JP2008181575A - Disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately obtain optimal laser beam power to record data to be smoothly reproduced in an optical disk in a disk device having an OPC function. <P>SOLUTION: The disk device 1 includes a modulation calculation unit 6 for calculating modulation from a reproduced signal detected when an optical disk 2 is reproduced, an asymmetry calculation unit 7 for calculating asymmetry from the reproduced signal, and a control unit 8 for determining the power of a laser beam emitted from an optical pickup 4 based on the modulation and the asymmetry respectively calculated by the modulation calculation unit 6 and the asymmetry calculation unit 7. The control unit 8 eliminates asymmetry affected by noise based on the modulation. Thus, it is made possible for the control unit 8 to accurately determine optimal laser beam power. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a disk device having an OPC function for recording data by irradiating an optical disk with laser light.

  In a disk apparatus that records data on an optical disk such as a CD-R or DVD, the data is recorded by irradiating the optical disk with laser light to form pits. It is desirable that recorded data is reproduced smoothly without causing a reproduction error. In order for the recorded data to be reproduced smoothly, the pit shape needs to have a constant width and a sharp edge at the rear end of the pit. If the pit has a good shape, the optical pickup can read data from the optical disc smoothly.

  The disk device needs to irradiate the laser beam with an optimum laser beam power in order to form a pit having a good shape. Therefore, the disk device determines the optimum power of the laser light by so-called OPC (Optimum Power Control) before data recording, and irradiates the laser light with this determined power. However, depending on the determination method in which the OPC determines the optimum power, even when the disk device irradiates the laser beam with the power determined by the OPC, a pit having a good shape may not be formed on the optical disk. .

  Therefore, in Patent Document 1 and Patent Document 2, a so-called β value is calculated from the RF signal of the reproduced data, and a reference value used to determine the optimum laser light power is set based on this β value. Means are disclosed. Patent Document 3 discloses a technique for correcting an error of an RF signal used for determining an optimum laser light power.

However, in the techniques disclosed in Patent Documents 1 to 3, the processing becomes complicated because the optimum laser light power is determined after setting the reference value or correcting the error of the RF signal, and the optimum is quickly achieved. The laser light power could not be determined.
JP 2003-196833 A Japanese Patent Laid-Open No. 2003-6868 JP 2003-141724 A

  The present invention has been made to solve the above problems, and in a disk device for recording data by irradiating an optical disk with laser light, the type of optical disk and the position on the optical disk where pits are formed. Regardless, it is an object to acquire a laser beam power capable of recording smoothly reproduced data and record the data with the acquired laser beam power.

  In order to achieve the above object, the invention of claim 1 is a disc apparatus comprising: an optical pickup that irradiates a laser beam for recording / reproducing data on an optical disc; and a control unit that controls the power of the laser beam. When the optical pickup records data on the optical disc, the control unit changes the laser light power step by step in the optical pickup to determine the optimum laser light power suitable for the optical pickup to record data on the optical disc. The test data is recorded on the optical disc while the optical pickup reproduces the plurality of recorded test data, and the control unit calculates asymmetry and modulation of each reproduced test data, and modulates the test data from the plurality of test data. Test data that is greater than 0.25 and matches the predetermined asymmetry Identify data, to determine the power of the identified test data recorded laser light as the optimum laser light power, the optical pickup is obtained so as to record data on the optical disk at the optimum laser light power.

  According to a second aspect of the present invention, there is provided a disc apparatus comprising: an optical pickup that irradiates a laser beam for recording / reproducing data on the optical disc; and a control unit that controls the power of the laser beam. When recording data, the control unit determines the optimum laser light power suitable for the optical pickup to record data on the optical disk, and changes the test data while gradually changing the laser light power to the optical pickup. The optical pickup reproduces the plurality of recorded test data, and the control unit determines the optimum laser light power based on the asymmetry and modulation of each reproduced test data.

  According to a third aspect of the present invention, in the disk device of the second aspect, the control unit calculates asymmetry and modulation of each reproduced test data, and is larger than a predetermined modulation among the plurality of test data, In addition, test data matching a predetermined asymmetry is specified, and the power of the laser beam in which the specified test data is recorded is determined as the optimum laser beam power.

