JPS6378379A - Disk reproducing device - Google Patents

Abstract

PURPOSE:To reproduce a signal by making a frame synchronizing signal and a window signal of information data recorded on a track N coincident with each other quickly while a pickup element returns from a track M to the track N to restore the pickup to the original track quickly if a track jump takes place. CONSTITUTION:When the generating timing of a frame synchronizing signal and the generating timing of a window signal (c) are made coincident, the frame synchronizing signal is used for data reproduction as a normal signal (shown in O mark). When an objective lens jumps to the track M at a time t11, a switch circuit 27 is controlled in the opposite switching state by using a detection signal from a track jump control circuit 33, an output of an AND circuit 28 goes to an L level and the counter 29 repeats circulated counts by self-clearing. Thus, the window signal synchronously with the generating timing of the frame synchronizing signal of the track N is kept to be generated without being affected entirely by the frame synchronizing signal (b) obtained from the track M.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention is applicable to optical CDs (compact discs), for example.
The present invention relates to a disk reproducing device of the above-mentioned type, and particularly relates to one that is capable of immediately reproducing data after returning to the original track when a track jump occurs during reproduction.

(Prior Art) As is well known, in the field of audio equipment, audio signals are digitized using PCM (Pulse Code Modification) technology in order to record and reproduce them with as high density and high fidelity as possible. Digital recording and reproducing systems have become widespread, in which the data is converted into a 3D image, recorded on a recording medium such as a disk or magnetic tape, and then reproduced. Of these, compact discs, which use discs as recording media, are currently the mainstream, with bit strings corresponding to digitized data formed on a 12 cm diameter disc and 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. The data recorded on the compact disc is read by rotating the compact disc at constant linear velocity (CLV).

Here, digital audio data (information data) formed by converting an analog audio signal into 8-bit PCM is recorded on the above-mentioned compact disc. In this case, the digital audio data consists of 24 symbols with 8 bits as one symbol. is a unit called 1 frame,
Data is recorded in such a way that this frame is repeated.

Specifically, as shown in FIG. 3, 24 symbols of digital audio data (hereinafter referred to as words) W are:
After the arrangement is changed by the scrambler 11,
The signal is supplied to the C2 series parity generation circuit 12 to generate 4 symbols (8 pits per symbol) of parity data Q for 02 series error correction. Then, the 24-symbol word W and the 4-symbol parity data Q are supplied to the C1-series parity generation circuit 14 after passing through the interleave circuit 13, and are used for 01-series error correction of 4 symbols (8 bits per symbol). Parity data P is configured.

After that, 32 symbols of data consisting of 24 symbols of word W and 4 symbols of parity data P and Q are 1
After passing through the frame delay circuit 15, 8-bit subcode data is added. Then, the subcode data and 32 symbol data are subjected to EFM (pulse code modulation) modulation, and the modulated 1
A 3-bit margin bit is inserted between each 4-bit symbol, and a 24-bit frame synchronization signal is added to the beginning, and the 588-bit data obtained in this way is recorded on the disk as one frame. It is something.

In this case, since the pit clock is 4.32MHz, 136μsec (7,35k
H2) will be recorded on the disc. Furthermore, in the above subcode data, one subcode frame is composed of 98 frames, and 75 frames per subcode frame.
It is recorded on the disk at Hz (13.3m5ec).

On the other hand, the disc reproducing apparatus EFM demodulates the digitized data read from the compact disc, and then separates the data into a word component including parity data P and Q and a subcode data component. Among these, the word component is the fourth
As shown in the figure, C
1 series error correction circuit 17, parity data P
Error correction processing is performed based on.

Thereafter, the word W of 24 symbols and the parity Q of 4 symbols are supplied to the C2 series error correction circuit 19 via the dinterleave circuit 18, and error correction processing is performed based on the parity data P.

The 24-symbol word W is converted into the original arrangement by the descrambler 20, and then is converted into the original arrangement by the descrambler 20.
It is supplied to the D (digital/analog) conversion circuit system and analog signal processing circuit system, and is reproduced into an audio signal.

In addition, the above subcode data component is P per frame.
, Q, R, S, ■, Ll, V, ~■. As mentioned above, one subcode frame is composed of 98 frames. Then, in the subcode data, the first two frames (frame numbers "O" and "1") in one subcode frame have subcode frame synchronization patterns So, S? The remaining 96 frames are the actual data components.

Here, the subcode data P is provided for distinguishing between songs and within a song, and for example, "1" represents an interval between songs, and 1
10 II indicates the middle of the song. The above subcode data Q is called address data, and in the program area of the disc (radius 25 to 58U+), each song number (TNO), section number (index), and elapsed time recorded on the disc is etc., and in the lead-in area of the disc (radius 23 to 25 square meters), there is a TOC (table table) indicating the start address of each of the above.
content) data.

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

Here, a read-out memory (hereinafter referred to as RAM) is used for the processing described in FIG. 4 performed by the disc reproducing apparatus. That is,
The EFM demodulated word components are sequentially written into the RAM and subjected to C1 and C2 sequence error correction processing, and then read out from the RAM and output to the A/D conversion circuit system. be.

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, the W address for reading C1 series data to detect errors in C1 series data from the data written to RAM, and for correcting detected error data. 01 address for writing to and reading from RAM, C from data written to RAM.
Address 02 is used to read C2 series data to detect errors in the 2 series data, and is used to write to and read data from RAM in order to correct detected error data. This is the R address for reading data.

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 A so-called track jump may occur, in which the objective lens as an object is skipped from the track it is currently tracing to another track. When such a situation occurs, the address data included in the subcode data has conventionally been used to automatically return the objective lens to the original track and continue the playback operation. things are being done.

Specifically, as shown in FIG. 5, when the objective lens is tracing track N, at time t.
1, it is assumed that the object is blown onto the track M due to external vibration.

Then, the data of track M is read through the objective lens, and based on the address data in the subcode data, it is detected that a track skip has occurred, and the distance to the original track N is calculated. , time t2
Then, the objective lens is returned to its original track N.

Here, if the objective lens causes a track jump from track N to track M, in order to read the address data in the subcode data of the data recorded in track M, the frame synchronization signal in the data in track M must be need to be detected.

In addition, when a disc playback device reads and plays back data recorded on a disc, it generates a window signal synchronized with a frame synchronization signal, and converts the obtained frame synchronization signal that substantially coincides with this wind signal into a regular Data is reproduced as a frame synchronization signal. In this case, since one frame of the window signal is 588 bits as described above, the bit clock is set to 588 bits.
It is counted by a digital counter, and a pulse is generated every time this counter counts 588.

In addition to being cleared by itself every 588 counts, this counter is also cleared by the frame synchronization signal obtained by playing the disc. For example, if the frame synchronization signal for multiple frames is lost due to dropout, etc. If a frame synchronization signal is obtained again after the frame synchronization signal has not been obtained, the window signal can be modified to synchronize with the frame synchronization signal.

By the way, as mentioned above, the conventional method detects the occurrence of track skipping by reading the address data in the subcode data of the data recorded on the disk, and returns the objective lens to the original track. Disc playback devices have the following problems.

That is, assume that while the objective lens is tracing track N, a frame synchronization signal for data recorded on track N is obtained at the timing shown in FIG. 6(a). Then, before the time t1 when the objective lens jumps to the track M, the frame synchronization signal generation timing and the wind signal generation timing shown in FIG. 6(C) coincide, so that this frame synchronization signal is used for data reproduction as a regular signal (indicated by Q in the figure).

In this state, the objective lens reaches track M at time t1.
6(b), the generation timing of the frame synchronization signal obtained by reproducing track M is different from the generation timing of the frame synchronization signal obtained by reproducing track N. Therefore, it will no longer match the wind signal.

Therefore, the counter is controlled to generate a window signal that matches the frame synchronization signal obtained by reproducing the track M, and as a result, at time t2 when a plurality of frames have passed, a wind signal that matches the frame synchronization signal is generated. is now generated, and now the address data in the subcode data of the data recorded on track M can be read for the first time, and it is possible to detect that a track jump has occurred.

For this reason, data for a plurality of frames will be ignored after the track jump occurs until the data on track M is reproduced.

Then, the data of track M is reproduced, and the distance to the original track N is calculated based on the address data.
Assume that the vehicle returns to track N at time t3. Then, in this case as well, similarly to the above, the time t when a plurality of frames have elapsed
4, a window signal that matches the frame synchronization signal is generated, and for the first time, the address data in the subcode data of the data recorded on track N can be read, and the track returns to the original track N. is what is detected.

Therefore, even when returning from track M to track N, a plurality of frames of data will be ignored before the data can be reproduced.

(Problems to be Solved by the Invention) As described above, in the conventional disc playback device, when a track jump occurs, by the time a wind signal matching the frame synchronization signal of that track is generated,
Since multiple frames of data are ignored, the audio signal obtained before the track jump and the audio signal obtained after returning to the original track become discontinuous, causing discomfort to the listener. have.

Therefore, this invention was made in consideration of the above circumstances, and when a track skip occurs, it is possible to quickly return to the original track and start playing it, and the user is notified that a track skip has occurred. It is an object of the present invention to provide an extremely good disc playback device that does not make users feel the sound.

[Structure of the Invention] (Means for Solving the Problems) That is, the disc playback device according to the present invention uses the information data of track M in a state where the pickup element jumps from track N to track M. In addition, the pickup element is returned from track M to track N without stopping, and the generation of the wind signal is continued from when the pickup element flies from track N to track M until it returns to the original track N. This is what I did.

(Function) According to the above configuration, when the pickup element returns from track M to track N, it is possible to quickly match the frame synchronization signal of the information data recorded on track N with the window signal. Now you can
When a track skip occurs, the original track can be quickly restored and played back, and the user can be prevented from feeling that a track skip has occurred.

(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, which is rotationally driven by a disk motor 22. As shown in FIG. The disc 21 is configured such that recorded data can be read by an optical pickup 23.

Here, the data read by the optical pickup 23 is subjected to EFM demodulation by the EFM demodulation circuit 24, and then supplied to the synchronization signal detection circuit 25, and frame synchronization is performed based on the pit clock PLCK supplied to the input terminal 26. A signal is detected. This frame synchronization signal is normally supplied to one input terminal of the AND circuit 28 via the switch circuit 21 which is in the illustrated switching state.

On the other hand, the pit clock P supplied to the input terminal 26
LCK is counted by counter 29.

This counter 29 performs a cyclic counting operation of 588 selections, and each time the count value reaches 588, it clears itself and outputs a carry signal to the window signal generation circuit 30. When the window signal generating circuit 30 is supplied with the carry signal, it generates a window signal that becomes H level with a predetermined width, and this window signal is sent to the other input terminal of the AND circuit 28 via the OR circuit 31. Supplied.

Therefore, when the frame synchronization signal obtained by reproducing the disc 21 and the window signal obtained from the window signal generation circuit 30 are generated in agreement, the AND circuit 28
The counter 29 is cleared by the output. That is, when the frame synchronization signal and the window signal are obtained in normal agreement, the timing at which the counter 29 is self-cleared and the timing at which it is cleared by the output of the AND circuit 28 are synchronized. It will happen...
Further, the frame synchronization signal output from the synchronization signal detection circuit 25 and the window signal output from the window signal generation circuit 30 are supplied to the counter 32.

This counter 32 counts the number of times the frame synchronization signal and runid signal do not match, and when the count value exceeds a predetermined value, it generates an H level signal to the OR circuit 31.

For this reason, for example, multiple 7L/- due to dropout etc.
If a frame synchronization signal is obtained after a frame synchronization signal is not obtained for a period of time, the counter 29 will be cleared by that frame synchronization signal, and from this point onwards, a window signal will be generated. Control is performed to synchronize the window signal with the frame synchronization signal.

Further, the data read by the optical pickup 23 is supplied to a track jump control circuit 33. This track jump control circuit 33 generates a signal, such as a tracking error signal, that can detect that the objective lens has crossed a track based on the signal output from the optical pickup 23, and based on the signal, When it is detected that a track jump has occurred, a detection signal is generated to the switch circuit 27, and the switch circuit 27 is controlled to a switching state opposite to that shown in the drawing.

