JPH02281479A - Magnetic flexible disk drive device - Google Patents

Abstract

PURPOSE:To accurately perform tracking servocontrol even when tracks are provided with high density by setting a head in the center of a track at a part where a head position shifts linearly and performing microstep driving. CONSTITUTION:A current which is a 1st sine wave and a current which is a 2nd 90 deg.-delayed sine wave are supplied to a stepping motor to perform the tracking servocontrol by the microstep driving. Then, when a current having an electric angle which is nearly 45+90 deg.Xn (n: integer) is passed according to the zero point of the 1st sine wave used for the microstep driving, the head is positioned in the center of the track. Consequently, even if a slight deviation is caused, the head position is corrected to follow the track. Consequently, even when a magnetic flexible disk have tracks with high density, the tracking servo is accurately performed.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a magnetic flexible disk drive device that performs tracking servo.

[Conventional technology]

The head of a magnetic flexible disk drive device is
It is moved to a position directly above the tracks of a magnetic flexible disk, and is used to read and write data. Movement of the head is typically accomplished by a stepper motor. When the track density of a magnetic flexible disk is low, it is moved to the track position by full step driving of a step motor. Full step drive uses the step motor's two-phase coil (
This drive is performed by passing step currents with a phase shift of 90° as shown in FIG. 3 through the A-phase coil and B-phase coil. For example, at the electrical angle of 90', +I current is flowing through the human phase and 0 current is flowing through the B phase. In full step drive, the step motor rotates in steps by a fixed angle determined by the number of teeth, etc.
stabilize in that position. Steps driven like that
The head is also moved in steps by the motor,
Its moving position is just above the trunk. However, due to the demand to store as much data as possible on a single magnetic flexible disk and advances in technology, the track density of magnetic flexible disks has decreased.
The density is gradually increasing. On the other hand, depending on the material used as the base of the magnetic flexible disk (for example, mylar), it may deform due to temperature or humidity, and the circumference of the track may also become distorted. In order for the head to accurately track the trunks that are arranged in high density and are distorted, it is necessary to delicately adjust the head position, but this cannot be done with the full step drive described above. This led to the idea of microstep drive. Microstep drive uses two sine waves with a phase shift of 90', rather than passing only three types of current, +■ and 0°■, through the A and B phase coils of the step motor as shown in Figure 3. This is a drive in which a current is passed at the same electrical angle, and is performed in smaller steps (microsteps) than full-step drive. Figure 2 is a diagram explaining microstep drive. ) are sine wave currents whose phases are shifted by 90 degrees from each other.Although they are called sine waves, they are not actually waveforms that change smoothly (as shown in the enlarged view of the part, it is a sine wave current that can be seen microscopically). For example, the waveform changes in a step-like manner.The reason for doing so is to store the sine waveform as a digital quantity.Figure 2 (b) shows the waveform when the current value in (a) is applied. This is an example of the rotation angle of the step motor when the electric angle is 9.
When the current is 0@, a current of +■0 is passed through the A-phase coil and ■0 through the B-phase coil, but the rotation angle of the step motor at this time is
When the position at an electrical angle of 0° is used as a reference, it is 0.9°. FIG. 2(c) is an example of an address of a current value storage device that stores a combination of values obtained by dividing a sine wave into steps. In this example, since addresses up to 100 are shown in hexadecimal notation, one period of the sine wave is divided into 256 parts. The fineness of the stairs also varies depending on the number of divisions. Each address stores a set of current values to be passed through the A-phase coil and B-phase coil. For example, at address 40 (+l, 0)
A set of is stored. Also, the value of the A-phase sine wave when the electrical angle is ' is rAK, the value of the B-phase sine wave is I□, and these values are written f, I! AD address for each
AK, AD□ address. By doing this, by selecting an address,
This makes it possible to control the current flowing. if,
If addresses AD□ and AD111 are selected for A phase and B phase, respectively, the rotation angle of the step motor is approximately 0.9XK.
/90, making it possible to perform small step rotations (in full-step drive, after 0°, 0.9°,
After that, it can only rotate in large steps of 1° and 8°. ). As a result, the head can be moved in minute units, and tracking servo (moving the head by tracking a track), which was impossible with full-step drive, has become possible.

