JPH02246063A - Head positioning control circuit - Google Patents

Abstract

PURPOSE:To improve head positioning accuracy by adding a signal to suppress disturbance due to the eccentricity of a disk on a position feedback loop system as a feedforward signal. CONSTITUTION:A switch SW2 is turned off and a switch SW3 is turned on when the phase of a sine wave from a sine wave generator 25 is decided by a sine wave phase adjusting circuit 23. At this time, a switch SW1 remains at an ON-state, and at such state, the gain of the generator 25 is decided so that the output of a peak value detection circuit 22 can be minimized similarly by a sine wave gain control circuit 24. When the gain of the sine wave generated once at the generator 25 is decided by the adjusting circuit 23, the gain remains unchanged until it is changed by the adjusting circuit 23 next. In other words, the optimum phase and gain of the feedforward signal in which the head positioning accuracy goes to the minimum level is decided, and hereafter, all the switches SW1-SW3 are turned off, and the feedforward signal having decided phase and gain is added on the system. In such a way, the head positioning accuracy can be improved.

Description

[Detailed Description of the Invention] (Summary) This invention relates to a head positioning control circuit that performs disturbance suppression control using feedforward in a head positioning control system of a magnetic disk device. , the purpose of improving the positioning accuracy of the control bed is to feed back the position signal reproduced by the control head from the magnetic disk to create a position error signal with respect to the target position signal.
In the head positioning control circuit that inputs this position error signal to the actuator to control the control head on-trunk, a sine wave generator generates a sine wave with the same fundamental frequency as the rotation speed of the spindle motor that rotates the magnetic disk or its harmonics. a phase adjustment circuit that adjusts the phase of the sine wave generation circuit using the position error signal, and a gain adjustment circuit that adjusts the gain of the sine wave generation circuit using the position error signal, and the phase and gain are adjusted. A sine wave is configured to be added to the position feedback loop system as a feedforward signal.

[Industrial application field]

The present invention relates to a head positioning control circuit, and more particularly to a head positioning control circuit that performs disturbance suppression control using feedforward in a head positioning control system of a magnetic disk drive.

In recent years, with the development of computer technology, magnetic disk drives have been increasingly used for recording and reproducing programs and data. As the amount of information to be recorded and reproduced increases, magnetic disk drives are required to have higher density (narrower track width). A magnetic disk drive generally has a data head that writes and outputs data, and a control head that determines the position of this data head. Positioning by the control head includes (1) moving from the currently accessed track to the target track control for moving the data head;
(2) On-trunk control that keeps the data head on the track currently being accessed. As the density of magnetic disk drives continues to increase, there is a demand for more precise head positioning accuracy during on-track.

[Conventional technology]

FIG. 5 shows the configuration of a head positioning control circuit of a conventional magnetic disk device. In the figure, 51 is a control head, 52 is a magnetic disk rotated by a spindle motor 53, and the control head 51 is attached to an actuator 58 driven by a voice coil motor 57. The servo signal written on the magnetic disk 52 is reproduced by the control head 51, input to the position signal demodulation circuit 54, demodulated, fed back as a position signal, and subtracted from the target position signal to create a position error signal. Here, the target position signal is an instruction signal from a higher-level control device such as a personal computer.

Then, the position error signal is input to the phase compensation circuit 55 to become a phase compensation signal, which is amplified by the amplifier, rotates the voice coil motor 57, and performs position correction (tracking) of the control head 51 via the actuator 58. .

[Problem to be solved by the invention]

However, in conventional head positioning control systems in which a position feedback loop is formed from servo signals written on the disk surface to position the control head, the frequency band of position errors that can be reduced by the control system is basically limited to It cannot be raised above the resonance frequency (usually about several K11z) of the moving parts (control head 51, actuator 58),
Sufficient suppression was not possible depending on the magnitude of the disturbance caused by the eccentricity of the magnetic disk (around 60 KHz), which is equal to the spindle rotational speed in the low frequency range.

Therefore, the inventor of the present invention discovered that the factor that deteriorates the head positioning accuracy when the control head is on-track is the existence of a disturbance synchronized with the basic spindle rotation speed (hereinafter referred to as spindle eccentric disturbance) caused by the mechanical eccentricity of the magnetic disk. Focusing on a certain fact, this spindle eccentric disturbance is synchronized with the spindle rotation, and when the position error signal is observed, it appears as a sine wave synchronized with the fundamental rotational frequency of the disk as shown in Figure 6. This invention has been made. That is, an object of the present invention is to reduce spindle eccentric disturbance in a head positioning control circuit and improve positioning accuracy of a control head.

