JP2007026582A - Optical disk recording/reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent tracking and access stability from being deteriorated by superposition of the reproducing signal of an ID area in a tracking error signal and a track cross signal in high speed reproduction of a DVD-RAM disk. <P>SOLUTION: Superposition on a tracking error signal is eliminated through filtering of high sampling processing, and superposition on a tracking cross signal is eliminated through time-based filtering. A program operated in a conventional first processing circuit is operated as it is when a second processing circuit for executing high sampling processing is added, thereby development efficiency is improved, and development period is shortened. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an optical disc recording / reproducing apparatus for recording / reproducing a DVDRAM disc.

In the reproduction of a DVDRAM disk having an ID area composed of emboss marks at a position shifted by a half track with respect to the data track consisting of lands and grooves, the superimposition of the ID area signal on the tracking error signal increases the stability of the servo. In the past, it has been a challenge to maintain.
The invention described in Japanese Patent Application No. 10-338723 is a technique widely used as a countermeasure method, and its contents will be described as a conventional example.

  FIG. 6 is a block diagram of a tracking servo section of a conventional optical disc recording / reproducing apparatus.

  101 is a head amplifier that converts reflected light from the optical disk into an electrical signal, 102 is an AD converter that converts the head amplifier output into a digital signal, and 103 is an error signal that performs arithmetic processing on the digital signal to generate a tracking error signal The generation means 104 is a hold control means for performing a hold process on the tracking error signal and outputting it, 105 is a servo filter means for generating a pickup drive signal from the hold processed signal, and 106 is driven by the pickup drive signal The pickup is a pickup, and the feedback light beam is formed by displacing the focal position of the reproduction light beam in the radial direction of the disk and detecting the reflected light that changes as a result by the head amplifier 101. Reference numeral 107 denotes ID area detecting means for detecting the ID area from the reproduction signal detected by the head amplifier 101 and outputting a detection signal to control the hold control means 104.

  The hold control means 104 outputs the input signal as it is when the ID area is not detected by the ID area detection means 107, and outputs zero when the ID area is detected.

  The servo filter 105 is a PID control filter, and has three processing systems of an integral term, a proportional term, and a derivative term. When the input becomes zero by the hold control means 104, the calculation result of the proportional term and the derivative term. Since the value becomes zero and only the calculation result of the integral term is output, the output signal is held.

7A and 7B show operation waveforms of the conventional optical disc recording / reproducing apparatus. FIG. 7A shows an output waveform of the error signal generating means 103, FIG. 7B shows an output waveform of the servo filter 105, and FIG. 7C shows an ID area. This is a detection signal.
In FIG. 7, the period indicated by α shows a state in which the ID region signal is superimposed on the tracking error signal. When the hold process is not performed, the waveform β indicated by the broken line in FIG. Is output and makes tracking servo unstable.

  When the hold process is performed, the waveform γ indicated by the solid line in FIG. 5B is output as a drive signal, and therefore, a drive output that shakes the pickup is not output, so that the tracking servo can be kept stable.

  As a method for detecting an ID region, as described in Japanese Patent Application No. 10-338723, when tracking servo is applied, a tracking error signal having a level near zero is greatly increased by superimposing the ID region signal. There are a method of detecting the shaking, a method of predicting the timing at which the ID area is reproduced by counting the wobble signal recorded on the optical disc and measuring the period from the ID area to the ID area.

  On the other hand, FIG. 8 is a block diagram of a track cross signal generator of a conventional optical disc recording / reproducing apparatus.

  121 is a head amplifier, 122 is an error signal generating means, 123 is a binarizing means, 124 is a time axis filter, and 125 is a track cross processing means.

  The time axis filter 4 monitors the input binarized signal, and after confirming that it has become “H” or “L” for a certain time or more, the output is switched to “H” or “L”. By this operation, the time axis filter removes a pulse having a duration of a certain time or less from the input binarized signal and outputs it.

