JP2007242171A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control laser power during reproduction of data on an optical disk depending on circumstances when the data is reproduced. <P>SOLUTION: This optical disk device has a laser power control part for controlling laser power 105 during reproduction to power different from laser power 104 during reproducing normal user data if a reproduced signal level obtained from reproduced light from an already recorded area to be reproduced is not stable when reproducing a recorded area 101 of an already recorded area of the optical disk. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus and relates to laser power during data reproduction.

  In order to read data from an optical disc and reproduce the data, a data recording area of the optical disc is irradiated with a laser adjusted to the power for data reproduction, and a reproduction signal is obtained from the reflected light from the disc to obtain desired data. In Patent Document 1, in a read-only area in which an address of an optical disk or the like is embedded as data, in order to improve a ratio between a signal to be detected and noise (hereinafter referred to as an S / N ratio), the read-only area is provided. As long as the laser power at the time of reproduction is increased, the device has been devised to acquire data from the read-only area.

Japanese Patent Application No. 11-285120

  Depending on the type of optical disc, there are optical discs with poor reflectivity, and discs with many defects such as warpage and unevenness. When the optical disk is played back, the S / N ratio of the playback signal is poor, and data and the target playback signal may not be acquired stably. In Patent Document 1, the laser power is increased during reproduction of the read-only area, and the S / N of the reproduction signal is increased. However, the power is not increased in the user data area, and data is stabilized in the user data area. I can't get it. Here, a method of collectively increasing the reproduction laser power in an area other than the read-only area is conceivable. However, by irradiating the data portion with more power than necessary, deterioration of the recorded user data area is accelerated. Or user data may be erased or overwritten in the user data area. For this reason, the method of simply increasing the reproduction laser power collectively improves the S / N ratio of the reproduction signal, but the above problem occurs and is not suitable for practical use.

  The above object can be achieved by the invention described in the claims.

  In other words, when reproducing data from an optical disc, the laser power during reproduction is controlled according to the situation.

  At the time of data reproduction, the data and signal level can be acquired stably, and data reproduction that is convenient for the user can be performed.

  The present invention controls the laser power during reproduction according to the situation when reproducing the recording part of an optical disc.

  In carrying out the present invention, it is not necessary to add a special function to the optical disc apparatus. FIG. 2 shows an optical disk device, and FIG. 1 shows some of the features of the present invention. A data reproduction method will be described with reference to FIGS.

  In the data reproduction method, in order to reproduce the data area, first, the drive control system 201 controls the spindle mechanism 204 to rotate the disk 202. Then, the drive control system 201 sets the power determined as the reproduction power in the laser control device 205. Thereby, the optical pickup 203 irradiates the disk 202 with the laser 208 with the power for reproduction. Thereafter, the position (hereinafter referred to as the address) of the optical disk on which the data is recorded is transmitted from the microcomputer control unit 209 to the drive control system 201, and the drive control system 201 moves the optical pickup 203 near the target address via the controller 207. Move. Thereafter, the reflected light is input to the optical pickup 203 as a reproduction signal, and the address detection unit 206 detects an address on the disk 202 currently scanned by the optical pickup 203. The detected address is transmitted to the drive control system 201. When the detected address becomes the target address, the data area is irradiated with laser light, and the reproduction light is input to the optical pickup 203. Data can be acquired from the reproduction signal obtained from the reproduction light. The above is the data reproduction method.

  FIG. 1 shows the relationship between the address of the optical disc and the laser power when a reproduction operation is executed in the data area. As shown in FIG. 1, when reproducing the reproduction target area 101, the laser power is changed at the address 102 at which the optical pickup 203 reaches the reproduction target area 101. As a result, the amplitude level of the reproduction light is changed in accordance with the reproduction target region 101, and the S / N ratio of the reproduction signal is improved.

