JPS6132272A - Positioning control system for magnetic head - Google Patents

Abstract

PURPOSE:To shorten an arithmetic period by dividing digital arithmetic processing necessary for servo head positioning into a part which requires high-speed arithmetic and a part which is performed sufficiently by low-speed processing, and putting different computing elements in charge of them. CONSTITUTION:Servo information recorded on a magnetic disk 12 is obtained as an analog position signal 14 through a servo head 9 and a demodulator 10 and the number of times of zero crossing of the position signal 14 is counted by a counter 13 to obtain the number of tracks that the servo head 9 moves over. Further, the position signal is passed through an A/D converter 11 to obtain the relative error from the center of a track as a digital value, and the output of a high-speed digital computing element 16 is inputted to a power amplifier 7 through a D/A converter 6 to drive an actuator 8. A timing computing element 15 performs timing control over the counter 13, A/D converter 11, D/A converter 6, and high-speed digital computing element 16 within one arithmetic period. The obtained error signal is inputted to the power amplifier 7 through the D/A converter 6 to drive the actuator 8, thereby positioning the servo head 9 properly. Consequently, the high-speed, high-precision magnetic head position control is performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of positioning a magnetic head of a magnetic disk device using a digital computing unit, and particularly relates to a method for positioning a magnetic head of a magnetic disk device using a digital computing unit, and particularly for high-speed digital computing that is arranged on the same bus line. The present invention relates to a system that utilizes two digital arithmetic units: a timing generator and a timing arithmetic unit that constitutes a timing generator.

In recent years, magnetic disk devices have become more densely packed with storage capacity.
There is an increasing demand for high-speed processing functions, and in particular, there is a desire for technological development for faster and more reliable positioning control of magnetic heads.

[Conventional technology]

Conventionally, in positioning control of a magnetic head, servo feedback control is used to achieve high precision positioning. That is, a position signal indicating the position of the magnetic head on each track is used as an observation signal in the servo loop, and the error signal (difference between the command signal and observation signal) generated in the feedback control circuit is amplified, and the output is This control drives the actuator to move the magnetic head onto any desired trunk.

In general, the control modes include a seek mode (hereinafter referred to as mode B) in which the servo head is moved from the current track to the target track at high speed, and a tracking mode (hereinafter referred to as mode B) in which the servo head is positioned on the target track with high precision. There are two types (abbreviated as A).

FIG. 5 shows an example of a block diagram of a conventional magnetic head positioning digital control system. In the figure, 9 is a servo head, and 10 is a demodulator, which outputs a position signal of the rad 9 to the servo as an analog value. Reference numeral 11 denotes an A/D converter whose output is input to the command speed generator 2 and the difference section 3. ■ Commands the position of the servo head using an external controller. 4 is a digital filter, 5 is a subtracter, 6 is a D/A converter, 7
is a power amplifier, and 8 is an actuator that drives the servo head.

[Problem that the invention seeks to solve]

As shown in the figure, when attempting to position the servo head 9 with high precision using a digital circuit, the main functions required are the external controller 1.
The input of the target trunk number to the command speed generator 2, the interface function to process the servo head movement start command signal, etc., the observation signal sample function to detect the speed of the servo head in the difference section 3, and the command speed generator 2 Digital filter 4 for digital error generation function of head position and phase compensation of control signal
0 functions, etc., and it is required to process these at high speed.

Looking at the computing power of microprocessors currently available in the world, the time required to execute one machine language instruction (instruction time) is approximately 1 to 10 μS, and the various functions mentioned above can be performed in one machine language instruction. It is extremely difficult to configure a digital signal control system that uses a microprocessor and has a high precision sampling frequency. Also,
Although there are digital processors dedicated to high-speed signal processing (with an instruction time of about 1 ounce), they often have limited processing functions, making them unsuitable.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide a high-speed, highly accurate magnetic head positioning control system in a digital manner by combining a plurality of microprocessors.

[Means to solve the problem]

The present invention provides a digital magnetic head positioning control system that solves the above problems. The means for this is the head position signal of the servo head in the magnetic disk drive and the position from the outside.

In a servo feedback control configuration in which head positioning is performed using an error signal with respect to a command signal, a timing calculator that receives each position signal and controls the operation timing of each device constituting the servo feedback control loop; A magnetic head positioning control method according to the present invention, characterized in that a digital arithmetic unit that calculates the feedback error signal by using a digital arithmetic unit and a converter that converts input and output signals of the digital arithmetic unit are connected on the same bus line. This is achieved by providing

[Effect]

That is, when the present invention achieves the above magnetic head positioning using a digital control system, various digital calculation processes are divided into a part that requires high-speed calculation processing and a part with a timing generation function that requires relatively low-speed processing, and each A high-speed, high-precision magnetic head positioning control system is achieved by having separate appropriate digital computing units take charge of the processing.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment of the hardware configuration of the present invention as a block diagram. In order to make the explanation of the configuration and operation easier to understand, the same corresponding parts are given the same reference numerals throughout all the figures, and their repeated explanation will be omitted.

In FIG. 1, servo information recorded on a magnetic disk 12 is obtained as an analog position signal 14 via a servo head 9 and a demodulator 10. Since the position signal 14 is normally repeatedly demodulated for each track with a certain positive and negative voltage width, the servo head 9 is counted by counting the number of zero crossings with the counter 13.
The number of moving tracks is obtained. Also, the position signal 14 is
By passing the signal through the /D converter 11, the relative error from the track center can be obtained as a digital value.

The two digital arithmetic units that feature the present invention are 15 and 16
16 is in charge of high-speed calculation functions. The output of the high-speed digital arithmetic unit 16 is input to a power amplifier 7 via a D/A converter 6, and drives an actuator 8. Reference numeral 15 denotes an arithmetic unit for timing control, and a general digital arithmetic unit is used to generate a required timing signal. This timing calculator 15 includes a counter 13 and an A/D converter 1 which are other digital processing units within one calculation cycle.
1 has signal lines 17 to 22 for timing control of the D/A converter 6 and the high-speed digital arithmetic unit 16, respectively. The timing calculator 15 also has a plurality of signal lines 23 for interfacing with the external controller 1.

Reference numeral 24 indicates a common path line, and signals are exchanged according to the access timing of each signal line for reading and writing each data necessary for calculation.

FIG. 2 shows an example flowchart of a program required for the timing calculator 15 and the high-speed digital calculator 16 in mode A and mode B. In the figure, the numbered arrows connecting the left and right flowcharts correspond to the control signals vA17 to vA22 in FIG. Since the input/output of these control signals does not involve numerical calculations, it can be sufficiently executed within the calculation period by a general calculation unit constituting the timing calculation unit 15.

The timing calculator 15 always monitors changes in the state values of each of the signal lines 17 to 23 mentioned above within the calculation cycle, and changes in these state values are determined by an input command for the number of target tracks to be moved or from mode A. This corresponds to a mode switching command to mode B.

On the other hand, what is required for high-speed calculation processing is the mode A1 or mode B calculation routine shown in FIG. 2, and it is necessary to calculate an appropriate feedback error signal in each mode and to calculate a digital filter for phase compensation.

The error signal thus obtained is input to the power amplifier 7 via the D/A converter 6, and drives the actuator 8 to appropriately position the servo head 9 attached thereto.

FIG. 3 shows a modification of the hardware configuration of the present invention. When using a servo information recording method in which a digital position signal is obtained by directly counting servo pulses obtained from the servo head 9, a demodulator 10, an A/
Instead of using the D converter 11 and the counter 3, a servo pulse counting circuit 25 shown in FIG. 3 is used. In the figure 26
is a signal line for controlling the operation timing of the servo pulse counting circuit.

In this case, the number of moving trunks of the servo head 9 in the seek mode (mode B) must be determined by the high-speed digital arithmetic unit 16 by looking at the change in the sign of the digital position signal.

FIG. 4 shows a flowchart of a modification using a servo pulse counting circuit. In this case, compared to FIG. 2, only the flow after inputting and outputting each synchronizing signal is different.

〔Effect of the invention〕

As explained in detail above, according to the magnetic head positioning control method of the present invention, the digital calculation processing required for servo head positioning is divided into parts that require high-speed processing and parts where relatively low-speed processing is sufficient. By dividing the processing into separate digital arithmetic units, the calculation cycle can be shortened, and by configuring a high-frequency sample control system, highly accurate servo control can be achieved.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the hardware configuration of the present invention, Fig. 2 is a flowchart of the program required for the timing calculator and high-speed digital calculator in mode A and mode B, and Fig. 3 is the main FIG. 4 is a flowchart corresponding to FIG. 3, and FIG. 5 is a block diagram showing an example of a conventional magnetic head positioning digital control system. In the figure, 1 is an external controller, 6 is a D/A converter, 9 is a servo head, 11 is an A/D converter, 12 is a magnetic disk, 13 is a counter, 14 is a servo head position signal, and 15 is a timing calculator. , 16 is a high-speed digital arithmetic unit, and 24 is a common pass line. Figure 1

Claims (1)

[Claims] In a servo feedback control configuration in which head positioning is performed using an error signal between a head position signal of a servo head in a magnetic disk device and a position command signal from an external source, each device receives each of the position signals and forms a servo feedback control loop. A timing computing unit that controls the operating timing of the digital computing unit, a digital computing unit that calculates the feedback error signal at the operating timing, and a converter that converts the input and output signals of the digital computing unit are connected on the same bus line. A magnetic head positioning control system characterized by: