JP2006120256A - Optical disk device and defect processing method of optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device capable of reducing a reproduction error by suppressing a transient response of an AGC circuit, and to provide a defect processing method of the optical disk. <P>SOLUTION: In this method, when a defect signal is detected from an RF signal of an optical disk such an RF switch 2 is arranged so that the defect signal is applied to a high-pass filter during only the specified period when the detection signal is outputted. Thus, when an IN2 of the RF switch 2 is selected to apply the defect signal through the HPF1, the defect signal can be attenuated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc apparatus capable of reproducing a signal recorded on an optical disc and a defect processing method for processing a defect signal of the optical disc.

  In recent years, optical disc apparatuses that record and reproduce data on a Blu-ray Disc have appeared. According to the Blu-ray Disc, in addition to a blue-violet laser having a wavelength of 405 nm and an objective lens having a numerical aperture (NA) of 0.85, a disc structure having a light transmission protective layer thickness of 0.1 mm is adopted. Up to 27 GB of data can be recorded on one side of a rewritable phase change optical disk.

  In the case of DVD at 680 nm, the cover layer is thick, the laser wavelength is long, 680 nm, the beam diameter is large, etc., and it does not cause a significant adverse effect on fingerprints, scratches, dust, etc. on the disc. . However, since the recording density of a Blu-ray disc is about 5 times that of a DVD and the light transmission protective layer of the disc is about 1/7, it is easily affected by defects on the surface of the disc. Therefore, in order to increase the error correction capability of ECC (Error Correction Code), the size of one ECC block is increased to 64 KB, which is the same size as the RUB (Recording Unit Block) which is a recording / playback unit of a Blu-ray disc. . However, if there are defects such as unexpected large fingerprints or large scratches on the disk surface, the data will be lost, and this will reach 1/3 of 1 ECC part (1RUB), and 1RUB data will be corrupted. .

  Also, due to such a disk defect, errors due to PLL (Phase Locked Loop) lock-in time after recovering from the defect, DC fluctuation of the reproduction RF signal due to transient response of AGC (Automatic Gain Control), etc. are added. As a result, an ECC error may occur.

The cause of such a malfunction is a lack of data due to a disk defect, and as a countermeasure, the AGC circuit has conventionally reduced the signal level due to the lack of a signal due to a disk defect or contamination such as fingerprints. A method of compensating (absorbing) with a time constant or a cutoff frequency of an HPF (high pass filter) has been employed (see, for example, Patent Document 1).
JP 2002-123945 A (paragraph 0035, FIG. 4)

  By the way, in a reproduction system that handles binary data on a 680 nm optical disk, the AGC circuit is unnecessary because the binary comparison is hardly affected by the level of the reproduction RF signal. In comparison operation, the reproduction signal is subjected to QFB (Quantized Feedback) (so-called auto slicer) to suppress the fluctuation of the zero cross point.

  However, in order to achieve higher density recording like a Blu-ray disc, 1-7PP (parity pre-serve / prohibit) RMTR (Repeated Minimum Transition Runlength) is adopted and A / D conversion is performed. What is needed has appeared, and the AGC circuit has become necessary again in the reproduction circuit. This is to prevent the level of the RF signal from being too small with respect to the range of A / D conversion in order to minimize the S / N reduction in A / D conversion.

  However, when the AGC circuit is mounted on the reproducing circuit in this way, the frequency of the loop against the change from the unrecorded portion to the recorded portion, the recorded portion to the unrecorded portion on the disk, or the decrease or absence of the RF signal due to a large defect Response becomes a problem. In particular, a configuration is adopted in which an HPF is provided in front of the AGC, thereby removing the DC component. As described above, there is also a problem that an error is caused due to the transient response of the AGC by the HPF.

  In view of the circumstances as described above, an object of the present invention is to provide an optical disc apparatus and an optical disc defect processing method capable of suppressing a transient response of an AGC circuit and reducing a reproduction error.

