JPH073824Y2 - Linear motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a linear motor including a linear encoder for head positioning and / or speed detection of a magnetic disk, for example.

[Conventional technology]

Conventionally, a linear motor is often used as a head drive device for a magnetic disk or the like because it is relatively lightweight and can be manufactured at low cost.

FIG. 2 is a side sectional view showing an example of a conventional linear motor. In FIG. 2, reference numeral 1 denotes a yoke, which is made of a ferromagnetic material and has a flat plate shape, for example. 2 is a permanent magnet,
It is magnetized in the thickness direction, and a plurality of magnets are fixed to the surface of the yoke 1 so that N and S magnetic poles appear alternately on the surface. Support plates 3, 3 are provided at both ends of the yoke 1, and a bottom plate 5 is fixed below the yoke 1 with a slight gap 4 therebetween. Next, a movable member 6 supports the photoelectric conversion means 7 and the coil 8 and is formed so as to be movable along the longitudinal direction of the yoke 1. The photoelectric conversion means 7 is provided so as to embrace the linear encoder 9 provided between the support plates 3 and 3, and the coil 8 is provided within the range in which the magnetic field of the permanent magnet 2 acts.

FIG. 3 is an enlarged cross-sectional view of an essential part of the photoelectric conversion means 7 shown in FIG. 2, FIG. 4 is a view taken along the line AA in FIG. 3, and the same parts are designated by the same reference numerals as those in FIG. . In both figures, reference numerals 71 and 72 respectively denote a light emitting element and a light receiving element, which are provided so as to face each other via the linear encoder 9. Reference numeral 73 is an index, which is provided, for example, on the facing surface of the linear encoder 9 on the light emitting element 71 side. Next, in the index 73, the origin slit 74 and the A phase 75 and B phase consisting of a plurality of slits
Provide 76. The linear encoder 9 is provided with an origin slit 91 corresponding to the origin slit 74 and a slit 92 corresponding to the A phase 75 and the B phase 76. In this case, A phase 75, B phase 76
The pitch P of the slit and the slit 92 in
Set to 100 μm. Next, the A phase 75 is provided at a position of t = np (n is a positive integer) from the origin slit 74, and the B phase 76 is provided at a position of t ± 1 / 4P from the origin slit 74. As a result, the origin slit 74 and the A phase 75 are in the same phase, and the origin slit 74
And B phase 76 have a 90 ° phase difference relationship.

With the above configuration, if the coil 8 is energized in the forward and reverse directions in FIG. 2, the coil 8 or the movable member 6 can be moved in the left and right directions according to Fleming's left-hand rule. In this case, the photoelectric conversion means 7 generates photoelectric conversion outputs having 90 ° phases different from each other through the A phase 75 and the B phase 76 by the configuration shown in FIG. 3 and FIG. This can be obtained, and by inputting this electric signal to the arithmetic unit and the control unit (neither is shown), the movable member 6 can be positioned and / or the speed can be detected.

[Problems to be solved by the device]

In the above-mentioned configuration, as a method of detecting the velocity and position information from the linear encoder 9 by the photoelectric conversion means 7, a method of utilizing a diffraction effect, a method of detecting a reflected wave due to refraction, and a bright and dark stripe at the time of transmitting light are used. Although there is a method of using (moire fringes), in any case, it is necessary to provide the linear encoder 9 with a pattern of slits 92 having light and dark stripes arranged at equal intervals along the longitudinal direction. When forming such a slit pattern, a glass vapor deposition means for vapor depositing a transmission slit on glass and an etching means using a base material such as Ni alloy are most commonly used. Among them, the former linear encoder formed by the glass vapor deposition means has an advantage that it can be finely processed and has a high rigidity, but on the other hand, it requires a lot of time and man-hours for processing, and therefore the manufacturing cost is high. It is bulky and unsuitable for mass production. The latter etching means is suitable for mass production, but is insufficient in terms of rigidity and has a problem that it cannot maintain a flat shape by itself. That is, the number of slits is increased to improve the resolution.
This is because, if more than 10 strips / mm is required, the base material will be tape-shaped with a thickness of 0.1 mm or less. It should be noted that the means for adhering the above-mentioned tape to, for example, a rigid glass is complicated and costly, and causes a decrease in accuracy.

An object of the present invention is to solve the problems existing in the above-mentioned prior art, and to provide a linear motor or a linear motor having a simple structure and a high precision.

[Means for Solving the Problems]

In order to achieve the above object, in the present invention, a yoke formed by fixing a permanent magnet to the surface, a photoelectric conversion means, and a coil provided within a range in which the magnetic field of the permanent magnet acts, and supporting the yoke. A linear motor comprising a movable member formed movably along the surface and a linear encoder facing the photoelectric conversion means and provided parallel to the surface of the yoke. A technical means is adopted in which a tape-shaped linear encoder provided with a transmission slit is attached to the end portion of the yoke via a tension applying means and a relative position adjusting means with respect to the yoke.

In the present invention, the tension applying means is preferably a tension coil spring.

〔Example〕

FIG. 1 is a sectional side view of an essential part showing an embodiment of the present invention.
The same parts are designated by the same reference numerals as in FIG. First
In the figure, 10 is a linear encoder, which is made of Ni alloy into a tape shape with a width of 10 mm and a thickness of 0.1 mm, and has 10 slits / mm (not shown) formed by etching. Next, a protrusion 11 is provided on the side surface of the left support plate 3a and a tension coil spring 12 is attached to the left support plate 3a.
A curved surface portion 13 of mm is provided. Next, an adjusting member 14 having an L-shaped cross section is provided on the right support plate 3b so as to be movable in the left-right direction, and an adjusting screw 15 is screwed. The linear encoder 10 is mounted between the tension coil spring 12 and the adjusting member 14 to form a linear motor.

With the above configuration, the tension of the tensile coil spring 12 is applied to the tape-shaped linear encoder 10 by, for example, 700 g, so that the flatness in the width direction as well as the longitudinal direction is maintained at 0.05 or less. That is, the linear encoder 10 includes the support plate 3
This is because the upper end portions of a and 3b are in a so-called line contact state over the entire width direction. In this case, the linear encoder 10
Can be turned about 90 ° at the upper end of the support plate 3a, but since the curved surface portion 13 is provided at the upper end of the support plate 3a,
The direction change is extremely smooth and the tension coil spring 12
The transmission of tension by is also uniform and smooth. When adjusting the relative position of the linear encoder 10 to the yoke 1 (for example, 0-point adjustment), the adjusting member 15 may be rotated to finely move the adjusting member 14 left and right.

In the present embodiment, an example in which a tension coil spring is used as the tension applying means for the linear encoder has been described, but a spring having another configuration or rubber or another elastic member may be used. Further, an elastic body such as felt or urethane may be provided on the curved surface portion of the upper end portion of the support plate which is in contact with the linear encoder. Further, the material forming the linear encoder may be a metal material other than the Ni alloy, and in short, the function is the same as long as the light transmitting slit can be formed by the etching means. The configuration of the linear motor main body may be other than that of this embodiment. In short, a coil is provided within the range in which the magnetic field of the permanent magnet acts, and thrust is applied between the two by energizing the coil. If applicable, it is applicable.

[Effect of the Invention] Since the present invention has the configuration and operation as described above,
The structure is simple, and the manufacturing cost can be significantly reduced as compared with the one equipped with a glass vapor deposition type linear encoder. In addition, since the resolution can be improved to 10 lines / mm or more, it can contribute to higher speed and higher accuracy of the linear motor.

[Brief description of drawings]

FIG. 1 is a sectional side view of an essential part showing an embodiment of the present invention, FIG. 2 is a sectional side view of an essential part showing an example of a conventional linear motor, and FIG.
FIG. 4 is an enlarged sectional view of an essential part of the photoelectric conversion means shown in FIG.
The figure is a view taken along the line AA in FIG. 1: yoke, 2: permanent magnet, 7: photoelectric conversion means, 10: linear encoder, 12: tension coil spring.

Claims (2)

[Scope of utility model registration request] 1. A yoke having a permanent magnet fixed to the surface thereof,
A movable member that supports the photoelectric conversion means and a coil provided within the range in which the magnetic field of the permanent magnet acts and is movably formed along the surface of the yoke; In a linear motor comprising a linear encoder provided in parallel with the surface of a yoke, a tape-shaped linear encoder made of a metal material and provided with a plurality of light transmitting slits is provided with a tension applying means and a yoke at the end of the yoke. A linear motor, which is mounted via a relative position adjusting means. 2. The linear motor according to claim 1, wherein the tension applying means is a tension coil spring.