JP2007242139A - Optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase or decrease the recording power with high precision while recording data in an optical disk drive. <P>SOLUTION: The system controller 32 sets up the optimum recording power by carrying out OPC in the test area of an optical disk 10 and interrupts recording at a predetermined timing while recording data to adjust the optimal recording power by increasing or decreasing it. In the guard area at the interrupted positions, test data is written by changing the power to calculate the relationship between the signal quality of the test data and the power. Then the power is adjusted by using the calculated relationship to the power level for obtaining the desired signal quality. <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 according to the amount of reflected light, or interrupts data recording during the recording operation However, a technique (so-called reflection method) for evaluating the quality of data recorded immediately before and adjusting the recording laser beam power according to the evaluation result 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.

  On the other hand, in the retrospective method, data recording is interrupted and the immediately preceding recording quality is evaluated, so there is no influence on the data length at the time of recording, but the immediately preceding recording quality is, for example, β value, γ value, error rate, etc. In order to adjust the current recording laser light power according to the evaluation result, how to increase / decrease the recording laser light power with respect to the evaluation parameters such as β value and γ value, etc. That is, it is necessary to accurately know the relationship between the recording laser beam power and the evaluation parameter (for example, the characteristic curve between the recording laser beam power and the β value). Such knowledge can be acquired in the test area where OPC is performed, but the test sensitivity (PCA area) where OPC is performed and the area where data is actually recorded generally have different recording sensitivities. Therefore, it is difficult to accurately adjust the recording laser beam power.

  The present invention has been made in view of the above-described problems of the prior art, and its purpose is to reliably adjust the power of the recording laser beam regardless of the increase in the data recording speed or the short data length of the next generation optical disk. An object of the present invention is to provide an optical disc apparatus that can ensure 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, and an irradiation means for irradiating a recording laser beam, and data recording is interrupted at the time of data recording. Power adjustment means for adjusting the recording power, and when the data recording is interrupted, the power adjustment means tests the test data by changing the power in a predetermined area other than the user data area of the recording block. Power adjusting means for adjusting the recording laser light power according to the relationship between the signal quality and power obtained by writing and reproducing the test data written by trial writing is provided.

  In one embodiment of the present invention, the power adjusting means evaluates the quality of the data recorded immediately before the interruption, records the relation between the signal quality and power obtained by reproducing the test-written test data, and records immediately before the interruption. The recording laser light power is adjusted according to the quality of the data. The predetermined area other than the user data area is preferably an APC area for adjusting power.

  In the present invention, when data recording is interrupted, test data is used by using an area reserved for indicating the interruption or an area reserved for confirming the position at the time of interruption when data recording is resumed. The relationship between the signal quality and power is calculated, and the recording power is adjusted using this relationship. Since the area secured when the data recording is interrupted is data other than the user data area, the capacity of the optical disk is not reduced. In addition, since the relationship between signal quality and power is calculated at the portion where data recording is interrupted, the recording power adjustment accuracy is higher than when calculating the relationship between the two in a test area or the like where OPC is performed. improves.

  According to the present invention, data recording can be interrupted during data recording, and the recording power can be adjusted with high accuracy.

  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 in particular performs OPC prior to recording and recording power adjustment by a reflection method during data recording. 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. Further, the system controller 32 controls the driver 22 so as to increase / decrease the optimum recording power Po by a reflection method during data recording.

  Hereinafter, recording power adjustment processing during data recording 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). One RUB is a run-in area (Runin area) of 2760 channel bits (cbs), a physical cluster (Physical Cluster) of 496 × 1932 channel bits, and 1104 channel bits. A runout area (Runout area) and a guard area (Guard3) added when data recording is interrupted or stopped. A physical cluster is a user data area. Among the run-in area, physical cluster, run-out area, and guard area, the guard area is provided with a predetermined repetitive bit pattern area and an APC area. The guard area is 8 wobble periods (8 × 69 channel bits), among which the repeated bit pattern area is assigned 3 wobble periods, and the remaining 5 wobble periods are assigned to the APC area. Here, in “APC” (auto power control), 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 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. Further, since the APC area is also provided in the run-in area at the head of the RUB, it is not always necessary to use the APC area in the guard area. In this case, the 5 wobble period remains as an unused area.

  In the present embodiment, attention is paid to the APC area following the repeated bit pattern area among the guard areas recorded at the time of data interruption as described above, and the recording power and the evaluation parameter to be referred to in the reflection method using this APC area. Get relationship. That is, after the data recording is interrupted, the quality of the data recorded immediately before is evaluated, and the relationship between the recording power and the evaluation parameter is calculated using the APC area. Then, the current recording power is adjusted to increase or decrease using the previous quality and the calculated relationship. Since the relationship between the recording power and the evaluation parameter is calculated not in the test area where OPC is executed but in the area where data recording is interrupted, the recording power can be adjusted accurately.

  FIG. 2 shows a main configuration for adjusting the recording power in the APC area included in the guard area of the recording unit block RUB. The optical pickup 16 includes an LD, a quadrant photodetector PD, an objective lens, an objective lens drive circuit (drive circuit in the focus direction and tracking direction), and a driver (LDD) 22 that drives the LD.

