hereinafter referred to as target recording power) based on the digital RF signal. The signal level of the drive signal sent to the drive unit 15 is controlled.

  On the other hand, when receiving a reproduction command from the host computer 3 via the interface unit 12, the microcomputer unit 13 controls the digital signal processor 14 to send a predetermined control signal to the laser driving unit 15.

  The laser drive unit 15 drives the laser diode in the optical pickup 16 to light at a predetermined voltage based on the supplied control signal. As a result, laser light with a predetermined power is emitted from the laser diode, and this laser light is condensed on the recording surface 2A of the optical disc 2 through the focus lens.

  The reflected light L2 of the laser light L1 on the optical disk 2 is photoelectrically converted by the photodetector in the optical pickup 16, and the RF signal thus obtained is digitally converted by the analog / digital converter 17 and converted into a digital signal as a digital RF signal. Provided to the processor 14

  The digital signal processor 14 subjects the supplied digital RF signal to reproduction signal processing such as demodulation processing, and sends the reproduced data thus obtained to the host computer 3 via the interface unit 12. .

  The digital signal processor 14 generates various control signals such as a focus error signal, a tracking error signal, and a rotation control signal based on the digital RF signal in the same manner as when recording data. Thus, based on the focus error signal, tracking error signal, and rotation control signal, focus control, tracking control, and rotation control of the spindle motor 11 are performed in the same manner as during data recording.

(2) Recording power control method in the optical disc apparatus of the present embodiment Next, a recording power control method employed in the optical disc apparatus 1 will be described.

In the walking OPC method, in order to control the recording power while acquiring the measured β value, as shown in FIG. 2A, some measured β values (β ₁ , β ₂ ,. )), The relationship between the recording power (P ₁ , P ₂ ,...) And the measured β value (β ₁ , β ₂ ,...) In the optical disc 2 used at that time can be detected. it can. Specifically, the change ratio of the measured β value with respect to the recording power on the optical disc 2, which is the slope of the line segment K in FIG.

  Therefore, in the optical disc apparatus 1 according to the present embodiment, the walking OPC method is adopted as the recording power control method, and the relationship between the measured β value obtained by the recording power control by the walking OPC method and the recording power at that time. Based on the above, the change ratio (slope) A of the measured β value with respect to the recording power is calculated.

のようにして、記録パワーのウォーキングＯＰＣパワーアップレートＲ_UPを算出し、算出したウォーキングＯＰＣパワーアップレートＲ_UPを現在の目標記録パワーに乗算するようにして、補正後の新たなＡＰＣ制御の目標記録パワーを算出する。なお、（１）式において、Ｒ_UP′は、前回算出したウォーキングＯＰＣパワーアップレートを示す。 In the optical disc apparatus 1, the reciprocal (1 / A) of the change ratio A is used as a correction coefficient, and

As described above, the walking OPC power up rate R _UP of the recording power is calculated, and the current target recording power is multiplied by the calculated walking OPC power up rate R _UP so that a new target of APC control after correction is performed. The recording power is calculated. In the equation (1), R _UP ′ indicates the walking OPC power up rate calculated last time.

Here, the walking OPC power up rate R _UP is a ratio of increasing / decreasing the reference recording power based on the recording power immediately after the correction (hereinafter referred to as the reference recording power) corrected by the trial writing. Say. For example, walking OPC when the correction coefficient (1 / A) obtained when evaluating the first recording quality is 1 and the difference between the target β value and the measured β value (target β value−measured β value) is 1. The power-up rate R _UP is 1 [%]. Accordingly, in this case, the recording power obtained by increasing the reference recording power by 1 [%] is the current recording power (the recording power until the next recording quality is evaluated).

  In the optical disc apparatus 1, a storage table 20 as shown in FIG. 3 is stored in the memory 13A of the microcomputer unit 13 as means for performing such recording power control.

  This storage table 20 shows the target β value and the recording power (target recording) when the recording speed is set to 1 × speed, 2 × speed, 4 × speed, etc. for each optical disc 2 sold by each optical disc manufacturer. It is a table that summarizes (power).

