JPS60136975A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the head positioning accuracy by measuring in advance a head positioning error at each set after assembling of the device, storing the correcting value at each set and controlling the head position with the value to absorb the head positioning error. CONSTITUTION:A voltage to be applied to windings A and B to zero the positioning error as to each track after the end of assembling is measured. The voltage values are written in a PROM12. A signal zeroing the position error is read out of the PROM12 at each track in response to an output of a track counter 11 when the device is driven and a stepping motor 1 is stopped to a position where the positioning error is zero by a converter 13 and a stepping motor driver 14. When an SIDE signal is switched and an address of the PROM12 is changed, an output data is changed, the step motor 1 is displaced minutely, the magnetic head 7 or 8 is positioned correctly and malfunction is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic recording and reproducing device, and particularly to a magnetic recording and reproducing device that uses a stepping motor to position a magnetic head.

[Background of the invention]

In a conventional magnetic recording/reproducing device in which a magnetic disk such as a floppy disk is removable, the positioning error of the magnetic head is required to be below a certain tolerance value in order to maintain compatibility between the devices. This tolerance varies depending on the number of tracks per unit length (track density) and the configuration and dimensions of the magnetic head, but if you use a tunnel erase type head that has guard bands on both sides of the data,
The value roughly corresponds to the tunnel erase gap width. Therefore, as track density increases, higher head positioning accuracy is required.

FIG. 1 shows an example of a head positioning device conventionally used in floppy disks. In Fig. 1, 1 is a stepping motor, 2 is a pulley press-fitted onto the shaft of the stepping motor, 3&''!, a steel belt, 4
is a rail fixed to the chassis (not shown) of the floppy disk drive, 5 is a carriage, 6 is a head arm,
7 and 8 are magnetic heads, 9 is a chucking device for fixing a magnetic recording medium (floppy disk) (not shown) to a floppy disk drive, and 10 is a reference track position sensor.

In the operation of the head positioning device, first, the rotation angle of the stepping motor 1 fixed to the chassis changes in a stepwise manner according to a control signal. Therefore, the pulley 2 also rotates in a stepwise manner. The rotation of the pulley 2 causes the carriage 5 to move linearly along the rail 4 via the steel belt 6. That is,
The carriage 5 makes discrete linear movements in accordance with the stepped rotation of the stepping motor 10. Since the stepping motor 1 rotates at regular intervals, the carriage 5 performs linear motion at regular intervals. Therefore, the magnetic head 7.8 attached to the carriage 5 and the head arm 6 fixed to the carriage 5 moves linearly at regular intervals.
By setting this interval to the interval between tracks (the reciprocal of the track density), the magnetic head is positioned at the track position. Note that the reference track position sensor 10 is connected to the carriage 5.
By detecting the position of the magnetic head, it is possible to know when the magnetic head has reached the reference track position (usually the outermost track position).

Positioning error factors in a magnetic recording/reproducing device using such a tasteful head positioning device include (1) angular error of the stepping motor (usually about ±6% of the rotation angle), and (2) absolute value accuracy of the pulley diameter. , (3) 1m degree of installation of the rail to the chassis, (4) Chucking accuracy of the magnetic disk, (5) Expansion and contraction of the magnetic disk due to temperature and humidity, (
6) There are errors in the installation of the two upper and lower heads. In the current magnetic recording/reproducing device using a 3-inch diameter magnetic disk, the total of these is about 80 μm, and due to the tunnel erase width limitation described above, the range is 100 TPi (tracks/inch; number of tracks per inch) to 1s o T.
The track density is limited to about Pi, which is an obstacle to increasing the density.

[Purpose of the invention]

An object of the present invention is to provide a magnetic recording and reproducing device that uses a stepping motor to position a magnetic head and is capable of improving head positioning accuracy and realizing high-density recording. be.

[Summary of the invention]

The present invention addresses (1) among the above-mentioned positioning error factors;
f21. (By reducing the magnetic head positioning error caused by factors 31 and (6), head positioning accuracy is improved by reducing head positioning error. Head positioning error due to these factors is It differs from device to device and from component to component, and therefore from magnetic recording/reproducing device to magnetic recording/reproducing device, and even from track to track.

