JPH0370307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a scanning speed detection method for a disc playback device, and more particularly, to a scanning speed detection method for a disk playback device that detects the scanning speed during disk playback.

2. Description of the Related Art Conventionally, there has been a disc playback device for playing back a disc on which digital audio signals have been recorded.
A digital audio signal is recorded on the above disk at a constant linear velocity, and the disk playback device compares the synchronization signal reproduced from the disk with a reference frequency signal to determine that the scanning speed is constant (same as the linear velocity of the disk). The speed of the disk rotation motor is controlled to ensure that

Problems to be Solved by the Invention The linear velocity of a disc is approximately constant within a single disc, but this linear velocity is standardized to be 1.20 to 1.40 m/sec, and the linear velocity of each disc is within this standard. It can be any value within. As described above, the permissible range of linear velocity is wide, and the scanning speed of the disc reproducing apparatus also changes depending on the linear velocity of the disc to be reproduced.

Conventional disc playback devices do not detect scanning speed, and when scanning speed is required, e.g.
The average value of the disk linear velocity of 1.3 m/sec is used, and the actual scanning speed is ±10 from the above value.
The problem was that there was an error of 1.5% and the accuracy was poor.

For this reason, for example, during high-speed search playback, the number of track pitches calculated using the above scanning speed in the radial direction of the pickup disk includes an error of up to ±7.7%, and the large error causes a long search time. There was a problem.

SUMMARY OF THE INVENTION Therefore, the present invention provides a scanning speed detection method for a disc playback device that solves the above problems by measuring the scanning time of one track including the program start position on the disc and detecting the scanning speed of the disc. purpose.

Means for Solving the Problems FIG. 1 shows the overall configuration of the system of the present invention. In the figure, the recorded signal on disk 1 is transmitted to playback mechanisms 2, 3,
4, 5, 21, 24, and 25, and demodulated by the demodulation circuit 7. The microcomputer 19 has playback mechanisms 2 to 5, 21,
24, 25 and demodulation circuit 7, and generates a control signal to control the servo circuits 17, 1.
8, 20, 22, and regenerating mechanism 2 to 5, 2
1, 24, and 25 are controlled. The search means A operates the microcomputer so that the playback mechanisms 2 to 5, 21, 24, and 25 search for the program start position on the disk 1, and then the measurement means B measures the scanning time of one track including the program start position. The scanning speed of the disk is detected by calculating using this scanning time in the detection means C. The program start position of the disk 1 searched by the detection means A is the diameter of the disk 1 50 ⁺⁰ _-0.4 mm position, and there is almost no error in diameter. The measuring means B obtains the scanning time of one track including this program start position. The length of one track can be determined with high accuracy because there is almost no error in the diameter, and the scanning time obtained by calculating this length and the scanning time in the detection means C becomes highly accurate.

Embodiment 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, 1 is an eight-to-fourteen modulation (hereinafter referred to as (EFM)) digitalized two-channel audio signal.
This is a compact disc in which signals are recorded from the inner circumference to the outer circumference of the spiral track. After the disk 1 is installed in a mounting section (not shown) of a playback device, it is driven by a drawer motor 2 and loaded into a predetermined position.
It is supported and rotated. Further, 5 is a pickup of the optical system, and the laser beam emitted from the pickup 5 is reflected by the disk 1 and enters the optical system again. This reflected light is detected by an optical sensor built into the pickup 5, 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.

The signal read by the optical sensor of the pickup 5 is amplified by an amplifier 6 and then supplied to a demodulation circuit 7, where it is EFM demodulated. The 192 data bits and 64 error correction bits of each frame of the demodulated signal are supplied to a correction circuit 8. The correction circuit 8 uses the RAM 9 to de-interleave the 256-bit signal, and further,
Code errors are detected and corrected, and digital signals of the right and left channels whose time bases have been corrected are extracted. This digital signal is converted into an analog audio signal by a D/A converter 10, and unnecessary high-frequency components are removed from the right channel and left channel audio signals by low-pass filters 11 and 12, respectively, and amplified by amplifiers 13 and 14. After that, terminals 15 and 16
output from each.