  The optical disc apparatus 1 reads out the target β value corresponding to the type of the optical disc 2 loaded at that time and the recording speed at that time among the target β values stored in the storage table 20, Used for the calculation of equation (1).

  However, if the recording conditions change due to environmental changes, such as the transmittance of the focus lens changing due to the temperature rise of the focus lens, even if recording is performed with the same recording power as shown in FIG. The measured β value obtained varies greatly.

Therefore, in the optical disc apparatus 1 of the present embodiment, when the value of the measured β value obtained when recording is performed with the same recording power as the previous time is significantly different from the previously measured β value, this time The current walking OPC power up rate R _UP is calculated by the equation (1) using a predetermined fixed correction coefficient without using the obtained measured β value.

  Here, in the case of the optical disc apparatus 1 according to the present embodiment, such recording power control is performed under the control of the microcomputer unit 13 based on the control program stored in the memory 13A of the microcomputer unit 13. Executed.

  FIG. 5 is a flowchart showing the processing contents of the microcomputer unit 13 relating to such recording power control.

  When a recording command is given from the host computer 3, the microcomputer unit 13 starts the recording power control process shown in FIG. 5 (SP0), and first controls the digital signal processor 14 and a seek motor (not shown). Then, a trial writing is performed in a predetermined area on the optical disc 2, and the β value at that time is measured. Then, the recording power is corrected based on the measured β value obtained at this time (SP1). Such a β value measurement method and recording power correction method will be described later (see step SP4 and step SP10).

  Subsequently, the microcomputer unit 13 drives the seek motor and the digital signal processor 14 to move the optical pickup 16 to the recording start position on the optical disc 2 obtained based on the recording command, and starts the recording. Recording of data to be recorded is started from the position (SP2).

  Next, the microcomputer unit 13 determines whether or not a certain time (or a certain interval) has elapsed since the start of data recording (SP3). If a negative result is obtained, the microcomputer unit 13 returns to step SP2 to return the data to the optical disk. Let the recording continue.

  If the microcomputer unit 13 obtains a positive result in step SP3 after a certain time (or a certain interval) has elapsed since the start of data recording, the microcomputer unit 13 measures the β value at that time (SP4).

  Specifically, the microcomputer unit 13 controls the digital signal processor 14 and the seek motor to stop recording data to be recorded on the optical disc 2 and reproduce the recording end unit. The RF signal obtained at this time is given to the digital signal processor 14 via the digital converter 17.

のようにしてそのときのβ値（測定β値）を算出する。なお、この（２）式において、ａ１は再生信号の最大レベルを示し、ａ２は再生信号の最小レベルを示す。またディジタル・シグナル・プロセッサ１４は、このようにして得られたβ値をマイクロコンピュータ部１３に送出する。 The digital signal processor 14 performs predetermined signal processing such as demodulation processing on the supplied digital RF signal, and on the basis of the reproduced signal thus obtained,

The β value at that time (measured β value) is calculated as follows. In equation (2), a1 represents the maximum level of the reproduction signal, and a2 represents the minimum level of the reproduction signal. The digital signal processor 14 sends the β value thus obtained to the microcomputer unit 13.

Thereafter, the microcomputer unit 13 determines whether or not the number of times the β value is measured is equal to or greater than a predetermined number of times (for example, 4 to 6 times) (SP5). If the microcomputer unit 13 obtains a negative result in this determination, it uses the fixed correction coefficient (1 / A) prepared in advance to calculate the walking OPC power up rate R _{UP according} to equation (1) (SP9). ).

Further, the microcomputer unit 13 calculates the corrected recording power by multiplying the calculated walking OPC power up rate R _UP by the current recording power, and digitally uses this recording power as a new target recording power for APC control. Set in the signal processor 14 (SP10). As a result, the APC control is performed by the digital signal processor 14 so that the recording power matches the target recording power.

  On the other hand, when the microcomputer unit 13 obtains a positive result in the determination at step SP5, it determines whether or not the current recording power is the same as the recording power when the previous β value was measured (SP6).

