JP4725403B2 - Optical disc recording / reproducing apparatus - Google Patents

Description

  The present invention relates to an optical disk recording / reproducing apparatus that uses an optical disk such as a CD, a DVD, and a BD (Blue-ray), and more particularly to an optical disk recording / reproducing apparatus that detects a servo deviation during recording and reproduction.

  When a servo shift occurs due to vibration or shock that exceeds the servo bandwidth due to external force during recording or playback of an optical disk recording / playback device, data is recorded on adjacent tracks, especially during recording. Destruction occurs. Therefore, there is provided means for constantly monitoring servo deviation and stopping recording when servo deviation is detected during recording.

As one method of detecting servo deviation, conventionally, a track error signal is binarized, the number of edges of the binarized signal is counted within a certain time, and if the count value is a certain number or more, track deviation is detected. A method has been devised in which it is determined that a recording has occurred and a recording stop command is supplied to the controller to stop recording.
Japanese Patent Laid-Open No. 01-66826 Japanese Patent Laid-Open No. 03-35430 JP 2002-25081 A JP-A-61-282639 JP 61-42742 A JP 63-213130 A

  However, in the conventional example, when scratches, dust, fingerprints, etc. are attached to the optical disc and the component is superimposed on the track error signal, a signal other than the original track error signal appears in the binarized signal. There was a problem of false detection as if it had happened.

  In view of the above circumstances, the present invention detects the number of edges of a binarized signal and the edge interval time, and the characteristics of the number of edges of the binarized signal and the edge interval time generated by the original track deviation, scratches, dust, Paying attention to the difference between the number of edges of the binarized signal and the edge interval time due to the attachment of fingerprints, etc., it can prevent the occurrence of recording stop, playback stop, etc. due to erroneous detection of track deviation, recording operation An object of the present invention is to provide an optical disc recording / reproducing apparatus capable of stabilizing the reproducing operation.

To achieve the above object, the inventions of claim 1, recording data on the optical disk using a light beam, the optical disk recording and reproducing apparatus for reproducing,
An optical pickup that outputs a detection signal based on reflected light when the optical disk is irradiated with the light beam;
A track error signal generator for generating a track error signal based on the detection signal;
A binarized signal generator that binarizes the track error signal and outputs a binarized signal;
An edge number counter that counts the number of edges that are the number of rising edges and falling edges of the binarized signal within a predetermined time during recording or reproduction of data with respect to the optical disc;
An edge interval time detector that measures an edge interval time value, which is the time interval at which the edge occurs,
A memory for storing the latest plurality of edge interval time values;
A plurality of edge intervals in which the number of edges is equal to or greater than a first threshold value, a total value of edge interval time values stored in the memory is less than a second threshold value, and stored in the memory If the ratio of the maximum value to the minimum value of the time value is less than the third threshold value, and determine the constant means you determined that off-track has occurred,
An optical disc recording / reproducing apparatus comprising:

Further, the inventions of claim 2, keep an optical disk recording and reproducing apparatus according to claim 1,
Wherein the first threshold value, it records the time values to the optical disk, an optical disk recording and reproducing apparatus characterized that you have been set to a value smaller than the value at the time of reproduction to the optical disc.

  In the optical disk recording / reproducing apparatus according to the present invention, the binarized signal disturbance generated when scratches, dust, etc. are attached to the optical disk, and the binarized signal disturbance generated due to the actual track deviation are accurately identified. In addition, it is possible to stabilize the track deviation detection process so that erroneous recording stop and reproduction stop do not occur.

<Description of identification principle>
First, prior to the detailed description of the optical disk recording / reproducing apparatus according to the present invention, the identification principle of the optical disk recording / reproducing apparatus according to the present invention will be described.

  In order to distinguish between when scratches, dust, etc. are attached to the optical disk and when true track misalignment occurs, the present inventor tracks that are generated when scratches, dust, etc. are attached to the optical disk. The error signal and the track error signal when a real track deviation occurred were observed in detail.

  As a result, when scratches, dust, etc. are attached to the optical disc, the track error signal fluctuates randomly over a relatively long period of time as shown in FIG. On the other hand, when the track deviation occurs, as shown in FIG. 5A, it is found that after the track error signal becomes flat, there is a tendency that the frequency gradually increases from a low frequency.

Then, when the track error binarized signal obtained by binarizing these track error signals is examined, when scratches, dust, etc. are attached to the optical disc, as shown in FIG. with edges the number of the track error binary signal at "800 s" is a certain value or more, scratches, dust, due to the adhesion of a fingerprint or the like, since there is a long interval data is disturbed, continuous N intervals, e.g. Since the total time of the edge interval times of the three sections becomes a certain value or more, and the edge interval time is random and has no regularity, the ratio indicating the variation in the edge interval times of the latest N sections (ratio = maximum) (Value / minimum value) was found to be a certain value or more.

