JPH06111492A - Recording and reproducing method - Google Patents

Abstract

PURPOSE:To stably reproduce data for a defect and sticking of dust in a VFO drawing pattern area. CONSTITUTION:A VFO recording pattern for a prescribed interval is checked by a defect detection circuit 15 at a RAW processing time, and a RAWERR signal is outputted for executing the alternate processing of a sector by a drive controller at an abnormal time. Further, a loop gain in a VFO circuit 9 is lowered in recovery processing in data reproduction, a system is made a narrow band, and the reproduction of the data in a defective part is executed stably. Then, when the defect exists in a VFO synchronizing signal recording area, abnormality is reported to a host device at the RAW processing time, and the alternate processing of the sector is executed, and further, since the VFO circuit is made hard to be affected by disturbance at the time of processing read recovery, the reproduction of the data is executed stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital data recording / reproducing system using a recording medium such as an optical disk, a magnetic disk, a magnetic tape, an optical card, a magnetic card, etc. The present invention relates to a digital data recording / reproducing system capable of preventing defects.

[0002]

2. Description of the Related Art As a conventional technique relating to this kind of digital data recording / reproducing apparatus, for example, Japanese Patent Application Laid-Open No. 1-277.
Techniques described in Japanese Laid-Open Patent Application No. 371, Japanese Patent Laid-Open No. 2-83862, etc. are known.

The prior art will be described below with reference to the drawings by taking a data reproducing method in an optical disk device as an example.

FIG. 5 is a block diagram showing the structure of a digital data reproducing system according to the prior art. In FIG.
5 is a phase comparator, 6 is a loop filter, 7 is an amplifier, 8
Is VCO (Voltage Controlled Oscillator), 10
Is a demodulation circuit, and 12 is a gain switch.

In FIG. 5, the reproduction signal of the digital data read from the optical disk (not shown) is phase-compared with the reproduction clock signal of the VCO 8 by the phase comparator 5. The phase shift amount detected and output by the phase comparator 5 is transmitted to the VCO 8 via the loop filter 6 and the amplifier 7. As a result, the VCO 8 controls the oscillation frequency of the synchronous clock signal with respect to the reproduction signal. The clock signal synchronized with the reproduction signal is given to the decoding circuit 10,
The demodulation circuit 10 generates a data bit from the reproduction signal based on this clock signal and outputs it.

The reproduction signal for controlling the VCO 8 described above is a reproduction signal of a signal recorded in a portion called a VFO pull-in pattern portion arranged at the head of the preformat portion and the data portion in the format of the optical disc described later. Ah.

The circuit including the phase comparator 5, the loop filter 6, the amplifier 7 and the VCO 8 described above is a circuit called a VFO circuit. In this VFO circuit, the phase comparator 5 reproduces a signal from the recording medium and the VCO 8 Output the phase difference of the output signal, and the loop filter 6 outputs the phase-compensated and band-limited VCO control signal to control the VCO 8, and thereby the reproduction signal and the reproduction clock signal which is the output signal of the VCO. The phases are configured to be synchronized.

Further, in the circuit shown, the VCO 8 outputs the center frequency of the self-oscillation frequency when the data is not reproduced, and when the data is reproduced, the VCO 8 pulls in the VFO pull-in pattern, and the gain switching unit 12 The cutoff characteristic of the loop filter 6 is switched to a wide band by the gain switching signal of, the loop gain of the amplifier 7 is set to a high gain state, and the pull-in can be completed within a short time of preamble reproduction. After the pull-in, the cut-off characteristic of the loop filter 6 is narrowed by the loop gain switching signal, and the loop gain of the amplifier 7 is set to a low gain so that the phase lock cannot be lost by a slight disturbance.

Generally, when the above-mentioned VFO pull-in pattern of the recording medium is defective, a normal reproduction clock signal cannot be obtained, and the VFO circuit cannot synchronize the clock signal with the reproduction signal, resulting in a reproduction signal. It becomes impossible to perform normal demodulation of. Therefore, normally, a digital information recording / reproducing apparatus is configured to include a plurality of VFO pull-in patterns of a pre-formatted portion as described in, for example, optical disc technology (issued by Radio Engineering Co., Ltd.) Item 224 to Item 233. Even if some of them are missing due to a defect, the VFO circuit can perform VFO pull-in in the remaining area.

Further, the recording / reproducing apparatus according to the prior art generally has only one VFO pull-in pattern area in the data portion for recording / reproducing by the user, but the data is reproduced immediately after the recording. If it cannot be demodulated correctly, it is judged whether it can be demodulated correctly.
Reed After Write (hereinafter referred to as RAW) processing for re-recording in another sector is being performed. For this reason, in the above-mentioned conventional technique, even if the VFO pull-in pattern portion of the data portion is missing and the VFO circuit cannot perform the VFO pull-in and the data cannot be reproduced, the data becomes the alternative sector. It has been recorded again, so there is no problem. Further, in the above-mentioned conventional technique, in the data reproduction, even if the data cannot be correctly reproduced once, the data is repeatedly reproduced several times (hereinafter referred to as read recovery), and the recorded data can be reproduced as much as possible.

[0011]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
If there is a defect in a part of the VFO pull-in pattern area of the recording medium, or if movable dust adheres to the area of the recording medium, the VFO circuit speeds up the VFO pull-in operation in that area. Since the cutoff characteristic of the filter is broadened and the loop gain is increased, data is reproduced in a state where the VCO control signal is unstable, responding promptly to pulse loss and pulse phase shift.

For this reason, in the above-mentioned conventional technique, during RAW processing, even if the VFO happens to fall normally within a predetermined phase range in the unstable state and the data can be demodulated correctly, it is always necessary to reproduce the data. There is a problem that the VFO pull-in is performed within the predetermined phase range and the data may not be correctly demodulated, and the recorded data may not be normally demodulated, resulting in reproduction failure. is doing.

An object of the present invention is to solve the above-mentioned problems of the prior art and to make it possible to stably reproduce the data even when the VFO pull-in pattern area has a defect or dust is attached. It is to provide a recording and reproducing system.

[0014]

According to the present invention, the above object is to detect a missing pulse in a predetermined period in a VFO pull-in pattern area during RAW processing for a defect of a recording medium,
When this missing pulse is detected, the drive controller is caused to perform sector replacement processing, and in the read recovery operation, the loop gain of the VFO is lowered so as not to respond immediately to the missing pulse and the phase shift pulse. Can be stably reproduced during data reproduction.

That is, the purpose is to check for a pulse loss in the VFO pull-in area of the recording medium for a predetermined period in the RAW reproduction mode, and when a pulse loss is detected, report a recording error (RAW error) to the drive controller. The sector replacement process, and
During read recovery operation from the drive controller,
By narrowing the cutoff characteristics of the loop filter and lowering the loop gain, VFO pulse abnormality (missing,
This is achieved by deteriorating the responsiveness to the phase shift) and enabling stable data reproduction.

[0016]

The present invention has the above-mentioned configuration and has the V part of the data section.
When there is a defect in the FO pull-in area, the defect is detected in the reproduction mode of the RAW process, the recording abnormality is reported to the drive controller, and the sector replacement process is performed. Therefore, when the data is reproduced, the defective sector is reproduced. There is no occurrence of defective reproduction of data.

Also, regarding VFO abnormality (dust etc.) that occurs after RAW, by reducing the VFO gain in the read recovery process and reproducing the data, the responsiveness of the VFO is deteriorated and no response is made to the abnormal signal. Therefore, stable data reproduction can be performed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the recording / reproducing system according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram for explaining the relationship between the disk format and VFO loop gain, and FIG. 3 is a block diagram showing the configuration of a defect detection circuit. FIG. 4 is a timing chart for explaining the operation. 1 and 3, 1 is an optical head,
2 is an amplifier, 3 is a differentiating circuit, 4 is a pulsing circuit, 9 is V
FO circuit, 11 AND gate, 13 drive controller, 14 sector mark detection circuit, 15 defect detection circuit, 15a VFO lead-in position detection circuit, 16, 1
Reference numeral 8 is a counter, 17 and 20 are flip-flops, 19 is a decoder, and other reference numerals are the same as in the case of FIG.

In the embodiment of the present invention shown in FIG. 1, the reproduction signal of the recording information read from the recording medium (not shown) by the optical head 1 passes through the amplifier 2, the differentiating circuit 3 and the pulsing circuit 4. After that, pulse trains of "1" and "0" corresponding to the recorded information are generated. Since the pulse train obtained by this is a signal having jitter due to fluctuations in the rotation of the disk, deviation of the write timing during recording, etc., the VF composed of the phase comparator 5, the loop filter 6, the amplifier 7 and the VCO 8 is used.
The O circuit 9 generates a timing signal (reproduction clock signal) synchronized with the generated pulse train, and the demodulator 10 converts the timing signal (reproduction clock signal) into reproduction information based on this signal.

Next, a timing signal reproducing operation by the VFO circuit 9 will be described with reference to FIG.

An optical disk is usually composed of a large number of sectors for recording data, and each sector is composed of a preformat section and a data section separated by a gap, as shown in FIG. The preformat section includes a sector mark, an ID section VFO pull-in pattern, and a sector address, and the data section includes a data section VFO pull-in pattern and data.

The VFO circuit 9 uses the pulse train in the area of the VFO pull-in pattern of the recording medium shown in FIG.
Performs FO pull-in operation. At this time, the VFO circuit 9
The loop gain switch 12 increases the gain of the amplifier 7 and widens the bandwidth of the loop filter 6 to increase the loop gain.
The FO pull-in operation is completed in a short time.
Further, after the VFO pull-in is completed, the VFO circuit 9 is controlled so that the loop gain becomes low so as to prevent runaway due to a disturbance such as a medium defect.

By the way, if there is a medium defect near the timing of switching the loop gain, the VFO circuit 9 becomes unstable in an attempt to follow the pulse train reproduced from the defect. Therefore, even if the VFO circuit 9 happens to normally perform the VFO pull-in during the execution of the RAW process and the reproduced data can be correctly demodulated, the data cannot be properly demodulated and the reproduction failure occurs. There is.

