JPS58100277A - Actuator for driving head of magnetic disk device - Google Patents

Abstract

PURPOSE:To minimize the influence of variations exerted on the arm to the head with a simple constitution and, at the same time, reduce the weight of the arm, by using a hollow rotary arm for an actuator, and by installing a driving coil near a head fitting part. CONSTITUTION:A rotary arm 12 of an actuator which revolves around a shaft 11 is made hollow, and a coil 14 forming a magnetic circuit for driving the arm 12 is installed near the head fitting part 13. The driving force of the arm 12 acts on the front end of the arm 12. Therefore, the equivalent mass can be reduced when compared with the case where the coil is installed to the rear end part, and, as a result, the weight of the arm is reduced by using a hollow arm. Moreover, with this simple constitution, the point of force approaches the head and influences of the vibration on the arm to the head is reduced even when the length of the arm 12 is increased. Therefore, a head driving actuator which is operated at a high speed with high accuracy is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION +II Technical Field of the Invention The invention relates to an actuator for driving a magnetic disk drive head/write head.

Especially regarding rotary actuators◇
, <21 Background of the Technology 5.15. Information to be contained - increase in enemy numbers,
``With the diversification of used systems and functions, there is a demand for faster information processing and higher density of magnetic disks that store information. In order to achieve such high speed and high density storage of magnetic disks, when accessing the head with magnetic disk sat.

The head must be able to move at lightning speed and stop suddenly at a precise position. At present, mechanical vibrations of the actuator of the l-head drive phase are a major obstacle to obtaining such a high-speed drive head that can suddenly stop and accelerate.

(3) Conventional technology and problems ゛Conventional head drive actuators include a linear type and a rotary type (swing arm type), and the rotary type has a smaller 2-equivalent mass than the linear type, making the entire device compact. However, the mechanical vibration of the arm that supports the head was often a problem, and there was a certain limit to how high the speed could be increased.・ □Figure 1 is a top view of a conventional rotary actuator. A head 3 is fixed to the side surface of the tip of an arm 2 that moves entirely over a magnetic disk 5 in the direction of an arrow A around a rotating shaft 1. A coil 4 for configuring an arm driving magnetic circuit (not shown) is provided at the rear end of the arm 2. Therefore, the force F that moves the arm 2 acts on the rear end of the arm 2 as shown. Assuming that the moment of inertia of 1 radii of rotation center of this actuator is t-I, this is the movement of this thread. However, 'I; is the acceleration, B is the magnetic flux density, l is the coil length, and i is the current. In order to increase the total speed of the actuator's motion, m-=2 (23), it is necessary to reduce the mass m or increase the force Fk.However, increasing the force Ff means an increase in the force, This is undesirable in terms of increasing the size of the magnetic circuit (thus increasing the number of heavy stitches) or increasing the amount of heat generated by the coil. is obtained, and if the same resistance coil is used, the amount of heat generated (power consumption Q) is proportional to 1 equivalent lx the square of the lid. Therefore.

By reducing the equal image quality tm, power consumption can be reduced and actuator speed can be increased. This equal image quality tm is expressed by equations (1) and (2). In other words, in order to reduce the first image quality 1tm, it is sufficient to increase r and/or R1t, but as the arm becomes longer, the distance between the head and the drive unit (the point of application of force F) increases, and the vibration generated between them increases. If the number increases, the negative impact on the head will increase. Furthermore, even if +rk is increased, the compensation moment I also increases, so the equivalent *tmμ does not decrease much. Another drawback is that the azimuth angle (inclination with respect to the tangential direction) of the head becomes large because the arm cannot be fully lengthened due to vibration. Furthermore, when the head and the drive unit are arranged with a large distance (4), the head position ti11'I
! - When performing feedback control of the position of the head using the drive unit, vibration on the arm has an adverse effect, making it impossible to perform highly accurate feedback positioning control. Also, for actuators with multiple head systems.

In order to cope with vibrations, arms are formed corresponding to each head, and each arm is stacked to form one arm assembly. For this reason, the weight of the arm was large.

(4) Purpose of the Invention The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it uses a simple structure to reduce the influence of the arm on the arm on the head.

The purpose of the present invention is to provide a head IIA actuator that is capable of high-precision and high-speed operation.

(5) Structure of the Invention In order to achieve all of the above objects, the present invention has a plurality of heads on the side of the rotating arm, and the 11jA working magnetic circuit of the arm is
6. Installed on the rotating arm of the coil assembly to configure the
c In the actuator for driving the head of a magnetic disk drive, the rotary arm of the H-pi? It is constructed as an integral piece with a central nut shape, and the coil is provided near the head mounting position of the rotating arm.

(6) Embodiment of the Invention FIG. 2 is a top view of an actuator according to the present invention for explaining the details of the invention. Arrow A at the center of rotation axis 1
A head 3 is fixed to the side surface of the tip of an arm 2 that moves over a magnetic disk 5 as shown in FIG. The sword F' that drives this arm 2 is made to act on the tip of the arm 2 as shown. If the equal image mass of this actuator is m', m'=□ (6) R can be obtained in the same manner as the calculation procedure described above. That is, m'/m = r/E, and it is possible to reduce the uniform image mass compared to conventional actuators. Furthermore, since the point of action of the head and the sword are close to each other, even if the arm is lengthened, the shadow 41 of the photographing on the arm on the head is small.

FIG. 3 is a perspective view of the inventive actuator.

A plurality of heads 13 are fixed to the side of the distal end of the arm 12. is provided with a short coil type coil 14 for configuring a magnetic circuit (described later) for driving this arm.A magnetic disk is formed between the tip of the arm 12 and the magnetic disk 15 due to leakage magnetic flux of the magnetic circuit. A magnetic shield plate 16 made of a high-di magnetic material such as permalloy is provided to prevent an adverse effect on the image 11.

The head 13 is inserted into the hole 16 formed in this magnetic shield @16.
The entire magnetic disk 15 is accessed through C. The arm 12 is formed of an integral part with a Chinese-Italian shape, and ribs 12α, 126, and 12C are provided on the peripheral wall to reduce the weight of the arm and provide sufficient rigidity. The head 13 includes a head arm 13α and a gimbal 13 as shown in FIG.
b and a head element 13c, the head arm 13
α is detachably attached to the arm 12 by screwing or the like. Incidentally, FIG. 4 is a view of the arm tip 81 viewed from the direction of arrow (7) in FIG. 3. Arm 12
A magnetic circuit 20 is provided at the tip of the arm 12 along the moving force of the arm 12. A core 17 is inserted into the coil 14 at the tip of the arm 12, and a magnet 18 supported by a rear yoke 19 is disposed above and below the core 17, forming a closed magnetic flux circuit together with the front yoke 20. The front yoke 20 may be provided with an air intake port to take in clean cooling air flowing on the surface of the magnetic disk and to suppress the temperature rise due to the heat generated by the coil. In the head drive actuator according to the present invention, the head mounting portion of the arm and the magnetic circuit portion, which is the source of the driving force of the arm, are arranged close to each other, so that the driving force of the magnetic circuit is used to generate the driving force of the arm. The image is transmitted to the head without being affected by shadows, which increases the precision of head positioning control.Also, the length of the arm can be increased to reduce the image quality, and the arm is lightweight due to its integral structure with the inner wall. At the same time, it is possible to achieve high speed access movement (8) of the head with low power consumption. Further, since the head and the point of application of the driving force are provided on the same side of the arm with respect to the rotation axis, it is possible to align the rotation axis with the impact center of the arm system. By aligning this axis of rotation with the center of the shaft, the pressure applied to the impact force on the p-bearing becomes extremely slow, and there is no need to increase the bearing strength to 1f'.

In this case, it is necessary to have some mass at the rear end of the arm, that is, on the opposite side of the rotational axis from the head position, but this mass has little influence on the increase in the moment of inertia. ! f
c.

Since the arm is constructed as a whole and the head is detachably attached to the arm, the head can be easily replaced.

[Brief explanation of the drawing]

FIG. 1 is a top view of a conventional rotary actuator for head linear motion, FIG. 2 is a top view of a head drive actuator according to the invention, FIG. 3 is a perspective view of a head rotation actuator according to the invention, and FIG. The diagram shows the magnetic 10111f for driving the actuator of the prefecture 3 diagram! FIG. 1.11...Rotation axis, 2.12...Arm. 3.13... Hera)", 14... Carp A,
. 5.15...Magnetic disk, 16...Magnetic shield plate. 20...Magnetic (b) path. Time Hand Applicant Fujitsu Co., Ltd. Patent Application Agent Akira Yoiki Patent Attorney Kazuyuki Nishidate Patent Attorney Yukio Uchida Akira Yamaguchi Figure 1 Figure 2 Figure 3 820

Claims (1)

[Claims] 1.? Place J number of heads on the side of the rotating arm. In the actuator for driving the head of a magnetic disk drive, in which all the coils for configuring the magnetic enclosure for driving the arm are provided on the rotary arm, the rotary arm is formed into a single body with a 9-in-1 shape! An actuator for driving a head of a magnetic disk device, characterized in that the coil is provided near the head mounting position of the rotary arm.