  The track cross processing means 125 performs processing related to the track cross signal, such as counting the number of track crosses, generating a brake pulse for ending the jump operation, and detecting a jump speed by measuring the track cross signal period during the jump operation. Is.

  FIG. 9 is a diagram showing operation waveforms of the track cross generation unit. (A) is an output of the error signal generation unit 122, and ID region signals are superimposed at four points α, β, γ, and δ. Yes. (B) is the output of the binarizing means 123, (c) is the output of the time axis filter 124, and the threshold of the time axis filter 124 is set to the same time as the ID region duration.

In the waveform (c), superimposed noise can be removed in all cases from α to δ, and the stability of the speed control in the jump operation can be improved.
JP-A-10-338723

However, in the conventional configuration, when the tracking servo is not operating, a method of detecting that the tracking error signal is greatly shaken due to the superimposition of the ID area signal, or the wobble signal recorded on the optical disk is counted. Both the method for predicting the timing at which the ID area is reproduced by measuring the period from the ID area to the ID area cannot be used as a means for detecting the ID area. In this operation mode, it is impossible to prevent the ID area signal from being superimposed on the tracking error signal, and the tracking servo pull-in must be left unstable.
In particular, when performing high-speed recording / reproduction such as 16-times speed, the gain of the high frequency of the servo filter is set high, so that the drive signal is greatly shaken by the superimposition of the ID area signal. The impact was also significant.
Further, in the jump operation, if the threshold value is increased to the same as the duration of the ID area as described in the conventional example in order to completely remove the noise of the track cross signal due to the superimposition of the ID area signal, the delay of the track cross signal is caused. There is a problem that the timing of brake pulse generation at the end of the jump is delayed and the jump operation becomes unstable.

In order to solve the above problems, the optical disk recording / reproducing apparatus of the present invention operates to superimpose the ID region signal on the tracking error signal with a sampling period of 3 usec or less, and the ID region signal superimposing frequency in DVDRAM 16 × speed reproduction is 220 KHz. It is removed by a high-frequency attenuation filter that can maintain a high attenuation rate up to the high frequency range.
Further, by binarizing after removing the high frequency of the tracking error signal, even if the setting time of the time axis filter is shortened, the superimposed noise due to the ID area signal to the track cross signal is effectively removed.
In addition, in order to realize the high-frequency attenuation filter, high-speed arithmetic processing for a sampling period of 3 usec or less is required, but a processing circuit that executes only servo processing at high speed is added and executed in the original processing circuit. The influence on control processing other than servo processing is minimized.

The optical disk recording / reproducing apparatus of the present invention is a servo program for performing servo processing of the optical disk recording / reproducing apparatus, and the servo program has a high-frequency attenuation filter function having an attenuation factor of 8 dB and 20 dB or more at 100 KHz and 200 KHz, respectively. The attenuation factor of the high-frequency attenuation filter can be increased to 20 dB or higher up to a high frequency of 220 kHz or higher, which is the ID region signal superimposing frequency at 16 × speed reproduction of DVDRAM, to a tracking error signal at the time of high-speed recording / reproduction of DVDRAM ID region signal superimposition can be effectively removed, and therefore, during an operation mode such as jumping and tracking pull-in where servo hold processing based on prediction of ID region reproduction timing becomes impossible, ID region signal superimposition The servo There is an effect that it is possible to avoid the deterioration of qualitative.
Further, in the servo signal processing circuit of the optical disc recording / reproducing apparatus, AD conversion means, tracking error signal calculation means for calculating a tracking error signal from the conversion result of the AD conversion section, a low-pass filter, and the low-pass filter The time axis filter comprises: binarization means for generating a track cross signal by binarizing the output of the signal; and time axis filter means for removing a pulse having a width less than a set width from the input track cross signal. The threshold value set in the means is set to ½ or more of the ID area duration at the linear velocity for recording / reproducing the DVDRAM disc,
As a result of effectively removing the noise caused by the superimposition of the ID area signal, stable speed control can be achieved by suppressing fluctuations in the track cross signal period during jumping, and jump operation can be stabilized and accuracy can be improved. By suppressing the delay time of the cross signal to be small, there is an effect that it is possible to prevent a delay in the timing of the brake pulse at the end of the jump and realize stable tracking pull-in.

