JPS626444A - Optical disk reproducing device - Google Patents

Abstract

PURPOSE:To improve the detecting accuracy of a mistrack by actuating a correcting function when a difference between a timer value and time information read out from a disk exceeds a threshold to control the reproducing position of the disk. CONSTITUTION:When a stylus jump is generated, the difference between the value of the timer 44 and the time information read out from the disk increases and exceeds the threshold, so that mistrack is detected and correcting operation of the disk reproducing position is executed, regarding the value of the timer 44 at that time as an objective value. If an endless loop is formed on the disk 10, the timer 44 value is counted up, but the read-out time information is held at the same value. Thereby, the difference is gradually increased, and when the difference exceeds the threshold, mistrack is detected and the operation for advancing the disk reproducing position is executed by regarding the timer value as the objective value. Consequently, the detecting accuracy of mistrack can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for correcting mistracking such as needle skipping when it occurs in an optical disc reproducing device such as a compact disc.

[Conventional technology]

In optical disc playback devices such as compact discs, when needle skip occurs due to external vibrations, etc., the needle jump is detected and the disc playback position is returned to or near the position before the needle jump, thereby significantly reducing the needle jump. It can prevent flying. Conventionally, needle skipping has been detected based on time information periodically obtained from the disk itself.

FIG. 2 shows a conventional needle skip correction circuit. In FIG. 2, recorded information on a disk 10 is detected by an optical head 12, and time information ATI)IE is extracted by a subcode reproducing circuit 14.

The extracted time information ATTHE is temporarily held in the memory of the controller 16, and then new time information ATIHE is stored.
' is read from memory at the same time as it is input. The trigger 38 determines the difference between the current time information ATIHE' and the previous time information ATIHE.

When the disk is being traced normally, the interval of the time information ATIME is constant, so the difference is small and always constant, but when needle skipping occurs, the difference becomes large. The absolute value of the determined difference is taken by an absolute value circuit 40. The comparator 42 compares the output of the absolute value circuit 42 with a predetermined threshold value TH, so that the output of the absolute value circuit 42 becomes equal to the threshold value T.
When it exceeds H, a needle skip detection signal is output. This results in
The controller controls the optical head 12 using the previous time information ^TI.
Control it to the ME position (or control it to a position advanced by a certain amount of time) to enter the play state. In this way,
Fixed needle skipping.

However, the conventional device has the following drawbacks.

■Depending on the scratches on the disk, for example, an optical track that should originally be spiral-shaped may become optically resembling a closed ring (endless loop). In this state, the conventional device uses the previous time information ^TIME and the current time information ATI.
Since HE' is the same or there is only a slight difference, it is not judged as a mistrack, and the same track is simply traced repeatedly, making it impossible to extract from that track.

■ If the time information ATrHE is unreadable due to scratches on the disc, but the audio data has been successfully obtained by data correction, the difference between the current and previous time information ^TIME may occur even though there is no need to return the disc playback position. This results in unnecessary correction operations.

(2) Since the reading interval of the time information ATIHE is fixed, the threshold value TH cannot be lower than the interval, and there is a limit to the accuracy of mistrack detection.

[Problem that the invention seeks to solve]

This invention aims to provide an optical disc playback device that solves the problems encountered with conventional technology, such as being able to extract even when an endless loop is formed due to scratches on the disc. be.

[Means for solving problems]

This invention provides a timer, calculates the difference between the timer value and time information read from the disc, and when this difference exceeds a threshold value, it is determined that a mistrack has occurred, and a correction function is activated to adjust the disc playback position. It was designed to be controlled.

[Effect]

According to the solving means of the present invention, when the 1-race of the disc is being performed normally, the difference between the timer and the read time information is small, so the reproduction continues as is.

Additionally, when needle skipping occurs, the difference between the timer and the read time information increases and exceeds the threshold, so mistracking is detected and the disc playback position is corrected using the timer value at that time as the target value. An action is taken.

In addition, if an endless loop is formed on the disk, the timer value advances, but the read time information remains the same value, so the difference gradually increases, and if it exceeds the same value, a mistracking occurs. is detected, and if the timer value at that time is set as the target value, an operation is performed to advance the disc playback position.

In addition, if the time information cannot be read due to scratches on the disk, but if the audio data is normally obtained by data correction, the timer will continue to operate, and the next time the time information is read, the timer and time information will be If the difference remains small, no unnecessary corrective action is taken.

In addition, since the difference between the timer and the time information read from the disk is calculated, if the minimum unit of the timer is made smaller, the difference can be found in more detail, and the accuracy of mistrack detection can be improved by reducing the threshold value. can be done.

〔Example〕

An embodiment of this invention is shown in FIG.

In FIG. 1, recorded information on a disk 10 is recorded by an optical head 1.
2, and the time information ^T is detected by the subcode reproducing circuit 14.
The IME is extracted and the controller 16 and subtractor 3
8 is input.

The timer 44 measures all play state transitions, such as when the disc playback device transitions to a play state (from a stop state to a play state, from a momentary search state during play to a play state, etc.). ), the time information read from the disk at that time is set as an initial value, and the timer is started from that value. The value RTrHE of the timer 44 is input to the subtracter 38.

The subtracter 38 calculates the difference between the value RTIHE of the timer 44 and the time information ATrHE read from the subcode reproducing circuit 14. The absolute value of the determined difference is taken by an absolute value circuit 40. The comparator 42 compares the difference signal output from the absolute value circuit 40 with a threshold value TH (for example, 0.5 seconds) at the timing when the time information ATIME is obtained (approximately every 13 m5 during normal operation). And the difference signal threshold T
When it exceeds H, a needle skip detection signal is output.

When the needle skip detection signal is input to the controller 16,
The reproduction position of the optical head 12 is controlled using the value RTTHE of the timer 44 at that time as a target value.

FIG. 3 shows the operation of the embodiment shown in FIG. When the play state is entered from the stop state, search state, etc., time information ATIHE read from the disc 10 at that time is preset in the timer 44. The timer 44 starts counting using this preset value as an initial value. Then, the value RTIHE of the timer 44 is subtracted from the time information ^TIME read from the disk 10, and if the subtracted value exceeds the threshold TH, mistracking (repeated tracing of the same track due to needle skipping or endless loop formation) is detected. etc.), and the reproduction position is search-controlled using the value RTTHE of the timer 44 at that time as a target value. Therefore, if the needle jumps, it will be returned to near its original position. Furthermore, in the case of repeated tracing of the same track, since the target position RTIME is at a position ahead of that track, the playback position is moved forward and is forcibly removed from the endless loop.

If the subtraction value is smaller than the threshold TH, it is determined that the trace is normal, and the track number and time are displayed.

Also, due to scratches etc. on the disc 10, the time information ATIH
If E is not read out, the reproduction is continued as is, and when the time information ATIHE is read out again, the same operation as described above is performed depending on the difference from the value RTIHE of the timer 44.

FIG. 4 schematically shows the operation when the needle jumps forward. When the play state is entered, the time information A at that time
TIHE is preset as the initial value of the timer 44. (Indicated by ■.) Therefore, the time information ATTHE and the value RTIHE of the timer 44 increase in parallel (■). If forward needle skipping occurs due to external vibrations, scratches, etc. (◎→＠
), then when the time information ATIHE is obtained (■), it is compared with the value RTII4E of the timer 44, and the difference is the vR value T.
When it exceeds H, the timer value RTIM at that point (◎)
Perform search operation (return) using E as the target value (◎→■
). When the search is completed (■), the play operation is resumed from that position (■). Further, the time information ATIHE at the time of transition to the play operation is preset as the initial value of the timer 44 (■), and the timer operation is reproduced (■).

FIG. 5 schematically shows the operation when the backward needle jumps (the same applies to repeated tracing of the same track by forming an endless loop). When the play state is entered, the time information ATIHE at that time is preset as the initial value of the timer 44 (■). Therefore, time information AT
T) IE and the value IME of the timer 44 increase in parallel (■). When backward needle skip occurs due to external vibration or scratches (◎→@), the next time the time information ATIHE is obtained (◎), it is compared with the value RTTHE of the timer 44, and if the difference exceeds the threshold TH, Timer value R at that point (◎)
Perform a search operation (advance) using TIME as the target value (
■→■). When the search operation is completed (■), the play operation is restarted from that position (Q). Also, the time ATIHE at the time of transition to this play operation is set to the first IFlrr1 of the timer 44.
(5)) and restarts the timer operation (■).

Fig. 6 schematically shows a state in which the time information is temporarily unreadable due to a scratch on the disc, etc., but the audio data is correctly obtained by data correction. When the state changes, the time information ATIHE at that time is preset as the initial value of the timer 44 (◎). Therefore, the time information ATIHE and the value RTIHE of the timer 44 increase in parallel (0). Scratches on the disk, etc. When the time information ATrHE becomes unreadable (◎), the comparison with the value RTIHE of the timer 44 is stopped. Then, when the reading of the time information ATIHE is restarted (@), the comparison with the value RTIHE of the timer 44 is stopped. A comparison is made. At this time, if tracing was performed correctly even while the time information could not be read, the difference between the time information ATIHE and the value RTIHE of the timer 44 after resuming reading is smaller than the threshold TH, so that reproduction is not possible. The play state continues without performing any position correction operation (◎).The timer 44 also continues to operate (■).

〔Effect of the invention〕

As explained above, according to the present invention, a timer is provided, the difference between the value of the timer and the time information read from the disk is determined, and if this difference exceeds a threshold, it is determined that there is a mistrack, and a correction function is activated. Since the disc playback position is controlled by operating the disc, it is possible to correct not only forward needle skips but also backward needle jumps such as repeated tracing of the same track due to endless loop formation.

In addition, if the time information cannot be read due to a scratch on the disk, but the audio data is normally obtained by data correction, the timer continues to operate. The difference remains small, and unnecessary corrective actions are avoided.

In addition, since the difference between the timer and the time information read from the disk is calculated, if the minimum unit of the timer is made smaller, the difference can be found in more detail, and the same value can be made smaller to improve mistrack detection accuracy. can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a block diagram showing a conventional device. FIG. 3 is a flowchart showing the operation of FIG. 1. FIG. 4 is a diagram schematically showing the operation of the device shown in FIG. 1 when the needle jumps forward. FIG. 5 is a diagram schematically showing the operation of the apparatus shown in FIG. 1 when the backward needle jumps. FIG. 6 is a diagram showing the operation when time information becomes temporarily unreadable. 10...disk, 12...-optical head, 44...
timer. Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] A timer; a circuit for extracting time information from a playback signal of an optical disc; a circuit for determining a difference between the timer value and the time information; 1. An optical disc playback device comprising: a circuit for detecting a disc playback position and controlling a disc playback position.