  The laser power is changed at the address 102 that has reached the reproduction target area 101, but the address until the optical pickup 203 reaches the reproduction target area 101 is known by the drive control system 201. It is easy to run an example.

  This is an example in which a higher power than normal is required as a playback power in order to correctly acquire data during playback of the playback target area 101. In this case, laser light is emitted up to the start address 102 of the reproduction target area 101 while the normal user data reproduction power 104 is set in the laser controller 205. When the target address 102 matches the address detected by the current drive control system 201, the drive control system 201 instructs the laser control device 205 to use the laser power 105 determined in advance for reproduction of the reproduction target area 101. Should be set. Then, when the address 103 at the end of the reproduction target area 101 is reached, the drive control system 201 may reset the normal user data reproduction power 104 to the laser control apparatus 205 in the laser control apparatus 205. Thereby, the laser power can be varied only when the reproduction target area 101 is reproduced.

  Next, an example applied at the time of data reproduction at the time of recording laser power adjustment will be described. The recording laser power adjustment is a process of calculating the laser power at the time of recording suitable for the disc in order to stably record data on the target recording type disc. General recording laser power adjustment is an area where recording laser power is intentionally changed from low power to high power in a recording laser power adjustment area logically provided in the optical disc standard. , The relationship between the acquired index value and the laser power during recording is clarified, and the laser power corresponding to the target index value is calculated as the recording laser power from the relationship.

  As the index value obtained by reproducing the recording area, the modulation degree of the reproduction signal, the non-target property (asymmetry) of the reproduction signal, etc. are generally used.

  Here, the laser power during reproduction when adjusting the recording power is conventionally the same as the laser power for reproducing user data. In recording laser power adjustment, recording is performed with the laser power varied from low power to high power, so the area recorded at low power is in a better recording state than the area recorded at the optimum laser power on the disk Therefore, the S / N ratio of the reproduction signal obtained from the reproduction light is poor, and the index value cannot be acquired stably.

  Since the acquisition of the index value is unstable, when the recording laser power is calculated based on the erroneous acquisition value, the calculated laser power may be different from the power that should be originally calculated. When data is recorded with a power different from the power that should be calculated, the recording quality of the data is not guaranteed, and it is expected that there are many cases where the data cannot be reproduced.

  Therefore, in order to stably acquire the index value, considering that the laser power during reproduction when adjusting the recording laser power is set to a predetermined power (power higher than the power during user data reproduction), The amount of return light is increased, the S / N ratio of the reproduction signal is improved, and the recording laser power suitable for the disc can be stably calculated by adjusting the recording laser power.

  In the above example, since the laser power is increased when reproducing the area recorded for laser power adjustment, the data in the recording part may be erased, overwritten, or promoted deterioration. This is not a problem. This is because, first of all, the index value to be acquired by adjusting the recording laser power is the signal level itself of the reproduction light, and it is sufficient that the modulation degree and asymmetry can be recorded. Therefore, since the recording unit has no meaning as data, even if the data cannot be read, there is no problem. Second, an appropriate recording laser power for recording on a recording type disk depends on the output characteristics of the laser and the sensitivity characteristics of the recording film of the disk. Since the output characteristics of the laser and the sensitivity characteristics of the recording film of the disk vary depending on the temperature environment, the optimum recording laser power changes every moment. For this reason, when performing the recording laser power adjustment, the area recorded for adjustment should be reproduced as fresh as possible to calculate the recording laser power. Therefore, the area recorded for adjusting the recording laser power is not a problem because it can be said that there is almost no utility value after use for the adjustment or after a sufficient time has elapsed.

  By executing the above embodiment of the present invention, for example, a stable index value as shown in FIG. 3 can be obtained. FIG. 3 shows the relationship between the recording laser power when the recorded area for recording laser power adjustment is recorded in the recording laser power adjustment and the index value obtained when the area is reproduced when adjusting the recording laser power. This is a comparison between the case of reproduction by the method (Δ in FIG. 3) and the case of the embodiment to which the present invention is applied (● in FIG. 3). As shown in FIG. 3, the laser power at the time of reproducing user data according to the conventional method does not stabilize the acquisition of the index value 302 when reproducing an area recorded at a low power. Thus, the index value 301 can be stably obtained when the reproduction laser power at the time of laser power adjustment is higher than the power at the time of user data reproduction. 3 is approximated by a curve, and the recording laser power 304 to be a desired index value 303 is calculated from the curve, and the index value can be obtained stably up to the low power side. It can be said that the laser power can be calculated accurately and stably.

  In addition, since the recording laser power can be stably calculated, the adjustment failure occurs when the unexpected recording laser power is calculated. In a system that performs readjustment, the number of re-execution due to the adjustment failure decreases, and the performance of the optical disc apparatus decreases. There is also an effect that leads to improvement.

  In the embodiment of the present invention, it has been described that the power at the time of reproducing the recorded area for recording laser power adjustment is changed from the power at the time of reproducing user data. A variation of the method is described. In the example described above, the reproduction power determined in advance is set in the recording area for adjusting the recording laser power. However, it is not always necessary to set it. In the above-described example, the laser power at the time of reproducing the recorded area for recording laser power adjustment has been described as being higher than the power at the time of reproducing user data, but this is not necessarily required. What has been described above is one embodiment of the present invention.

  That is, the present invention can vary the power set according to the situation. For example, when adjusting the recording laser power for an unknown disk, the film surface characteristics of the disk cannot be grasped, so that the appropriate laser power is not known as the laser power for reproducing the recorded area for recording laser power adjustment. Hereinafter, as an example corresponding to the above example, an example of an application method of the present invention will be described with reference to FIG.

  FIG. 4 is a flowchart in which the features of the present invention are added to the recording laser power adjustment. When adjusting the recording laser power, after recording the data for power adjustment (402), the recorded area is reproduced with the power for reproducing the user data (403). The index value acquired from the reproduction light is confirmed (404). If the acquisition is impossible or the acquired index value is not an appropriate value, the power is gradually increased (405). The recorded area is reproduced, the index value acquisition result is confirmed, and when an appropriate index value is acquired, the recording laser power is calculated based on this index value (406). As a result, it is possible to avoid irradiating an unknown disk 202 with more power than necessary to the recording area for recording laser power adjustment and destroying the disk. Further, in the flowchart of FIG. 4, if the power value when the recorded area for recording laser power adjustment is finally reproduced is stored in the microcomputer control device 209 or the drive control device 201, the next recording laser When executing the power adjustment, the stored power may be set when the recorded area for recording laser power adjustment is reproduced. Thus, in the embodiment of the present invention, the power at the time of reproducing the recorded area for adjusting the recording laser power can be controlled according to the situation. Since the above-described example is an example, the power control method need not be limited to this.

  In the present invention, the recording laser power adjustment pre-recorded area does not have to be recorded in the power adjustment area logically provided in the optical disc standard. That is, the present invention is effective regardless of where the recorded area for recording laser power adjustment is on the disk. For example, there may be a recording area that does not make sense as data even in a recorded part existing in the user data area. For example, in the Blu-ray Disc standard, a laser power adjustment area (APC AREA) is prepared for each minimum recording unit (1 Cluster) of user data. If the recording laser power adjustment is to be performed by recording the data for adjusting the recording laser power in the APC AREA and reproducing the recorded part, the present invention is applied and the APC AREA reproduction is performed. What is necessary is just to change a laser power inside.

  As a useful application example of the present invention other than recording laser power adjustment, the present invention can be applied to a disk having a large number of recording layers. In recent years, as a recording type optical disc, there is a disc having a large number of recording layers in order to record more data on one disc. These disks have a lower reflectivity of laser light than single-layer disks. For this reason, the amount of return light when light is applied to the disk is reduced as compared with that of a single-layer disk, and the S / N ratio of the signal is deteriorated. In addition, when a defect such as warping or unevenness of the disc is added, the amount of return light when the light is applied to the disc is reduced, or the return light contains noise, so the playback signal that you want to detect is stable Can not get to.