[Means to solve problems]

The configuration of a head positioning control circuit according to the present invention that achieves the above object is shown in FIG. The present invention provides head positioning in which a position signal reproduced by a control head 1 from a magnetic disk is fed back to create a position error signal with respect to a target position signal, and this position error signal is input to an actuator 2 to control the control head on-track. In the control circuit, a sine wave generating circuit 4 generates a sine wave or harmonics thereof having the same fundamental frequency as the rotation speed of the spindle motor 3 that rotates the magnetic disk, and the phase of the sine wave generating circuit 4 is adjusted by the position error signal. and a gain adjustment circuit 6 that adjusts the gain of the sine wave generation circuit 4 using the position error signal, and the sine wave whose phase and gain has been adjusted is used as a feedforward signal to the position feedback loop system. It is characterized by adding

[For production]

According to the head positioning fIII'a circuit of the present invention, the phase adjustment circuit 5 generates a sine wave so that the peak-to-peak peak value (P-P value) of the position error signal obtained during one disk rotation period is minimized. The phase of the generator 4 is determined, and then the phase of the sine wave generator 4 is determined by the gain adjustment circuit 6 so that the peak value (P-P value) of the position error signal is minimized, and the optimum phase and gain are determined. The provided sine wave is added to the feedbank system as a feedforward signal.

〔Example〕

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings, but the same parts as those of the conventional head positioning control circuit will be given the same reference numerals and the explanation thereof will be omitted.

FIG. 2 shows the configuration of an embodiment of the head positioning control circuit of the present invention, in which numeral 51 represents a control head, 52 represents a magnetic disk, 53 represents a spindle motor, position signal demodulation circuit 54, Phase compensation circuit 55, amplifier 56,
A feedback loop system composed of a voice coil motor 57 and an actuator 58 is the same as a conventional head positioning control circuit. In addition to the feedback loop system as described above, this embodiment is provided with a feedforward system that generates a sine wave from the branched position error signal and superimposes this sine wave on the output of the phase compensation circuit 55. This feed forward system uses switch SW
I.

Sample and hold circuit 21. A peak value detection circuit 22 that detects the peak value of P-P. Switch SW2. SW3. Sine wave phase adjustment circuit 23. Sine wave gain adjustment circuit 24. It is composed of a sine wave generator 25 and a spindle rotation synchronization signal generator 27. The sine wave phase adjustment circuit 23 includes switches S&
42 is on, the spindle rotation synchronization signal generator 27
The phase of the sine wave generator 25 is arbitrarily set based on the same signal obtained from the spindle rotation synchronization signal generator 27 when the switch SW3 is on. The gain of the sine wave generator 25 is arbitrarily set based on . The sine wave generated by the sine wave generator 25 is added as a feedforward signal to a feedback loop system subsequent to the phase compensation circuit 55, and inputted to the amplifier 56.

Next, the operation of the head positioning control circuit configured as above will be explained.

First, when the power of the magnetic disk device is turned on, the switch SWI and the switch 2 are turned on. Then, the position error signal is sampled and held by the sample and hold circuit 21, and from that value, the peak value detection circuit 22 calculates P-P of the position error signal obtained during the disk rotation period.
The value is determined and sent to the sine wave phase adjustment circuit 23. Then, the phase of the input sine wave is changed by the sine wave phase adjustment circuit 23, and the phase at which the output (P-P value) of the peak value detection circuit 22 is the minimum is determined. Once the sine wave phase adjustment circuit 23 determines the phase of the sine wave generated by the 4-sine wave generator 25, this phase does not change until the sine wave phase adjustment circuit 23 changes the phase next time. In this state, switch 3 is off.

When the phase of the sine wave from the sine wave generator 25 is determined by the sine wave phase adjustment circuit 23, the switch SW2 is turned off and the switch SW3 is turned on instead.

At this time, switch 1 remains on. In this state, the sine wave gain adjustment circuit 24 also causes the peak value detection circuit 2 to
The gain of the sine wave generator 25 is determined so as to minimize the output CF'-P value of 2). Sine wave gain adjustment circuit 23
Once the gain of the sine wave generated by the sine wave generator 25 is determined, this gain is then determined by the sine wave gain adjustment circuit 23.
It does not change until the gain is changed by . This means that the P-P value of the position error signal, that is, the optimal phase and gain of the feedforward signal (sine wave) that minimizes the positioning accuracy has been determined. - degree After these values are determined, switches SWI, SW2 . SW3 is all turned off and a feedforward signal with a determined phase and gain is added to the system.

FIG. 3 shows the configuration of another embodiment of the present invention,
Switch S-1 and sample hold circuit 21 in FIG. A peak value detection circuit 22 that detects the peak value of P-P.
Switch SW2. SW3. Sine wave phase adjustment circuit 23.
Sine wave gain adjustment circuit 24. A sine wave generator 25 and a spindle rotation synchronization signal generator 27 are configured by an A/D converter 31, a microcomputer 32, a memory 33, and a D/A converter 34.The 0 position error signal is A/D converted. A microcomputer 32 calculates their P-P values. Also,
The fundamental sine wave is stored in the memory 33 as a table, and the feedforward signal is output through the D/A converter 34 at regular time intervals after the microcomputer 32 determines the required phase and gain.

In the head positioning control circuit of the embodiment described above, disturbance suppression control is performed limited to the fundamental frequency of the spindle rotation speed, but it also applies to harmonics of the fundamental frequency such as the second harmonic and the third harmonic. If feedforward signals (sine waves) corresponding to each are determined after similar processing and added to the feedback system, -layer spindle eccentric disturbance can be reduced.

FIG. 4 shows an embodiment of a head positioning control circuit that also corrects harmonics of the fundamental frequency. This embodiment differs from the embodiment shown in FIG. 2 in that, in addition to the sine wave generator 25, a harmonic generator 26 is provided after the sine wave phase adjustment circuit 23 and the sine wave gain adjustment circuit 24. be. The sine wave generator 25 and harmonic generator 26 are operated by a changeover switch 4. Each sine wave phase adjustment circuit 23 via SW5
and the sine wave gain adjustment circuit 24, and the harmonic phase and gain of the harmonic generator 26 are adjusted in the same way as the fundamental frequency phase and gain of the sine wave generator 25 are adjusted by the changeover switch SW4.

This is done by switching SW5.

〔Effect of the invention〕

As explained above, according to the present invention, in a head positioning control system of a magnetic disk drive, a signal for suppressing disturbance caused by eccentricity of the disk is added to the position feedback loop system as a feedforward signal, thereby controlling the magnetic disk drive. It is possible to suppress disturbances caused by disk eccentricity of the device, and there is an effect that head positioning accuracy is improved.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the head positioning control circuit of the present invention, FIG. 2 is a configuration diagram of one embodiment of the head positioning control circuit of the present invention, and FIG. 3 is another embodiment of the head positioning control circuit of the present invention. FIG. 4 is a block diagram of an embodiment of the head positioning control circuit of the present invention, FIG. 5 is a block diagram of a conventional head positioning control circuit, and FIG. 6 is a block diagram of a conventional head positioning control circuit. FIG. 3 is a diagram illustrating dependent disturbances. DESCRIPTION OF SYMBOLS 1... Control head, 2... Actuator, 3... Spindle motor, 4... Sine wave generator 5... Phase control circuit, 6... Gain adjustment circuit.

Claims (1)

[Claims] 1. A position signal reproduced by the control head (1) from the magnetic disk is fed back to create a position error signal with respect to the target position signal, and this position error signal is input to the actuator (2) for control. A head positioning control circuit for on-track control of the head includes: a sine wave generation circuit (4) that generates a sine wave or harmonics thereof having the same fundamental frequency as the rotation speed of a spindle motor (3) that rotates a magnetic disk; A phase adjustment circuit (5) that adjusts the phase of the sine wave generation circuit (4) using the error signal, and a gain adjustment circuit (6) that adjusts the gain of the sine wave generation circuit (4) using the position error signal, A head positioning control circuit characterized in that a sine wave whose phase and gain have been adjusted is added to a position feedback loop system as a feedforward signal. 2. The head positioning control circuit according to claim 1, wherein the phase adjustment circuit (5) and the gain adjustment circuit (6) adjust the optimum phase and gain of the feedforward signal.
A head positioning control circuit characterized in that a head positioning control circuit sequentially determines a peak value of a positional error of a feedback system to be minimized.