JP2002150564A - Decoder for disk-like recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decoder for a disk-like recording medium for reproducing an information signal recorded in the groove of an optical disk having a land pre-pit without being interfered by its land pre-groove. SOLUTION: Concerning reproducing of the information signal run-length- coded and recorded in the groove 221 of the optical disk 22 where pre-pit information 223 is formed in a land part 222, in the case of detecting the reproducing position of a pre-pit signal by a pre-pit position detection means 32 and decoding a signal obtained by reading the disk 22 by a viterbi decoding signal, the decoder of the disk-like recording medium stops the viterbi decoding of the signal read from the optical disk with the pre-pit signal and decodes the information signal which does not include an error signal occurring as the result of being interfered by the pre-pit signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recording information on a groove of an optical disk by forming auxiliary information such as a block address as land pre-pits on a land in advance, and recording signals recorded on the land pre-pits. The present invention relates to a decoding device that records an information signal on an optical disc based on the information signal and decodes the information signal recorded on a disc-shaped recording medium such as an optical disc for reproducing the recorded signal.

[0002]

2. Description of the Related Art Conventionally, as an example of an optical disk apparatus, when an information signal is recorded in an optical groove, an optical disk in which auxiliary information such as a block address is formed in advance as land prepits in a land is used. While recording information signals based on the pits,
As a method of reproducing the recorded information, there is an optical disk recording device called a DVD-RW and a decoding device.

In the recording and decoding apparatus using the optical disk, there is a concern that the land pre-pits may affect the reproduction performance of the reproduction signal. Japanese Patent Application No. 2000-112246 entitled "Information Signal Recording Method, Reproduction Method and Recording Medium" has been filed.

On the other hand, in a recording medium such as an optical disk which requires a high information recording density, it is possible to prevent the deterioration of the reproduction signal quality that occurs when recording and reproducing and the deterioration of the reproduction signal that occurs due to the increase in intersymbol interference. However, in order to improve the reliability of a reproduced signal, a Viterbi algorithm is often used in a decoder for decoding a recorded reproduced signal.

[0005]

By the way, DVD-R
Recording of an information signal on an optical disc such as W is performed in a groove between lands. And that DV
Land pre-pits are formed in the D-RW in order to manage addresses of information to be recorded.

The reproduction of the information signal recorded based on the information of the land pre-pit is performed while reading the information recorded in the groove. At this time, the signals of the lands on both sides of the groove are also reproduced at the same time. As a result, the reproduced signal from the formed land pre-pit becomes interference distortion.

A method is conceivable in which redundant bits for reducing the interference distortion generated in such a manner are recorded in a groove adjacent to the position where the land pre-bit is recorded. However, even in such a case, since the redundant pits are interfered by the land pre-pits recorded adjacently,
It has been desired to realize a method of recording a signal in a groove adjacent to a land prepit without losing the high-density recording property of the optical disc and reproducing the signal without receiving interference from the land prepit.

That is, the signal recorded on the disk is reproduced by the Viterbi decoding method using the run-length limit of the run-length code. It is necessary to realize an optical disk recording and decoding device that does not reduce the density.

The present invention has been made in view of the foregoing problems, and has been made in view of the problem that reproduction of an information signal recorded in a predetermined format on an optical disk or the like having land pre-pits can be performed by reducing interference between adjacent pre-pits and always improving the information signal. It is an object of the present invention to provide a disk-shaped recording medium decoding device that can reproduce the data in a state.

[0010]

The present invention comprises the following means (1) to (4) to solve the above-mentioned problems. That is,

1) An information signal to be supplied is recorded by a recording device as a run-length encoded signal on a groove of a disc-shaped recording medium in which auxiliary information is formed as pre-pits at predetermined intervals on a land. The recorded encoded signal is read from the disc-shaped recording medium, and the encoded signal obtained by the reading is decoded to obtain the information signal. A pre-pit position extracting means (32) for extracting a signal position of the pre-pit signal from which the pre-pit is reproduced and read from the coded signal, and decoding the read coded signal by a process including a metric operation. Viterbi decoding means for obtaining a decoded signal (33)
And a subsequent signal processing means (34a) for performing signal processing on the decoded signal based on the signal position of the pre-pit signal to obtain the information signal (34a). Decoding device.

2) An encoded signal obtained by run-length encoding an information signal to be supplied to a groove of a disk-shaped recording medium in which auxiliary information is formed as pre-pits at predetermined intervals on a land portion together with a synchronization signal by a recording device. An apparatus for decoding a disc-shaped recording medium which is recorded and reads out the recorded coded signal and synchronization signal from the disc-shaped recording medium, and decodes the coded signal obtained by the reading to obtain the information signal. A synchronous signal extracting means (33) for extracting the synchronous signal from the read encoded signal.
4) a pre-pit position extracting means (335) for extracting a position at which a pre-pit signal is reproduced based on predetermined position information at which the pre-pit is recorded, from the synchronizing signal position extracted by the synchronizing signal extracting means; Viterbi decoding means (331, 332, 3) for decoding the read coded signal by a process including a metric operation to obtain a decoded signal.
33), wherein the Viterbi decoding means is configured to have a function of stopping the metric calculation based on the pre-pit position information obtained by the pre-pit position extracting means. Decoding device.

3) An information signal to be supplied is recorded by a recording device as a run-length encoded signal on a groove of a disc-shaped recording medium in which auxiliary information is formed as pre-pits at predetermined intervals on a land portion. The recorded encoded signal is read from the disc-shaped recording medium, and the encoded signal obtained by the reading is decoded to obtain the information signal. A pre-pit position extracting means (32) for extracting a signal position of the pre-pit signal from which the pre-pit is reproduced and read from the coded signal, and decoding the read coded signal by a process including a metric operation. Viterbi decoding means for obtaining a decoded signal (33)
Wherein the Viterbi decoding means is configured to stop the metric operation on the encoded signal mixed with the pre-pit signal based on the signal position information of the supplied pre-pit signal. Decoding device for a disc-shaped recording medium.

4) An information signal to be supplied is recorded by a recording device as a run-length encoded signal in a groove of a disc-shaped recording medium in which auxiliary information is formed as pre-pits at predetermined intervals on a land. The recorded coded signal is read from the disc-shaped recording medium, and the read coded signal is decoded by the disc-shaped recording medium decoding device which decodes the coded signal to obtain the information signal. A pre-pit position extracting means (32) for extracting a signal position of a pre-pit signal from which the pre-pit is reproduced and read out from the encoded signal; Signal selecting means for selecting either the output coded signal or a predetermined signal value to obtain a selection signal ( 331b) and Viterbi decoding means (33) for decoding the run-length encoded and recorded signal from the selection signal obtained by the signal selection means to obtain a decoded signal. A decoding device for a disc-shaped recording medium.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a preferred embodiment of a disk-shaped recording medium decoding apparatus according to the present invention will be described. The disc-shaped recording medium decoding device is a device for reproducing the optical disc recorded by the disc-shaped recording medium recording device. First, an outline of the disc-shaped recording medium recording device will be described, and then the disc-shaped recording medium recording device will be described. The decoding device will be described.

FIG. 1 shows a schematic configuration of a disk-shaped recording medium recording apparatus for recording on an optical disk on which prepits are formed.
FIG. 2 shows a schematic configuration of a disc-shaped recording medium decoding device having a function of normally reproducing a signal read by receiving the interference of the pre-pits, and the operation of these devices will be outlined.

First, the recording device for a disc-shaped recording medium is a recording unit 1.
The recording unit 1 includes an MPEG-2 encoder 11a, an AC-3 encoder 11b, a mapping circuit 12, a run-length encoding circuit 13, a digital modulation circuit 14, a writing processing circuit 15, and a reading processing circuit 16. , A pre-pit detection circuit 17, and a redundant bit generation circuit 18.

The medium section 2 comprises an optical head 21, a disk-shaped recording medium 22 on which pre-pits are formed, and a spindle motor 23. Further, the disc-shaped recording medium decoding apparatus includes the above-described medium unit 2 and the reproducing unit 3, and the reproducing unit 3 includes a read processing circuit 31a, a reproduction equalizing circuit 31
b, prepit detection circuit 32, Viterbi decoding circuit 33, digital demodulation circuit 34, demapping circuit 35, MPEG
-2 decoder 36a and AC-3 decoder 36b.

In the disk-shaped recording medium recording apparatus thus configured, the video signal is transmitted to the MPEG-2 encoder 11.
According to a, the audio signal accompanying the video signal is encoded by the AC-3 encoder 11b, and the encoding of the video signal is performed, for example, by MPEG (moving picture experts group) -2.
According to the standard, the audio signal is encoded according to the AC-3 standard.

These encoded video and audio signals and the redundant bits generated by a redundant bit generation circuit 18 described later are supplied to a mapping circuit 12 and are generated as a bit stream signal which is a serial signal. The generated signal is supplied to the run-length encoding circuit 13.

In the run-length encoding circuit 13, the supplied bit stream signal is converted into a digital signal divided by a predetermined number of bits, and the separated signals are sequentially followed by a predetermined number of "0". The signal is converted to a run-length code in which “1” exists, and the signal thus converted is supplied to the digital modulator 14.

The digital modulator 14 generates a signal obtained by subjecting the supplied signal to NRZI (Non Return to Zero Inverse) conversion, and the converted signal is supplied to a write processing circuit 15, which outputs a laser (not shown). The signal is converted into a signal for driving the diode to emit light and supplied to the optical head 21.

The optical head 21 of the recording unit 2 generates a signal obtained by modulating a laser beam in accordance with the supplied signal, and the signal is applied to the disk-shaped recording medium 22 for recording. The signal recorded on the disk by the reading function and the pre-pit position information previously formed and recorded on the disk-shaped recording medium 22 are both read to obtain a reading signal.

A read signal obtained by the optical head 21 is supplied to a read processing circuit 16 to obtain a signal recorded on a disk-shaped recording medium and pre-pit information. A signal containing the obtained pre-pit information is a pre-pit signal. The pre-pit position signal is supplied to the detector 17 where the pre-pit position signal is detected. The pre-pit position is supplied to the redundant bit generation circuit 18 described above.

In the redundant bit generation circuit 18, prebit position information is generated based on the prebit information of the disk-shaped recording medium detected by the prebit detection circuit 17, and redundant bits are generated based on the generated prebit position information. The generated redundant bits are supplied to the above-described mapping circuit 12 so that the redundant bits are inserted into the bit stream. Then, the redundant bits can be inserted by the run-length encoding circuit 13.

Next, the operation of the disc-shaped recording medium decoding apparatus for reproducing the disc-shaped recording medium thus recorded will be described. First, the optical head 21 of the recording unit reads out a signal recorded on the disk-shaped recording medium 22 rotated by the spindle motor 23 and reads out the signal from the read processing circuit 3 of the reproducing unit 3.
1 is supplied.