On the other hand, when the track deviation occurs, as shown in FIG. 5B, the number of edges of the track error binarized signal at a certain time, for example, “800 μs” becomes a certain value or more , and the track deviation occurs. Since it immediately passes the wrong track after it occurs, the total time of the edge interval times of consecutive N intervals, for example, 3 intervals, becomes less than a certain value, and the edge interval times are aligned to some extent, Recently ratio showing the variation of each edge interval time of N intervals (ratio = maximum value / minimum value) was found to be below a certain value.

  Therefore, the present inventor uses the number of edges of the binarized signal obtained by binarizing the track error signal for a certain time, for example, “800 μs” as a first determination criterion for determining whether or not track deviation has occurred. As a second criterion, whether the total time obtained by summing the edge interval times of consecutive N sections, for example, three sections, is less than a certain value, As a third determination criterion, whether or not the ratio (ratio = maximum value / minimum value) indicating the variation of the edge interval times in the latest N sections is less than a certain value is adopted.

  Then, when the actual track error signal was examined using the first determination criterion, the second determination criterion, and the third determination criterion, the track was shifted from the case where scratches, dust, etc. were attached to the optical disc. It was possible to accurately discriminate from the case where this occurred.

<< Configuration of Embodiment >>
FIG. 1 is a block diagram showing an embodiment of an optical disk recording / reproducing apparatus according to the present invention using the above-described identification principle.

  The optical disk recording / reproducing apparatus 1 shown in this figure uses a spindle unit 3 that rotates an optical recording medium 2 such as an optical disk so that the linear velocity is constant, an autofocus function, an autotracking function, and the like on the optical recording medium 2. The servo unit 4 that irradiates the track with a laser beam and records and reproduces the data, and the track error signal output from the servo unit 4 is binarized to obtain the actual edge value, the edge interval time value, etc. The operation of the spindle unit 3 and the servo unit 4 is controlled based on the output of the track deviation detection unit 5, the output of the operation panel, the track deviation detection unit 5 and the like. And a controller 6.

  Then, while rotating the optical recording medium 2 so that the linear velocity is constant by the spindle unit 3, the servo unit 4 spot-irradiates the designated track (recording / reproducing target track) on the optical recording medium 2. In addition, while recording and reproducing data, the track deviation detection unit 5 determines whether or not a track deviation has occurred. When a track deviation has occurred, the recording / reproducing operation is stopped and erroneous recording is performed. Prevent processing, playback stop, etc.

  The spindle unit 3 generates a drive voltage corresponding to the rotational speed of the optical recording medium 2, the position of the recording / reproduction target track, and the drive voltage output from the motor driver 8, and receives the drive voltage output from the motor driver 8. And a spindle motor 7 for rotating the optical recording medium 2 so that the linear velocity becomes constant.

  The servo unit 4 combines one main laser beam generated by a light source such as a semiconductor laser element and two sub-laser beams by a half mirror and emits the reflected light to the recording medium 2 while taking in a plurality of reflected lights. From an optical pickup 9 that outputs a detection signal, a focus error signal generation unit (FE signal generation unit) 10 that generates a focus error signal based on each detection signal output from the optical pickup 9, and a focus error signal generation unit 10 Based on the output focus error signal, an objective lens driving actuator 11 attached to the optical pickup 9 is driven, and a focus actuator driver (focus ACT driver) 12 for condensing the combined beam on the recording / reproducing target track; Based on the detection signal output from -A track error signal generation unit (TE signal generation unit) 13 for generating a signal, and the objective lens drive actuator 11 is driven based on the track error signal output from the track error signal generation unit 13 to be combined with a recording / reproduction target track. And a track actuator driver (track ACT driver) 14 for tracking the beam.

  The track deviation detection unit 5 includes a comparator and the like, and is output from the binarized signal generator 15 and the binarized signal generator 15 that binarizes the track error signal output from the track error signal generator 13. The number of rising edges and falling edges of the binarized signal is counted to generate an edge number counter 16 and a reference clock signal having a frequency sufficiently higher than the edge interval time. Using the reference clock unit 17 and the reference clock signal output from the reference clock unit 17, the edge interval time of the binarized signal output from the binarized signal generation unit 15 is measured, and the edge interval time value (count) Edge interval time detection unit 18 that generates (value), and N edge interval time values output from the edge interval time detection unit 18 (for example, 3 or more), the number of edge values output from the edge number counter 16 and a plurality of edge interval time values stored in the memory 19, the first determination criterion, the second And a CPU 20 that detects track deviation by applying the determination criterion 3 and the third determination criterion.