  The difference signal (difference signal between the inner peripheral signal and the outer peripheral signal) from the four-divided photodetector is a reproduction system circuit (binarization circuit) 34 including a PLL circuit as a reproduction signal and a wobble signal, and a decoder of the encoding / decoding circuit 36. 36b. Also, the sum signal from the quadrant photodetector (the sum signal of the inner signal and the outer signal) is supplied to the low-pass filter and equalizer 41, where high frequency noise is removed and a predetermined frequency component is boosted to equalize the level. After that, it is supplied to the peak hold circuit 43, the average value circuit 44, and the bottom hold circuit 46.

  The peak hold circuit 43 detects the peak level of the sum signal and outputs it to the sample hold circuit (S / H) 48. The average value circuit 44 detects the average value of the sum signal and outputs it to the sample hold circuit 50. The bottom hold circuit 46 detects the bottom level of the sum signal and outputs it to the sample hold circuit 52.

  Sample and hold circuits 48, 50 and 52 sample and hold the peak level, average value level, and bottom level, respectively, and supply them to the system controller 32. The sample timing in the sample hold circuits 48, 50, 52 is given from the clock signal obtained by the PLL circuit of the reproduction system circuit 34.

  The encoder 36a of the encode / decode circuit 36 indicates an APC area following the repeated bit pattern area of the guard area (Guard3) to be recorded after the data is interrupted in accordance with the OPC timing signal from the formatter or timing generator. The timing signal Topc is received, and a recording pulse that changes the recording power stepwise is generated and supplied to the driver 22 in order to calculate the relationship between the recording power and the evaluation parameter. The driver 22 tests and writes test data in the APC area of the guard area in accordance with the recording pulse. A reproduction signal of the test data written by trial writing is supplied to the reproduction system circuit 34 and the decoder 36b, demodulated, and supplied to the system controller 32. The system controller 32 evaluates the demodulated data and calculates the relationship between the recording power and the evaluation parameter. For example, the β value of test data written by trial with each recording power is evaluated, and the relationship between the recording power and the β value is calculated. Then, using the β value of the data recorded immediately before and the relationship between the recording power and the β value, the recording power that is the target β value that should be originally obtained is calculated, and the recording power is increased or decreased. Specifically, the system controller 32 adjusts the recording power according to the following procedure.

(1) Prior to data recording, OPC is executed in the test area (PCA) of the optical disc 10 to set the optimum recording power Po.
(2) Data recording is performed with the optimum recording power Po.
(3) When data is recorded for a predetermined recording length, when data is recorded for a predetermined time, or when a predetermined amount of temperature rise is detected, or a buffer underrun occurs. Data recording is interrupted in the event of a failure.
(4) A bit pattern is repeatedly recorded in the guard area, and test data is test-written by changing the recording power stepwise in the APC area of the guard area.
(5) After completion of the trial writing, an arbitrary data portion immediately before the recording interruption is reproduced to evaluate the quality (for example, β value).
(6) The test data written by trial is reproduced to evaluate the quality, and the relationship between the recording power and the evaluation parameter is calculated.
(7) The current recording power is adjusted according to the result of (6) above or according to the relationship between (5) and (6) above.

  FIG. 3 shows a recording pulse (or light emission pattern from the LD) used for test writing of test data in the APC area of the guard area (Guard 3) to be recorded after the recording is interrupted. In FIG. 3, the recording power is changed in five stages. That is, the power reduced by 30% (0.7 Po), the power reduced by 15% (0.85 Po), the current power Po, and the power increased by 15% (1.15 Po) with respect to the current recording power Po. The power increased by 30% (1.3 Po). Of the five wobble periods in the APC area, one power is assigned to one wobble period and test data is written on a trial basis. The recording power is 0.7 Po in the first wobble period, the recording power is 0.85 Po in the second wobble period, and the like. The test data may be random or have a predetermined data length. In the figure, a repetition pattern of the shortest data and the longest data is used.

  FIG. 4 shows a reproduction signal waveform when the test data of FIG. 4A shows the sum signal waveform of the test data, FIG. 4B shows the waveform obtained by peak detection of the sum signal waveform by the peak hold circuit 43, and FIG. 4C shows the average value of the sum signal waveform by the average value circuit 44. FIG. 4D shows a waveform obtained by bottom-detecting the sum signal waveform by the bottom hold circuit 46. The β value of the reproduction signal is defined as β = (A−B) / (A + B), where A is the peak level of the reproduction signal coupled by RC and B is the bottom level. Using these values, the system controller 32 calculates the β value for each recording power and stores it in the memory. During reproduction of the APC area by the optical pickup 16, the decoder 36b transmits to the system controller 32 that it is the timing (test data reproduction timing). The system controller 32 responds to this timing signal for each recording power. The β value is calculated.

  FIG. 5 shows a plot of β values (referred to as β1 to β5) calculated for each recording power (referred to as P1 to P5) changed in five stages. The system controller 32 calculates a relational expression β = f (P) between the two using such a pair of (P, β). The target recording power Pm is calculated by substituting βm, which is the target β value, into the relational expression, and the current recording power is increased or decreased.