Further, the read signal from the pickup 5 is supplied to a focus servo circuit 17 and a tracking servo circuit 18, respectively, and the user's bits from the demodulation circuit 7 are supplied to a microcomputer 19. The focus servo circuit 17 displaces the objective lens of the optical system in the pickup 5 in response to the read signal and the control signal from the microcomputer 19 to focus the laser beam on the recording surface of the disk 1. The tracking servo circuit 18 detects a tracking error from the read signal, and further displaces the laser beam emitted by the pickup 5 in the radial direction of the disk 1 in accordance with the control signal from the microcomputer 19, so that the laser beam performs recording on the disk 1. Automatically adjusts to scan tracks.

Further, the radial servo circuit 20 drives the radial motor 21 in accordance with the scanning track information from the tracking servo circuit 18 and the control signal from the microcomputer 19 to move the pickup 5 in the radial direction of the disk 1. The disk servo circuit 22 rotates the disk motor 3 in response to an error signal obtained by phase comparison between the frame synchronization signal from the demodulation circuit 7 and the clock signal from the microcomputer 19, so that the disk 1 is reproduced at a predetermined linear velocity. Automatically adjust so that When the sensor 24 detects that the disk 1 is mounted, the drive circuit 23 drives the drawer motor 2 in response to a control signal from the microcomputer 19 to load the disk. The sensor 25 supplies a detection signal to the microcomputer 19 when the pickup 5 is at the innermost scanning position of the disk 1. A signal generated by operating the operation panel 26 is supplied to the microcomputer 19, which controls the operation of the disc playback device.A display signal from the microcomputer 19 is also supplied to the display 27, which controls the operation of the disc playback device. Displays the playback position, track number, etc.

Next, the processing executed by the microcomputer will be explained.

When the microcomputer 19 is supplied with a detection signal detected by the sensor 24 when the disk 1 is attached to the attachment section (not shown) of the playback device,
The process shown in FIG. 3A is executed. In FIG. 2A, a control signal is first supplied to the drive circuit 23 to drive the drawer motor 2 to load a disk (step 30). When loading of the disk is completed, the radial motor 21 is driven and the pickup 5 is moved toward the inner circumference of the disk 1 until the sensor 25 generates a detection signal (step 31). Thereafter, the focus servo, tracking servo, and radial servo are activated (step 32), and reproduction of the digital signal recorded on the disk 1 is started.

By starting the playback described above, the TOC (Table of Contents) recorded on the lead intratrack on the inner circumferential side of the program start position on disk 1 is played back (step 33), and as a result, the table of contents recorded on disk 1 is played back (step 33). The A times at the start positions of all songs are read and stored. The above A time represents the playback time from the program start position, corresponds to the absolute address of disk 1, and is recorded in the user's bit during the program recording period of disk 1. Next, the diameter of disk 1
A program start position located at a position of 50 mm and having an A time value of zero is searched for (step 34). When the program start position is reproduced, the scanning speed, that is, the linear speed of the disk 1 is detected in step 35.

In step 35, the process shown in FIG. 3B is executed. In step 36 of FIG. 3B, the counter
_NL is reset. Furthermore, the pick-up 5 is forcibly moved (jumped) one track pitch inward from the program start position (step 3).
7), you will be prompted to continue playing. Thereafter, the counter N _L counts up the frame synchronization signal reproduced at a frequency of 7350 Hz, and when the program start position where the A time is zero is detected (step 38), the process moves to step 39. At step 39, the coefficient value of the counter N _L is read out.
Thereafter, the scanning speed V _L of the playback device, that is, the linear velocity of the disk 1 is calculated using the following equation (step 4).
0).

V _L = π・T _F・D _O /N _L ...(1) However, T _F is the frame period (=1/7350), and D _O is the diameter of the program start position of disk 1 (=49.8
mm).

