JP2007242138A - Optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the recording quality by carrying out the running OPC (ROPC) without fail in an optical disk drive. <P>SOLUTION: The ROPC is performed by using the remaining areas in the APC operation areas out of the APC areas 100 of the recording unit blocks (RUB) in next-generation optical disks such as blue-ray disks. In ROPC, test data of the 50T longer than the predetermined length for the data to be written is test-written in order to detect the level B of the return light. The APC area 100 consists of 5 wobble periods. The APC is performed in the first 2 wobble periods, and the ROPC is performed in the other 3 wobble periods. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disk apparatus, and more particularly to adjustment of recording laser light power.

  Conventionally, when data is recorded on an optical disc, test data is recorded by changing the recording laser light power in a predetermined test area of the optical disc, the test data is reproduced, and the optimum recording power is determined based on the reproduction quality. Along with the OPC technology to be set, ROPC (running OPC) that detects the amount of reflected light from the optical disk during actual data recording and adjusts the recording laser light power in accordance with the reflected light amount has been put into practical use.

In ROPC, among the amount of reflected light during data recording, a level B portion in which a pit is formed by the recording laser beam and the reflected light amount is stabilized is sampled and detected. Increase or decrease the optical power. For example, if the recording laser light power is P and the value of level B is B, the recording laser light power P is adjusted so that B / P ⁿ is constant. For example, n is set to 2 or the like.

  Sampling of the level B portion is conveniently performed with pits having a data length as long as possible in consideration of the time required to stabilize level B, the filtering band, and the like. For example, in a DVD, the value of level B is obtained by sampling the amount of reflected light at a data length of 9T to 11T, 14T, or the like.

  In the following patent document, an optical disc apparatus that rotates a disc provided with a test writing area, a buffer area, a lead-in area, a program area, and a lead-out area from the inner circumference side toward the outer circumference side at a constant angular velocity. In addition, it is described that a test signal is recorded in the outer peripheral area outside the test writing area and the lead-out area, and the setting operation of the laser output value is performed by reproducing the recorded test signal.

JP 2002-157738 A

  In ROPC, as described above, level B is detected at the timing of recording a pit having a data length as long as possible. Recently, the absolute time of a recording pulse is shortened in response to a request for increasing the data recording speed. Even if attention is paid to long pits, it is extremely difficult to detect level B stably.

  Furthermore, when the type of the optical disk is changed, there may be a case where there is no pit having a long data length. For example, a Blu-ray disc, which is one of the next generation optical discs, has a maximum data length of 8T, and even a sync signal has a data length of 9T, making level B detection more difficult.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to reliably execute ROPC and perform a recording laser regardless of an increase in data recording speed or a short data length of a next-generation optical disk. An object of the present invention is to provide an optical disc apparatus capable of adjusting the power of light and ensuring recording quality.

  The present invention is an optical disc apparatus for recording data for each predetermined recording block, the recording block including a user data area, an irradiation means for irradiating a recording laser beam, and the user data area of the recording block A power adjustment unit that irradiates the recording laser light in a predetermined area other than the test area to test-write test data having a predetermined data length, and adjusts the recording laser light power in accordance with the amount of reflected light at the time of test writing; In some cases, the recording laser beam power is repeatedly adjusted for each predetermined recording block.

  In one embodiment of the present invention, the predetermined area other than the user data area is an APC area (auto power control area) for adjusting power, and the relationship between the current and the light emission amount in the APC area. The data of the predetermined data length is test-written using the remaining area of the area used for calculation and power adjustment (APC). The predetermined data length is preferably a data length longer than the prescribed data length of the data to be recorded.

  According to the present invention, since ROPC is executed in a predetermined area other than the user data area in the recording block, it is possible to ensure the recording quality while ensuring the execution of ROPC. In particular, it is possible to cope with an increase in recording speed by using the remaining area of the APC area and using test data having a data length longer than the prescribed data length of data to be recorded.

