JPH0512786A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent a magnetic head and a recording medium from being damaged if the magnetic head or recording medium comes to the limit of duration or if much dust is present. CONSTITUTION:Before information is read or written, an SPM driving current detecting circuit 8 measures the driving current of a spindle motor on plural tracks of the recording medium 1 and inputs the measured value to a microprocessor 11. The microprocessor 11 approximates a track-to-driving current characteristic with simple successive values according to the measured value to set a permissible value. When the output of the SPM driving current detecting circuit 8 as to a track in information reading/writing operation exceeds the permissible value, the microprocessor 11 stops driving the spindle motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device which avoids damage to a magnetic head or a recording medium.

[0002]

2. Description of the Related Art FIG. 8 is a head support mechanism of a conventional magnetic disk device as shown in, for example, "All of floppy disk devices / from basics to applications of all types of FDD" P73 to P79 issued by CQ Publishing Co., Ltd. 2 is a recording medium, 2 is a spindle center, 3 is a magnetic head side 0 head, 4 is a magnetic head side 1 head, and 5 is a side 0 head 3.
A leaf spring that pressurizes the side 0 gimbal and a leaf spring 6 that presses the side 1 head 4 to the recording medium 1 are side 1 gimbals.

In such a structure, the side 0 gimbal and the side 1 gimbal operate to improve the adhesion between the side 0 head and the side 1 head and the recording medium 1.

[0004]

Since the head support mechanism of the conventional magnetic disk drive is constructed as described above, the magnetic head and the recording medium are always in a state of rubbing when writing and reading information. . If the magnetic head or the recording medium that has reached the endurance limit due to this abrasion or the like is used as it is, there is a risk that the side that has reached the endurance limit may be destroyed and the other side may be destroyed. In addition to the above case, such a state also occurs when there is a large amount of dust or dirt on the recording medium.

The present invention has been made in order to solve the above problems, and it is possible to detect an abnormal condition such as the endurance limit due to abrasion or the like, and an abnormal condition such as a large amount of dust or dirt on a recording medium. An object of the present invention is to obtain a magnetic disk device capable of avoiding the destruction of the magnetic head or the recording medium caused by the continuous state.

[0006]

In the above abnormal condition, the wear coefficient between the magnetic head and the recording medium changes greatly. This means that the load of the drive circuit of the spindle motor changes greatly, and therefore the current of the drive circuit also changes greatly. The magnetic disk device according to the present invention comprises a measuring means for measuring the current of the drive circuit, and an approximation means for approximating the track-to-drive current characteristics measured in a plurality of tracks before the information read / write operation by a simple continuous value, Tolerance value setting means for setting an allowance value for an approximate value is provided, and when the drive current measured by the measuring means in the track during the reading and writing of information exceeds the above-mentioned allowance value, the spindle motor drive is stopped. It is the one.

Further, the drive of the spindle motor is stopped after the end of the reading / writing operation in progress.

[0008]

In the magnetic disk device according to the present invention, the allowable value of the spindle motor drive current is set according to the recording medium or track actually used, and when the drive current during the information read / write operation exceeds the allowable value, the spindle motor drive current is set. Stop the motor drive.

If the allowable value is exceeded, the spindle motor drive is stopped after the reading / writing of information is completed.

[0010]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, 7 is a spindle motor drive circuit (hereinafter, SPM drive circuit), and 8 is a drive current of the SPM drive circuit 7 (hereinafter, SPM drive current). An SPM drive current detection circuit for detecting, 11 is a microprocessor for detecting an abnormality of the SPM drive current and taking countermeasures, and 12 is an indicator (hereinafter, LED) for displaying an abnormal state. 2 and 3 are flow charts for explaining the operation of the embodiment of the present invention.

The operation of FIG. 1 will be described with reference to the flowcharts of FIGS. Here, if the recording medium 1 is inserted (step 14), the spindle motor (hereinafter, SPM)
Are driven (not shown). Before the information read / write operation, the magnetic head is sequentially sent to a plurality of tracks (not shown), and the SPM drive current on each track is measured (step 15). Next, the microprocessor 11 approximates each measured value with respect to the increase of the track number by a regression line, and further obtains the allowable value of the fluctuation of the SPM drive current value at a specific ratio with respect to this approximated value (step 16). The respective measured values are compared with the allowable value (step 17), and if the result is within the allowable value, information writing, reading and track movement are enabled and normal operation is performed (not shown). . After that, during operation of the magnetic disk device,
The measurement of the SPM drive current value in the track where the magnetic head is present (step 19) and the comparison of the measured value with the above-mentioned allowable value (step 20) are repeatedly executed. If the result of the comparison in step 17 and step 20 is outside the allowable value, if the information is being written to preserve the information, the completion is confirmed (step 21) (not shown in FIG. 1), For the safety of the magnetic disk device, if the magnetic head is moving, its completion is confirmed (step 22) (not shown in FIG. 1) and then READY on the interface.
After forcibly turning off the signal to disable access to the magnetic disk device (step 23) (not shown in FIG. 1),
The drive of the SPM is forcibly turned off (step 24), and the LED is forcibly blinked to clearly indicate the occurrence of an abnormality (step 25). After that, when the recording medium 1 is ejected (step 27), what is forcibly carried out in steps 23 to 25 is recovered (steps 28 to 3).
0).