  According to the first aspect of the present invention, the control unit calculates the asymmetry and modulation of each reproduced test data, and the laser recording the test data whose modulation is greater than 0.25 and matches the predetermined asymmetry. The optical power is determined as the optimum laser beam power, and the optical pickup records data on the optical disc with the optimum laser beam power. Thereby, since the control unit can specify the test data necessary for specifying the optimum laser beam power from the plurality of test data, the optimum laser beam power can be accurately determined. Data can be recorded on the optical disc with the optimum laser beam power.

  According to the invention of claim 2, the control unit determines the optimum laser light power based on the asymmetry and modulation of each reproduced test data. Thereby, the control part can avoid determining the laser beam power which is not the optimal laser beam power as the optimal laser beam power.

  According to the invention of claim 3, the control unit specifies test data that is larger than the predetermined modulation and matches the predetermined asymmetry from among the plurality of test data, and the specified test data is recorded. The power of the laser beam thus determined is determined as the optimum laser beam power. As a result, the control unit can easily specify the test data necessary for specifying the optimum laser beam power, so that the optimum laser beam power can be accurately determined.

  Hereinafter, a disk device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a disk device according to the present embodiment. The disc apparatus 1 includes a spindle motor 3 that rotates an optical disc 2, an optical pickup 4 that irradiates the optical disc 2 with laser light, a reproduction signal detection unit 5 that detects a reproduction signal from reflected light reflected by the optical disc 2, and a reproduction signal. Based on the modulation and asymmetry calculated by the modulation calculation unit 6 for calculating the modulation (modulation degree) from the above, the asymmetry calculation unit 7 for calculating the asymmetry (asymmetry) from the reproduction signal, the modulation calculation unit 6 and the asymmetry calculation unit 7 And a control unit 8 that determines the laser beam power irradiated by the optical pickup 4. The control unit 8 controls the spindle motor 3. Here, the optical disk 2 is, for example, DVD ± R or DVD ± RW.

  The optical pickup 4 receives a command from the control unit 8, a semiconductor laser 4 a (light emitting element) that irradiates the optical disc 2 with laser light, a beam splitter 4 b that transmits the laser light emitted from the semiconductor laser 4 a, and a beam splitter An objective lens 4c for condensing the laser beam transmitted through 4b on the optical disc 2 and a photodetector 4d for receiving the reflected light from the optical disc 2 whose direction has been changed by the beam splitter 4b and outputting a signal to the reproduction signal detector 5. (Light receiving element).

  When the disk device 1 records data on the optical disk 2, the semiconductor laser 4a records data by irradiating the optical disk 2 with laser light to form pits. At this time, if the formed pits are not in a good shape, the disk device 1 cannot read the recorded data smoothly. Here, the favorable shape of the pit means that the pit width is constant and the edge at the rear end of the pit is sharply formed. Reproduction of data recorded on the optical disc 2 is performed when the reproduction signal detector 5 detects the reproduction signal based on the reflected light of the laser beam irradiated on the pits. When the pit is not in a good shape, the reflected light of the laser light applied to the pit is disturbed, so that data cannot be reproduced smoothly.

  Therefore, the semiconductor laser 4a irradiates the laser beam with an optimum power corresponding to the type of the optical disc 2 in order to form a pit having a good shape. However, the optimum laser light power for forming a good-shaped pit varies depending on the data recording position in the circumferential direction of the optical disc 2 and the type of the optical disc. Therefore, the control unit 8 determines the laser beam power by OPC. OPC is an optimum laser beam power for recording data by writing data while changing the laser beam power in a trial writing area of data prepared on the optical disc 2, and reproducing the written data. Is a way to determine.