In addition, the track jump control circuit 33 counts signals that can detect that the objective lens has crossed the track, and
The number of tracks crossed is detected, and based on the count value, the objective lens in the optical pickup 23 is controlled to return to the original track.

That is, when a track jump occurs, the objective lens is returned to the original track without reading the data of the track to which it jumped.

The operation of the above configuration will be described below. First, assume that while the objective lens is tracing track N, a frame synchronization signal for data recorded on track N is obtained at the timing shown in FIG. 2(a). Then, before the time t11 when the objective lens causes track jump to the trunk M, the frame synchronization signal generation timing and the wind signal generation timing shown in FIG. 2(C) coincide, so this frame synchronization signal is used for data reproduction as a regular signal (indicated by Q in the figure).

In this state, if the objective lens jumps to the track M at time t11, the detection signal output from the track jump control circuit 33 controls the switch circuit 27 to a switching state opposite to that shown in the figure, so the AND circuit 28 The output becomes L level, and the counter 29 repeats the cyclic counting operation by self-clearing.

Therefore, the window signal synchronized with the generation timing of the frame synchronization signal of the track N continues to be generated without being affected by the frame synchronization signal shown in FIG. 2(b) obtained from the track M.

Then, due to the action of the track jump control circuit 33, time t1
Assume that the objective lens returns to the original track N at step 2. Then, since the wind signal is generated at a timing synchronized with the frame synchronization signal of track N, when returning to the original track N, the frame synchronization signal and the wind signal are immediately matched, and the audio signal It will be possible to generate .

Therefore, according to the configuration of the above embodiment, when a track skip occurs from track N to track M, the data of track M is changed while keeping the wind signal corresponding to the generation timing of the frame synchronization signal of track N. Detect track skipping without reading the original tran 9. N
As a result, when returning from track M to track N, it is now possible to quickly match the frame synchronization signal of track N with the wind signal, and if a track jump occurs, it can be quickly restored to the original position. It is possible to return to the previous track and perform playback, and it is possible to prevent the user from feeling that track skipping has occurred.

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

[Effects of the Invention] Therefore, as detailed above, according to the present invention, when track skipping occurs, it is possible to quickly return to the original track and perform playback, so that the user does not have to worry about track skipping. Therefore, it is possible to provide an extremely good disc playback device that does not make you feel that something is wrong.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a disc playback device according to the present invention, Fig. 2 is a timing diagram for explaining the operation of the embodiment, and Fig. 3 is a generation of data to be recorded on a compact disc. Block configuration diagram showing the means, 4th
The figure is a block diagram showing the processing means for data read from a compact disc, Figure 5 is a diagram to explain track skipping, and Figure 6 is a timing diagram to explain problems with conventional disc playback devices. be. 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 unit, 21 .・EFM demodulation circuit, 25...
Synchronous signal detection circuit, 26... Input terminal, 27... Switch circuit, 28... AND circuit, 29... Counter, 30... Wind signal generation circuit, 31... OR circuit, 32... ...Counter, 33...Track jump 1
ull] circuit.

Claims (1)

[Claims] Reading the information data from a disk on which the information data is recorded divided into frame units each accompanied by a frame synchronization signal through a pickup element, detecting the frame synchronization signal from the read information data, and reproducing the information data. In a disc playback device that performs the following, a window signal synchronized with the frame synchronization signal is generated, and the frame synchronization signal generated substantially in agreement with the window signal is used as a regular frame synchronization signal to reproduce the information data. synchronization signal protection means, and in a state where the pickup element jumps from track N to track M, the pickup element is moved from track M to track N without using the information data of track M;
and a window signal control means for causing the frame synchronization signal protection means to continue generating the window signal from when the pickup element flies from track N to track M until it returns to the original track N. and is configured to quickly match the frame synchronization signal of the information data recorded on the track N with the window signal when the pickup element returns from the track M to the track N. disc playback device.