JPS6376157A - Disk reproducing device - Google Patents

Abstract

PURPOSE:To prevent the feeling of the omission of data by stopping the reading of main information data stored in a storing means and reading the main information data before the track jumping from when a track jumping is generated until an original track is returned. CONSTITUTION:While a track N is reproduced, when a track jumping occurs at a track M and thereafter, the track N is returned, the reproducing data of the track N are written into a buffer memory 24 before the track jumping, the reproducing data of the track M are written after track jumping and the reproducing data of the track N are written after the original track N is returned. At this time, without reading the reproducing data of the track M written into the buffer memory 24, before the track jumping occurs, the reproducing data of the track N written into the buffer memory 24 are read. The sample frequency of an R address is made lower than usual, and the period to read the reproducing data of the track M is interpolated by the reproducing data of the track N before the track jumping.

Description

[Detailed Description of the Invention] [Object of the Invention (Field of Industrial Application)
The present invention relates to a disc reproduction HH system, and particularly relates to a system in which a reproduction signal is not interrupted even if a track jump occurs during reproduction.

(Prior Art) As is well known, in the field of audio VI equipment, audio signals are digitized using PC-1 (pulse code modulation) technology in order to record and reproduce them with as high density and high fidelity as possible. Digital recording and reproducing systems that convert data into data, record it on a recording medium such as a disk or magnetic tape, and reproduce it are now in widespread use. Of these, compact discs, which use discs as recording media, are currently the mainstream, with a 12 cl diameter disc on which a bit string corresponding to digitized data is formed and this is read optically. .

On the other hand, a disc playback device that plays back a compact disc as described above moves an optical pickup containing a semiconductor laser, a photoelectric conversion element, etc. in a linear tracking manner from the inner circumference side of the disk toward the outer circumference side. C is designed to read data recorded on a compact disc by rotating the compact disc at constant linear velocity (CLV).

Here, digital audio data (main information data) obtained by converting an analog audio signal into 8-bit PCM is recorded on the compact disc. In this case, the digital audio data has a unit called one frame, which is a unit of 24 symbols in which one symbol is 8 bits, and data is recorded in the form that this frame is repeated.

Specifically, as shown in FIG. 10, 24 symbols of digital audio data (hereinafter referred to as words) W are supplied to the C2 series parity generation circuit 12 after passing through the scrambler 11, and are converted into 4 symbols ( Parity data Q for 02 series error correction of 8 bits per symbol is generated. Then, the word W of 24 symbols and the parity data Q of 4 symbols are transferred to the interleaving circuit 13.
After passing through the C1 series parity generation circuit 14, the parity data P for 01 series error correction of 4 symbols (8 bits per symbol) is generated.

After that, 32 symbols of data consisting of 24 symbols of word ~■ and 4 symbols of parity data P and Q are as follows:
After passing through the one frame delay circuit 15, 8-bit subcode data is added. The above subcode data and 32 symbols of data are subjected to EFM (pulse code modulation) modulation, with 3 margin bits interposed between each modulated 14-bit symbol, and 24 bits at the beginning. A frame synchronization signal is added, and the 588-bit data thus obtained is recorded on the disk as one frame.

In this case, the pit clock is 4.32 MHz, so 136 μsec (7.35 kHz) per frame.
z) will be recorded on the disc. Furthermore, in the above subcode data, one subcode frame is composed of 98 frames, and each subcode frame has 75H.
z (13,3m5ec) is recorded on the disk.

On the other hand, the above-mentioned disc playback device is compatible with compact discs.
Digitized data read from °EFMt! ! U.A.
After L, it is separated into a word component including parity data P and Q and a subcode data component. Of these, the word component is processed by the one-frame delay circuit 16 as shown in FIG.
The parity data P is supplied to the C1 series error correction circuit 17 via the parity data P, and error correction processing is performed based on the parity data P.

Thereafter, the 24-symbol word ~■ and the 4-symbol parity Q are passed through the dinterleave circuit 18 to the C2
The data is supplied to the sequence error correction circuit 19, and error correction processing is performed based on the parity data P.

