JP2005339742A - Optical disk device and tracking control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device in which servo is not disturbed, and also provide a tracking control method. <P>SOLUTION: The optical disk device reads the information of an optical disk which has a fixed address discontinuous to tracks in its write-once information recording region. In addition, the device is provided with; a position detecting means 109 which detects the positional information of the fixed address; a quasi synchronization generating means 108 which generates the quasi positional information for the interpolation of the fixed address; a comparing means 108 which compares the positional information detected by the position detecting means with the output of the quasi synchronization generating means; a quasi synchronization generating means 108 which generates a signal to which a time base correction is made to the quasi synchronization generating means based on the result of the output by the comparing means; and a switching means 108 which switches the control of the tracking servo of the fixed address by the output of the quasi synchronization generating means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc apparatus and a tracking control method.

  In a DVD-RAM disc, there is a fixed address called CAPA in addition to a recordable logical address in a recording area for recording information. This fixed address is non-rewritable information that is physically formed by a disk stamper when an optical disk is formed, and is formed at a position offset from the recording track.

  This CAPA is the same discontinuity information as the scratches formed on the optical disc, and is a factor that hinders stable servo operation for the disc servo (particularly tracking servo) of the optical disc apparatus that reads the optical disc.

For reference, Cited Document 1 that describes a track search method that is resistant to external obstacles of the optical disk is cited as a reference.
Japanese Patent Laid-Open No. 7-334853

  FIG. 4A shows a plan view in which a CAPA is formed on a track of such a DVD-RAM disc. FIG. 4B shows a reproduction RF signal (Trace-A) when reproducing a DVD-RAM disk when there is no defect such as a scratch, and a tracking error signal at that time. FIG. 4C shows a reproduction RF signal (Trace-B) when reproducing a DVD-RAM disc when there is a defect, a tracking error signal, a CAPA position detection signal, a CAPA processing gate signal at that time, A CAPA pseudo synchronization signal and a pseudo CAPA processing gate signal are shown.

  As shown in FIG. 4A, a scratch 10 is formed on this disc, and a recording offset in a partial track direction by overwriting or the like as shown in a reproduction RF signal (Trace-B) in FIG. 4C. When this occurs (hereinafter referred to as a defective portion), the signal quality for position detection is degraded and the detection operation cannot be performed accurately.

  In this case, since the servo processing peculiar to CAPA cannot be performed, the operation of the entire disk servo becomes unstable.

  As a means to compensate for the missed detection (detection error) of the CAPA position information, when information is continuously read from the disk (hereinafter referred to as sequential reproduction), the position information is determined from the continuity (periodicity) of the detection result of the CAPA position information. A method of predicting and complementing the position of the missing portion (defective portion) of the image (shown in the pseudo CAPA processing gate signal in FIG. 4C) is conceivable.

  However, since it is necessary to check the periodicity of the detection result in this method, it is necessary to read information continuously to some extent, and there is a problem that errors in the interpolation position are accumulated when the interpolation portion is long. Further, it does not hold during a discontinuous reading operation such as a search (hereinafter referred to as a seek operation).

  For this reason, the continuity for complementing the CAPA position information cannot be confirmed, such as when a defective portion occurs immediately after the end of seeking, and the CAPA process cannot be performed, and the disk servo becomes unstable.

  As shown in (1) (Trace-C) of FIG. 3, when the target address A is accessed by the normal seek operation, the seek is performed immediately before the target address, and then the information of the address A is read. At this time, when a defective portion (recorded with an offset with respect to the track center of the disk) occurs at the address A, the tracking servo follows the offset recording portion, so that the trace of the CAPA portion is also offset.

  In the structure of the DVD-RAM disc, the CAPA is offset in both directions with respect to the track center of the disc. When the recording track is offset, the CAPA cannot be traced depending on the degree of the offset. To do. Therefore, the position cannot be detected, the tracking servo is disturbed, and there is a problem that the recorded data (logical address) immediately after the missing portion cannot be read (shown in (3) reproduction RF signal in FIG. 3). In this state, the operation cannot be converged particularly when the above-described defective portion occurs in a short-distance seek operation such as one track.

  As a means to compensate for this omission of detection, a method is considered in which a seek target address is set to a small address before a certain margin with respect to the data reading address, and after the seek operation, the remaining part is predicted and interpolated by sequential reproduction. It is done.

  However, in this method, depending on the length to be interpolated, an interpolation position shift occurs due to the accumulated error of the predicted interpolation position, which eventually leads to servo disturbance.

    Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide an optical disc apparatus and a tracking control method free from servo disturbance.