In the read processing circuit 31a, the weak signal read by the optical head 21 is amplified, and the frequency characteristics and phase characteristics of the read signal are corrected. A part is supplied to a pre-pit detection circuit 32 to detect a pre-pit position to generate a pre-pit position signal, and another part is supplied to a reproduction equalization circuit 31b to perform reproduction according to a predetermined partial response characteristic. The reproduced and equalized signal is supplied to a Viterbi decoding circuit 33.

In the Viterbi decoding circuit 33, the supplied signal is Viterbi-decoded while referring to the pre-bit position signal supplied from the pre-bit detection circuit 32, and the Viterbi-decoded signal is supplied to a digital demodulation circuit 34. .

The digital demodulation circuit 34 demodulates the run-length signal based on the run-length modulation method performed by the run-length encoding circuit 13, and supplies the demodulated signal to the demapping circuit 35.

In the demapping circuit 35, a bit stream signal obtained as a time-division multiplexed signal is divided into a video signal, an audio signal, and an auxiliary signal (not shown), and the video signal is supplied to an MPEG-2 decoder 36a. The video signal is obtained by decoding, and the audio signal is supplied to the AC-3 decoder 36b to be decoded.
An acoustic signal is obtained.

As described above, the video and audio signals supplied to the recording unit 1 are recorded on the disk-shaped recording medium 22 of the medium unit 2, and the recorded signals are read out by the medium unit 2 and read out. The read signal has its readout characteristic corrected, and the above-mentioned partial response characteristic (PR) is given.
The signal to which the PR characteristic is added is supplied to the Viterbi decoding circuit 33. In the Viterbi decoding circuit, the video signal and the audio signal are output as a reproduction signal by the reproduction unit 3 so that the supplied signal is decoded. It has been made.

Next, a disc-shaped recording medium 2 on which a signal is recorded
2 will be described. FIG. 3 shows a top view as seen from the recording surface of the disk-shaped recording medium 22. In the same figure, a groove (groove) is formed on a plane having an upper part in the disk outer circumferential direction and a lower part in the disk inner circumferential direction, and a land is formed between the groove and an adjacent groove.

That is, the meandering portion indicated by the oblique line is a groove, and the groove 221a and the groove 22
Both are formed like a land 222a between 1b, and the land 222a has a part called a pit, and the part is a land pre-pit 223a.

The disk-shaped recording medium 22 thus formed
Detects a land pre-pit, and an information signal is recorded in an adjacent groove immediately after the land pre-pit.

In recording the information signal, the detection of the pre-pit position in the recording section 3 is performed by the pre-pit detection circuit 17.
In the mapping circuit 12, packetized video and audio signals are supplied to the run-length encoding circuit 13 following the position of the pre-pit.

The encoded video and audio signals recorded following the land pre-pits are read by the medium unit 2 and the read signals are read by the reproducing unit 3.
And a reproduction signal is obtained.

At this time, reading of the signal recorded in the groove is performed by the optical head 21.
The narrowing of the laser beam spot for reading out the signal recorded in the groove performed by 1 is performed by an optical system including a lens system (not shown), but the narrowed beam spot is actually larger than the groove width. Since the light is also applied to the land, the signal of the land pre-pit recorded on the land is also reproduced at the same time.

In order to reduce the influence of the land pre-pit signal thus generated on the reproduction signal, the reproduction unit 3 performs the position of the land pre-pit to be reproduced by the pre-pit detection circuit 32 and detects the position. By supplying the prepit position signal to the Viterbi decoder 33, the Viterbi decoder 33 is prevented from being interfered by the mixed land prepit signal and decoding an error signal.

Next, a method of preventing the read signal from being disturbed by the land pre-pit signal and the interference distortion caused by the disturbance will be described. FIG. 4 schematically shows the effect of the land prepit on the reproduction of the information signal, which will be described in detail with reference to FIG.

In the figure, (1) shows the position of the detected adjacent pre-pit, (2) shows the position of the recording information mapped by the mapping circuit 12 based on the position of the pre-pit, and (3) Indicates recording data recorded on the disk, and (4) indicates a waveform of a signal obtained by reproducing the data recorded on the disk.

That is, (1) is detected by the pre-pit detector 17, and based on the detected signal, the signal indicating the pre-pit position is designated as the level of "1" for the period of the 2-bit clock. The period of the two-bit clock before this and the five-bit clock including the one-bit clock after the signal are specified by the mapping circuit 12 as the redundant pre-bit period.

In the redundant pre-bit period, the signal level "0" is recorded. Therefore, in this example, the preceding information bit is, for example, "1", the redundant bit period is "0", and The information bits following the redundant bits correspond to a case where a recording signal that is set to, for example, “0” is supplied and recorded.

The signal recorded in this manner is read out by the optical head 21, and the read-out signal is corrected for the readout characteristics and the like of the optical head by the read-out processing circuit 31a, and the corrected signal is reproduced and equalized. The signal is supplied to the circuit 31b.

The reproduction equalization circuit 31b performs reproduction equalization for decoding the signal, which has been run-length encoded by the run-length encoding circuit 13 and modulated by the digital modulation circuit 14, by the Viterbi decoding circuit 33. And a circuit for providing a partial response for that purpose.

Next, the operation in which the run-length coded and digitally modulated signal is reproduced and equalized and Viterbi decoded will be further described. That is, a signal that is converted into a run-length limited code (RLL) performed by the run-length encoding circuit 13 and the modulation circuit 14 and modulated is d = 2, k =
This is an example in a case where RLL (2, 10) having a limit of 10 is used.

In the run-length encoding represented as RL (2, 10), the modulated signal is modulated into a signal having an inversion interval of 3 clocks to 11 clocks (3T to 11T) and recorded on a disk. When reproducing the recorded signal, the partial response characteristic is equalized by the reproduction equalization circuit 31a, and is supplied to the Viterbi decoding circuit 33.

The partial response characteristic (PR) of the reproduction / equalization circuit 31a is obtained by adding a removable intersymbol interference to a transmitted signal and supplying it to a decoder, which transmits the signal while removing it. This is for decoding the information signal.

In the case of a general optical disk transmission system, the partial response to integer values a and b is PR (a,
b, b, a) are used. For example, PR (1,1,1,1) and PR (1,2,2) are used.
Properties such as 2,1) and PR (3,4,4,3) are also used.

Here, for example, PR (1,1,1,1)
A description will be given of the case of using the characteristic of FIG. (4) in FIG. 4 shows a signal waveform when a signal based on the characteristic is supplied to the Viterbi decoding circuit 33. The signal waveform when there is no prepit in an adjacent land is represented by a solid line, and the bit position is indicated by a solid line. The sample value at (data point) is indicated by ● (black circle), an example of a signal waveform when a pre-pit exists in an adjacent land is indicated by a wavy line, and similarly, the sample point at a bit position is indicated by ○ (white circle). .

As described above, when the pre-pit exists in the adjacent land, the reproduction signal is modulated by the effect of the pre-pit, and the modulation is performed beyond the pre-pit position. Despite being redundant bits, the interference propagates to the position of the information signal.

The land pre-pit signal reproduced in this manner is an interference signal generated when the beam of the laser beam of the optical pickup cannot be fully stopped, and exceeds the recording position of the redundant bit. Since the range extends to the area, the bit error rate of the reproduced signal increases as a result.

Here, an increase in the bit error rate of the reproduced signal generated as described above will be described, and then, a method of preventing the increase in the bit error rate will be described. First, PR
When the signal digitally modulated by (1,1,1,1) is supplied to the Viterbi decoder and decoded, the influence of the interference given from the pre-pits 223 extends to the succeeding information bits. The state will be described.

FIG. 5 shows a state transition diagram of a Viterbi decoder used for decoding a signal modulated by PR (1, 1, 1, 1). In the figure, S0 to S5 indicate the states of the signals decoded by the Viterbi decoder, arrows indicate transitions between the states, and the numbers indicated by fractions next to the arrows indicate that the numerator is the Viterbi decoding circuit 33. , And the denominator is the peak value of the signal supplied to the reproduction equalization circuit 31a.

That is, the run length limited code RLL
In the signal modulated by (2, 10), the interval at which the recorded or reproduced data represented by the bit sequence is inverted is 3 to 11 times the bit interval, that is, from 3T to 11T (T
Is limited to a bit interval).

Therefore, when the data to be reproduced changes from 0 to 1 or from 1 to 0, the same data is reproduced continuously 2 to 10 times. The figure shows the state in which the supplied signal is decoded in this way, where the most recent three bits of the decoded signal and the least significant bit (the rightmost digit) are shown. Decoded bits.

At this time, the relationship between the 3-bit value and the state S is as follows: S0 is 000, S3 is 001, and similarly, S4, S5,
011, 111, 110, 100 for S2 and S1
Is decoded. That is, in the state of 000 in S0, if the input signal to the Viterbi decoder is the same 0, 000 is updated, and the next time different data 1 comes in, 000 becomes 001 and the state is S3. .

Since the signal supplied to the Viterbi decoder is a signal coded by RLL (2, 10), the value of 1 is supplied at least twice thereafter, and the decoded result is S4 011 and S5 become 111.

When 1 is continuously supplied in S5, the state remains unchanged at 111 in S5, and when 0 is supplied next time, it becomes 110 in S2, and in this case, 0 is supplied in the next two times.
, The operation of the decoder is continued so that the state of the decoder becomes 100 of S1 and 000 of S0.

In this way, the signal supplied to the Viterbi decoder 33 is decoded, and its transition state can be indicated as a trellis state. FIG. 6 shows the operation of the Viterbi decoding circuit 33 by a trellis diagram.

In the figure, the above-mentioned fractional value (the numerator is the Viterbi decoding circuit 33)
, And the denominator indicates the peak value of the signal supplied to the reproduction equalization circuit 31a).
The same operation as in FIG. 5 is performed.

FIG. 7 shows a metric operation circuit that performs such an operation. In the figure, the target value shown on the left side is the peak value of the signal in an ideal state, and the input data is the reproduction equalization circuit 31 shown as the denominator of the above-mentioned fractional value.
a, the peak value of the signal supplied to a, and L _{0 (k−1)}
L5 _(k-1) is a data value one sample clock before obtained by the metric operation, and L0 _{(k) to} L5 _(k) are newly obtained data values.

Thus, the selection signal 0 and the selection signal 1 are obtained, and the obtained selection signal 0 and the selection signal 1 are obtained.
Are supplied to the path memory circuit. FIG. 8 shows a configuration of the path memory circuit.

The path memory circuit operates on the basis of the supplied selection signal 0 and selection signal 1, and obtains a decoded data sequence by predicting the operation result by the majority decision circuit with the decoded data having the highest probability of occurrence. It is a circuit configured by:

As described above, Viterbi decoding is performed by the metric operation circuit and the path memory circuit. FIG.
2 shows a configuration of a Viterbi decoding circuit according to a second embodiment for performing the Viterbi decoding.

In the figure, the Viterbi decoder 33a of the second embodiment comprises a metric operation circuit 331, a path memory 332, a redundant bit extracting circuit 333, a synchronization detecting circuit 334, and a redundant bit position counter 335. The Viterbi decoder 33a includes a subsequent signal processing circuit 34
a is connected.

Next, the Viterbi decoder 3 configured as described above
3a and the operation of the subsequent signal processing circuit 34a will be described. First, a signal read from the disc-shaped recording medium 22 by the optical head 21, read processing is performed by the read processing circuit 31, and the signal subjected to reproduction equalization processing by the reproduction equalization circuit 31a is subjected to metric calculation as input data y _(k). The signal is supplied to the circuit 331.

In the metric operation circuit 331, a branch metric and a path metric of the supplied signal are calculated for each bit clock based on the control signal supplied from the redundant bit position counter circuit, and the calculation obtained by the calculation is performed. The resulting selection signal is supplied to the path memory 332.

In the path memory 332, the surviving path for the input data y _(k) is determined based on the supplied selection signal, and the determined surviving path information is temporarily stored in the memory circuit, and the surviving path is determined. The information is supplied to the redundant bit extracting circuit 333.

The survivor path information signal supplied to the redundant bit extracting circuit 333 is a binary decoded bit sequence signal, and the signal is a redundant bit extracting circuit 333.
To extract the redundant bit, and the signal from which the information bit is extracted is supplied to the synchronization detecting circuit 334.

In the synchronization detection circuit 334, a synchronization signal (synchronization pattern) is detected from the decoded bit sequence signal from which the information bits are extracted, and a word clock signal synchronized with word data is generated based on the detected synchronization signal. Generated
The word clock signal is supplied to the subsequent signal processing circuit 34a, and the detected synchronization signal is supplied to the redundant bit position counter circuit 335 as a count start signal.

In the redundant bit position counter 335,
The above-mentioned control signal for performing the metric operation based on the supplied count start signal is generated and supplied to the metric operation circuit 331, and a predetermined number of bits are counted from the count start signal to extract the redundant bits. A position signal is generated, and the generated signal is supplied to the redundant bit extracting circuit 333.

In this way, the Viterbi decoding circuit 33a decodes the supplied input data, and decodes the decoded bit sequence obtained from the redundant bit extracting circuit 333.
The word clock obtained from the synchronization detection circuit 334 is supplied to the subsequent signal processing circuit 34a.

The subsequent signal processing circuit 34a obtains decoded information based on the supplied decoded data sequence signal and word clock signal, and performs data demodulation, error correction, and descrambling of the obtained decoded information. For example, a signal processing for compensating the processing performed in the recording unit is performed to obtain a reproduction information signal, and the obtained reproduction information signal is supplied as an output signal.

The operation of the second embodiment by the Viterbi decoding circuit 33a and the subsequent signal processing circuit 34a has been described above. The operation of the decoding circuit for preventing interference from the land prepit signal will be further described. FIG. 10 is a timing chart showing the operation of the decoding circuit for preventing the interference of the signal reproduced from the land prepit.

The signals shown in the figure are a recording signal recorded on a disk-shaped recording medium, a synchronous block signal (11), a land prepit position signal (12), and a count start position signal (13) of a redundant bit counter. , A redundant bit position signal (14) indicating the detected redundant bit position, and a control signal (1) for preventing interference from land pre-pits.
5), and these signals will be sequentially described.

First, the recording synchronization block signal (11) comprises a synchronization pattern bit, an information bit, a redundant bit, and the like. The redundant bit is a signal at the same time as the land prepit position (12). ing.

The land prepits recorded on the disk-shaped recording medium are detected by the prepit detection circuit 17, and the signals mapped by the mapping circuit 12 based on the prepit information generated by the redundant bit generation circuit 18 are output. By being generated.

In the Viterbi decoding circuit 33a, a synchronization pattern recorded in a predetermined bit pattern from the supplied input signal is detected by the synchronization detection circuit 334. At the last position of the detected synchronization pattern, the synchronization detection circuit 334 detects the synchronization pattern. A count start signal (13) is generated.

The redundant bit position counter 335 starts counting by the count start signal,
When a predetermined count number M1 is counted, a redundant bit position signal indicating the first redundant bit position is generated, further counting is started, and when a second predetermined count number M2 is counted, 2 A redundant bit position signal indicating a redundant bit position is generated, and the generated signal is output as a redundant bit position signal (14).

The redundant bit position signal generated in this manner is supplied to a redundant bit extracting circuit 333. The redundant bit extracting circuit 333 generates a redundant bit signal based on the supplied redundant bit position signal (14). A predetermined portion is extracted from the recording synchronization block signal.

A signal for performing the extracting operation is a control signal (15). The control signal is delayed by Tm, which is a delay time based on the memory length of the path memory circuit 332, with respect to the redundant bit position signal. Then, a holding section signal is generated, and the generated holding section signal is supplied to the metric calculation circuit 331 as a control signal.

The circuit operation performed in this manner has been described by exemplifying three land pre-pits and two margin bits in a synchronous block. The position and the number of land pre-pits are further different. The same operation is performed even in the case of a large number, and the interference signal removing method shown here can be applied more widely.

The bit clock signal supplied to the Viterbi decoder 33a is a signal for a bit synchronization clock (bit clock) generated by a PLL circuit (not shown). This is a synchronization signal serving as a reference for circuit operation.

The Viterbi decoding circuit thus configured and its operation are the same as those generally performed, and a detailed description thereof will not be given here.

Next, prevention of interference of land pre-pit signals in the Viterbi decoding circuit 33a performed in this manner will be described. The control of the interference prevention is performed by controlling the metric operation circuit 331 by the control signal supplied from the redundant bit counter 335.