  Further, a processing circuit 1 capable of operating a program 1a for performing servo processing with a cycle Ts and a program 1b for performing other control processing, a first memory storing only the program 1b, and processing equivalent to the program 1a are performed. The program 1b of the core 1 is configured at a low speed even in a high speed recording / reproducing apparatus by being constituted by the processing circuit 2 in which the program 2a executed at the cycle Ts / N operates and the second memory storing the program 2a. Since the program for the recording / reproducing apparatus can be used, and the program 1a is merely inoperative or deleted, it can be easily corrected and has less risk. Therefore, it is possible to reduce the development period and the development personnel.

  In addition, when developing a high-speed recording / reproducing apparatus, the circuit evaluation of the high-speed recording / reproducing apparatus can be performed using the programs 1a and 1b for the low-speed recording / reproducing apparatus, so that the development period and development personnel can be reduced. Even in the high-speed recording / reproducing servo system to which the processing circuit 2 is added, the low-speed recording / reproducing servo system can be realized by operating the program 1a. There is an effect that a low-speed recording / reproducing apparatus with no increase in power can be realized by using the same processing circuit as the high-speed recording / reproducing apparatus.

  Further, a processing circuit 1 capable of operating a program 1a for performing servo processing with a cycle Ts and a program 1b for performing other control processing, a first memory storing only the program 1b, and processing equivalent to the program 1a are performed. A processing circuit 2 that operates a program 2a executed at a cycle Ts / N, a second memory that stores the program 2a, and a high-frequency attenuation filter that has an attenuation rate of 8 dB and 20 dB or more at 100 KHz and 200 KHz, respectively. By providing the function, the program 1b of the core 1 can use the program for the low-speed recording / reproducing apparatus even in the high-speed recording / reproducing apparatus, and the program 1a can be easily modified because it is not operated or deleted. Since there are few risks, it is possible to reduce the development period and development personnel.In addition, when developing a high-speed recording / reproducing apparatus, the circuit evaluation of the high-speed recording / reproducing apparatus can be performed using the programs 1a and 1b for the low-speed recording / reproducing apparatus, so that the development period and development personnel can be reduced. Even in the high-speed recording / reproducing servo system to which the processing circuit 2 is added, the low-speed recording / reproducing servo system can be realized by operating the program 1a. A low-speed recording / reproducing apparatus with no increase in power can be realized by using the same processing circuit as that of the high-speed recording / reproducing apparatus, and at the same time, a high ID region signal superposition frequency of 220 KHz or higher at the time of 16-times reproduction of DVDRAM. Since the attenuation rate of the high-frequency attenuation filter can be increased to 20 dB or more up to the frequency range, it is possible to effectively eliminate the superimposition of the ID region signal on the tracking error signal during high-speed recording / reproduction of DVDRAM. Servo hold processing based on prediction of ID area playback timing is impossible and tracking pull-in is impossible In operating mode, there is an effect that it is possible to avoid a decrease in the servo stability due ID area signal superimposing.

  Further, a processing circuit 1 capable of operating a program 1a for performing servo processing with a cycle Ts and a program 1b for performing other control processing, a first memory storing only the program 1b, and processing equivalent to the program 1a are performed. A tracking circuit that calculates a tracking error signal from a conversion result of a reproduction signal input to the processing circuit 2, a second memory that stores the program 2a, and a second memory that stores the program 2a. A signal calculation means, a low-pass filter, a binarization means for generating a track cross signal by binarizing the output of the low-pass filter, and a pulse having a width equal to or smaller than a set width from the input track cross signal And a threshold value set in the time axis filter means. The program 1b of the core 1 can use the program for the low-speed recording / reproducing apparatus even in the high-speed recording / reproducing apparatus, because it is set to 1/2 or more of the CAPA area duration in the DVDRAM disk reproducing double speed. Since the program 1a is simply inoperative or deleted, it can be easily corrected and has less risk. Therefore, the development period and the development personnel can be reduced. In addition, when developing a high-speed recording / reproducing apparatus, the circuit evaluation of the high-speed recording / reproducing apparatus can be performed using the programs 1a and 1b for the low-speed recording / reproducing apparatus, so that the development period and development personnel can be reduced. Even in the high-speed recording / reproducing servo system to which the processing circuit 2 is added, the low-speed recording / reproducing servo system can be realized by operating the program 1a. As a result of realizing a low-speed recording / reproducing apparatus with no increase in power by using the same processing circuit as that of the high-speed recording / reproducing apparatus, noise due to superimposition of ID area signals can be effectively removed, resulting in a track cross signal period during jump Stable speed control can be achieved by suppressing fluctuations in the speed, stabilization of jump operation and improvement of accuracy can be realized, and the delay time of the track cross signal can be reduced to prevent delay of brake pulse timing at the end of jump. Thus, there is an effect that stable tracking pull-in can be realized.

  Further, a processing circuit 1 capable of operating a program 1a for performing servo processing with a cycle Ts and a program 1b for performing other control processing, a first memory storing only the program 1b, and processing equivalent to the program 1a are performed. A tracking circuit that calculates a tracking error signal from the AD conversion result of a reproduction signal input to the processing circuit 2, a second memory storing the program 2a, and a reproduction signal input to the processing circuit 2 with a cycle Ts / N An error signal calculation means, a low-pass filter, a binarization means for generating a track cross signal by binarizing the output of the low-pass filter, and a set width or less from the input track cross signal And a time axis filter means for removing pulses, and the program 2a has 100 KHz and 2 A high-frequency attenuation filter function having an attenuation factor of 8 dB and 20 dB or more at 0 KHz, respectively, and the threshold value set in the time axis filter means is 1/2 or more of the ID area duration at the linear velocity for recording / reproducing the DVDRAM disc As a result, the program 1b of the core 1 can use the program for the low-speed recording / reproducing apparatus even in the high-speed recording / reproducing apparatus. Because it is easy and less risky, the development period and the number of development personnel can be reduced. In addition, when developing a high-speed recording / reproducing apparatus, the circuit evaluation of the high-speed recording / reproducing apparatus can be performed using the programs 1a and 1b for the low-speed recording / reproducing apparatus, so that the development period and development personnel can be reduced. Even in the high-speed recording / reproducing servo system to which the processing circuit 2 is added, the low-speed recording / reproducing servo system can be realized by operating the program 1a. A low-speed recording / reproducing apparatus with no increase in power is realized by using the same processing circuit as that of the high-speed recording / reproducing apparatus. The attenuation rate of the attenuation filter can be increased to 20 dB or more, and it is possible to effectively eliminate the overlap of the ID area signal on the tracking error signal at the time of DVDRAM high-speed recording / reproduction. Operation modes such as jumping and tracking pull-in, where servo hold processing is impossible In this case, a decrease in servo stability due to ID region signal superimposition can be avoided, and noise due to ID region signal superimposition can be effectively removed. As a result, fluctuations in the track cross signal period during jumping can be suppressed and stable. Speed control is possible, the jump operation can be stabilized and the accuracy can be improved, and the delay time of the track cross signal can be kept small, preventing the delay of the brake pulse timing at the end of the jump and stable tracking pull-in There is an effect that can be realized.

  Furthermore, by setting the period Ts / N to 3 usec or less (sampling frequency of 330 KHz or more), there is an effect that it is easy to configure a high-frequency attenuation filter having an attenuation rate of 8 dB or more and 20 dB or more at 100 KHz and 200 KHz, respectively.

(Embodiment 1)
FIG. 1 shows a block diagram of a first embodiment of the present invention. In FIG. 1, 11 is a head amplifier that converts reflected light from an optical disk into an electrical signal, 12 is an AD converter that converts the head amplifier output into a digital signal, and 13 performs arithmetic processing on the digital signal to generate a tracking error signal. Error signal generating means for generating, 14 a high-frequency attenuation filter for removing high frequency components of the tracking error signal, 15 a servo filter for generating a pickup drive signal from the output signal of the previous high-frequency attenuation filter, and 16 a pickup drive signal A feedback loop is configured by detecting the reflected light that changes as a result of the displacement of the focal position of the reproduction light beam in the radial direction of the disk, and the head amplifier 11.
Further, the processing from the AD converter 12 to the servo filter 15 is performed with a sampling period of 3 usec or less.

  FIG. 2 shows a leaked waveform of the ID area signal to the tracking error signal at the time of DVDRAM reproduction. FIG. 2A is a schematic diagram of the trajectory of the reproduction beam with respect to the data track (LAND / GROOVE) and the ID mark. b) is the output waveform of the error signal generating means 13, (c) is the output waveform of the high-frequency attenuation filter 14, (d) is the output of the servo filter 15, and the waveform shown by the wavy line is the case where the present invention is not used. It is a waveform.

When the ID region signal is superimposed at the timing indicated by α and β, and the light beam is positioned at the approximate center of the track at the timing of α, the ID region signal is vertically moved with respect to the substantially zero level tracking error signal. When the light beam is positioned between the tracks at the timing of β, the ID area signal reaching almost zero level is superimposed on the tracking error signal reaching the maximum amplitude, and the DVDRAM is The frequency of ID region signal superposition when reproduced at 16 × speed is about 220 KHz at the timing of α, and about 110 KHz, which is half that at the timing of β.
Since the high frequency attenuating filter 14 is processed with a sampling period of 3 usec or less, it attenuates the components of the ID region signal superimposing band of 110 KHz to 220 KHz in DVDRAM 16 × playback at 8 dB and 20 dB or more at 100 KHz and 200 KHz, respectively. The waveform of (b) is converted into the waveform of (c), and the output of the servo filter 15 is prevented from being greatly lowered by the superimposition of the ID region signal, and the servo stability is lowered by the superimposition of the ID region signal. It can be avoided.

(Embodiment 2)
FIG. 3 shows a block diagram of the second embodiment of the present invention. In FIG. 3, 31 is a head amplifier, 32 is an error signal generating means, 33 is a low-pass filter, 34 is a binarizing means, 35 is a time axis filter, and 36 is a track cross processing means.

  4 shows a part of the signal waveform in the block diagram shown in FIG. 3, where (a) shows the output signal waveform of the head amplifier 31, (b) shows the output signal waveform of the low-pass filter 33, and (c) ) Is an output signal waveform of the binarizing means 34, and (d) is an output signal waveform of the time axis filter 35, and the ID region signal is superimposed at each timing of α, β, γ, and δ. The operation of the time axis filter 4 is the same as that of the conventional example, but the threshold is set to about ½ of the ID area duration.

  At the timings α and β, even in the conventional example without the low-pass filter 33, the duration of the noise of the track cross signal generated by the superposition of the ID region signal is about ½ of the ID region duration. Even without the low-pass filter 33, it can be removed.

  On the other hand, as described in the first embodiment, the superimposition of the ID region signal generated at the timing of γ when the light beam is positioned between the tracks is changed from the tracking error signal having reached the maximum amplitude to the substantially zero level. Since it is superimposed as a reaching waveform and is in a state where the binarization threshold is slightly exceeded or not exceeded over the duration of the ID region, the level of the superimposed signal is set by passing through the low-pass filter 33. It is possible not to reach the zero level, and in the binarized signal, it is possible to reduce the pulse duration by superimposing the ID region signal to ½ or less of the ID region duration.