  In order to achieve the above object, an optical disc apparatus according to the present invention includes an RF signal reproducing means for reproducing the signal as an RF signal using reflected light from the optical disc on which the signal is recorded, and a frequency lower than the frequency of the RF signal. Detecting means for detecting a defect signal included in the reproduced RF signal having a frequency and outputting the detection signal for a predetermined period; a high-pass filter for attenuating the defect signal and passing the RF signal; Switch means for switching so as to apply the defect signal to a high-pass filter for the predetermined period based on the output detection signal.

  In the present invention, when a defect signal is detected from the RF signal of the optical disc, there is provided switching means for applying the defect signal to the high-pass filter for a predetermined period during which the detection signal is output. Thereby, when a defect signal is input to the high-pass filter by selection of the switch means, the defect signal can be attenuated. Further, for example, when an AGC circuit is provided in the subsequent stage of this switch, it is preferable to provide a high-pass filter having an optimum cutoff frequency in order to suppress a transient response of the AGC circuit. The frequency of the defect signal is, for example, 50 KHz to 200 KHz.

  According to an aspect of the present invention, the predetermined period is a first period included in the period in which the defect signal is generated, and a period continuous from the end of the first period, The end of the period is a second period delayed from the end of the period in which the defect signal is generated. In the present invention, the high-pass filter is applied to the defect signal from the end of the actual defect signal until it is delayed, so that the DC component can be prevented from trailing at the last part of the defect signal. A transient response of the AGC circuit can be prevented.

  According to one form of this invention, it is preferable that the cut-off frequency of the said high-pass filter is 1.0 MHz-3.0 MHz.

  According to an aspect of the present invention, the optical disc apparatus further includes an AGC circuit that automatically controls the gain of the reflected light amount, and an AGC hold unit that applies an AGC hold to the AGC circuit for the predetermined period. As a result, the transient response of the AGC circuit can be further suppressed, and errors can be reduced.

  According to an aspect of the present invention, the optical disc apparatus may further include a PLL circuit that generates a clock from a synchronization signal recorded on the optical disc, and a PLL hold unit that performs a PLL hold only for the predetermined period. Good. This synchronization signal is a signal recorded on the optical disc at a predetermined interval.

  The defect processing method for an optical disc according to the present invention includes the step of reproducing the signal as an RF signal using reflected light from the optical disc on which the signal is recorded, and the reproduction having a frequency lower than the frequency of the RF signal. Detecting a defect signal included in the RF signal and outputting the detection signal for a predetermined period; and a high-pass filter for cutting the defect signal and passing the RF signal based on the output detection signal. Switching to apply only for the predetermined period.

  In the present invention, the defect signal is attenuated by switching such that the defect signal is applied to the high-pass filter only for a predetermined period in which the detection signal is output, and for example, a transient response of AGC can be suppressed.

  As described above, according to the present invention, the transient response of the AGC circuit can be suppressed and the reproduction error can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to an embodiment of the present invention.

  The optical disc apparatus 101 includes a spindle motor 103 that rotates and drives an optical disc 102 such as a DVD ± R / RW, a CD-R / RW, and a Blu-ray disc, an optical pickup 106 that includes a PD (photo detector) 104 and a laser light source 105, The optical pickup 106 is output from a feed motor 107 that moves the optical pickup 106 in the radial direction of the optical disk 102, the entire apparatus, a system controller 108 that performs individual control such as signal processing and servo control, and a PD (photo detector) 104 of the optical pickup 106. A preamplifier 109 that generates a focus error signal, a tracking error signal, and an RF signal based on various signals, a defect signal processing circuit 110 that suppresses DC fluctuation of a reproduced RF signal due to a defect on the disk surface, modulation and demodulation of the signal Addition of ECC, signal modulator / demodulator & ECC unit 111 for performing error correction processing based on ECC, servo control unit 112 for driving and controlling spindle motor 103 and feed motor 107, interface 113 for connecting external computer 130, D / A conversion , An audio / visual processing unit 115, an audio / visual signal input / output processing unit 116, and a laser control unit 117 for driving the laser light source 105.

