JPS62257683A - Magnetic storage device - Google Patents

Abstract

PURPOSE:To improve the accuracy of head positioning and to attain a high- density track pitch by using a means for detecting a positioning error due to the hysteresis characteristic of a head moving mechanism to detect the positioning error at each start thereby changing the current ratio flowing to an exciting phase of a motor. CONSTITUTION:Whether the access direction is toward the outer circumference of inner circumference is judged by an access instruction and when the direction is from the inner to the outer circumferential direction, a deviation by a positioning error 93 exists. In order to correct it, a correction Nad obtained by a correction detecting means is read from a RAM, a motor phase A current setting value is changed by the value Nad, the current flowing to the motor is changed to bring the head to the position of the outer circumferential position 95 thereby eliminating the positioning error due to the hysteresis characteristic. When the access goes from the outer to the inner circumference, no correction is required and the motor is excited without correction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application tf] The present invention relates to head positioning error correction means for a magnetic storage device.

[Conventional technology] A perspective view of a conventional a-air storage device is shown in FIG.

The head drive motor (step motor) (21) is excited and the motor shaft is rotated by switching the excitation phase.
A carriage (22) to which a magnetic head (22) used for recording and reproduction is fixed using a mechanism that converts rotational motion into linear motion.
23) Move.

Also, the excitation phase switching is stopped and the head is positioned at a predetermined position.

In this head moving mechanism, the positioning position has a hysteresis characteristic due to the rotational direction of the stepping motor (history of the rotational direction of the motor) before it stops at the stop position, causing an error in the positioning position.

This is caused by the hysteresis characteristics of the material constituting the magnetic circuit of the motor and the frictional force of the head moving mechanism, and its occurrence is unavoidable. FIG. 3 shows an example of the results of measuring the hysteresis of the carriage.

recent years,? With the increase in the capacity of a% storage devices, efforts have been made to reduce hysteresis characteristics and head positioning errors.

A first method is to access the final position of the head from only one direction.

As shown in FIG. 4, when accessing from the (n-1) I-rack direction, the track is accessed one track ahead of the target track, and then the direction is changed and the track is positioned at the target track.

A second method is to slightly change the balance of the phase current of the excitation phase of the stepping motor at the final position depending on the direction in which the head accesses, thereby correcting errors due to hysteresis.

FIG. 155 shows an example of a method for changing phase currents. This is a motor excitation circuit for unipolar driving of a four-phase motor. Transistors (51 to (54))
Depending on N and OFF, it is determined whether or not current should flow through the motor coils (63) to (66). In addition, current is transferred to resistors (59) to (62) by transistors (55) to (58).
) or bypass it to a transistor to adjust the current flowing through the coil. The switching sequence of transistors (51) to (54) and transistors (55) to (58) when accessing the head from a certain direction is shown in the sixth column.
At this time, all transistors (55) to (58) are OFF, as shown in Figure A, and the current flows through the resistor coil. Figure 6 shows the switching sequence of the transistors when accessing the head from the opposite direction. Depending on whether the transistors (55) to (58) are turned on, current passes through the transistors. ! - A larger current flows through the coil where the transistor is turned on than the coil where the transistor is turned off. From this fourth point, it is possible to play a game in which the static position of the motor's rotor (head static position) moves slightly compared to when the current is uniformly flowing through the coil.This movement can be made equal to the error caused by the hysteresis characteristic. Then, the current ratio is set (resistance value setting) to correct the error caused by the hysteresis characteristic.This method corrects the error caused by the hysteresis characteristic by changing the ratio of the current flowing to the motor phase depending on the direction of head access. It is.

[Problems to be Solved by the Invention] However, in the first method of the prior art described above, access for two caps must be made depending on the direction.The time required for this extra access is longer than the average access of the device. This amounts to 10 to 20% of the time, which is significantly contrary to the trend of shortening the access to Japanese Patent Application Publications in recent years. ff1
In method 2, the phase current ratio is constant because the resistance value is constant, and the value to be corrected is always a constant value. However, the amount of positioning error due to hysteresis characteristics is due to variations in hysteresis characteristics for each motor attached to the device, and
The variation in the frictional force of the head movement II1 mechanism and the variation in the voltage supplied to the motor also greatly differ. What is the original hysteresis correction value? Although it has to be changed depending on the S conditions, this method uses constant correction. Therefore, with this method, optimal correction cannot be made, and only the error due to the hysteresis characteristic is reduced, and a positioning error remains.

