JP2004266150A - Planar electromagnetic actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a plurality of driving coils laminated in a pin hole from short-circuiting between the adjacent upper and lower layers even when a pin hole is made on an insulation film in the manufacturing process of a planar electromagnetic actuator. <P>SOLUTION: The planar electromagnetic actuator comprises a planar movable plate, a pair of torsion bars pivotally supporting the movable plate in a rotatable manner, the driving coils formed along the peripheral edge of the movable plate on at least one surface of the movable plate, and a pair of static magnetic field generating means arranged at the outer site of the movable plate in a direction orthogonal to the axial direction of the torsion bars. The driving coils are laminated, and the driving coils of respective layers are not overlapped at the upper and lower layers in the planar electromagnetic actuator. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a planar-type electromagnetic actuator that rotates a movable plate supported by a torsion bar by an electromagnetic force generated in a drive coil provided on the movable plate.
[0002]
[Prior art]
In a conventional planar electromagnetic actuator, a movable plate and a torsion bar are integrally formed by anisotropically etching a silicon substrate, and the movable plate is supported on a fixed portion of the silicon substrate by a torsion bar. A static magnetic field generating means for applying a static magnetic field to the drive coil made of a highly conductive metal thin film is provided along the peripheral edge of the coil, for example, a permanent magnet is provided. (For example, Patent Document 1)
[0003]
When a current is supplied to the drive coil of the planar electromagnetic actuator configured as described above, the static magnetic field generated by the static magnetic field generating means is changed to the current of the drive coil flowing through the opposite side of the movable plate parallel to the axial direction of the torsion bar. Acting to generate a Lorentz force on the drive coil to rotate the movable coil about the movable plate and the torsion bar. At this time, when a current having a frequency substantially equal to the natural frequency of the torsion bar and the movable plate is supplied to the drive coil, the movable plate resonates at this frequency and rotates efficiently.
[0004]
1A and 1B are views showing a planar type electromagnetic actuator, wherein FIG. 1A is a top view and FIG. 1B is a cross-sectional view along AA ′. The movable plate 1, the drive coil 2, and the permanent magnet 3. FIG. 2 is a cross-sectional view illustrating a manufacturing process of the drive coil. Hereinafter, the manufacturing process of the drive coil will be described with reference to FIG.
(A) A metal thin film 8 having good conductivity is formed on the movable plate 1.
(B) The metal thin film 8 is formed into a drive coil 4 by photolithography.
(C) An insulating film 5 is formed on the drive coil 4.
(D) A highly conductive metal thin film 8 is formed on the insulating film 5.
(E) The metal thin film 8 is formed into a drive coil 6 by photolithography.
[0005]
In the planar type electromagnetic actuator according to the related art, two-layer drive is performed by making contact at the inner end (contact portion) of the first-layer drive coil 4 and the inner end (contact portion) of the second-layer drive coil 6. The driving force is secured by using one coil as the coil and doubling the number of turns of the driving coil.
[0006]
In order to contact the first-layer drive coil and the second-layer drive coil, the contact portion of the first-layer drive coil 4 is exposed even if the insulating film 5 is formed. However, the first-layer drive coil 4 and the second-layer drive coil 6 must be insulated except for the contact portion.
[0007]
[Patent Document 1]
Patent Publication No. 2722314
[Problems to be solved by the invention]
When forming the second-layer drive coil 6 on the first-layer drive coil 4 via the insulating film 5, if the first-layer drive coil 4 is exposed from the insulating film, the first-layer drive coil 4 The coil 4 and the second-layer drive coil 6 are short-circuited except at the contact portion. If the first-layer drive coil 4 and the second-layer drive coil 6 are short-circuited at portions other than the contact portion, the actual number of turns of the drive coil decreases, and the Lorentz force generated in the drive coil decreases. The problem to be solved by the present invention is that even if the second-layer drive coil 6 is formed in a state in which portions other than the contact portion of the first-layer drive coil 4 are exposed from the insulating film, the first-layer drive coil 4 And that the second-layer drive coil 6 is not short-circuited except at the contact portion.
[0009]
The cause of the short circuit between the first-layer drive coil 4 and the second-layer drive coil 6 is in the manufacturing process. That is, after the first-layer drive coil 4 is formed, the insulating film 5 is formed on the upper surface of the coil, and the second-layer drive coil 6 is formed thereon. However, pinholes may be generated in the insulating film 5. If a pinhole is generated in the insulating film 5 on the first-layer drive coil 4, the first-layer drive coil 4 and the second-layer drive coil 6 are short-circuited.
