JP2007287214A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device for highly precisely adjust the increase and decrease of a recording power during data recording. <P>SOLUTION: A system controller 32 executes an OPC in a test area of an optical disk 10 and sets optimum recording power, while interrupts data recording at a prescribed timing during data recording and adjusts the increase and decrease of the optimum recording power. The system controller 32 test-writes test data by changing power prior to interruption of data recording, and relation between signal quality of the test data and power is calculated. The power is adjusted so as to obtain a target signal quality by using the calculated relation. The test data is erased by overwriting after power adjustment. <P>COPYRIGHT: (C)2008,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 beam power is P and the value of level B is B, the recording laser beam 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 previous recording quality is evaluated, so it is not affected by the data length at the time of recording, but the previous 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 relates to an optical disc apparatus for recording data on a rewritable optical disc, a data recording means for recording data by irradiating a recording laser beam, and a power for adjusting recording power by interrupting data recording at the time of data recording And adjusting the recording laser light before changing the recording laser power to test-write test data following the data and reproduce the test data written. Adjusting the power of the recording laser light according to the relationship between the signal quality and the power obtained, and the data recording means erases the test data by overwriting and recording the data after the power adjustment. To do.

  In one embodiment of the present invention, the power adjusting means evaluates the quality of the data recorded immediately before the interruption, and the recording is performed according to the relationship between the signal quality and power obtained by reproducing the test data written by trial writing. Adjust the laser beam power.

  In the present invention, when data recording is interrupted, test data is recorded subsequent to the recorded data prior to the interruption of data recording, and the recording power is adjusted by reproducing the recorded data. Since the test data is erased by overwriting with the original data to be recorded after the interruption, the test data does not remain on the optical disk and does not reduce the capacity of the optical disk. 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 rewritable optical disk 10 such as a DVD or a next-generation optical disk (Blu-ray) is rotationally driven 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.

  FIG. 2 shows a main configuration for adjusting the recording power. 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 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 bottom hold circuit 46 detects the bottom level of the sum signal and outputs it to the sample hold circuit 52.

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

  In response to the OPC timing signal from the system controller 32, the encoder 36a of the encode / decode circuit 36 increases the recording power in order to calculate the relationship between the recording power and the evaluation parameter prior to the interruption of data when the data is interrupted. A recording pulse that changes in a shape is generated and supplied to the driver 22. The driver 22 tests and writes test data according to 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 decoder 36b searches the test data recorded in a staircase pattern from the RF ID address and the wobble address during the trace of the recorded data, and sends the test data area timing to the system controller 32 when passing through the test data recording area. A signal to the effect is supplied. The system controller 32 evaluates the demodulated data based on this timing signal, 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. In the event of a failure, the interruption of data recording is determined.
(4) Prior to the interruption of data recording, following the recorded data, test data is written on a trial basis by changing the recording power stepwise.
(5) Data recording is interrupted after trial writing of test data.
(6) After interrupting the data recording, the test data written by trial writing 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.
(8) After adjusting the current recording power, the recording of data that should be recorded is resumed with the new recording power after the adjustment. At this time, the test data is overwritten and erased by restarting the recording so as to overwrite the recording area of the test data.

  FIG. 3 shows a recording pulse (or a light emission pattern from the LD) used for trial writing of test data executed prior to recording interruption. 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). For example, five wobble periods are assigned to the test data recording 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 sum signal waveform detected by the bottom hold circuit 46. This is the waveform. 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. Alternatively, the modulation degree m of the reproduction signal is defined as m = (A−B) / A, where A is the peak level and B is the bottom level. Using these values, the system controller 32 calculates the modulation degree m for each recording power and stores it in the memory.

  FIG. 5 shows a plot of m values (referred to as m1 to m5) calculated for each recording power (referred to as P1 to P5) changed in five stages. The system controller 32 calculates a relational expression m = f (P) between them using such a pair (P, m). Then, by substituting mt, which is the target m value, into this relational expression, the target recording power Pt is calculated, and the current recording power is increased or decreased.

  On the other hand, the vicinity of the target modulation degree mt is set immediately before the modulation degree is saturated and is often quite broad as a characteristic, and the accuracy of the target power Pt may not be ensured. Therefore, as shown in FIG. 6, test data is recorded with a recording power before and after the modulation degree mz (for example, a value of about 40% of the target modulation degree mt) in which the characteristics of the power P and the modulation degree m are linear. It is preferable to obtain a relational expression m = f (P), obtain a power Pz having a modulation degree mz from this relational expression, and then obtain an optimum power Pt by multiplying the power Pz by a constant.

  Alternatively, since a sudden change in recording power may cause an error during reproduction, the power between the current power Po before adjustment and the new power Pt after adjustment calculated according to FIG. 5 or FIG. Recording power may be used. That is, the next recording power Pk is Pk = Po + n · (Pt−Po) Po. Here, n is 0 <n <1.

  As described above, in the present embodiment, when data recording is interrupted, the test data is recorded after changing the recording power following the recorded data before the data recording is actually interrupted, and then the data recording is interrupted. Since the test data is reproduced and the recording power is adjusted, the recording power can be adjusted with high accuracy without depending on the in-plane sensitivity variation of the optical disk. In addition, since the test data is overwritten after adjusting the recording power, the test data is erased, so that the recording capacity does not decrease.

  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 the present embodiment, five wobble periods are assigned to the test data trial writing area. However, any period can be used as the test data trial writing area, and the area size may 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.

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 m value. It is another graph figure which shows the relationship between power and m value. It is another principal part block diagram of an optical disk apparatus.

Explanation of symbols

  10 optical disk, 16 optical pickup, 22 driver (LDD), 32 system controller, 43 peak hold circuit, 46 bottom hold circuit.

Claims (8)

An optical disk device for recording data on a rewritable optical disk,
Data recording means for recording data by irradiating a recording laser beam;
Power adjustment means for interrupting data recording and adjusting recording power during data recording;
Have
Prior to interrupting data recording, the power adjusting means changes the power of the recording laser beam to test-write test data following the data, and reproduces the test data that has been test-written. Adjust the power of the recording laser light according to the relationship with the power,
The optical disc apparatus characterized in that the data recording means erases the test data by overwriting the data with data after the power adjustment. The apparatus of claim 1.
The power adjusting means evaluates the quality of the data recorded immediately before the interruption, and adjusts the recording laser light power according to the relationship between the signal quality and power obtained by reproducing the test data written by trial writing. An optical disk device. 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 quality of the data is the degree of modulation,
The power adjusting means is
The relationship between the modulation factor and power obtained by reproducing the test data is calculated within a range where the modulation factor and power are linear characteristics,
Calculate the power to obtain a predetermined degree of modulation from the calculated relationship,
An optical disc apparatus that calculates an optimum power by multiplying the calculated power by a constant. The apparatus according to claim 1,
An optical disc apparatus characterized in that the size of the area for test writing the test data is variably adjusted according to the 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.

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