  Therefore, even if the threshold value of the time axis filter 35 is set to ½ of the ID region duration, noise due to the superimposition of the ID region signal can be effectively removed. As a result, the fluctuation of the track cross signal period during the jump is suppressed and stable. Enables speed control to stabilize the jump operation and improve accuracy, while keeping the delay time of the track cross signal small to prevent the delay of the brake pulse timing at the end of the jump and stable tracking pull-in Can be realized.

(Embodiment 3)
FIG. 5 shows a block diagram of the third embodiment of the present invention. In FIG. 5, 51 is a processing circuit 1, 52 is a program 1a, 53 is a program 1b, 54 is a processing circuit 2, 55 is a program 2a, and 56 is a program 1c.

The program 1a is a program that performs servo processing with a cycle Ts, and is controlled by a program 1b that performs other control processing. The program 1b further processes commands from a host system (not shown).
The program 1a and the program 1b can realize a servo system having a sampling period Ts on the processing circuit 1, and the servo system of the low speed recording / reproducing apparatus should be realized by a combination of the processing circuit 1, the program 1a, and the program 1b. I can do it.

  In constructing the servo system of the high-speed recording / reproducing apparatus, in order to realize the sampling period of 3 usec or less shown in the first embodiment, the processing circuit 2 operating at the sampling period Ts / N and the program 2a operating on the processing circuit 2 However, the program 2a is configured to perform equivalent processing by replacing the program 1a, and the control from the program 1b is the same as that of the program 1a. There is no need to change from the servo system, and the high-speed recording / reproduction can be performed simply by deleting or stopping the program 1a and adding the program 1c that controls the control interface as necessary to the servo system of the low-speed recording / reproducing apparatus. Servo system can be constructed.

  With the configuration described above, the only program that needs to be newly developed when developing a high-speed recording / reproducing servo system is the program 2a and, if necessary, the program 1c. Therefore, it is possible to reduce the development period and development personnel. It becomes.

  Further, in the development stage of the high-speed recording / reproducing device, the circuit evaluation of the high-speed recording / reproducing device can be performed by operating the programs 1a and 1b, which are programs of the existing low-speed recording / reproducing device. It becomes possible to reduce the development period and development personnel of the double speed recording / reproducing apparatus.

  Even in the high-speed recording / reproducing servo system to which the processing circuit 2 is added, the low-speed recording / reproducing servo system can be realized by operating the program 1a. A low-speed recording / reproducing apparatus with no increase in power can be realized by using the same processing circuit as the high-speed recording / reproducing apparatus.

  The optical disk recording / reproducing apparatus according to the present invention is very effective in that the servo can be stabilized by a simple method, particularly in an optical disk recording / reproducing apparatus which performs high-speed recording / reproducing of DVDRAM up to 16 × speed. .

1 is a block diagram showing a first embodiment of the present invention. Waveform of leaked ID area signal during DVDRAM playback Block diagram of the second embodiment of the present invention Part of signal waveform diagram in block diagram shown in FIG. Block diagram of the third embodiment of the present invention Block diagram of tracking servo section of conventional optical disk recording / reproducing apparatus Operation waveform diagram of conventional optical disc recording / reproducing apparatus Block diagram of track cross signal generator of conventional optical disc recording / reproducing apparatus Operation waveform diagram of track cross generator of conventional optical disc recording / reproducing apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Head amplifier 12 AD converter 13 Error signal production | generation means 14 High-pass attenuation filter 15 Servo filter 16 Pickup 31 Head amplifier 32 The error signal production | generation means 33 is the low-pass filter 34 The binarization means 35 The time axis filter 36 The track cross processing means 51 Processing Circuit 1
52 Program 1a
53 Program 1b
54 Processing Circuit 2
55 Program 2a
56 Program 1c

Claims (8)

  An optical disc recording / reproducing apparatus characterized in that, in a servo program for performing servo processing of an optical disc recording / reproducing apparatus, the servo program has a high-frequency attenuation filter function having an attenuation factor of 8 dB and 20 dB or more at 100 KHz and 200 KHz, respectively. In the servo signal processing circuit of the optical disc recording / reproducing apparatus,
AD conversion means;
Tracking error signal calculating means for calculating a tracking error signal from the conversion result of the AD converter;
A low pass filter,
Binarization means for generating a track cross signal by binarizing the output of the low-pass filter;
A time axis filter means for removing pulses having a width less than a set width from the input track cross signal,
An optical disc recording / reproducing apparatus, wherein the threshold value set in the time axis filter means is set to be 1/2 or more of an ID area duration at a linear velocity for recording / reproducing a DVDRAM disc. A processing circuit 1 capable of operating a program 1a for performing servo processing with a cycle Ts and a program 1b for performing other control processing;
A first memory storing only the program 1b;
A processing circuit 2 in which a program 2a for performing processing equivalent to the program 1a at a cycle Ts / N operates;
An optical disc recording / reproducing apparatus configured by a second memory storing the program 2a. The processing circuit 1 includes an AD converter 1 that samples a plurality of servo signals at a cycle Ts,
The optical disk recording / reproducing apparatus according to claim 3, wherein the processing circuit (2) includes an AD converter (2) that samples a plurality of servo signals at a cycle of Ts / N. A processing circuit 1 capable of operating a program 1a for performing servo processing with a cycle Ts and a program 1b for performing other control processing;
A first memory storing only the program 1b;
A processing circuit 2 in which a program 2a for performing processing equivalent to the program 1a at a cycle Ts / N operates;
A second memory storing the program 2a;
The optical disc recording / reproducing apparatus characterized in that the program 2a has a high-frequency attenuation filter function having attenuation factors of 8 dB and 20 dB or more at 100 KHz and 200 KHz, respectively. A processing circuit 1 capable of operating a program 1a for performing servo processing with a cycle Ts and a program 1b for performing other control processing;
A first memory storing only the program 1b;
A processing circuit 2 in which a program 2a for performing processing equivalent to the program 1a at a cycle Ts / N operates;
A second memory storing the program 2a;
Tracking error signal calculating means for calculating a tracking error signal from the AD conversion result of the reproduction signal input to the processing circuit 2;
A low pass filter,
Binarization means for generating a track cross signal by binarizing the output of the low-pass filter;
A time axis filter means for removing pulses having a width less than a set width from the input track cross signal,
An optical disc recording / reproducing apparatus, wherein the threshold value set in the time axis filter means is set to be 1/2 or more of an ID area duration at a linear velocity for recording / reproducing a DVDRAM disc. A processing circuit 1 capable of operating a program 1a for performing servo processing with a cycle Ts and a program 1b for performing other control processing;
A first memory storing only the program 1b;
A processing circuit 2 in which a program 2a for performing processing equivalent to the program 1a at a cycle Ts / N operates;
A second memory storing the program 2a;
Tracking error signal calculation means for calculating a tracking error signal from the AD conversion result of the reproduction signal input to the processing circuit 2;
A low pass filter,
Binarization means for generating a track cross signal by binarizing the output of the low-pass filter;
A time axis filter means for removing pulses having a width less than a set width from the input track cross signal,
The program 2a has a high-pass attenuation filter function having an attenuation rate of 8 dB and 20 dB or more at 100 KHz and 200 KHz, respectively.
An optical disc recording / reproducing apparatus, wherein the threshold value set in the time axis filter means is set to be 1/2 or more of an ID area duration at a linear velocity for recording / reproducing a DVDRAM disc. 8. The optical disc recording / reproducing apparatus according to claim 3, wherein the cycle Ts / N is 3 usec or less.

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