の式から算出する。また、アシンメトリ算出部７は、アシンメトリを、

の式から算出する。 FIG. 2 shows the waveform of the reproduction signal detected by the reproduction signal detector 5. The amplitude of the waveform can vary from the smallest amplitude with the smallest amplitude to the largest amplitude with the largest amplitude. Here, it is assumed that 3 TBottm is from the reference point serving as the amplitude reference to the lowest point of the minimum amplitude, and 3 TPeak is from the reference point to the highest point of the minimum amplitude. Also, 14 TBottm is from the reference point to the lowest point of the maximum amplitude, and 14 TPeak is from the reference point to the highest point of the maximum amplitude. Here, T is a reference clock indicating the period of the waveform. The modulation calculation unit 6 and the asymmetry calculation unit 7 calculate modulation and asymmetry from the amplitude of the waveform of the reproduction signal. The modulation calculation unit 6 converts the modulation into

It is calculated from the formula of Further, the asymmetry calculation unit 7 calculates the asymmetry as

It is calculated from the formula of

  FIG. 3 shows changes in the power of laser light in OPC. The controller 8 records data while gradually increasing the laser light power in the test writing area on the optical disk 2 in order to determine the optimum laser light power for writing data on the optical disk 2. Here, the control unit 8 changes the laser beam power by 11 steps. In FIG. 3, the vertical axis indicates the laser light power, and the horizontal axis indicates the light emission step in which the laser light power increases stepwise. Here, the straight line is a linear function indicating a change in laser light power that increases step by step, and is a laser light power straight line. The controller 8 determines the optimum laser beam power from the reproduction signal of the data recorded with each laser beam power.

  FIG. 4 shows changes in asymmetry in OPC. The reproduction signal detector 5 detects the reproduction signal by reproducing the data recorded in accordance with each light emission step. The asymmetry calculation unit 7 calculates asymmetry at each light emission step from the reproduction signal. In FIG. 4, the vertical axis indicates asymmetry, and the horizontal axis indicates a light emission step in which the laser light power increases stepwise. The value of asymmetry increases from the light emission step 1 to the light emission step 2, and the value decreases in the light emission step 3. Thereafter, the asymmetry increases from the light emission step 3 to the light emission step 11. The control unit 8 detects an intersection point P between the graph showing the change in asymmetry and the target target asymmetry in order to identify the light emission step that outputs the optimum laser light power. Here, the target asymmetry is 0, for example.

  In FIG. 4, there are three intersections P between the graph showing the change in asymmetry and the target target asymmetry. Assume that the intersection point P in the light emission step 1 is the intersection point P1, the intersection point P in the light emission step 2 is the intersection point P2, and the intersection point P in the light emission step 6 is the intersection point P3. The cause of the existence of the plurality of intersections P1 to P3 is considered that the reproduction signal detected by the reproduction signal detector 5 is highly likely to be affected by noise inside the disk device 1. When the reproduction signal is affected by noise, the value of the asymmetry changes irregularly. Therefore, it is considered that the increase / decrease in asymmetry in the light emission step 1 to the light emission step 3 is highly likely to be affected by noise. Here, when the control unit 8 determines the laser light power in the light emission step where the intersection P1 or the intersection P2 exists as the optimum laser light power, the data is written with a laser light power that is not suitable for recording data. . Therefore, in addition to asymmetry, the control unit 8 specifies a light emission step that provides the optimum laser light power based on the modulation.

  FIG. 5 shows the change in modulation in OPC. The modulation calculation unit 6 calculates the modulation at each light emission step from the reproduction signal. In FIG. 5, the vertical axis indicates modulation, and the horizontal axis indicates a light emission step in which the laser light power increases stepwise. The modulation increases from the light emission step 1 to the light emission step 11. The control unit 8 detects an intersection point Q between a graph indicating a change in modulation and a predetermined modulation threshold value in order to identify a light emission step that outputs an optimum laser beam power. Here, the modulation threshold is, for example, 0.25. The control unit 8 determines that the modulation smaller than the modulation threshold is affected by noise. For this reason, the light emission step in which the modulation smaller than the modulation threshold exists is excluded from the light emission step referred to when determining the optimum laser light power. Here, since the intersection point Q1 exists in the light emission step 2, the control unit 8 does not refer to the light emission step 1 and the light emission step 2 when specifying the light emission step.