[Problem to be solved by the invention]

(Problem) In the conventional technology described above, due to the custom from the time of full-step drive, the head position is adjusted so that the head position at the electrical angle of 90° x n (n is an integer) corresponds to the center position of each track. Adjusting the position. However, this has the problem that it is not possible to move the head position by a small amount, and it is not possible to deal with a slight off-track (deviation from the track). (Explanation of the problem) FIG. 1 is a diagram showing the relationship between the electrical angle of the current waveform and the head position in microstep driving.
As shown in the figure, in the vicinity of an electrical angle of 90° x n (n is an integer) (for example, in the vicinity of 0° 90180°), the relationship between the electrical angle and the head position is not linear, but rather flat. (Part N. To avoid complicating the drawing, only the part corresponding to around 180 degrees of electrical angle is given the symbol N.) Therefore, even if the electrical angle is changed near N, the head position hardly moves. In this case, tracking servo cannot be performed accurately. An object of the present invention is to solve the above-mentioned problems.

[Means to solve the problem]

In order to solve the above problem, the magnetic flexible disk drive device of the present invention supplies a first sine wave current and a second sine wave current delayed by 901 points to the step motor, and In a magnetic flexible disk drive device that performs tracking servo by driving, when a current with an electrical angle of approximately 45° + 90° × n (n is an integer) is passed with respect to the zero point of the first sine wave, I decided to set it so that the head was located in the center of the track.

[For production]

In microstep drive, when we look at the relationship between the current flowing through the step motor and the head position, we find that it is approximately 45° + 90'Xn (n is an integer), the head position changes in sensitive response to changes in the electrical angle. That is, the position of the head can be controlled extremely precisely. Therefore, if the head is positioned at the center of the track when a current with an electrical angle of approximately 45' + 90° x n (n is an integer) is applied, even if a slight deviation occurs, the head You can adjust your position and follow the track. Therefore, even if the magnetic flexible disk has high track density, tracking servo can be performed accurately.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. According to Fig. 1, it is nonlinear near 90'' (The M part. In order to avoid complicating the drawing, only one symbol is attached.) In the present invention, focusing on this point, the electrical angle is 45＠+90°×
When a current corresponding to time n is passed through the A and B phase coils,
The head position was adjusted so that it was in the center of the track. Then, when currents corresponding to slightly different electrical angles are passed through each coil, the head will also move in a linear relationship, allowing fine tracking servo to be performed. FIG. 4 shows a magnetic flexible disk drive device according to an embodiment of the present invention. In FIG. 4, l is a magnetic flexible disk, 2 is a spindle motor,
3 is a head, 4 is a head carrier, 5 is a steel belt, 6 is a pulley, 7 is a connecting shaft, 8 is a head amplifier, 9 10 is a timing switch, 11.12 is a peak hold circuit, 13 is a comparator, 14 is an A/D converter, 1
5 is a microprocessor, 16 is a current value recording fα device, 1
7.18 is a D/A converter, 19.20 is a Hower amplifier,
21 is an A-phase coil, 22 is a B-phase coil, and 23 is a step motor. The head position is adjusted so that the head 3 moves to the center position of the trunk when a current value corresponding to an electrical angle of 45" + 90' Xn (n is an integer) is applied to the A-phase coil 21B-phase coil 22. The step motor 23 rotates the pulley 6 via the connecting shaft 7. A steel belt 5 fixed to the head carriage 4 is wound around the pulley 6. By rotating, the hend carriage 4 is driven, and the head 3 fixed thereto is driven.
is moved in the radial direction of the magnetic flexible disk l. Note that H(t) indicates the position of the head 3 in the radial direction at time t. Tr (L) indicates the position of the track being tracked by the head 3 in the radial direction at the same time. When head 3 is directly above the track, H(t)
= Tr (t), which is a desirable figure. When the head 3 is not directly above the track, the degree of deviation is detected as follows. FIG. 5 is a partially enlarged view of a magnetic flexible disk that performs tracking servo, and data is recorded on the magnetic flexible disk l as shown in this figure. Vertical lines and diagonal lines written in alignment indicate recorded data. In the circumferential direction, servo pattern areas SPA are provided by cutting out some parts of the data area DA. Data area DA includes tracks Trl and Tr2.
．． Tr3 etc. are provided and data is written therein. In the servo pattern area SPA, there are two patterns 1, half of which cover the track, and which are shifted toward the inner circumference and the outer circumference.
．． 2 is written. This pattern 1.2 is used to detect the deviation of the head 3 from the track. Assume that the track currently being tracked by head 3 is Tr2. (A), (B) and (C) in FIG. 5 show typical cases of the position of the head 3. (b) is the case just above track Tr2 (on-track state);
(A) is the case when the disc is displaced toward the outer circumference, and (C) is the case when the disc is displaced toward the inner circumference. Cases (a) and (c) are off-track conditions, and in these cases, it is necessary to correct the head and end position so that it becomes the position (b). FIG. 6 shows detection signals for tracking servo. (A), (B), and (C) in Figure 6 are (A) in Figure 5.
, (b) and 5 (c) respectively. This detection signal is obtained by amplifying the signal read by the head 3 by the head amplifier 8 when the head 3 passes over the servo pattern area SPA from left to right. In the case of (a), since it is shifted toward the outer periphery, it passes over pattern 1 while largely covering it, but pattern 2
covers only a small amount. Therefore, the peak value of the signal obtained by pattern l is
, is large, and the peak value vt of the signal obtained by pattern 2 is small. That is, V,>V. In the case (b), V+ and Vg are approximately equal. In case (c), it is the opposite of case (a), so V,
<V. During the period in which the head 3 detects the signal of pattern I, the timing switch 9 is turned on, and the peak value (1) is held in the peak hold circuit 11. Similarly, during the period in which the signal of pattern 2 is detected, the timing switch 10
is turned on, and its peak value Vt is peak hold times i
It is held at i@12. The comparator 13 compares ■1 and v2. This results in (
It is possible to know which case (a), (b), or (c) is occurring, and the extent of the deviation. The difference between the two is converted into a digital quantity by the A/D converter 14, an address is determined based on this digital quantity, and the current value storage device 16 is accessed using the address. For example, in FIG. 1, suppose that while tracking a track consisting of a head position corresponding to an electrical angle of 135@, it is detected that an off-track state occurs because the track is distorted. If we assume that in order to enter the on-trunk state, it is necessary to move the head position a little towards the position α (see the vertical axis in Figure 1), then the current at an electrical angle slightly smaller than 135° The address storing the value is determined, and the current value storage device 16 is stored at that address.
access. As a result of the access, digital signals indicating the current values to be passed through the A-phase coil and B-phase coil are obtained, but these are converted into analog quantities by D/A converters 17 and 18, respectively.
A phase coil 21. via power amplifier 19.20. The current flows through the B-phase coil 22. As can be seen from the fact that the head position changes linearly near the electrical angle of 135° (portion M), even if the electrical angle is only slightly changed, the head position changes in proportion to the electrical angle. The step motor 23 rotates to move in the direction α in FIG. This enables precise tracking servo.