After determining the playback speed V _L in this manner, the process shown in FIG.

where the diameter at the program start position is 50 ⁺⁰ _-0.4 mm
In other words, since the error is as small as 49.8mm±0.4%, the track length of one round of disk 1 including the program start position can be determined with high accuracy with an error of about 0.4%, and this track length can be calculated using the scanning time (N _L /T _F ), the scanning speed obtained by dividing by ) will be of high accuracy.

When, for example, a desired song number is input from the operation panel 26 in FIG. 2 and high-speed search playback is instructed, the microcomputer 19 executes the process shown in FIG. 4. In FIG. 4, at step 41, time A in the user's bits reproduced from disk 1 is read and stored in variable An.
Thereafter, the process moves to step 42, where the number of tracks N _T is determined using the following equation.

However, P is the track pitch of disk 1 (=
1.6μm), At is the A time of the search target position, A time of the song start position of the input song number, V _L is the scanning speed, calculated using equation (1), and R _O is the radius of the program start position. (=24.9mm).

When the number N _T of tracks to be transferred is determined by equation (2), it is determined whether the number N _T is positive or negative (step 43), and if it is positive, the process moves to step 44, and if it is negative, the process moves to step 45. When it is determined in step 44 that the number of tracks N _T is greater than "256", the tracking servo is turned off and the pick-up 5 is fed at high speed toward the outer circumference of the disk 1 by the radial motor 21 (step 46). The number of times the envelope of the read signal of the pickup 5 exceeds a predetermined level (number of transferred tracks) is counted, and when this count value becomes equal to the number of tracks N _T (step 47), the tracking servo is turned on and the normal playback state is entered. (step 48), and the process moves to step 41. Further, if the number of tracks N _T is less than "256", the number of tracks N _T is compared with "4" (step 49),
If it is larger than "4", the laser beam of the pickup 5 is shifted (jumped) to the outer circumferential side by (N _T -2) tracks (step 50), and then the process moves to step 41. If it is smaller, the normal playback state is entered (step 51), and the values of the variable A _o and the A time At of the target position are compared (step 52), and if they do not match, the process moves to step 41.
Processing ends when a match occurs.

Also, in step 45, the number of tracks N _T is
256'', the tracking servo is turned off and the pick-up 5 is fed at high speed toward the inner circumference of the disk 1 (step 53), and when the number of phase shift tracks at this time becomes equal to the number of tracks N _T ( At step 54), the tracking servo is turned on and the normal playback state is established (step 55).
The process moves to step 41. Also, the number of tracks N _T
If is greater than "-256", the laser beam from the pickup 5 is shifted (jumped) to the inner circumferential side by (N _T -2) tracks (step 56), and the process then proceeds to step 41.

When performing high-speed search playback using the process shown in _FIG .
%, the number of tracks obtained from equation (2)
N _T can be determined accurately. Therefore, the number of tracks
Almost no time is required to correct the error in N _T , and the search time is shortened.

Effects of the Invention As described above, the scanning speed detection method of the disc playback device according to the present invention detects the scanning speed of the disc by measuring the scanning time of one track including the program start position of the disc. The track length can be determined with high accuracy, thereby increasing the accuracy of the scanning speed, and has the advantage that, for example, the search time during high-speed search playback can be shortened.

[Brief explanation of drawings]

Figure 1 shows the overall configuration of the system of the present invention, Figure 2 shows the overall configuration of the system of the present invention.
The figure is a block system diagram of an embodiment of an apparatus to which the method of the present invention is applied, and FIGS. 3 and 4 are flowcharts of the processing executed by the microcomputer shown in FIG. 2, respectively. 1...Disk, 5...Pickup, 18...
...Tracking servo circuit, 19...Microcomputer, 20...Radial servo circuit, 30
~56...Step.

Claims (1)

[Claims] 1. In a scanning speed detection method of a disk playback device that scans a disk on which information signals are recorded on a spiral track at a constant linear velocity at a scanning speed equal to the linear velocity to read and reproduce the information signals, the program start of the disk. Scanning of a disc playback device, characterized in that: searching for a position, measuring the scanning time of a track that goes around the disc including at least the program start position, and detecting the scanning speed of the disc using the scanning time. Speed detection method.