JP2009199666A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device in which accurate setting of recording laser power is made possible even if linear velocity at OPC and at recording of information are different. <P>SOLUTION: Decision of a target β value in accordance with linear speed at recording or recording laser power becoming the asymmetry value is made based on relation between the β value detected at OPC or an asymmetry value and recording laser power. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus capable of setting an optimum laser power according to a linear velocity.

  The optical disk drive is mainly used as a peripheral device such as a personal computer, and has been developed as a large-capacity data storage device due to the ease of carrying the medium and the low cost. In particular, it has data accessibility advantages that cannot be realized with tape-like recording media, such as the ability to record continuous data intermittently, or the ability to reproduce arbitrary partial data from continuous length data at high speed and randomly. Yes. Today, optical disk drive devices are becoming increasingly denser and faster, and the transfer speed is increasing day and night, and the application to high-definition image information digital recording / reproducing devices is opened as the main axis of multimedia equipment.

  In such an optical disk drive device that achieves high speed and high density, adjustment of laser power in data recording or reproduction, that is, optimization is very important. The optimum laser power is affected by the track width and pitch, the groove shape, the material sensitivity of the dye film and the uniformity in the radial direction of the disk medium. In general, such individual differences are inherent to the disc, and the optimum laser power differs for different disc media. Even with the same disk medium, changes over time occur due to warpage of the disk medium, contamination on the surface of the disk medium, an increase in the number of times of use, and a storage state. Therefore, since the effective value of laser power changes, the optimum value of laser power varies. Also, in the recording / reproducing process for these disk media, temperature is an important parameter, and the optimum recording laser power or reproducing laser power varies depending on the temperature of the disk medium.

  In the known recording laser power optimization process, first, test recording is attempted in a predetermined area of the disk medium by changing the recording laser power stepwise. Next, the trial-recorded data is reproduced to obtain a recording laser power at which the best reproduction signal can be obtained. Such a process is called OPC (Optimum Power Control), and is performed according to each disk medium, each ambient temperature change, and each radial position of the disk medium, and the recording laser power that always provides the optimum recording quality is obtained. Is set.

  Conventionally, recording is usually performed while rotating a disk medium at a constant linear velocity (CLV). In this case, since the relative velocity between the disk medium and the laser beam is always constant, once the recording conditions are determined, recording can be performed using the laser power over the entire surface. Therefore, in the case of CLV, the entire recording surface of the disk is recorded by setting the recording laser power determined in the test writing area in the innermost periphery of the disk medium.

  However, if the linear velocity is constant, it is necessary to increase the number of rotations as the inner circumference increases, and as the speed increases, there are problems such as an increase in the cost of the spindle motor and the occurrence of vibration and noise.

  For this reason, a recording method that does not increase the number of rotations on the inner circumference is employed. In this method, there is ZCLV (Zone CLV) in which regions are divided by radial positions, the linear velocity is constant in each region, and the linear velocity is increased in the outer peripheral region. There is also a method of making the rotation speed constant (CAV: Constant Angular Velocity).

  In these methods, since the linear velocity is different between the inner circumference and the outer circumference, there is a case where information is recorded at a linear velocity different from the linear velocity when OPC is performed. Different linear velocities change the optimum recording laser power.

To solve such a problem, a method of increasing or decreasing the level of the recording laser power according to the frequency of the recording clock that changes in accordance with the linear velocity has been proposed.
Japanese Patent Laid-Open No. 11-296858

  However, the relationship between the linear velocity and the optimum recording laser power is not always linear. Therefore, when the recording laser power is monotonously increased or decreased according to the linear velocity as in the above-mentioned patent document, an error occurs in the recording laser power depending on the linear velocity. As a result, it becomes difficult to perform recording with stable quality on the entire surface of the disk medium.

  In view of such a problem, an object of the present invention is to provide an optical disc apparatus capable of accurately setting a recording laser power even when linear velocities are different between OPC and information recording.

  An optical disc apparatus according to the present invention comprises means for rotating an optical disc at a plurality of linear velocities, means for performing trial writing while changing recording laser power with respect to the optical disc at a predetermined linear velocity, and performing the trial writing. Means for reproducing the recorded area, means for detecting the β value or asymmetry value from the detected reproduction signal, detecting the relationship between the recording laser power and the β value or asymmetry value, and a line different from the predetermined linear velocity. Means for storing a target β value or asymmetry value corresponding to speed; and means for detecting a recording laser power that becomes the target β value or asymmetry value based on the relationship between the detected recording laser power and the β value or asymmetry value; It is what has.

  According to the optical disk apparatus of the present invention, the setting of the recording laser power that becomes the target β value or asymmetry value according to the linear velocity at the time of recording is made based on the relationship between the β value or asymmetry value detected during OPC and the recording laser power. Is doing. Therefore, the recording laser power can be determined with high accuracy, and recording can be performed with stable quality over the entire surface of the disk medium.

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

  The recording laser power learning according to the present invention is applied to, for example, an optical disc apparatus 100 as shown in FIG.

<Components and Series of Operations of Optical Disc Device 100>
The optical disc apparatus 100 includes an optical disc (hereinafter referred to as “disc”) 101, an optical pickup (hereinafter referred to as “OPU”) 120, and a spindle motor (hereinafter referred to as “SPM”) 110, which are disc-shaped recording media. Further, a spindle motor driver (hereinafter referred to as “SPM driver”) 109, an LD power control circuit 111, an actuator driver 113, a feed mechanism 112, a servo recording / reproducing processor 114, a disk controller (CPU) 115, an external interface 116, and a memory 117 are provided. I have.

  The detailed configuration and basic operation of FIG. 1 will be described.

  The disk controller 115 includes a CPU (Central Processing Unit). The overall operation of the optical disc apparatus 100 is controlled by executing a user instruction command or a predetermined program from an operation system (not shown) via the external interface 116. The recording or reproducing operation on the disc is performed with a known shock proof (intermittent drive) control via the memory 117.

  The disk 101 is a write-once (write-once) type disk having an organic dye in a recording layer, for example. In the write-once type, the intense light beam irradiated at the time of recording is absorbed by the dye film and is thermally altered, whereby the reflectance of the medium changes. Although this type of disc can be recorded only once, the demand for it is rapidly expanding because the player is compatible with reproduction and relatively inexpensive.

  Next, servo / recording / reproducing processing by the disk controller 115 and the servo recording / reproducing processor 114 will be described. The processor 114 performs rotational drive control of the SPM 110 by the SPM driver 111. Here, the rotation control of the spindle motor is so-called CLV (Constant Linear Velocity). The disk 101 has meandering sidewalls called wobbles along the track grooves. The disk rotation speed is controlled so that the frequency of the detected wobble signal becomes a target value.

  The OPU 103 includes an objective lens 102, an actuator 103, an optical system 104, an LD / driver 105, a reproduction signal sensor 106, an LD power monitor sensor 107, and a temperature sensor 108. The OPU 103 is connected to the servo recording / reproducing processor 114 or a motor / actuator driver system by a flexible cable or the like.

  The LD / driver 105 is a semiconductor laser element (hereinafter referred to as “LD”) and a laser driver. The laser beam emitted from the LD is irradiated onto the disk 101 via the optical system 104 and the objective lens 102. The LD power monitor sensor 107 includes a semiconductor light receiving sensor and a photoelectric conversion amplifier. A part of the laser light emitted from the LD is detected by the LD power monitor sensor 107, and the output thereof constitutes an APC (Auto Power Control) loop by the servo recording / reproducing processor 114 and the LD power control circuit 111. In other words, the LD emission power is feedback controlled so that the LD power monitor sensor output and the target power set by the disk controller 115 coincide.

  The reproduction signal sensor 106 includes a semiconductor light receiving sensor and a photoelectric conversion amplifier. FIG. 2 shows the arrangement of the light spots on the disk, the reproduction signal sensor configuration, and the arithmetic processing unit in the servo recording / reproducing processor.

  In the figure, the position of the main beam Main is controlled at the center of the track. The positions of the sub-beams SUB1 and SUB2 are shifted in the radial direction by 1/2 track with respect to the Main (differential push-pull method; Differential Push Pull).

The sensor unit corresponds to each of the three beams, the reflected light of the main beam Main is divided into four divided sensors (A to D), and the reflected light of the sub beams SUB1 and SUB2 is divided into two divided sensors (E to F, G to H). Irradiated. The reproduction signal sensor output is transmitted from the OPU 103 to the arithmetic processing unit of the servo recording / reproducing processor 114 via a flexible cable or the like. The arithmetic processing unit performs predetermined gain control (Auto Gain Control), filter processing (Pre Filter), and digitization (Analog / Digital Converter) to perform arithmetic processing on each of the A to H channel signals. Here, the SUM signal, which is the sum of the reflected light of the main beam, is
SUM = A + B + C + D
Is calculated and output. The difference signal of the diagonal sum of the quadrant sensor is calculated and output as a focus error / FE signal of the main beam (astigmatism method).
FE = (A + C)-(B + D)
The push-pull signal of the main beam is obtained as (A + D) − (B + C), but includes an offset due to the objective lens shift in the disk radial direction. Therefore, after the push-pull component (EF) + (GH) of the sub beam is multiplied by a predetermined coefficient k, a difference calculation is performed to generate a track error / TE signal in which the offset component is canceled.
TE = (A + D) − (B + C) −k {(E−F) + (G−H)}
The predetermined coefficient k is a constant determined in accordance with the divided light amount ratio between the main beam and the sub beam.

  As described above, the focus position control (focus control) of the light beam spot is performed based on the focus error / FE signal. Further, based on the tracking error / TE signal, tracking control is performed to control the tracking of the light beam spot in the groove direction with respect to the information track. The tracking control is controlled by fine adjustment in the actuator 103 and rough adjustment by the feed mechanism 112. That is, when it is detected that the position of the objective lens is located at the end of the movable range of the actuator, the feed mechanism is activated to transport the entire OPU 103 in the disk radial direction. In this way, the light beam spot is controlled to follow a predetermined track of the disk by combining fine control by the actuator and OPU transfer by the feed mechanism. The feed mechanism 112 transports the OPU 103 in the radial direction of the disk (traverse control) and performs a seek operation to a predetermined address.

  Next, the digitized reproduction signal is subjected to data processing by generating a clock synchronized with the edge of the reproduction signal by a PLL (Phase Locked Loop) (not shown). Further, predetermined decoding processing such as data detection by PRML (Partial-Response Maximum-Likelihood), ECC (Error Correction Code) is performed.

  On the other hand, for recording on the disk, the servo recording / reproducing processor 114 generates a recording pattern by modulation processing conforming to the disk format. The LD / driver 105 performs waveform shaping / timing control of the laser emission pulse in accordance with the recording pattern, and takes a so-called write strategy operation.

  The disk controller 115 performs recording by a shock proof operation. Specifically, the disk access is operated intermittently by utilizing the difference between the rate of data input to and output from the apparatus (low speed) and the rate of recording to the disk (high speed). In other words, while the signal from the external interface is accumulated in the memory 117, the disk access is put in a dormant state. The hibernation state is to turn off the LD with high power consumption and stop the operation of the related electric circuit block. When a predetermined amount of data is stored in the memory 117, disk access is started, and recording from the memory 117 to the disk 101 is performed. When recording to the disc is completed, the disc access is again set to the hibernation state. By intermittently accessing the disk in this manner, the LD can be turned off at the time of a pause, so that average power consumption can be reduced. Further, even if vibration or impact is applied from the outside of the apparatus, the memory 117 serves as a buffer, and servo return processing (retry processing) can be performed, so that an effect of improving seismic reliability can be obtained.

  Further, a temperature sensor 108 is provided inside the OPU 120 and has a function of detecting the temperature near the LD by the disk controller 115.

<OPC Flow of Optical Disc Device 100>
FIG. 3 shows a flowchart of OPC in the present invention. The OPC according to the present invention will be specifically described with reference to the block diagram of FIG. 1 and the flowchart of FIG.

  In this embodiment, the linear velocity for performing OPC is set to double speed, and the linear velocity for recording is set to 1.94 speed. Here, as an example, the linear velocity during OPC is set to double speed, and the linear velocity during recording is set to 1.94 times, but each linear velocity may be any number of times, and the linear velocity during OPC is the linear velocity during recording. Even if it is lower, the effect of the present invention can be obtained.

  First, the disk controller 115 issues a linear velocity change request to the processor 114. The processor 114 uses the SPM driver 1109 to control the SPM 110 so that the linear velocity becomes a double speed that is a linear velocity for performing OPC (S100).

  Next, trial writing is performed in the trial writing area of the disc. The disk controller 115 issues a request to move the OPU 120 to the processor 114 and moves to the test writing area. When the movement is completed, recording is performed while changing the disc and user information in a plurality of stages around a recommended recording laser power obtained in advance for each linear velocity for recording user information. (S101).

  Next, the recorded area is reproduced. The disk controller 115 issues a request to move the OPU 120 to the processor 114 and moves to the test writing area. When the movement is completed, the area recorded in S101 is reproduced, and a reproduction signal is taken into the processor 114 (S102).

  Next, the reproduction signal is evaluated. A beta (β) value is calculated from the reproduction signal fetched by the processor 114.

  Beta is expressed as follows.

