JPH02162567A - Disk rotation controller - Google Patents

Abstract

PURPOSE:To always set rotating speed at a prescribed value by providing a means to control a voltage, which is impressed to a rotating means, in order to rotate a disk at a fixed linear velocity, and controlling the gain of the rotation control means in correspondence to the moving direction of a reading means. CONSTITUTION:When a pickup 3 is largely moved, since a rotary servo circuit 5 outputs an acceleration voltage in order to accelerate a motor 2. At such a time, a moving direction detecting circuit detects the moving direction of the pickup 3 and when the pickup 3 is moved, the signal of a high level is impressed to a resistor 16 of a buffer amplifier 6, which is constituted in feedback resistors 11 and 12, and the base of a transistor 14. Thus, when the pickup 3 is moved in a central direction, a larger deceleration voltage is applied to the motor 2 rather than a case that this pickup moves in an outer circumferential direction. Thus, since the gain is made small when the pickup moves in the outer circumferential direction, the small deceleration voltage is impressed to the motor together with a back electromotive voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a disk rotation control device that rotates a disk at a constant linear velocity.

(B) Conventional Technology When recording information on an optical disk or the like, it is advantageous to drive the disk to rotate at a constant linear velocity because it is possible to achieve a higher recording density than to drive the disk to rotate at a constant angular velocity.

Therefore, as a method of rotationally driving a disk at a constant linear velocity, as shown in Japanese Patent Laid-Open No. 19767/1983, the distance from the center of the disk of a pickup for recording or reproducing to the disk is detected, and the distance is determined by detecting the distance from the center of the disk. A voltage corresponding to the voltage is applied to the disk rotation drive motor.

(C) Problems to be Solved by the Invention Incidentally, since the motor that rotates the disk changes its rotational speed depending on the position of the pickup, a back electromotive force is generated. If the pickup position does not change drastically, such as when recording or playing back information on a disc,
Since the amount of change in the rotational speed of the motor is small, it is not affected by the above-mentioned reverse electromotive force.

However, when the position of the pickup changes significantly due to high-speed search, etc., the rotational speed of the motor must also change significantly, which causes a sudden change in the voltage applied to the motor, which reduces the back electromotive force mentioned above. It will be greatly affected.

For example, the driving voltage of the motor is Fb, the back electromotive force generated by the rotation of the motor is Ec, and the winding resistance of the motor is Ra.
Then, the motor current 1a becomes (Eb-Ec)/Ra. Here, since the direction of rotation of the disk is unidirectional even though the number of rotations changes, the back electromotive force always acts in the opposite direction to the direction of rotation of the disk.

Therefore, when the motor decelerates (when the pickup moves toward the center of the disk), the back electromotive force acts as a brake to help decelerate the motor, and the motor current decreases (-
l IEb l −I Ec l )/Ra. On the other hand, when the motor accelerates (when the pickup moves toward the outer circumference of the disk), the back electromotive force moves in the direction that accelerates the motor, and the motor current becomes (11Ebl - l Ecl
)/Ra.

From the above, when the pickup moves between points A and B, if the moving direction is different, even if the same driving voltage IEbl is applied, the magnitude of the motor current will be the same as the back electromotive force. It will be different depending on the influence. Therefore, the time required to fix the motor to a predetermined rotation speed becomes unstable, making it impossible to perform a stable high-speed search.

(d) Means for Solving the Problems The disk rotation control device of the present invention includes a disk on which a signal is recorded, a reading means that moves along the radial direction of the disk and reads the recorded signal, and a device that reads the recorded signal. A rotation means for rotating the disk, and a rotation control means for controlling a voltage applied to the rotation means in order to rotate the disk at a constant linear velocity, the gain of the rotation control means being adjusted according to the moving direction of the reading means. It is characterized by control.

(E) Function According to the present invention, when the reading means moves toward the center of the disk, a large acceleration voltage is applied to the motor by increasing the gain of the rotation control means;
When the reading means moves toward the outer circumference of the disk, the gain of the rotation control means is reduced so that a small deceleration voltage is applied to the motor along with a back electromotive force.

(v) Embodiment The figure is a block diagram showing an embodiment of the present invention. A disk (1) on which signals have been recorded is rotated by a motor (2) at a constant linear velocity. In this state, a signal is read from the disk (1) by the pickup (3), and this signal is demodulated by the signal reproducing circuit (4). A signal reproducing circuit (4) detects a frame synchronization signal from the demodulated signal and supplies it to a rotation servo circuit (5).

On the other hand, the reference signal generator (6) generates a reference signal according to the position of the pickup (3), and the rotation servo circuit (
5) compares the reference signal and the frame synchronization signal, and if the frame synchronization signal matches the reference signal, P L L (Ph
As Locked Loop) is generated, an error voltage is generated so that the loop is locked.

Then, this error voltage is applied to the motor drive circuit (7) via the resistor (lO) and the buffer amplifier (6), and an appropriate voltage is applied from the motor drive circuit (7) to the motor (2).
given to.

By the above operation, the disk (1) is moved to the pickup (3).
), the rotation is controlled at a constant linear velocity.

By the way, when the pickup (3) moves largely towards the center (or towards the outer periphery) due to a high-speed search for recording signals, etc., the rotation servo circuit (5) accelerates (or decelerates) the motor (2) when the movement is completed. ) Outputs the acceleration voltage (or deceleration voltage) for

At this time, the moving direction detection circuit (8) detects the pickup (3).
When the pickup (3) moves toward the center (or toward the outer periphery), the feedback resistance (11
) (12), a resistor (13) and a transistor (12) are connected to the feedback loop of the buffer amplifier (6).
A high level (or low level) signal is applied to the base of the transistor (14) on line 14).

Therefore, when the pickup (3) moves toward the outer circumference, the resistance values of the resistors (10), (11), and (12) are set to R,
R.

and R1, the gain of the buffer amplifier (6) is (
Rt”Rs)/Rs.On the other hand, the pickup (
3) moves toward the center, and if the resistance value of the resistor (13) is R4, the gain of the buffer amplifier (6) is (R
t”Rs◆R1R, /R, )/R, As a result, when the pickup (3) moves toward the center, a larger deceleration voltage is applied to the motor (2) than when it moves toward the outer circumference. Specifically, the pickup (3
) moves toward the center, the resistance value R1 of each resistor (10) (11) (12) and (13) is adjusted so that the voltage Eb when moving toward the outer circumference becomes Eb+2Ec. , R1, R1 and R4 are determined and the gains are adjusted.

(G) Effects of the Invention According to the present invention, since the gain of the motor rotation control means is controlled according to the moving direction of the reading means (pickup), the motor is always activated at a constant time regardless of the moving direction of the reading means. The number of rotations of the disk can be set to a predetermined value, and stable disk rotation control can be performed.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. (1)...Disk, (2)...Motor, (3)...
... Pickup, (5) ... Rotating servo circuit, (6
)...Buffer amplifier, (7)...Motor drive circuit.

Claims (1)

[Claims] (1) A disk on which a signal is recorded, a reading means that moves along the radial direction of the disk and reads the recorded signal, a rotating means that rotates the disk, and a rotating means that rotates the disk at a constant linear velocity. 1. A disk rotation control device comprising: a rotation control means for controlling a voltage applied to the rotation means for the purpose of the present invention, and controlling a gain of the rotation control means according to a moving direction of the reading means.