JPH04126361U - Positioning mechanism of hard disk drive device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a mechanism that enables high-speed, high-precision positioning of even high-density, large-capacity magnetic recording media by adopting a two-stage servo system with two movable parts in a hard disk drive device. The purpose is to [Structure] Consisting of a first movable part with a magnetic head attached to an actuator arm, and a second movable part mechanically connected to the first movable part, the second movable part is displaced using a motor as a drive source. The first movable part is a mechanism for causing minute displacement using a piezoelectric element provided in the connecting part as a driving source.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to a positioning mechanism in a hard disk drive device. This provides a device that performs high-speed, high-precision positioning.

0002

[Conventional technology]

The positioning mechanism is controlled using servo information formed on the magnetic disk surface, and the head In the closed-loop control method for positioning the Since then, a number of methods have been adopted. Among the methods, it is easier In order to have a compact structure and miniaturize the device, a voice coil motor is used to reduce the radius. A rotary actuator whose magnetic head swings in the direction to access the target servo area. Eta is suitable.

0003 The actuator is connected to the voice coil motor drive control loop as shown in Figure 4. Therefore, it is driven. When instructed to move to the target truck, the voice coil module The motor performs speed control. Then, when the target track is reached, it switches to position control. , overshoot (when the magnetic head does not stop accurately on the target track and goes too far) ), the direction and amount of current flowing through the coil of the voice coil motor. When the head converges on the target track by changing the ON track (positioning complete).

0004

[Problems with conventional technology]

However, if a rotary actuator is used in the closed-loop control method, As mentioned above, the simple structure and miniaturization of the device can be achieved, but the high speed and high This has the disadvantage that accurate positioning is difficult.

[0005] In order to solve the above problem, the magnetic head is set to the target track at the start of the speed control operation. When you are further away, increase the speed to shorten the travel time and track the target. When approaching the target, decelerate sufficiently, and when switching to position control, overshoot It was necessary to make it as short as possible.

[0006] Therefore, in speed control, we have traditionally created an ideal speed curve (relationship between position and speed) in advance. is created in advance, and the moving speed of the magnetic head is controlled along the curve to create an overshoot. Methods have been used to shorten the distance between

[0007] However, simply shortening the overshoot using the above method is insufficient for high-density, As large-capacity magnetic recording media become available, magnetic head High-speed, high-precision positioning of the voice coil motor is difficult. There were limits to position control using flow alone.

[0008] In other words, as mentioned above, when the damped vibration of the actuator occurs and the vibration amplitude is large, As mentioned above, the voice coil motor provides sufficient position control, but vibrations gradually occur. As the width becomes smaller, the voice coil motor, which is a coarse motor, requires position control. It was difficult to do this, and it took a considerable amount of time to complete the positioning.

[0009] Therefore, in order to solve the above problem, two movable parts are used during position control. If the distance of the bar shot is far away from the target track, the conventional action will be applied. Positioning is performed centering on the voice coil motor installed in the tuator. 2 movable part), and another movable part (1st movable part) connected to the second movable part as the vibration width becomes smaller. A so-called two-stage servo system was proposed in which positioning is performed using a movable part as the center.

0010 The above-mentioned two-stage servo system is well known, and one example is Japanese Patent Application Laid-Open No. 59-21507. 9 can be given. This idea was developed using an optical pick-up as a tracking drive method for optical disk drives. The coarse motor that drives the entire top and the actuator that drives the objective lens are complementary to each other. By configuring the laser beam to follow the track by driving the This method allows the spot to be positioned in the guide groove on the disk medium at high speed and with high precision. .

[0011] However, the two-stage servo system of rotary actuators is still in its infancy. There is no example of it being used in a hard disk drive device, and in order to use it, a second movable part is required. A drive source that increases the load inertia to the drive source, or increases the resonance point in the low frequency range. If you select a drive source for the first movable part like this, it will not only hinder high-precision positioning, but also There was a problem that the device could not achieve the purpose of high-speed access.

0012 This invention was devised in view of the above-mentioned actual situation. The positioning of the magnetic head of the disc drive device is performed using only the voice coil motor, which is a coarse motor. The settling time (the rotor's damped vibration The seek time is reduced by shortening the time it takes to stop at the target position while Provides a mechanism that enables high-speed, high-precision positioning even on high-density, large-capacity magnetic recording media The purpose is to

[0013]

[Means to solve the problem]

In order to achieve the above purpose, this invention has a magnetic head attached to the actuator arm. It consists of a first movable part that is attached to the vehicle, and a second movable part that is mechanically connected to the first movable part. The second movable part is displaced using the motor as a drive source, and the first movable part is displaced by the connecting part. The structure is such that a piezoelectric element provided in the structure is used as a driving source to cause minute displacement.

[0014]

[Effect]

When commanded to move to the target track, the voice coil motor controls the speed. When the target track is reached, the magnetic head switches to position control operation and the magnetic head starts damping vibration. The vehicle converges on the target track while moving, but the vibration amplitude during the damped vibration is large. The position control is performed mainly by the voice coil motor, which is the coarse motor of the first moving part. The piezoelectric element, which is the second movable part, is suitable for minute vibrations as the vibration width becomes smaller. The settling time is reduced by a two-stage servo system that performs position control using minute feeds centered on is shortened.

[0015]

【Example】

Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows the first part of this invention. FIG. 1 is a schematic diagram of a rotary actuator showing an example. 1 is a rotary type actuator, and the voice attached to the carriage 3 It forms a movable part that rotates around a rotating shaft 9 by a coil motor 6 (second movable part). moving parts). Therefore, depending on the direction of the current flowing through the coil 6a of the voice coil motor 6, The structure is such that the direction of rotation of the rotary actuator 1 can be changed. ing. 4 is an actuator arm, and a magnetic head 5 is provided at the tip. The actuator arm 4 is attached to the carriage 3 via the hinge 2. There is.

[0016] 8 is a laminated piezoelectric element. In the embodiment of this invention, a laminated type is used as the piezoelectric element. However, it does not necessarily have to be a laminated type, and it is possible to use microscopic structures such as bimorph due to the electrostrictive effect. Anything that can be displaced can be used.

[0017] One end of the piezoelectric element 8 is connected to one side 3a of the carriage 3, and the other end (the tip in the stacking direction) is installed on the hinge 2a. On the other hand, the other side 3b of the carriage 3 (where the piezoelectric element 8 is attached) The hole 2b' of the hinge 2b is inserted into the convex part 3b on the side opposite to the side 3a where the hinge 2b is attached. is inserted to form the fulcrum part 7.

[0018] Therefore, the rotary type actuator 1 responds to minute displacements of the piezoelectric element 8. , the actuator arm 4 rotates minutely around the fulcrum 7 due to lever action. (first movable part), and by turning on and off the current flowing through the piezoelectric element 8, It is possible to minutely feed the head by changing the direction of rotation as appropriate. In addition, the second movable part By installing piezoelectric elements 8 on both sides 3a and 3b of the carriage 3, It is also possible to have a structure in which it is sent.

[0019] FIG. 2 is a diagram showing the relationship between the driving speed v of the voice coil motor 6 and the time t. . The magnetic head evacuated to the park area C (non-data area) of the magnetic recording medium 10 Head 5 sends a positioning finger from the host computer to the target track in data area D. As a result, a constant current is applied to the coil 6a of the voice coil motor 6, and the first actuation is activated. The rotary actuator 1, which is a rotary actuator, is rotated to pass through the target track. Perform appropriate speed control operations until the

[0020] Specifically, as shown in FIG. 2, a constant current is applied to the coil 6a of the voice coil motor 6. By giving time Ta in the direction, the rotary actuator 1 moves toward the target during that time. Make an acceleration movement towards the truck. When a sufficient speed Va is reached, the voice control The current flowing through the coil 6a of the coil motor 6 is stopped and the motor is allowed to move at a constant velocity for a time Tb, and then When the magnetic head 5 approaches the target position, the coil of the voice coil motor 6 A current in the opposite direction to the above-mentioned current is applied to the coil 6a to start deceleration motion, and the voice coil motor When the driving speed of the motor 6 becomes 0 (point x), the speed control operation ends and the target track is Switch to position control operation to compensate for the passage of Approach the rack and turn on track. At the end of this speed control range, An ideal speed curve (position and speed) should be created in advance to shorten the overshoot distance. relationship) is stored in the CPU (not shown), and the magnetic head Minimize the overshoot distance by controlling the movement speed of the It has become so.

[0021] According to the present invention, damped vibration is Sometimes, when the target track is far away from the target track, the second movable part, which is a coarse motor, While the positioning process is performed mainly using the mounted voice coil motor, the vibration width is reduced. The so-called two-stage process, in which positioning is performed centering on the first movable part, is used to reduce slight vibrations. It uses a servo system.