The reproduction signal is AC coupled, the amplitude level is saturated amplitude level A ₁ and the lower side is the upper side of the saturated and was A _2. Amplitude level A ₁ for recording marks as the recording laser power is high is longer is larger than the amplitude level of A _2. On the other hand, towards the amplitude level of A ₂ is greater than the amplitude level A ₁ to a recording laser power is small recording mark is shortened. The difference between the amplitude levels of A ₁ and A ₂ is normalized by the overall amplitude level (A ₁ + A ₂ ) is β, and is expressed by the following equation.
β = (A ₁ −A ₂ ) / (A ₁ + A ₂ )
The β value is calculated for each of the recording laser powers changed in a plurality of stages in S101, and the relationship is stored in the memory 117 (S103).

  Next, the recording laser power at the linear velocity for recording user information is determined.

  The recording characteristics (target β value or target asymmetry value at the time of OPC and recording) of the disk to be used are checked in advance by the disk manufacturer or drive device manufacturer and stored as information in the disk or drive device.

  FIG. 4 shows the dependency of jitter and β on the recording laser power when recording is performed at 1.94 times speed and 2 times speed of the disk used in this embodiment. Note that jitter is reproduced at 1 × speed. The horizontal axis represents the recording laser power, and the vertical axis represents the jitter and β value representing the quality of the reproduction signal. The solid line shows the recording laser power dependency at 2 × speed, and the dotted line shows the recording laser power dependency at 1.94 times. Further, data plotted with circles indicate β values, and data plotted with triangles indicates jitter.

The recording laser power with the smallest jitter at 2 × speed is 21.5 mW at P ₂ in the figure, and the β value at that time is 6% which is β ₂ . If both twice the linear velocity of recording the OPC and the user information may be obtained a recording laser power in the OPC using the beta ₂ as a target beta value.

However, when the linear velocity at which user information is recorded is different as in this embodiment (1.94 times faster), the recording laser power at β ₂ is higher than the recording laser power at which jitter is minimized, and the jitter deteriorates. To do. Recording laser highest jitter is minimized at 1.94-times velocity power is 20.9mW a _{P 1.94} in FIG. The β value at that time is 3.0%, which is β _1.94 .

  In the present invention, when the linear velocity at the time of OPC and the linear velocity at the time of recording user information are different, the target β value at each linear velocity is examined in advance and stored in a disk or a memory in the drive device. Then, it is read out at the time of OPC, and based on the relationship between the β value stored in (S103) and the recording laser power, the recording laser power that becomes the read target β value is obtained. It should be noted that the linear velocity for performing OPC is preferably set to a linear velocity close to the linear velocity at the time of recording user information in order to increase the accuracy of OPC.

  FIG. 5 shows the relationship between the recording laser power and the β value as a result of the trial writing obtained in S103.

From FIG. 5, β _1.94, that is, 20.3 mW, which is the recording laser power at which the β value is 3.0%, is the optimum recording laser power. The recording laser power thus obtained is used for recording user information (S104).

  In the present embodiment, the β value of the reproduction signal is used as an index for determining the recording laser power. However, the same effect can be obtained by using the asymmetry value of the reproduction signal.

  Further, the OPC is performed by using the recording laser power with the smallest jitter as the target power, but the power with the largest recording laser power margin of the jitter and the power with the largest other margin may be set as the target power.

  In addition, the preferred embodiment of the present invention has been described with respect to the configuration based on hardware, but the gist of the present invention is not limited to this, and can of course be realized by software program processing. .

It is a functional block diagram of an optical disk device It is a figure explaining an actuator control signal It is a flowchart which shows the operation | movement in connection with embodiment of this invention. The relationship between recording laser power, β, and jitter in organic dye discs. It is the relationship between the recording laser power and β when trial writing is performed with the apparatus in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Optical disk 102 Objective lens 103 Actuator 104 Optical system 105 LD / driver 106 Playback signal sensor 107 LD power monitor sensor 108 Temperature sensor 109 SPM driver 110 SPM
111 LD Power Control Circuit 112 Feed Mechanism 113 Actuator Driver 114 Servo Recording / Reproduction Processor 115 Disk Controller 116 External Interface 117 Memory 120 Pickup (OPU)

Claims (1)

  Means for rotating the optical disk at a plurality of linear velocities; means for performing test writing while changing the recording laser power to the optical disk at a predetermined linear velocity; and means for reproducing the area where the test writing has been performed. Means for detecting a β value or an asymmetry value from the detected reproduction signal and detecting a relationship between the recording laser power and the β value or the asymmetry value, and a target β value corresponding to a linear velocity different from the predetermined linear velocity Or means for storing an asymmetry value, and means for detecting the recording laser power that becomes the target β value or asymmetry value based on the relationship between the detected recording laser power and the β value or asymmetry value. Optical disk device.

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