  FIG. 6 shows a change in the power of laser light in OPC. In FIG. 6, the vertical axis indicates asymmetry, and the horizontal axis indicates a light emission step in which the laser light power increases stepwise. The control unit 8 refers to the asymmetry from the light emission step 3 to the light emission step 11 based on the modulation and the modulation threshold in FIG. 5 and identifies the light emission step that provides the optimum laser light power. For this reason, the control unit 8 determines that the asymmetry in the light emission step 1 and the light emission step 2 indicated by the broken line is affected by noise, and determines the optimum laser light power when the light emission step 1 and the light emission step 2 are performed. The asymmetry in is not referred to. The control unit 8 detects an intersection point P between the graph showing the change in asymmetry from the light emission step 3 to the light emission step 11 and the target asymmetry. Next, the control unit 8 obtains an intersection between the intersection P and the light emission step as Step P.

  FIG. 7 shows a laser light power line in OPC. In FIG. 7, the vertical axis indicates the laser beam power, and the horizontal axis indicates the light emission step in which the laser beam power increases stepwise. The control unit 8 obtains the laser light power in step P from the laser light power line, and determines this laser light power as the optimum laser light power. The control unit 8 records data on the optical disc 2 with the optimum laser light power determined by the optical hip-up 4.

  Thus, in the present embodiment, the control unit 8 excludes the asymmetry affected by noise based on the modulation, and then determines the laser light power that becomes the target asymmetry as the optimum laser light power. As a result, the control unit 8 can accurately determine the optimum laser light power that can record data in the optical disk 2.

In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible, for example,
Instead of the configuration including the modulation calculation unit 6 and the asymmetry calculation unit 7, respectively, the configuration may include a calculation unit capable of calculating modulation and asymmetry. Further, the control unit 8 may be configured such that the modulation threshold value is not 0.25, but 0.3, for example. Further, the control unit 8 may have a configuration in which the target asymmetry is not 0, but, for example, 1.

1 is a configuration diagram showing an outline of a disk device according to an embodiment of the present invention. The data recording processing flowchart which concerns on this embodiment. The figure which shows the change of the power of the laser beam in OPC which concerns on this embodiment. The figure which shows the change of the asymmetry in OPC which concerns on this embodiment. The figure which shows the change of the modulation in OPC which concerns on this embodiment. The figure which shows the change of the asymmetry in OPC which concerns on this embodiment. The figure which shows the laser beam power straight line in OPC which concerns on this embodiment.

Explanation of symbols

1 Disc device 2 Optical disc 4 Optical pickup 8 Control unit

Claims (3)

An optical pickup that irradiates a laser beam to record and reproduce data on an optical disc;
In a disk device comprising a control unit for controlling the power of the laser beam,
When the optical pickup records data on the optical disc,
The control unit is configured to determine the optimum laser beam power suitable for the optical pickup to record data on the optical disc, and to change the laser beam power to the optical pickup in a stepwise manner. Recorded on an optical disc,
The optical pickup reproduces a plurality of recorded test data,
The control unit calculates asymmetry and modulation of each of the reproduced test data, and calculates the test data that is greater than 0.25 and matches a predetermined asymmetry from among the plurality of test data. Determining the power of the laser beam in which the specified test data is recorded as the optimum laser beam power;
The optical pickup records the data on the optical disc with the optimum laser light power. An optical pickup that irradiates a laser beam to record and reproduce data on an optical disc;
In a disk device comprising a control unit for controlling the power of the laser beam,
When the optical pickup records data on the optical disc,
The control unit is configured to determine the optimum laser beam power suitable for the optical pickup to record data on the optical disc, and to change the laser beam power to the optical pickup in a stepwise manner. Recorded on an optical disc,
The optical pickup reproduces a plurality of recorded test data,
The disk unit characterized in that the control unit determines the optimum laser light power based on asymmetry and modulation of each reproduced test data.   The control unit calculates asymmetry and modulation of each of the reproduced test data, and selects the test data that is larger than the predetermined modulation and matches the predetermined asymmetry from among the plurality of test data. 3. The disk apparatus according to claim 2, wherein the disk device is identified and the power of the laser beam in which the identified test data is recorded is determined as the optimum laser beam power.

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