JPH0750545B2 - Disk playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a digital audio disc in which a digital audio signal of 2 channels is recorded and a digital data disc in which digital data other than the digital audio signal of 2 channels is recorded. And a disk reproducing device adapted to reproduce both of them.

“Background Technology and Its Problems” A system using an optical digital audio disc (called a compact disc) is a disc system capable of reproducing high quality stereo music. With this disk system, if it is possible to reproduce digital data such as data representing characters, display data, program data, etc. in addition to stereo music signals, by adding a display device, charts by graph graphics, statistics,
A playback device for visual information such as picture books using still images,
A video game device can be realized, and the application range of the compact disk system can be expanded. The current compact disk has a data storage capacity of about 500 Mbytes, which is an advantage over the storage capacity of conventional flexible disks.

In the case of a stereo music signal, one sample data is a 16-bit digital signal, and these 16 bits are divided into upper 8 bits and lower 8 bits, and the error correction code is encoded with 8 bits as 1 symbol. Has been done. 8 bits (ie 1 byte) for digital data
By using as a unit, it is possible to use the same error correction code as that of the stereo music signal described above.

During disk playback, uncorrectable errors may occur due to large scratches on the disk surface. A pointer indicating whether the reproduction data of the disk is correct data or error data is output together with the reproduction data. For stereo music signals, 1 in 16 bits
A pointer indicating the validity of data is added to each sample data. However, for digital data, it is necessary to add a pointer for each byte.

Accordingly, the object of the present invention is to provide a disk device adapted to reproduce one of a digital audio disk and a digital data disk, which can form a pointer adapted to the reproduced data of each disk. It is intended to provide a disk reproducing device.

Another object of the present invention is to provide a disk reproducing apparatus capable of reproducing a digital data and adding a pointer without substantially changing the structure of the compact disk reproducing apparatus.

[Summary of the Invention] The present invention relates to a digital audio disc in which one sample data of a digital audio signal is divided into two symbols, and data which has been subjected to error correction coding in units of the above symbols is recorded. A disk reproducing device in which each of the symbols is digital data, and both of the digital data disks in which the error-correction-coded data is recorded are reproduced, and the reproduced disk is a digital audio disk. Disc discriminating means (14) for discriminating whether the disc is a digital data disc or not, and decoding means for decoding the reproduced signal from the disc for error correction and outputting an error pointer according to the result of the error correction processing. (15, 16, 17) and the digital disc When an iodidisk is discriminated, a pointer indicating that one sample data is error data is output when at least one of two symbols forming one sample data contains an error after the error correction processing, and the disc discriminating means outputs a digital signal. When the data disk is discriminated, the disk reproducing apparatus is provided with a data output means (18) for outputting a pointer indicating the presence or absence of an error for each symbol after the error correction processing.

[Example] An example of the present invention will be described below. The data structure when the signal recorded on the disk is audio data (that is, the current compact disk) will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a data stream recorded on a compact disc. One frame is 588 bits of recorded data, and after the frame synchronization pulse FS of a specific bit pattern for each frame, a 3-bit DC suppression bit RB is provided, and after that, each 14 bits.
Bits 0 to 32 of data bits DB and 3 bits of DC component suppression bit RB are provided alternately. The 0th one of the data bits DB is called a sub-coding signal or a user's bit, and is used for disk reproduction control and related information display. The 1st to 12th, 17th to 28th data bit DBs are assigned to the main channel audio data, and the remaining 13 to 1
The 6,29th to 32nd data bit DBs are assigned to the parity data of the error correction code of the main channel. Each data bit DB is obtained by converting 8 bits of data into 14 bits by the 8-14 conversion during recording.

Figure 2 shows each data bit DB except the DC suppression bit.
Shows 8 bits and 98 frames are arranged in parallel in order. Subcoding signal P of 0 and 1 frames
˜W form a sync pattern which is a predetermined bit pattern. As for the Q channel, 16 frames on the terminating side of the 98 frames have CRC for error detection.
Code has been inserted.