FIG. 4 shows the SPM in one embodiment of the present invention.
It is a diagram showing a configuration of a drive current detection circuit, in the figure,
Reference numeral 31 is a resistor, 32 is an A / D converter, and the SPM drive current detection circuit 8 is composed of 31 and 32. Since the SPM drive current flows through the resistor 31, the voltage V across the resistor 31 is proportional to the SPM drive current. By digitizing this voltage V by the A / D converter, the processing by the microprocessor 11 becomes possible.

The method for detecting an abnormality will be described in detail below. FIG. 5 shows an SPM according to an embodiment of the present invention.
It is a general load torque-current characteristic view of a drive circuit. Here, the SPM drive current changes substantially linearly with the change of the load torque. FIG. 6 is a general track position-necessary torque diagram in an embodiment of the present invention, in which the magnetic head and the recording medium are in a state of being rubbed by being applied with a substantially constant pressure, and the magnetic head. Assuming that the friction coefficient is almost constant with the change of position (track position), the torque required to rotate the recording medium also changes, and the change is almost linearly proportional to the distance from the rotation center to the track position. To do. Therefore, from FIG. 5 and FIG. 6, it can be said that the relationship of the SPM drive current with respect to the track position is almost temporarily proportional.

Next, FIG. 7 is an explanatory diagram of the allowable value setting in one embodiment of the present invention, 33 is the SPM drive current initial measurement value in each track measured in step 15 in FIG. 2, 34 is step 16 Regression line obtained in step 35
Is an upper limit allowable value line, and 36 is a lower limit allowable value line. Here, the regression line 34 is approximated by a straight line because FIGS. 5 and 6 have linear characteristics. Further, the upper limit allowable value line 35 is a value obtained by increasing the regression line 34 by a certain percentage, and the lower limit allowable value line 36 is a value obtained by reducing the regression line 34 by a certain percentage. The abnormality between the magnetic head and the recording medium is detected when the SPM drive current value measured in steps 15 and 19 is not between the upper limit allowable value line 35 and the lower limit allowable value line 36.

Example 2. In the above embodiment, the method of approximating the SPM drive current value is a linear approximation using a regression line. However, in the present invention, the approximation is performed using two lines in consideration of the friction difference between the inner circumference and the outer circumference of the recording medium 1. Anything that can be expressed by simple continuous values, such as approximation with a straight line, may be used. Further, when an abnormality is detected, the READY signal is forcibly turned off and the LED is forcibly blinked, but in the present invention, any means may be used as long as the abnormality is clearly indicated.

[0016]

As described above, according to the present invention, it is possible to detect an abnormality that occurs between the magnetic head and the recording medium, from the amount of change in the drive current of the spindle motor drive circuit. As a result, it is possible to prevent the destruction of the magnetic head or the recording medium from occurring and obtain high reliability.

As a technique related to the present invention, Japanese Patent Application Laid-Open No. 2-244457 discloses a technique of monitoring the current of a drive motor and stopping the drive motor when an abnormal current flows. The present invention is further effective by the following constitution. The present invention is provided with means for measuring the currents of the drive motors in a plurality of tracks before starting the operation of the magnetic disk device, and means for obtaining an allowable value from the measured current values. It is possible to set the allowable value in consideration of the variation of each medium and the track on which the magnetic head is located. Therefore, it is possible to prevent erroneous determination due to the abnormal current being determined by a uniquely determined allowable value, and it is possible to make a fine-tuned determination that is optimal for each individual disk device, recording medium, and track being used. . In addition, when a current out of the allowable value is detected during writing or reading of information, the magnetic disk device is not immediately stopped, but a means for stopping the operation currently being performed is provided so that the information can be preserved. It is possible to prevent the recording medium and the device from being damaged.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a first flowchart in one embodiment of the present invention.

FIG. 3 is a second flowchart according to the embodiment of the present invention.

FIG. 4 is a configuration diagram of an SPM drive current detection circuit according to an embodiment of the present invention.

FIG. 5 is a load torque-current characteristic diagram of the SPM drive circuit according to the embodiment of the present invention.

FIG. 6 is a track position-necessary torque diagram in one embodiment of the present invention.

FIG. 7 is an explanatory diagram of allowable value setting in one embodiment of the present invention.

FIG. 8 is a perspective view of a head support mechanism of a conventional magnetic disk device.

[Explanation of symbols]

1 recording medium 7 SPM drive circuit 8 SPM drive current detection circuit 11 microprocessors 33 SPM drive current initial measurement value 34 regression line 35 upper limit tolerance line 36 Lower limit tolerance line

Claims (2)

[Claims] 1. A magnetic disk device comprising a spindle motor for rotating a recording medium and a measuring means for measuring a drive current of the spindle motor, wherein the measuring means is used for a plurality of tracks on the recording medium before an information read / write operation. Equipped with an approximation means for approximating the measured track-to-driving current characteristic by a simple continuous value, and a tolerance value setting means for setting a tolerance value for the approximated value, and the measurement was performed by the above-mentioned measurement means on the track during the reading / writing operation of information. A magnetic disk device, wherein the drive of the spindle motor is stopped when the drive current exceeds the allowable value. 2. The magnetic disk drive according to claim 1, wherein the drive of the spindle motor is stopped after a read / write operation in progress is completed.