The holding section signal in the control signal indicates the previous value holding section until the start of the metric calculation in the metric calculation circuit 331, and the operation of the metric calculation is controlled by such a control signal.

FIG. 11 shows an input section of the metric operation circuit 331. Referring to FIG.
1a, a selector 331b, and a squaring circuit 331c.

The input section of the metric operation circuit 331 shown here is different from the metric operation circuit in FIG. 7 in that a selector 331b is provided and has a signal switching function. .

The selector 331b includes an adder 331
a and a signal whose level is "0" are supplied as input signals, and one of the two supplied signals is switched based on a control signal and is obtained by being switched. The signal is supplied to the squaring circuit 331c.

That is, when the control signal supplied to the selector 331b is at the high level (1), the signal supplied from the adder 331a is supplied to the squaring circuit 331c, and when the control signal is at the low level (0), The signal of "0" is the squared circuit 331.
c.

Therefore, when the control signal is at a low level, the metric calculation is not updated irrespective of the input signal at the land pre-pit position, and the land pre-pit signal is affected by input data supplied by interference. Thus, Viterbi decoding is performed.

Next, a signal obtained by performing the Viterbi decoding by the metric operation circuit having the selector 331a in the input section will be described. FIG. 12 shows signals when a metric operation is performed by the Viterbi decoder.

In the figure, a control signal (21) supplied to a selector 331a, input data (22) supplied to a metric operation circuit, a code error signal decoded when the selector 331a is not used, and its The signal is represented by an NRZI sequence number (23), and a normally decoded signal that is normally decoded when the selector 331a is used, and the NRZI
This is indicated by (24), which is represented by a series number.

The signal waveforms shown here have the same time relationship as those corresponding to FIG. 4 described above. For example, the time position of the redundant bits shown at the top of the figure corresponds to the redundant bit position (2) shown in FIG. are doing.

The control signal is generated as shown in (21), and a metric calculation suspension section is set based on the control signal. During this period, the selector 331b selects the signal of level "0" and It is supplied to the squaring circuit 331c.

In this way, the metric operation circuit 33
In the input data supplied to No. 1, signals from grooves not adjacent to land prepits are indicated by solid lines and black circles, that is, S signals.
k, Sk + 1, Sk + 2,..., Sk + 7.

[0097] The signal of the portion that has been interfered by the land pre-pit is indicated by a dotted line and a white circle, and the sample values of the signal are indicated by Rk + 3, Rk + 4, Rk + 5, and Rk + 6.

Therefore, when the metric calculation is not stopped by using the control signal (21) based on the land pre-pits, Viterbi decoding with a signal waveform represented as Rk + n (where n is an integer of 3 to 6) is performed. Therefore, the Viterbi decoder decodes assuming that high-level data is input at the time point of k + 4, and decodes and outputs a data sequence (23) of a decoding error.

On the other hand, when the metric calculation stop section is set by the control signal (21) and Viterbi decoding is performed, the calculation operation of the metric calculator is stopped in the calculation stop section and supplied to the Viterbi decoder. Since the signal holds the immediately preceding data value, the Viterbi decoder outputs the normal decoded sequence signal (24).

As described in detail above, for example, the reproduction of the redundant bit signal recorded in the groove adjacent to the land pre-pit is performed by specifying the portion where the land pre-pit signal is reproduced from the signal obtained from the disk. When the redundant bit signal is reproduced together with the land pre-pit signal, a metric operation stop section is set to set a redundant bit signal which is not interfered with by the land pre-pit signal, and an information signal recorded subsequently to the redundant bit signal. Since it can be reproduced, there is no need to provide a protection period for preventing interference with a recordable optical disk having land pre-pits, and recording of an optical disk with high recording efficiency,
A decoding device can be configured.

The circuit operation for removing the interference signal related to the land pre-pit signal of the Viterbi decoding circuit 33a is modulated by the run-length limited code RLL.
Although the case of (2, 10) has been described, the code parameters of the run-length limited code are not limited to this, and for example, when other parameters such as RLL (2, 7) and RLL (1, 7) are used. Performs the same operation.

As for the partial response characteristics, the configuration and operation of the optical disk decoding device for PR (1, 1, 1, 1) have been described in detail, but the partial response characteristics whose characteristics are defined by other parameters are employed. In this case, the same operation is performed.

That is, PR by any parameter
Even in the case of the characteristic, the reproduction equalization based on the characteristic of the PR is performed, and the Viterbi decoder performs a metric operation on the signal subjected to the reproduction equalization, that is, a decoding operation based on a difference between an output sample and a target value. The code value is obtained by calculating the metric value based on the product sum of the difference between the sample value supplied to the Viterbi decoder in the past and the target value.

The reproduction of a signal recorded on a disk with a PR characteristic of, for example, data of 4 clock signals or more is performed due to the interference of a land prepit signal provided on the optical disk. As shown in the figure, if a signal that is significantly different from a signal at a level different from the original target value is supplied, it affects decoding of subsequent bits.

A signal recorded in a groove adjacent to a land on which the land pre-pit signal is recorded has a redundant bit even when redundant bits are inserted to reduce such interference. When decoding the signal following the bit, interference with the subsequent information bit is caused by the error propagation characteristic of the decoding circuit.

Further, in order to prevent interference with subsequent information bits, a selector is provided at the input of the Viterbi decoding circuit to detect an interference signal based on land prepits and to force the signal supplied by the selector. The method of setting the “0” level has been described.

This is based on the fact that the land pre-pit signal is formed in a shape depressed with respect to the land, so that the polarity of the land pre-pit signal is specified. The cancellation may be performed by adding a signal having a polarity opposite to that of the specified signal to the supplied signal to cancel the cancellation.