The P-channel is a flag indicating a pose and music. The P-channel is a low level for music, a high level for pause, and a pulse of 2 Hz cycle in the lead-out section. Therefore,
By detecting and counting the P-channel, it is possible to select and play the designated music. The Q-channel can perform the same kind of control in a more complicated manner. For example, the information of the Q-channel is taken into the microcomputer provided in the disk reproducing device, and the music is immediately reproduced while the music is being reproduced. It is possible to select a random song. Other than this, R-channel to W-channel display the songwriter, composer, commentary, poem, etc. of the song recorded on the disc.
Used for audio commentary.

Of the 98 bits of the Q channel, the first 2 bits are used as the sync pattern, the next 4 bits are used as the control bits, the next 4 bits are used as the address bits, and the subsequent 72 bits are used as the data bits. , At the end, a CRC code for error detection is added. Data Bit 7
The track number code TNR and the index code X are included in the two bits. Track number code TNR is 0
The index code X can also change from 0 to 99, and the index code X can also change from 00 to 99. Further, as Q channel data, a time display code indicating the time of the song and pause, and a time display code displaying the absolute time that continuously changes from the beginning of the program area of the compact disk to the end on the outer peripheral side are included. Be done. Each of these time display codes is composed of a 2-digit minute, second, and frame code. One second is divided into 75 frames. In order to access the compact disc in units shorter than music, such as digital data, the above-mentioned time display code relating to absolute time is used.

In this embodiment, when the digital data is recorded as the main channel data, the data structure of the P channel and Q channel of the sub-coding signal is the same as that of the compact disk. FIG. 3 shows a recording format of digital data. Digital data has a unit of (588 × 4 bytes = 2352 bytes), and this unit is one block. In FIG. 3, the left channel and the right channel show the correspondence between the stereo music data and the sample data of the left and right channels. As described above, in the case of stereo music data, (6 × 2 × 2 = 24
(1 byte) data is recorded, so if digital data is recorded using the same signal format (Fig. 1) as stereo music data, 1 block (2352 bytes) will be recorded.
Are recorded from the 0th frame to the 97th frame.
Therefore, the digital data can be recorded without breaking the 98 frames of the change cycle of the sub-coding signal.

The first 1 byte of the 1-block digital data is a bit of all 0s, the subsequent 10 bytes is a bit of 1s, and the subsequent 1 byte is a bit of 0s. This 12-byte section is used as a header indicating the beginning of one block of digital data. After Hezda, 1 each
Byte minutes, seconds, sectors, and mode data are added. The minute, second, and sector are 1-block addresses, and the sector is 75 sectors and is 1 second like the frame. The mode data indicates the type of digital data of the block. Hezda,
Address (minute, second, sector), remaining 23 excluding mode
Digital data such as still image data is inserted into 36 bytes.

FIG. 4 shows the structure of an embodiment of the present invention. In FIG. 4, reference numeral 1 denotes a digital disc in which the digital signal of the above-mentioned format is spirally recorded. The disk 1 is rotated by a spindle motor 2. In this case, the spindle motor 2 is controlled by the spindle servo rotation 3 so that the disk 1 rotates at a constant linear velocity.

4 indicates an optical head, and the optical head 4
Has a laser source for generating a laser beam for reading, an optical system such as a beam splitter and an objective lens, and a light receiving element for the laser beam reflected by the disk 1. The optical head 4 can be moved in the radial direction of the disk 1 by a thread feed motor 5. The thread feed motor 5 is driven by a thread drive circuit 6. Further, the optical head 4 is displaceable in two directions, a direction orthogonal to the signal surface of the disk 1 and a direction parallel to the signal surface, and is controlled so that focusing and tracking of laser light during reproduction are always good. To be done. For this purpose, the focus servo circuit 7
And a tracking servo circuit 8 are provided.