  FIG. 2 is a block diagram showing a configuration of the defect signal processing circuit 110 shown in FIG. The defect signal processing circuit 110 is a sub HPF1 that divides the RF reproduction signal from the preamplifier 109 as it is and a signal that has passed through a high-pass filter composed of a capacitor C1 and a resistor R1, and the divided signals become IN1 and IN2. The main HPF 3 that removes the low frequency component generated by the rotation period of the disk, which is comprised of the RF switch 2, the capacitor C 2, and the resistor R 2 that are inputted and selects either one of the inputted signals, and included in the RF signal, and the medium AGC circuit 4 that automatically controls the signal level to a constant level so that it can be demodulated stably when there is a variation in the signal level, etc., suppresses intersymbol interference and enhances the high-frequency level to attenuate An equalizer 5, an A / D converter 6 for digitally converting an analog signal, Having a PLL circuit 11 which generates a clock based on a synchronization signal recorded at predetermined intervals on the disk 102. The defect signal processing circuit 110 also detects a defect from the RF reproduction signal, a defect detection circuit 7 for detecting the defect, a pulse of the defect detection signal detected by the defect detection circuit 7, and a recording position, that is, an address on the optical disk where the defect has occurred. A memory 8 for storing information, a memory controller 9 for controlling storage processing and read timing of the memory 8, and a processor 10 for reading address information from the memory 8 and for performing overall control of the defect signal processing circuit 110. Have.

  Defects caused by extremely low or extremely high reflectivity from the optical disk are caused by fingerprints or scratches, and these defects are mostly a part of one RUB. Therefore, the address information stored in the memory 8 may be address information of a defective RUB and time information until the defect with reference to a synchronization signal recorded for each RUB. . In general, on a Blu-ray optical disc 102, one sync signal and three address information are recorded for each RUB.

  The cut-off frequency fcs of the sub HPF 1 is set higher than the cut-off frequency fcm of the main HPF 3. The cut-off frequency fcs of the sub HPF 1 is set to a frequency that sufficiently passes 2T to 8T, which are RF signals of Blu-ray. For example, fcs is set to 1 MHz. When a Blu-ray double speed playback system is employed, fcs is set to 1 to 3 MHz. On the other hand, the cutoff frequency fcm of the main HPF 3 is set to a band that does not cause a data error, and is set to 33 to 66 KHz, for example.

  Based on the defect signal detected by the defect detection circuit 7, the processor 10 generates defect processing signals 21, 22 and 23 for the defect processing as described below, and the RF switch 2, the AGC circuit 4 and the PLL circuit. 11 respectively. Specifically, the defect processing signals 21, 22 and 23 are a switch pulse signal 21 for switching the RF switch 2, an AGC hold signal 22 for holding the gain of the AGC circuit 4, and a PLL for holding the PLL circuit 11, respectively. This is a hold signal 23. The PLL hold is realized, for example, by holding a voltage input to a VCO (voltage controlled oscillator) (not shown) in a state immediately before the PLL hold signal 23 is output.

  A rough reproduction operation of the optical disc apparatus 101 configured as described above will be described.

  The output of the RF signal reproduced by the preamplifier 109 is input to the sub HPF 1. When an appropriate RF reproduction signal is obtained, the RF switch 2 selects IN1 and inputs the output of HPF1. That is, the RF signal as it is is input. Then, the main HPF 3 removes unnecessary low frequency components and DC components, and an RF signal is supplied to the AGC circuit 4. In the AGC circuit 4, the RF signal is adjusted to a constant gain, the level of the high band that attenuates is increased in the equalizer 5, and digitized in the A / D converter 6 to extract data. In the PLL circuit 11, a clock signal is generated from the output of the A / D converter 6, and data demodulation and error correction are performed in the signal modulator / demodulator & ECC unit 111 based on the clock signal. When data is demodulated and error correction is performed, the data is supplied to an external computer via the interface 113, or converted into an analog signal by the D / A converter 114, and the audio / visual processing unit 115 reproduces video and audio. Or