【Effect of the invention】

As described above, the magnetic flexible disk of the present invention
According to the drive device, microstep drive is performed by setting the head so that it is located at the center of the track in the part where the head position changes linearly, so even if the magnetic flexible disk has a high track density, tracking is possible. Servos can now be used with precision.

[Brief explanation of drawings]

Figure 1: Showing the relationship between the electrical angle of the current waveform and the head position in microstep drive Figure 2: A diagram explaining microstep drive Figure 3: Current during full step drive Waveforms Fig. 4: Magnetic flexible disk drive device according to an embodiment of the present invention Fig. 5: Enlarged view of a portion of the magnetic flexible disk that performs tracking servo Fig. 6: For tracking servo In the detection signal diagram, l is a magnetic flexible disk, 2 is a spindle motor, 3 is a head, 4 is a head carriage, and 5
6 is a steel belt, 6 is a boot 9. 7 is a connecting shaft, 8 is a head amplifier, 9. 10 is a timing switch, 11
．． 12 is a peak hold circuit, 13 is a comparator, 14 is A
/D converter, 15 is a microprocessor, 16 is a current value storage device, 17.18 is a D/A converter, 19.20 is a power amplifier, 21 is an A phase coil, 22 is a B111 coil, 23 is a step motor It is. Patent Applicant Fuji Xerox Co., Ltd. Representative Patent Attorney Tomio Honjo

Claims (1)

[Claims] In a magnetic flexible disk drive device that supplies a first sine wave current and a second sine wave current delayed by 90 degrees to a step motor, and performs tracking servo by microstep drive, the first A magnetic flexible device characterized in that the head is positioned at the center of the track when a current with an electrical angle of approximately 45° + 90° × n (n is an integer) is passed based on the zero point of the sine wave of Disk drive device.