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

  FIG. 1 shows an overall configuration diagram of an optical disc apparatus according to the present embodiment. A data recordable optical disk 10 such as a DVD or a next generation optical disk (Blu-ray) is driven to rotate by a spindle motor (SPM) 12. The spindle motor SPM 12 is driven by a driver 14, and the driver 14 is servo-controlled by a servo processor 30 so as to have a desired rotation speed.

  The optical pickup 16 includes a laser diode (LD) for irradiating the optical disk 10 with laser light and a photodetector (PD) that receives reflected light from the optical disk 10 and converts it into an electrical signal, and is disposed opposite to the optical disk 10. . The optical pickup 16 is driven in the radial direction of the optical disk 10 by a thread motor 18, and the thread motor 18 is driven by a driver 20. The driver 20 is servo-controlled by the servo processor 30 similarly to the driver 14. The LD of the optical pickup 16 is driven by a driver 22, and the driver 22 controls the light emission amount of the LD according to a command from the system controller 32. Although the driver 22 is provided separately from the optical pickup 16 in the figure, the driver 22 may be mounted on the optical pickup 16 as described later.

  When data recorded on the optical disk 10 is reproduced, a laser beam of reproduction power is irradiated from the LD of the optical pickup 16, and the reflected light is converted into an electric signal by the PD and output. A reproduction signal from the optical pickup 16 is supplied to the RF circuit 26. The RF circuit 26 generates a focus error signal and a tracking error signal from the reproduction signal and supplies them to the servo processor 30. The servo processor 30 servo-controls the optical pickup 16 based on these error signals, and maintains the optical pickup 16 in an on-focus state and an on-track state. Further, the RF circuit 26 supplies an address signal included in the reproduction signal to the address decoding circuit 28. The address decoding circuit 28 demodulates the address data of the optical disk 10 from the address signal and supplies it to the servo processor 30 and the system controller 32.

  One example of the address signal is a wobble signal. A wobble signal is wobbled by a modulated signal of time information indicating the absolute address of the optical disc 10, and the wobble signal is extracted from the reproduction signal and decoded to decode the address data (ATIP ) Can be obtained. Further, the RF circuit 26 supplies the reproduction RF signal to the binarization circuit 34. The binarization circuit 34 binarizes the reproduction signal and supplies the obtained signal to the encoding / decoding circuit 36. The encode / decode circuit 36 demodulates the binary signal and corrects errors to obtain reproduction data, and outputs the reproduction data to a host device such as a personal computer via the interface I / F 40. When the reproduction data is output to the host device, the encoding / decoding circuit 36 temporarily stores the reproduction data in the buffer memory 38 and outputs it.

  When data is recorded on the optical disk 10, data to be recorded from the host device is supplied to the encode / decode circuit 36 via the interface I / F 40. The encode / decode circuit 36 stores data to be recorded in the buffer memory 38, encodes the data to be recorded, and supplies the data to the write strategy circuit 42 as modulated data. The write strategy circuit 42 converts the modulation data into a multi-pulse (pulse train) according to a predetermined recording strategy, and supplies it to the driver 22 as recording data. Since the recording strategy affects the recording quality, it is usually fixed to a certain optimum strategy. The laser light whose power is modulated by the recording data is irradiated from the LD of the optical pickup 16 and the data is recorded on the optical disk 10. After recording the data, the optical pickup 16 reproduces the recorded data by irradiating a laser beam with a reproduction power, and supplies it to the RF circuit 26. The RF circuit 26 supplies the reproduction signal to the binarization circuit 34, and the binarized data is supplied to the encode / decode circuit 36. The encode / decode circuit 36 decodes the modulated data and collates it with recorded data stored in the buffer memory 38. The result of the verification is supplied to the system controller 32. The system controller 32 determines whether to continue recording data or execute a replacement process according to the result of verification.

  The system controller 32 controls the operation of the entire system, and particularly performs OPC and ROPC. In OPC, test data is trial-written in a test area of the optical disc 10 while changing the recording power stepwise, and the test data that has been trial-written is reproduced and its β value, γ value, modulation factor, error rate, etc. are measured. . Then, the recording power at which the reproduction signal quality such as the error rate becomes a desired value is selected and set as the optimum recording power Po. The system controller 32 controls the driver 22 so that the selected recording power Po is obtained. The system controller 32 also executes ROPC. In ROPC, as described above, the level B value when pits are formed by the recording laser beam is sampled, and the driver 22 is controlled according to the obtained level B value to increase or decrease the recording power.