The 24-symbol word W is then supplied to an A/D (digital, 'analog) conversion circuit system and an analog signal processing circuit system (not shown) via the descrambler 20, and is reproduced into an audio signal.

In addition, the above subcode data component is P per frame.
, Q, R, S, T, U, V, and W, and as mentioned above, one subcode frame is composed of 98 frames. In the subcode data, the first two frames (frame numbers rOJ and "1") in one subcode frame are subcode frame synchronization patterns 3o and 31, and the remaining 96 frames are essentially It is a data component.

Here, the subcode data P is provided for distinguishing between songs and within a song, and for example, "1" represents an interval between songs;
0'' indicates the middle of a song.The above subcode data Q is called address data, and in the program area of the disc (radius 25 to 58 mm), it is used to indicate the song number of a famous song recorded on the disc. (TNO), section number (index), elapsed time, etc., and in the lead-in area of the disc (radius 23 to 25 mm), it is TOC (Table of Contents) data that indicates the start address of the famous song. .

Note that the other 6-bit subcode data R-W is currently specified for transmission of color graphics image data.

Here, a read/write memory (hereinafter referred to as RAM) is used for the processing described in FIG. 11 performed in the disk reproducing apparatus. That is, the EFM demodulated word components are sequentially stored in the RAM, subjected to C1 and C2 sequence error correction processing, and then read out from the RAM and output to the A/D conversion circuit. It is something that

In this case, there are four types of addresses to be supplied to the RAM: That is, the W address for writing EFM demodulated data to RAM, RAM1. : I Address 01 to read out C1 series data from the loaded data in order to detect errors in the C1 series data, and to load and read data into and from RAM in order to correct detected error data. 02 for reading out C2 series data to detect errors in the C2 series data from the written data, and also for fixing to and reading from RAM in order to correct the detected error data.
This is an R address for reading data from the RAM for use by the A/D conversion circuit.

When an optical pickup reads data by tracing tracks formed on a compact disc, as in the above-mentioned disc playback device, vibrations applied from the outside may cause the pickup element installed in the optical pickup to as the objective lens is flown from the currently tracing track to another track,
So-called ]-rack skipping may occur. When such a situation occurs, the address data included in the subcode data has traditionally been used to automatically return the objective lens to the original track and continue the playback operation. It is being done to

Specifically, as shown in FIG. 12(a), suppose that the objective lens is tracing track N and is blown to track M by external vibration at time t1. Then, the data of track M is read through the objective lens, the distance to the original track N is calculated based on the address data in the subcode data, and at time t2, the objective lens returns to the original track N. It is something that will be moved.

In this case, the data to be subjected to C1 sequence error correction processing is
It changes as shown in FIG. 12(b). In addition, in Fig. 12<1)), if one frame of data is considered as 6 symbols of UO-US, the data is UO, . . .
US, 2Uo,..., 2US.

3UO1..., 3U5. ... are sent in this order.

At this time, if the objective lens successfully jumps from track N to track M at the frame break, then C1
No errors are detected in the sequence.

Then, when the above data is subjected to dinterleaving processing, the data array becomes as shown in FIG. 12 (C),
When C2 series error correction is performed in this state, in a frame in which track N data and track M data are mixed (frames indicated by "x" in the figure), C2 sequence error correction is performed.
Two series of errors are now detected. However, in frames in which track N data and track M data are not mixed (frames indicated by rOJ in the figure), no error is detected even if the data are from different tracks.

By the way, as mentioned above, the objective lens causes deviation and the track N after the dinterleaving process is
Error correction of the 02 series in a frame in which track M data and track M data are mixed has a high possibility of causing an error correction. Tying processing is commonly performed.

Therefore, the audio signal becomes as shown in Figure 13(a), but the audio signal obtained by playing back track M is short-lived, and even if it is output, it will only become noise, so in practice The data obtained by playing track M is also muted, and as shown in FIG. 13(b), all data from the time a track jump occurs until the track returns to the original track is muted. I try to avoid it.

By the way, when a track jump occurs and an operation is performed to return to the original track again, the detection of whether or not a track jump has occurred, the detection of whether or not the original track has been returned, etc.
This is done by reading the address data in the subcode data. In order to read the address data in the subcode data, it is necessary to read the subcode frame synchronization signal generated from the subcode frame synchronization pattern So, 31.

For this reason, as shown in FIG. 14(a), for example, if the subcode frame synchronization signal can be read immediately when jumping to track M, it is possible to return to the original track N in a short time. As shown in b), the muting period of the audio signal can also be shortened. However, it is extremely rare for track skipping to occur at such ideal timing; for example, as shown in Figure 15(a).
As shown in the figure, if the subcode frame synchronization signal has just been generated when jumping to track M, or if an error occurs in the subcode data read after returning to the original track N, In this case, the muting period of the audio signal becomes extremely long, as shown in FIG. 2(b).

As a result, a problem arises in that the sound is cut off and the listener feels uncomfortable.

(Problem that Flming is trying to solve) As mentioned above, in conventional disc playback devices, when a track skip occurs, data is muted until playback of the original track is resumed. If it takes a long time to return to playback of the original track, there is a problem in that sound breaks occur.

Therefore, this invention was made in consideration of the above circumstances, and provides an extremely good disc that does not make the user feel that data is missing until playback of the original track is resumed when a track jump occurs. The purpose is to provide a playback device.

[Structure of the Invention] (Means for Solving the Problems) That is, the disc reproducing device according to the present invention returns main information data obtained from a pickup element to the original track after the pickup element skips a track. The main information data stored in the storage means is sequentially stored in a storage means having a data storage capacity greater than the amount of main information data to be reproduced within the time required for The main information data stored in the storage means is read out sequentially after a corresponding period of time has elapsed before returning to the track, and the main information data stored in the storage means is read out sequentially after the pickup element skips the track and returns to the original track. The main information data stored in the storage means is read out from the storage means before the pickup element causes track skipping.

(Function) According to the above configuration, reading of the main information data stored in the storage means is prevented during the period from when the pickup element skips the track until it returns to the original track, and the pickup element Since the main information data stored in the storage means is read out before a track skip occurs, when a track skip occurs, the user does not feel that data is missing until playback of the original track is resumed. It is something that can be done like this.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In FIG. 1, 21 is a disk from which data recorded by an optical pickup 22 is read. The data read by this optical pickup 22 is processed by an EFM demodulation circuit 23 into an EFMt
After being lm'd, it is separated into a word component including parity data P and Q and a subcode data component.

Among these, the word component is refined into a buffer memory 24 composed of a RAM, and after absorbing the time axis jitter component, it is supplied to a correction circuit 25 to be used as a CI.

C2 series error correction processing is performed. Then, the data for which the error correction process has been completed is sequentially written into the buffer memory 24 again.

Here, the buffer memory 24 has a data storage capacity greater than the amount of data that can be reproduced within the time required for the objective lens (not shown) of the optical pickup 22 to return to the original track after skipping a track. have.

The buffer memory 24 sequentially reads out the written data to the output circuit 26 after the time required for the objective lens to return to the original track after track skipping has elapsed. That is, the buffer memory 24 has a buffer capacity that is greater than the time required for the objective lens to return to its original track after it skips a track.

The data read out to the output circuit 26 is D
The signal is supplied to an analog playback system (not shown) via the /A (digital/analog) conversion circuit 27 and output terminal 28 for playback.

On the other hand, the subcode data component output from the EFM demodulation circuit 23 is demodulated by the subcode demodulation circuit 29, and then the address data component is sent to the track jump detection circuit 29.
0 so that track skipping can be detected. This track jump detection circuit 30 detects a track jump in the buffer 7 memory 24 when a track jump is detected.
Address circuit 3 that generates read/write addresses of
1 and the output circuit 26 as described below,
This is to deal with truck jumping.

That is, let us consider a case where a track skip occurs in track M while track N is currently being reproduced, and then track N is restored. Then, the buffer memory 24
The reproduced data of track N is applied before the track jump, the reproduced data of track M is written after the track jump, and the reproduced data of track N is written after returning to the original track N.

Therefore, when the stored contents of the buffer memory 24 are read out by generating the R address from the address circuit 31 at a normal sampling frequency, the audio signal is read out from the audio signal of the track N as shown in FIG. 2(a). The audio signal of track M (sample points are indicated by alphabets in the figure) is interposed in the signal (sample points are indicated by numbers in the figure).

Here, conventionally, the audio signal of track M is muted, but in this embodiment, as shown in FIG. 2(b), the playback data of track M written in the buffer memory 24 is muted. 1 in the buffer 7 memory 24 before a track jump occurs without reading it.
The sampling frequency of the R address for reading out the recorded playback data of track N is lowered than normal, and the period during which the playback data of track M should be read is interpolated with the playback data of track N before the track jump. .

Such control of the R address is performed using a first detection signal outputted from the track jump detection circuit 30, which indicates that a track jump has occurred, and a second detection signal, which indicates that the original track has been returned. This is done by the address circuit 31 receiving the detection signal.

In this case, the address circuit 31 selects an R address from which to read the stored data before the track jump occurs, which corresponds to the period between the generation of the first detection signal and the generation of the second detection signal. The sampling frequency is lowered to 1/2 of the normal frequency.

After returning to the original track in this manner, the address circuit 31 returns the sampling frequency of the R address to its normal value.

In addition, when the sampling frequency of the R address is lowered to 1/2 of the normal frequency as described above and the period during which the reproduced data of track M is to be read is interpolated with the reproduced data of track N before the track jump, as shown in FIG. As shown in (C),
By interpolating between the data of each sample point 2 to 20 using data generated by average value correction, pre-substitution correction, etc. (indicated by ◎ t in the figure), the sampling frequency of the R address is not substantially lowered. It may be done as follows.

Here, the address circuit 31, as described above,
The buffer memory 24 is controlled by generating addresses, CI, C2 addresses, and R addresses, but when a track jump occurs, W.

The state of each address CI, C2 and R is shown in FIG.

In other words, the time t1 to t when track skipping does not occur
3, the W, CI, C2, and R addresses are generated normally with a predetermined amount of buffer. Assume that a track skip occurs at time t4, and the track returns to the original track at time t9.

Then, in this case, until time t8, W, C1° C2, R
Each address is generated as usual.

Then, from time t9 when the original track is restored, that is, when the second detection signal is generated from the track jump detection circuit 30, to time t17 when the R address approaches the storage address of data on another track due to track jump. During this period, the address circuit 31 slows down the progress of the R address, that is, lowers the sampling frequency, to compensate for the read period of data on another track.

At time t18, the address circuit 31 generates an R address by skipping the address of the area where the data of the other track is stored, thereby stopping the reading of the data of the other track, and thereafter ~■.

Each address of CI, C2, and R is generated as usual.

In this case, as shown in FIG. 4, at state B (time t4) where track skipping occurs, the sampling frequency of the R address is lowered, and addresses in areas where data of other tracks are stored are skipped (time t4). t12), and at time t14 when the original track has been returned and the buffer capacity has returned to the state before the track jump, the sampling frequency of the R address may be returned to its original value.

Note that in the above example, the sampling frequency of the R address was lowered to 1/2 of the normal rate, but this
Of course, it may be changed as appropriate depending on the time required from the occurrence of track skipping to the time the track returns to the original 1~Rack. For example, if the time required to return to the original track after a track skip occurs is short, the time can be interpolated using a small amount of data, so if the sampling frequency is slightly lower than usual, On the other hand, if time is good, the sampling frequency may be significantly lower than usual.

Next, FIG. 5 shows another example for interpolating missing data between the occurrence of a track jump and the return to the original track. That is, assuming that data has been written in the buffer memory 24 as shown in FIG. 5(a), the shaded portion in the figure can be regarded as the data of track M, that is, the missing data. In this case, if we ignore the delay caused by the buffer memory 24,
As shown in FIG. 5(b), an R address is generated so that data 10 to 14 and data 15 to 19 stored in the buffer memory 24 are repeatedly read twice each before a track jump occurs, and the track is tracked. -1 data (missing data) is interpolated.

