JP2733392B2 - Head feed control device for disk drive device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive for recording and reproducing information on an optical disk or a magneto-optical disk, and more particularly, to moving a head in a traverse direction with respect to a track on the disk. The present invention relates to a head feed control device of a disk drive device to be driven.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional typical configuration of a head feed control device in an optical disk drive. In FIG. 1, reference numeral 1 denotes an optical disk which is set on a rotating base 2 and rotated, and 3 denotes an optical head which reads information on the disk 1. The head 3 is moved in the traverse direction with respect to the track of the disk 1 by a linear motor (not shown). Reference numeral 4 denotes a drive unit of the linear motor.

The read signal output from the head 3 is A / D
The data is digitized by the converter 5 and input to the head position / speed detector 6. The detector 6 is a circuit for detecting the position and speed of the head 3 when the head 3 is traversed. The detector 6 samples a read signal of a control information pit recorded on the disk 1 from the head output, and controls the signal. The position of the head 3 and the traverse speed are calculated from the information.

The position signal from the detector 6 and the target position signal from the system controller 7 are input to a subtractor 8,
The position deviation is obtained. A target speed corresponding to the position deviation is set in advance in the target speed memory 9, and upon receiving the position deviation signal output from the subtracter 8, a target speed signal corresponding to the position deviation is output. The target speed signal and the speed signal from the detector 6 are input to a subtractor 10 to determine a speed deviation.

The speed deviation signal from the subtractor 10 passes through a phase compensation circuit 11 for increasing the phase margin at the gain intersection of the servo characteristics to stabilize the servo, and then the D / D signal.
The signal is converted into an analog signal by the A converter 12 and input to the motor drive unit 4. The motor drive unit 4 drives the traverse feed linear motor so that the input speed deviation signal becomes zero, and moves the optical head 3 to the target position according to the target speed.

FIG. 5 shows the operation characteristics of this control system. When a target position and a traverse command are given while the head 3 is stopped, a large target speed corresponding to a large positional deviation is first output from the memory 9, and the actual speed of the head 3 rapidly increases from zero. As the head 3 approaches the target position, the target speed decreases, and when the actual speed becomes substantially equal to the target speed, the actual speed decreases following the target speed and stops at the target position.

[0007]

In the above control system, as shown in FIG. 5, the actual speed of the head 3 decreases while following the target speed, as shown in FIG. There is a time Δt (called a delay time) until the actual speeds match, and therefore a speed deviation ΔV exists. Although the delay time Δt and the speed deviation ΔV cannot be made completely zero, high-precision servo control can be realized by making them as small as possible.

In recent electronic technology, this type of control device is usually realized by a digital circuit. To reduce the delay time Δt and the speed deviation ΔV to increase the control accuracy, it is necessary to use digital processing. The sampling frequency and control cycle must be shortened by increasing the clock frequency.
However, there is a problem that such a high-speed circuit device becomes very expensive. In terms of the price of the apparatus, it is desirable to configure the control system by software processing using an inexpensive microcomputer. However, it is difficult to increase the sampling period and the control period, and high-performance servo control cannot be realized.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a disk drive apparatus capable of realizing higher-precision servo control even with an inexpensive digital control system that is not so fast. An object of the present invention is to provide a head feed control device.

[0010]

A head feed control device according to the present invention comprises a feed motor for moving a head in a track traverse direction, a means for sampling and detecting the position and speed of the head when the head is fed, Means for obtaining a deviation from a target position, means for outputting a target speed according to the position deviation, and delay linear correction means for linearly correcting the delay of the feed motor according to a control cycle with respect to the target speed; Means for calculating a deviation between the corrected target speed and the detected speed, and means for driving the feed motor in accordance with the speed deviation.

[0011]

The target speed is determined in accordance with the deviation between the detected position of the head and the target position. The linear delay correcting means operates on the target speed, taking into account the delay time caused by the control cycle. Linear correction is performed, and motor control is executed according to the corrected target speed.

[0012]

FIG. 1 shows a schematic configuration of a head feed control device according to an embodiment of the present invention. The overall basic configuration of the control system is the same as that of the conventional device of FIG. 4, and the same components are denoted by the same reference numerals. 1 is different from the conventional one in a configuration in which a target speed signal output from a target speed memory 9 is input to a subtractor 11 via a delay linearity correction circuit 13.

FIG. 2 shows a configuration example of the correction circuit 13. This correction circuit 13 subtracts a register 13a for delaying the target speed signal from the memory 9 by one sample and a difference v (a change in the target speed) between the undelayed target speed signal and the delayed target speed signal. 13b, a multiplier 13c for multiplying the target speed change v by an appropriate constant G, and an adder 13 for adding the multiplied output v × G to the undelayed target speed signal.
d. FIG. 3 shows the operation of the correction circuit 13. When the target speed V2 is output from the memory 9 at the time point t2, the register 13a outputs the target speed V1 one sample before.
Is output from the subtractor 13b, and the change v = V2-V1
Is output from the multiplier 13, and the corrected target speed (V2 + v × G) is output from the adder 13d. The difference between the corrected target speed signal and the speed signal from the detector is calculated by the subtracter 10, and the speed difference is supplied to the motor drive unit 4 via the phase compensation circuit 11 and the D / A converter 12. Then, the feed motor of the head 3 is servo-controlled.

[0014]

As described above in detail, in the head feed control device of the present invention, the response delay of the actual speed of the motor with respect to the target speed determined according to the deviation between the target position and the detected position of the head. Is linearly corrected in accordance with the control cycle, and the motor is controlled in accordance with the corrected target speed. Therefore, even if the sampling cycle and the control cycle of the digital control system are not so small, the delay time becomes feedforward by the above-described correction processing. Corrected, the actual speed deviation can be made very small. That is, high-precision head feed control can be realized by a digital control circuit which is not so fast and therefore inexpensive.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a head feed control device according to an embodiment of the present invention;

FIG. 2 is a block diagram of a delay linearity correction circuit in the above device.

FIG. 3 is a diagram illustrating the operation of the correction circuit according to the first embodiment;

FIG. 4 is a block diagram of a conventional head feed control device.

FIG. 5 is an operation explanatory diagram showing a problem of the conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 3 Optical head 13 Delay linearity correction circuit 13b Subtractor 13c Multiplier 13d Adder

Claims (1)

(57) [Claims] 1. A feed motor for moving a head in a track traverse direction, a means for sampling and detecting a position and a speed of the head at the time of head feed, a means for obtaining a deviation between the detected position and a target position, and a positional deviation thereof Means for outputting a target speed according to the above, delay linear correction means for linearly correcting the delay of the feed motor according to the control cycle with respect to the target speed, and the corrected target speed and the detected speed. And a means for driving the feed motor in accordance with the speed deviation.