In order to prevent the interference from the land pre-pit signal, the interference signal caused by the land pre-pit signal has a predetermined signal waveform. May be generated based on the signal waveform when the presence of the signal is detected, and supplied to the Viterbi decoder.

Furthermore, since the generation of an error signal at the time of Viterbi decoding caused by the interference of the land pre-pit signal is limited to the land pre-pit signal period and a signal section immediately thereafter, the error signal is temporarily For example, the error cannot be corrected by the error correction circuit of the subsequent signal processing circuit 34a,
When a correction leakage signal occurs, there is a method in which the error signal portion is corrected to a corrected signal and used.

That is, the error detection of a signal decoded by a Viterbi decoder or the like is performed as a signal of a predetermined block size, so that even if there is one bit missing in the block, it is detected as an error block. Then, it operates to invalidate the signal of the entire block.

If the signal of the block is, for example, data relating to the pixel itself of the coded digital video signal, and if a video error due to a bit error is a data error that is not visually noticeable, about 1 bit It is not preferable to invalidate a large number of bit signals of the entire block as being erroneous for the error signal of

As described above, when it is known that the block in which the error signal has occurred is a signal recorded in the groove adjacent to the land prepit, the signal block is not affected by the breakdown of the information. When it is determined that the influence is small, it is desirable to use a method of using the signal of the data block without invalidating the signal.

Such a determination is possible if the signal reproduced under the influence of the land pre-pits can be specified, and the detection of the land pre-pits in the optical disk decoding device has an important meaning. .

As described above, a disc-shaped recording medium such as a DVD-RW optical disc has been described as an example of a medium on which land pre-pits are recorded.
Even in a high-density recording disk in which an address signal or the like is prerecorded as a pre-information signal as an auxiliary signal for recording at a location adjacent to a recording track, if the recording signal is reproduced by interference from the pre-information signal Identify the portion of the pre-information signal to be reproduced to remove or cancel the interference distortion component generated based on the pre-information signal, or perform a similar operation such as processing an error signal generated by the pre-information signal. And a decoding device for a disk-shaped recording medium for performing the above-mentioned operations.

[0115]

According to the first aspect of the present invention, an information signal supplied based on the pre-pit signal is formatted in a predetermined format on a disk-shaped recording medium in which an address signal or the like is recorded as a pre-pit signal in advance. Generated and recorded as a recorded signal, and the reproduction of the recorded signal reads the signal in the recorded predetermined format, and identifies the reproduced portion where the pre-pit signal interferes with the read signal, Even if the decoded information signal contains an erroneous decoded signal such as an error signal with respect to the identified reproduction portion, the location of the erroneous portion can be specified. , A disc-shaped recording medium decoding that can be supplied as an information signal output adaptively processed according to the content of the corresponding information signal There is an effect that can be configured location.

According to the second aspect of the present invention, an information signal supplied based on the pre-pit signal is synchronized in a predetermined format to a disc-shaped recording medium in which an address signal or the like is recorded as a pre-pit signal in advance. A signal is generated and recorded as a recording signal formatted together with the signal, and the recorded signal is reproduced by reading out the signal in a predetermined format and reproducing it after a predetermined time with respect to the read out synchronization signal. The reproduced portion of the pre-pit signal is specified, and for the specified reproduced portion, the Viterbi decoding of the read signal is performed while the metric operation is stopped, and the error signal is not included in the information signal recorded following the redundant bit. There is an effect that a disc-shaped recording medium decoding device that can obtain an information signal can be configured.

According to the third aspect of the present invention, an information signal supplied based on the pre-pit signal is formatted in a predetermined format on a disk-shaped recording medium in which an address signal or the like is recorded as a pre-pit signal. Generated and recorded as a recorded signal, and the reproduction of the recorded signal is performed by reading the recorded signal in a predetermined format, and specifying a reproduction portion of a pre-pit signal reproduced with respect to the read signal. The supplied information of the reproducing unit is supplied to the Viterbi decoder by a control signal, and the Viterbi decoder performs Viterbi decoding of the supplied signal read out based on the control signal, and is generated by interfering with the land pre-pit signal. There is an effect that a disc-shaped recording medium decoding device capable of obtaining an information signal containing no error signal can be configured.

According to the fourth aspect of the present invention, an information signal supplied based on the pre-pit signal is formatted in a predetermined format on a disk-shaped recording medium in which an address signal or the like is recorded as a pre-pit signal. The recorded signal is generated and recorded, and the recorded signal is reproduced by reading the recorded signal in a predetermined format and reproducing a pre-pit signal reproduced at a predetermined time interval with respect to the read signal. By selecting the read coded signal to a signal having a predetermined signal value by the signal selecting means for the specified reproduced portion, and performing Viterbi decoding on the switched signal. A disc-shaped recording medium capable of obtaining an information signal free of an error signal generated by interference with a land pre-pit signal. There is an effect that it is possible to configure the device.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a disk-shaped recording medium recording apparatus for performing recording on an optical disk on which prepits are formed according to an embodiment of the disk-shaped recording medium recording apparatus of the present invention.

FIG. 2 is a schematic block diagram of a disc-shaped recording medium decoding device having a function of normally reproducing a signal read out due to pre-pit interference according to an embodiment of the present invention.

FIG. 3 is a top view of a recording surface of a disk-shaped recording medium according to an embodiment of the present invention.

FIG. 4 is a diagram schematically showing the effect of land prepits on the reproduction of an information signal in the disc-shaped recording medium decoding device according to the embodiment of the present invention.

