JP2006114095A - Optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a sure execution of a border closing in an optical disk drive for recording data on a write once disk such as a DVD-R. <P>SOLUTION: A land prepit (LPP) signal contained in a reproduction signal of the optical disk 10 is extracted by an address decoding circuit 28. When the border closing for recording the predetermined data on a border out area is executed after the data are recorded, a system controller 32 instructs the address decoding circuit 28 so as to temporarily increase the threshold for detecting the land prepit (LPP) signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc apparatus, and more particularly to an optical disc apparatus for recording data on a write-once optical disc such as a DVD-R.

  An optical disc such as a DVD-R has wobbles and land pre-pits (LPP) formed in advance, detects wobble signals and LPP signals included in the reproduction signal, and records data in synchronization with them (pre-pit synchronization). Or LPP activation). If data has already been recorded, a timing signal can be extracted from the recorded data and data can be recorded based on the timing signal (data synchronization or ID activation).

  On the other hand, when recording data on a DVD-R, when recording data in the data area of the DVD-R in order to enable playback on a DVD player (playback-only player), the reserved recording zone is used. If an unrecorded area remains, “0” data is recorded and recorded, and predetermined data is recorded in the border-in area and the border-out area so as to sandwich the recorded zone, and border close is executed. .

  Here, the border-in area and the border-out area are areas that function as buffer areas for the optical pickup overrun when accessing the data area. Specifically, after the empty area is formed by 2 ECC blocks, the border area and the border-out area are 8 ECC blocks. Just close the border by recording data.

JP 2002-352522 A JP 2004-103046 A

  When executing the border close, since data of 8 ECC blocks is recorded following the empty area of 2 ECC blocks, the optical disc apparatus needs to detect the end of 2 ECC blocks. Since there is no data for two ECC blocks, data synchronization is impossible, so it is necessary to detect LPP and perform pre-pit synchronization.

  Usually, as shown in FIG. 4, since the LPP signal 100 appears as a pulse signal superimposed on the peak position of the wobble signal, the reproduction signal level is compared with a predetermined threshold level, and a pulse signal exceeding the threshold is detected. It is detected as an LPP signal 100 (see Patent Document 2 above). However, when an LPP signal is detected to execute border closing, there is a problem that the LPP signal cannot be detected due to the influence of adjacent tracks.

  FIG. 5 schematically shows the state of a track of a DVD-R disc. Of the tracks indicated by spirals in the figure, the solid line portion 200 is a track on which data has already been recorded, and the broken line portion 300 is an unrecorded track. When accessing the area A in the figure, both the inner and outer tracks are recorded tracks. When detecting the LPP signal, the modulation component is removed by calculating the difference between the inner peripheral detector signal and the outer peripheral detector of the quadrant photodetector provided in the optical pickup, but the adjacent inner peripheral track and the adjacent outer peripheral track are removed. When both are recorded tracks, the modulation component is canceled by the difference calculation, and the LPP signal can be easily detected.

  On the other hand, when accessing the area B or C in the figure, the inner track is a recorded track, but the outer track is an unrecorded track, so the difference between the inner detector and the outer detector. Even if the motion is calculated, the modulation component cannot be canceled out, and the modulation component remains. Therefore, even if binarization is performed using a threshold value, a lot of noise components are mixed, and it is difficult to detect the LPP signal. Therefore, the number of retries often increases. When executing the border close, it is necessary to detect the end of an unrecorded 2ECC block, access that position, and add data, so this corresponds to accessing the C area in the figure. The above problem becomes apparent.

  An object of the present invention is to provide an apparatus capable of reliably detecting a land pre-pit (LPP) signal even when executing border close.

  The present invention relates to an optical disc apparatus for recording data on an additionally recordable optical disc, and detecting means for detecting a land pre-pit formed on the optical disc by comparing a reproduction signal from the optical disc with a threshold value. And control means for increasing the threshold value when the border is closed by recording predetermined data in the border-out area of the optical disc.

  The present invention also relates to an optical disc apparatus for recording data on an additionally recordable optical disc, the photodetector having an inner circumference detector and an outer circumference detector for receiving reflected light from the optical disc, and the inner circumference detector. The difference calculator for calculating the difference between the signal from the outer detector and the signal from the outer peripheral detector, and the difference signal from the difference calculator and the threshold value are compared to output the land pre-pit signal included in the difference signal. And a controller for temporarily increasing the threshold value at the timing of starting border close in the border-out area of the optical disc.

  In the present invention, the influence of noise is suppressed by increasing in advance a threshold for detecting a land pre-pit signal when border closing is performed. This eliminates the need to re-detect the land pre-pit signal by adjusting the threshold value afterwards, thereby preventing a retry.

  According to the present invention, since the land pre-pit signal can be reliably detected even when the border is closed, the border close can be executed quickly.

  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 recordable optical disk 10 such as a DVD-R 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 is controlled by an auto power control circuit (APC) 24 so that the drive current becomes a desired value. The APC 24 controls the drive current of the driver 22 so that the optimum recording power selected by OPC (Optimum Power Control) executed in the test area (PCA) of the optical disc 10 is obtained. The OPC is a process of recording test data on the PCA of the optical disc 10 by changing the recording power in a plurality of stages, reproducing the test data, evaluating the signal quality, and selecting a recording power that can obtain a desired signal quality. It is. For the signal quality, β value, γ value, modulation factor, jitter, etc. are used.

  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 the reproduction signal to the address decoding circuit 28.

  The address decoding circuit 28 includes an LPP extraction unit and a decoding unit, binarizes the reproduction signal to extract the LPP signal, then decodes the extracted LPP to demodulate the address data, and the servo processor 30 and the system controller 32. To supply.

  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 8-16 modulation signal to the encoding / decoding circuit 36. In the encode / decode circuit 36, the binarized signal is demodulated and error-corrected by 8-16 to obtain reproduction data, and the reproduction data is output 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 recording data 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 8-16 modulation 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. The recording strategy is composed of, for example, the pulse width of the first pulse, the pulse width of the subsequent pulse, and the pulse duty in the multi-pulse. Since the recording strategy affects the recording quality, it is usually fixed to a certain optimum strategy. A recording strategy may be set at the time of OPC. 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 8-16 modulated data is supplied to the encode / decode circuit 36. The encode / decode circuit 36 decodes the 8-16 modulation data and collates it with the recording data stored in the buffer memory 38. The result of the verification is supplied to the system controller 32.

  The recording format for recording data is the same as the conventional one. That is, in the data area of the optical disc 10, an area for storing data to be recorded is reserved, and there is an unrecorded area among the reserved areas to enable playback on the DVD player after the recording is completed. In this case, “0” data is recorded in the area and recorded, and predetermined data is further recorded in the border-in area and the border-out area to close the border. In the border-out area, data for 8 ECC blocks is recorded following the empty space for 2 ECC blocks. When recording data for 8 ECC blocks, pre-pit synchronization using an LPP signal is used. That is, the optical pickup 16 seeks to the corresponding track position, the seek destination track is traced to detect the LPP signal, and the border closing data is recorded in synchronization with the LPP position. When data is recorded in all data areas of the optical disc 10, border close is executed and data is also recorded in the lead-out area for finalization. Data addition is impossible by finalization.

  Hereinafter, an operation of detecting the LPP signal when executing border close will be described.

  FIG. 2 schematically shows a four-divided photodetector 17 in the optical pickup 16. The quadrant photodetector 17 is composed of A, B, C, and D photodetectors, A and B, C and D are arranged in the radial direction (track width direction) of the optical disc 10, and A and D, and B and C are the optical disc 10. Are arranged in the circumferential direction (track extending direction). A and C, B and D are arranged diagonally.