[0010]
[Means for Solving the Problems]
A flat movable plate, a pair of torsion bars rotatably supporting the movable plate, a drive coil formed on at least one surface of the movable plate along a peripheral edge of the movable plate, A planar type electromagnetic actuator having a pair of static magnetic field generating means disposed on an outer portion of the movable plate in a direction perpendicular to an axial direction of a bar, wherein the drive coils are stacked, and drive of each layer is performed. The coil is a planar electromagnetic actuator that does not overlap between adjacent upper and lower layers.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. 3 and 4 are cross-sectional views showing the structure of the drive coil unit of the planar electromagnetic actuator according to one embodiment of the present invention. A first-layer drive coil 9 is formed of a metal film on the movable plate 1, and an insulating film 5 is formed to insulate the first-layer drive coil 9. A second-layer driving coil 10 is formed of a metal film on the insulating film 5 so as not to overlap with the first-layer driving coil 9. Further, a protective film 7 is formed to protect the second-layer drive coil 10. Since the planar type electromagnetic actuator of the present invention has a structure in which a plurality of stacked drive coils do not overlap in the upper and lower layers adjacent to each other, the pinhole 11 is generated in the insulating film 5 as shown in FIG. Even if the second-layer drive coil 10 is formed while the second-layer drive coil 9 is exposed, the first-layer drive coil 9 and the second-layer drive coil 10 are not short-circuited. Here, the case where the stacked drive coils have a two-layer structure has been described. However, even in the case of a drive coil in which a plurality of layers of three or more layers are stacked, similar effects can be obtained as long as the drive coils do not overlap in the upper and lower layers. Obtainable.
[0012]
FIG. 5 is a cross-sectional view showing another embodiment of the drive coil structure of the planar electromagnetic actuator of the present invention, in which two-layer drive coils are formed on both surfaces of the movable plate. The same effect can be obtained even when the two-layer drive coil is formed on both surfaces of the movable plate 1 as described above.
[0013]
According to the present invention, since a plurality of stacked drive coils do not overlap in the adjacent upper and lower layers, the width of the drive coil is narrower than that of a planar-type electromagnetic actuator manufactured by the related art. When the cross-sectional area of the drive coil decreases and the resistance value increases, the drive coil generates heat, which may adversely affect the rotation of the movable plate. Therefore, it is necessary to make the film thicker in order to lower the resistance value. Further, when the width of the stacked drive coils is different, a difference occurs in the resistance value of the drive coil. Therefore, by adjusting the film thickness so that the cross-sectional area of the drive coil becomes the same, the same resistance value as that of the related art is obtained. Things are possible.
[0014]
【The invention's effect】
According to the present invention, it is possible to eliminate a short circuit between a plurality of stacked drive coils in adjacent upper and lower layers, and to prevent a decrease in Lorentz force required for rotating the movable plate. Further, the yield of the stacked driving coil forming step could be improved.
[0015]
Even if a pinhole occurs in the insulating film, the drive coil does not short-circuit between the adjacent upper and lower layers, so that the operation of forming the insulating film is facilitated.
[Brief description of the drawings]
FIG. 1 is a diagram showing a planar type electromagnetic actuator, in which (A) is a front view and (B) is a cross-sectional view along AA ′.
FIG. 2 is a view showing a manufacturing process of a drive coil; FIG. 3 is a cross-sectional view showing a drive coil structure of a planar type electromagnetic actuator according to one embodiment of the present invention; FIG. FIG. 5 is a cross-sectional view showing a structure of a drive coil unit of an actuator. FIG. 5 is a cross-sectional view showing another embodiment of a drive coil unit of a planar electromagnetic actuator of the present invention.
REFERENCE SIGNS LIST 1 movable plate 2 drive coil 3 permanent magnet 4 first layer drive coil 5 insulating film 6 second layer drive coil 7 protective film 8 metal film 9 first layer drive coil 10 second layer drive coil 11 pinhole

Claims (1)

A flat movable plate, a pair of torsion bars rotatably supporting the movable plate, a drive coil formed on at least one surface of the movable plate along a peripheral edge of the movable plate, A planar type electromagnetic actuator having a pair of static magnetic field generating means disposed on an outer portion of the movable plate in a direction perpendicular to an axial direction of a bar, wherein the drive coils are stacked, and drive of each layer is performed. A planar type electromagnetic actuator characterized in that coils do not overlap between adjacent upper and lower layers.

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