To achieve the above object, the present invention provides an optical disc apparatus capable of reading information on an optical disc having a discontinuous fixed address with respect to a track in an additionally recordable information recording area,
Position detecting means for detecting position information of the fixed address;
Pseudo-synchronization creating means for pseudo-creating position information for interpolation of the fixed address;
Comparing means for comparing the position information detected by the position detecting means with the output of the pseudo-synchronizing means;
Pseudo-synchronization creating means for creating a signal that has been subjected to time axis correction of the pseudo-synchronization creating means based on the output result of the comparing means;
There is provided an optical disc apparatus comprising switching means for switching the tracking servo control of the fixed address according to the output of the pseudo-synchronization creating means.

In addition, for an optical disc having a fixed address that is discontinuous with respect to a track in an additionally recordable information recording area,
Detecting position information of the fixed address;
Artificially creating position information for interpolation of the fixed address;
Compare the location information of the fixed address and the pseudo-created location information,
Based on the result of the comparison, create a signal with the time axis corrected,
There is provided a tracking control method, wherein switching of tracking servo control of the fixed address is switched by a signal obtained by correcting the time axis.

  In the present invention, when a defective part occurs immediately after the end of the seek operation, the seek target address is expanded before and after the target address, the CAPA before and after the target address is detected, and the positions of pseudo-sync and CAPA detection interpolated in the stable part ( (Phase) information is corrected, and position information of the defective portion is interpolated by pseudo-synchronization with the time axis corrected, thereby improving search accuracy and ensuring servo continuity.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment, Various selections can be used.

  FIG. 1 is a block diagram of a disk device according to an embodiment of the present invention.

  This optical disc apparatus includes a support means 106 for supporting an optical disc 101 having a digital data recording layer (information recording surface) 103 for recording digital data, a disc motor 102 for rotationally driving the optical disc 101, and an optical disc 101. An optical pickup 105 for condensing light on the digital data recording layer 103 and a light source (incorporated in the pickup 105) for irradiating the optical disc 101 with light through the optical pickup 105 are provided.

  This disk device can record digital data on the digital data recording layer 103 by light irradiation from a light source.

  Further, the pickup 105 is provided with a position sensor 109, and this position sensor 109 can also detect the CAPA of the optical disc 101. The pickup 105 can be driven in a tangential direction with respect to the optical disc 101 by a feed motor 110.

  The feed motor 110 is driven and controlled by a feed drive circuit 111. In the pickup 105, a laser as a light source is driven and controlled by a laser driving circuit 112 and a focus driving circuit 113, and an objective lens is focus-controlled.

  In addition, the rotational speed of the disk motor 102 is controlled by a disk motor drive circuit 114.

  The pickup 105 is connected to the signal processing circuit 115 and reads data from the digital data recording layer 103 of the optical disc 101 or writes data to the digital data recording layer 103.

  The focus drive circuit 113, laser drive circuit 112, feed drive circuit 111, disk motor drive circuit 114, and signal processing circuit 115 are controlled by the controller 108.

  The controller 108 is connected to the external host computer 116 via the I / F 115.

  The pickup 105 and the controller 108 can record and reproduce information. For this reason, a laser drive circuit 112, a front monitor, and a focus / tracking actuator are provided, and the reflected light of the optical disc 101 is detected, and a focus error, tracking error, RF signal, and the like can be detected.

  The pickup 105 converts the rotation of the feed motor 110 into a radial movement of the optical disc 101 by a lead screw and rack system. Here, the feed motor 110 uses a stepping motor.

  Next, the tracking control method of the present invention will be described using the flowchart of FIG. 2 and the signal waveform of FIG.

  The target address A is accessed by the seek operation (step (1) in FIG. 2). Next, the seek operation is performed with the seek target set to an address slightly smaller than the address A (step (2) in FIG. 2). Next, CAPA detection is performed by the CAPA detection means (step (3) in FIG. 2), and if stable, the tracking servo is turned on (step (4) in FIG. 2). Next, the data at address A is read (step (5) in FIG. 2). finish.

  Here, when a defect is confirmed near address A in the CAPA detection shown in step (3) and the CAPA detection becomes unstable, the counter is set to n = 1 (step (6) in FIG. 2), and the seek target address is set. Is changed to A-α (step (7) in FIG. 2). Here, α is an arbitrary value.

  Next, CAPA is detected at address A-α which is a new seek destination (step (8) in FIG. 2). If a defect is confirmed again and becomes unstable, the counter is incremented by one (FIG. 2). In step (9), the seek target address is changed to A-2α (step (7) in FIG. 2). Steps (9), (7), and (8) are repeated to search for a point where CAPA can be detected stably.

  When the defect is not confirmed by the CAPA detection in step (8) and becomes stable, the position (phase) information of the pseudo-synchronization generating means at the address A-α is synchronized with the position information detected in step (8). (Step (10) in FIG. 2).

