JPH0463475B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-speed playback method for a disk, and the number of track pitches to be transferred is varied so that it is small on the outer circumference side of the disk and large on the inner circumference side, and the playback section is intermittently transferred, thereby performing a search. Provides a high-speed disc playback method that allows the playback speed ratio in the mode to be the same anywhere in the radial direction of the disc, provides natural playback sound, and allows the desired playback position to be found in the time required for search. The purpose is to

Conventionally, we have developed a compact disk in which digitized two-channel audio signals are recorded on a spiral track as the presence or absence of pits, and a laser beam is irradiated onto this disk to detect the presence or absence of pits as a change in the strength of the reflected laser beam. There are disk playback devices that read and play back audio signals. Since this playback device uses laser light to play back the disc without contacting the disc, it is possible to move the laser light in the radial direction of the disc to perform interlaced playback along a spiral track. For this reason, conventionally, the laser beam is transferred (jumped) to a track on the outer (or inner) side of the disk every time a certain period of playback is performed.
There is a disc playback device that searches for a desired audio recording position by repeating this process to perform high-speed playback of the disc.

FIG. 1 schematically shows a playback trajectory during a search by a conventional disc playback device. In the figure, 1 is a disk, and a digital signal is recorded on a spiral track 2 on the disk 1 from the inner circumferential side to the outer circumferential side. During normal playback, the spiral track 2 is sequentially scanned from the inner circumference side to the outer circumference side, but for example, when a section _T1 is played back for a certain period of time during a fast forward search, the laser beam is scanned, for example, at five track pitches. It is transferred (jumped) to the outer circumferential side, and then section _T2 is reproduced.
Thereafter, sections T ₂ , T _{3 .} . . , T ₇ are reproduced in the same manner.

However, since disc 1 is played back at a constant relative linear velocity, the playback on the inner circumference of the disc is the ratio of the time required to normally play back sections _T1 to _T2 and the time required for fast forward search playback during this period. The speed ratio differs from the reproduction speed ratio on the outer circumference side of the disk between sections T ₆ to _{T 7} , and the reproduction speed ratio on the outer circumference side is larger than the reproduction speed ratio on the inner circumference side.
For this reason, there are drawbacks in that the reproduced sound at the time of search becomes unnatural, and it is difficult to find a desired reproduction position based on the search time.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described with reference to FIG. 2 and the following figures.

FIG. 2 shows a block system diagram of an embodiment of a device to which the method of the present invention is applied. In the figure, reference numeral 1 denotes a compact disc on which digitized two-channel audio signals are recorded from the inner circumference to the outer circumference of a spiral track, indicating the presence or absence of pits. This disk 1 is supported by a rotating shaft 6 of a motor 5 and driven to rotate. Further, 7 is an optical system, and the laser beam emitted from this optical system 7 is reflected by the disk 1 and enters the optical system 7 again. This reflected light is detected by an optical sensor built into the optical system 7, and the intensity of the reflected light, which changes depending on the presence or absence of pits on the disk 1, is converted into an electrical signal. Also,
The optical system 7 is also provided with a feed servo circuit and a tracking servo circuit 8. This feed/servo and tracking servo circuit 8 detects a tracking error from the output signal of the optical sensor of the optical system 7, and according to this tracking error signal, the optical system 7
The laser beam emitted by the disk 1 is displaced in the radial direction of the disk 1, and the laser beam is automatically adjusted so as to scan the track 2 of the disk 1. When the tracking adjustment mechanism that displaces the laser beam exceeds a certain displacement, the entire optical system 7 is displaced in the radial direction of the disk 1 by the feed/servo, so that the optical system 7 is always located within the tracking adjustment range. be adjusted.

The signal read and reproduced by the optical sensor of the optical system 7 is supplied to the demodulation circuit 9. The demodulation circuit 9 first synchronizes the bits of the reproduced signal, extracts the bits, and demodulates the obtained signal by EFM. The demodulated signal is supplied to a frame synchronization circuit 10. The frame synchronization circuit 10 operates based on the bit clock (BCL) from the demodulation circuit 9, detects a frame synchronization signal included in the demodulation signal, performs frame synchronization of this demodulation signal, and performs frame synchronization of the demodulation signal immediately after the frame synchronization signal of each frame. The user's bits are supplied to the microcomputer 11, and the subsequent 192 data bits and 64 error correction bits are supplied to the correction circuit 12. The correction circuit 12 de-interleaves the 256-bit signal supplied from the frame synchronization circuit 10 using the bit clock (BCL) as a reference, and also detects and corrects code errors. Thereafter, the correction circuit 12 takes out a digital signal whose time axis fluctuations have been corrected based on the clock signal (CL) supplied from the clock generation circuit 13, and outputs it to the next stage left/right separation circuit via the output terminal 14. do.

