JPS61154471A - Rotary actuator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotary actuator for driving a head or the like of a fixed disk device.

BACKGROUND OF THE INVENTION In recent years, as the functionality of personal computer computers has improved, the capacity of external storage devices has been increasing. Against this background, there is a demand for smaller fixed disk devices, and in order to miniaturize the device, it is also necessary to make the actuator for driving the magnetic head smaller and more compact.

Hereinafter, an actuator used in a conventional fixed disk device will be explained.

FIG. 6 shows the entire cross section of the drive part of the first example of the conventional head drive actuator, in which 11 is a coil, 12
is a magnet, 13 is a stator yoke, 14 is a magnetic head, 15
is a magnetic disk.

Note that a support mechanism for supporting the movable coil is not shown in this figure.

This drive system is usually called a voice coil type linear motor, and thrust in the direction of the arrow is generated by magnetic flux interlinking the voice coil and coil current. The direction of movement can be selected by the direction of the coil current. The positioning of the head is usually performed by obtaining a signal from a surfactant previously recorded on the disk surface to form a closed position loop.

FIG. 7 is a perspective view showing a second conventional example, in which 16 is a voice coil, 17 is a magnet, 18 is a stator yoke, 19 is a bearing mechanism, 20 is a magnetic head, and 21 is a magnetic desulfur. Voice coil and stator yoke.

It is a rotary type actuator in which the magnet is formed into an arc shape and is supported at one point.

FIG. 8 is a perspective view showing the third conventional example, in which 22 is a stepping motor, 23 is a pulley, 24 is a steel band, 2
6 is a bearing mechanism, 26 is a magnetic cover, and 27 is a magnetic disk.

Problems to be Solved by the Invention However, in the above configuration, in the voice coil type motor shown in FIG.
, so the gap must be greater than the thickness of the entire coil 11. The air gap usually has several values, so the magnetic flux density cannot be increased, and the effective area sound must be increased to generate thrust, which has the disadvantage that the motor becomes larger overall. Also, although it is not shown in Figure 4, is the linear motion of the voice coil? The supporting mechanism that supports it also becomes complicated.

Further, in the rotary type shown in FIG. 7, the bearing mechanism is simple, but the stator constituting the magnetic circuit is stiffer, as in the example shown in FIG. 6.

Furthermore, in the example shown in Fig. 8, since a rotary stepping motor is used as the drive source, positioning can be performed without position feedback, but conversely, fine pitch positioning is not possible, so it is necessary to increase the storage capacity. It is not suitable for increasing recording density.

Does the present invention solve the above-mentioned conventional problems? The purpose of the present invention is to provide a rotary type actuator that is small in size, has high output, and has a simple support mechanism.

Means for Solving All Problems The present invention provides a mover having magnetic pole teeth formed at equal angles in the circumferential direction of the outer circumferential surface of a magnetic core having a substantially fan-shaped cross section, and a mover having magnetic pole teeth formed on the outer circumferential surface of the mover. A plurality of mutually phased bearing mechanisms that support the mover for full rotation at the center of the circular arc of the mover, and magnetic pole teeth that are arranged with a constant gap from the outer peripheral surface of the mover's magnetic pole teeth and have the same angular pitch as the mover's magnetic pole teeth. The rotary actuator is entirely composed of a stator core equipped with different groups of magnetic pole teeth, a winding, and a stator equipped with a detector that detects the entire position of the movable magnetic pole teeth.

Effects According to the above configuration, the stator and the movable element can be arranged so that the outer circumferential surfaces of the movable element are flush with each other, and by reducing the gap, it is possible to obtain a compact and high-output actuator.

Embodiment FIGS. 1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a perspective view, FIG. 2 is a top view, and FIG. 3 is a sectional view. In FIGS. 1 to 3, reference numeral 1 denotes a mover core equipped with magnetic pole teeth (not shown) formed at equal angular pitches in the circumferential direction of the outer peripheral surface, and 2 a mover frame that supports the mover core 1. , 3 is a stator core that rotatably supports a movable element composed of a movable core 1 and a movable frame 2, and is arranged with a constant gap from the outer peripheral surface of the magnetic pole teeth of the movable core 1; 6 is a winding wound around the stator core 4, and 6 is a position detector that detects the entire position of the movable magnetic pole teeth.

The stator core 4 has six magnetic pole tooth groups consisting of magnetic pole teeth with the same angular pitch as the mover magnetic pole teeth, a, b, c
have a phase difference of a small pitch, respectively, and similarly, d, e, and f have a phase difference of a small pitch and a small pitch, respectively. and a and d
, b, e, c (!: f have a phase difference of the pitch of each pole. In addition, the magnetic pole tooth groups a, b, c and d, e, f'
Although they are mechanically coupled, the connecting portion is magnetically open due to magnetic saturation. The winding 6 has each magnetic pole tooth group a.

br' + dl' If, respectively.

In the above configuration, when the winding 5 is not energized, no force acts between the stator core 4 and the movable core 1.

In the so-called hybrid type in which a magnet is added to the stator, cogging occurs and affects positioning accuracy, but cogging does not occur in the device of the present invention.

If the energization command to each winding is given from the outside, this device operates like a normal stevening motor.

In the present invention, switching of the energized windings is performed by a signal from the position detector 6. The position detector 6 is equipped with three sensors, and each sensor is arranged at a position shifted by 1+n pitches (n=o, 1.2...) with respect to the mover magnetic pole teeth. The rotation of the mover generates signals with a phase shift of 1200 degrees. This signal switches the current.

For example, the $ pole tooth groups a, b, c of the stator core 4.

d, e, and f are 0 pinch and V3 pitch, respectively.

Assume that the pitch is % pitch, the pitch is 112 + almost pitch, and the pitch is shifted by 112 + almost pitch. Also, assume that the signal from the position detector 6 is as shown in FIG. At that time, if driven by a basic circuit as shown in FIG. 6, the mover rotates.

The drive circuit can also adjust the timing to maximize the torque generated by each core.

Further, in the structure of the present invention, the gap size can be made as small as 100 μm or less, so it is possible to increase the torque/volume ratio compared to a voice coil motor.

Furthermore, if the applied current is made into a sine wave, the torque generation from each core can be smoothly switched, and operation with almost no torque ripple can be obtained.

Effects of the Invention As described above, according to the present invention, the gap between the mover core and the stator core can be reduced, so that the torque is large. Since there is no cogging, positioning operations are easier to perform. By applying full sinusoidal current to the windings, operation with almost no torque ripple can be obtained. Due to the rotary structure, there are many advantages such as high accuracy and a small number of parts.

[Brief explanation of the drawing]

1 to 3 show all embodiments of the present invention, with FIG. 1 being a perspective view, FIG. 2 being a top view, and FIG. 3 being a sectional view. Fig. 4 is a waveform diagram of the output signal of the position detector, Fig. 6 is a circuit diagram of the basic drive circuit, Fig. 6 is a sectional view of a conventional linear voice coil type actuator, and Fig. 7 is a conventional rotary voice coil type actuator. FIG. 8 is a perspective view of an actuator using a conventional stepping motor. 1... Mover core, 2... Mover frame, 3... Bearing device, 4... Stator core, 5... Winding, 6...Position detector. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure/-11 Mover gore Figure 3 Area 0 Figure 5 Figure 6 Figure 7? l

Claims (1)

[Claims] A movable element having magnetic pole teeth cut at equal center angular pitch along the circumferential direction of the arcuate outer peripheral surface of a core made of a magnetic material having a substantially fan-shaped cross section, and the movable element being rotatable around the arc center. a bearing device supporting the movable element; and a plurality of magnetic pole tooth groups arranged to maintain a constant gap with the outer circumferential surface of the magnetic pole teeth of the movable element and having mutually shifted phases, each consisting of magnetic pole teeth having an angular pitch equal to that of the movable element magnetic pole teeth. A rotary actuator consisting of a stator core provided with a stator core, a winding wire, and a stator provided with a position detector that detects the position of a movable magnetic pole tooth.