[0022] Furthermore, the piezoelectric element is used as the drive source for the first movable part. The piezoelectric element itself is lightweight and has almost no effect on the load inertia of the first moving part. stomach The self-resonant frequency is high, and the response of displacement and generated force is fast from 0N to 0FF of the applied voltage. follow with Since no magnetic noise is generated, it does not affect other peripheral circuits and equipment as the first moving part. nothing to give Due to the reason.

[0023] Next, the two-stage servo system will be explained in comparison with the present invention. Figure 3 shows the two-stage servo system. FIG. The method described above uses the inertia of the voice coil motor 6, which is a coarse motor. Because the interference caused by the reaction that the first moving part receives from destabilizes the control system. , to the coil 6a of the voice coil motor 6 of the first movable part in order to correct the inertial force. The inertial force is predicted from the applied current, and a current proportional to the inertial force is applied to the piezoelectric element 8 as appropriate. This is a control method that increases the

[0024] In the figure, (g) is a comparator, (a) is a position error detection circuit, (b) is a phase compensation circuit, (c) is a coupling compensation circuit, (d) is a drive circuit for the second movable part, and (e) is the first movable part. (f) is the adder.

[0025] First, the target value α to the target track is determined according to the instruction of the positioning signal. The target value α is input to the position error detection circuit (a) via the comparator (g) and is detected by this circuit. After the relative position signal between the target track and the magnetic head is detected, the phase compensation circuit (b ) to adjust the error signal.

[0026] Since the magnetic head described above performs a damping motion, the distance between the target track and the target track is greatly increased. (when the position error signal mentioned above is large), the voice coil mode suitable for coarse movement is activated. Since most of the drive signals are transmitted in the direction of arrow A, the coupling compensation circuit The signal is input to the drive circuit (d) of the second movable part via (c), and the voice coil motor The magnetic head is roughened in the radial direction by appropriately changing the amount and direction of the current flowing through the coil 6a. make it move. On the other hand, when the damped vibration starts, almost no drive signal is transmitted in the direction of arrow B. Therefore, the piezoelectric element installed in the first movable part is hardly displaced. And Canada After the sum of the displacement signal of the second movable part and the displacement signal of the first movable part is added in calculator (f), The comparator (g) compares the feedback with the target position, and when the target value is reached. If not, repeat the same operation as above.

[0027] As the magnetic head undergoes damped vibration and approaches the target position, the vibration amplitude becomes smaller. Therefore, the proportion of the signal transmitted in the direction of arrow A is decreased, and the proportion of the signal transmitted in the direction of arrow B is decreased. Position control is achieved by increasing the proportion of the signal to be used and driving a piezoelectric element suitable for micro-drive. Repeat as described above. When the value of the comparator (g) becomes 0, the position control operation is This completes the head positioning.

[0028] Note that this example describes positioning using a rotary type actuator. However, it goes without saying that the present invention can also be applied to linear actuators. Nor.

[0029]

[Effect of the idea]

According to the present invention, positioning is performed while performing damped vibration using position control as described above. When the vibration width of the device is large, the voice coil motor, which is the drive source of the second movable part, The drive source of the first movable part is controlled as the vibration amplitude becomes smaller. The hardware uses a two-stage servo system that performs position control using a piezoelectric element that is suitable for small vibrations. By adopting it in disk drive equipment, it can replace the voice coil motor, which is a conventional coarse motor. It takes less time to reach the target track compared to a device that converges damped vibration using only a motor. This greatly reduces the time required for high-speed, high-precision heads for high-density, large-capacity magnetic recording media. Can be positioned.

[Brief explanation of drawings]

[Fig. 1] Schematic diagram of a rotary type actuator that is an embodiment of the present invention

[Fig. 2] A diagram showing the relationship between the driving speed v of the voice coil motor 6 and the time t.

[Figure 3] Block diagram of two-stage servo system

[Figure 4] Voice coil motor drive control loop

[Explanation of symbols]

1 Rotary type actuator 5 Magnetic head 6 Voice coil motor 8 Piezoelectric element

Claims (1)

[Scope of utility model registration request] 1. A hard disk drive device that reads and writes information on a magnetic disk surface by accessing an arm to which a magnetic head is attached, comprising: a first movable part having a magnetic head attached to the arm; and a second movable part mechanically connected to the first movable part, the second movable part is displaced using a motor as a drive source, and the first movable part is displaced using a piezoelectric element provided in the connecting part as a drive source. A positioning mechanism for a hard disk drive device, characterized in that it is configured to be displaced.