<< Operation of Embodiment >>
Next, the operation of the optical disc recording / reproducing apparatus 1 will be described with reference to the block diagram shown in FIG. 1, the flowchart shown in FIG. 2, and the timing chart shown in FIG.

  First, when a user operates the operation panel of the optical disc recording / reproducing apparatus 1 to input a recording operation instruction or a reproducing operation instruction, the spindle unit 3 rotates the optical recording medium 2 so that the linear velocity is constant. While being driven, the servo unit 4 is turned on to start emission of a combined beam obtained by combining the main laser light and the sub laser light, and focus servo and track servo are started.

  Then, after the focus servo and track servo pull-in operations are stabilized, the controller 6 is controlled by the controller 6 to start the data recording operation or the data reproducing operation on the optical recording medium 2.

Further, in parallel with this operation, the binary signal generator 15 of the off-track detection unit 5, are detected zero crossing the track error signal output from the servo unit 4, the binary signal is generated. The generated binarized signal is counted by the edge number counter 16, and the edge number value after the counter reset is updated. In addition, the edge interval time value is detected by the reference clock unit 17 and the edge interval time detection unit 18, and the edge interval time values for N intervals (for example, the latest three intervals or more) are stored in the memory 19.

  Further, in parallel with this operation, as shown in the flowchart of FIG. 2, the CPU 20 of the track deviation detection unit 5 performs a first determination process using the first determination criterion. In the first determination process, the edge number value obtained by the edge number counter unit 16 is registered in advance at a predetermined time, for example, every “800 μs”, for example, “10 at the time of reproduction”. It is checked whether there are less than “book” and less than “5” at the time of recording. The reason why the number of edges is changed during recording and during reproduction is that the sensitivity may be slightly reduced during reproduction, but there is a possibility of erroneous recording during recording.

If the edge number is less than the threshold value, it is determined that there is no scratch, dust, fingerprint or the like on the recording medium 2 and no track deviation has occurred, and the edge number counter 16 is reset (step S1).

Further, Der edge present value is above the threshold lever (step S1), and when the first discrimination process is performed, CPU 20 by scratches on the optical recording medium 2, dust, adhesion of fingerprints, etc., or off-track has occurred The edge interval time values for the N sections stored in the memory 19 are read out, and the total time of the edge interval time values is calculated (step S2). Thereafter, a second determination process using the second determination criterion is performed, and it is checked whether or not the total time is less than a second threshold value (for example, 300 μs) set in advance.

Then, if the total time is equal to or larger than the threshold, the CPU 20, scratch the optical recording medium 2, dust, it is determined that the noise generated by the attachment of fingerprints or the like, the edge number counter 16 is reset (Step S3) .

If the total time is less than the threshold (step S3), the CPU 20 extracts the edge interval time value that is the maximum value and the edge interval time value that is the minimum value from among the edge interval time values. Then, a ratio (ratio = maximum value / minimum value) indicating the variation of each edge interval time value is calculated (steps S4 and S5), and a third determination process using the third determination criterion is performed. Te ratio is checked whether it is less than the third threshold value which is set in advance, if the ratio is equal to or greater than the threshold, it is determined scratches on the optical recording medium 2, dust, and noise generated by the adhesion of fingerprints, etc. Thus, the edge number counter 16 is reset (step S6).

  Also, as shown in FIG. 3A, if a track deviation occurs and the edge actual value is larger than the threshold value as shown in FIG. 3C (step S1), as shown in FIG. 3D. When the first determination processing is performed, the CPU 20 determines that scratches, dust, fingerprints, or the like have occurred on the optical recording medium 2 or the track has shifted, and as shown in FIG. After each edge interval time value for N sections stored in the memory 19 is read and the total time of each edge interval time value is calculated (step S2), a second determination process is performed, It is checked whether the total time is less than a preset threshold.

  If the total time is less than the threshold (step S3), the CPU 20 extracts the edge interval time value that is the maximum value and the edge interval time value that is the minimum value from among the edge interval time values. Then, a ratio (ratio = maximum value / minimum value) indicating the variation of each edge interval time value is calculated (steps S4 and S5). Then, a third determination process is performed to check whether the ratio is less than a preset threshold value.

  Here, if the ratio is less than the threshold (step S6), the CPU 20 determines that a track deviation has occurred, and if recording is in progress, a stop command is generated as shown in FIG. The servo unit 4 is turned off, focus servo processing and track servo processing are stopped (step S7), a recording stop command is generated and supplied to the controller 6, and the recording operation is stopped (step S8).