  In this case as well, the present invention may be applied to adjust the reproduction laser power. In the case of a multi-layer disc, the reflectivity varies from layer to layer. Therefore, a reproducing power is prepared for each recording layer, and an appropriate laser power may be set according to the layer. When performing laser power adjustment in a multi-layer disc, it can be easily predicted that the S / N ratio of the reproduction signal will deteriorate. Therefore, by combining with the above-described example, the recording laser power can be calculated stably. become able to.

  In addition, there are cases where it is difficult to obtain data even in a user data area, not a special area, and the present invention is also applicable in such a case. For example, when playing a disc, if there is no fingerprint, such as when the data area to be played is dirty, it can be played when there is no fingerprint, but there is a lack of laser power during playback due to the fingerprint. It will be. In this case as well, the present invention is applied, and reproduction laser power may be increased and reproduced only in the fingerprint region. However, in this case, depending on the laser power set at the time of reproduction, it may be possible to cause deterioration or destruction of surrounding user data. Therefore, even if user data is not deteriorated as much as possible, even if it is deteriorated, the degree of deterioration does not appear remarkably. It is preferable to set such power. By considering the above, it is possible to avoid erasing or overwriting data.

Reproduction power control method characteristic in embodiments of the present invention Optical disk device configuration diagram of an embodiment of the present invention Comparison between the embodiment of the present invention and the conventional example Application examples of the present invention

Explanation of symbols

101 ... reproduction target area, 102 ... start address, 103 ... alternate address,
104: Normal user data reproduction power, 105: Laser power determined for reproduction,
201 ... drive control system, 202 ... disc, 203 ... optical pickup,
204 ... Spindle mechanism, 205 ... Laser control device, 206 ... Address detector,
207 ... Controller, 208 ... Laser, 209 ... Microcomputer controller,
301: Index value 302: Index value 303: Index value 304: Recording laser power

Claims (9)

  When reproducing the recorded area of the optical disc, if the reproduction signal level obtained from the reproduced light from the recorded area to be reproduced is not stable, the laser power during reproduction is different from the laser power during normal user data reproduction. An optical disc apparatus characterized by having power.   An optical disc apparatus characterized in that, when there are multiple recording films on an optical disc to be recorded, the laser power at the time of reproducing an already recorded area can be changed according to each layer. The optical disc device according to claim 2,
An optical disc apparatus characterized in that, when it is difficult to obtain a reproduction signal of an optical disc to be recorded, the laser power during reproduction of the recorded area can be changed according to each layer.   When adjusting the laser power for calculating the laser power for recording data on the optical disc, if the reproduction signal obtained from the reproduction light cannot be stably obtained during reproduction of the recorded area, the reproduction during reproduction for reproducing the recorded area is not possible. An optical disc apparatus characterized by varying laser power. The optical disk device according to claim 4,
An optical disk apparatus characterized by varying laser power when reproducing a recording area already recorded for laser power adjustment. The optical disk device according to claim 4,
An optical disc apparatus characterized by varying laser power when reproducing an area previously provided on an optical disc for recording laser power adjustment. The optical disk device according to claim 4,
An optical disc apparatus characterized in that an available laser power can be obtained for the next recording laser power adjustment based on a result at the time of reproducing the recorded area. The optical disk device according to any one of claims 1, 3, and 4,
An optical disc apparatus characterized in that a laser power when reproducing the recorded area is higher than a laser power when reproducing normal user data. An optical disc apparatus according to any one of claims 1 and 3,
An optical disc apparatus characterized in that a laser power that can be used at the time of reproducing the recorded area next time and reproducing of another recorded area can be obtained based on the result of reproducing the recorded area.

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