FIG. 5 is a diagram showing a state transition of a Viterbi decoding circuit in the disc-shaped recording medium decoding device according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating the operation of a Viterbi decoding circuit in a disc-shaped recording medium decoding device according to an embodiment of the present invention by a trellis diagram.

FIG. 7 is a diagram illustrating a configuration of a metric operation circuit that performs an operation of a Viterbi decoding circuit in the disc-shaped recording medium decoding device according to the embodiment of the present invention.

FIG. 8 is a diagram illustrating a configuration of a path memory circuit that performs an operation of a Viterbi decoding circuit in the disc-shaped recording medium decoding device according to the embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a Viterbi decoding circuit in a second embodiment of the disc-shaped recording medium decoding apparatus according to the embodiment of the present invention.

FIG. 10 is a timing chart showing an operation of a decoding circuit for preventing interference of a signal reproduced from a land prepit according to the embodiment of the present invention.

FIG. 11 is a diagram showing an input unit of a metric operation circuit of a Viterbi decoding circuit in a second embodiment of the disc-shaped recording medium decoding apparatus according to the embodiment of the present invention.

FIG. 12 is a diagram illustrating signals when a metric operation is performed by the Viterbi decoder according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording part 2 Medium part 3 Reproduction part 11a MPEG-2 encoder 11b AC-3 encoder 12 Mapping circuit 13 Run-length encoding circuit 14 Digital modulation circuit 15 Write processing circuit 16 Read processing circuit 17 Prepit detection circuit 18 Redundant bit generation circuit 21 Optical head 22 Disc-shaped recording medium 23 Spindle motor 31a Read processing circuit 31b Reproduction equalization circuit 32 Prepit detection circuit 33 Viterbi decoding circuit 33a Viterbi decoder of the second embodiment 34 Digital demodulation circuit 34a Subsequent signal processing circuit 35 Demapping circuit 36a MPEG-2 decoder 36b AC-3 decoder 221a, 221b, 221c Groove 222a, 222b Land 223a, 223b, 223c Land pre-pit 331 Metric operation circuit 331 a Adder 331b Selector 331c Square circuit 332 Path memory 333 Redundant bit extraction circuit 334 Synchronous detection circuit 335 Redundant bit position counter

Claims (4)

[Claims] An information signal to be supplied is recorded by a recording apparatus as a run-length encoded signal on a groove of a disc-shaped recording medium in which auxiliary information is formed as pre-pits at predetermined intervals on a land. A disc-shaped recording medium decoding device configured to read the recorded coded signal from the disc-shaped recording medium and decode the coded signal obtained by the reading to obtain the information signal. A pre-pit position extracting means for extracting a signal position of a pre-pit signal from which the pre-pit is reproduced and read from the coded signal, and decoding the read coded signal by a process including a metric operation to obtain a decoded signal. Obtaining Viterbi decoding means, and performing signal processing on the decoded signal based on the signal position of the pre-pit signal to obtain the information signal as the information signal Decoding device of the disc-like recording medium, characterized by being configured provided with the subsequent signal processing means fit, a. 2. An information signal to be supplied to a groove of a disk-shaped recording medium in which auxiliary information is formed as pre-pits at predetermined intervals on land portions is encoded by a recording device together with a synchronization signal together with a run-length encoded information signal. A decoding device for a disc-shaped recording medium which is recorded and reads out the recorded coded signal and synchronization signal from the disc-shaped recording medium, and decodes the coded signal obtained by the reading to obtain the information signal. A synchronizing signal extracting means for extracting the synchronizing signal from the read encoded signal; and a synchronizing signal position extracted by the synchronizing signal extracting means, based on predetermined position information at which the pre-pit is recorded. A pre-pit position extracting means for extracting a position at which the pre-pit signal is reproduced, and a process including a metric operation for the read coded signal. And Viterbi decoding means for decoding to obtain a decoded signal, wherein the Viterbi decoding means has a function of stopping the metric calculation based on the pre-pit position information obtained from the pre-pit position extracting means. An apparatus for decoding a disk-shaped recording medium. 3. An information signal to be supplied is recorded by a recording device as a run-length encoded signal on a groove of a disc-shaped recording medium in which auxiliary information is formed as pre-pits at predetermined intervals on land portions. A disc-shaped recording medium decoding device configured to read the recorded coded signal from the disc-shaped recording medium and decode the coded signal obtained by the reading to obtain the information signal. A pre-pit position extracting means for extracting a signal position of a pre-pit signal from which the pre-pit is reproduced and read from the coded signal, and decoding the read coded signal by a process including a metric operation to obtain a decoded signal. And Viterbi decoding means for obtaining, based on the signal position information of the supplied prepit signal, the Viterbi decoding means. Decoding device of the disc-like recording medium, characterized in that for the entrained the coded signal of the pit signal and configured to stop the metric calculation. 4. An information signal to be supplied is recorded by a recording device as a run-length encoded signal on a groove of a disc-shaped recording medium in which auxiliary information is formed as pre-pits at predetermined intervals on land portions. A disc-shaped recording medium decoding device configured to read the recorded coded signal from the disc-shaped recording medium and decode the coded signal obtained by the reading to obtain the information signal. A pre-pit position extracting means for extracting a signal position of a pre-pit signal from which the pre-pits are reproduced and read from the coded signal; and Signal selecting means for selecting either the encoded signal or a predetermined signal value to obtain a selection signal; A Viterbi decoding means for decoding the run-length-encoded and recorded signal from the selection signal obtained by the selection means to obtain a decoded signal, and a disc-shaped recording medium characterized by comprising: Decoding device.