JPH058507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a disk rotation control device in a disk player such as an optical disk player.

Background Art and its Problems Signals such as video signals and audio signals are recorded in a spiral track on a disk as a signal recording carrier so that they can be reproduced by irradiation with a light beam. In general, a system that reads and plays back signals from a disk by sending a pickup that irradiates a light beam onto the disk while rotating the disk in the radial direction of the disk so that the light beam scans the track of the disk. It is possible to record a signal for a certain length of time on a disk with the smallest possible diameter, or to record a signal for the longest possible time on a disk of a certain diameter, without degrading the signal quality. To make this possible, signals are recorded on the disc so that the signal recording density on the track is constant in any radial direction of the disc, and correspondingly, in the player, the signal reading position by the pick-up on the disc is spiral. The number of rotations of the disk is changed in accordance with the track from which information on the disk is being read so that the disk moves at a constant linear velocity in the tangential direction of the shaped track.

In order to control the rotation of the disc in the player in this way, a signal generator such as a frequency generator that generates a signal with a frequency proportional to the rotation speed of the disk, and a signal generator with a variable frequency that determines the rotation speed of the disk are used. A reference clock generation circuit that generates a reference clock is provided, and the phase of the signal obtained from the signal generator and the reference clock is compared, and the comparison output determines the rotation speed of the disk at a constant ratio to the frequency of the reference clock. In addition to controlling the motor that rotates the disk so that the disc is connected, it also detects the track where the signal on the disk is being read, and changes the frequency of the reference clock depending on the track where this signal is being read. Just let it happen.

By the way, conventionally, a potentiometer having a slider that moves in the radial direction of the disk is provided integrally with the pick-up, and the track where the signal on the disk is being read is detected by the output voltage of this potentiometer. ing. However, this method not only requires a highly accurate potentiometer, but also when the disk expands and contracts in the radial direction, the output voltage of the potentiometer no longer corresponds to the track on the disk, making it difficult to read the signal. There is an inconvenience that the track being tracked cannot be detected accurately.

OBJECTS OF THE INVENTION In view of the above, the present invention enables accurate detection of tracks on which information on a disk is read by a simple means without being affected by expansion and contraction in the radial direction of the disk. The rotation of the disk is controlled so that the upper information reading position moves in the tangential direction of the spiral track at a precise linear velocity.

SUMMARY OF THE INVENTION Generally, when signals are recorded on a disk by forming spiral tracks, track address information whose contents change for each track of an appropriate length is also recorded. Optical disks have also been proposed in which signals can be recorded by the user by irradiating them with a light beam, but even with such disks, it is important to record address information, including track address information, at the time of manufacture. It's normal.

In the present invention, focusing on this point, a track from which information on the disk is being read is detected by extracting track address information from the output of a pickup that reads information from the disk, and this extracted track address information is Calculate and
Based on the calculation output, the frequency of the reference clock that determines the number of rotations of the disk is made to correspond to the track from which information on the disk is being read.

Embodiment FIG. 1 shows an example of the rotation control device of the present invention, in the case of a rotation control device for an optical disk in an optical disk player, in which a disk 10 has a spiral track on which address information including track address information is recorded. are doing. Figure 2 shows an example of the track format. A track of an appropriate length is divided into 20 sectors from sector 0 to sector 19, and each sector consists of an address area followed by a signal data area. , synchronization information SY and address information AD are inserted repeatedly into the address area three times, and the address information AD includes information on the track address (track number) T, sector number SN, etc. following the address mark AM. It is something that

The disk 10 is attached to a shaft 21 of a motor 20 and rotates in one direction. A frequency generator 3 is attached to the shaft 21.
0 is generated, and from this a signal with a frequency proportional to the number of rotations of the disk 10 is obtained. Further, a reference clock generation circuit 40 is provided, which determines the number of revolutions of the disk 10, and provides a reference clock whose frequency is variable. Specifically, the reference clock generation circuit 40 is composed of an oscillation circuit 41 that generates pulses of a constant frequency, and a frequency division circuit 42 that divides the output pulses into 1/N. By changing the ratio N, the frequency of the output reference clock can be changed. The reference clock of the signal obtained from the frequency generator 30 and the output of the reference clock generation circuit 40 is then output to the phase comparator circuit 51 and the servo circuit 5.
2 is supplied to the phase comparator circuit 51 of the motor control circuit 50 consisting of 2 and the phases of the two are compared, and the comparison output is supplied to the motor 20 through the servo circuit 52 to determine the frequency of the signal obtained from the frequency generator 30. The motor 2 is set so that the rotation speed of the disk 10 is in a ratio that is the reciprocal of the number of poles of the frequency generator 30 to the frequency of the reference clock.
0 is controlled.

On the other hand, the pick-up 6 is sent in the radial direction of the disk 10 while irradiating the disk 10 with a light beam.
0 reads from the disk 10 the information recorded on its spiral track. and,
The output of this pickup 60 is the information processing circuit 70.
The information on the track address T mentioned above is separated and extracted. Specifically, the output of the pickup 60 is supplied to a waveform shaping circuit 72 through an amplifier circuit 71 and shaped into pulses, and the pulses are supplied to a phase-locked loop (PLL) 73 to obtain a clock. , synchronization information SY and address mark AM are detected from the output of the waveform shaping circuit 72 using the clock from the phase-locked loop 73, and the demodulation circuit 75 detects the clock from the phase-locked loop 73 from the output of the waveform shaping circuit 72. and the synchronization information SY and address mark AM from the detection circuit 74 are used,
The information on the track address T and signal data are demodulated, and the processing circuit 76 separates the information on the track address T and the reproduced signal from the output of the demodulation circuit 75 using the synchronization information SY and address mark AM from the detection circuit 74. taken out.