In order to avoid this, according to one embodiment of the present invention, during the RAW processing, it is judged whether or not the pulse train is normally generated by recognizing the pattern of the pulse train, and if an abnormality is detected by this judgment. , The drive controller is informed of the recording abnormality by the RAW ERR signal and the replacement process is performed. In this pulse train pattern determination, the VFO for detecting the VFO pull-in start position is detected by the mark detection output from the defect detection circuit 15 and the sector mark detection circuit 14.
Pull-in position detection circuit 15a and AND gate 11
Is performed by a circuit configured by

Further, according to one embodiment of the present invention, a mobile VFO abnormality due to dust adhesion or the like (a signal which can be normally reproduced without dust adhered at the time of RAW is a VFO due to dust adherence at the time of data reproduction). In the case of abnormality and data reproduction failure), the drive controller 13 outputs a read recovery signal to lower the loop gain of the VFO circuit 9 via the loop gain switch 12 to a value lower than that during normal data reproduction. , Playing data.

As a result, the embodiment of the present invention does not significantly change the VCO control signal due to the abnormal reproduction pulse due to dust. Therefore, even in such a case, the data bit can be demodulated without causing defective data reproduction. can do.

Next, with reference to FIGS. 3 and 4, the specific structure and operation of the circuit for judging the pattern of the pulse train, which is composed of the defect detection circuit 15, the VFO lead-in position detection circuit 15a and the AND circuit 11, will be described. explain.

The VFO pull-in pattern is recorded as a pattern having a constant pulse interval T, as shown as the reproduction pulse signal 27 in FIG. The counter 16 detects the period T of the reproduction pulse signal by counting the system clock signal, and if the next pulse is not input even when the period T is equal to or longer than the fixed period T, the defect detection signal 25
Is generated and the flip-flop 17 is set. This defect detection signal is latched by the flip-flop 17 until the next sector and reset by the sector mark signal 21 of the next sector.

The counter 18 detects the position detection signal 2 of the VFO pull-in pattern area of the data portion from the sector mark signal.
4 and receives this signal, the decoder 19
The set signal 22 is generated at the beginning of the pull-in pattern area and the reset signal 23 is generated at the end thereof. The flip-flop 20 is controlled to be set or reset by these signals, and its output is given to the flip-flop 17 to control the latch of the defect detection signal 25.

The AND gate 11 confirms that the defect signal is a signal during RAW operation, and outputs the defect signal during RAW operation to the drive controller as a RAW ERR signal 26. Then, the drive controller 13
Checks the RAW ERR signal 26 before processing the next sector, and if there is an abnormality report, performs sector replacement processing.

In the above-described embodiment of the present invention, the means for switching the loop gain during the read recovery operation is
It can be easily configured by a high-speed analog switch, a switching circuit using transistors, and the like.

According to the above-described embodiment of the present invention, with respect to the defect of the recording medium, the lack of the pulse for the predetermined period of the VFO pull-in pattern area is detected during the RAW processing, and when the lack of the pulse is detected, the drive is performed. Since the controller is made to perform the sector replacement process, and in the read recovery operation, the loop gain of the VFO is made low so as not to respond to the pulse loss and the phase shift pulse immediately, the recorded data is stably reproduced at the time of reproducing the data. be able to.

[0034]

As described above, according to the present invention, it is possible to suppress the malfunction of the VFO pull-in due to the defect of the recording medium, the adherence of the moving dust, etc., so that the defective reproduction of the data can be reduced. .

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a disk format and a loop gain of VFO.

FIG. 3 is a block diagram showing a configuration of a defect detection circuit.

FIG. 4 is a timing chart explaining the operation.

FIG. 5 is a block diagram showing a configuration of a conventional technique.

[Explanation of symbols]

 1 Optical Head 2 Magnifier 3 Differentiation Circuit 4 Pulse Circuit 5 Phase Comparator 6 Loop Filter 7 Magnifier 8 VCO 9 VFO Circuit 10 Demodulation Circuit 11 AND Gate 12 Loop Gain Switcher 13 Drive Controller 14 Sector Mark Detection Circuit 15 Defect detection circuit 15a VFO lead-in position detection circuit 16, 18 Counter 17, 20 Flip-flop 19 Decoder

Claims (2)

[Claims] 1. A recording / reproducing system comprising a VFO circuit for generating a bit synchronization signal from a read signal read from a disk, wherein the loop gain of the VFO circuit is lower than that during normal data reproduction, and a cut-off frequency of a loop filter. A recording / reproducing method characterized by narrowing the width to reproduce data during recovery operation. 2. A recording / reproducing system comprising a VFO circuit for generating a bit synchronizing signal from a read signal read from a disk, and a defect detector for detecting a defect of a digital data recording medium, and a position detector for a VFO pull-in area. A recording / reproducing system characterized by comprising a sector replacement process when a medium defect is detected during RAW.