In the present invention, the head positioning error after device assembly is measured in advance for each unit, the drive unit is equipped with a means for correcting the error, and the correction value is stored for each unit,
By controlling the head position using this value, head positioning errors are absorbed and head positioning accuracy is improved. The positioning error correction is realized by utilizing the fact that the rest position of the stepping motor after stepwise rotation changes slightly by controlling the internal magnetic field of the stepping motor.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 2 shows an embodiment of the present invention. In Fig. 2, 1 is a stepping motor, 11 is a track counter, and 12 is an F
ROM (Program pull read only memory), 13
is a converter, 14 is a stepping motor driver, 15 is an oscillator, 16 is a frequency divider, 19 is a delay circuit, 20 is a timer circuit, 21 is a signal readout circuit connected to the magnetic head,
22 is a signal output terminal. First, the input signal will be explained. 5TEP is a signal sent from a higher-level controller to move the magnetic head by one track. In this embodiment, the stepping motor rotates by a certain angle every 91 times of falling of 5TEP. DIRECTIO
N is also a signal from the higher-level controller that indicates the rotation direction of the stepping motor, and when this signal is low level,
The magnetic head moves toward the inner track of the magnetic disk.

(2) φ is the output of the reference track position sensor 10 shown in FIG. 1, and becomes low level when the magnetic head 7.8 reaches the reference track position. 5IDE is a signal for selecting the upper and lower heads, and when 5IDE is at the no-no level, the lower of the two heads shown in FIG. 1 is normally selected as head 8.
is selected (signals are recorded and reproduced by the lower head).

), the upper head 7 is selected when the level is 4-level.

Further, the Pσ■RON signal is a signal that becomes high level when the power supply of this system rises.

The operation of each part will be explained. When the power is turned on, the track counter 11 moves the magnetic head 7.8 to a reference track position (the outermost track of the magnetic disk, which is usually the track number 0).
, the upper two tracks are incremented by 1 each time the track is moved inward one track) and reset (adjusted to α). Usually, the track number is indicated by a count or a count DC%'/N by the 5TEP and DIRECTION signals from the higher-level controller. The lower two pits Qo, Q, of the binary value of the track counter 11 are applied to the terminal of the stepping motor driver 14 through the EOR gate, and Ql is similarly applied to the terminal.

Therefore, the stepping motor driver 14 glue, ,D
.

The track counter 11 is immediately connected to the terminal (
The change in DI, D, ) is (o, o) → (o, 1) → (1
, 1) → (1, o) → (0, 0) →... is repeated. In addition, count [sometimes, (0,0)→(1,0)→(
1, 1) → (o, 1) → (a, O)... and repeat.

The stepping motor driver 14 is, for example, IC, HA, 13421P manufactured by Hitachi, Ltd., and FIG. 2 shows its operating principle. The current depending on the input voltage of E is D
When the 1 terminal is at the 4- level, the switching transistor Q* -Q- is turned on, causing the current to flow in the α direction of the A winding of the stepping motor 1, and when the terminal is at the high level, the switching transistors Q, , Q4 When turned on, the light flows in the b direction. That is, El and E
! The voltage applied to Dl increases, and the direction is controlled by the input signal to the terminal to drive the stepping motor 10A.
and applied to winding 8. Therefore, if, for example, a no-brid type stepping motor MSHD200 manufactured by Sankyo Seiki is used as the stepping motor 1, the signal D changes as described above due to the count value of the track counter or the run 1-[. The magnetic field inside the stepping motor 1 rotates as shown in FIG. 3, causing the stepping motor 1 to rotate. Therefore, the magnetic head moves one track at a time.

Next, correction of positioning errors will be explained.

FIG. 4 shows actual measured values of minute static position changes when controlling the voltage of the windings of the stepping motor. A in the same figure is A
Winding IWjiB shows the rest position of the stepping motor when the voltage ratio applied to the winding is changed. The horizontal axis shows the voltage of the winding B and the voltage of the B winding, and the vertical axis shows the rest position. It can be seen that the rest position can be controlled by ±1/2 steps by controlling the voltage from the balanced position when the same voltage is applied. Therefore, by controlling the voltages of the A and 8 windings, the magnetic head can be positioned at any desired position. Also, B in the same figure is the A winding.