The track address information taken out from the information processing circuit 70 is supplied to the arithmetic control circuit 80 where it is computed as described later, and the computed output is sent to the frequency divider circuit 42 of the reference clock generation circuit 40 as a signal that determines the frequency division ratio N. The frequency of the reference clock for determining the number of revolutions of the disk 10 is made to correspond to the current track address, that is, to the track on the disk 10 whose information is being read by the pickup 60.

In order for the information reading position by the pick-up 60 on the disk 10 to move at a constant linear speed in the tangential direction of the spiral track, the disk 1
It is necessary to control the rotation of the disk 10 so that the rotational speed R or the angular velocity at zero varies in inverse proportion to the diameter of the track from which information is being read by the pickup 60. In other words, the rotation period S (=1/R) of the disk 10 needs to change in proportion to the diameter of the track from which the pickup 60 is reading information. Incidentally, the aforementioned track address T is selected to have a linear relationship with the diameter of the track. Therefore, the rotation period S of the disk 10 is the third with respect to the track address T of the track whose information is being read by the pickup 60.
It suffices if it changes according to the characteristics shown in the figure. However, this is the case when the track address T is zero on the innermost track and TO on the outermost track, SI is the rotation period when information is read from the innermost track, and S0 is the outermost track. It is the rotation period when information is read from the , and its characteristics are expressed as S = S0 - SI / T0T + SI ... (1). Here, if the number of poles of the frequency generator 30 is P, the frequency of the signal obtained from the frequency generator 30 is P times the rotation speed R of the disk 10, that is, one period of the signal obtained from the frequency generator 30 is This is 1/P of the rotation period S of the disk 10. Therefore, if the frequency of the pulse output from the oscillation circuit 41 of the reference clock generation circuit 40 is F0, and the frequency of the reference clock output from the frequency dividing circuit 42 is F, then F=P・
The frequency dividing ratio N of the frequency dividing circuit 42 may be changed according to the track address T so that R, that is, 1/F=S/P. Since F=F0/N, that is, N=F0/F, in short, N=F0/F=F0/PS=F0/P(S0−SI/T0T+SI)...(2) .

Specifically, the diameter of the outermost track is twice the diameter of the innermost track, and the rotation speed when information is read from the innermost track is 30 revolutions per second (per minute).
1800), therefore SI = 1/30 second, and the number of revolutions when information is read from the outermost track is 15 per second (per minute
900), so if S0 = 1/15 seconds and P = 32, F0 = 1 MHz = 10 ⁶ Hz, then N = 10 ⁶ /32 {(1/15 - 1/30 )T/T0+1/30}
= ^{10 6 / 32} disk 10
If the format of the track address T is determined, the relationship N=10 ⁵ /3×2 ⁽⁵⁺ⁿ⁾ T+10 ⁵ /3×2 ⁵ (4) can be established. A signal for determining the frequency division ratio N can be easily obtained from the information by only multiplication and addition, and the frequency F of the reference clock can be made to correspond to the track on the disk 10 from which information is being read.

Effects of the Invention As is clear from the above explanation, according to the present invention, by extracting track address information from the output of a pick-up that reads information from a disk, it is possible to eliminate the effects of expansion and contraction in the radial direction of the disk. In addition, by simply multiplying and adding the retrieved track address information, the frequency of the reference clock that determines the number of rotations of the disk can be detected on the disk. The information can be changed depending on the track being read.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an example of a rotation control device of the present invention, FIG. 2 is a diagram showing an example of a disk track format, and FIG. 3 is a diagram showing an example of the characteristics to be obtained. In the figure, 10 is a disk, 20 is a motor, 30 is a frequency generator, 40 is a reference clock generation circuit, and 5
0 is a motor control circuit, 60 is a pickup, 70
8 is an information processing circuit, and 80 is an arithmetic control circuit.

Claims (1)

[Scope of Claims] 1. A motor that rotationally drives a disk having a spiral track on which track address information is recorded, a signal generator that generates a signal having a frequency proportional to the number of rotations of the disk, and the disk. It is assumed that the rotation speed of
A reference clock generation circuit that generates a reference clock whose frequency is variable compares the phase of the signal obtained from the signal generator with the reference clock, and the comparison output obtained thereby determines the rotation speed of the disk. a motor control circuit that controls the motor to maintain a constant ratio to the frequency of the reference clock; a pick-up that reads information including the track address information from the disk; and a pick-up that reads information including the track address information from the disk; an information processing unit for extracting track address information; and an arithmetic output obtained by calculating the track address information extracted by the information processing unit, and information is read from the frequency of the reference clock by the pickup on the disk. A disk rotation control device comprising: an arithmetic control circuit for controlling the reference clock generation circuit in order to correspond to a track;