JP2005196825A - Optical recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording apparatus which can perform correct recording operation by detecting a defect and an impact and performing proper processing in accordance with levels of the defect and the impact. <P>SOLUTION: The optical recording apparatus which performs proper processing in accordance with the magnitude of the defect by a means to detect an envelope signal from all light intensity signals of an optical disk; a means to compare the level of the detected envelope signal with at least a binary threshold; a means to detect a defect length to each threshold; a means to compare the detected defect length with a specified value, and generate a signal which carries out interrupt processing to recording operation if the detected defect length is longer than the specified value; and a means to store address information on an optical disk at the time of the generation of an interrupt signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical recording apparatus that records information on an optical disc.

In recent years, with the development of information-related technology, a large amount of information is exchanged via a communication line such as the Internet. In order to store and manage such a large amount of information, a small-sized and large-capacity optical disc has attracted attention as a recording medium.
In such an optical disc apparatus that records and reproduces information on an optical disc, when recording information, the semiconductor laser in the optical pickup is converted into convergent light by an optical system, and a desired laser spot is formed on the optical disc to obtain information. When the recording signal is reproduced, the recorded information is read by forming a laser spot on the recorded track and tracing the laser spot.

However, optical discs have a protective layer on the surface that protects the signal. However, depending on how the optical disc is handled, the protective layer on the surface may be damaged or a human fingerprint may be attached. There is a case.
Further, in the optical disk manufacturing process, air may be mixed into the resin, and black spots (black dots) may be formed in the protective layer. Such scratches and black spots not only affect the accurate tracing (tracking) of the laser spot with respect to the recording track, but also make it impossible to reproduce the signal.

In particular, if there are such scratches, fingerprints, and black spots on the optical disk on which the signal is recorded, the servo circuit that controls the trace of the laser spot will malfunction due to these effects, and it is completely different from the track that was originally trying to record. There was a problem that information was recorded on another track.
Such a defect is not only caused by scratches, fingerprints, and black spots on the optical disc, but also when an external impact is applied during the recording operation.

Therefore, in response to these problems, when a defect or the like is detected on the optical disc, the tracking servo is held during that time, or when an external impact is detected, the tracking servo gain is increased to reduce the influence on the disturbance. Techniques that make it possible have been proposed.
In addition, when the information recording operation is performed using the above technique, at least a part of the reflected light on the optical disk by the laser light irradiated for information recording is detected, and the information recording operation is abnormal due to the reflected light. In addition, a technique has been proposed in which information is recorded again in other sectors adjacent to the sector in which an abnormality is detected (see, for example, Patent Document 1).
JP 11-175975 A

However, originally, in order to realize a stable recording operation, for example, regarding a defect, it is necessary to divide the recording operation as follows according to the size of the defect.
In other words, 1) defects having a small size can be normally recorded / reproduced, so there is no problem even if the presence of the defect is ignored. Therefore, when a defect is detected, it can be processed by holding the tracking servo.

2) For a medium size defect, the recording operation can be performed normally, but an error may occur during reproduction after recording. Therefore, when a medium-sized defect is detected, it is necessary to re-record by changing the corresponding recording position.
3) For a large size defect, the off-track amount of the laser spot becomes large and the recording operation may become abnormal. Therefore, the recording operation should be stopped immediately.

However, since the conventional optical recording apparatus has only one defect detection unit, there is a problem that among the above, 2) and 3) cannot be particularly distinguished. Therefore, for example, when a defect is detected at the threshold level in 2), information may be recorded on an adjacent track when a large size defect occurs.
If a defect is detected at the threshold level in 3) and the recording operation is set to stop when this threshold is exceeded, recording on the adjacent track can be prevented, but the presence of a medium-sized defect can be prevented. It cannot be detected during recording.
Therefore, in order to solve this problem, it is necessary to perform reproduction after recording and check whether or not an error has occurred. However, when such processing is performed, the time until the recording operation is completed including these processing times increases. There was a problem.