It shows the rest position when the duty ratio of the voltage applied to the 8th winding is changed by PWM (Pulse Width Modulation) modulation. It can be seen that by changing the duty ratio of the winding B, the rest position can be controlled in the same way as when changing the voltage ratio.

Correction of positioning error is performed as follows.

First, after assembly is completed, the voltage (or duty ratio) to be applied to the A winding and B4#I in order to make the positioning error zero is measured for each track. (Normally, it is known that a special signal for measuring the positioning error is written on the disk and the positioning error is measured by reading this signal with a magnetic head.) This voltage value or 1) Write data corresponding to uty to FROMl 2 in FIG. Therefore, correction data for setting the positioning error to 0 is written in the FROM 12 for each drive and each track.

Therefore, when using this drive, the signal to set the positioning error to 0 for each track is sent to the track counter 1.
In response to the output of PRO1'1d12, the converter 15 and stepping motor driver 14 stop the stepping motor 1 at a position where the positioning error becomes zero.

The method described above eliminates positioning errors between tracks to zero.
However, in the magnetic recording/reproducing apparatus described in the present invention in which two heads are arranged above and below, it is better to have the track position alignment of the upper and lower heads also performed by this system. This upper and lower head alignment error is approximately 5 to 10
μm exists. Therefore, the head positioning error caused by the vertical head alignment error can be absorbed using the same method as the correction of the head positioning error between tracks described above. This will be explained below. The 5IDE signal is input to the FROMI 2 address. Therefore, FROM has 5 IDE levels (
Correction data can be stored individually depending on the selection of the upper and lower heads, and head positioning errors caused not only between tracks but also due to 5IDE can be corrected. However, this method has drawbacks. This is because conventionally, the 5I
DH switching is instantaneous (because it does not involve head movement).
In the conventional specification, this could be done in less than 0.1 m5 ec), but according to this embodiment, the switching time is equal to the head movement time. FIG. 8 shows how the head moves when switching between 5 IDEs according to this embodiment. As is clear from the figure, it takes 3 to 4 m3ec. Therefore, if a signal is recorded or reproduced within this time, there is a risk that a signal error will occur because the head is not positioned at the correct position.

Therefore, in FIG. 2, when the 5IDE signal is switched and the address of FROMl 2 changes, FROMl 2
The output data changes and the step motor 1 is slightly displaced,
Position the magnetic head 7 or 8 at the correct position.

At that time, the delay circuit 19 and the exclusive logic a (EOR'
) A pulse indicating a change in the 5IDE signal is given to the timer circuit 20 by the 5IDE switching detector constituted by EOR2, and the Q output of the timer circuit is set to a low level for a certain period of time. Therefore, regardless of the reproduced data of the signal readout circuit 21, the output of the signal output terminal 22 is NAND.
When the gate input becomes O, it is forcibly set to a high level, and the reproduced data is not sent to the upper system.

Therefore, when the head is switched, the signal is not read out for the time set by the timer circuit 20. Therefore, if this system is driven by a conventional floppy disk controller, the signal is not interrupted and malfunctions are avoided.

It is clear that the time set for the timer circuit 20 should be longer than the time required to move the head, as shown in FIG.

Next, a specific example of the configuration of the converter 13 shown in FIG. 2 will be explained. FIG. 5 shows an example of a configuration using a D/A converter (digital/analog converter). 12 is a FROM, 17 is a converter, and 14 is a stepping motor driver. The data written in FROMl 2 is the D/A
It is converted into an analog voltage value by the converter 17, and the input terminals E, , E, of the stepping motor driver 14 are driven at a constant voltage by the driver transistors Q and Qs. Therefore, this is a method suitable for controlling with the voltage shown in FIG. 4 (2).

However, this method has the disadvantage that it generates a lot of heat due to the unsaturated operation of Q, , Q.
Since it is driven at a constant voltage, it has the advantage of not generating switching noise.

