JPH0591710A - Linear motor for swing operation - Google Patents

Abstract

PURPOSE:To obtain a linear motor, wherein an enough large torque is obtained and the torque applied to the bearing of the shaft of the motor can be averaged, by providing the permanent magnets, whose magnetic poles of an even number are arranged alternately, and by providing the armature coils of the motor, which are opposed to the permanent magnets, and further, by using one of the magnet and the coil as the stator of the motor and using the other as the rotor of the motor. CONSTITUTION:When currents flow through sectoral coils 11-14 of a linear motor, e.g. the parts of the coils 11, 12 in the radial direction of the motor, which are in the downward magnetic field caused by a magnet 21, tend to rotate clockwise a base board 1 for the armature coils of the motor. All other coils generate similarly the torques which tend to rotate clockwise the armature of the motor. When the parts of the armature coils in the radial direction of the motor reach respectively the boundary parts between the adjacent magnetic poles of permanent magnets 21-24 for the field system of the motor, the generative torque of the motor is made zero. Also, when the currents of the coils flow in the reverse direction, the armature of the motor is rotated counter-clockwise. Therefore, the linear motor for swing operations, whose torque is large enough and is averaged around the bearing of the shaft of the motor, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-accuracy swing motion linear motor used for positioning a magnetic head in a magnetic disk device.

[0002]

2. Description of the Related Art Conventionally, a voice coil motor or a pulse motor has been used for the above applications. In addition, for small 3.5-inch and 2.5-inch class small-sized magnetic disk devices, voice coil motors that move in an arc shape and movable magnet type motors have been announced as those that meet the requirements for small size. A representative of the latter is shown in JP-A-63-277457.

[0003]

However, in the voice coil motor and the movable magnet type motor, which operate in an arc shape as described above, the torque generating portion is provided only on one side of the shaft, so that high torque can be obtained. Had a problem. Further, since the torque generating portions are not evenly distributed around the shaft, there is a problem that a non-uniform force is applied to the shaft to cause vibration. As an invention aimed at solving this point, for example, JP-A-62-
There are 268350. However, it was still insufficient in terms of thinning. From this point of view, an object of the present invention is to provide a linear motor having a thin structure capable of obtaining a sufficiently large torque, minimizing the torque applied to the bearing, and averaging the torque.

[0004]

According to the present invention, a structure similar to that of the rotary flat DC motor is adopted although the rotary operation is not performed. As a result, the number of torque generating points increases, sufficient torque is obtained, and the generated torque is evenly generated around the shaft, preventing harmful forces such as pulling the shaft in one radial direction. It became possible to do. It is not necessary to continue the rotation operation,
Since it is not necessary to consider the torque ripple, the number of thrust generating parts of the armature coil should match the number of magnetic poles of the field magnet.
In order to simplify the structure, we decided to use an even number that is as small as possible within the range where the required torque is obtained. Further, in order to obtain a large torque, it is necessary to add a yoke to both the armature side and the field side, but including the yoke in the rotor is not preferable from the viewpoint of inertia ratio, The yoke has a structure that does not rotate.

[0005]

EXAMPLES Examples of the present invention will be described below. (Embodiment 1) FIG. 1 is a diagram showing a first embodiment of the present invention. In the figure, 1 is a movable armature coil substrate, and 11 to 14 are four fan-shaped coils arranged thereon. Reference numeral 2 is a fixed field yoke, 21 to 24 are four magnets placed thereon, and 3 is another fixed field yoke. Although not shown in the drawing, the movable armature is rotatably supported by bearings, and is sandwiched by fixed field yokes from both sides with a slight gap. The relative positions of the field yoke and the armature in the rotation direction are approximately as shown in the figure. Therefore, the radial portions of the four coils are placed in the axially downward or upward magnetic field produced by the magnet.

Now, when a current is supplied to each of the four coils by an external power source as shown by arrows, for example, the magnet 21
The radial portions of the coils 11 and 12 placed in the downward magnetic field due to generate a force to the left in the figure according to Fleming's left-hand rule, thus attempting to rotate the armature clockwise. The same applies to the radial portions of the other coils, and each produces a torque that attempts to rotate the armature clockwise. When the radial part of the armature coil reaches the boundary with the adjacent magnetic pole of the field permanent magnet, the generated torque becomes zero and the armature coil does not rotate further. In other words, when an electric current in the direction shown is applied to the armature coils, an apparent north pole is generated on the lower surfaces of the coils 11 and 13, and an apparent south pole is generated on the lower surfaces of the coils 12 and 14. The attraction force causes the armature to rotate clockwise, and the coil 11 moves to a position where it overlaps with the magnet 21 and stops.

If, in the initial position as shown in FIG. 1, a current is applied to each coil in a direction opposite to that shown in the drawing, the armature rotates (in the same way) in the counterclockwise direction. A publicly known example of such a structure is Japanese Patent Publication No. 2-4072 (JP-A-60-239971). However, in the same example, the number of magnetic poles = number of coils × 2, whereas in the present embodiment, the number of magnetic poles = number of coils. In this way, the number of coils is doubled, and the number of turns (per coil) is halved instead.
As a result, the total value of the inductance of each coil can be reduced to about 1/2, and the outermost diameter of the coil,
If the inner diameter is the same, the thrust can be increased by about 15% by increasing the length of the thrust generating part. Therefore, the present embodiment has a structure superior in responsiveness and generated torque.

(Embodiment 2) FIG. 2 shows a second embodiment of the present invention. In the figure, 1 "is a movable armature substrate, and 11 to 14 are thin armature coils arranged thereon, which are formed by a printed wiring method and are wound many times on a plane.
2 and 3 are fixed field yokes, which are magnets 21
~ 24, and 31-34 are installed. Magnet 31 and
An N pole is attached to the lower surface of 33 and an S pole is attached to the lower surfaces of the magnets 32 and 34 so as to face the magnets 21 to 24, respectively, and generate downward and upward magnetic fields alternately.
The armature is rotatably supported with a slight air gap between the pole faces.

When a current is applied to the coil in the direction of the arrow, the armature rotates clockwise, and when a current is applied in the direction opposite to the arrow, the armature rotates counterclockwise. The operating principle is exactly the same as that of the first embodiment. Also in the case of this embodiment, the armature has a range between the position where the coil 11 is sandwiched between the magnets 21 and 31 and the position where the coil 12 is sandwiched between the magnets 21 and 31, that is, a maximum of 90 degrees. You can swing with. When it is not necessary to increase the swing angle in this way, a stopper may be provided or the drive current may be controlled. In the case of this embodiment, the armature coil is sandwiched between the permanent magnets, so that the magnetic field placed on the coil is strong and sufficient torque can be generated even if a thin coil with a small space is used. is there.

(Embodiment 3) FIG. 3 shows a third embodiment of the present invention. In the figure, 1 is a fixed armature yoke, 11, 12, 1
Reference numerals 3 and 14 denote thin armature coils disposed on the thin armature coil, which are formed by the printed wiring method and are wound a large number of times on a plane. Fixed armature yoke 1 ′ and armature coil having the same structure
11 ', 12', 13 ', 14' are symmetrically arranged on the upper surface. Reference numeral 2 is a mover, and reference numerals 21, 22, 23 and 24 are magnetizing magnet portions. The magnetic poles shown are those that appear on the upper surface, and opposite magnetic poles are present on the lower surface. The mover is sandwiched between fixed armatures with a slight gap and is rotatably supported.

Now the coils 11, 12, 13, 14 and 11 ', 1
When a current is applied to 2 ', 13', 14 'in the direction of the arrow, the coil 11,
An S pole or an N pole appears on the surface (upper surface) of 13 or 12, 14 and an N pole or an S pole appears on the surface (lower surface) of the coils 11 ', 13' or 12 ', 14', respectively. . Therefore, the mover receives a force in the clockwise direction and rotates.
When the current direction is opposite to that shown, the mover rotates counterclockwise. The structure as in this embodiment has four poles, so that a sufficient torque can be obtained despite its small diameter, and it does not require electric wiring for the movable part, so it is highly reliable.

[0012]

As described above, according to the present invention, the torque is sufficiently large and is averaged around the bearing,
It is possible to obtain a linear motor for swing operation, and it is possible to improve reliability of the disk device.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a third embodiment of the present invention.

[Explanation of symbols]

 1 Armature Yoke 1 ′ Armature Yoke 1 ″ Armature Coil Board 11 Armature Coil 12 Armature Coil 13 Armature Coil 14 Armature Coil 11 ′ Armature Coil 12 ′ Armature Coil 13 ′ Armature Coil 14 ′ Armature Coil 2 Field yoke 3 Field yoke 21 Field permanent magnet 22 Field permanent magnet 23 Field permanent magnet 24 Field permanent magnet 31 Field permanent magnet 32 Field permanent magnet 33 Field permanent Magnet 34 Field permanent magnet

Claims (3)

[Claims] 1. A permanent magnet for a plate-shaped field magnet, in which an even number of magnetic poles are alternately arranged at substantially equal intervals around a rotation axis, and a planar armature coil whose number is equal to the number of poles facing the permanent magnet. A linear motor for swing operation, characterized in that one is a stator and the other is a movable element. 2. A pair of field permanent magnets are provided,
The armature coil is positioned so as to be sandwiched between these magnets,
The swing operation linear motor according to claim 1, wherein the linear motor is of a moving coil type. 3. The armature coil is provided with two sets arranged on a yoke, and the permanent magnet for field is positioned so as to be sandwiched between them, and is of a movable magnet type. Item 1. A linear motor for swing operation according to item 1.