On the other hand, for external impacts, as with defects, it is necessary to divide the recording operation according to the magnitude of the impact as follows.
That is, 1) Since a small impact can be normally recorded / reproduced, the recording operation may be performed ignoring the impact.
2) For a moderate impact, it is necessary to set the tracking servo gain higher than usual while the impact is detected so as to withstand the impact.
3) For large impacts, the off-track amount increases and the recording operation may become abnormal, so the recording operation should be stopped immediately.

  However, in the conventional optical recording apparatus, since there is only one shock detection unit, the above 1) to 3) cannot be distinguished. Therefore, for example, when a defect is detected at the threshold level in 2), information may be recorded on the adjacent track when a large impact occurs.

If a defect is detected at the threshold level in 3) and this threshold is exceeded, the recording operation is set to be stopped so that recording on an adjacent track when a large impact occurs can be prevented. When this shock occurs, the tracking servo gain cannot be increased to withstand the shock. For this reason, when a moderate impact occurs, the off-track amount increases, and recording may occur on adjacent tracks.
Further, as shown in FIG. 3, after the defect detection is completed, the tracking error signal is temporarily greatly disturbed, thereby generating a large off-track. Therefore, there is a case where this portion where no impact is actually applied is erroneously detected as an impact.

  Accordingly, the present invention has been made in view of the above-described problems, and an optical recording apparatus that realizes a correct recording operation by detecting defects and impacts and performing appropriate processing according to the level. The purpose is to provide.

The present invention proposes the following means in order to solve the above-described problems.
The invention according to claim 1 is an envelope signal detection means for detecting an envelope signal from a total light quantity signal of an optical disc, an envelope level comparison means for comparing the level of the detected envelope signal with at least a binary threshold, A defect length detecting means for detecting a defect length with respect to a threshold value of the threshold, and comparing the detected defect length with a specified value, and generating a signal for interrupting the recording operation when the detected defect length is longer than the specified value And an address information storage means for storing address information on the optical disc when the interrupt signal is generated.

  According to the present invention, the envelope signal is detected from the total light quantity signal of the optical disc by the operation of the envelope signal detecting means. The detected envelope signal is input to the envelope level comparison means, and the level is detected with respect to at least two threshold values. Next, the defect length for each threshold is detected by the operation of the defect length detection means, and each detected defect length is compared with the specified value by the operation of the interrupt signal generating means, and the detected defect length is set to the specified value. When the time is longer, a signal for interrupting the recording operation is generated. When an interrupt signal is generated, the address information on the optical disk where the interrupt signal is generated is stored in the address information storage means. Therefore, when the width and depth of the defect are detected and the width and depth of the defect are within a range that affects the correct recording operation, the recording operation is interrupted.

  According to a second aspect of the present invention, in the optical recording apparatus according to the first aspect, the means for detecting a tracking error signal associated with an impact is compared with the level of the detected tracking error signal with at least a binary threshold value. From the first and second tracking error level comparing means, the servo gain switching means for switching the tracking servo gain based on the output signal of the first tracking error level comparing means, and the first tracking error level comparing means And a recording operation stopping means for stopping the recording operation based on the output signal of the second tracking error level comparing means having a large value.

  According to the present invention, the tracking error signal associated with the impact is detected by the operation of the tracking error signal detecting means. The detected tracking error signal is input to the first and second tracking error level comparing means and compared with the respective threshold values. As a result, when the level of the input tracking error signal exceeds the threshold of the first tracking error level comparison means, the tracking servo gain is switched and exceeds the threshold of the second tracking error level comparison means. In that case, the recording operation is stopped.

  The invention according to claim 3 is the optical recording apparatus according to claim 1 or 2, wherein the envelope level exceeds all threshold values and each detected defect length is longer than a specified value. An optical recording apparatus has been proposed in which the recording operation is stopped.

  According to the present invention, when the envelope level exceeds all threshold values and the detected defect length is longer than the specified value, that is, for a defect having a deep depth and a wide width, the recording operation is stopped. As the amount of off-track increases, it is possible to avoid a situation where information is recorded on an adjacent track.

  According to a fourth aspect of the present invention, in the optical recording apparatus according to the second and third aspects, a first threshold value in the envelope level comparing means and a second threshold value having a value larger than the first threshold value And a signal switching means for outputting a signal when the envelope signal is larger than the first threshold value and smaller than the second threshold value, and delay generation for delaying the output signal of the signal switching means And a logic circuit for generating a logical product of the negative logic signal of the output signal of the delay generating means and the output signal of the second tracking error level comparing means, and supplying the generated signal to the recording operation stopping means An optical recording apparatus characterized by having:

  According to the present invention, by the operation of the signal switching means, the comparison result between the first threshold value in the envelope level comparison means and the second threshold value having a value larger than the first threshold value is input, and the envelope signal is the first value. A signal is output when it is larger than the second threshold and smaller than the second threshold. This signal is input to a delay generator, added with a desired delay, and converted into a negative logic signal. The negative logic signal and the output signal of the second tracking error level comparing means are input to the logic circuit, and the output signal of the logic circuit is supplied to the recording operation stopping means. Therefore, the output signal of the second tracking error level comparison means becomes invalid while the delay generator has an output signal, so that the recording operation stop means malfunctions due to the disturbance of the tracking error signal generated after passing the defect. Can be prevented.

According to the present invention, since the envelope signal level is detected with a plurality of threshold values and the defect length is detected, the detection of the defect that should replace the recording sector during recording and the detection of the defect that should stop the recording operation simultaneously. There is an effect that can be done.
Also, for external impacts, the level of the tracking error signal is detected with a plurality of thresholds, so that it is possible to simultaneously detect the impact that should be withstood by increasing the tracking servo gain and the impact that should stop the recording operation during recording. effective.
Furthermore, since the means for masking the disturbance of the tracking error signal that occurs when the defect passes is provided, there is an effect that malfunction can be prevented with respect to impact detection.

  Hereinafter, an optical recording apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 1, an optical recording apparatus according to an embodiment of the present invention includes an optical disc 1, an optical pickup 2, an APC (APC: Auto Power Control) 3, an RF amplifier 4, a servo circuit 5, and a signal. A processing circuit 6, a CPU (Central Processing Unit) 7, and a driver IC 8 are provided.

  The optical disc 1 is a recording medium on which information can be recorded, reproduced, and erased by a semiconductor laser, and examples thereof include a CD-R, a CD-RW, a DVD-R, and a DVD-RW. The optical pickup 2 includes a laser light source such as a laser diode (not shown), an objective lens driven by a collimator lens, a focus actuator or a tracking actuator, an optical component such as a polarization beam splitter, a cylindrical lens, and A, B, C, and D. Are divided into four regions, and a four-divided or two-divided photodetector (PD) for converting light into an electric signal, a front monitor diode for monitoring laser output during recording and reproduction, and the like are provided. The APC 3 is a control block for monitoring the current from the front monitor diode in the optical pickup 2 and controlling the emission power of the semiconductor laser to a desired value.

  The RF amplifier 4 detects the reflected light from the optical disc 1, calculates the amount of reflected light from the detected reflected light, generates an RF signal indicating the total amount of reflected light to each region of the four-divided PD, and optical pickup 2 is generated by the astigmatism method, and a tracking error signal (TE) that is a signal that detects a track shift of the irradiation laser of the optical pickup 2 is detected. Is generated by the push-pull method. The servo circuit 5 generates a focus drive signal (FODRV) and a tracking drive signal (TRDRV) based on the FE and TE generated by the RF amplifier 4. Further, a defect detection unit and an impact detection unit, which will be described later, are provided, and the tracking servo is appropriately controlled according to the level of the defect or the impact.

  The signal processing circuit 6 inputs an EFM signal generated from the RF signal at the time of reproduction and processes data, and includes a PLL circuit (not shown) to control the rotation of the spindle motor. The CPU 7 controls the entire apparatus based on a control program stored in a ROM (ROM: Read Only Memory) or the like. In this embodiment, the recording operation is continued, the servo output is held, or the recording operation is stopped based on the detection results of the defect detection unit and the impact detection unit.

  The driver IC 8 receives the focus drive signal (FODRV), the tracking drive signal (TRDRV), or the spindle control signal generated in the signal processing circuit 6 and amplifies them to a desired magnitude, then the focus actuator, tracking Supply to actuator or spindle motor. Further, the feed motor drive signal generated from the tracking drive signal (TRDRV) is amplified to a desired magnitude and then supplied to the feed motor.

  As shown in FIG. 2, the defect detection unit and the impact detection unit include low pass filters (LPF-1, LPF-2) 11a, 11b, level comparators 12a, 12b, 22a, 22b, a defect length measuring device 13a, 13b, pulse length comparators 14a and 14b, bandpass filters (BPF-1, BPF-2) 21a and 21b, a switch 23, a delay generator 24, a servo gain switch 25, and a driver drive signal The generator 26, the servo output hold unit 27, an AND circuit 28, and a condition setting unit 29 are configured.

  The low-pass filters (LPF-1, LPF-2) 11a and 11b receive a total light amount signal (hereinafter referred to as an RF signal) and extract an envelope signal. The level comparators 12a and 12b compare the level of the envelope signal extracted by the low-pass filters (LPF-1, LPF-2) 11a and 11b with a predetermined threshold value, and the result is low level or high level 2. Output as a value signal.

  The defect length measuring devices 13a and 13b receive the output signals of the level comparators 12a and 12b, and measure the pulse length using a timer or the like, thereby determining the length of the defect for each threshold value of the level comparators 12a and 12b. taking measurement. The pulse length comparators 14a and 14b compare the measured defect length with a predetermined threshold value in the defect length measuring devices 13a and 13b, and output the result as a binary signal of low level and high level.

  The bandpass filters (BPF-1, BPF-2) 21a and 21b receive the tracking error signal and extract the tracking error signal within the response frequency of the tracking actuator in the optical pickup. The pass bands of the bandpass filters (BPF-1, BPF-2) 21a, 21b are several kHz. The level comparators 22a and 22b compare the level of the tracking error signal extracted by the bandpass filters (BPF-1 and BPF-2) 21a and 21b with a predetermined threshold value, and compare the result with the low level and high level. Is output as a binary signal.

  The switch 23 receives the output signals of the two level comparators 12a and 12b in the defect detector, and outputs when the level comparator 12a having a small threshold value to be set is at a high level and the level comparator 12b is at a low level. The signal is output to the servo output hold unit 27 and the delay generator 24. The delay generator 24 receives the signal from the switch 23 and adds a desired delay amount to this signal. Note that the delay amount is set to a time at which the disturbance of the tracking error signal that occurs after passing the defect occurs.

  The servo gain switch 25 receives the signal from the level comparator 22b, and outputs a signal for controlling the open loop gain of the tracking servo based on this input signal. The driver drive signal generator 26 receives the control signal from the servo gain switch 25 and controls the level of the tracking drive signal input to the driver IC 8 based on this signal. Further, the signal from the servo output hold unit 27 is input, the drive signal output to the driver IC 8 is switched to the reference potential, and the objective lens is held in the tracking direction.

  The servo output hold unit 27 receives the signal from the switch 23 and outputs a signal for holding the tracking servo to the driver drive signal generator 26 based on this signal. The AND circuit 28 inputs a signal obtained by inverting the output signal of the delay generator 24 and the output signal of the level comparator 22a, and outputs a logical product signal of these signals. The condition setting unit 29 receives signals from the pulse length comparator 14b and the AND circuit 28, and controls the recording stop unit based on these input signals.

Next, the operation of this embodiment will be described with reference to FIGS.
First, the state of each signal when the optical disk 1 has a defect will be described with reference to FIG. In the figure, an RF signal, a defect detection signal, a hold signal, a tracking error signal, and an impact detection signal are shown from the top. The RF signal is represented by a signal having a predetermined width, the upper level is when the laser light irradiated on the optical disk 1 is totally reflected, and the lower level is when the laser light irradiated on the optical disk 1 is refracted by the pits. This shows the case where the return light is reduced.