Therefore, the present invention is intended to solve these problems.
The purpose is to optimize the correction for removing errors caused by hysteresis characteristics depending on the equipment and usage conditions, dramatically improve head positioning accuracy, and enable high-density track pitch. and provide high-capacity magnetic storage devices.

[Means for Solving the Problems] The magnetic storage device of the present invention detects the amount of positioning error at least every time the device is started up by means of detecting the amount of positioning error due to the hysteresis characteristic of the head moving mechanism, The present invention is characterized in that the positioning error is corrected by changing the current ratio applied to the excitation phase of the head drive motor in accordance with the positioning error.

[Operation] According to the above configuration of the present invention, the positioning error due to the hysteresis characteristic, which differs depending on the device and the usage conditions of the device, is detected by the error detection means at least when the device is started, and the positioning error is detected in each device usage environment, The correcting means can be used to perform the optimum error correction that meets the conditions at that time, thereby dramatically improving positioning accuracy.

Examples] FIG. 81 is a block diagram showing an embodiment of the present invention.

The disk (1) is rotated by a spindle motor (2). A head (3) writes or reads signals on the disk surface.

The head is fixed to a carriage (4).

The carriage (4) converts the rotation of the rotary shaft of a head drive motor (step motor) (5) into linear motion using a belt (6), and moves linearly in the radial direction of the disk. A symbol (71) (FIG. 7) is written on a part of the disk surface, which is used for detecting positioning errors due to hysteresis characteristics. (7
) is the head output playback 1■1 path, and the detection signal (71)
Play. (8) is an A/D converter and the detection signal (
71) into a digital value.

(9 is a microprocessor, which calculates a correction value for the positioning error amount based on the hysteresis characteristic and commands the motor excitation current value based on the correction value. (10), (9
) is a RAM that stores correction values calculated by the microprocessor. Motor excitation circuit (13) (14)
is 1 commanded by the microprocessor in (9)
'tf is a constant current excitation circuit that supplies the current value to the motor.

The constant current value of this excitation circuit is determined by an external reference voltage. This reality voltage is obtained by water passing the current setting value (digital value) from the microprocessor through the D/A converters (11) and (12). A D/A converter and an excitation circuit are provided for each of the A and B phases of the motor, and the current flowing through the excitation phase of the motor can be changed arbitrarily according to the current setting value (digital value) from the microprocessor. For example, set the digital value of the current setting value only to 1 for the A phase.
When it is increased, the A-value current increases slightly and the stopping position of the stepping motor changes, allowing the head to be moved slightly. In this way, the head can be moved by changing the motor current setting value (digital value) and changing the current ratio of the excitation phase.

The method for detecting positioning errors due to hysteresis characteristics is shown below. Figure 8 shows the procedure for detecting positioning errors. The relationship is from the center of the track (N-1) as shown in Figure 9.
l - It is written on the ivy side. Disc outer circumference ((N-1)
truck).

When accessing N tracks from Access N tracks from N+1)) rack). The head gap at this time is (92)
The positional deviation (93) between the 0th position fi (91) and the position (92) is a positioning error due to the hysteresis characteristic. A/D the envelope voltage of No. 48 at (92)
Convert it to Ain. Comparing Aout and Ain, Aout is larger, so change the A phase (or B phase) motor current setting value by 1 and move the head to the outer circumference.

The gap position of the head at this time when it moves slightly to (
Tll!I!IJ from (92) to (94).The envelope voltage of the signal output at this time is A/D converted and Ain
Let's compare it with the above-mentioned Aout. The head gap is (9
1), so Aout is still larger. Therefore, the A-phase (or B-phase) motor current setting value is further changed by 1, and the head is slightly moved to the outer periphery. At this time, the head gap position is from (94) to (95)
).

At this time, the envelope voltage of the signal output is A/D converted and set as Ain, which is compared with the above-mentioned Aout.

Since the bed gap matches (91), Aout
and Ain become equal. A phase (or B phase) up to this point
The current setting value change (Nad) is memorized. In this example, since the ° current change was performed twice, the detection of the position error amount Nad caused by the hysteresis characteristic was completed by the procedure of 0 or more where Nad=2. Means for detecting (15)
are (71), (3), (7), (8)', (9), (
IB, (12), (13), (14), (5), (6)
, (4). It can be seen that when the head is accessed from the inner circumference to the outer circumference, the position error can be eliminated by correcting the head by Nad to the outer circumference. The detection of the position error 1 Nad caused by the hysteresis characteristic is performed for each '! ! A method for correcting positioning errors caused by hysteresis characteristics will be described below, which is performed at least when the equipment starts to be used (i!IJ) at J and m. The procedure for correcting the head positioning error is shown in FIG. 1O. Based on the access command, it is determined whether the access direction is toward the outer circumference or the inner circumference. If it is from the inner circumference to the outer circumference, the positioning error (9
There is a difference of 3). In order to correct this, the correction value Nad obtained by the above-mentioned correction value detection means is read from the RAM, and the fluid film constant value of the motor A phase is changed by Nad, the current flowing to the motor phase is changed, and the head is moved to the outer peripheral position (95). This eliminates positioning errors due to hysteresis characteristics.