The reproduction signal of the optical head 4 is supplied to the RF amplifier 9. The optical head 4 is provided with, for example, a focus error detecting section formed of a combination of a cylindrical lens and a four-divided detector, and a tracking error detecting section using three laser spots. RF amplifier 9
Is output to the clock extraction circuit 10. The output (data and clock) of the clock extraction circuit 10 is supplied to the frame synchronization detection circuit 11. The digital signal recorded on the disk 1 is EFM-modulated. EFM modulation is preferred for 8 bits of data with 14 bits (ie
This is a method of block conversion into a 14-bit) pattern in which the minimum inversion time of the modulated signal is long and the low frequency component is small. The digital demodulation circuit 12 is configured to demodulate EFM. The bit clock extracted by the clock extraction circuit 10 and the frame synchronization signal detected by the frame synchronization detection circuit 11 are supplied to the digital demodulation circuit 12 and the spindle servo circuit 3.

In the digital demodulation circuit 12, the sub-coding signal is separated, and this sub-coding signal is supplied to the system controller 14 via the buffer memory 13. A CPU is provided in the system controller 14, and the system controller 14 performs the rotation operation of the compact disc 1, the thread feeding operation, the reading operation of the optical head 4, and the like.
It is configured to be controlled by. A control command is supplied to the system controller 14 via an interface 19 described later. That is, the system controller 14 controls the reading of a desired digital signal from the compact disc 1 using the sub-coding signal.

The main digital data output from the digital demodulation circuit 12 is supplied to the RAM 16 and the error correction circuit 17 via the RAM controller 15. The RAM controller 15, the RAM 16 and the error correction circuit 17 perform the processing of removing the time base fluctuation and the error correction, and the main digital data is taken out from the output. The output of the RAM controller 15 is supplied to the demultiplexer 18. Demultiplexer 18
Is controlled by whether the disc being played is a compact disc for stereo music signals or a digital data disc for storing digital data.
The system controller 14 switches the output system path. As an example, the control channel of the Q channel of the sub-coding signal recorded in the lead intra of the disc 1 identifies whether the disc being reproduced is for stereo music signals or for storing digital data. It

The output path selected during digital disk playback is
The data conversion circuit 19 is connected. A reproduction sub-coding signal is supplied from the buffer memory 13 to the data conversion circuit 19 together with the reproduction digital data, and the reproduction data is converted into a serial signal form. This serial signal is supplied to the interface 20, and the data for the system controller 14 is supplied from the microcomputer system 21 via the interface 20. The microcomputer system 21 specifies a read address and supplies a drive control signal such as a start signal to the interface 20 and the system controller 14 in addition to the read address.

An interpolation circuit 22 is connected to the output path of the demultiplexer 18 selected when the disc being reproduced is for a stereo music signal, and error data that cannot be corrected is corrected. It is divided into left and right channels by the interpolation circuit 22, and the data of each channel is converted into an analog signal by the D / A converters 23L and 23R, and taken out to the output terminals 25L and 25R via the low-pass filters 24L and 24R, respectively.

In one embodiment of the present invention, the buffer memory 13 removes the time-axis variation of the sub-coding signal. This time base correction is similar to that performed by the RAM controller 15 and the RAM 16 for the digital signal of the main channel. In other words, the RAM controller 15
A light clock that is synchronized with the playback signal is formed from the detected frame synchronization signal, and by this light clock,
When writing a digital signal to the RAM 16 and reading the digital signal from the RAM 16, the read clock formed from the output of the crystal oscillator is used. The write clock and the read clock are used for writing and reading the sub-coding signal to and from the buffer memory 13. Therefore, the sub-coding signal read from the buffer memory 13 does not include the time axis fluctuation, and the time relationship with the digital signal of the main channel is prevented from changing due to this time axis fluctuation.

