JPH1092136A - Slider mechanism for magnetic disc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slider mechanism for a magnetic disc which does not generate a head crush phenomena in which a head slider is stuck to a magnetic disc and cannot float. SOLUTION: A current sensor 2 for detecting a drive current, an actuator fixing section 1k fixed to a swing arm 14, an actuator movable section 1m fixed to a gimbal spring base plate 13p and a control circuit 3a for controlling the actuator movable section 1m by receiving a signal of current sensor 2 are provided between the spindle motor 51m of HDD body 51 and the drive circuit 51k. When the signal of current sensor 2 having correlation with the number of rotations of the magnetic disc 11 does not satisfy the specified value, a pushing force of the head slider 12 is reduced by locating the actuator movable section 1m to the upper position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slider mechanism for a magnetic disk used in a hard disk drive or the like.

[0002]

2. Description of the Related Art The principle of operation of a head slider for a magnetic disk is shown in FIG. The main components are a magnetic disk 11, a head slider 12, and a gimbal spring 13, and a head slider is attached to a swing arm 14 connected to a drive mechanism (not shown) for controlling the position of the head slider 12 in the radial direction on the magnetic disk 11. 12 is held via a gimbal spring 13. The head slider 12 is a gimbal spring 13
Is pressed against the magnetic disk 11 by
When the magnetic disk 11 is stationary, the head slider 12 is in contact with the magnetic disk 11. When the magnetic disk 11 starts rotating while contacting the head slider 12 in the direction D, air 99 on the magnetic disk 11 flows into the flying surface 12a of the head slider 12, and the head slider 12 is moved from the magnetic disk 11 to a submicron by the dynamic pressure effect. The magnetic disk 11 is floated in the flying gap H of the order, and the magnetic disk 11 is written and read. And
When the magnetic disk 11 stops, the dynamic pressure effect disappears, and the head slider 12 comes into contact with the magnetic disk 11 again and stops.

[0003]

In the above-described example, the magnetic disk keeps rubbing with the head slider during the low rotational speed when the dynamic pressure effect at the time of starting and stopping the rotation of the magnetic disk is insufficient. As a result, the contact surface is smoothed, and in the worst case, a phenomenon called a head crash in which the head slider cannot be floated by being attracted to the magnetic disk sometimes occurs.

An object of the present invention is to provide a magnetic disk slider mechanism that does not cause head crash.

[0005]

According to the present invention, there is provided a magnetic disk which comprises a head slider, a gimbal spring in which a load beam supporting the head slider and a base plate fixed to a swing arm are integrated. And a state sensor for detecting the rotation state of the magnetic disk or the contact state between the head slider and the magnetic disk, and a pressing load on the head slider. And a circuit for controlling the actuator by comparing a signal from the state sensor with a specified value. When the signal from the state sensor does not satisfy the specified value, the actuator applies a pressing load to the head slider. Decrease
When the specified value is satisfied, the pressing load on the head slider is increased.

According to a second aspect of the present invention, in the magnetic disk slider mechanism according to the first aspect, the state sensor is a current sensor for detecting a drive current of the motor. According to a third aspect of the present invention, in the magnetic disk slider mechanism according to the first aspect, the state sensor detects an elastic vibration caused by contact between the magnetic disk and the head slider.
(acoustic emission) sensor.

According to a fourth aspect of the present invention, in the magnetic disk slider mechanism according to the first aspect, the state sensor is a frictional force sensor for detecting a frictional force of the head slider with the magnetic disk. The invention according to claim 5 is the invention according to claim 4.
In the slider mechanism for a magnetic disk described in (1), the frictional force sensor is a distortion sensor that detects the frictional force of the head slider as beam distortion.

According to a sixth aspect of the present invention, in the magnetic disk slider mechanism according to any one of the first to fifth aspects, the actuator moves the base plate of the gimbal spring in a direction perpendicular to the surface of the magnetic disk. This is a drive mechanism that changes the load on the head slider by changing the distance from the disk. According to a seventh aspect of the present invention, in the slider mechanism for a magnetic disk according to the sixth aspect, the drive mechanism is configured by a micro solenoid and a spring, or a micro motor and a ball screw or a ball bearing.

According to an eighth aspect of the present invention, in the magnetic disk slider mechanism according to any one of the first to fifth aspects, the actuator is a shape memory alloy bonded to the base plate of the gimbal spring and the load beam. The shape memory alloy has a structure in which a pressing load on a head slider is changed by a change in shape according to a signal of a control circuit.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a magnetic disk slider mechanism, comprising: a state sensor for detecting a rotation state of a magnetic disk or a contact state between a head slider and a magnetic disk; and an actuator for changing a pressing load on the head slider. And a circuit for controlling the pressing load on the head slider by a signal from the state sensor to control the pressing load on the head slider.

[0011]

【Example】

Embodiment 1 FIG. 1 shows an embodiment of the present invention. The magnetic disk 11 is fixed to a shaft of a spindle motor 51m incorporated in an HDD (abbreviation of hard disk drive) main body 51, and the number of revolutions is controlled by a drive circuit 51k.
The head slider 12 has a gimbal spring load beam 13b.
Gimbal spring base plate 1
3p is fixed to the actuator movable part 1m. Further, an actuator fixing portion 1k is fixed to a swing arm 14 connected to a drive mechanism (not shown) for controlling the position of the head slider 12 on the magnetic disk 11 in the radial direction.

A current sensor 2 for detecting a drive current, for example, abbreviated as CT, is provided on a wiring between the drive circuit 51k and the spindle motor 51m, and a signal from this sensor is input to a control circuit 3a for controlling the actuator movable section 1m. Is done. The drive current characteristic of the spindle motor 51m, which is a DC motor, is maximum when the magnetic disk 11 is not rotating, and decreases as the number of rotations increases. Control circuit 3a
Compares the reference value with the drive current value, and if the drive current value is large, the actuator movable section 1m is positioned at the upper limit of the actuator, and if the drive current value is small, it is positioned at the lower limit of the actuator. That is, the head slider 12 is separated from the magnetic disk 11 when the rotation speed is low, and the head slider 12 is pressed in the direction of the magnetic disk 11 with a constant load as indicated by a broken line when the rotation speed is high.

In this embodiment, the operating range of the actuator movable portion 1m is wide. If the movable range is narrow, the reduction in the number of revolutions only reduces the pressing load on the head slider 12, and as shown below, 12 does not leave the magnetic disk 11. FIG. 2 is a characteristic diagram of each variable when the operation range of the actuator movable section is narrow. As shown in the figure, the vertical axis represents the rotation speed of the magnetic disk, the drive current of the spindle motor, the pressing load of the head slider, and the flying height of the head slider, from the top, and the horizontal axis represents time t. The rotation speed increases from t0 to reach the maximum rotation speed at tp1, and after maintaining the constant rotation speed until tp2, decreases and stops at tp3. The drive current is maximum at times t0 and tp3 when the motor is not rotating, and is minimum between tp1 and tp2. It is a reference value of the drive current, and the times ti1 and ti
2 shows that the drive current coincided with the reference value.

Further, the pressing load of the head slider is:
Since the drive current is larger than the reference value from t0 to ti1, the actuator movable part is separated from the magnetic disk and the load is low as w1, but the drive current becomes smaller than the reference value at ti1 and the actuator movable part becomes smaller than the reference value. And the load increases to w2. Then, at ti2, the driving current becomes larger than the reference value again, so that the load becomes low as w1.

The broken line of the curve representing the flying height of the head slider is the characteristic of the conventional method shown for reference. Here, ht indicates the surface roughness value of the magnetic disk. If the flying height of the head slider is smaller than this, it means that the head slider is in contact with the magnetic disk. According to the present invention, the load of w2 is applied only from ti1 to ti2, and the load becomes w1 otherwise.
Between ti1 and ti2 to tp3, the flying height is larger than when w2 is added, and when the load becomes w2, the flying height becomes the same as that of the conventional method. Therefore, the contact time of the head slider with the magnetic disk is th3 and th4.
This is a great improvement over the conventional th1 and th2.

Embodiment 2 FIG. 3 shows another embodiment of the present invention. This example is different from the current sensor 2 in FIG. 1 only in that an AE sensor 4 for detecting elastic vibration caused by contact between the head slider 12 and the magnetic disk 11 is fixed to the actuator movable portion 1m. Description is omitted because it is the same as 1. The control circuit 3b receives the signal from the AE sensor 4 and controls the actuator movable section 1m. FIG. 4 shows the rotation speed of the magnetic disk 11 which is a characteristic of this embodiment,
This is the relationship between the flying height of the head slider 12 and the effective value of the AE sensor whose time is t. That is,
When the rotation speed is lower than Pt, the effective value of the AE sensor signal is large due to friction between the head slider and the magnetic disk,
When the head slider flies at a high rotational speed of Pt or more, the effective value of the AE sensor signal decreases. Here, the reference value of the control circuit 3b is set to At slightly larger than the AE level at the time of ascent.
, The same operation as in FIG. 2 can be realized.

Embodiment 3 FIG. 5 shows another embodiment of the present invention.
(a) is a plan view and (b) is a side view. 3 is different from FIG. 3 in that a frictional force sensor 5 using a strain gauge 5a is provided instead of the AE sensor 4, and the other parts are the same as those in FIG. In this example, a strain gauge 5a is attached to the cantilever of the frictional force sensor 5 between the gimbal spring base plate 13p and the actuator movable part 1m, and the force in the longitudinal direction of the head slider generated by the rotation of the magnetic disk 11 is distorted. The friction force is detected by the gauge 5a. FIG. 6 shows the relationship between the frictional force and the number of rotations and the flying height, and the frictional force characteristics with time being t. As in the case of FIG.
The frictional force is large when the magnetic disk 11 is in contact with the magnetic disk 11, and is small when the magnetic disk 11 is not in contact. Therefore, when the reference value of the control circuit 3c is set to Mt slightly larger than the frictional force at the time of flying, the same operation as in FIG. 2 can be realized.

Embodiment 4 FIGS. 7 and 8 show FIGS.
It is a specific example for realizing the actuator of FIG. FIG. 7 shows a micro solenoid 1s as an actuator fixing portion 1k,
The gimbal spring base plate 1 is constituted by a guide 1g or the like, and uses the function of the spring 1b to make the movement of the micro solenoid 1s the movement of the actuator movable part 1m in the V direction.
Tell 3p. FIG. 8 shows a configuration in which a micromotor 1d, a guide 1g, and the like are used as the actuator fixing unit 1k, and the ball screw 1n is rotated by the micromotor 1d to move the actuator movable unit 1m in the V direction to move the gimbal spring base plate 13p.

Embodiment 5 FIG. 9 shows another embodiment of the present invention. The difference from FIG. 3 is that the shape memory alloy 6 is joined to the gimbal spring base plate 13p and the gimbal spring load beam 13b instead of the actuator fixing part 1k and the actuator movable part 1m. Abbreviate. In this example, the shape memory alloy 6 is deformed together with the gimbal spring load beam 13b by the signal of the control circuit 3d to change the pressing load on the head slider 12.

[0020]

According to the present invention, the following effects can be obtained. 1) A state sensor for signaling the contact relationship between the head slider and the magnetic disk, an actuator for holding down the gimbal spring load beam to which the head slider is connected, and a circuit for controlling the actuator are provided to start and stop the rotation of the magnetic disk. By reducing the contact time with the head slider, the occurrence of head crash is suppressed because sharp changes in the shape of the contact surface due to scraping of minute projections on the contact surface, generation of wear powder, and temperature rise due to friction are drastically reduced. Further, even if the abrasion powder and dust entering from outside adhere to the contact portion, the flying time of the head slider is long, and the inclination of the air inflow of the head slider at a low rotation speed becomes large, so that the attached matter is easily peeled off and accumulated. Thus, a slider mechanism for a magnetic disk that has improved durability because it is not performed can be provided. (1) Since the drive current of the magnetic disk motor is correlated with the contact state, an inexpensive magnetic disk slider mechanism can be provided by forming the state sensor with a conventionally used current sensor. Can be provided. (Claims 2, 6, 7,
8) 3) Since the AE sensor for detecting the contact state is used, a magnetic disk slider mechanism having a simple structure can be provided. (Claims 3, 6, 7, and 8) 4) Since the frictional force sensor for detecting the contact state is used, a small magnetic disk slider mechanism that does not become thick in the same direction as the rotation axis of the magnetic disk can be provided. (Claims 4, 5, 6, 7, 8) 5) Since a beam and a strain sensor are used as the friction force sensor,
It is possible to provide a magnetic disk slider mechanism capable of realizing the fourth aspect. (Claims 5, 6, 7, 8) 6) Since the movable range of the actuator can be increased,
It is possible to provide a slider mechanism for a magnetic disk that can further enhance the effect of item 1). (Claims 6 and 7) 7) Since the example of the actuator is specified, a slider mechanism for a magnetic disk capable of realizing claim 6 can be provided.
(Claim 7) 8) Since the shape memory alloy is used as the actuator for deforming the gimbal spring, it is possible to provide a magnetic disk slider mechanism having a simple structure and the same dimensions as the conventional one. (Claim 8)

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a graph showing a variation characteristic of FIG. 1 according to the present invention;

FIG. 3 is a configuration diagram of a second embodiment of the present invention.

FIG. 4 is a characteristic diagram of FIG. 3 of the present invention.

5A and 5B are configuration diagrams of a third embodiment of the present invention, wherein FIG. 5A is a plan view and FIG. 5B is a side view.

6 is a characteristic diagram of FIG. 5 of the present invention.

FIG. 7 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 8 is another configuration diagram of Embodiment 4 of the present invention.

FIG. 9 is a configuration diagram of a fifth embodiment of the present invention.

FIG. 10 is an operation principle diagram of a conventional example.

[Explanation of symbols]

 1b Spring 1d Micromotor 1k Actuator fixed part 1m Actuator movable part 1n Ball screw 1s Micro solenoid 2 Current sensor 3a Control circuit 4 AE sensor 5 Friction force sensor 5a Strain gauge 6 Shape memory alloy 11 Magnetic disk 12 Head slider 13 Gimbal spring 14 Swing arm 51 HDD body

Claims (8)

[Claims] A gimbal spring integrally formed with a head slider, a load beam supporting the head slider, and a base plate fixed to a swing arm, wherein the head slider is pressed against a stationary magnetic disk to rotate the magnetic disk by a motor. A magnetic disk slider mechanism for lifting the head slider, a state sensor for detecting a rotating state of the magnetic disk or a contact state between the head slider and the magnetic disk, an actuator for changing a pressing load on the head slider, and a state sensor. And a circuit for controlling the actuator by comparing a signal from the actuator with a specified value.When the signal from the state sensor does not satisfy the specified value, the actuator reduces the pressing load on the head slider to satisfy the specified value. To the head slider when A slider mechanism for a magnetic disk, characterized in that to increase and with load. 2. The magnetic disk slider mechanism according to claim 1, wherein the state sensor is a current sensor for detecting a drive current of the motor. 3. The slider mechanism for a magnetic disk according to claim 1, wherein the state sensor is an AE sensor that detects elastic vibration caused by contact between the magnetic disk and a head slider. . 4. The slider mechanism for a magnetic disk according to claim 1, wherein the state sensor is a frictional force sensor for detecting a frictional force of the head slider with the magnetic disk. 5. The slider mechanism for a magnetic disk according to claim 4, wherein the frictional force sensor is a distortion sensor for detecting a frictional force of the head slider as beam distortion. 6. The magnetic disk slider mechanism according to claim 1, wherein the actuator moves the base plate of the gimbal spring in a direction perpendicular to the magnetic disk surface to change the distance from the magnetic disk. A magnetic disk slider mechanism, which is a drive mechanism that changes a pressing load on a head slider. 7. The slider mechanism for a magnetic disk according to claim 6, wherein the drive mechanism comprises a micro solenoid and a spring, or a micro motor and a ball screw or a ball bearing. 8. The magnetic disk slider mechanism according to claim 1, wherein the actuator is a shape memory alloy joined to a base plate of a gimbal spring and a load beam, and the shape memory alloy is a control memory. A slider mechanism for a magnetic disk, wherein a pressing load on a head slider is changed by a shape change by a circuit signal.