FIG. 6 shows a method of changing the duty using another configuration example. 15 is an oscillator, 16 is a frequency divider, 12 is F
ROM, 18 is a digital comparator, and 14 is a stepping motor driver. The frequency divider 16 always divides the pulses of the oscillator 15 into binary values. Therefore, a carry occurs at every fixed pulse and resets the flip-flops FF2 and FF3. The digital comparator 18 compares the output value of the PROM 12 and the output value of the branching unit 16, and if they match, sets the respective 7 lip-flops FF2 or FF3. Therefore, a signal of I)uty according to the value of FROM is generated in FF2 and FF5, and Qu
and Q2. Switching. Therefore, the input terminals of the stepping motor driver 2 are FR
Vcc with a duty ratio according to OM data is applied.

This method is efficient because Qu+Qu operates in saturation, but it has the disadvantage of generating switching noise.

Next, in this system, if the actual track position and the value of the track counter 11 do not match, the desired correction data will not be output correctly from the FROM 12.
It is necessary to reset the track counter 11 when the power is turned on. The timing chart at power up is shown in 7th
As shown in the figure.

When the PmRON signal rises, the flip-flop FF1 is set, and the track counter 11 consisting of an active down counter enters the count mode. Oscillator 15
The output pulse is frequency-divided by the divider 16 and becomes NA1￥
It is applied to the CLK terminal of the passing track counter 11.

At this time, the 5TEP signal is.

(by a gate (not shown)). Normally, the output pulse period of the branching unit 16 may be set to about several mf3ec. Therefore, the track counter 11 counts m every amset, and the stepping motor is rotated to move the magnetic head in the direction of the reference track. When the magnetic head reaches the reference track position, the signal φ from the reference track position sensor 10 becomes low level, resetting the flip-flop FF1 and resetting the track counter 11. Therefore, the value of the track counter 11 and the actual track position match, and from then on, in response to the 5TEP and DIRECTION inputs, the magnetic head 7.8 is positioned at a position with less positioning error by the correction operation as described above. Ru.

Although the above description has been made based on a floppy disk, the present invention is not limited only to floppy disks, but can be widely used in open-loop position control systems using stepping motors.

In addition, in the example of the converter that changes the duty ratio shown in FIG. 7, by operating El and E complementary, the number of digital comparators 18 is reduced to one, and the FF
It is also possible to exclude 5.

Further, the FROM may be any non-volatile storage means, and it is clear that it may be a RAM (Random Access Memory) backed up by a battery, regardless of whether it is an ultraviolet erased WROM or a mask ROM.

〔Effect of the invention〕

According to the present invention, it is possible to improve the positioning error of an open loop head positioning device using a stepping motor. Especially double head type (double-sided type)
Even in the positioning device, the positioning accuracy can be improved without malfunction. Positioning error is ±20μm
The recording density has been improved to 5 voices, and even on 3-inch floppy disks, the sum of all error factors can be improved to approximately ±22 μm, making it possible to increase the recording density to 200 TPi, which is twice the conventional recording density. .

[Brief explanation of drawings]

Fig. 1 is a perspective view of a conventional head positioning device, Fig. 2 is a circuit diagram of an embodiment of the present invention, Fig. 3 is a principle diagram of stepping motor rotation, and Fig. 4 is a characteristic showing the control characteristics of the stepping motor. Figures 5 and 6 are circuit diagrams of the converter, Figure 7 is a timing chart when the power is turned on, and Figure 8 is the circuit diagram of the converter.
FIG. 7 is a characteristic diagram showing an example of the head position when switching the IDE signal. 1.Tipping motor, 7.8:Magnetic head, 10
: Reference track position sensor, 11 Ni track counter, 12 : FROM. 13: converter, 14 chipping motor driver, 19: delay circuit, 20: timer circuit, 21: signal readout circuit. Figure 3 Figure 4 ioo % = /2 Y Figure 4/, ) /l. Figure 7

Claims (1)

[Claims] t A magnetic recording/reproducing device that positions the head using at least a stepping motor is provided with a means for counting tracks and a nonvolatile data storage means, and the data storage means is provided with a head positioning error in advance. A magnetic recording/reproducing device characterized in that a value to be corrected is stored and the stepping motor is controlled based on the value. 2. In a magnetic recording/reproducing device where multiple magnetic heads are installed, positional errors are corrected by controlling a stepping motor, a head switching detection circuit and a timer circuit are installed to disable the reproduced data for a certain period of time after switching heads. A magnetic recording/reproducing device according to claim 1, characterized in that the magnetic recording/reproducing device generates a signal.