  FIG. 3 is a waveform diagram for explaining the transient response of the AGC circuit after AGC hold in the prior art. As shown in FIG. 3A, if there are large scratches, fingerprints, or the like on the optical disc, a signal is generated that greatly reduces the reflectivity from the optical disc. That is, a defect signal that is greatly reduced in the RF reproduction signal is generated. In FIG. 3, the hatched portion is the RF high frequency signal. As shown in FIG. 3B, when this defect signal is passed through an LPF (low pass filter), the high frequency band is removed. When the level of the defect signal becomes lower than the threshold level TH in FIG. 3B, the defect detection signal D shown in FIG. 3C is generated. When the defect detection signal D is generated, an AGC hold is applied based on the defect detection signal D at the potential of A or B as shown in FIG. However, the detection signal D of the defect signal is delayed and turned on by setting the threshold value TH, and the detection signal D is turned off before the completion of the defect signal shown in FIG. For this reason, after the AGC hold in FIG. 3D is released, a transient response occurs in the AGC circuit during the period C in FIG. 3E (showing the output of the AGC circuit). Further, as described above, when a DC component is included in the AGC input, a transient response occurs. Usually, before the input of the AGC circuit, an HPF that removes a low-frequency component and a DC component due to the reflectance fluctuation that occurs in the rotation period of the disk is provided, so the AGC output signal is shown in FIG. The differential form is as follows.

  Although it is conceivable to set the threshold value TH high in order to detect the defect signal with high accuracy, if the threshold value TH is set high, it is not a large defect as shown in FIG. Since even a defect having a small error correction range is detected as a defect detection signal, processing is wasted. The optical disc apparatus 101 according to the present embodiment is intended to reduce the error as much as possible by eliminating the above-described AGC transient response.

  FIG. 4 shows an actual defect waveform. In each graph, reference numeral 31 denotes an output waveform of the AGC circuit, reference numeral 32 denotes a defect signal (preamplifier output), and reference numeral 33 denotes a defect detection signal (in FIGS. 4D and 4E, the LPF shown in FIG. 3B). Output). As shown in the figure, the output waveform 31 of the AGC has a differentiated form. 4 (a), (b) and (c), the defect shown in FIGS. 4 (d) and 4 (e) is a scratch that increases the reflectivity. It is. Such scratches are relatively narrow. That is, it is a relatively short time defect. Further, the defects shown in FIGS. 4C, 4D, and 4E are shallower than the defects shown in FIGS. 4A and 4B, and the decrease in the RF signal is small. Although the occurrence appears to be large, FIGS. 4A to 4E are all defects that lead to a large error.

  8 and 9 show waveforms of the HPF low frequency response, respectively. These are the output waveforms of the HPF normally input to the AGC circuit. FIG. 8 shows a step wave and FIG. 9 shows a sine wave. Reference numerals 34a and 44a are 20 μs wide pulse inputs, and reference numerals 35a and 45a are HPF responses to them. Reference numerals 34b and 44b are 1 μs wide pulse inputs, and reference numerals 35b and 45b are their HPF responses. As can be seen, when a low-frequency signal is passed through the HPF, an attenuation characteristic due to the time constant of the HPF occurs after the signal. This causes a transient response in the AGC circuit.