  FIG. 3 shows a circuit configuration of the LPP extraction unit included in the address decoding circuit 28. The LPP extraction unit is supplied from the system controller 32 to the subtractor 56 that calculates the difference between the detector signals, the operational amplifier 58 that binarizes the LPP signal using a threshold value, and the inverting input terminal (−) of the operational amplifier 58. It includes a D / A 64 that converts a threshold value into an analog signal and supplies it.

  The signals of the A photo detector and the D photo detector are added by an adder 50 and supplied to an auto gain control circuit (AGC) 52. The signals of the B photo detector and the C photo detector are added by an adder 66 and supplied to the AGC 54. The two signals whose gains are adjusted by the AGC 52 and the AGC 54 so as to have the same amplitude are subjected to a difference calculation by the subtractor 56 and supplied to the non-inverting input terminal (+) of the operational amplifier 58. The operational amplifier 58 compares the reproduction signal including the differential signal, that is, the LPP signal, with the threshold value supplied to the inverting input terminal (−), extracts the LPP signal component, and outputs the LPP signal component to the decoding unit of the address decoding circuit 28. Although not shown, since the LPP signal superimposition timing is known, a window setting circuit that sets a processing window only in the time domain where the LPP signal will be present, and a counter circuit that counts the number of LPP signals These are known circuit elements of the LPP extraction unit.

  The system controller 32 detects an LPP signal using a predetermined threshold value during normal data recording, that is, when data is recorded on an unrecorded disc (virgin disc). If it is determined that it is time to start the process, the threshold value is uniformly increased by a predetermined amount or a predetermined ratio. That is, if the threshold value of the default value is Lth, the threshold value is temporarily changed to Lth ′ (Lth ′> Lth) when executing the border close. The changed threshold value is supplied from the D / A 64 to the operational amplifier 58, and the operational amplifier 58 detects the LPP signal with the changed threshold value Lth '.

  At the border close timing, since only the adjacent inner track is a recorded track, the modulation component of the adjacent track is superimposed on the difference signal from the subtractor 56 as a noise. By increasing to Lth ′, it is possible to extract only the LPP signal while eliminating the influence of these noises. After detecting the LPP signal and completing the border close in pre-pit synchronization, the system controller 32 returns the threshold value to the default value again to detect the LPP signal.

  If border closing is executed while the threshold value is maintained at the default value, the LPP signal cannot be detected and, as a result, retry is required. In this embodiment, the threshold value is set from the default value in advance at the timing of starting border closing. Since the threshold value is increased (the threshold value is not adjusted afterwards when the LPP signal cannot be detected, but the threshold value is adjusted in advance), the possibility of retry can be significantly reduced.

1 is an overall configuration diagram of an optical disc device according to an embodiment. It is arrangement | positioning explanatory drawing of a photodetector. It is a circuit diagram of the LPP extraction part in the address decoding circuit in FIG. It is a figure which shows the relationship between a wobble signal, an LPP signal, and a threshold level. It is a figure which shows the access position at the time of border close.

Explanation of symbols

  10 optical disk, 16 optical pickup, 28 address decoding circuit, 32 system controller.

Claims (2)

An optical disk device for recording data on an additionally recordable optical disk,
Detecting means for detecting a land pre-pit formed on the optical disc by comparing a reproduction signal from the optical disc with a threshold value;
Control means for increasing the threshold when closing the border by recording predetermined data in the border-out area of the optical disc;
An optical disc apparatus comprising: An optical disk device for recording data on an additionally recordable optical disk,
A photodetector having an inner peripheral detector and an outer peripheral detector for receiving reflected light from the optical disc;
A difference calculator for calculating a difference between the signal from the inner peripheral detector and the signal from the outer peripheral detector;
A comparator that outputs a land pre-pit signal included in the difference signal by comparing the difference signal from the difference calculator with a threshold value;
A controller that temporarily increases the threshold at the timing of starting border close of the border-out area of the optical disc;
An optical disc apparatus comprising:

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