  If it is determined that the ratio is less than the threshold value and playback is in progress, a stop command is generated by the CPU 20, the servo unit 4 is temporarily turned off, and focus servo processing and track servo processing are performed. After being temporarily stopped, the servo unit 4 is started to be turned on.

<< Effects of the Embodiment >>
As described above, in this embodiment, the edge actual value and the edge interval time value of the binarized signal obtained by binarizing the track error signal output from the servo unit 4 are obtained, and the edge actual value and the edge interval time are obtained. Since it is determined whether or not the value satisfies the first determination criterion, the second determination criterion, and the third determination criterion, and based on the determination result, it is determined whether or not a track deviation has occurred. Stable track deviation detection processing by accurately discriminating between binarized signal disturbance caused by scratches, dust, etc. on the optical disc and binarized signal disturbance caused by true track deviation It is possible to prevent erroneous recording stop and playback stop from occurring.

<< Other embodiments >>
In the above-described embodiment, as the first determination criterion for determining whether or not track deviation has occurred, the number of edges of the track error binarized signal at a certain time, for example, “800 μs” becomes larger than a certain value. As a second criterion, whether or not the total time obtained by summing the edge interval times of consecutive N sections, for example, three sections, is less than a certain value, for example, less than 300 μs, is employed. As a criterion, whether or not the ratio (ratio = maximum value / minimum value) indicating the variation of each edge interval time in the latest N sections is less than a certain value is adopted, but similar identification accuracy can be obtained. If there is a determination criterion that can be used, any one of the first determination criterion to the third determination criterion may be replaced with another determination criterion.

  For example, the second criterion is used when determining whether the recording medium 2 is scratched, dirty, or out of track by using the period length in which the binarized signal is disturbed. A value corresponding to the period length in which the binarized signal is disturbed, for example, the time required for the number of edges to return to a normal value starting from the time when the number of edges of the binarized signal becomes an abnormal value (or The time it took to start tracking pull-in for the wrong track, etc.), and determine whether or not there is a track deviation based on whether this time is longer or shorter than a preset threshold. May be.

1 is a block diagram showing an example of an optical disc recording / reproducing apparatus according to the present invention. 2 is a flowchart showing an operation example when a track deviation is detected in the optical disc recording / reproducing apparatus shown in FIG. 2 is a timing chart when a track deviation occurs in the optical disc recording / reproducing apparatus shown in FIG. FIG. 6 is a waveform diagram showing an example of a track error signal and a binarized signal when passing through a spot where scratches, dust, fingerprints, etc. are attached in a general optical disc recording / reproducing apparatus. FIG. 6 is a waveform diagram showing an example of a track error signal, a binarized signal of the track error signal, and a recording stop signal when a track deviation occurs in a general optical disc recording / reproducing apparatus.

Explanation of symbols

1: optical disk recording / reproducing apparatus 2: optical recording medium 3: spindle unit 4: servo unit 5: track deviation detection unit 6: controller 7: spindle motor 8: motor driver 8: optical pickup 10: focus error signal generator 11: objective Lens drive actuator 12: Focus actuator driver 13: Track error signal generator 14: Track actuator driver 15: Binary signal generator 16: Edge counter (edge count / edge interval time detector)
17: Reference clock unit 18: Edge interval time detection unit (number of edges / edge interval time detection unit)
19: Memory (number of edges / edge interval time detection unit)
20: CPU (track deviation determination unit)

Claims (2)

In an optical disc recording / reproducing apparatus that records and reproduces data with respect to an optical disc using a beam light,
An optical pickup that outputs a detection signal based on reflected light when the optical disk is irradiated with the light beam;
A track error signal generator for generating a track error signal based on the detection signal;
A binarized signal generator that binarizes the track error signal and outputs a binarized signal;
An edge number counter that counts the number of edges that are the number of rising edges and falling edges of the binarized signal within a predetermined time during recording or reproduction of data with respect to the optical disc;
An edge interval time detector that measures an edge interval time value, which is the time interval at which the edge occurs,
A memory for storing the latest plurality of edge interval time values;
A plurality of edge intervals in which the number of edges is equal to or greater than a first threshold value, a total value of edge interval time values stored in the memory is less than a second threshold value, and stored in the memory If the ratio of the maximum value to the minimum value of the time value is less than the third threshold value, and determine the constant means you determined that off-track has occurred,
An optical disc recording / reproducing apparatus comprising: Wherein the first threshold value, it records the time values to the optical disc, the optical disc recording and reproducing according to claim 1, characterized that you have been set to a value smaller than the value at the time of reproduction to the optical disk apparatus.

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