  FIG. 5 is a diagram showing signal waveforms of the defect processing according to the present embodiment. As shown in FIG. 5A, for example, when there is a defect signal of about 20 μs starting at the HS time and ending at the HE time, a threshold value is provided as in the case shown in FIG. 7 generates a defect detection signal D having a period shorter than 20 μs and outputs it to the processor 10 as shown in FIG. The processor 10 stores the address information on the optical disc 102 corresponding to the defect detection period in the memory 8 in association with the information of the defect detection period. In this case, the processor 10 may divide the reproduction clock (for example, 66 MHz) to about 10 MHz and write it in the memory 8. This is because the defect is from several μs, and an accuracy of about 0.1 μs is sufficient.

  When the defect detection signal D is detected, during normal playback, the processor 10 generates a defect processing signal F longer by x than the period of the defect detection signal D, as shown in FIG. The defect processing signal F (or a defect processing signal G described later) is a signal for improving the influence of the defect as described above, and is a signal output to the RF switch 2, the AGC circuit 4, and the PLL circuit 11, respectively. It is. This x is set so as to include the HE at the end of the defect signal shown in FIG. 5A, that is, the FE at the end of the defect processing signal F is the same as or after HE. This x may be 4 to 8 μs, for example. As a result, the defect processing period becomes longer. For example, if the AGC hold is performed only during the period of the defect processing signal F, the AGC transient response after the AGC hold is released can be suppressed. Thereby, errors can be reduced. Not only the AGC hold, but also a PLL hold or a switching process by the RF switch 2 as described later may be performed. Note that PLL hold is not performed for defect signals of 20 μs or less.

  On the other hand, even when the defect processing signal F shown in FIG. 5C is generated, when the ECC fails, the processor 10 performs control so that reproduction (retry) is performed again. Specifically, the processor 10 reads, for example, a read signal (not shown) for reproducing one block of the RUB including the defective portion based on the address information on the disc of the defective RUB stored in the memory 8. Further, the defect detection signal pulse R stored in the memory 8 is read from the memory 8. In this case, the read timing of the signal pulse R for the defect detection is set as follows based on time information or the like until the start of the defect (rise of the defect detection signal D) with reference to the synchronization signal. That is, the rising RS of the signal pulse R is set to be before the defect signal start time HS. Furthermore, as shown in FIG. 5E, the processor 10 generates a defect processing signal G that is earlier than the original defect detection signal D by y. This y is set so that the pulse of the defect processing signal G completely includes HS to HE. In FIG. 5, FE and GE are at the same timing, but they may be at different timings. Moreover, y may be 4 to 8 μs, for example. As a result, for example, an error improvement interval of about 6 μs can be increased, and ECC failure can be suppressed.

  Further, as shown in FIG. 6, the track pitch p of the Blu-ray disc is as narrow as 0.32 μm, and when there are defects 15, 16, 17 and 18 of several hundreds μm, the disc rotation period between adjacent tracks is Will be affected almost at the same timing. That is, if the track pitch p is sufficiently small with respect to the defect 15 or the like, it can be said that the defect shape for each track is almost similar regardless of the shape of the defect. Therefore, in continuous playback of CLV (Constant Linear Velocity), it becomes possible to use a defect signal before one rotation of the disk, and errors can be reduced even in normal playback (playback in which addresses continuously change). That is, once a defect signal is detected and its address is stored, it is possible to predict that a defect having substantially the same or similar shape is detected in the rotation period of the disk. By utilizing this fact, even if there is a large defect, no retry is required, continuous reproduction is possible, and unnecessary retry operations can be reduced. In this case, specifically, since the defect for each track is often similar, the error improvement interval is 6 ± X μs (X as shown in FIG. 7E) as compared to FIG. 5E. Is a value corresponding to the predicted shape of the defect).

  Next, the operation of the part related to the RF switch 2 will be described.

  The output of the preamplifier 109 is input to the sub HPF 1 shown in FIG. 2. As described above, when an appropriate RF reproduction signal is obtained, the RF switch 2 selects IN 1 and inputs the output of the HPF 1 is doing. That is, the RF signal as it is is input.

  On the other hand, when the defect signal as shown in FIG. 5A matches, the defect detection circuit 7 outputs the detection signal as shown in FIG. Based on this detection signal, the processor 10 generates a defect processing signal G at the time of retry, for example, a switch pulse, and outputs it to the RF switch 2 as shown in FIG. Then, the RF switch 2 inputs a defect signal to IN2. That is, the defect signal is passed through the high pass portion of the sub HPF 1. Thereby, the defect signal can be attenuated, and errors can be reduced.

  Further, the processor 10 may output not only the switch pulse signal 21 but also at least one of the AGC hold signal 22 and the PLL hold signal 23 in addition to the switch pulse signal 21.

  10 and 11 are waveform diagrams showing how the DC component is removed by the RF switch 2. Reference numeral 36 indicates a defect low frequency signal, reference numeral 37 indicates an output of the main HPF 3 when a signal is input to the IN 1 of the RF switch 2, and reference numeral 38 indicates an output of the high pass itself of the sub HPF 1 (signal input to the IN 2). ing. Reference numeral 39 denotes an output of the RF switch 2 when the switch pulse of the reference numeral 41 is delayed from the defect signal and is input to the RF switch 2, and IN2 is selected by the RF switch 2. The outputs of the main HPF 3 are respectively shown. In order to make the operation easy to understand, the input of the switch pulse 41 is delayed with respect to the defect signal 36 in this way. In an actual circuit, as shown in FIG. 3C, FIG. 5B, and the like, the defect detection is delayed with respect to the defect signal, so that it is closer to reality and easy to understand. Further, the switch pulse 41 shown in FIG. 11 is turned on later than that shown in FIG. 10 and turned off earlier than when the defect signal 36 ends.

  From FIGS. 10 and 11, it can be seen that the effect of the main HPF 3 is eliminated by switching to IN2. As described above, when there is a defect signal, the sub HPF 1 having a time constant smaller than the time constant of the main HPF 3 is switched before the input of the main HPF 3, that is, before the input of the AGC circuit 4. Transient response can be suppressed and errors can be reduced.

  FIGS. 12 and 13 are diagrams showing actual waveforms of defect responses, respectively (a), (b), and (c). FIG. 12 is related to the present embodiment, and FIG. is there. Reference numeral 42a is a defect signal, reference numeral 43a is a signal obtained by applying an AGC hold to the output of the AGC circuit 4 when switched to IN2 of the RF switch through the sub HPF 1, and reference numeral 44a is a defect detection signal. The same applies to FIG. 13, and reference numeral 43 b indicates the output of the AGC circuit when the AGC hold is not applied without the sub HPF 1 and the RF switch 2. 12 and 13, (a), (b), and (c) are different in defect type and width.

  In FIG. 13, a DC fluctuation is seen in the AGC output waveform 43b at the end of the defect signal, but it can be seen that the DC fluctuation is improved in FIG. In FIG. 13 (b), it seems that there is no DC fluctuation, because the DC level has risen once at the portion indicated by reference numeral 43b-1 and there is no RF signal at the position where DC changes. is there. In this case, errors are reduced.

  FIG. 14, FIG. 15 and FIG. 16 are graphs showing measurement results when measuring a LDC (Long Distance Code) error by reproducing a defective RUB as shown in FIG. 12 and FIG. The horizontal axis indicates the number of measurements, and the vertical axis indicates the number of LDC errors. Note that LDC is an error correction method used in Blu-ray Discs, and is a technique in which the parity of Reed-Solomon codes is lengthened to improve the correction capability.

  FIG. 14 is a graph when the defect type is (1) or (2) in the figure. As can be seen from FIG. 14, the error is greatly improved in the case of the AGC hold and the case of the AGC hold + switching process compared to the case of no AGC hold.

  FIG. 15 is a graph in the case where the defect type is (1) or (2) in the same manner as in FIG. In FIG. 15, the RF gate is a process that blocks a signal when a defect is detected. As can be seen from FIG. 15, the same improvement effect is obtained in all three cases. From the results shown in FIG. 15, assuming that there are 3000 ECC failures per RUB, up to 6 AGC holds, 1 on average without AGC hold, and 6 on AGC hold + switching are allowed.