  Hereinafter, ROPC processing in the system controller 32 will be described by taking Blu-ray as an example of the optical disc 10.

  FIG. 8 shows the data structure of Blu-ray. Data is managed for each recording unit block (RUB), and one RUB is a run-in part (Runin part) of 2760 channel bits (cbs), a physical cluster (Physical Cluster) of 496 × 1932 channel bits, and 1104 channel bits. It consists of a runout part (Runout part). A physical cluster is a user data area. Of the run-in part, the physical cluster, and the run-out part, an APC area is provided in the top run-in part. This APC area exists for 5 wobbles (5 × 69 channel bits), and APC is executed using this area. Here, “APC” means that the light emission characteristic of the laser diode (LD) is temperature-dependent, and the light emission amount can change even with the same drive current. Therefore, the relationship between the current (i) and the light emission amount (L). Is calculated, and the drive current for obtaining a desired light emission amount is adjusted. Using this APC region, the amount of light emission is detected by variously changing the drive current, the relationship between the current and the amount of light emission is calculated, and the process of calculating the drive current that provides the desired amount of light emission is executed. For example, the LD is driven at 5 mW and 15 mW, and the light emission amount at this time is detected by a light receiving element (front monitor) arranged in the vicinity of the LD, and the i-L characteristic of the LD is learned or corrected. As described above, the APC area is reserved for 5 wobbles. However, in order to actually learn or correct the i-L characteristics, 5 wobbles are not required, and the remaining areas of the APC area remain unused. Will remain.

  In this embodiment, paying attention to this unused area, ROPC is executed using a remaining area that is not used in APC in the APC area. For example, of the 5 wobble periods in the APC area, 2 wobble periods are used for APC, and the remaining 3 wobble periods are used for ROPC. In Blu-ray, only data of 2T to 8T (up to 9T when a synchronization signal is included) appears as a data length. However, since arbitrary test data can be written on the APC area, the data length is longer than 9T when ROPC is performed. Level B is detected by trial writing test data such as 50T.

  FIG. 2 shows a main configuration for performing APC and ROPC in the APC area of the recording unit block RUB. The optical pickup 16 is disposed in the vicinity of the LD, the quadrant photodetector PD, the objective lens, the objective lens driving circuit (focusing direction and tracking direction driving circuit), the driver (LDD) 22 for driving the LD, and the LD. And a front monitor (FMT) 16b for detecting the amount of emitted light. The front monitor 16b converts the amount of light emitted from the LD into an electrical signal and outputs it to the system controller 32.

  The quadrant photodetector detects the amount of reflected light (returned light amount) reflected by the optical disk 10 out of the laser light from the LD and supplies it to the low-pass filter LPF 44.

  The low-pass filter 44 removes a high frequency component included in the reflected light signal as noise and supplies it to the sample hold circuit S / H 46. The high frequency component includes, for example, a modulation component resulting from a recording strategy at the time of data recording. In the present embodiment, since the sample and hold is performed in test data having a long data length such as 50T, it is not necessary to set the cut-off frequency fc of the low-pass filter 44 high. The sample hold circuit S / H 46 samples and holds the signal from the low pass filter 44, detects the level B of the reflected light amount, and supplies it to the system controller 32. The sample hold timing in the sample hold circuit S / H 46 is given from the encoder 36. The encoder 36 receives the timing control signal Tapc from the formatter or timing generator indicating the APC area of the recording unit block RUB, and determines the start timing of the APC area based on this signal. A timing signal for executing APC in the two wobble period is supplied to the system controller 32, and an end timing signal for the two wobble period, that is, an ROPC start timing signal is supplied to the system controller 32 and the sample hold circuit S / H 46. . The sample hold circuit S / H 46 samples and holds the amount of reflected light according to the ROPC start timing signal from the encoder 36 and detects level B. Level B is a value at a timing when the pit is formed and the amount of reflected light is stabilized as described above, and is defined as a timing after a predetermined time has elapsed from the start timing of ROPC.

The encoder 36 supplies a recording pulse to the driver 22 to execute APC and ROPC in the APC area in accordance with a timing signal from the formatter or timing generator, and sets a predetermined recording strategy to record user data in the physical cluster. The following recording pulse is supplied to the driver 22. FIG. 3 shows an example of a recording strategy when user data is recorded. The recording strategy is composed of a leading pulse Ttop, followed by a multipulse Tmp, and a last pulse Tlp. The pulse width and pulse level (Pw) of the first pulse Ttop, the number and pulse level (Pb) of multiple pulses, the pulse width and pulse level (Pw) of the last pulse Tlp, the pulse width (Ts) and pulse level after the last pulse Tlp The recording strategy varies depending on (Pc). The leading pulse Ttop, the multipulse Tmp, and the last pulse Tlp are superimposed on the bias level Ps, but the bias level Ps is set to the reproduction level or the erase level. When the data length to be recorded is 2T, the multi-pulse Tmp and the last pulse Tlp do not exist only with the top pulse Ttop, and when the data length to be recorded is 3T, the top pulse Ttop and the last pulse Tlp exist and the multi-pulse There is no pulse Tmp. When the data length to be recorded is nT (n is 4 or more), all of the first pulse Ttop, the multipulse Tmp, and the last pulse Tlp exist,
Ttop + (n−3) × Tmp + Tlp
Given in. The recording strategy may be fixed or may be optimized during OPC execution.

When actual data is to be recorded, the above strategy is followed, but when APC is executed, it is sufficient to drive with a single pulse, and when ROPC is executed, test data is written on a trial basis. Any strategy can be used. However, in the present embodiment, the encoder 36 ensures the effectiveness of ROPC by performing test writing of test data and executing ROPC with the aid of a recording strategy for recording actual data. Specifically, in order to record test data with a data length of 50T, according to the above formula,
Ttop + 47 × Tmp + Tlp
Test-write test data with the following recording strategy.

The system controller 32 controls the driver 22 to execute APC and ROPC in the APC area according to the timing signal from the encoder 36. In ROPC, the following processing is executed. That is, first, OPC is executed in the Blu-ray test area to set the optimum recording power Po, 50T test data is written by trial using the set optimum recording power Po, and the reflected light level B at this time (this is expressed as follows). Bo)) is detected and stored in the memory. The recording power Po and the level B value Bo obtained in this way are combinations under ideal recording conditions. Then, at the time of actual data recording, sampling the value of the level B, and adjust the ^{Bo / Po n = B / P} n = recording power P to be constant. The recording power P may be adjusted by other methods using the obtained Po, Bo, and B. For example, to calculate the current recording power P and B / P ⁿ and a level B obtained, and the Bo / Po ⁿ which was magnitude comparison, a fixed amount according to the magnitude relationship only (e.g. ± 0.2 mW) The current recording power P may be adjusted up or down.

  FIG. 4 shows the execution timing of APC and ROPC in the APC area. The APC area 100 exists at the head of the recording unit block RUB, and the APC area 100 is divided into two parts, an APC operation area and an ROPC operation area. In the APC operation area, as shown in the figure, the LD is driven with two powers P1 and P2, and the light emission amount at that time is detected by the front monitor 16b to obtain the i-L characteristic. Based on the obtained i-L characteristics, a drive current that provides a desired light emission amount is calculated, and the LD is driven with the calculated drive current. The i-L characteristic of LD varies under the influence of temperature. Therefore, it is necessary to always correct or calibrate the i-L characteristic by executing APC for each RUB. In the ROPC operation area, 50T test data is recorded as described above, and the level B is detected by sample-holding the amount of reflected light during trial writing of the test data. By using 50T test data, multi-pulse noise can be sufficiently removed through the low-pass filter 44 having a sufficiently low bandwidth. For example, when the channel bit rate is 66 MHz, 50T corresponds to 0.76 μs, and therefore the cut-off frequency fc of the low-pass filter 44 can be lowered to 1.32 MHz in the lowest case. The figure shows a reflected light amount waveform (return light waveform), a waveform after passing through the low-pass filter 44, and a sample hold timing waveform of the sample hold circuit S / H46. Although the modulation component of the recording strategy is superimposed on the reflected light amount waveform, it can be seen that this modulation component is removed by the low-pass filter 44.

  As described above, ROPC is executed in the APC area that appears in a predetermined cycle, and data is recorded while adjusting the recording power. As shown in the figure, when ROPC is executed, 50T test data may be test-written only once to detect level B. However, the APC area 100 has 5 wobble periods, and when 3 wobble periods are allocated to ROPC, Since 3 × 69 = 207 channel bits can be secured, 50T test data can be test-written not only once but four times. Therefore, even if the recording power is changed stepwise when OPC is executed in a predetermined test area, even if ROT is executed by trial writing 50T test data by changing the recording power to a plurality of steps. Good.

FIG. 5 shows a timing chart when 50T test data is test-written by changing the recording power to P4, P5, P6, and P7. FIG. 5A shows a recording pulse waveform in which a recording strategy for trial writing 50T test data repeatedly appears four times. FIG. 5B shows the reflected light amount (return light) waveform at that time, and the signal waveform after passing through the low-pass filter 44 in the figure is shown by a solid line. FIG. 5C shows the sample hold timing of the sample hold circuit S / H46. A total of four sets of recording power and level B values are obtained by a total of four trial writings of 50T test data and sample hold of the amount of reflected light. These are (P4, B4), (P5, B5), (P6, B6), and (P7, B7). Next, to perform ROPC using these combinations,
Reflectance R = B / P
Is calculated. That is, R4 = B4 / P4, R5 = B5 / P5, R6 = B6 / P6, and R7 = B7 / P7 are calculated. Further, a relational expression between the reflectance R and the recording power is calculated. FIG. 6 shows the relationship between the recording power P and the reflectance R. The system controller 32 calculates f (Px, Rx) from the relationship between the recording power P and the reflectance R. Then, by calculating the ideal reflectance Ro from the ideal (Po, Bo) obtained at the time of executing the OPC, and substituting this ideal reflectance Ro into the relational expression f (Px, Rx), An ideal recording power at the ROPC execution position can be obtained. The ROPC process is summarized as follows.

(1) Execute OPC in the Blu-ray test area and test-write 50T test data with the optimum recording power Po to detect level B, and a combination of ideal recording power Po and level B value Bo Find (Po, Bo).
(2) An ideal reflectance Ro = Bo / Po is obtained from (Po, Bo).
(3) After APC is executed in the APC area, 50T test data is repeatedly written a plurality of times while changing the recording power in a plurality of stages, the level B at that time is detected, and the recording power P and level B are detected. Find a combination of
(4) The reflectance R is obtained from the combination of the recording power and the level B.
(5) A relational expression f (Px, Bx) between the recording power and the reflectance is calculated.
(6) The recording power is calculated from the ideal reflectance Ro and the relational expression f, and the current recording power is increased or decreased.

  In this embodiment, since ROPC is repeatedly executed in the APC area, the recording power can always be adjusted to the optimum value. Further, since ROPC is executed using test data having a long data length of 50T, it is possible to cope with an increase in recording speed.

  In this embodiment, of the 5 wobble periods in the APC area, 2 wobble periods are used for APC operations and the remaining 3 wobble periods are used for ROPC operations. However, 3 wobble periods are used for APC operations and the remaining 2 wobble periods are used. It can be arbitrarily set, for example, for ROPC operation. Further, the ratio for APC operation and ROPC operation may be adaptively changed for each optical disc or even for the same optical disc for each radial position. For example, 3 wobble periods are assigned for the APC operation on the inner circumference side, 2 wobble periods are assigned for the ROPC operation, 2 wobble periods are assigned for the APC operation on the outer circumference side, and 3 wobble periods are assigned for the ROPC operation. Since there is a possibility that the optimum recording power Po set by OPC can be applied as it is on the inner circumference side, five wobble periods may be allocated for APC operation on the inner circumference side, and the ROPC operation may not be performed. In general, since the necessity for ROPC increases toward the outer periphery, it is preferable to increase the ratio for ROPC operation in order to increase the execution accuracy of ROPC.

  FIG. 7 shows an example of the ratio of the ROPC operation area to the APC area. Three cases of a, b, and c are illustrated. The ratio a is a case where the ROPC ratio is fixed at 60% (3 wobble periods out of 5 wobble periods) regardless of the radius. The ratio b is a case where the ratio of ROPC is 40% up to a certain radius position r2 and increases to 60% at a radius larger than that. The ratio c is 0% until the radius r1, and the ROPC ratio is 0%, that is, only the APC is executed without executing the ROPC, and the ROPC ratio is sequentially increased according to the radial position from the radius r1 to the radius r2. In the above, the ROPC ratio is 100%, that is, only ROPC is executed. The ratio c indicates that APC and ROPC are not always executed in all areas of the optical disc 10, but APC and ROPC are executed using the APC area in at least some areas.

In this embodiment, the recording power is increased / decreased by using B / P or B / P ² when ROPC is executed, but more generally B / P ⁿ (n is a real number of 1 or more) is used. May be adjusted up or down.

1 is an overall configuration diagram of an optical disc apparatus according to an embodiment. It is a principal part block diagram of an optical disk device. It is explanatory drawing of a recording strategy. It is an execution timing chart of APC and ROPC. It is another execution timing chart of ROPC. It is a graph which shows the relationship between recording power and a reflectance. It is a graph which shows the relationship between the disc radius of an optical disc, and a ROPC ratio. It is data structure explanatory drawing of a Blu-ray disc.

Explanation of symbols

  10 optical disc, 16 optical pickup, 16b front monitor, 22 driver (LDD), 32 system controller, 36 encoder, 44 low-pass filter, 46 sample hold circuit.

Claims (10)

An optical disc apparatus for recording data for each predetermined recording block,
The recording block includes a user data area,
An irradiation means for irradiating a recording laser beam;
Power adjustment for irradiating the recording laser light in a predetermined area other than the user data area of the recording block to test-write test data having a predetermined data length, and adjusting the recording laser light power according to the amount of reflected light at the time of test writing Means,
An optical disc apparatus, wherein the recording laser light power is repeatedly adjusted for each of the predetermined recording blocks during data recording. The apparatus of claim 1.
The optical disk apparatus according to claim 1, wherein the predetermined area other than the user data area is an APC area for adjusting power. The apparatus of claim 2.
The optical disc apparatus characterized in that the power adjustment means trial-writes the data of the predetermined data length using a remaining area of an area used for calculating a relationship between current and light emission amount in the APC area. The apparatus of claim 1.
The optical disc apparatus characterized in that the predetermined data length is a data length longer than a prescribed data length of data to be recorded. The apparatus of claim 1.
The optical disc apparatus according to claim 1, wherein the test data recording strategy is the same as the data recording strategy. The apparatus of claim 1.
The power adjusting means adjusts the recording laser light power in accordance with a value of level B which is a reflected light amount at a timing when a pit is formed and a reflected light amount is stabilized when the test data is written by trial. Optical disk device to perform. The apparatus of claim 6.
The power adjusting means calculates B / P ⁿ (n is a real number of 1 or more) from the recording laser light power P when the test data is written on a trial basis and the value B of the level B, and B / P ⁿ An optical disk apparatus characterized by adjusting the recording laser light power according to the above. The apparatus of claim 6.
The power adjusting unit is configured to test-write a plurality of the test data by changing a recording laser beam power and adjust the recording laser beam power according to the value of the level B in each recording laser beam power. Optical disk device to perform. The apparatus of claim 3.
The ratio of the remaining area in the APC area is variably adjusted for each optical disk. The apparatus of claim 3.
The ratio of the remaining area in the APC area is variably adjusted according to the radial position of the optical disk.

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