  Next, the counter is set to m = 1 (step (11) in FIG. 2), and the seek target address is newly set to A + β (step (12) in FIG. 2) Next, the seek operation is performed, and the CAPA is performed at the address A + β. (Step (13) in FIG. 2) If a defect is confirmed and becomes unstable by the CAPA detection in Step (13), the counter is incremented by 1 (Step 14 in FIG. 2), and the seek target address is set to “ Change to A + 2β ″ (step (12) in FIG. 2). Steps (14), (12), and (13) are repeated to search for a point where CAPA can be detected stably.

  Next, when the defect is not confirmed by the CAPA detection in step (13) and becomes stable, it is detected by the position (phase) information of the pseudo-synchronization generating means at the address A + β and the CAPA detection in step (13). The position information is compared (step (15) in FIG. 2). Next, the oscillation cycle (phase) of the pseudo-synchronization generating means is corrected from the comparison result of step (15) (step (16) in FIG. 2).

  A Gate pulse for performing CAPA special processing is created from the output of the pseudo-synchronization generating means that has corrected the oscillation period (step (17) in FIG. 2), and the address is obtained with interpolation of missing CAPA position information near address A. Seek to A (address (18) in FIG. 2). Thereafter, the tracking servo is turned on (step (4) in FIG. 2) and the address A information is read (step (5) in FIG. 2).

  For the CAPA detection in steps (3), (8), and (13), common detection means or independent detection means may be used.

  Next, the contents described with reference to the flowchart of FIG. 2 will be described below with reference to FIG.

  As shown in Trace-C in FIG. 3, when a track recorded in the vicinity of the address A as a seek destination is recorded with an offset with respect to the center of the disk track, the tracking servo follows the recording track. Therefore, the trace of the CAPA portion also passes with an offset. In the structure of the DVD-RAM disc, the CAPA is offset in both directions with respect to the track center of the disc. When the recording track is offset, the CAPA cannot be traced depending on the offset amount. (Reproduced RF signal (3) in FIG. 3).

  For this reason, a part where the CAPA position information cannot be detected occurs, and the tracking servo is not stable in the part where the CAPA position information cannot be detected, so the recorded information (logical address part) immediately after CAPA cannot be read (reproduced RF signal (3) in FIG. 3). And tracking error (4)).

  When a defect is confirmed in the vicinity of the address A, as shown in Trace-D, the seek destination is changed to the address A-α and a seek operation is performed. If no defect is confirmed near the address A-α, the position (phase) information of the pseudo synchronization signal (8) at the address A-α is synchronized with the position information of the CAPA position detection result (7). At this time, the period T1 of the CAPA position detection result and the period of the pseudo synchronization signal are T1 '.

  Next, a seek destination is newly set to address A + β and a seek operation is performed. If no defect is found near the address A + β, it is confirmed that the period of the CAPA position detection result is T1, and the position (phase) information of the pseudo synchronization signal (8) at the address A + β and the CAPA position detection result The positional information of (7) is compared to detect a positional information shift. Based on the positional information shift (9) described above, an error between the period T1 and the period T1 ′ is corrected, and a CAPA processing gate pulse (10) inserted between the address A−α and the address A + β is created. In the state where the missing CAPA position information in the vicinity is interpolated, the seek to the address A is performed, and then the information at the address A is read.

1 is a block diagram of an optical disc apparatus according to an embodiment of the present invention. The flowchart for demonstrating the tracking control method concerning embodiment of this invention. The signal waveform diagram for demonstrating the tracking control method concerning embodiment of this invention. The signal waveform diagram for demonstrating the tracking control method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Optical disk 102 ... Disc motor 103 ... Information recording surface 105 ... Pick-up 106 ... Support means 108 ... Controller 109 ... Position sensor 110 ... Feed motor 111 ... Feed drive circuit 112 ... Laser drive circuit 113 ... Focus drive circuit 114 ... Disc motor drive circuit 115 ... Interface 116 ... Host computer

Claims (2)

An optical disc apparatus capable of reading information on an optical disc having a discontinuous fixed address with respect to a track in an additionally recordable information recording area,
Position detecting means for detecting position information of the fixed address;
Pseudo-synchronization creating means for pseudo-creating position information for interpolation of the fixed address;
Comparing means for comparing the position information detected by the position detecting means with the output of the pseudo-synchronizing means;
Pseudo-synchronization creating means for creating a signal that has been subjected to time axis correction of the pseudo-synchronization creating means based on the output result of the comparing means;
An optical disc apparatus comprising switching means for switching tracking servo control of the fixed address according to an output of the pseudo-synchronization creating means. For an optical disc having a fixed address that is discontinuous with respect to a track in an additionally recordable information recording area,
Detecting position information of the fixed address;
Artificially creating position information for interpolation of the fixed address;
Compare the position information of the fixed address and the pseudo-created position information,
Based on the result of the comparison, create a signal with the time axis corrected,
A tracking control method, wherein switching of tracking servo control of the fixed address is switched by a signal obtained by correcting the time axis.

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