  FIG. 16 is a graph when the defect type is the type shown in (3) in the figure. The AGC hold is more stable than when it is not. Compared to the case of AGC hold, the AGC hold + switching process stably halves. From the results shown in FIG. 16, assuming that there are 3000 failures of ECC per RUB, up to 4 in AGC hold, 7 in average without AGC hold, and 9 in AGC hold + switching processing are allowed.

  From FIG. 14, FIG. 15 and FIG. 16, it can be seen that the combination processing such as AGC hold + switching processing reduces the error most.

1 is a block diagram showing a configuration of an optical disc apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of a defect signal processing circuit shown in FIG. 1. FIG. 6 is a waveform diagram for explaining a transient response of an AGC circuit after AGC hold in the related art. An actual defect waveform is shown. It is a figure which shows the signal waveform of the defect process which concerns on this Embodiment. It is a schematic diagram showing the relationship between the defect on the disk surface and the track pitch. It is a figure which shows the signal waveform in the case of performing the defect process shown in FIG. It is a figure which shows the waveform (step wave input) of the low frequency response of HPF. It is a figure which shows the waveform (sine wave input) of the low frequency response of HPF. It is a wave form diagram which shows the mode of DC component removal by RF switch. It is a wave form diagram which shows the mode of DC component removal by RF switch (when switch pulse timing is changed). It is an actual waveform diagram of the response of the defect according to the present embodiment. It is an actual waveform diagram of the response of the defect in the prior art. It is a graph which shows a measurement result when measuring LDC error (the 1). It is a graph which shows a measurement result when measuring LDC error (the 2). It is a graph which shows a measurement result when measuring LDC error (the 3). It is a figure which shows the actual circuit example of RF switch.

Explanation of symbols

1 Sub HPF
2 RF switch 3 Main HPF
4 AGC circuit 7 Defect detection circuit 8 Memory 10 Processor 11 PLL circuit 101 Optical disk device 102 Optical disk 110 Defect signal processing circuit

Claims (6)

RF signal reproducing means for reproducing the signal as an RF signal by using reflected light from the optical disc on which the signal is recorded;
Detecting means for detecting a defect signal included in the reproduced RF signal having a frequency lower than the frequency of the RF signal and outputting a detection signal for a predetermined period;
A high-pass filter that attenuates the defect signal and passes the RF signal;
An optical disc apparatus comprising: switch means for switching so that the defect signal is applied to a high-pass filter for the predetermined period based on the output detection signal. The optical disc apparatus according to claim 1,
The predetermined period is a first period included in a period in which the defect signal is generated and a period continuous from the end of the first period, and the defect signal is generated at the end of the period. An optical disc apparatus characterized by comprising a second period delayed from the end of the period during which the recording is performed. The optical disc apparatus according to claim 1,
An optical disc apparatus characterized in that a cutoff frequency of the high pass filter is 1.0 MHz to 3.0 MHz. The optical disc apparatus according to claim 1,
An AGC circuit for automatically controlling the gain of the reflected light amount;
An optical disc apparatus further comprising: AGC hold means for applying an AGC hold to the AGC circuit for the predetermined period. The optical disc apparatus according to claim 1,
A PLL circuit that generates a clock from a synchronization signal recorded on the optical disc;
The optical disc apparatus further comprises PLL hold means for applying a PLL hold for the predetermined period. Replaying the signal as an RF signal using reflected light from the optical disc on which the signal is recorded;
Detecting a defect signal included in the reproduced RF signal having a frequency lower than the frequency of the RF signal and outputting a detection signal for a predetermined period;
And a step of switching the high-pass filter that cuts the defect signal and passes the RF signal based on the output detection signal so as to be applied only for the predetermined period. .

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