Further, a signal indicating the amount of displacement of the entire optical system 7 is output from the feed servo and tracking servo circuit 8 and is supplied to the motor drive servo circuit 15.
Further, a bit clock (BCL) obtained by the demodulation circuit 9 is supplied to the motor drive servo circuit 15. The motor drive servo circuit 15 controls the rotation speed of the motor 5 according to the amount of displacement of the entire optical system 7, and furthermore, the frequency of the bit clock (BCL) is set to a constant value based on the clock signal (CL) from the clock generation circuit 13. The rotation speed of the motor 5 is controlled so that As a result, the disc 1 is played back at a constant relative linear velocity. The microcomputer 11 controls the feed servo and tracking servo circuit 8 and the motor drive servo circuit 15 according to the scanning signal supplied from the input terminal 16, and also processes the user's bits supplied from the frame synchronization circuit 10. .

FIG. 3 shows a schematic configuration of the system of the present invention. In the figure, information signals are recorded on disk 1 as spiral tracks. This disk 1 is scanned at a constant relative linear velocity by reproduction units 7, 8, 9, and 10, and information signals are read and reproduced. The detection means A detects the position in the radius of the disk 1 of the track currently being scanned by the reproducing sections 7, 8, 9, 10 based on the signals from the reproducing sections 7, 8, 9, 10.
This detected position is supplied to setting means B, where the number of track pitches is set according to the position. The control means C controls the playback sections 7, 8, 9, and 10 to scan and play back the inner or outer tracks by the number of track pitches set by the setting means B after scanning the track currently being scanned for a certain period of time. do.

The microcomputer 11 executes the program shown in FIG. 4A when an operation signal supporting the fast forward search mode is supplied from the input terminal 16.

In FIG. 4A, step 20 is first executed and a scanning duration Tl (Tl is, for example, 80 msec) is set in a variable TM functioning as a timer. This variable TM is automatically subtracted by "1" every unit time during the execution of the process described later. Next, in step 21, the value (ATIME), which is the absolute address of disk 1 and represents the elapsed time of the recording program area of the disk, is taken in from the user's bits supplied by the frame synchronization circuit 10, and the value (ATIME) is taken in as a variable.
Transferred to ATIME. This variable ATIME is set to constants AT1, AT2, AT in steps 22 to 24.
It is compared with 3 people. The constant AT1 is set to the same value (ATIME) representing the elapsed time at the radius r ₁ of the disk 1 shown in FIG. 5, and the constants AT2 and AT3 are set to the values at the radii r ₂ and r ₃ , respectively. The same value as (ATIME) is set. Therefore, in steps 25 to 28, the disk 1
When a track on the inner circumference of radius _r1 is played, the variable N indicating the number of jump track pitches is set to "5".
is set, and when the tracks from radius r ₁ to radius r ₂ are played, the variable N is set to "4" and the radius
When the tracks from _r2 to radius _r3 are played back, the variable N is set to "3", and when the tracks on the outer periphery from radius _r3 are played back, the variable N is set to "2".

After the variable N is set, in step 29, the process moves to step 30, where the value of the variable TM becomes zero.
At step 30, a control signal for moving the laser beam one track pitch in the outer circumferential direction is output and supplied to the feed servo and tracking servo circuit 8. Thereafter, in step 31, the value of variable N is decreased by "1". The above step 30 is executed until the value of the variable N is determined to be zero in step 32. The processes of steps 20 to 32 are repeatedly executed as long as it is determined in step 33 that the mode is the fast forward search mode.

Therefore, as shown in FIG. 5, the radius r ₁ of disk 1
On the inner circumference, after section _T1 is played back, the tracks on the outer circumference of 5 track pitches are scanned and the section T1 is played back.
T ₂ is played. Further, in the radius _r1 to _r2 , for example, after the section _T2 is reproduced, the tracks on the outer periphery of the four track pitches are scanned, and the section _T3 is reproduced. Also,
For example, in the radius r ₂ to r ₃ , after reproducing section T ₃ , the tracks on the outer periphery of the 3 track pitches are scanned and the tracks are scanned to the section T ₄ .
is played. Furthermore, on the outer periphery of radius _r3 , for example, after reproducing section _T5 , the tracks on the outer periphery of two track pitches are scanned, and section _T6 is reproduced.

Here, when playing the track at the position of radius r, the time required for disk 1 to rotate once is Tr.
(Tr is a function of the radius r), the time required to jump by one track pitch is Δt, and the number of track pitches to be further jumped is N, then the playback speed ratio M _F in the fast forward search mode is expressed as follows.

M _F = N・T _r +Tl/Tl+N・Δt...(1) In equation (1), the predetermined value Tl is 80 msec, and the relative linear velocity when playing disc 1 is 1.3 m/sec.
Assume that the time Δt is negligibly small, and the radii r ₁ to _{r 3} are optimally selected. In this case, the relationship between the playback speed ratio M _F and the radius r in the fast forward search mode is as shown by the solid line I in FIG.
Even if the radius r of is changed, the playback speed ratio M _F remains approximately "8".

Next, when an operation signal supporting the reverse search mode is supplied from the input terminal 16, the microcomputer 11 executes the program shown in FIG. 4B. In the program shown in Figure 4B, the variable N is set to ``6'' in step 34, which corresponds to step 25 in Figure 4A.
is set, and similarly, in steps 35 to 37 corresponding to steps 26 to 28, the variable N is set to "5",
"4" and "3" are respectively set. Also step 3
At step 38 corresponding to step 0, a control signal for moving the laser beam in the inner circumferential direction by one track pitch is output.
In step 9, it is determined whether the mode is reverse search mode. The steps of this reverse search mode program other than those described above are exactly the same as the program shown in FIG. 4A, and their explanation will be omitted.

Here, playback speed ratio in reverse search mode
M _R is expressed as follows.

M _R =N・Tr+Tl/Tl+N・Δt...(2) The relationship between the reproduction speed ratio M _R and the radius r in this reverse search mode is as shown by the solid line in Figure 6B, and the speed ratio M _R is always It will be about "8".

In this way, the playback speed ratio in the search mode of the disc 1 is approximately the same no matter which part of the disc 1 from the inner circumference side to the outer circumference side is being scanned. Therefore, the reproduced sound in this search mode becomes natural, and it becomes possible to search for a desired reproduction position based on the time required for the search.

In the above embodiment, the current scanning position is detected by importing the value (ATIME) representing the elapsed time recorded on the disk, but there are other ways to detect the current scanning position.
The current scanning position may be detected by a signal from the servo and tracking servo circuit 8 or a signal obtained by detecting the position of the optical system 7 itself, and is not limited to the above embodiment.

In addition to compact disc playback devices, the method of the present invention can be applied to any playback device that reads information magnetically or electrostatically from a disk, as long as it plays back the disk at a constant relative linear velocity. It may be applied, and is not limited to the above embodiment.

As described above, the high-speed reproduction method of a disk according to the present invention is such that a disk on which information signals are recorded on a spiral track is scanned sequentially and intermittently at different tracks at a constant relative linear velocity by a reproducing unit, thereby reproducing information signals intermittently. In a high-speed playback method for discs that read and play back at high speed, the number of track pitches to be transferred is varied in the radial direction of the disk so that the number of track pitches is small on the outer circumference of the disk and large on the inner circumference, and the playback section is intermittently transferred. Since the playback speed ratio is set within a certain range even at the position, the playback sound in search mode can be made natural, and the desired playback position can be found based on the time required for search. It has features such as being able to

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining the playback locus in the conventional fast-forward search mode, and FIG. 2 is a block system diagram of an embodiment of a device to which the method of the present invention is applied.
FIG. 3 is a diagram showing a schematic configuration of the system of the present invention, and FIGS. 4A and 4B are flowcharts of each embodiment of a program executed by the microcomputer shown in FIG.
FIG. 5 is a schematic diagram for explaining the playback locus in the fast-forward search mode of the present invention, and FIGS. 6A and B are relationship diagrams between the playback speed ratio and the disk radius in the fast-forward search mode and reverse mode, respectively. be. 1... Compact disk (disk), 2...
...track, 7...optical system, 8...feed/servo and tracking servo circuit, 10...frame synchronization circuit, 11...microcomputer, 1
5...Motor drive servo circuit, 16...Input terminal, 20-39...Step, A...Detection means,
B... Setting means, C... Control means.

Claims (1)

[Claims] 1. A high-speed reproduction method for a disc in which an information signal is recorded on a spiral track, and a reproduction unit sequentially and intermittently scans different tracks at a constant relative linear velocity to read the information signal intermittently and reproduce it at high speed, After reading and reproducing the information signal for a certain period of time in the reproducing section, the number of track pitches to be transferred is varied in the radial direction of the disk so that the number of track pitches to be transferred is small on the outer circumferential side of the disk and large on the inner circumferential side, and the reproducing section is intermittently transferred. A high-speed playback method for a disk characterized in that the playback speed ratio is within a fixed range at any position on the disk.