JPH0525088Y2 - - Google Patents

Description

[Detailed description of the invention] [Summary] In a rotary magnetic head positioning mechanism installed to receive torque due to gravity in a fixed direction, the generated torque of a magnetic torque generator used to suppress the variation range of the torque. By configuring it to act in a constant direction opposite to the direction in which the torque due to gravity acts, it is possible to reduce the size and weight.

[Industrial Field of Application] The present invention relates to a magnetic head positioning mechanism, and particularly to a rotary magnetic head positioning mechanism for a horizontal spindle type magnetic disk device.

The magnetic head positioning mechanism is a mechanism used to position the magnetic head on a desired track on the magnetic disk, and is equipped with an access arm that carries the magnetic head at its tip and moves, and a drive motor that drives the access arm. Depending on the method of moving the magnetic head, there are two types: a linear type that moves on a straight line (linear type) and a rotary type that moves on an arc (rotary type).
It is broadly divided into.

On the other hand, magnetic disk drives are broadly classified into vertical spindle types, in which the spindle is vertical, and horizontal spindle types, in which the spindle is horizontal.

Furthermore, positioning control is classified into closed-loop control and open-loop control depending on the method of positioning control, and the former generally uses a voice coil type drive motor, and the latter uses a stepping motor. In any case, in order to improve control accuracy, it is desirable that the load torque and its fluctuations be small.

[Conventional technology]

Fig. 4 is a schematic diagram of a rotary magnetic head positioning mechanism used in a horizontal spindle type magnetic disk device (a is a front view, b is a XX sectional view), and 5 is a diagram showing the horizontal spindle S1. 1 represents a rotating magnetic disk; 1 is an access arm that is equipped with a magnetic head 11 at its tip and is driven about another axis S2 parallel to the main axis S1 of the magnetic disk 5; 2 is an access arm that drives the access arm 1; A rotary voice coil type drive motor is driven, and 3b is a magnetic torque generator that generates torque according to the rotation angle of the access arm 1 using magnetic force.

The voice coil drive motor 2 includes a pair of moving coils 21 that are symmetrically provided with respect to another axis S2,
A rotating body 22 equipped with a pair of moving coils 21 and rotating about another axis S2, and fixed symmetrically about the other axis S2 so as to sandwich the rotating surface of the moving coil 21 (see XX sectional view b). 4 sets of permanent magnets 2
3, and the center of gravity of the rotating body 22 including the moving coil 21 is aligned with another axis S2. Therefore, even if the rotation angle changes, almost no torque is generated due to gravity.

On the other hand, the access arm 1 is asymmetrical with respect to the other axis S2 and is not provided with a counterweight so as not to increase the weight and moment of inertia. Therefore, torque due to gravity is generated depending on the rotation angle.

FIG. 4a shows a state in which the magnetic head 11 is positioned at the center between the innermost track IT and the outermost track OT of the magnetic disk, and the access arm 1 is located between the outermost track OT and the innermost track OT. Move the scope of IT.

Therefore, torque due to gravity acts on the rotating portion of the magnetic head positioning mechanism including the access arm 1 in a counterclockwise direction in FIG. 4a.

This value depends on the inclination of access arm 1.
It changes as shown by the curve Tg' in the figure, and is small when the magnetic head 11 is positioned on the outer track OT side of the magnetic disk, and large when it is positioned on the inner track IT side.

The magnetic torque generator 3b includes a rotor 31 made of a magnetic material that rotates about another axis S2 together with the access arm 1, and a permanent magnet fixed to the outer periphery of the rotating rotor 31 facing each other about another axis S2. In the illustrated state in which the magnetic head 11 is positioned at the center between the innermost track IT and the outermost track OT of the magnetic disk, both poles of the rotor 31 are fixed. Child 3
It is facing 2.

Therefore, the torque due to magnetic force is zero, and the sixth
As shown by the curve Tm' in the figure, the magnetic head 11 moves from this position (neutral position) to the outer track of the magnetic disk.
Moving to the OT side produces a counterclockwise torque that changes exponentially, and moving to the IT side of the inner track produces a clockwise torque that changes in the same way.

Therefore, the load torque of the voice coil type drive motor 2 changes as shown by the curve Tb in FIG. 5, and the fluctuation range of the load torque decreases from B to B'.

[Problem that the invention attempts to solve]

In the conventional example, the magnetic torque generator 3b is used in a range where the generated torque is relatively small around the neutral position.

Therefore, it is necessary to use a large permanent magnet in the stator, which is disadvantageous in terms of cost.

That is, an object of the present invention is to improve the utilization efficiency of permanent magnets used in magnetic torque generators.

[Means for solving problems]

The magnetic head positioning mechanism according to the present invention has a first
As shown in the principle diagram in the figure, the horizontal spindle type magnetic disk device is installed so that it always receives the torque Tg due to gravity in a fixed direction with respect to another axis S2 parallel to the main axis S1. an access arm 1 that is positioned on a track; a rotary voice coil type drive motor 2 that drives the access arm 1; and a torque that corresponds to the rotation angle of the access arm 1.
In a magnetic head positioning mechanism including a magnetic torque generating device 3 that generates Tm, the torque generated by the magnetic torque generating device 3 in response to the torque Tg due to gravity received in the certain direction.
It is constructed so that Tm always acts in the opposite direction.

[Effect]

A magnetic torque generator is configured so that one of the stator and rotor is a magnet and the other is a magnetic body, and torque is generated by the magnetic force between the magnet and the magnetic body. The generated torque
Tm is zero when the rotor poles are facing the stator, and increases exponentially as the rotor moves away from this state (neutral position).

Therefore, in the conventional example, the magnetic torque generator is used in an area where the torque increase rate is small near its neutral position, so the maximum width of the usable torque Tm is ΔT' (see Figure 5). Not very accurate.

In contrast, in the present invention, even if the magnetic torque generator has the same shape, dimensions, and materials as the conventional example, it uses a region where the rate of change in torque is large, so the maximum width of the usable torque Tm is 2), it can be made larger than the conventional example.

〔Example〕

FIG. 3 shows an embodiment in a plan view.

This is applied to a device in which the number of magnetic disks is increased compared to the conventional example, and the number of access arms is doubled accordingly, and the torque acting on the rotating part of the magnetic head positioning mechanism due to gravity is , which is approximately twice that of the conventional example.

The same reference numerals as in FIGS. 1 and 4 refer to the same objects, and in FIG. 4 (conventional example), the magnetic head 11 is located at the center of the innermost track IT and the outermost track OT of the magnetic disk 5. In contrast, in FIG. 3, the magnetic head 11
is positioned at the outermost track of the magnetic disk. In this state, the magnetic torque generator 3 is in the neutral position, the magnetic head 11 moves toward the inner track IT side of the magnetic disk, and the magnetic torque generator 3 is positioned at the outermost track IT of the magnetic disk. The torque generator 3 generates a clockwise torque that increases as indicated by Tm in the figure.

On the other hand, torque due to gravity always acts counterclockwise on the rotating part including the access arm 1, and as the magnetic head 11 moves toward the inner circumferential track IT side of the magnetic disk, the torque increases as shown in the figure Tg.

Therefore, the load torque of the voice coil type drive motor 2 changes as shown by the curve Ta, and the fluctuation range of the load torque decreases from A to A' due to the action of the magnetic torque generator 3.

In this embodiment, the number of magnetic disks is reduced to about 2 compared to the conventional example.
Although this is applied to a device that has doubled in number, if the number of magnetic disks is the same as in the conventional example, the shape, weight, and material of the magnetic torque generator 3 can be reduced.

[Effect of idea]

As described above, the magnetic head positioning mechanism according to the present invention can reduce the size and weight of a magnetic disk device and reduce costs.

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is an explanatory diagram of the operation, Fig. 3 is a configuration diagram of the embodiment, Fig. 4 is an explanatory diagram of the conventional example, and Fig. 5 is an explanatory diagram of the conventional example. . In the figure, 1 is an access arm, 11 is a magnetic head, 2 is a voice coil drive motor, 3 and 3b are magnetic torque generators, 31 is a rotor, and 32 is a stator.

Claims (1)

[Scope of Claim for Utility Model Registration] A horizontal spindle type magnetic disk device is provided so as to receive a torque Tg due to gravity in a certain direction with respect to another axis S2 parallel to the main axis S1, and a magnetic head to be mounted is placed on the track of the magnetic disk. A magnetic head positioning mechanism comprising an access arm 1 for positioning, a rotary voice coil drive motor 2 for driving the access arm 1, and a magnetic torque generator 3 for generating torque according to the rotation angle of the access arm 1. In, the torque generated by the magnetic torque generator 3 with respect to the torque Tg due to gravity received in the certain direction.
A magnetic head positioning device characterized in that it is configured such that Tm always acts in the opposite direction.