JPS6314584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to the basic configuration of a linear pulse motor that is small and has a small maximum displacement on the movable side.

Generally, a linear pulse motor displaces the movable side in steps by a fixed distance for each input pulse supplied to the primary coil. Along with this action,
Linear pulse motors are used to feed the heads of various printers that require accurate positioning control, and to feed the heads of photoelectric readers. The conventionally commonly used specific example of this linear pulse motor is the first one.
As shown in FIG. That is, Fig. 1 is a partially cutaway front view, and Fig. 2 is a partially cutaway side view. In each figure, 1 is the primary side of the linear pulse motor, and the front center part is in a magnetically shrunk state. There are 2
two iron cores 2, 3, side plates 4, 5 that fix each iron core 2, 3 on both sides, permanent magnets 6, 7 magnetized with the polarities shown on the back of each of the above-mentioned iron cores 2, 3, the permanent A magnetic plate 8 joined to the back side of the magnets 6, 7, magnetic poles 2a, 2b, 3 formed on each of the above-mentioned iron cores 2, 3.
It is composed of coils 9a to 9d attached to wheels 4a and 3b, and wheels 12 to 15 rotatably supported by shafts 10 and 11 supported under both sides of each side plate 4 and 5. And each of the magnetic poles 2a, 2b, 3a, 3b
2a1, 2b with a difference of 1/4 pitch
1, 3a1, and 3b1 are formed. 16 is a scale forming the secondary side of the linear pulse motor, and the above-mentioned magnetic pole tooth portions 2a1, 2b1, 3a1,
A tooth portion 16a having the same pitch as 3b1 is formed.

In the linear pulse motor shown in FIGS. 1 and 2 above, when driving, for example, by a one-phase excitation method, teeth formed on each magnetic pole 2a, 2b, 3a, 3b are formed in the process of sequentially exciting each coil 9a to 9d. The portions 2a1, 2b1, 3a1, and 3b1 sequentially face the tooth portions of the secondary scale, thereby stepping forward by 1/4 pitch (in the actual operation process, it appears to be a continuous operation). At this time, the primary main body 1 and the secondary scale 16 are put into practical use by fixing one and moving the other.

Incidentally, in recent years, with the development of office automation equipment, there has been a strong trend toward miniaturization and thinning of various information terminal devices, and this tendency is also strong in floppy disk drives, for example. These market demands have led to a demand for ultra-small and ultra-thin linear pulse motors.

Currently, the trolley-type linear pulse motor shown in FIGS. 1 and 2 cannot meet the above-mentioned market demands. In other words, in the above-mentioned floppy disk drive, etc., normally a thrust of about 10 to 100 g and a stroke of about 10 to 30 mm are sufficient, whereas with the above-mentioned conventional trolley type linear pulse motor, the thickness W is small even for the purpose of miniaturization. There is a limit to the reduction in order to obtain the minimum strength of the wheel attachment mechanism, and the reduction in height H is limited to the first and second teeth where the opposing surfaces of the primary and secondary teeth are orthogonal to the magnetic flux passing through the magnetic poles. This is difficult with the conventional configuration shown in the figure. On the other hand, there is a limit to the shortening of the length L based on the necessity of arranging the magnetic poles in the moving direction of the linear pulse motor movable side.

The purpose of this invention is to provide a linear pulse motor that uses the same driving principle based on the characteristics of the configuration of the primary side of the linear pulse motor, but is miniaturized to suit low thrust and short stroke characteristics. be.

The illustrated embodiment will be specifically described below. Fig. 3 shows a plan view, and Fig. 4 shows a side view. In each figure, 17 is the primary side of the linear pulse motor, and iron cores 18 and 19 are magnetized with the polarity shown to connect both sides of the motor. Permanent magnets P1 and P2 are composed of magnetic poles 20 to 23 extending perpendicularly from mutually opposing surfaces of the iron cores 18 and 19, and excitation coils 24 to 27 attached to the magnetic poles 20 to 23.
At this time, the magnetic pole faces 20a to 23 of each magnetic pole 20 to 23
a is set in a direction 90 degrees from the direction in which the magnetic poles 20 to 23 extend from the magnetic pole mounting surfaces of the iron cores 18 and 19 (located on the upper surface in the figure).
Teeth are formed on the surfaces of these magnetic pole faces 20a to 23a, and each tooth pitch is formed to be equal to the secondary side tooth pitch, which will be described later.
a. The tooth portions formed on 22a, 21a and 23a are sequentially displaced by 1/4 pitch.
28 is a secondary side scale, and the above-mentioned magnetic pole faces 20a to 2
A linear pulse motor is configured with the primary side 17 by maintaining a constant gap G at the magnetic pole surface 20
Each magnetic pole surface 20a to 23a is provided on the opposing surface of a to 23a.
Teeth 28a are formed with the same pitch as the teeth formed in . Reference numeral 29 denotes a bearing ball, which rolls while maintaining a constant distance between the primary side of the linear pulse motor main body and the facing surface of each tooth portion of the scale 28, and also serves as a guide for the scale 28.

The balls 29 are arranged at four locations on both sides of the iron cores 18 and 19, and their rolling ranges are regulated by guides (not shown), so that the rolling range of the movable side (for example, the scale 28) is controlled by the rolling range of the balls 25. It is set to twice the range.

In the configuration shown in FIGS. 3 to 5 above, now,
Each convex part of the tooth part formed on the magnetic pole surface 23a and the tooth part 28a formed on the scale 28 obtains an attractive force as a magnetic flux is generated that promotes the magnetic flux of the permanent magnet P2 with the excitation of the excitation coil 27. When the excitation coil 27 is de-energized and the excitation coil 25 is simultaneously excited from the state (the state shown in FIG. 4), there is a gap between the teeth formed on the magnetic pole face 21a and each convex portion of the scale teeth 28a. Magnetic flux of permanent magnet P2 and exciting coil 2
5 is added to the magnetic flux generated due to the excitation of the scale 24, and a strong magnetic attraction force acts, causing a displacement of 1/4 pitch (if the primary side 17 is fixed, the scale 24 is displaced to the left). Next, by sequentially exciting only the excitation coils 26 and 24, a displacement of 1/4 pitch is generated based on the same principle. By repeating the above operations, the linear pulse motor displaces the movable side by 1/4 pitch, thereby positioning and controlling the controlled object (not shown) attached to the movable side. During operation of this linear pulse motor, the total magnetic flux generated from the primary magnetic flux generation source is transmitted between the teeth formed on the magnetic pole faces 20a to 23a and the teeth 28a formed on the scale 28, as shown in FIGS. 3 to 5. The liquid always flows into the scale 28 with a direction change in the plane, and then flows out from the scale.

In addition, although FIGS. 3 to 5 showing the embodiments of the present invention described above show a configuration in which each magnetic pole is provided with an independent excitation coil, the number of excitation coils can be halved by controlling the direction in which the current flows in the coil. . In addition, the exciting coils can be located on both sides, and various modifications are possible.

On the other hand, the excitation means of the excitation coil is not limited to the method of exciting one phase at a time as explained above, but can also be the well-known two-phase excitation, and is also applicable to reactance type linear pulse motors that do not have permanent magnets. can.

As described above, in the linear pulse motor according to the present invention, the direction in which the magnetic flux generated in the primary main body passes through the magnetic pole, and the direction in which the magnetic flux passes between the magnetic pole surface and the tooth portion formed on the scale surface facing the magnetic pole surface. The gist of the arrangement is that the direction is perpendicular to the current direction. Based on this configuration, especially in small thrust applications, the height H of the conventional primary side is determined by the length of the magnetic pole (determined by the coil winding length), the gap and the thickness of the scale ( In contrast, the height of the linear pulse motor according to the present invention is determined by the sum of the thickness of the magnetic pole core, the gap, and the thickness of the bearing support frame. The thickness can be reduced and the height can be reduced.
Furthermore, in contrast to the conventional configuration in which the magnetic pole faces are arranged continuously along the moving direction of the linear pulse motor, in the linear pulse motor according to the present invention, the magnetic pole faces allow the magnetic flux to pass through the inside of the magnetic poles. Since they are parallel to each other, they can be arranged almost centrally, and accordingly, the length of the primary side of the linear pulse motor can be shortened. Moreover, since the primary and secondary gap maintaining mechanisms can be carried out by very small-diameter balls together with scale guides, there is no tendency to increase the length in the width direction compared to the prior art. For these reasons, linear pulse motors have the advantage of being able to be miniaturized to suit use in various office automation equipment with small thrust and small strokes.

[Brief explanation of the drawing]

1 and 2 are partially cutaway front and side views showing a conventional configuration, respectively, and FIGS. 3, 4, and 5 each show one specific configuration of a linear pulse motor according to the present invention. FIG. 2 is a plan view, a front view, and a side view. 20-23...Magnetic pole, 20a-23a...Magnetic pole surface, 24...Scale, 24a...Scale tooth portion.

Claims (1)

[Claims] 1. Two primary magnetic pole surfaces each having teeth formed on the secondary scale tooth surface at the same pitch as the secondary scale tooth but with a 1/4 pitch shift.
The rows are arranged to face each other with a certain gap, and the magnetic pole surfaces of each row are connected by magnetic path forming iron cores that extend parallel to the magnetic pole surfaces in opposite directions, and each iron core is equipped with an excitation coil. A linear pulse motor featuring