JPH02240885A - Head positioning circuit for magnetic disk device - Google Patents

Abstract

PURPOSE:To excellently minimize the excessive response by providing a control means controlling the operation of an integrator and selecting the integration start timing so as to be optimum to a seek condition. CONSTITUTION:A position information signal is demodulated into a position signal by a position signal demodulation circuit 1 during seek operation and differentiated by an electronic tachometer 2 and outputted as the actual measurement speed signal of a servo head. The switching control of a mode switching circuit 6 is implemented by a mode switching control signal generating circuit 11 during seeking and the mode is switched to a position control mode corresponding to the output of a difference counter 13. In this case, an integrator control circuit 12 enables an integrator 9 based on a ROM 22 storing an integrator ON timing information optimum to the seek condition. The integrator 9 applies integration element compensation and proportional element compensation being PID compensation to minimize quickly the excessive response.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of the Invention The present invention relates to a head positioning circuit for a magnetic disk drive, and more particularly to a head positioning control system during a seek operation.

In a magnetic disk drive, the magnetic head is controlled to move from the current position to the target track position in response to a seek operation start command, but in this case, the head is moved in a speed control mode until it approaches the target track position. After that, it is controlled by the position control mode.

In this position control mode, an integrator is used that integrates a position signal to produce a servo signal in order to quickly reduce the transient response by performing integral element compensation and proportional element compensation of PID compensation.

Conventionally, the time from when the speed control mode is switched to the position control mode until the integrator starts operating is designed to be always constant.

However, due to differences in head seek start position conditions, such as outer circumference side, inner circumference side, forward seek, reverse seek, seek length, etc., the effects of external forces on the head differ, resulting in different transient responses of the movement control loop. do. Therefore, the conventional method in which the integrator starts operating after a certain period of time after the control mode is switched has the disadvantage that it may not work toward converging the transient response.

Therefore, the present invention has been made to solve the drawbacks of the prior art, and its object is to provide a magnetic disk that can converge the transient response well under any seek start conditions. An object of the present invention is to provide a head positioning circuit for an apparatus.

According to the present invention, there is provided means for controlling the movement of the head from the current position of the head to the vicinity of the target track position in a speed control mode in response to a seek start command; a head positioning circuit for a magnetic disk device, comprising means for integrating the head position signal by an integrator and controlling the movement of the head in a position control mode using the integrated output when the position signal of the head is reached. storage means that stores in advance the operation start timing of the integrator after switching from the speed control mode to the position control mode according to the difference between the current position of the head at the time of the seek start command and the target track position; There is obtained a head positioning circuit for a magnetic disk device characterized in that it includes a control means for reading the operation start timing of the integrator from the storage means in accordance with the difference and controlling the operation start of the integrator.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and is an example using a closed loop positioning control system. The head positioning operation has two modes, a speed control mode and a position control mode, and during a seek operation, it is controlled by a control loop based on the speed control mode, and during a track follow operation, it is controlled by a control loop based on the position control mode.

In FIG. 1, during a seek operation, a position information signal read by a servo head (not shown) is demodulated into a position signal by a position signal demodulation circuit 1. This position signal is differentiated by the electronic tachometer 2 and output as an actual speed signal indicating the actual speed of the servo head.

Further, a predetermined target speed is written in the read-only memory (ROM) 3 according to the number of remaining tracks from the current track position of the servo head to the target track position. The corresponding target speed using the output remaining track number signal as input is read out as a digital speed reference signal. This digital speed reference signal is output as an analog speed reference signal by a D/A (digital/analog) converter 4.

The measured speed signal from the electronic tachometer 2 and the speed reference signal from the D/A converter 4 are generated by the speed error signal generation circuit 5.
and is output as a speed mode drive signal according to the difference between the two.

During the seek operation, the mode switching circuit 6 is controlled to selectively supply the speed mode drive signal to the power amplifier 7, and after the power amplifier 7 amplifies the current, the drive current is transferred to the voice coil motor 8. supplied to As a result, the speed of the servo head is controlled toward the target track.

During track following operation, closed-loop control of PID compensation is performed, and the position information output from the servo head is demodulated by the position signal demodulation circuit 1 and inputted to the integrator 9 as a position signal. It looks like this. This integrator 9 has a function of performing integral element compensation and proportional element compensation of PID compensation, and quickly converging a transient response.

The integral output is input to the position signal summing amplifier 10, where it is added to the actually measured velocity signal to perform differential element compensation for PID compensation, and is output as a position mode drive signal.

During the track follow operation, the mode switching circuit 6 selects this position mode drive signal and supplies it to the power amplifier 7.Therefore, the power amplifier 7 amplifies the current and inputs it to the voice coil motor 8 as a drive current, and the servo head will be held on the target track.

Switching control of the mode switching circuit 6 is performed by a mode switching control signal generation circuit 11, and when the output of the difference counter 13 becomes "0", the speed control mode is switched to the position control mode. There is. The integrator 9 is enabled after a certain period of time has elapsed from this switching timing, but in the conventional system, the integrator 9 is always enabled after a certain period of time has elapsed. Therefore, the drawbacks mentioned in the prior art section arise.

Therefore, in the present invention, an integrator control circuit 12 is provided to change the timing at which the integrator 9 is enabled depending on the situation. FIG. 2 shows a specific example of the integrator 9 and its control circuit 12.

The integrator 9 consists of an operational amplifier 91, an input resistor 92, a feedback resistor 93, and a feedback capacitor 94.
A switch 95 that turns on and off both ends of this capacitor 94
is provided. An integrator control circuit 12 for controlling this switch 95 includes a microcomputer 21 and a ROM 22.

The microcomputer 21 inputs the target track signal during seek and the head position signal at the start of seek, and determines seek conditions such as seek length, outer circumference side, inner circumference side, forward direction seek, reverse direction seek, etc. from the relationship between both signals. do.

The ROM 22 stores in advance optimal integrator on-timing information corresponding to each of these seek conditions. Based on the seek condition determination result from the microcomputer 21, integrator on timing information corresponding to this condition is read from the ROM 22, and the switch 95 is controlled to be turned on based on this information.

Therefore, the time from when the speed control mode is switched to the position control mode until the integrator 9 is enabled is optimally selected depending on the seek condition, and the low-frequency gain of the control loop is By being lifted by 9, the stiffness becomes large and the transient response can be quickly converged.

As described above, according to the present invention, the integral operation start timing can be selected to be optimal for the seek conditions, so that the transient response after switching the position control mode can always be quickly converged. This has the effect of allowing highly reliable magnetic disk head positioning.

[Brief explanation of drawings]

FIG. 1 is a system block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing a specific example of some of the blocks in FIG. 1. Explanation of symbols of main parts 5...Speed error signal generation circuit 6...Mode switching circuit 9...Integrator 12...Integrator control circuit 21. ...Microcomputer 22...ROM

Claims (1)

[Claims] (1) means for controlling the movement of the head in a speed control mode from the current position of the head to the vicinity of the target track position in response to a seek start command; A head positioning circuit for a magnetic disk drive, comprising means for integrating a position signal by an integrator and using the integrated output to control the movement of the head in a position control mode, the circuit changing from the speed control mode to the position control mode. A storage means that stores in advance the operation start timing of the integrator after switching to the integrator according to the difference between the current position of the head at the time of the seek start command and the target track position, 1. A head positioning circuit for a magnetic disk drive, comprising: control means for reading an operation start timing of the integrator from the storage means and controlling the start of operation of the integrator.