  On the other hand, since detection of β1 to β5 shown in FIG. 5 is performed in a short time, there is a risk of offset depending on the time constant of the detection circuit such as the peak hold circuit 43. Therefore, as shown in FIG. 6, the system controller 32 sets β = f (P) + α (α is a constant) on the assumption that an offset occurs in the relational expression β = f (P) of both, and records in this expression. Α is calculated by substituting a set of (P, β) obtained by reproducing the data recorded immediately before the interruption. The target recording power Pm is calculated by substituting βm, which is the target β value, in this relational expression, and the current recording power is increased or decreased. Of course, the β value as an evaluation parameter is just an example. Generally, when the evaluation parameter is Q, the relationship between both may be defined as Q = f (P) + α. The evaluation parameter Qo and the power Po may be determined.

  The system controller 32 may adjust the recording power by other methods. For example, since a sudden change in recording power may cause an error during reproduction, a certain coefficient k is used between the recording power Po immediately before interruption of data recording and the recording power Pm calculated by the above method. Recording power may be set. Specifically, the recording power is set by P = Po + k (Pm−Po) Po.

  Thus, in this embodiment, when data recording is interrupted, the relationship between the recording power and the evaluation parameter (β value, etc.) is calculated at the interrupted portion, and the recording power is adjusted accordingly. Accuracy is improved. Further, since the area used for calculating the relationship between the recording power and the evaluation parameter uses the guard area that is secured in advance when the data recording is interrupted, the recording capacity of the optical disc 10 is not reduced.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, Other forms are also possible.

  For example, in this embodiment, as shown in FIGS. 2 and 4, the sum signal is detected by an analog detection circuit such as the peak hold circuit 43 and supplied to the system controller 32. However, as shown in FIG. The A / D converter 54 may convert the digital signal and supply the digital signal to the system controller 32, and the system controller 32 may detect the peak value or the bottom value to calculate the β value.

  In this embodiment, test data is written by trial using all the 5 wobble periods of the APC area in the guard area. However, any period of the 5 wobble periods of the APC area is written by test writing. The area size can be fixed or variable. When making it variable, it is preferable to sequentially increase the area size according to the necessity of adjusting the recording power. For example, according to the radial position of the optical disc 10, the power is changed only in three steps using only three wobble periods in the inner peripheral portion of the optical disc 10 and the power is changed in five steps using all five wobble periods in the outer peripheral portion. Adjust the area size. The test data test writing area size may be variably adjusted according to the type of the optical disc 10. When only 3 wobble periods are used for test data writing, the remaining 2 wobble periods can be used for the original purpose APC.

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 the recording pulse which test-writes test data. It is a timing chart of a reproduction signal waveform (sum signal waveform) and a detection waveform. It is a graph which shows the relationship between power and (beta) value. It is another graph figure which shows the relationship between power and (beta) value. It is another principal part block diagram of an optical disk apparatus. It is data structure explanatory drawing of a Blu-ray disc.

Explanation of symbols

  10 optical disk, 16 optical pickup, 22 driver (LDD), 32 system controller, 43 peak hold circuit, 44 average value circuit, 46 bottom 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 means for interrupting data recording and adjusting recording power during data recording;
Have
When the data recording is interrupted, the power adjusting means is obtained by changing the power in a predetermined area other than the user data area of the recording block, writing test data, and reproducing the test data written by trial writing. An optical disc apparatus characterized in that the recording laser beam power is adjusted according to a relationship between signal quality and power. The apparatus of claim 1.
The power adjustment means evaluates the quality of the data recorded immediately before the interruption, and according to the relationship between the signal quality and power obtained by reproducing the test data written by trial and the quality of the data recorded immediately before the interruption. An optical disc apparatus for adjusting a recording laser beam power. The apparatus according to claim 1,
The optical disk apparatus according to claim 1, wherein the predetermined area other than the user data area is a guard area following the run-out area. The apparatus of claim 3.
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 provided in the guard area. The apparatus according to claim 1,
The optical disc apparatus characterized in that the power adjusting means interrupts data recording when data is recorded for a predetermined recording length or recording time. The apparatus according to claim 1,
The optical disc apparatus characterized in that the power adjustment means interrupts data recording when a predetermined amount of temperature change is detected. The apparatus according to claim 1,
The optical disc apparatus characterized in that the power adjusting means interrupts data recording at the time when a buffer underrun is detected. The apparatus of claim 2.
The power adjustment means calculates the relationship between the signal quality Q and the power P obtained by reproducing the test data written by trial writing as Q = f (P) + α with α as a predetermined offset, and interrupts data recording. The optical disk apparatus is characterized in that the offset α is calculated using the power Po immediately before and the signal quality Qo of the data. The apparatus according to claim 1,
An optical disc apparatus characterized in that a size of a test writing area of the test data in the predetermined area is variably adjusted according to a type of the optical disc. The apparatus according to claim 1,
The size of an area in which the test data in the predetermined area is trial-written is variably adjusted according to the radial position of the optical disk.

Images