In one embodiment of the present invention, first, the microcomputer system 21 executes a read instruction for a predetermined address. This address is the code itself for displaying the absolute time of the Q channel, and the address is supplied to the system controller 14 through the interface 20. The system controller 14 controls the thread drive circuit and moves the optical head 4 to a position near the target reading position while watching the sub-coding signal reproduced by the optical head 4. In this example, because the reproduced sub-coding signal contains an error, the set sub-coding signal is not reproduced and the access operation is not terminated. I'm trying to get started. Then, when the reproduced sub-coding signal coincides with the designated address, or the reproduction is started from the position of the correct sub-code signal in the vicinity to count the frame synchronization signal. I'm trying to catch the block that does.

The RAM controller 15, RAM 16 and error correction circuit 17 described above
The error correction performed by the method will be described. FIG. 6 shows the decoder written according to the order of error correction for ease of understanding. FIG. 5 shows the configuration of an encoder for data recorded on the master disk when the disk is created.

In FIG. 5, 31 indicates a scramble circuit. This scramble circuit 31 has even sample data L ₆ n, R ₆ n, L ₆ n + 2, R ₆ n + 2, L _{6 for} each of the L channel and the R channel.
n + 4, R ₆ n + 4 and odd sample data L ₆ n + 1, R ₆ n + 1, L ₆ n
+ 3, R ₆ n + 3, L ₆ n + 5, R ₆ n + 5, interleaved and 1
It transforms the position of the symbol in the frame. 1
The 16 bits of the sample data are bisected into the upper 8 bits and the lower 8 bits, and the 8 bits are treated as one symbol to be encoded. 12 sample data (24 symbols) of music data is supplied to the scramble circuit 31, and 24 symbols output from the scramble circuit 31 are C ₂
It is supplied to the encoder 32, and the (28,24) Reed-Solomon code is encoded.

The parity of 4 symbols generated at the output of this C ₂ encoder 32
The data of 24 symbols is supplied to the interleave circuit 33. The interleave circuit 33 is provided in order to improve the burst error correction capability by separating the recording positions of 28 symbols contained in one C ₂ code sequence. The 28 symbols output from the interleave circuit 33 are supplied to the C ₁ encoder 34, and the (32,28) Reed-Solomon code is encoded. 32 symbols including four parities formed by the C ₁ encoder 34 are supplied to the delay circuit 35. The delay circuit 35 is for delaying only the odd symbols in one frame. A sub-coding signal of 1 symbol is added to 32 symbols output from the delay circuit 35, and then EFM modulation is performed. At the time of this EFM modulation, a frame synchronization signal is added to form a recording signal as shown in FIG.

When recording digital data, 24 symbols of 1 bit of 8 bits are supplied to the scramble circuit 31 in place of the 12 sample data of the digital audio signal, and the same encoding as described above is performed.

The reproduced signal from the disk is EFM demodulated, supplied to the decoder shown in FIG. 6 and subjected to error correction processing. 32 symbols in one frame are supplied to the delay circuit 45, only even symbols are delayed, and the delay given by the delay circuit 35 of the encoder is canceled and supplied to the C ₁ encoder 44, (32,2
8) Error correction of the Reed-Solomon code is performed, and the corrected data and pointer are supplied to the deinterleave circuit 43. The deinterleave circuit 43 performs a process of restoring the interleave performed by the interleave circuit 33, and the output of the deinterleave circuit 43 is supplied to the C ₂ decoder 42.

The pointer of each symbol generated by the C ₁ decoding is also subjected to the same deinterleaving process as the data in the deinterleave circuit 43. Deinterleave the RAM controller 15
Is generated by generating a predetermined address for the RAM 16. The pointer formed by the C ₁ decoder 44 is written in a partial memory area of the RAM 16 and is subjected to the same address control as data. In the C ₂ decoder 42, the (28,24) Reed-Solomon code is decoded using the C ₁ decoding pointer. C
₂ The error-corrected data and pointer from the decoder 42 are supplied to the descramble circuit 41. The descramble circuit 41 performs an operation reverse to that of the scramble circuit 31, and at the output thereof, reproduced data of 24 symbols is obtained in the original order.

A decoding method performed by the C ₁ decoder 44 and the C ₂ decoder 42 will be described. First, the C ₁ decoder 44 performs the following decoding. Syndrome calculated from playback data S ₁
And the pointer passed to the C ₂ decoder 42 is P ₁ .

(1) When the syndrome S ₁ has no error, no correction is made and (P ₁ = 0).

(2) When a single error is detected from the syndrome S ₁ , correct the single error and set it as (P ₁ = 0).

(3) When a double error is detected from syndrome S ₁ Correct the double error and set (P ₁ = 1).

(4) When an error of triple or more is detected from the syndrome S ₁ , do not correct and set (P ₁ = 1).

That is, the C ₁ decoder 44 performs double error correction, and at that time, there is a possibility of incorrect correction, so (P ₁ = 1)
Then check again with C ₂ decryption.

The decoding in the C ₂ decoding device 42 will be described below. The syndrome calculated by the C ₂ decoder 42 is S ₂ , the pointer information from the C ₁ decoder is P ₁ , N (P ₁ ) is the pointer of C ₁ out of 28 symbols input to the C ₂ decoder 42 The number of P ₁ , L (P ₁ = S ₂ ) is the number of pointers P ₁ of C ₁ that coincides with the error location calculated from the syndrome S ₂ , and P ₂ is the interpolation flag passed to the interpolation circuit 22.

(1) When it is judged from the syndrome S ₂ that there is no error, it is set to (P ₂ = 0) without correction.

(2) When a single error is detected from the syndrome S ₂ , perform single error correction and set it as (P ₂ = 0).

(3) When a double error is detected from the syndrome S ₂ (i) When N (P ₁ ) ≦ 4 and L (P ₁ = S ₂ ) = 2, double error correction is performed, and (P ₂ = 0).

(Ii) N (P ₁ ) ≦ 3 and L (P ₁ = S ₂ ) = 1 or N
When (P ₁ ) ≦ 2 and L (P ₁ = S ₂ ) = 0, no correction is made and (P ₂ = 1).

(Iiii) In cases other than (i) and (ii), no correction is made and P ₁ is directly used as P ₂ .

(4) When triple or more errors are detected from the syndrome S ₂ (i) When N (P ₁ ) ≦ 2, no correction is made and (P ₂
= 1).

(Ii) In cases other than the above, no correction is made and P ₁ is directly used as P ₂ .

The above-described decoding operation is performed for every 8-bit symbol.
When even one of the two symbols forming one sample data of the digital audio signal includes an error, the sample data needs to be interpolated by the interpolation circuit 22. Therefore, if the pointers of the two symbols forming the same sample data are P _2A and P _2B , the pointer P _AB associated with the sample data is the OR output of the pointers P _2A and P _2B . On the other hand, since the digital data is in units of 8 bits, pointers P _2A and P
_2B is used as a pointer for each symbol.

By setting the memory area for the pointer of the RAM 16 as a unit of 8 bits, from the RAM controller 15, as shown in FIG. 7, together with the two symbols W _A and W _B forming one sample data, 8 bits. The pointer information of is output. Of pointer information of the 8 bits, the most significant bit is a pointer P _AB sample data units, the next bit is a pointer P _2B symbol W _B, further, the next bit is a symbol W _A The pointer is P _2A . During the reproduction of the digital audio disc, the interpolation circuit 22 controls whether or not to perform interpolation by looking at the pointer P _AB . At the time of reproducing the digital data disk, the data conversion circuit 19 converts the pointers P _2A and P _2B into serial data together with the digital data.