  If there is a defect in the optical disc 1, the laser light irradiated to the defect is diffusely reflected and the return light is greatly reduced. For this reason, the level of the RF signal is greatly reduced in the defect portion, and a part of the waveform of the RF signal is lost. Therefore, if the envelope signal of the RF signal is detected and monitored, the presence of the defect can be detected. In general, since the defect has a frequency lower than that of the RF signal, the defect can be accurately detected by passing the RF signal through a low-pass filter and comparing the level of the output signal with a predetermined threshold.

  By the way, there are defects of various sizes. In addition, when there is a defect, even if you try to secure tracking by tracking servo, the tracking error signal to make the tracking servo function normally is disturbed by the influence of the defect, so accurate tracking can not be expected Rather, when the size of the defect is small, opening the tracking servo loop has less influence on the signal reproduction operation and information recording operation.

  On the other hand, if the tracking servo loop is opened when the size of the defect is large, the off-track amount increases, and even if the tracking servo loop is closed after passing the defect, the objective in the optical disc 1 is completely different on the track. The lens may be displaced. Such a situation can be avoided by, for example, performing a retry operation in the case of signal reproduction, and starting the reproduction operation from the vicinity of the defect. This causes a problem such as overwriting information on a recorded track.

  FIG. 6 shows a tracking drive signal. This amplitude corresponds to the amount of eccentricity of the optical disc 1. If there is no eccentricity in the optical disc 1, even if the tracking servo is held for a considerable time, such a large off-track does not occur. However, when the eccentric amount of the optical disc 1 increases, the AC component of the tracking drive signal Since the inclination increases, off-track during holding becomes a problem even with a small defect. Even if the amount of eccentricity is not so large, even when the defect width is large, off-track at the time of holding becomes a problem. FIG. 5 shows the relationship between the amount of eccentricity of the optical disc 1 and the defect length in which the hold operation is allowed.

  Therefore, in this embodiment, two threshold values are provided for the level comparators 12a and 12b. FIG. 4 shows the relationship between the total light quantity signal (RF signal) during recording and the threshold value. When the envelope signal of the RF signal exceeds the threshold value −10, the output of the level comparator 12a is a high-level pulse signal. It becomes. This signal is input to the defect length measuring device 13a. When the pulse width of this input signal exceeds the threshold value of -11, a signal for interrupt processing is output to the CPU 7. The CPU 7 stores the sector number on the optical disk at this time, performs sector substitution processing at an appropriate time, and records information to be recorded in another sector again.

  Next, when the envelope signal of the RF signal exceeds the threshold value −20, the output of the level comparator 12b becomes a high level pulse signal. This signal is input to the defect length measuring device 13b, and when the pulse width of this input signal exceeds the threshold value −21, a signal for interrupt processing is output to the CPU 7 and the condition setting device 29. The condition setter 29 receives signals from the pulse length comparator 14b and the AND circuit 28, and outputs a logical sum of these signals.

  At this time, when a signal for interrupt processing is output, the recording stop unit immediately stops recording. On the other hand, the CPU 7 stores the sector number at this time, performs sector replacement processing at an appropriate time, and records this information again in another sector.

  The switch 23 receives the output signals of the level comparators 12a and 12b. When the level of the envelope signal of the RF signal is larger than the threshold 10 and smaller than the threshold 20, the output signal is sent to the servo output hold device 27, Output to the delay generator 24. Thereby, when the level of the envelope signal is larger than the threshold 10 and smaller than the threshold 20, the tracking servo is held.

