Micro oscillating element

Abstract

A micro oscillating element includes a frame and an oscillation section connected to the frame via a torsional joining section. The oscillation section includes a movable functional section, an arm section and a first comb-tooth electrode. The arm section extends from the functional section. The first comb-tooth electrode includes first electrode teeth extending from the arm section in a direction intersecting the arm section. The micro oscillating element further includes a second comb-tooth electrode to cooperate with the first comb-tooth electrode for causing the oscillation section to oscillate about an oscillation axis defined by the torsional joining section. The second comb-tooth electrode includes second electrode teeth extending from the frame in a direction intersecting the arm section.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention generally relates to a micro oscillating element having an oscillation section capable of rotary displacement. In particular, the present invention relates to a micromirror element, an acceleration sensor, an angular velocity sensor, and a vibration element, for example. [0003] 2. Description of the Related Art [0004] In recent years, elements having a microstructure formed by micromachining technology have been put to practical use in various technological fields. In the field of optical communication technology, for example, minute micromirror elements having a light reflecting function are gaining attention. [0005] In optical communication, optical signals are transmitted using optical fiber as a medium, and an optical switching device is typically used to switch the transmission path of the optical signal from one fiber to another fiber. To achieve favorable optical communication, the chara...

AI Technical Summary

Benefits of technology

[0018] According to the present invention, the first electrode teeth of the first comb-tooth electrode are supported on the arm section, which extends from the movable functional section. The first electrode teeth may be arranged at predetermined intervals (i.e., spaced from each other) in the longitudinal direction of the arm section, while the second electrode teeth may be supported on the frame and arranged at predetermined intervals in the longitudinal direction of the arm section. It should be appreciated that the first electrode teeth (and the second electrode teeth) are not supported directly on the movable functional section. As a result, the number of electrode teeth (first electrode teeth, second electrode teeth) constituting the set of comb-tooth electrodes is not restricted by the length of the movable functional section in the longitudinal direction of the oscillation axis, which intersects the elongated arm section at a right angle, for example. Hence in the element of the present invention, a surface area which enables the electrode teeth of the first and second comb-tooth electrodes to face each other can be secured by providing the first and second electrode teeth in a desired number, regardless of the design dimension of the movable functional section in the oscillation axis direction. Since a surface area which enables the electrode teeth of the first and second comb-tooth electrodes to face each other is secured, there is no need to reduce the width or increase the extension length of the first and second electrode teeth to the extent that the mechanical strength of the first and second comb-tooth electrodes is adversely affected, and there is also no need to reduce the gap between electrode teeth to the extent that difficulties arise in the manufacturing process of the element. Accordingly, the element of the present invention is suitable for achieving miniaturization by reducing the design dimension of the movable functional section, and accordingly the entire element, in the oscillation axis direction while maintaining enough driving force to drive the oscillating operation of the oscillation section by providing the first and second electrode teeth in a desired number, regardless of the design dimension of the movable functional section in the oscillation axis direction.

[0019] Preferably, the first electrode teeth may extend in parallel to the oscillation axis, and the second electrode teeth may preferably extend in parallel to the first electrode teeth. By making the extension direction of the first and second electrode teeth parallel to the oscillation axis, the force to cause the oscillation section to oscillate about the oscillation axis can be generated efficiently.

[0021] The first comb-tooth electrode may preferably comprise at least three electrode teeth, and the distance between two adjacent first electrode teeth may preferably increase steadily as the teeth are farther from the oscillation axis. Further, the second comb-tooth electrode may preferably comprise at least three electrode teeth, and the distance between two adjacent second electrode teeth may preferably increase steadily as the teeth are away from the oscillation axis. As the first electrode teeth are further away from the oscillation axis, the displacement between the electrode teeth (as viewed in the extension direction of the arm section) during the oscillating operation of the oscillation section increases, and hence these constitutions are favorable for avoiding contact between the first electrode teeth and second electrode teeth during the oscillating operation of the oscillation section.

[0023] In a preferred aspect, the micro oscillating element of the present invention may further comprise a third comb-tooth electrode and a fourth comb-tooth electrode cooperating with the third comb-tooth electrode for causing the oscillation section to oscillate. The third comb-tooth electrode may comprise a plurality of third electrode teeth that extend from the arm section in a direction intersecting the arm section, and that are spaced from each other in a longitudinal direction of the arm section. The fourth comb-tooth electrode may comprise a plurality of fourth electrode teeth that extend from the frame in a direction intersecting the arm section. In this case, the fourth comb-tooth electrode may be electrically separated from the second comb-tooth electrode. In this case, the first and third comb-tooth electrodes may preferably be electrically connected to each other. According to this constitution, the electrostatic force generated between the first and second comb-tooth electrodes and the electrostatic force generated between the third and fourth comb-tooth electrodes can be caused to differ by making different the potential that is applied to the second comb-tooth electrode and the potential that is applied to the fourth comb-tooth electrode. As a result of this constitution, the rotary displacement of the movable functional section about a predetermined axis which intersects the oscillation axis can be controlled. In other words, the attitude of the movable functional section about this axis can be regulated.

[0024] In another preferred aspect, this micro oscillating element may further comprise an additional arm section extending from the movable functional section, a third comb-tooth electrode and a fourth comb-tooth electrode. The third comb-tooth electrode may comprise a plurality of third electrode teeth that extend from the additional arm section in a direction intersecting the additional arm section, and that are spaced from each other in a longitudinal direction of the additional arm section. The fourth comb-tooth electrode may comprise a plurality of fourth electrode teeth for causing the oscillation section to oscillate in cooperation with the third comb-tooth electrode. The fourth electrode teeth may be arranged to extend from the frame in a direction intersecting the additional arm section and to be spaced from each other in a longitudinal direction of the additional arm section. In this case, the first comb-tooth electrode and the third comb-tooth electrode may be electrically separated from each other. On the other hand, the second and the fourth comb-tooth electrodes may preferably be electrically connected to each other. According to this constitution, the electrostatic force generated between the first and second comb-tooth electrodes and the electrostatic force generated between the third and fourth comb-tooth electrodes can be caused to differ by making different the potential that is applied to the first comb-tooth electrode and the potential that is applied to the third comb-tooth electrode. As a result of this constitution, the rotary displacement of the movable functional section about a predetermined axis which intersects the oscillation axis can be controlled. In other words, the attitude of the movable functional section about this axis can be regulated.

Problems solved by technology

However, with surface micromachining technology, the mirror surface that is ultimately formed is thin, and therefore buckles easily.

Accordingly, it is difficult to achieve a high degree of flatness on a mirror surface with a large surface area.

However, shrinking the length L61 cannot easily be compatible with maintaining the driving force enough to oscillate the mirror supporting portion 61.

However, reducing the width d1 and increasing the length d3 of the electrode teeth lead to a reduction in mechanical strength in the width direction of the electrode teeth.

As a result, when a voltage is applied as described above with reference to FIG. 33B, the electrode teeth deform in the width direction thereof, causing a defect whereby the electrode teeth stick to adjacent teeth.

Further, reducing the gap d2 between the electrode teeth leads to difficulties in the manufacturing process of the micromirror element X6, decreases in yield, and so on.

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