As a result of the decoding performed by the RAM controller 15, the RAM 16 and the error correction circuit 17, even when the pointer extracted to the output does not correspond to the presence or absence of a symbol error,
This invention can be applied.

As an example, the case where the 3-bit pointers D ₁ , D ₂ , and D ₃ are output as follows will be described.

When both symbols W _A and W _B have no error, (D ₁ =
D ₂ = D ₃ = 0). When both symbols W _A and W _B have an error, (D ₁ = D ₂ = D ₃ = 1). Symbol W _A
Is error-free and symbol W _B has error, (D ₁
= 1, D ₂ = 1, D ₃ = 0). When the symbol W _A has an error and the symbol W _B has no error, (D ₁ = 1, D ₂ = 0, D ₃
= 1).

When such pointers D ₁ , D ₂ and D ₃ are generated, the pointers P _A and P _B for digital data can be formed by the logic circuit shown in FIG. The pointer D ₁ is supplied to the NOR gate 52 via the inverter 51, and the pointer D ₂ is supplied to the NOR gate 52.
52 and the OR gate 53, the pointer D ₃ is supplied to the NOR gate 52 and the OR gate 54, the OR gate 54 takes out the pointer P _A , and the OR gate 53 takes out the pointer P _B. With this logic circuit, the pointers P _A and P _B correspond to the presence or absence of errors in the symbols W _A and W _B. For example, when (D ₁ = D ₃ = 1, D ₂ = 0), (P _A = 1, P _B = 0
0).

[Effect of the Invention] According to the present invention, when both the digital audio disk and the digital data disk are played back, a pointer can be formed in sample data units for digital audio data. In this case, the pointer can be formed on a symbol-by-symbol basis. Further, by using a pointer memory of a plurality of bit units in which the same address control is performed for both digital audio data and digital data, it is not necessary to change the pointer processing on both sides, and therefore the current compact It is possible to reproduce the digital data by using the hardware of the disk reproducing device almost as it is.

[Brief description of drawings]

1 and 2 are schematic diagrams used for explaining a recording signal of a compact disk, FIG. 3 is a schematic diagram showing a data structure when recording digital data, and FIG. 4 is an embodiment of the present invention. FIG. 5, FIG. 5 is a block diagram used for explaining the error correction encoder, FIG. 6 is a block diagram used for explaining the error correction decoder, and FIG. 7 is a schematic line used for explaining one embodiment of the present invention. 8 and 9 are block diagrams used to explain another embodiment of the present invention. 1 ... Digital disk, 4 ... Optical head, 15 ... RAM controller, 16 ... RAM, 17 ... Error correction circuit, 19 ... Data conversion circuit, 20 ... Interface, 22 ... Interpolation circuit, 23L, 23R …… D / A converter, 32
…… C ₂ encoder, 34 …… C ₁ encoder, 42 …… C ₂ decoder, 44 ・ ・ ・
… C ₁ decoder.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G11B 20/18 574 D 9074-5D E 9074-5D

Claims (1)

[Claims] 1. A digital audio disc in which each piece of sample data of a digital audio signal is divided into two symbols, and data subjected to error correction coding in units of the symbols is recorded, and each of the symbols. Is a digital data, and is a disk reproducing device for reproducing both of the digital data disks recorded with the error-correction-coded data, and whether the reproduced disk is the digital audio disk or not. , A disc discriminating means (14) for discriminating whether or not the disc is a digital data disc, and a decoding means for decoding a reproduced signal from the disc for error correction and outputting an error pointer according to the error correction processing result. (15, 16, 17) and the above digital disc identification means When the disc is discriminated, a pointer indicating that the 1-sample data is error data is output when at least one of the 2 symbols constituting the 1-sample data contains an error after the error correction processing, and the disc is output. A disc reproducing apparatus comprising: a data output unit (18) for outputting a pointer indicating the presence or absence of an error for each symbol after the error correction processing when the discriminating unit discriminates a digital data disc.