  If the microcomputer unit 13 obtains a negative result in this determination, whether or not the β value acquired this time is the same as or substantially the same as the previously acquired β value (for example, whether or not it is within an error range of about several percent). (SP7).

If the microcomputer unit 13 obtains a negative result in this determination, it calculates the walking OPC power up rate R _UP by the equation (1) using the fixed correction coefficient (1 / A described above) ( SP9), and calculates the recording power corrected based on the calculated walking OPC power uprate R _uP, set the digital signal processor 14 so as target recording power of a new APC control (SP10).

In contrast, if the microcomputer unit 13 obtains a positive result in the determination of step SP6 or step SP7, the microcomputer 13 obtains the measurement β value obtained this time and the previous time to obtain the correction coefficient most suitable for the current environment. Using the measured β value in the vicinity of the current measured β value among the measured β values, the reciprocal of the change ratio of the measured β value to the recording power (the slope of the line segment K in FIG. 2B) A is used as the correction coefficient. calculate. Further, the microcomputer unit 13 calculates the walking OPC power-up rate R _UP by the equation (1) using this correction coefficient (SP8).

The microcomputer unit 13 calculates the corrected recording power based on the walking OPC power up rate R _UP calculated as described above, and then uses this as the new target recording power for APC control. 14 (SP10).

  Then, the microcomputer unit 13 determines whether or not all data to be recorded has been recorded on the optical disc 2 (SP11). If a negative result is obtained, the microcomputer unit 13 returns to step SP2, and thereafter repeats the same processing ( SP2-SP11).

  When the microcomputer unit 13 eventually records all the data to be recorded on the optical disc 2 and obtains a positive result in step SP11, the microcomputer unit 13 ends the recording power control process (SP12).

(3) Effects of this Embodiment As described above, in the optical disc apparatus 1 according to this embodiment, the correction coefficient is calculated based on the β value obtained by the walking OPC, and the recording power is corrected based on this correction coefficient. To do.

  Therefore, according to the optical disc apparatus 1, the target recording power optimum for the characteristics of the target optical disc and the current environment is set, and the recording power is corrected so as to be the target recording power. Power control can be performed. Thus, the recording quality at the time of data recording on the optical disc can be ensured.

  Further, in the optical disc apparatus 1, after obtaining the measured β value for a plurality of times, the correction coefficient is calculated using the measured β value obtained this time and the measured β value near the measured β value. A correction coefficient suitable for the current environment can be obtained, and accordingly, more accurate recording power control can be performed.

  Further, in the optical disc apparatus 1, when the current recording power is different from the past recording power and the measured β value obtained this time exceeds a predetermined error range from any measured β value obtained in the past, Since the recording power is corrected using a fixed correction coefficient set in advance, even when the measured β value suddenly changes due to a sudden environmental change, the measured β value affects the calculation of the correction coefficient. Therefore, more accurate recording power control can be performed.

(4) Other Embodiments In the above-described embodiment, the case where the present invention is applied to the optical disk apparatus 1 corresponding to the three types of optical disks 2 of BD, DVD, and CD has been described. The invention is not limited to this, and can be widely applied to various other optical disc apparatuses.

  In the above-described embodiment, the measured β value for the recording power is obtained using the measured β value acquired this time and the measured β value in the vicinity of the current measured β value among the measured β values acquired up to the previous time. Although the case where the reciprocal of the change ratio is calculated as the correction coefficient has been described, the present invention is not limited to this, and all the measurement β values acquired this time and the previous time are used, for example, each measurement β for the recording power The reciprocal of the slope of the approximate straight line of values may be calculated as a correction coefficient, and various other calculation methods can be widely applied as the correction coefficient calculation method.

Further, in the above-described embodiment, the walking power OPC power up rate R _UP of the recording power is calculated by the equation (1) using the calculated correction coefficient, and the recording power is corrected based on the walking OPC power up rate R _UP. However, the present invention is not limited to this, and various other correction methods can be widely applied as a recording power correction method using such a correction coefficient.