In addition, as shown in FIG. 6(a), the buffer memory 24
Assuming that data has been written in the buffer memory 24, as shown in FIG. Data 3 stored in memory 24
The data (missing data) portion of track M may be interpolated by generating R addresses such that addresses 0 to 34 are repeatedly read twice each.

Here, the number of repetitions of data before and after the missing data, the data length to be repeated, etc. can be changed as appropriate depending on the data missing time.

Next, the output circuit 26 receives the first and second detection signals output from the track jump detection circuit 30, and
As shown in FIG. 7(a), the zero-crossing point of the audio signal before track jump output from the D/A conversion circuit 27, and as shown in FIG. 7(b), the output from the D/A conversion circuit 27. The data read from the buffer 1 memory 24 is controlled so that the zero-crossing points of the audio signal after returning to the original track are connected continuously as shown in FIG. This is to avoid giving it a natural feel.

In this case, as shown in Figure 8(a), the audio signal before jumping to the track is faded out, and as shown in Figure 8(b), the audio signal after returning to the original track is faded in. The data read out from the buffer 7 memory 24 may also be controlled so that both audio signals are connected as shown in FIG.

Furthermore, as shown in No. 91 (a), the audio signal before jumping to the track is faded out, and as shown in FIG. 91 (b), the audio signal after returning to the original track is faded in, The data read out from the buffer memory 24 may be controlled so that both audio signals are connected in a cross-fade manner as shown in FIG. 2(C).

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] Therefore, as detailed above, according to the present invention, when a track skip occurs, the user does not feel the loss of data until the original track is resumed. A good disc playback device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing an embodiment of a disc playback device according to the present invention, FIGS. 2 to 4 are diagrams for explaining the operation of the same embodiment, and FIGS. 5 and 6 are FIG. 7 is a diagram for explaining other operation examples of the same embodiment, respectively.
9 to 9 are waveform diagrams for explaining the operation of the output circuit in the same embodiment, FIG. 10 is a block diagram showing the means for generating data to be recorded on a compact disc, and FIG. 11 is a diagram showing the configuration of a compact disc. 12 and 1 are block diagrams showing processing means for data read from
3 is a diagram for explaining the operation of the conventional disc reproducing apparatus, and FIGS. 14 and 15 are timing diagrams for explaining the problems of the conventional disc reproducing apparatus, respectively. DESCRIPTION OF SYMBOLS 11... Scramble part, 12... C2 series parity generation circuit, 13... Interleave circuit, 14...
・C1 series parity generation circuit, 15.16...1 frame delay circuit, 17...C1 series error correction circuit, 18
... Dinterleave circuit, 19... C2 series error correction circuit, 20... Descrambling section, 21... Disc, 22... Optical pickup, 23... E
FM demodulation circuit, 24...buffer 7 memory, 25...
Correction circuit, 26... Output circuit, 27... D/A conversion circuit, 18... Output terminal, 29... Subcode demodulation circuit, 30... Track jump detection circuit, 31...
・Address circuit. Applicant's agent Patent attorney Takehiko Suzue +1't lfi
d) Δ-(o++NFI size cofffufufufu

Claims (1)

[Claims] In a disc playback device that plays back a disc on which main information data is recorded together with address data via a pickup element, the pickup element detects that a track jump has occurred based on the address data obtained from the pickup element. a pickup control means for automatically returning the pickup element to the original track; and main information data obtained from the pickup element until the pickup element returns to the original track by the pickup control means after the pickup element causes a track jump. The main information data is sequentially stored in a storage means having a data storage capacity greater than the amount of main information data to be reproduced within the time required for reproducing the main information data, and the main information data stored in the storage means is stored after the pickup element causes track skipping. a first storage control means that sequentially reads the information after the time required for returning to the original track has elapsed; a second storage control means that prevents reading of the main information data and reads out the main information data stored in the storage means before the pickup element causes track skipping when reading the main information data corresponding to the period; A disc playback device comprising: