JP5207656B2 - Planar type electromagnetic actuator - Google Patents

Description

  The present invention relates to a planar type electromagnetic actuator manufactured using a semiconductor manufacturing technology for driving a movable part using electromagnetic force, and more particularly to a technique for improving the swing stability of the movable part of the planar type electromagnetic actuator.

Conventionally, as this type of planar electromagnetic actuator, for example, as described in Patent Document 1, a semiconductor substrate is anisotropically etched to move to a frame-shaped fixed portion, a movable portion, and the fixed portion. The torsion bar that pivotally supports the part is integrally formed, the drive coil is provided on the movable part, and the static magnetic field acts on the drive coil part at both ends of the movable part parallel to the axial direction of the torsion bar For example, a permanent magnet is provided as the generating means, and the movable part opposite to the axial direction of the torsion bar is parallel to the axial direction of the torsion bar by the interaction between the magnetic field generated in the drive coil by the current supplied from the drive circuit and the static magnetic field by the permanent magnet. The movable part is driven around the axis of the torsion bar by applying an electromagnetic force (Lorentz force).
Japanese Patent No. 2722314

  By the way, when this type of conventional planar type electromagnetic actuator is driven to swing in a gas, the turbulence of the gas around the movable part has a great influence on the swinging operation of the movable part, and the swinging operation of the movable part is prevented. It is a disturbing factor. This will be specifically described with reference to FIGS. 6A to 6D. When the movable part operates, a large gas vortex is generated in the vicinity of the edge of the movable part opposite to the operation direction (see FIG. 6A). )). The vortex of the gas moves in the moving direction of the movable part with the movement of the movable part (FIG. (B)). Thereafter, when the movable part is reversed, the gas vortex collides with the edge of the movable part, and a moment M in the direction opposite to the operation direction of the movable part is generated and acts on the edge of the movable part (FIG. (C)). . This moment M causes a shift in the swing position of the movable portion as shown by the solid line with respect to the original swing position of the movable portion indicated by the broken line (position when there is no moment M) (FIG. 4D). This may cause a problem that the stability of the swinging motion of the movable part is disturbed.

  The present invention has been made paying attention to the above problems, and provides a planar electromagnetic actuator capable of stabilizing the swinging motion of the movable part by suppressing the generation of vortices accompanying the swinging motion of the movable part. The purpose is to do.

For this reason, the invention of claim 1 is a planar electromagnetic actuator for driving a movable part pivotally supported on a fixed part via a torsion bar by an electromagnetic force, in an axial direction of the torsion bar of the movable part. The edge portion substantially parallel to the axial direction is formed into a concavo-convex shape in the cross section of the movable portion parallel to the axial direction, and the projecting dimension and pitch of the convex portion at the edge portion are set to the drive frequency, amplitude, and the torsion It is characterized in that it is determined from the diameter of the vortex determined in relation to the length from the axial center of the bar to the end edge .

In such a configuration, the axial direction substantially parallel end edges of the torsion bar of the movable portion by a shape of irregularities, the generation of vortices of the gas in the vicinity movable portion end edge portion during the swinging operation of the movable portion can be suppressed The generated vortex is finely dispersed by the concavo-convex portion, and the moment in the direction opposite to the moving portion operating direction acting on the moving portion can be reduced.

In concrete terms, as in claim 2, the protrusion dimension and pitch of the convex portion, or equal to about 1/5 to about 5 times the diameter of the vortex.

As in claim 3, the movable portion is a frame-shaped outer movable portion pivotally supported by the fixed portion via an outer torsion bar, and the outer movable portion and the outer torsion bar in the axial direction. An inner movable portion that is pivotally supported via a right-angled inner torsion bar, and an end edge portion of the outer movable portion that is substantially parallel to the axial direction of the outer torsion bar and the inner movable portion. An end edge portion substantially parallel to the axial direction of the inner torsion bar may be the uneven shape.

In the configuration of claim 3 , as in claim 4 , the side edge portion of the inner movable portion that is substantially parallel to the axial direction of the outer torsion bar may have an uneven shape.

According to the planar type electromagnetic actuator of the present invention, since the axial direction substantially parallel end edges of the torsion bar of the movable portion has an irregular shape, vortices of gas occurring near the edge portions by the swinging operation of the movable portion And the generated vortices can be finely dispersed. Thus, the opposite direction of the moment the movable parts operating direction acting on the edge portion of the vortex during reverse operation of the movable portion can be reduced, it is possible to increase the stability of the swing motion of the movable portion.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a plan view of a first embodiment of a planar electromagnetic actuator according to the present invention.
In FIG. 1, a planar electromagnetic actuator 1 of this embodiment generates a magnetic field by energizing a movable part 4 pivotally supported by a frame-like fixed part 2 via a pair of torsion bars 3 and 3. Driving coil 5 and, for example, a permanent magnet 6 which is a static magnetic field generating means for applying a static magnetic field to the driving coil 5, and the interaction between the magnetic field generated in the driving coil 5 by energization and the static magnetic field of the permanent magnet 6 is provided. Electromagnetic force (Lorentz force) is applied to both edge portions of the movable portion 4 parallel to the axial direction of the torsion bars 3 and 3 to rotate the movable portion 4.

  The fixed part 2, the torsion bars 3, 3 and the movable part 4 are integrally formed by anisotropically etching a semiconductor substrate such as a silicon substrate. And the movable part 4 which is the characteristic of this invention is made into the uneven | corrugated shape by the triangle which formed the both-ends edge part 4a substantially parallel to the axial direction of the torsion bars 3 and 3 at equal intervals. As shown in FIG. 1, the drive coil 5 is wound along the periphery of the movable part 4 and electrically connected to a pair of electrode terminals 7 and 7 formed on the fixed part 2 through the torsion bars 3 and 3. To do. The number of turns of the drive coil 5 is one in order to simplify the illustration in FIG. The permanent magnet 6 is provided on the outer side of the fixed portion 2 so that opposite magnetic poles face each other with the movable portion 4 interposed therebetween as shown in the figure.

Next, the operation of the planar electromagnetic actuator of this embodiment will be described.
The driving principle of the movable part 4 is the same as in the prior art. When a current is passed through the drive coil 5 on the movable part 4, a magnetic field is generated, and the Lorentz force is generated by the interaction between this magnetic field and the static magnetic field by the permanent magnets 6 and 6. Generated, electromagnetic forces in opposite directions are generated at both end edges of the movable part 4 parallel to the axial direction of the torsion bars 3, 3, and the movable part 4 rotates around the torsion bars 3, 3. With this turning operation, the torsion bars 3 and 3 are twisted to generate a spring force in the torsion bars 3 and 3, and the movable portion 4 is rotated to a position where the spring force and the generated electromagnetic force are balanced. If an alternating current such as a sine wave is passed through the drive coil 5, the movable part 4 can be swung. Thereby, if the movable part 4 is provided with a reflecting mirror, the light beam can be deflected and scanned. If the frequency of the alternating current supplied to the drive coil 5 is set to the resonance frequency of the oscillating motion of the movable part 4, An optical scanning device capable of continuous scanning at a constant period can be realized.

  When the planar electromagnetic actuator 1 is swung in a gas, as shown in FIG. 6, near the movable part edge 4a on the opposite side of the movable part 4 due to the turbulence of the gas around the movable part 4 In the planar electromagnetic actuator 1 of the present embodiment, the generation of vortices can be suppressed by the uneven shape of the end edge portion 4a of the movable portion 4, and the generated vortices are finely dispersed. For this reason, when the movable part 4 is reversed, the moment M (see FIG. 6) in the direction opposite to the movable part operating direction acting on the edge part 4a due to the collision between the edge part 4a and the vortex can be reduced as compared with the prior art. The displacement of the movable part 4 is suppressed, and the swinging operation of the movable part 4 is stabilized.

  The protrusion length a and the pitch b of the protrusions in the concavo-convex shape of the end edge 4a are small in the vortex suppression and dispersion effect even if they are too large or too small. If it is too large, the size of each of the dispersed vortices is still sufficiently large, and the moment M acting on the edge 4a is still large, so that a sufficient effect cannot be obtained. If it is too small, the vortices are not sufficiently dispersed, unlike the conventional movable part, so that a sufficient effect cannot be obtained.

  Appropriate dimensions of the protrusion length a and pitch b of the convex portion are related to the diameter of the vortex generated (hereinafter referred to as the vortex diameter), and the vortex diameter varies depending on the operation speed of the movable portion 4 and the operation of the movable portion 4. The speed depends on the drive frequency and amplitude of the movable part 4 and the length L (shown in FIG. 1) from the axial center of the torsion bars 3 and 3 to the edge part 4a. Therefore, it is preferable to determine appropriate dimensions of the protrusion length a and pitch b of the convex portion from the driving frequency and amplitude of the movable portion 4 and the length L from the axial center of the torsion bars 3 and 3 to the edge portion 4a. A preferable dimension of the protrusion length a and the pitch b of the protrusion is about 1/5 to about 5 times the diameter of the vortex generated by the swinging motion of the movable portion 4. For example, the protrusion length a may be about 1/5 times the vortex diameter and the pitch b may be about 5 times the vortex diameter. Conversely, the protrusion length a is about 5 times the vortex diameter and the pitch b is about the vortex diameter. It is good also as 1/5 times. By making such a concavo-convex shape, the generation of vortices around the edge 4a of the movable part 4 can be sufficiently suppressed, and the vortex can be dispersed sufficiently finely, in the direction opposite to the direction of movement of the movable part acting on the edge 4a. The moment M can be made sufficiently small to improve the stability of the swinging motion of the movable part 4.

In the above embodiment, the uneven shape is triangular, but it may be a shape as shown in FIG. (A) is an example of the shape which rounded the top of the triangle. (B) is an example of a rectangular shape. (C) is an example of a semicircular waveform. (D) is an example of a rectangular fractal shape. In the case of the fractal shape, it is preferable that the projection length a and the pitch b of the convex portions of the small rectangular portion and the large rectangular portion are about 1/5 to about 5 times the vortex diameter.
Needless to say, the uneven shape of the edge 4a of the movable portion 4 is not limited to these shapes, and any shape that can sufficiently disperse the vortex and reduce the moment M can be used.

  Similarly, when the movable part 4 is a circular planar electromagnetic actuator 10 as shown in FIG. 3, the movable part edge 4 </ b> A substantially parallel to the axial direction of the torsion bars 3, 3 of the movable part 4 is provided. If it is formed in a concavo-convex shape, the same effect as the first embodiment can be obtained. In addition, in 2nd Embodiment of this invention shown in FIG. 3, the same code | symbol is attached | subjected to the element similar to 1st Embodiment. In FIG. 3, the drive coil 5, the electrode terminal 7, and the permanent magnet 6 are not shown.

Next, FIG. 4 shows a third embodiment of the present invention applied to a two-dimensional drive type planar electromagnetic actuator. In addition, the same code | symbol is attached | subjected to the same element as 1st Embodiment of FIG. 1, and description is abbreviate | omitted.
A planar electromagnetic actuator 20 of the two-dimensional drive type in FIG. 4 includes a frame-shaped outer movable portion 4A, in which the movable portion 4 is pivotally supported by the fixed portion 2 via the outer torsion bars 3A and 3A. The outer movable portion 4A includes the outer torsion bars 3A and 3A and the inner movable portion 4B that is pivotally supported via the inner torsion bars 3B and 3B whose axial directions are perpendicular to each other. And the both-ends edge part 4a substantially parallel to the axial direction of outer side torsion bar 3A, 3A of the outer side movable part 4A is made into uneven | corrugated shape similarly to 1st Embodiment of FIG. Further, both end edge portions 4b substantially parallel to the axial direction of the inner torsion bars 3B and 3B of the inner movable portion 4B and both side edge portions 4c substantially parallel to the axial direction of the outer torsion bars 3A and 3A have the same uneven shape. The outer movable portion 4A is provided with an outer drive coil 5A (indicated by a single line in the figure for simplification), and the inner movable portion 4B is provided with an inner drive coil 5B. The outer drive coil 5A is provided by being wound around the outer periphery of the outer movable portion 4A, and is electrically connected to the electrode terminals 7A and 7A through one outer torsion bar 3A portion. The inner drive coil 5B corresponds to the drive coil 5 described above and is electrically connected to the electrode terminals 7B and 7B through the inner torsion bars 3B and 3B, a part of the outer movable part 4A and the other outer torsion bar 3A. Connected. Further, the permanent magnets 6A and 6A and the permanent magnets 6B and 6B that make a pair are arranged on the outer side of the fixed portion 2 so that opposite magnetic poles face each other with the outer movable portion 4A and the inner movable portion 4B interposed therebetween as shown in the figure. Is provided.

  When an alternating current is supplied to the outer drive coil 5A and the inner drive coil 5B, the two-dimensional planar electromagnetic actuator 20 has an edge 4a of the outer movable portion 4A parallel to the axial direction of the outer torsion bars 3A, 3A. The outer movable portion 4A and the inner movable portion 4B are integrally rotated around the outer torsion bars 3A and 3A by the Lorentz force generated by the interaction between the magnetic field generated in the outer drive coil 5A portion and the static magnetic field of the permanent magnets 6A and 6A. To turn. Further, Lorentz generated by the interaction between the magnetic field generated in the inner drive coil 5B portion of the end edge 4b of the inner movable portion 4B parallel to the axial direction of the inner torsion bars 3B, 3B and the static magnetic field of the permanent magnets 6B, 6B. The inner movable portion 4B is rotated around the inner torsion bars 3B and 3B by the force. Thus, if the inner movable portion 4B is driven two-dimensionally and a reflection mirror is provided on the inner movable portion 4B, the reflected light of the mirror can be deflected in a two-dimensional direction, and the light beam can be scanned two-dimensionally. .

  When the outer movable parts 4A and 4A of the planar electromagnetic actuator 20 are swung in gas, vortices are generated in the vicinity of both end edges 4a of the outer movable part 4 and both side edges 4c of the inner movable part 4B. Each uneven shape can suppress the generation of vortices and the generated vortices are finely dispersed. Further, when the inner movable portions 4B and 4B are swung, the vortex generation can be suppressed by the uneven shape of the both end edges 4b of the inner movable portion 4B as in the first embodiment, and the generated vortex Finely dispersed. Therefore, the stability of the swing operation of the two-dimensional drive type planar electromagnetic actuator 20 can be improved.

  In the third embodiment, only the outer sides of both end edges 4a of the frame-shaped outer movable portion 4A are uneven, however, like the planar electromagnetic actuator 30 of the fourth embodiment shown in FIG. It is preferable that the inner side of both end edges 4a of the outer movable portion 4A also has an uneven shape. In addition, the other structure of the planar type electromagnetic actuator 30 of 4th Embodiment is the structure similar to 3rd Embodiment of FIG. 4, and the same code | symbol is attached | subjected to the element similar to 3rd Embodiment. In FIG. 5, the inner and outer drive coils 5A and 5B, the electrode terminals 7A and 7B, and the permanent magnets 6A and 6B are not shown.

  Needless to say, the uneven shape shown in FIG. 2 can also be applied to the third and fourth embodiments.

The top view which shows 1st Embodiment of the planar type electromagnetic actuator which concerns on this invention The figure which shows the example of another uneven | corrugated shape different from the uneven | corrugated shape of 1st Embodiment. The top view which shows 2nd Embodiment of this invention The top view which shows 3rd Embodiment of this invention The top view which shows 4th Embodiment of this invention Illustration of conventional problems

Explanation of symbols

1, 10, 20, 30 Planar type electromagnetic actuator 2 Fixed part 3 Torsion bar 3A, 3A Outer torsion bar 3B, 3B Inner torsion bar 4 Movable part 4A, 4A Outer movable part 4B, 4B Inner movable part 5 Drive coils 5A, 5A Outer drive coils 5B, 5B Inner drive coils 6, 6A, 6A, 6B, 6B Permanent magnets 4a, 4b End edges (uneven shape)
4c Side edge (uneven shape)

Claims (4)

In a planar type electromagnetic actuator that drives a movable part pivotally supported by a fixed part via a torsion bar by electromagnetic force,
An end edge portion substantially parallel to the axial direction of the torsion bar of the movable portion is formed into an uneven shape in a cross section of the movable portion parallel to the axial direction ,
The protrusion size and pitch of the convex portion at the end edge portion are determined from the diameter of the vortex determined in relation to the drive frequency and amplitude of the movable portion and the length from the axial center of the torsion bar to the end edge portion. A planar electromagnetic actuator characterized by having a configuration . Planar electromagnetic actuator according to claim 1, a protrusion dimension and pitch of the convex portions, and about 1/5 to about 5 times the diameter of the vortex. The movable part includes a frame-like outer movable part that is pivotally supported by the fixed part via an outer torsion bar, and an inner torsion bar that is perpendicular to the outer torsion bar in the axial direction. An inner movable portion that is pivotally supported via the inner movable portion, and an end edge portion substantially parallel to the axial direction of the outer torsion bar of the outer movable portion and the axial direction of the inner torsion bar of the inner movable portion. The planar electromagnetic actuator according to claim 1 or 2 , wherein substantially parallel end edges are formed into the uneven shape. The planar electromagnetic actuator according to claim 3 , wherein a side edge portion of the inner movable portion that is substantially parallel to the axial direction of the outer torsion bar has an uneven shape.

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