  Further, in the above-described embodiment, the reproducing unit that reproduces the data recorded on the optical disc 2 is constituted by the optical pickup 16, the analog / digital converting unit 17, and the digital signal processor 14, and the reproduced data is included in the reproduced data. A β value acquisition unit for acquiring a measured β value based on the digital signal processor 14, calculates a correction coefficient for the recording power based on the acquired measured β values for a plurality of times, and after correction to be targeted The target recording power calculation unit that calculates the recording power using the correction coefficient is configured by the microcomputer unit 13, and the recording power correction unit that corrects the recording power based on the calculated corrected recording power is digital The case where the signal processor 14 is used is described. Is not limited to this, these reproduction unit, beta value obtaining unit, a configuration of the recording power calculating unit and the recording power correction unit can widely apply various other configurations.

It is a block diagram which shows the structure of the optical disk apparatus by this Embodiment. It is a graph with which it uses for description of the recording power control system in the optical disk device by this Embodiment. It is a chart which shows a storage table. It is a graph with which it uses for description of the recording power control system in the optical disk device by this Embodiment. It is a flowchart which shows the process sequence of the recording power control process in a microcomputer part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical disk apparatus, 2 ... Optical disk, 3 ... Host computer, 13 ... Microcomputer part, 13A ... Memory, 14 ... Digital signal processor, 16 ... Optical pick-up, 20 ... Storage table.

Claims (10)

At the time of recording data on an optical disc, the recording quality of the data on the optical disc is periodically evaluated, and the optical disc apparatus controls the recording power based on the evaluation result.
A reproducing unit for reproducing the data recorded on the optical disc;
Based on the data reproduced by the reproduction unit, a β value acquisition unit that acquires a β value representing non-target amplitude;
Based on the obtained β values for a plurality of times, a correction coefficient composed of a conversion coefficient from β value to recording power is calculated, and a corrected recording power to be targeted is calculated using the correction coefficient. A power calculator,
An optical disc apparatus comprising: a recording power correction unit that corrects the recording power based on the corrected recording power calculated by the target recording power calculation unit. The target recording power calculation unit
The optical disc apparatus according to claim 1, wherein the reciprocal of the change ratio of the β value with respect to the recording power is calculated as the correction coefficient. The target recording power calculation unit
The correction coefficient is calculated based on the β value acquired this time and the β value in the vicinity of the β value acquired this time among the β values acquired in the past. Optical disk device. The target recording power calculation unit
2. The optical disc apparatus according to claim 1, wherein the corrected recording power is calculated using a predetermined correction coefficient set in advance until a predetermined number of β values are acquired. The target recording power calculation unit
When the current recording power is different from the past recording power and the β value obtained this time exceeds a predetermined error range from any of the β values obtained in the past, The optical disc apparatus according to claim 1, wherein the corrected recording power is calculated using a correction coefficient. In the recording power control method for periodically evaluating the recording quality of the data on the optical disc at the time of recording data on the optical disc and controlling the recording power based on the evaluation result,
A first step of reproducing the data recorded on the optical disc;
A second step of obtaining a β value representing non-target amplitude based on the reproduced data;
A correction coefficient that is a conversion coefficient from β value to recording power is calculated based on the obtained β values for a plurality of times, and a corrected recording power to be targeted is calculated using the correction coefficient. And the steps
And a fourth step of correcting the recording power based on the corrected recording power. In the third step,
The recording power control method according to claim 6, wherein the reciprocal of the change ratio of the β value with respect to the recording power is calculated as the correction coefficient. In the third step,
The correction coefficient is calculated based on the β value acquired this time and the β value in the vicinity of the β value acquired this time among the β values acquired in the past. Recording power control method. In the third step,
The recording power control method according to claim 6, wherein the corrected recording power is calculated using a predetermined correction coefficient set in advance until a predetermined number of β values are acquired. In the third step,
When the current recording power is different from the past recording power and the β value obtained this time exceeds a predetermined error range from any of the β values obtained in the past, The recording power control method according to claim 6, wherein the corrected recording power is calculated using a correction coefficient.

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