  On the other hand, the impact detection unit sets the bandpass filter (BPF-1) and the threshold value −30 so that a large impact that causes the objective lens to be off-tracked can be detected. Then, the output of the AND circuit 28 that inputs this output and the inverted signal of the signal delayed by a desired time to the output signal of the switch 24 is input to the condition setter 29, and the level of the tracking error signal is the threshold 30. When the value is larger than that, the recording operation is stopped. Note that the switch 23, the delay generator 24, and the AND circuit 28 are provided in the preceding stage of the condition setting unit 29 because the tracking error signal generated after passing the defect is erroneously caused by an impact as shown in FIG. This is to prevent detection.

  Further, the impact detection unit sets a band pass filter (BPF-1) and a threshold value -30 in order to detect a moderate impact or less. Then, this output is input to the servo gain switch 25 to increase the tracking servo gain, thereby preventing the occurrence of off-track with respect to a moderate or lower impact.

  Therefore, according to the present embodiment, since at least two threshold values are provided for the defect and the external impact, appropriate processing according to the size of the defect and the magnitude of the impact can be executed.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the specific configuration is not limited to these embodiments, and includes design changes and the like within a scope not departing from the gist of the present invention. It is. For example, in this embodiment, the type of the optical disk is not mentioned, but CD-R, DVD-R, CD-RW, DVD-RW, and other forms of optical disks may be used.

  In the present embodiment, the defect detection and the impact detection have been described with respect to a configuration having two systems, such as a low-pass filter, a band-pass filter, a level comparator, and a defect length measuring device, respectively. You may integrate.

1 is a configuration diagram of an optical recording apparatus according to the present invention. It is a block diagram of a defect detection part and an impact detection part. It is the figure which showed the relationship between an envelope signal and a threshold value. It is the figure which showed the mode of each signal at the time of defect passage. . It is the figure which showed the relationship between the eccentric amount of an optical disk, and the allowable defect length. It is the figure which showed the relationship between a tracking drive signal and a defect.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Optical pick-up, 3 ... APC, 4 ... RF amplifier, 5 ... Servo circuit, 6 ... Signal processing circuit, 7 ... CPU, 8 ...・ Driver IC,
11a, 11b ... low pass filters (LPF-1, LPF-2), 12a, 12b, 22a, 22b ... level comparators, 13a, 13b ... defect length measuring instruments, 14a, 14b ... pulses Long comparators, 21a, 21b ... band pass filters (BPF-1, BPF-2), 23 ... switch, 24 ... delay generator, 25 ... servo gain switch, 26 ... Driver drive signal generator, 27 ... servo output hold device, 28 ... AND circuit, 29 ... condition setter.

Claims (4)

An envelope signal detecting means for detecting an envelope signal from the total light amount signal of the optical disc;
Envelope level comparison means for comparing the level of the detected envelope signal with at least a binary threshold value;
A defect length detection means for detecting a defect length for each of the threshold values;
An interrupt signal generating means for comparing the detected defect length with a specified value and generating a signal for interrupting the recording operation when the detected defect length is longer than the specified value;
An optical recording apparatus comprising: address information storage means for storing address information on the optical disk when the interrupt signal is generated. Means for detecting a tracking error signal associated with the impact;
First and second tracking error level comparison means for comparing the level of the detected tracking error signal with at least a binary threshold value;
Servo gain switching means for switching the tracking servo gain based on the output signal of the first tracking error level comparing means;
And a recording operation stopping means for stopping the recording operation based on an output signal of the second tracking error level comparing means having a value larger than that of the first tracking error level comparing means. 1. An optical recording apparatus described in 1.   3. The optical recording apparatus according to claim 1, wherein the recording operation is stopped when the envelope level exceeds all threshold values and each detected defect length is longer than a specified value. . The comparison result between the first threshold value in the envelope level comparison means and the second threshold value having a value larger than the first threshold value is input, and the envelope signal is larger than the first threshold value, and the second threshold value Signal switching means for outputting a signal when smaller than,
Delay generating means for delaying the output signal of the signal switching means;
A logic circuit that generates a logical product of the negative logic signal of the output signal of the delay generating means and the output signal of the second tracking error level comparing means, and supplies the generated signal to the recording operation stopping means. The optical recording apparatus according to claim 2 or 3, wherein

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