If the access is from the outer circumference to the inner circumference, there is no need to make any correction, and the motor is excited without making any correction.

As described above, the means (16) for correcting positioning errors due to hysteresis characteristics includes (9), (10), and (11).
, (12), (13), (14), (5), and (6).

Positioning error detection means described in this embodiment.

The correction means is just one example, and any device that satisfies the IT71 function may be used. Also, correction value detection can be performed not only when the device is started up, but also when the device is started.
It goes without saying that you can do it at any time.

[Effects of the Invention] As described above, according to the present invention, the positioning error due to the hysteresis characteristic of the head movement mechanism part of the magnetic storage device and the head drive motor is detected at least every time the device is started, and the positioning error is detected at least every time the device is started. By changing the ratio of the current flowing through the excitation phase according to the amount of positioning error, it is possible to eliminate the positioning error. This made it possible to increase the track density of magnetic storage devices, allowing more tracks to be placed on the disk surface and increasing capacity.

In addition, the present invention detects the amount of positioning error for each device at least when the device is started. This allows for the main friction of the head moving mechanism that differs depending on the device, variations in the characteristics of the head drive motor, and variations in the usage conditions of the device. (temperature, power supply voltage)
Even if there is a problem, it is possible to perform the optimum correction for the usage conditions of the device at that time, and eliminate positioning errors. This results in
The reliability of the equipment has been dramatically improved and high reliability has been achieved.

As a result of these things, the present invention has a great effect on increasing the capacity and reliability of magnetic storage devices.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating an embodiment of the present invention. FIG. 2 is a perspective view of a conventional magnetic storage device. FIG. 3 is a diagram showing the results of measuring hysteresis of the carriage. FIG. 4 is a diagram showing an access method for performing hysteresis correction in the prior art. FIG. 5 is a diagram of a conventional hysteresis correction circuit. FIG. 6 is an excitation timing diagram of a conventional hysteresis correction circuit. FIG. 7 is a diagram showing a positioning error detection signal due to hysteresis characteristics. FIG. 8 is a flow diagram showing positioning error detection means using hysteresis characteristics. FIG. 9 is a diagram showing a positioning error detection method using hysteresis characteristics. FIG. 10 is a flowchart showing a procedure for correcting positioning errors due to hysteresis characteristics. l・・・・・・・・・Magnetic storage medium (disk)
2・・・・・・・・・・・・Spindle motor 3.22
...Head 4.23...Carriage 5.21...Head drive motor (stepping motor) 6...Belt 7...・Head output playback circuit 8・・
・・・・・・・・・A/D converter 9・・・・・・・・・
...Micro Flosser 10...
・・Correction value storage unit (RAM) ll・・・・・・・・・・
・・A phase D/A converter 12・・・・・・・・・・・・
B-phase D/A converter 13...A-phase motor excitation circuit 14...B-phase motor excitation circuit 15... ...... Means for phase-detecting positioning errors due to hysteresis characteristics 16 ...... Positioning errors due to hysteresis characteristics? ll pressure means 51, 52, 53, 54, 55, 56, 57゜58...
......Transistors 59, 60, 61.
62...Resistance 63.64, 65.68...
...Coil 71...Correction value inspection signal 91... (N-1)) Head gap position when accessed from the rack 92・・・・・・・・・・・・(N+1) Herad gap position when accessed from the track 93・・・・・・・・・Positioning error due to hysteresis characteristic 94.95... Head gap position after correction Figure 6 Figure 6 Figure 8 Figure 7 Figure 9

Claims (1)

[Claims] In a magnetic storage device comprising a magnetic storage medium, a head that moves on the surface of the medium to perform recording and reproduction, a head movement mechanism having hysteresis characteristics, and a head drive motor, the head movement mechanism and the head drive motor have hysteresis. The means for detecting the amount of positioning error based on the characteristics detects the amount of positioning error at least every time the device is started, and the ratio of the current flowing through the excitation phase of the head drive motor is changed in accordance with the amount of positioning error. A magnetic storage device characterized in that the positioning error is corrected by.